PROTEIN METABOLISM

PROTEIN METABOLISM

General Reactions of Aminoacids

 Demination

 Deamidation

 Transamination

 Decarboxylation

TRANSAMINATION

Aminoacid Amino group donor

Keto asit (Product)

Aminoacid (Product) Keto acid Amino group acceptor

Glutamate + α-keto acide α-keto glutarate + α-aminoacid ↔

TRANSAMINASES

 Transamination reactions are controlled by enzymes called transaminases.

 Each transaminase is specific for one or more amino group donors.

 Two important transaminase reactions are catalyzed by alanine aminotransferase (ALT) and aspartate aminotransferase (AST).

Glutamate + Pyruvate ↔ Alanine + alpha keto glutarate

Alanine transaminase (ALT)

https://www.sciencedirect.com/topics/neuroscience/transamination

DEAMINATION

 Deamination of amino acids →→ Formation of the carbon skeletons of

alpha-keto acids

OXİDATIVE DEAMINATION

NAD(P) NAD(P)H + H

Glutamate + H

O Alpha ketoglutarate + NH

L-Aminoacid + O

Alpha ketoacid + NH

+ H

O

L-Aminoacid oxidase

Glutamate dehydrogenase

DEAMIDATION

Glutaminase

Glutamate + NH

Glutamine

DECARBOXYLATION

 Decarboxylation results in carbon dioxide release

 There are many amino acid decarboxylases.

 They convert amino acids into biogenic amines and carbon dioxide.

Histidin →Histamin

Fenil alanin → Dopamin

Tryptophane → Tryptamine

Aspartate → Beta Alanine

Glutamate → GABA

UREA

C O

NH

NH

 It is produced by the liver

 It is transported to the kidneys through the blood

 It is excreted by the urine.

NH

₊ ⁺ 3 ATP + Aspartate

Urea + Fumarate + 2 ADP +AMP + 2Pi + PPi

UREA CYCLE

H

O +

HCO

REFERENCES

Lippincott’s Illustrated Reviews Biochemistry Denise R. Ferrier Series Editor: Richard A. Harvey, 6th Edition https://www.ncbi.nlm.nih.gov/pubmed/22139560