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Trng i hc Dc H Ni

B mn Ha hu c

CHNG 22:

AMINOACID - PEPTID - PROTEIN

i tng dy hc: CQK61

Ngy ging:

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AMINO ACID

+

Amin Acid carboxylic

Th no l amino acid?

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*)nh ngha

- Cha nhm chc amino (NH2)

- Cha nhm chc carboxyl (COOH)

AMINO ACID

Nhm carboxylNhm amino

Mch hydrocarbon

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Phn loi amino acid

O-

O

I H K F E

H3N-CH2-C 2

H3N-CH2-CH2-C 2

1. Theo v tr nhm amino so vi nhm carboxyl

- -amino acid

- -amino acid

H3N-CH2-CH2-CH2-CO2- -amino acid

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2. Theo mch hydrocacbon

Khng phn cc

Phn cc Mang in tch

Mang in tch dng

Mang in tch mI. Amino acid trung tnh

1. Mch thngkhngphncc (Gly, Ala, Val, Leu, Ile)

2 . Mchthngphncc (Ser, Thr, Asn, Gln)

3. Chanhn thm (Phe, Tyr, Trp)4. Cha lu hunh (Cys, Met)

5. Chanhmamin bc 2 (pro)

II. Amino acid c tnh acid (Asp, Glu)

III. Amino acid c tnh base (Lys,Arg, His)

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Amino acid trung tnh

Acid amin khng phn cc

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Amino acid phn cc

Amino acid trung tnh

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Amino acid mang in tch dng

Amino acid c tnh base

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Amino acid mang in tch m

Amino acid c tnh acid

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Danh Php1. Danh php thng thng:

- Xut pht t ngun gc ca hp cht.

- 20 a.a c tm thy khi thy phn protein thin nhin.

+) l cc a.a bc mt

+) nhm amino v tr

Cu trc chung: Trng hp c bit

R CH CO2-

NH3+

E

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Alanin A, Ala

Arginin R, Arg

Asparagin N, Asn

AcidAspartic D, AspCystein C, Cys

Glutamin Q, Gln

Acid glutamic E, GluGlycin G, Gly

Histidin H, His

Isoleucin I, Ile

Leucin L, Leu

Lysin K, Lys

Methionin M, Met

Phenylalanin F, PheProlin P, Pro

Serin S, Ser

Threonin T, ThrTryptophan W, Trp

Tyrosin Y, Tyr

Valin V, Val

- Tn thng dng v k hiu ca 20 a.a c trong protein

thin nhin.

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2. Danh php IUPAC:

Acid + v tr -NH2 + amino + tn HC + oic

VD:

H3C COOH

CH3

NH2

Acid 3-aminobutanoicH3CCOOH

NH2

Acid 2-amino-3-methylpentanoic

Acid -aminobutanoic

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ng Phn

CH3-CH2-CH-COOH

NH2

CH3-C-COOH

NH2

CH3

1. ng phn cu to:

+)ng phn v cu to mch carbon

+)ng phn v v tr nhm amino

VD: Amino acid C4H9NO2 c:

+) Hai ng phn do cu to mch carbon:

+) Ba ng phn v v tr nhm amino

CH3-CH-CH2-COOH

NH2

H2N-CH2-CH-COOH

CH3

CH2-CH2-CH2-COOH

NH2

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2. ng phn quang hc+) Tt c cc a.a trong t nhin (tr glyxin) u c CEbt

i xng.+) Da vo cu hnh Fisher ca glyceraldehyd xc nh

cu trc lp th ca cc aminoacid.

HO OH

H3N+ +NH3

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+) Tt c cc aminoacid trong t nhin u c cu hnh L-

VD:

C trong t nhin Khng c trong t nhin

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+) Cu hnh tng i ca cc a.a c xc nh theo v

tr nhm amino.

COOH

H2N H

C2H5

H CH3

COOH

H NH2

C2H5

H CH3

DL COOH

HO H

CH3

H NH2

D

VD:

..\Bai Tap

\BTdaicuongaa.ppt

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Phng php iu ch

I. Thy phn protein

Protein Hn hp -aminoacidacid hoc

base

1. Phngphp FischerR-CH-COOH

NH2+ C2H5OH

HCl kh R-CH-COOC2H5+NH3

OH -

R-CH-COOC2H5NH2

H2O

OH - (Ag2O)R-CH-COOH

NH2-aminoacid

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2. Phngphp Darkin

Hn hpAminoacid

Alcol benzylic Amino acid 1 nhm

amin, 1 nhm carboxyl

Hn hp -Aminoacid

Cc phng tchphp thch hp

+) Mt s cc phng php tch -Aminoacid

- Dng nc kt tinh -Aminoacid t hoc khng tan trong nc

- Dng thuc th c bit pht hin v tch ring.

- Dng phng php trao i ion.

- Dng phng php sc k.

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II. Phng php tng hp

1. Tng hp cc -Aminoacid1.1. it -halogeno acid(SN)

VD:

H = 65

70%

RCHCOOH

X

RCHCOO H4

H

RCHCOO-

H3+

NH3, d H2O/H+

H2O

NH3+

NH4Br2NH3+

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1.2. it -ceto acid

R C COOH

O

R CH COOHNH

R C COOH

N NHR'

R CH COOH

NH

R C COOH

N OH

R CH COOH

NH

E-cetoacid

NH3

NaBH4

R'NHNH

H NOH

hydrazon

[H]

oxim E-aminoacid

[H]

VD:

H,

OCH3CHCO2H

NH2

CH3CCO2NH3, H2 Pd

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1.3.TnghpStrecker(1850)

RCH

O1)NH3

2) HCN

3) H+, H2O

RCHCO2H

NH2

+) Bc 1:

+) Bc 2:

VD:

NH4Cl

NH2

NH2

1. H2O, HCl, to

2. OH-

NH3+

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VD: Tng hp phenylalanin

NH NHCH3ONa

CH3OH

NHHBr

H2O, toH3N

+

NH3+

- CO2, to

H = 65%

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XC (C 2C2 5)21)N-

2)Na C2 53) X

4) , 2 , heat

C C 2NH2

1.5.Tnghp t KaliPhthalimid(phngphp Gabriel)

- Hiu sut phn ng cao, sn phm d tinh ch

- C th thay th XCH(CO2C2H5)2bngX-R-CO2R

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VD: Tng hp D,L-Phenylalanin

NH

O

O

1) KOH

2) BrCH(CO2C2H5)2

3)-OC2H5

NC(CO2C2H5)2

O

O

-

C6H5CH2Cl

NC(CO2C2H5)2

O

OCH2C6H5

1) H , H2O

2) OH-

C6H5CH2CHCO2H

NH2H = 84 85%

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VD: Tng hp Glycin

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2. Tng hp cc -Aminoacid

2.1. itacid-ethylenic

R CH CH COOH

acidE-ethylenic

ER CH CH COOH

NH

EF

F -aminoacid

NH3

to, p

2.2. italdehyd

R CO

HR CH CH COOH

NH

COOH

CH

COOH

+

NH3

/ROH+ H O + CO

..\Bai Tap\BTC-CHH.ppt

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Tnh cht ha hc

R CH CO2-

NH+

E

R CH CO H

NH2

E

I. Tnh acid - base

Phn ng acid-base ni phn t to thnh ion lng cc

zwitterion (mui ni).

- Cht kt tinh c nhit nng chy cao.

- Khng tan trong dung mi phn cc, tan trong nc.

- Dung dch aminoacid trong nc c momen lng cc cao.

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- Ti pHpKa2, aminoacid cho proton to anion.

Trong dung dch acid

pK1

pK2

Trong dung dch base

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pH thpProton

pH caoanion

im ng in

- Mi trng acid: anion COO- (khng phi NH2) ng vai tr

base nhn proton H+ .

- Mi trng base: cation amonium NH3

+ (khng phi -COOH)

ng vai tr acid cho proton H+ .

- im ng in (pHi): l gi tr pH m ti nng in

lng cc l ln nht. pI.ppt

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-Aa c mch HC (mch bn) l khng ion ho, c pI nm

trong khong 5-6

-Aa c mch HC (mch bn) l ion ho, c tnh acid, c pHinm trong khong 3,2-3,5.

-Aa c mch HC (mch bn) l ion ho, c tnh base, c pHinm trong khong 7,6-10,8

ng dng: S dng pHI tch cc aa (phng php in di).

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..\Bai Tap\BT pI.ppt

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II. Tnh cht ca nhm carboxyl

a a

To mui v nc

To mui phc ni vi cc cation kim loi nng.

1.Phn ng vi base

CuSO4R CH COOH

NH

+

H N

H

HC OO

Cu

OO C

H

HN CH R

R C

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3. Phn ng vi PCl5

2. Phn ng to ester, xc tc acid v c

C C2

' C C '3

2

ClCl

VD:

= 89 92%

3

RH3N CH COClCl-

R

+

5H2N CH COOH + PCl + POCl

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4. Phn ng loi nhm CO2:

II. Tnh cht ca nhm amino

1.Phn ng vi acid v c

- To mui vi acid v c thng thng

-C -COO

2

Cl -C -COO

Cl-

- To hydroxy acid vi acid O2

-C -COO

2

O2-C -COOO 2

enzymH2N CH COOH

R

H2N CH2

R

+ CO2

decarboxydaza

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2.Phn ng alkyl ha.

H2N CH COOH

R

+ R'X H2N CH COOH X-

RR'

+

2N

H2N CH COOH

R

+

imin

R' C O CH COOH

R

NCR'

3. Phn ng to imin

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4.Phn ng acyl ha.

VD:

NH3 CHC 2-

CH2CH(CH3)2

CH3CCl

R'C Cl N CHHH C HR

NH CH C H

RR'C- HClNa H

+

NHCHC 2H

CH2CH(CH3)2

CH3C

(CH3C )2

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5. Phn ng vi Ninhydrin

Xanh tm = 570 nm;co che pu Ninhidrin.ppt

-A.a phn ng vi ninhydrin to phc mu xanh tm, cn gi l

mu tm Ruhemann, hp th nh sng ti = 570nm. Ring prolincho mu vng.

D: Phn ng ninhydrin c d pht hin vt vn tay ngi.

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- Phn ng un nng ca cc amino acid

III. Phn ng c s tham gia ca c hai nhm carboxylv amino.

+) -aminoacid

NH

CH C

NH

C CH R

R

O

O

NH

CH CR

H

OH

O

C CH RHO

HN H

O

- 2H2O

to

+)F-aminoacid dicetopiperazin

R CH CH COOH

HNH2

R CH CH COOH- NH3

to

acidE-ethylenic

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+)K, H, [,-aminoacid

NHC

CH CH2

CH2

O

R

OCCH2CH2CHR

OHHN H

-H2Oto

K-aminoacid K-lactamVD:

+)H-aminoacid

+)[-aminoacid

H-lactam

[-lactam

butyro lactam

NH

C

CH2

CH2

O

CH2- H2O

to

acidK-amino butyric

OCCH2CH2CH2OHHN H

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III. Cc phn ng c bit ca mt s aminoacid.

1.A.a c cha nhn aryl (nhn thm, phn ng Xantoprotein)

- Phn ng ca aminoacid cha nhn aryl vi HNO3 c cho

mu vng do s nitro ha vng benzen.

2.A.a c cha lu hunh

- Phn ng ca cc aminoacid cha lu hunh vi Pb2+/OH-

cho kt ta PbS mu en.

CH2 CH COOH

NH2

HOHNO3

CH2 CH COOH

NH2

HO

O2N

- Sn phm khi cho thm kim vo chuyn thnh mu da cam.

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3.A.a c cha nhn phenol (Phn ng Milon)

- Phn ng ca aminoacid cha nhn phenol vi dung dch

HgNO3 khi un si trong hn hp acid HNO3 v HNO2 cho

kt ta mu nu .

tyrosin: HO CH2 CH COOHNH2

4.A.a c cha vng imidazol (Phn ng Pauli)

-Acid diazobenzosunfonic phn ng vi aminoacid cha vngimidazol trong mi trng kim to hp cht azo c mu

anh o.

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5.A.a c cha vng indol (Phn ng Roxenhen)- Cc aminoacid cha vng indol phn ng vi HCHO 0,1%,

c mt ca HgSO4 cho mu tm.

6. Phn ng di tc dng ca men.

tryptophan:

NH

NH2

COOHCHCH2

- Oxy ha cc a.a bng tc nhn oxy ha hoc enzym to thnh

ceto acid. Sau cetoacid b decacboxyl to thnh aldehyd.

R CH COOHNH2

R C COOHO

(O)

enzy + NH3

E-ami aci E-cet aci

R C COOH

O

-CO2

t+ CO2RCHO

..\Bai Tap\BTC-CHH.ppt

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Amino acid khng phn cc

Amino acid trung tnh

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Amino acid phn cc

Amino acid c tnh base Amino acid c tnh acid

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