Oct 15, 1983

An aryl hydrocarbon hydroxylating hepatic cytochrome P-450 from the marine fish Stenotomus chrysops

Archives of Biochemistry and Biophysics
A V KlotzC Walsh

Abstract

Hepatic microsomal cytochrome P-450 from the untreated coastal marine fish scup, Stenotomus chrysops, was solubilized and resolved into five fractions by ion-exchange chromatography. The major fraction, cytochrome P-450E (Mr = 54,300), was further purified to a specific content of 11.7 nmol heme/mg protein and contained a chromophore absorbing at 447 nm in the CO-ligated, reduced difference spectrum. NH2-terminal sequence analysis of cytochrome P-450E by Edman degradation revealed no homology with any known cytochrome P-450 isozyme in the first nine residues. S. chrysops liver NADPH-cytochrome P-450 reductase, purified 225-fold (Mr = 82,600), had a specific activity of 45-60 U/mg with cytochrome c, contained both FAD and FMN, and was isolated as the one-electron reduced semiquinone. Purified cytochrome P-450E metabolized several substrates including 7-ethoxycoumarin, acetanilide, and benzo[a]pyrene when reconstituted with lipid and hepatic NADPH-cytochrome P-450 reductase from either S. chrysops or rat. The purified, reconstituted monooxygenase system was sensitive to inhibition by 100 microM 7,8-benzoflavone, and analysis of products in reconstitutions with purified rat epoxide hydrolase indicated a preference for oxidation on...Continue Reading

Mentioned in this Paper

Metabolic Process, Cellular
Tumor Promoters
Semiquinone
Stenotomus chrysops
NADPH-Ferrihemoprotein Reductase
Microsomes
Cytochrome P450
Cytochrome P-450 CYP1A2
Chromatography, DEAE-Cellulose
Xenobiotic Monooxygenases

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