title: Prolyl 3-hydroxylase: partial characterization of the enzyme from rat kidney cortex.
abstract: The formation of 3-hydroxyproline was studied with crude rat kidney cortex extract as a source of enzyme and chick embryo tendon protocollagen and procollagen or cartilage protocollagen as a substrate. Synthesis of 3-hydroxyproline was observed with all these substrates and the formation of 3-hydroxyproline ranged up to seven residues per pro-alpha-chain. The highest rate of 3-hydroxylation took place at 20 degrees C and the reaction required Fe2+, O2,2-oxoglutarate and ascorbate. The formation of 3-hydroxyproline was affected by chain length and the conformation of the substrate, in that longer polypeptide chains proved better substrates, while the native triple-helical conformation of protocollagen or procollagen completely prevented the reaction. Formation of 3-hydroxyproline with tendon procollagen as a substrate was not inhibited by antiserum to prolyl 4-hydroxylase or by poly(L-proline) when these substances were used in concentrations which clearly inhibited 4-hydroxyproline formation with tendon protocollagen as a substrate. Furthermore, pure prolyl 4-hydroxylase did not synthesize any 3-hydroxyproline under conditions in which the crude rat kidney cortex enzyme would readily do so. The data thus strongly suggest that prolyl 3-hydroxylase and prolyl 4-hydroxylase are separate enzymes.
mesh_terms: D000818:Animals; D002642:Chick Embryo; D007672:Kidney Cortex / Q000201:enzymology*; D007700:Kinetics; D010446:Peptide Fragments / Q000032:analysis; D011347:Procollagen; D011393:Procollagen-Proline Dioxygenase / Q000378:metabolism*; D011487:Protein Conformation; D051381:Rats; D013329:Structure-Activity Relationship; D013696:Temperature; D013710:Tendons
chemical_list: D010446:Peptide Fragments; D011347:Procollagen; D011393:Procollagen-Proline Dioxygenase