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Yulia Suciati

METABOLISM

OF AMINO ACIDS

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OVERVIEW OF AMINO ACID METABOLISM

ENVIRONMENT ORGANISM

Ingested

protein

Bio-

synthesisProtein

AMINOACIDS

NitrogenCr!on

s"e#etons

$re

Degradation

(required)

12 3

a

b

PurinesPyrimidinesPorphyrins

c c

Used for

energypyrua!e"#$e!o%&u!ara!esucciny'oA(umara!eo)a&oace!a!e

ace!oace!a!eace!y& 'oA

*glucogenic)(ketogenic)

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NITROGEN +A,AN'E

Ni!ro%en ba&ance - ni!ro%en in%es!ed # ni!ro%en e)cre!ed

*primari&y as pro!ein. *primari&y as urea.

Ni!ro%en ba&ance - / *nitrogen equilibrium)

pro!ein syn!hesis - pro!ein de%rada!ion

Posi!ie ni!ro%en ba&ance

pro!ein syn!hesis 0 pro!ein de%rada!ion

Ne%a!ie ni!ro%en ba&ance

pro!ein syn!hesis pro!ein de%rada!ion

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N balance = NN balance = Ninin

- N- Noutout

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Positive Nitrogen BalancePositive Nitro

gen Balance

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Negative Nitrogen BalanceNegative Nitrogen Balance

1. Stress

2. Decreased Intake

3. Lack of an essential AA

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Metabolic Pool of Amino AcidsMetabolic Pool of Amino Acids

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A%ino A&id Re'(ire%ents o) *(%ns

--------------------------------------------------------------------N(trition##y Essenti# N(trition##y Nonessenti#

--------------------------------------------------------------------Ar%inine

a A&anine

is!idine Aspara%ine

Iso&eucine Aspar!a!e

,eucine 'ys!eine

,ysine G&u!ama!e

Me!hionine G&u!amine

Pheny&a&anine G&ycine

Threonine Pro&ine

Tryp!ophan Serine

Va&ine Tyrosine

---------------------------------------------------------------------a Nu!ri!iona&&y semiessen!ia&45 Syn!hesi6ed a! ra!es

inade7ua!e !o suppor! %ro8!h o( chi&dren4

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Glucose-alanine cycle

Alais the carrier of ammonia and of the carbon

skeleton of yru!ate from muscle to li!er.

"he ammonia is e#creted and the yru!ate is

used to roduce $lucose% &hich is returned to

the muscle.

Alaninelays a secial role in

transortin$ amino $rous to li!er.

Accordin% !o 94 ,4 Ne&son: M4 M4 'o) ;,ENINGER4 PRIN'IP,ES O< +IO'EMISTR=

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"he fate of the amino $rou durin$ amino acid catabolism

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'linicaly imortant transaminases

ALT

Alanine--keto$lutarate transferase ALT(also called glutamate-pyru!ate transaminase ) GPT*

Asartate--keto$lutarate transferase AST

(also called glutamate-o#alacetate transferase ) GOT*

Imortant in the dia$nosis of heart and li!er dama$e caused by heart

attack% dru$ to#icity% or infection.

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>REA '=',E

mi!ochondriacy!oso&

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Metabolism of some

selected amino acids

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+istidine ,etabolism

+istamine ormation

N

N

HCH2CHCO2

-

NH3

+

N

N

HCH2CH2NH2

+istidine +istamine

+istidine

decarbo#ylase

CO2

+istamine

Synthesi/ed in and released by mast cells,ediator of aller$ic resonse !asodilation%

bronchoconstriction

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Glycine o#idation to '02

Glycine roduced from serine or from the diet can also be o#idi/ed by $lycine

decarbo#ylase (also referred to as the $lycine clea!a$e comle#% G''* to yield a

second eui!alent of N%N1-methylene-tetrahydrofolate as &ell as ammonia and

'02.

'opy (romhttp://themedicalbiochemistrypage.org/amino-acid-metabolism.html

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Aromatic

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Aromatic

Amino

Acids

Phenylalanine Tyrosine Tryptophane

fumarate Aceto

acetate

Dopa &

Dopamine Melanine

Nor

epinephrin

&

epinephrine

Thyroxin

Satol &

!ndol Melatonin

Anthranilic Serotoninglucose etone

Alanine Nicotinamide

Acetoacetyl

"oA

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4iosynthesis of "yrosinefrom 5henylalanine

5henylalanine hydro#ylase is a mi#ed-function o#y$enase one atom of o#y$en is

incororated into &ater and the other into the hydro#yl of tyrosine. "he reductant is the

tetrahydrofolate-related cofactor tetrahydro#iopterin% &hich is maintained in the reduced

state by the 6AD+-deendent en/yme dihydroteridine reductase

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$yperphenylalaninemia - comlete deficiency of henylalaninehydro#ylase (lasma le!el of 5he raises from normal . to 2 m$7dL to

more than 2 m$7dL*.

"he mental retardation is caused by the accumulation of

henylalanine% &hich becomes a ma8or donor of amino $rous in

aminotransferase acti!ity and deletes neural tissue of 9-keto$lutarate.

Absence of 9-keto$lutarate in the brain shuts do&n the "'A cycle and

the associated roduction of aerobic ener$y% &hich is essential to

normal brain de!eloment.

6e&borns are routinelly tested for blood concentration of 5he.

"he diet &ith lo&-henylalanine diet.

Phenylketonuria

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A,AM9>,I,,A

SEMOGA +ERMAN