Triple helix is found in ?
Ans is 'b' i.e., Collagen Collagen Collegen is the most common protein in the animal world. It is a component of ECM. The collegens are composed of a triple helix of three polypeptide a-chains. It provides tensile strength to tissues. Collegen type IV with laminin is the main component of basement membrane. Fibrillar collegen is synthesized from procollegen. First there is hydroxylation of lysin & proline residues of procollegen. After hydroxylation of lysine and proline residues of procollegen three procollegen chains align in phase to form triple helix. After that oxidation of lysine & hydroxylysine by lysyl oxidase, and proline & hydroxyproline by prolyl oxidase, take place - this results in cross-linking between the chains of adjacent molecules, thus stabilizing the array that is characteristic of collegen. Cross-linking is a major contributor of the tenile strength of collegen. Vit 'c' is required for hydroxylation of lysine & proline residues ofprocollegen - In scurvy (Vit 'c' deficiency) poor wound healing is due to inhibition of this step.
Cystine
Collagen
Pectin
DNA