title: Concomitant hydroxylation of proline and lysine residues in collagen using purified enzymes in vitro.
abstract: Concomitant hydroxylation of proline and lysine residues in protocollagen was studied using purified enzymes. The data suggest that prolyl 4-hydroxylase (prolyl-glycyl-peptide, 2-oxoglutarate: oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2) and lysyl hydroxylase (peptidyllysine, 2-oxoglutarate; oxygen 5-oxidoreductase, EC 1.14.11.4) are competing for the protocollagen substrate, this competition resulting in an inhibition of the lysyl hydroxylase but not of the prolyl 4-hydroxylase reaction. When the same protocollagen was used for these hydroxylases, the affinity of prolyl 4-hydroxylase to the protocollagen substrate was about 2-fold higher than that of lysyl hydroxylase. Hydroxylation of lysine residues in protocollagen had no effect on the affinity of prolyl 4-hydroxylase, whereas hydroxylation of proline residues decreased the affinity of lysyl hydroxylase to one-half of the value determined before the hydroxylation. When enzyme preparations containing different ratios of lysyl hydroxylase activity to prolyl 4-hydroxylase activity were used to hydroxylase protocollagen substrate, it was found that in the case of a low ratio the hydroxylation of lysine residues seemed to proceed only after a short lag period. Accordingly, it seems probable that most proline residues are hydroxylated to 4-hydroxyproline residues before hydroxylation of lysine residues if the prolyl 4-hydroxylase and lysyl hydroxylase are present as free enzymes competing for the same protocollagen substrate.
mesh_terms: D000818:Animals; D002642:Chick Embryo; D003094:Collagen / Q000096:biosynthesis*; D006900:Hydroxylation; D007700:Kinetics; D008239:Lysine / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D011347:Procollagen / Q000378:metabolism*; D008240:Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase / Q000302:isolation & purification / Q000378:metabolism*; D011393:Procollagen-Proline Dioxygenase / Q000302:isolation & purification / Q000378:metabolism*; D011392:Proline / Q000378:metabolism*; D013710:Tendons
chemical_list: D011347:Procollagen; D003094:Collagen; D011392:Proline; D006899:Mixed Function Oxygenases; D011393:Procollagen-Proline Dioxygenase; D008240:Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase; D008239:Lysine