title: Characteristics of the microsomal N-hydroxylation of benzamidine to benzamidoxime.
abstract: 1. A simple and fast h.p.l.c. analysis of benzamidoxime formed by microsomal N-hydroxylation of benzamidine is presented which is well suited for the determination of the N-oxygenation activity of microsomal enzymes. 2. Optimal reaction conditions were determined. The apparent Km and Vmax values were, respectively, 1.61 mM and 0.38 nmol benzamidoxime/min per mg protein. 3. The effects of the inducers phenobarbital, 3-methylcholanthrene and benzamidine itself on hepatic benzamidine metabolizing activity in rabbits were determined. 4. Neither superoxide anion nor hydrogen peroxide is directly involved in the N-hydroxylation reaction. 5. The direct involvement of cytochrome P-450 in the N-hydroxylation of benzamidine is supported by the observation that inhibitors of cytochrome P-450, in particular carbon monoxide, markedly decreased the rate of N-oxygenation.
mesh_terms: D000578:Amidines / Q000378:metabolism*; D000818:Animals; D001550:Benzamidines / Q000378:metabolism*; D002021:Buffers; D002248:Carbon Monoxide / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005260:Female; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism*; D010084:Oxidation-Reduction; D011817:Rabbits; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000578:Amidines; D001550:Benzamidines; D002021:Buffers; D065607:Cytochrome P-450 Enzyme Inhibitors; C053561:benzamidoxime; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System; D002374:Catalase; D013482:Superoxide Dismutase; C032157:benzamidine