title: Oxidation of pyrazole by reconstituted systems containing cytochrome P-450 IIE1.
abstract: Rat liver microsomes oxidize pyrazole to 4-hydroxypyrazole and this oxidation is increased in microsomes isolated from rats treated with inducers of cytochrome P-450 IIE1, such as pyrazole or ethanol. A reconstituted system containing the P-450 IIE1, purified from pyrazole-treated rats, oxidized pyrazole to 4-hydroxypyrazole in a time- and P-450-dependent manner. Oxidation of pyrazole was dependent on the concentration of pyrazole over the range of 0.15 mM to 1.0 mM. In isolated microsomes, glycerol inhibited pyrazole oxidation by about 50% under concentration conditions which occur in the reconstituted system; hence, the values for pyrazole oxidation by the reconstituted systems are underestimated because of the presence of glycerol. Oxidation of pyrazole was inhibited by competitive substrates for P-450 IIE1, such as 4-methylpyrazole, aniline and ethanol, as well as by an antibody raised against the pyrazole-induced P-450 IIE1. Thus, pyrazole is an effective substrate for oxidation by purified P-450 IIE1, extending the substrate specificity of this isozyme to potent inhibitors of alcohol dehydrogenase.
authors.affiliation: Department of Biochemistry, Mount Sinai School of Medicine, New York, NY.
authors.forename: L A
authors.initials: LA
authors.lastname: Clejan
authors.forename: A I
authors.initials: AI
authors.lastname: Cederbaum
mesh_terms: D000426:Alcohol Dehydrogenase / Q000037:antagonists & inhibitors; D000814:Aniline Compounds / Q000494:pharmacology; D000906:Antibodies; D001667:Binding, Competitive; D003577:Cytochrome P-450 Enzyme System / Q000276:immunology / Q000378:metabolism*; D004790:Enzyme Induction / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology; D000077604:Fomepizole; D005990:Glycerol / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D010084:Oxidation-Reduction; D011720:Pyrazoles / Q000378:metabolism* / Q000494:pharmacology; D013379:Substrate Specificity
chemical_list: D000814:Aniline Compounds; D000906:Antibodies; D007527:Isoenzymes; D011720:Pyrazoles; D000431:Ethanol; C031280:pyrazole; D000077604:Fomepizole; D003577:Cytochrome P-450 Enzyme System; D000426:Alcohol Dehydrogenase; D005990:Glycerol; C023650:aniline