title: p-Nitrophenyl vinyl ether, a novel substrate for the assay of cytochrome P-450 dependent olefinic epoxidation in hepatic microsomes.
abstract: p-Nitrophenyl vinyl ether (NPVE) was metabolized to p-nitrophenol and glycolaldehyde via an epoxide by rat hepatic microsomes. The cofactor requirement and effects of monooxygenase inhibitors indicated that the oxidative metabolism of NPVE was mediated by microsomal cytochrome P-450. Epoxide hydrolase plays a minor role, because a strong epoxide hydrolase inhibitor, 3,3,3-trichloropropene oxide, showed a weak inhibitory effect on the p-nitrophenol formation. The epoxy intermediate is so labile that the hydrolysis of the epoxide proceeds mostly nonenzymically even at a neutral pH. Induction experiments suggested that NPVE was susceptible to a wide varieties of cytochrome P-450 species. Thus, a convenient and sensitive method for the assay of olefinic epoxidase activity in hepatic microsomes was developed with NPVE as a substrate.
mesh_terms: D000818:Animals; D003124:Colorimetry; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity; D014753:Vinyl Compounds / Q000378:metabolism*
chemical_list: D004852:Epoxy Compounds; D014753:Vinyl Compounds; D003577:Cytochrome P-450 Enzyme System; C047678:(4-nitrophenyl)vinyl ether; D006899:Mixed Function Oxygenases