<prompt> Following amino acid form an integral part of collagen synthesis:LysineLeucineArginineGlutamic acid  <response>: 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 HypThe sequence Gly-X-Y-Gly-X-Y is repetitiveHvdroxylated amino acid pro, lyscharacteristic 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 20-500nmAt 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 