Some of the most important functions of amino acids are as follows:
1. Building blocks of proteins
Only L-amino acids are polymerized to form proteins, though both D-amino acids and non-L-amino acids found in nature.
2. Biological buffers
Amino acids being amphoteric, act as buffers in solutions, resisting changes in pH. They do so by donating H+ ions as pH increases and accepting H+ as pH decreases.
3. Nitrogen storage
Asparagine and glutamine are amide derivatives of as-artic acid and glutamic acid. They serve as storage of nitrogen.
4. Proline forms bands or kinks in polypeptide chains.
5. Cysteine links chains together by forming disulfide bonds.
6. Histidine found in the active site of enzymes where it causes making and breaking of bonds.
7. The aromatic rings of Phe, Tyr and Trp help in electron transfer.
8. Formation of glucose: Some amino acids form glucose by losing amino group.
9. Formation other compounds
(i) Tyrosine produces the hormones thyroxin and adrenaline and the skin pigment melanin,
(ii) Glycine forms heme, and
(iii) Tryptophan produces vitamin, nicotinamide and plant hormone Indole Acetic acid (IAA). The coenzyme A, a vitamin pantothenic acid, coenzyme glutathione and alkaloids are some other compounds formed by amino acids.
10. Antibiotics: The non-protein amino acids are useful compounds of antibiotics e.g. Azaserine, Valinomycin etc.
11. Genetic defects: Inborn errors in the metabolism of amino acids cause several disorders e.g. Phenylketonuria.
12. L-amino acids and their derivatives help in nerve transmission, cell growth and biosynthesis of porphynine, purines, pyrimidines and urea.