title: Vitamin K-dependent oxygenase/carboxylase; differential inactivation by sulfhydryl reagents.
abstract: Inhibition of vitamin K-dependent carboxylase and oxygenase by sulfhydryl reagents was compared. Formation of vitamin K epoxide and vitamin K-dependent carboxylation are both strongly (greater than 90%) inhibited by l mM p-hydroxy-mercuribenzoate, and this inhibition is reversed by dithiothreitol. Both activities are also effectively inhibited by N-ethylmaleimide (NEM). Preincubation with vitamin K hydroquinone prevents NEM inhibition of epoxide formation but not of carboxylation. These data argue that separate active sites are required to support vitamin K-dependent epoxide formation and carboxylation and that the binding site vitamin K oxygenase contains an active thiol group.
authors: Department of Biochemistry & Biophysics, Texas Agricultural Experiment Station, College Station.
authors: L M
authors: LM
authors: Canfield
mesh_terms: D019735:Carbon-Carbon Ligases; D004229:Dithiothreitol / Q000494:pharmacology; D004852:Epoxy Compounds / Q000032:analysis; D005033:Ethylmaleimide / Q000494:pharmacology; D007425:Intracellular Membranes / Q000201:enzymology; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D007700:Kinetics; D008025:Ligases / Q000037:antagonists & inhibitors*; D008862:Microsomes, Liver / Q000201:enzymology; D010663:Phenylmercury Compounds / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology*
chemical_list: D004852:Epoxy Compounds; D007461:Iodoacetates; D010663:Phenylmercury Compounds; D013439:Sulfhydryl Reagents; C002910:4-hydroxymercuribenzenesulfonate; D008025:Ligases; D019735:Carbon-Carbon Ligases; C020660:glutamyl carboxylase; D005033:Ethylmaleimide; D004229:Dithiothreitol; D019807:Iodoacetic Acid