CarbohydratesAssistant professor

Dr Mustafa Taha Mohammed

Carbohydrates

DEFINITION

Carbohydrates are polyhydroxy aldehydes or ketones or compounds which yield these on hydrolysis

Functionsbull sources of energybull intermediates in the biosynthesis of other basic

biochemical entities (fats and proteins)bull associated with other entities such as glycosides

vitamins and antibiotics)bull form structural tissues in plants and in

microorganisms (cellulose lignin murein)bull participate in biological transport cell-cell

recognition activation of growth factors modulation of the immune system

Glucose (a monosaccharide)

Plants

photosynthesis chlorophyll

6 CO2 + 6 H2O C6H12O6 + 6 O2 sunlight (+)-glucose

(+)-glucose starch or cellulose

respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

Carbohydrates

bull glucose provides energy for the brain and frac12 of energy for muscles and tissues

bull glycogen is stored glucosebull glucose is immediate energybull glycogen is reserve energy

Carbohydrates ndash polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n or compounds that can be hydrolyzed to them (aka sugars or saccharides)

Monosaccharides ndash carbohydrates that cannot be hydrolyzed to simpler carbohydrates eg Glucose or fructose

Disaccharides ndash carbohydrates that can be hydrolyzed into two monosaccharide units eg Sucrose which is hydrolyzed into glucose and fructose

Oligosaccharides ndash carbohydrates that can be hydrolyzed into a few monosaccharide units

Polysaccharides ndash carbohydrates that are are polymeric sugars eg Starch or cellulose

Classification of carbohydrates

Monosaccharides - simple sugars with multiple OH groups Based on number of carbons (3 4 5 6) a monosaccharide is a triose tetrose pentose or hexose

Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently

linked Polysaccharides - polymers consisting of chains of

monosaccharide or disaccharide units

I (CH2O)n or H - C - OH

I

Carbohydrates (glycans) have the following basic composition

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Carbohydrates

DEFINITION

Carbohydrates are polyhydroxy aldehydes or ketones or compounds which yield these on hydrolysis

Functionsbull sources of energybull intermediates in the biosynthesis of other basic

biochemical entities (fats and proteins)bull associated with other entities such as glycosides

vitamins and antibiotics)bull form structural tissues in plants and in

microorganisms (cellulose lignin murein)bull participate in biological transport cell-cell

recognition activation of growth factors modulation of the immune system

Glucose (a monosaccharide)

Plants

photosynthesis chlorophyll

6 CO2 + 6 H2O C6H12O6 + 6 O2 sunlight (+)-glucose

(+)-glucose starch or cellulose

respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

Carbohydrates

bull glucose provides energy for the brain and frac12 of energy for muscles and tissues

bull glycogen is stored glucosebull glucose is immediate energybull glycogen is reserve energy

Carbohydrates ndash polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n or compounds that can be hydrolyzed to them (aka sugars or saccharides)

Monosaccharides ndash carbohydrates that cannot be hydrolyzed to simpler carbohydrates eg Glucose or fructose

Disaccharides ndash carbohydrates that can be hydrolyzed into two monosaccharide units eg Sucrose which is hydrolyzed into glucose and fructose

Oligosaccharides ndash carbohydrates that can be hydrolyzed into a few monosaccharide units

Polysaccharides ndash carbohydrates that are are polymeric sugars eg Starch or cellulose

Classification of carbohydrates

Monosaccharides - simple sugars with multiple OH groups Based on number of carbons (3 4 5 6) a monosaccharide is a triose tetrose pentose or hexose

Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently

linked Polysaccharides - polymers consisting of chains of

monosaccharide or disaccharide units

I (CH2O)n or H - C - OH

I

Carbohydrates (glycans) have the following basic composition

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

DEFINITION

Carbohydrates are polyhydroxy aldehydes or ketones or compounds which yield these on hydrolysis

Functionsbull sources of energybull intermediates in the biosynthesis of other basic

biochemical entities (fats and proteins)bull associated with other entities such as glycosides

vitamins and antibiotics)bull form structural tissues in plants and in

microorganisms (cellulose lignin murein)bull participate in biological transport cell-cell

recognition activation of growth factors modulation of the immune system

Glucose (a monosaccharide)

Plants

photosynthesis chlorophyll

6 CO2 + 6 H2O C6H12O6 + 6 O2 sunlight (+)-glucose

(+)-glucose starch or cellulose

respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

Carbohydrates

bull glucose provides energy for the brain and frac12 of energy for muscles and tissues

bull glycogen is stored glucosebull glucose is immediate energybull glycogen is reserve energy

Carbohydrates ndash polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n or compounds that can be hydrolyzed to them (aka sugars or saccharides)

Monosaccharides ndash carbohydrates that cannot be hydrolyzed to simpler carbohydrates eg Glucose or fructose

Disaccharides ndash carbohydrates that can be hydrolyzed into two monosaccharide units eg Sucrose which is hydrolyzed into glucose and fructose

Oligosaccharides ndash carbohydrates that can be hydrolyzed into a few monosaccharide units

Polysaccharides ndash carbohydrates that are are polymeric sugars eg Starch or cellulose

Classification of carbohydrates

Monosaccharides - simple sugars with multiple OH groups Based on number of carbons (3 4 5 6) a monosaccharide is a triose tetrose pentose or hexose

Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently

linked Polysaccharides - polymers consisting of chains of

monosaccharide or disaccharide units

I (CH2O)n or H - C - OH

I

Carbohydrates (glycans) have the following basic composition

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Functionsbull sources of energybull intermediates in the biosynthesis of other basic

biochemical entities (fats and proteins)bull associated with other entities such as glycosides

vitamins and antibiotics)bull form structural tissues in plants and in

microorganisms (cellulose lignin murein)bull participate in biological transport cell-cell

recognition activation of growth factors modulation of the immune system

Glucose (a monosaccharide)

Plants

photosynthesis chlorophyll

6 CO2 + 6 H2O C6H12O6 + 6 O2 sunlight (+)-glucose

(+)-glucose starch or cellulose

respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

Carbohydrates

bull glucose provides energy for the brain and frac12 of energy for muscles and tissues

bull glycogen is stored glucosebull glucose is immediate energybull glycogen is reserve energy

Carbohydrates ndash polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n or compounds that can be hydrolyzed to them (aka sugars or saccharides)

Monosaccharides ndash carbohydrates that cannot be hydrolyzed to simpler carbohydrates eg Glucose or fructose

Disaccharides ndash carbohydrates that can be hydrolyzed into two monosaccharide units eg Sucrose which is hydrolyzed into glucose and fructose

Oligosaccharides ndash carbohydrates that can be hydrolyzed into a few monosaccharide units

Polysaccharides ndash carbohydrates that are are polymeric sugars eg Starch or cellulose

Classification of carbohydrates

Monosaccharides - simple sugars with multiple OH groups Based on number of carbons (3 4 5 6) a monosaccharide is a triose tetrose pentose or hexose

Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently

linked Polysaccharides - polymers consisting of chains of

monosaccharide or disaccharide units

I (CH2O)n or H - C - OH

I

Carbohydrates (glycans) have the following basic composition

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Glucose (a monosaccharide)

Plants

photosynthesis chlorophyll

6 CO2 + 6 H2O C6H12O6 + 6 O2 sunlight (+)-glucose

(+)-glucose starch or cellulose

respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

Carbohydrates

bull glucose provides energy for the brain and frac12 of energy for muscles and tissues

bull glycogen is stored glucosebull glucose is immediate energybull glycogen is reserve energy

Carbohydrates ndash polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n or compounds that can be hydrolyzed to them (aka sugars or saccharides)

Monosaccharides ndash carbohydrates that cannot be hydrolyzed to simpler carbohydrates eg Glucose or fructose

Disaccharides ndash carbohydrates that can be hydrolyzed into two monosaccharide units eg Sucrose which is hydrolyzed into glucose and fructose

Oligosaccharides ndash carbohydrates that can be hydrolyzed into a few monosaccharide units

Polysaccharides ndash carbohydrates that are are polymeric sugars eg Starch or cellulose

Classification of carbohydrates

Monosaccharides - simple sugars with multiple OH groups Based on number of carbons (3 4 5 6) a monosaccharide is a triose tetrose pentose or hexose

Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently

linked Polysaccharides - polymers consisting of chains of

monosaccharide or disaccharide units

I (CH2O)n or H - C - OH

I

Carbohydrates (glycans) have the following basic composition

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Carbohydrates

bull glucose provides energy for the brain and frac12 of energy for muscles and tissues

bull glycogen is stored glucosebull glucose is immediate energybull glycogen is reserve energy

Carbohydrates ndash polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n or compounds that can be hydrolyzed to them (aka sugars or saccharides)

Monosaccharides ndash carbohydrates that cannot be hydrolyzed to simpler carbohydrates eg Glucose or fructose

Disaccharides ndash carbohydrates that can be hydrolyzed into two monosaccharide units eg Sucrose which is hydrolyzed into glucose and fructose

Oligosaccharides ndash carbohydrates that can be hydrolyzed into a few monosaccharide units

Polysaccharides ndash carbohydrates that are are polymeric sugars eg Starch or cellulose

Classification of carbohydrates

Monosaccharides - simple sugars with multiple OH groups Based on number of carbons (3 4 5 6) a monosaccharide is a triose tetrose pentose or hexose

Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently

linked Polysaccharides - polymers consisting of chains of

monosaccharide or disaccharide units

I (CH2O)n or H - C - OH

I

Carbohydrates (glycans) have the following basic composition

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Carbohydrates ndash polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n or compounds that can be hydrolyzed to them (aka sugars or saccharides)

Monosaccharides ndash carbohydrates that cannot be hydrolyzed to simpler carbohydrates eg Glucose or fructose

Disaccharides ndash carbohydrates that can be hydrolyzed into two monosaccharide units eg Sucrose which is hydrolyzed into glucose and fructose

Oligosaccharides ndash carbohydrates that can be hydrolyzed into a few monosaccharide units

Polysaccharides ndash carbohydrates that are are polymeric sugars eg Starch or cellulose

Classification of carbohydrates

Monosaccharides - simple sugars with multiple OH groups Based on number of carbons (3 4 5 6) a monosaccharide is a triose tetrose pentose or hexose

Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently

linked Polysaccharides - polymers consisting of chains of

monosaccharide or disaccharide units

I (CH2O)n or H - C - OH

I

Carbohydrates (glycans) have the following basic composition

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Monosaccharides - simple sugars with multiple OH groups Based on number of carbons (3 4 5 6) a monosaccharide is a triose tetrose pentose or hexose

Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently

linked Polysaccharides - polymers consisting of chains of

monosaccharide or disaccharide units

I (CH2O)n or H - C - OH

I

Carbohydrates (glycans) have the following basic composition

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Simple Carbohydrates

bull sugarsndash monosaccharides ndash single sugarsndash disaccharides ndash 2 monosaccharides

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Monosaccharides

bull also known as simple sugarsbull classified by 1 the number of carbons and 2

whether aldoses or ketosesbull most (99) are straight chain compoundsbull D-glyceraldehyde is the simplest of the aldoses

(aldotriose)bull all other sugars have the ending ose (glucose

galactose ribose lactose etchellip)

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

GlucoseThe chemical formula

for glucose is C6H12O6

It is a six sided ringThe structure on the

left is a simplified structure of glucose

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Monosaccharides

Aldoses (eg glucose) have an aldehyde group at one end

Ketoses (eg fructose) have a keto group usually at C2

C

C OHH

C HHO

C OHH

C OHH

CH2OH

D-glucose

OH

C HHO

C OHH

C OHH

CH2OH

CH2OH

C O

D-fructose

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

bull Compounds having same structural formula but differ in spatial configuration

bull Asymmetric Carbon atomAttached to four different atoms or groups

bull Vant Hoffrsquos rule The possible isomers (2n) of a given compound is determined by the number of asymmetric carbon atoms (n)

bull Reference C atom Penultimate C atom around which mirror images are formed

chiral centers by definition are C atoms which have 4 DIFFERENT atoms bonded to it

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Sugar Nomenclature

For sugars with more than one chiral center D or L refers to the asymmetric C farthest from the aldehyde or keto group

Most naturally occurring sugars are D isomers

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

D amp L sugars are mirror images of one another They have the same name eg D-glucose amp L-glucose Other stereoisomers have unique names eg glucose mannose galactose etc

The number of stereoisomers is 2n where n is the number of asymmetric centers The 6-C aldoses have 4 asymmetric centers Thus there are 16 stereoisomers (8 D-sugars and 8 L-sugars)

O H O H C C H ndash C ndash OH HO ndash C ndash H HO ndash C ndash H H ndash C ndash OH H ndash C ndash OH HO ndash C ndash H H ndash C ndash OH HO ndash C ndash H CH2OH CH2OH

D-glucose L-glucose

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

D vs L Designation

D amp L designations are based on the configuration about the single asymmetric C in glyceraldehyde

The lower representations are Fischer Projections

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

CHO

C

CH2OH

HO H

CHO

C

CH2OH

H OH

L-glyceraldehydeD-glyceraldehyde

L-glyceraldehydeD-glyceraldehyde

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Enantiomres A special type of isomerism is found in the pairs of structures that are mirror images of each other These mirror images are called enantiomers and the two members of the pair are designated as a D- and an L-sugar

two monosaccharides differ in configuration around only one specific carbon atom (with the exception of the carbonyl carbon see below) they are defined as epimers of each other

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

(+)-glucose An aldohexose

Emil Fischer (1902)

Four chiral centers 24 = 16 stereoisomers

CHO

CH2OH

OH

CH2CHCHCHCHCH OOH OHOHOHOH

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Fructose forms either a 6-member pyranose ring by reaction of the C2 keto

group with the OH on C6 or a 5-member furanose ring by reaction of the C2 keto

group with the OH on C5

CH2OH

C O

C HHO

C OHH

C OHH

CH2OH

HOH2C

OH

CH2OH

HOH H

H HO

O

1

6

5

4

3

2

6

5

4 3

2

1

D-fructose (linear) -D-fructofuranose

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Epimers ndash stereoisomers that differ only in configuration about one chiral center

CHOOHHHHOOHHOHH

CH2OH

D-glucose

CHOHHOHHOOHHOHH

CH2OH

D-mannose

epimers

Sugars are different from one another only in configuration with regard to a single C atom (other than the reference C atom)

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

C

CH2OH

OHH

C O

H

C OHH

C

CH2OH

HOH

C O

H

C HOH

these two aldotetroses are enantiomersThey are stereoisomers that are mirrorimages of each other

C O

H

C HHO

C HHO

CH OH

C

CH2OH

OHH

C O

H

C HHO

C HHO

CHO H

C

CH2OH

OHH

these two aldohexoses are C-4 epimersthey differ only in the position of thehydroxyl group on one asymmetric carbon(carbon 4)

Enantiomers and epimers

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

bull OPTICAL ACTIVITY

bull Dextrorotatory (+) If the sugar solution turns the plane of polarized light to right

Levorotatory (ndash) If the sugar solution turns the plane of polarized light to left

bull Racemic mixtureEquimolar mixture of optical isomers has no net rotation

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Hemiacetal amp hemiketal formation

An aldehyde can react with an alcohol to form a hemiacetal

A ketone can react with an alcohol to form a hemiketal

O C

H

R

OH

O C

R

R

OHC

R

R

O

aldehyde alcohol hemiacetal

ketone alcohol hemiketal

C

H

R

O RR OH

R OH R

+

+

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

3 Fructose (levulsoe) --- Rotation in polarimeter is left

D-Fructose b-D-Fructose -D-Fructose

CH2OH

O

CH2OH

C

HO HC

OHCH

H C

OH

O

CH2OH

C

HO HC

OHCH

H C

CH2OHCH2OH

CH

HO

H C OH

C HHO

C

OH

CH2OH

O

or

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Anomers Stereoisomers formed when ring is formed ( b)

CO

CH2OH

OHCH

HO

H

HC

OH

OH

CH

HO

HO HC

OH

C H

H C OH

C H

H

HO

H C

CH2OH

O

C C

O

CH2OH

CH

HO

H

HC

OHCH

HC

OH

or

is same side with ring

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Rules for drawing Haworth projections

bull next number the ring clockwise starting next to the oxygen

bull if the substituent is to the right in the Fisher projection it will be drawn down in the Haworth projection (Down-Right Rule)

O O1

23

4

5

1

23

4

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Rules for drawing Haworth projections

bull draw either a six or 5-membered ring including oxygen as one atom

bull most aldohexoses are six-memberedbull aldotetroses aldopentoses ketohexoses are

5-membered

O O

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Pentoses and hexoses can cyclize as the ketone or aldehyde reacts with a distal OHGlucose forms an intra-molecular hemiacetal as the C1 aldehyde amp C5 OH react to form a 6-member pyranose ring named after pyran These representations of the cyclic sugars are called Haworth projections

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

D-glucose can cyclize in twoways forming either furanose orpyranose structures

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

D-ribose and other five-carbonsaccharides can form eitherfuranose or pyranose structures

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Cyclization of glucose produces a new asymmetric center at C1 The 2 stereoisomers are called anomers amp b Haworth projections represent the cyclic sugars as having essentially planar rings with the OH at the anomeric C1

(OH below the ring) b (OH above the ring)

H O

OH

H

OHH

OH

CH2OH

H

-D-glucose

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

b-D-glucose

23

4

5

6

1 1

6

5

4

3 2

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Chair and boat conformations of a pyranose sugar

2 possible chair conformationsof b-D-glucose

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Because of the tetrahedral nature of carbon bonds pyranose sugars actually assume a chair or boat configuration depending on the sugar

The representation above reflects the chair configuration of the glucopyranose ring more accurately than the Haworth projection

O

H

HO

H

HO

H

OHOHH

H

OH

O

H

HO

H

HO

H

HOHH

OH

OH

-D-glucopyranose b-D-glucopyranose

1

6

5

4

32

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Structural representation of sugars

bull Fisher projection straight chain representation

bull Haworth projection simple ring in perspective

bull Conformational representation chair and boat configurations

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Different Forms of Glucose

copyright cmassengale

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Oxygen of the hydroxyl group is removed to form deoxy sugars1048698Non reducing and non osazone forming1048698Important part of nucleic acids

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Simple Carbs

bull monosaccharidesndash all are 6 carbon hexes

bull 6 carbonsbull 12 hydrogensbull 6 oxygensbull arrangement differs

ndash accounts for varying sweetnessndash glucose fructose galactose

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Three Monosaccharides

C6H12O6

copyright cmassengale

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

OH

HO

H

HO

H

HOHH OH

OHO

H

HO

H

HO

H

OHOHH H

OH

hemiacetal

4H-Pyran

OD-glucopyranoses

alpha beta

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

OH

H

HH OH

HO HO

HHOHO

H

OH

HH OH

HO HO

HHOHO

O

furan

alpha furanose form beta furanose form

D-glucofuranoses

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Rules for drawing Haworth projections

bull for D-sugars the highest numbered carbon (furthest from the carbonyl) is drawn up For L-sugars it is drawn down

bull for D-sugars the OH group at the anomeric position is drawn down for and up for b For L-sugars is up and b is down

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Optical isomerism

bull A property exhibited by any compound whose mirror images are non-superimposable

bull Asymmetric compounds rotate plane polarized light

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

POLARIMETRY Measurement of optical activity in chiral or asymmetric

molecules using plane polarized light Molecules may be chiral because of certain atoms or

because of chiral axes or chiral planes

Measurement uses an instrument called a polarimeter (Lippich type)

Rotation is either (+) dextrorotatory or (-) levorotatory

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

polarimetry

Magnitude of rotation depends upon1 the nature of the compound

2 the length of the tube (cell or sample container) usually expressed in decimeters (dm)

3 the wavelength of the light source employed usually either sodium D line at 5893 nm or mercury vapor lamp at 5461 nm

4 temperature of sample

5 concentration of analyte in grams per 100 ml

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

bull Whatrsquos So Great About Chiral Moleculesbull bull Molecules which are enantiomers of each other havebull exactly the same physical properties (melting pointbull boiling point index of refraction etc) but not theirbull interaction with polarized lightbull bull Polarized light vibrates only in one plane it resultsbull from passing light through a polarizing filter

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

[]DT

l x c observed x 100 =

D = Na D lineT = temperature oC obs observed rotation in degree (specify solvent)l = length of tube in decimeterc = concentration in grams100ml[] = specific rotation

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Specific rotation of various carbohydrates at 20oC

bull D-glucose +527bull D-fructose -924bull D-galactose +802bull L-arabinose +1045bull D-mannose +142bull D-arabinose -1050bull D-xylose +188bull Lactose +554bull Sucrose +665bull Maltose+ +1304bull Invert sugar -198bull Dextrin +195

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

CHOOHHHHOOHHOHH

CH2OH

(+)-glucose

Exists only in solution There are two solids

α-glucose m 146o [α] = +1122

β-glucose m 150o [α] = +175

In water each mutarotates to an equilibrium with [α] = +527

(636 β 364 α)

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

CHOOHHHHOOHHOHH

CH2OH

OH

HO

H

HO

H

OHOHH H

OH

OH

HO

H

HO

H

HOHH OH

OH

alpha-(+)-glucose beta-(+)-glucose

OH

OH

OH

HH

OHH

OH

CH2OHOH

OH

H

OHH

OHH

OH

CH2OH

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Glucose oxidase

bull glucose oxidase converts glucose to gluconic acid and hydrogen peroxide

bull when the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed

bull this forms the basis for the measurement of urinary and blood glucose

bull Testape Clinistix Diastix (urinary glucose)bull Dextrostix (venous glucose)

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Reductionbull either done catalytically (hydrogen and a catalyst)

or enzymaticallybull the resultant product is a polyol or sugar alcohol

(alditol)bull glucose form sorbitol (glucitol)bull mannose forms mannitolbull fructose forms a mixture of mannitol and sorbitolbull glyceraldehyde gives glycerol

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Glycosidic BondsThe anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together splitting out water to form a glycosidic bond

R-OH + HO-R R-O-R + H2OEg methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl-glucopyranose)

O

H

HO

H

HO

H

OHOHH

H

OH

-D-glucopyranose

O

H

HO

H

HO

H

OCH3

OHHH

OH

methyl- -D-glucopyranose

CH 3-O H+

methanol

H2O

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

CH2OHOHHOOHHOHH

CH2OH

D-fructose

CH2OH

OH

H

CH2OH

OH H

H OHO

beta-D-fructofuranose

OH

CH2OH

H

CH2OH

OH H

H OHO

alpha-D-fructofuranose

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Sugar derivatives

sugar alcohol - lacks an aldehyde or ketone eg ribitol sugar acid - the aldehyde at C1 or OH at C6 is oxidized

to a carboxylic acid eg gluconic acid glucuronic acid

CH2OH

C

C

C

CH2OH

H OH

H OH

H OH

D-ribitol

COOH

C

C

C

C

H OH

HO H

H OH

D-gluconic acid D-glucuronic acid

CH2OH

OHH

CHO

C

C

C

C

H OH

HO H

H OH

COOH

OHH

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Sugar derivatives

amino sugar - an amino group substitutes for a hydroxyl An example is glucosamine The amino group may be acetylated as in N-acetylglucosamine

H O

OH

H

OH

H

NH2H

OH

CH2OH

H

-D-glucosamine

H O

OH

H

OH

H

NH

OH

CH2OH

H

-D-N-acetylglucosamine

C CH3

O

H

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

The anomeric forms ofmethyl-D-glucoside

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Cellobiose a product of cellulose breakdown is the otherwise equivalent b anomer (O on C1 points up) The b(1reg 4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other

H O

O H

H

O HH

O H

CH 2O H

HO H

O H

H

O HH

O H

CH 2O H

H

O

HH

1

23

5

4

6

1

23

4

5

6

m altose

H O

O H

H

O HH

O H

CH 2O H

HO O H

H

H

O HH

O H

CH 2O H

H

H

H

O1

23

4

5

6

1

23

4

5

6

cellobiose

DisaccharidesMaltose a cleavage product of starch (eg amylose) is a disaccharide with an (1reg 4) glycosidic link between C1 - C4 OH of 2 glucoses It is the anomer (C1 O points down)

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Other disaccharides include Sucrose common table sugar has a glycosidic bond

linking the anomeric hydroxyls of glucose amp fructose Because the configuration at the anomeric C of glucose

is (O points down from ring) the linkage is (1reg2) The full name of sucrose is -D-glucopyranosyl-(1reg2)-b-D-fructopyranose)

Lactose milk sugar is composed of galactose amp glucose with b(1reg4) linkage from the anomeric OH of galactose Its full name is b-D-galactopyranosyl-(1reg 4)--D-glucopyranose

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Disaccharides

(+)-maltose ldquomalt sugarrdquo

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose ldquomilk sugarrdquo

galactose amp glucose

(+)-sucrose ldquotable sugarrdquo

glucose amp fructose

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

SUCROSEbull Cane sugar

bull α-D-glucose ampβ-D-fructose units held together by (α1rarrβ2) glycosidic bond

bull Reducing groups in both are involved in bond formation hence non reducing

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

LACTOSE Principal sugar in milk

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

β-D-galactose amp β-D-glucose units held together by β(1rarr4) glycosidic bond

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Malt sugarProduced during the course of digestion of starch by the enzyme amylaseTwo α-D-glucose units held together by α(1rarr4) glycosidic bond

MALTOSE

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

bull ReducingMaltose Lactose ndashwith free aldehyde or keto group

bull Non-reducingSucrose Trehalose ndashno free aldehyde or keto group

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Sucrose 2-0--D-Glucopyranosyl b-D-Fructofuranoside

O

OH

OHHO

CH2OHCH2OH

OCH2OH

O

HO

OH

H1

23 4

5

6

Invert Sugar --- when sucrose in solution the rotation changes from detrorotatory (+665) to levorotatory (-198) So sucrose is called ldquoInvert Sugarrdquo Sucrose has been hydrolyzed into glucose and fructose

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Oligosaccharides

bull Most common are the disaccharidesbull Sucrose lactose and maltosebull Maltose hydrolyzes to 2 molecules of D-glucosebull Lactose hydrolyzes to a molecule of glucose and a

molecule of galactosebull Sucrose hydrolyzes to a moledule of glucose and a

molecule of fructose

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

PolysaccharidesPlants store glucose as amylose or amylopectin glucose polymers collectively called starch Glucose storage in polymeric form minimizes osmotic effectsAmylose is a glucose polymer with (1reg4) linkages The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the reducing end

H O

OHH

OHH

OH

CH 2 OH

HO H

H

OHH

OH

CH 2 OH

H

O

HH H O

OH

OHH

OH

CH 2 OH

HH H O

H

OHH

OH

CH 2 OH

H

OH

HH O

OH

OHH

OH

CH 2 OH

H

O

H1

6

5

4

3

1

2

a m y lo s e

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Dehydration Synthesisof a Disaccharide

copyright cmassengale

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Formation of Disaccharides

copyright cmassengale

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Starches

bull stored in plant cellsbull body hydrolyzes plant starch to glucose

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Starch

bull most common storage polysaccharide in plants

bull composed of 10 ndash 30 -amylose and 70-90 amylopectin depending on the source

bull the chains are of varying length having molecular weights from several thousands to half a million

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Polysaccharides

starch

cellulose

Starch 20 amylose (water soluble)

80 amylopectin (water insoluble)

amylose + H2O (+)-maltose

(+)-maltose + H2O (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Amylose and amylopectin are the 2 forms of starch Amylopectinis a highly branched structure with branches occurring every 12to 30 residues

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Amylopectin is a glucose polymer with mainly (1reg4) linkages but it also has branches formed by (1reg6) linkages Branches are generally longer than shown aboveThe branches produce a compact structure amp provide multiple chain ends at which enzymatic cleavage can occur

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

amylopectin

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Glycogen the glucose storage polymer in animals is similar in structure to amylopectin But glycogen has more (1reg6) branches The highly branched structure permits rapid glucose release from glycogen stores eg in muscle during exercise The ability to rapidly mobilize glucose is more essential to animals than to plants

H O

OHH

OHH

OH

CH 2OH

HO H

H

OHH

OH

CH 2OH

H

O

HH H O

OH

OHH

OH

CH 2

HH H O

H

OHH

OH

CH 2OH

H

OH

HH O

OH

OHH

OH

CH 2OH

H

O

H

O

1 4

6

H O

H

OHH

OH

CH 2OH

HH H O

H

OHH

OH

CH 2OH

HH

O1

OH

3

4

5

2

glycogen

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Cellulosebull Polymer of b-D-glucose attached by b(14) linkagesbull Only digested and utilized by ruminants (cows deers

giraffes camels)bull A structural polysaccharidebull Yields glucose upon complete hydrolysisbull Partial hydrolysis yields cellobiosebull Most abundant of all carbohydrates

bull Cotton flax 97-99 cellulosebull Wood ~ 50 cellulose

bull Gives no color with iodinebull Held together with lignin in woody plant tissues

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Cellulose a major constituent of plant cell walls consists of long linear chains of glucose with b(1reg4) linkagesEvery other glucose is flipped over due to b linkages This promotes intra-chain and inter-chain H-bonds and

c e l lu lo s e

H O

OHH

OHH

OH

CH 2 OH

HO

H

OHH

OH

CH 2 OH

HO

H H O

O H

OHH

OH

CH 2 OH

HH O

H

OHH

OH

CH 2 OH

H

H

OHH O

O H

OHH

OH

CH 2 OH

HO

H H H H

1

6

5

4

3

1

2

van der Waals interactions that cause cellulose chains to be straight amp rigid and pack with a crystalline arrangement in thick bundles - microfibrils See Botany online website website at Georgia Tech

Schematic of arrangement of cellulose chains in a microfibril

Oligosaccharides

bull Trisaccharide raffinose (glucose galactose and fructose)

bull Tetrasaccharide stachyose (2 galactoses glucose and fructose)

bull Pentasaccharide verbascose (3 galactoses glucose and fructose)

bull Hexasaccharide ajugose (4 galactoses glucose and fructose)

Special monosaccharides amino sugarsConstituents of mucopolysaccharides

Glycogen

bull also known as animal starchbull stored in muscle and liver (mostly)bull present in cells as granules (high MW)bull contains both (14) links and (16) branches at

every 8 to 12 glucose unit (more frequent than in starch)

bull complete hydrolysis yields glucosebull glycogen and iodine gives a red-violet colorbull hydrolyzed by both and b-amylases and by

glycogen phosphorylase

A portion of the structure of heparin

Heparin is a carbohydrate with anticoagulant properties It is used in bloodbanks to prevent clotting and in the prevention of blood clots in patients recovering from serious injury or surgery

Numerous derivatives of heparin have been made (LMWH enoxaparin (Lovenox) dalteparin (Fragmin) tinzaparin (Innohep) fondaparinux

Honey also contains glucose and fructose along withsome volatile oils

O-linked oligosaccharide chains of glycoproteins vary in complexity They link to a protein via a glycosidic bond between a sugar residue amp a serine or threonine OH O-linked oligosaccharides have roles in recognition interaction and enzyme regulation

H O

OH

O

H

HNH

OH

CH2OH

H

C CH3

O

b-D-N-acetylglucosamine

CH2 CH

C

NH

O

H

serine residue

Oligosaccharides that are covalently attached to proteins or to membrane lipids may be linear or branched chains

شكرا الصغائكمد مصطفى طه محمدالفيس بوك

Tahabiochemyahoocomالبريد االلكتروني

• Slide 1
• Carbohydrates
• Slide 3
• Functions
• Slide 5
• Carbohydrates (2)
• Slide 7
• Slide 8
• Simple Carbohydrates
• Monosaccharides
• Slide 11
• Glucose
• Slide 13
• Monosaccharides (2)
• Slide 15
• Sugar Nomenclature
• Slide 17
• D vs L Designation
• Slide 19
• Slide 20
• Slide 21
• Slide 22
• Slide 23
• Enantiomers and epimers
• Slide 25
• Hemiacetal amp hemiketal formation
• Slide 27
• Slide 28
• Rules for drawing Haworth projections
• Rules for drawing Haworth projections (2)
• Slide 31
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Structural representation of sugars
• Slide 38
• Slide 39
• Simple Carbs
• Slide 41
• Slide 42
• Slide 43
• Rules for drawing Haworth projections (3)
• Optical isomerism
• POLARIMETRY
• polarimetry
• Slide 48
• Slide 49
• Slide 50
• Specific rotation of various carbohydrates at 20oC
• Slide 52
• Slide 53
• Glucose oxidase
• Reduction
• Slide 56
• Glycosidic Bonds
• Slide 58
• Slide 59
• Sugar derivatives
• Sugar derivatives (2)
• Slide 62
• Slide 63
• Slide 64
• Slide 65
• Slide 66
• SUCROSE
• Slide 68
• Slide 69
• Slide 70
• Slide 71
• Oligosaccharides
• Slide 73
• Slide 74
• Slide 75
• Starches
• Starch
• Slide 78
• Slide 79
• Slide 80
• Slide 81
• Cellulose
• Slide 83
• Oligosaccharides (2)
• Slide 85
• Slide 86
• Glycogen
• Slide 88
• Slide 89
• Slide 90
• Slide 91

Special monosaccharides amino sugarsConstituents of mucopolysaccharides

Glycogen

bull also known as animal starchbull stored in muscle and liver (mostly)bull present in cells as granules (high MW)bull contains both (14) links and (16) branches at

every 8 to 12 glucose unit (more frequent than in starch)

bull complete hydrolysis yields glucosebull glycogen and iodine gives a red-violet colorbull hydrolyzed by both and b-amylases and by

glycogen phosphorylase

A portion of the structure of heparin

Heparin is a carbohydrate with anticoagulant properties It is used in bloodbanks to prevent clotting and in the prevention of blood clots in patients recovering from serious injury or surgery

Numerous derivatives of heparin have been made (LMWH enoxaparin (Lovenox) dalteparin (Fragmin) tinzaparin (Innohep) fondaparinux

Honey also contains glucose and fructose along withsome volatile oils

O-linked oligosaccharide chains of glycoproteins vary in complexity They link to a protein via a glycosidic bond between a sugar residue amp a serine or threonine OH O-linked oligosaccharides have roles in recognition interaction and enzyme regulation

H O

OH

O

H

HNH

OH

CH2OH

H

C CH3

O

b-D-N-acetylglucosamine

CH2 CH

C

NH

O

H

serine residue

Oligosaccharides that are covalently attached to proteins or to membrane lipids may be linear or branched chains

شكرا الصغائكمد مصطفى طه محمدالفيس بوك

Tahabiochemyahoocomالبريد االلكتروني

• Slide 1
• Carbohydrates
• Slide 3
• Functions
• Slide 5
• Carbohydrates (2)
• Slide 7
• Slide 8
• Simple Carbohydrates
• Monosaccharides
• Slide 11
• Glucose
• Slide 13
• Monosaccharides (2)
• Slide 15
• Sugar Nomenclature
• Slide 17
• D vs L Designation
• Slide 19
• Slide 20
• Slide 21
• Slide 22
• Slide 23
• Enantiomers and epimers
• Slide 25
• Hemiacetal amp hemiketal formation
• Slide 27
• Slide 28
• Rules for drawing Haworth projections
• Rules for drawing Haworth projections (2)
• Slide 31
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Structural representation of sugars
• Slide 38
• Slide 39
• Simple Carbs
• Slide 41
• Slide 42
• Slide 43
• Rules for drawing Haworth projections (3)
• Optical isomerism
• POLARIMETRY
• polarimetry
• Slide 48
• Slide 49
• Slide 50
• Specific rotation of various carbohydrates at 20oC
• Slide 52
• Slide 53
• Glucose oxidase
• Reduction
• Slide 56
• Glycosidic Bonds
• Slide 58
• Slide 59
• Sugar derivatives
• Sugar derivatives (2)
• Slide 62
• Slide 63
• Slide 64
• Slide 65
• Slide 66
• SUCROSE
• Slide 68
• Slide 69
• Slide 70
• Slide 71
• Oligosaccharides
• Slide 73
• Slide 74
• Slide 75
• Starches
• Starch
• Slide 78
• Slide 79
• Slide 80
• Slide 81
• Cellulose
• Slide 83
• Oligosaccharides (2)
• Slide 85
• Slide 86
• Glycogen
• Slide 88
• Slide 89
• Slide 90
• Slide 91

Glycogen

bull also known as animal starchbull stored in muscle and liver (mostly)bull present in cells as granules (high MW)bull contains both (14) links and (16) branches at

every 8 to 12 glucose unit (more frequent than in starch)

bull complete hydrolysis yields glucosebull glycogen and iodine gives a red-violet colorbull hydrolyzed by both and b-amylases and by

glycogen phosphorylase

A portion of the structure of heparin

Heparin is a carbohydrate with anticoagulant properties It is used in bloodbanks to prevent clotting and in the prevention of blood clots in patients recovering from serious injury or surgery

Numerous derivatives of heparin have been made (LMWH enoxaparin (Lovenox) dalteparin (Fragmin) tinzaparin (Innohep) fondaparinux

Honey also contains glucose and fructose along withsome volatile oils

O-linked oligosaccharide chains of glycoproteins vary in complexity They link to a protein via a glycosidic bond between a sugar residue amp a serine or threonine OH O-linked oligosaccharides have roles in recognition interaction and enzyme regulation

H O

OH

O

H

HNH

OH

CH2OH

H

C CH3

O

b-D-N-acetylglucosamine

CH2 CH

C

NH

O

H

serine residue

Oligosaccharides that are covalently attached to proteins or to membrane lipids may be linear or branched chains

شكرا الصغائكمد مصطفى طه محمدالفيس بوك

Tahabiochemyahoocomالبريد االلكتروني

• Slide 1
• Carbohydrates
• Slide 3
• Functions
• Slide 5
• Carbohydrates (2)
• Slide 7
• Slide 8
• Simple Carbohydrates
• Monosaccharides
• Slide 11
• Glucose
• Slide 13
• Monosaccharides (2)
• Slide 15
• Sugar Nomenclature
• Slide 17
• D vs L Designation
• Slide 19
• Slide 20
• Slide 21
• Slide 22
• Slide 23
• Enantiomers and epimers
• Slide 25
• Hemiacetal amp hemiketal formation
• Slide 27
• Slide 28
• Rules for drawing Haworth projections
• Rules for drawing Haworth projections (2)
• Slide 31
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Structural representation of sugars
• Slide 38
• Slide 39
• Simple Carbs
• Slide 41
• Slide 42
• Slide 43
• Rules for drawing Haworth projections (3)
• Optical isomerism
• POLARIMETRY
• polarimetry
• Slide 48
• Slide 49
• Slide 50
• Specific rotation of various carbohydrates at 20oC
• Slide 52
• Slide 53
• Glucose oxidase
• Reduction
• Slide 56
• Glycosidic Bonds
• Slide 58
• Slide 59
• Sugar derivatives
• Sugar derivatives (2)
• Slide 62
• Slide 63
• Slide 64
• Slide 65
• Slide 66
• SUCROSE
• Slide 68
• Slide 69
• Slide 70
• Slide 71
• Oligosaccharides
• Slide 73
• Slide 74
• Slide 75
• Starches
• Starch
• Slide 78
• Slide 79
• Slide 80
• Slide 81
• Cellulose
• Slide 83
• Oligosaccharides (2)
• Slide 85
• Slide 86
• Glycogen
• Slide 88
• Slide 89
• Slide 90
• Slide 91

A portion of the structure of heparin

Heparin is a carbohydrate with anticoagulant properties It is used in bloodbanks to prevent clotting and in the prevention of blood clots in patients recovering from serious injury or surgery

Numerous derivatives of heparin have been made (LMWH enoxaparin (Lovenox) dalteparin (Fragmin) tinzaparin (Innohep) fondaparinux

Honey also contains glucose and fructose along withsome volatile oils

O-linked oligosaccharide chains of glycoproteins vary in complexity They link to a protein via a glycosidic bond between a sugar residue amp a serine or threonine OH O-linked oligosaccharides have roles in recognition interaction and enzyme regulation

H O

OH

O

H

HNH

OH

CH2OH

H

C CH3

O

b-D-N-acetylglucosamine

CH2 CH

C

NH

O

H

serine residue

Oligosaccharides that are covalently attached to proteins or to membrane lipids may be linear or branched chains

شكرا الصغائكمد مصطفى طه محمدالفيس بوك

Tahabiochemyahoocomالبريد االلكتروني

• Slide 1
• Carbohydrates
• Slide 3
• Functions
• Slide 5
• Carbohydrates (2)
• Slide 7
• Slide 8
• Simple Carbohydrates
• Monosaccharides
• Slide 11
• Glucose
• Slide 13
• Monosaccharides (2)
• Slide 15
• Sugar Nomenclature
• Slide 17
• D vs L Designation
• Slide 19
• Slide 20
• Slide 21
• Slide 22
• Slide 23
• Enantiomers and epimers
• Slide 25
• Hemiacetal amp hemiketal formation
• Slide 27
• Slide 28
• Rules for drawing Haworth projections
• Rules for drawing Haworth projections (2)
• Slide 31
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Structural representation of sugars
• Slide 38
• Slide 39
• Simple Carbs
• Slide 41
• Slide 42
• Slide 43
• Rules for drawing Haworth projections (3)
• Optical isomerism
• POLARIMETRY
• polarimetry
• Slide 48
• Slide 49
• Slide 50
• Specific rotation of various carbohydrates at 20oC
• Slide 52
• Slide 53
• Glucose oxidase
• Reduction
• Slide 56
• Glycosidic Bonds
• Slide 58
• Slide 59
• Sugar derivatives
• Sugar derivatives (2)
• Slide 62
• Slide 63
• Slide 64
• Slide 65
• Slide 66
• SUCROSE
• Slide 68
• Slide 69
• Slide 70
• Slide 71
• Oligosaccharides
• Slide 73
• Slide 74
• Slide 75
• Starches
• Starch
• Slide 78
• Slide 79
• Slide 80
• Slide 81
• Cellulose
• Slide 83
• Oligosaccharides (2)
• Slide 85
• Slide 86
• Glycogen
• Slide 88
• Slide 89
• Slide 90
• Slide 91

Honey also contains glucose and fructose along withsome volatile oils

O-linked oligosaccharide chains of glycoproteins vary in complexity They link to a protein via a glycosidic bond between a sugar residue amp a serine or threonine OH O-linked oligosaccharides have roles in recognition interaction and enzyme regulation

H O

OH

O

H

HNH

OH

CH2OH

H

C CH3

O

b-D-N-acetylglucosamine

CH2 CH

C

NH

O

H

serine residue

Oligosaccharides that are covalently attached to proteins or to membrane lipids may be linear or branched chains

شكرا الصغائكمد مصطفى طه محمدالفيس بوك

Tahabiochemyahoocomالبريد االلكتروني

• Slide 1
• Carbohydrates
• Slide 3
• Functions
• Slide 5
• Carbohydrates (2)
• Slide 7
• Slide 8
• Simple Carbohydrates
• Monosaccharides
• Slide 11
• Glucose
• Slide 13
• Monosaccharides (2)
• Slide 15
• Sugar Nomenclature
• Slide 17
• D vs L Designation
• Slide 19
• Slide 20
• Slide 21
• Slide 22
• Slide 23
• Enantiomers and epimers
• Slide 25
• Hemiacetal amp hemiketal formation
• Slide 27
• Slide 28
• Rules for drawing Haworth projections
• Rules for drawing Haworth projections (2)
• Slide 31
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Structural representation of sugars
• Slide 38
• Slide 39
• Simple Carbs
• Slide 41
• Slide 42
• Slide 43
• Rules for drawing Haworth projections (3)
• Optical isomerism
• POLARIMETRY
• polarimetry
• Slide 48
• Slide 49
• Slide 50
• Specific rotation of various carbohydrates at 20oC
• Slide 52
• Slide 53
• Glucose oxidase
• Reduction
• Slide 56
• Glycosidic Bonds
• Slide 58
• Slide 59
• Sugar derivatives
• Sugar derivatives (2)
• Slide 62
• Slide 63
• Slide 64
• Slide 65
• Slide 66
• SUCROSE
• Slide 68
• Slide 69
• Slide 70
• Slide 71
• Oligosaccharides
• Slide 73
• Slide 74
• Slide 75
• Starches
• Starch
• Slide 78
• Slide 79
• Slide 80
• Slide 81
• Cellulose
• Slide 83
• Oligosaccharides (2)
• Slide 85
• Slide 86
• Glycogen
• Slide 88
• Slide 89
• Slide 90
• Slide 91

O-linked oligosaccharide chains of glycoproteins vary in complexity They link to a protein via a glycosidic bond between a sugar residue amp a serine or threonine OH O-linked oligosaccharides have roles in recognition interaction and enzyme regulation

H O

OH

O

H

HNH

OH

CH2OH

H

C CH3

O

b-D-N-acetylglucosamine

CH2 CH

C

NH

O

H

serine residue

Oligosaccharides that are covalently attached to proteins or to membrane lipids may be linear or branched chains

شكرا الصغائكمد مصطفى طه محمدالفيس بوك

Tahabiochemyahoocomالبريد االلكتروني

• Slide 1
• Carbohydrates
• Slide 3
• Functions
• Slide 5
• Carbohydrates (2)
• Slide 7
• Slide 8
• Simple Carbohydrates
• Monosaccharides
• Slide 11
• Glucose
• Slide 13
• Monosaccharides (2)
• Slide 15
• Sugar Nomenclature
• Slide 17
• D vs L Designation
• Slide 19
• Slide 20
• Slide 21
• Slide 22
• Slide 23
• Enantiomers and epimers
• Slide 25
• Hemiacetal amp hemiketal formation
• Slide 27
• Slide 28
• Rules for drawing Haworth projections
• Rules for drawing Haworth projections (2)
• Slide 31
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Structural representation of sugars
• Slide 38
• Slide 39
• Simple Carbs
• Slide 41
• Slide 42
• Slide 43
• Rules for drawing Haworth projections (3)
• Optical isomerism
• POLARIMETRY
• polarimetry
• Slide 48
• Slide 49
• Slide 50
• Specific rotation of various carbohydrates at 20oC
• Slide 52
• Slide 53
• Glucose oxidase
• Reduction
• Slide 56
• Glycosidic Bonds
• Slide 58
• Slide 59
• Sugar derivatives
• Sugar derivatives (2)
• Slide 62
• Slide 63
• Slide 64
• Slide 65
• Slide 66
• SUCROSE
• Slide 68
• Slide 69
• Slide 70
• Slide 71
• Oligosaccharides
• Slide 73
• Slide 74
• Slide 75
• Starches
• Starch
• Slide 78
• Slide 79
• Slide 80
• Slide 81
• Cellulose
• Slide 83
• Oligosaccharides (2)
• Slide 85
• Slide 86
• Glycogen
• Slide 88
• Slide 89
• Slide 90
• Slide 91

شكرا الصغائكمد مصطفى طه محمدالفيس بوك

Tahabiochemyahoocomالبريد االلكتروني

• Slide 1
• Carbohydrates
• Slide 3
• Functions
• Slide 5
• Carbohydrates (2)
• Slide 7
• Slide 8
• Simple Carbohydrates
• Monosaccharides
• Slide 11
• Glucose
• Slide 13
• Monosaccharides (2)
• Slide 15
• Sugar Nomenclature
• Slide 17
• D vs L Designation
• Slide 19
• Slide 20
• Slide 21
• Slide 22
• Slide 23
• Enantiomers and epimers
• Slide 25
• Hemiacetal amp hemiketal formation
• Slide 27
• Slide 28
• Rules for drawing Haworth projections
• Rules for drawing Haworth projections (2)
• Slide 31
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Structural representation of sugars
• Slide 38
• Slide 39
• Simple Carbs
• Slide 41
• Slide 42
• Slide 43
• Rules for drawing Haworth projections (3)
• Optical isomerism
• POLARIMETRY
• polarimetry
• Slide 48
• Slide 49
• Slide 50
• Specific rotation of various carbohydrates at 20oC
• Slide 52
• Slide 53
• Glucose oxidase
• Reduction
• Slide 56
• Glycosidic Bonds
• Slide 58
• Slide 59
• Sugar derivatives
• Sugar derivatives (2)
• Slide 62
• Slide 63
• Slide 64
• Slide 65
• Slide 66
• SUCROSE
• Slide 68
• Slide 69
• Slide 70
• Slide 71
• Oligosaccharides
• Slide 73
• Slide 74
• Slide 75
• Starches
• Starch
• Slide 78
• Slide 79
• Slide 80
• Slide 81
• Cellulose
• Slide 83
• Oligosaccharides (2)
• Slide 85
• Slide 86
• Glycogen
• Slide 88
• Slide 89
• Slide 90
• Slide 91