title: Comparison between hepatic and nonhepatic vitamin K-dependent carboxylase.
abstract: Vitamin K-dependent carboxylase is a microsomal enzyme system involved in the carboxylation of protein-bound glutamic acid residues. In mammals, the enzyme is found in many different types of tissue. Hence carboxylated ('Gla-containing') proteins are widely distributed in nature. Neither in vitro nor in vivo differences have been observed with respect to the vitamin K-binding sites of the various carboxylases. Differences between the substrate-binding sites could only be compared after suitable substrates became available. These substrates were prepared from descarboxyprothrombin, osteocalcin and a sperm Gla protein. Substantial differences were detected between the Michaelis constants of various carboxylases for the three substrates mentioned above. It is concluded that vitamin K-dependent carboxylase is a group name for a family of isoenzymes.
mesh_terms: D000818:Animals; D001665:Binding Sites; D015415:Biomarkers; D002135:Calcium-Binding Proteins; D019735:Carbon-Carbon Ligases; D002417:Cattle; D007527:Isoenzymes / Q000378:metabolism; D008025:Ligases / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D015675:Osteocalcin; D011498:Protein Precursors; D011516:Prothrombin / Q000031:analogs & derivatives; D013379:Substrate Specificity; D014018:Tissue Distribution
chemical_list: D015415:Biomarkers; D002135:Calcium-Binding Proteins; D007527:Isoenzymes; D011498:Protein Precursors; D015675:Osteocalcin; C008208:acarboxyprothrombin; D011516:Prothrombin; D008025:Ligases; D019735:Carbon-Carbon Ligases; C020660:glutamyl carboxylase