<prompt> Vitamin C is required for -Posttranslational modificationSynthesis of epinephrineTyrosine metabolismAll of the above  <response>: Ans. is d i.e., All of the aboveVitamin C ascorbic acido Ascorbic acid Vitamin C is also called antiscorbutic factor,o It is very heat labile, especially in basic medium,o Ascorbic acid itself is an active form.o Maximum amount of vitamin C is found in adrenal cortex.o Ascorbic acid functions as a reducing agent and scavanger of free radicals antioxidant. Its major functions are :-In collagen synthesis Vitamin C is required for post-translational modification by hydroxylation of proline and lysine residues converting them into hydroxyproline and hydroxylysine. Thus vitamin C is essential for the conversion of procollagen to collagen, which is rich in hydroxyproline and hydroxylysine. Through collagen synthesis, it plays a role in formation of matrix of bone, cartilage, dentine and connective tissue.Synthesis of norepinephrine from dopamine by dopamine-b-monoxygenase dopamine-b-hydroxylase requires Vitamin C.Carnitine synthesisBile acid synthesis :- 7-a-hvdroxylase requires vitamin C.Absorption of iron is stimulated by ascorbic acid by conversion of ferric to ferrous ions.During adrenal steroid synthesis, ascorbic acid is required during hydroxylation reactions.Tyrosine metabolism : - Oxidation of P-hydroxy-phenylpyruvate to homogentisate.Folate metabolism : - Folic acid is converted to its active form tetrahydrofolate by help of Vitamin C. 