All the following biochemical roles of the Ascorbic acid EXCEPT

(Deamination of the hydroxyl group containing amino acids) (134-U.S 3rd) (165-Rana ShindeMetabolic roles and Functions of Ascorbic acid1. Role in cellular Oxidation-Reduction - serving as hydrogen-transport agent2. Role in collagen synthesis - Hydroxy proline and hydroxylysine are important constituents of mature collagen fibres. The are hydroxylated by corresponding "hydroxylases" in presence of vitamin C, Fe++ and molecular O23. Functional activity of Fibroblasts/Osteoblasts - formation of MPS of connective tissue, dentine and intercellular cement substance of capillaries.4. Role in Tryptophan metabolism - as a cofactor for hydroxylation of tryptophan to form 5-OH derivative in the pathway of biosynthesis of serotonin (5-HT)5. Role in Tyrosine metabolism as a cofactor with the enzyme P-OH phenyl pyruvate hydroxylase, which is necessary for hydroxylation and conversion of P-OH phenyl pyruvate to Homogentisic acid (Alkaptonuria)6. Formation of Active FH4 (Tetrahydrofolate) - vitamin-C regulates the conversion of folic acid to folinic acid (so-called citrovorum factor)7. Formation of Ferritin; ATP, NAD+ and NADP+ stimulates the process.8. Absorption of Fe - helps in absorption of Fe in foods. (hypochromic, microcytic anemia)9. Role in electron transport system of mammalian microsomes10. Action on Certain Enzymes-Activation/Inhibition - Arginase and papain are activated, whereas, activity of the enzymes like urease and b-amylase from plants is inhibited11. Role in formation of Catecholamines - as a coenzyme with the enzyme dopamine hydroxylase, which catalyzes the conversion of dopamine to norepinephrine12. Role in formation of Carnitine - Formation of 'carnitine' in liver by hydroxylation by g-butyrobetain13. Role in a-oxidation of fatty acids helps in action of the enzyme a-hydroxylase (a-mono-oxygenase)14. Effect on cholesterol levels - Relation of ascorbic acid with hypocholesterolaemia in man and guinea pigs15. Role in "stress" *The synthesis of bile acids from cholesterol (enzyme-7 a-hydroxylase) is enhanced by ascorbic acid (132-US)16. Vitamin-C has also been reported to act as coenzyme for cathepsins and liver esterases17. Ascorbic acid in both leucocytes and platelets found to be lowered significantly in women taking OCP.18. *Synthesis of corticosteroid hormone - Adrenal gland possess high levels of ascorbic acid, particularly in periods of stress. It is believed that vitamin C is necessary for the hydroxylation reaction in the synthesis of corticosteroid hormone (132-US)19. Sparing action of other vitamins - vitamin C is strong anti-oxidant*. It spares vitamin A, vitamin E, and some B-complex vitamins from oxidation20. Preventive action on cataract - vitamin C reduces the risk of cataract formation* Deamination of the hydroxyl group containing aminoacid requires pyridoxalphosphate