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Collagen Biosynthesis

Discussion

  • biosynthesis of collagen is initiated w/ osteoblasts;
  • these intracellular events involve protein synthesis on endoplasmic reticulum to form 3 polypeptide chains, which make up protocollagen;
  • protocollagen is hydroxylated to form procollagen, which is glyco-sylated at the endoplasmic reticulum;
    • degree of hydroxylation of the lysine residue is important in that it will determine the number of crosslinks and therefore strength of the
      collagen;
  • procollagen is converted to a triple helix before secretion from cell by microtubules;
  • procollagen helices are actually longer than collagen molecules owing to amino-terminal and carboxy-terminal endpieces that keep collagen
    soluble while inside the cell;

    • intracellular processes require more than eight enzymes, result in over l50 modifications of each chain, and alter one-tenth of the amino acids;
  • once the osteoblasts secretes procollagen, a procollagen peptidase splits off the terminal endpieces, and polymerization and maturation
    naturally follow;
  • covalent bonds are formed between the adjacent collagen molecules both within microfibrils and between adjacent microfibrils;
    • these crosslinks determine maximal tensile strength of tissue collagen & its subsequent solubility and thus extractability