Mechanisms of Amino Acids (13 Mechanisms ) | Protein Metabolism

The following points highlight the top thirteen mechanisms of amino acids in body.

1. The amino acids are required for the syn­thesis of protein.

2. These are utilized for the synthesis of me­thionine which is methyl donor. This methyl donor is required for the synthesis of choline, betaine, creatine and epinephrine. Methionine can also be converted into cystine when this amino acid is inad­equately supplied in the diet.

3. Phenylalanine can be converted into ty­rosine and tyrosine is the precursor of epinephrine, thyroxine and the pigment melanin.

4. Glycine, arginine and methionine all par­ticipate in the synthesis of creatine.

5. Glutamine, formed from glutamate, is the chief source of ammonia formation in the kidney. Ammonia helps in the neutraliza­tion of acid to be excreted.

6. Glycine acts as a coupling agent to con­vert benzoic and salicylic acids into hip­puric acid and salicyluric acid, respec­tively, which are readily excreted by the kidney.

7. Histidine can be decarboxylated to pro­duce histamine.

8. Tryptophan can be converted into nico­tinic acid in presence of vitamin B₆ and B₂ and into serotonin which on acetylation and methylation produces the hor­mone melatonin.

9. Glutamate, aspartate and the ammonia formed from amino acids by deamination are utilized for purine and pyrimidine synthesis.

10. Glutamate and aspartate are involved in transamination reaction to form keto ac­ids which are converted into glucose by gluconeogenesis.

11. Alanine, on deamination, forms pyruvic acid which is an important intermediate compound in the metabolism of glucose. The fate of alanine is the same as that of glucose. Hence, alanine can be regarded as a glucose-former.

12. In case the diet contains more proteins than is required to replace the catabolized pro­tein, the excess of amino acids is used for energy production. The presence of an oxi­dative deaminating enzyme system in the liver (and kidney) can convert amino ac­ids into keto acids liberating ammonia in the free state. The ammonia is used for the synthesis of urea.

13. Some of the amino acids are metabolized to glucose derivatives while others form acetoacetate.