Following amino acid form an integral part of collagen synthesis:

Ans: A (Lysine) Ref: Harpers illustrated Biochemistry. 28th editionExplanation:CollagenCollagen is a fibrous proteinMost abundant structural proteinAccounts for 25% of the total body proteinsFound in skin, joints, skeleton, tendons, cartilage, cornea and blood vesselsUnusual right-handed triple helix3 polypeptide chains, an unusual amino acid composition33% glycine, 10% proiine, 10% hydroxyproline (Hyp)The sequence Gly-X-Y-Gly-X-Y is repetitiveHvdroxylated amino acid (pro, lys)characteristic of collagenSynthesized post- translationally. a step requiring vitamin C.Vitamin C deficiency symptoms explained by- disturbances in collagen biosynthesis.Collagen molecules tend to associate with one another to form larger, more complex cylindrical fibrils (diameter 20-500nm)At either end. the individual collagen molecules are cross-linked via modified lysine residues.This gives tensile strength to collagenExtent of cross-linking increases with age