Differences in P-450 Cytochromes from Livers of Rats Treated with Phenobarbital and with 3-Methylcholanthrene

• Published in: The Journal of biological chemistry Vol. 248; no. 6; pp. 2192 - 2201
• Main Authors: Fujita, T, Shoeman, D W, Mannering, G J
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 25.03.1973
• Subjects: Ammonium Sulfate; Animals; Chromatography, DEAE-Cellulose; Cytochrome P-450 Enzyme System - metabolism; Cytochrome Reductases - metabolism; Drug Synergism; Glycerol - pharmacology; Hemeproteins - metabolism; Hydrogen-Ion Concentration; Liver - cytology; Liver - drug effects; Liver - enzymology; Liver - metabolism; Male; Methylcholanthrene - pharmacology; Microsomes, Liver - drug effects; Microsomes, Liver - enzymology; Microsomes, Liver - metabolism; Oxidation-Reduction; Phenobarbital - pharmacology; Rats; Spectrophotometry; Spectrophotometry, Ultraviolet; Subcellular Fractions - metabolism; Surface-Active Agents - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)44204-X

Soluble P-450 cytochromes were obtained from hepatic microsomes from rats treated with either phenobarbital or 3-methylcholanthrene using the nonionic detergent action of Triton N-101 and the stabilizing effect of glycerol. Ammonium sulfate fractionation, DEAE-cellulose column chromatography, and alumina gel-Cγ adsorption were employed to give concentrations of cytochrome P-450 from phenobarbital-treated rats, and cytochrome P 1 -450 from 3-methyl-cholanthrene-treated rats, about 4-fold greater than those seen in the microsomes from which the preparations were derived. The spectral characteristics of cytochrome P-450 and P 1 -450 were very similar, but both qualitative and quantitative differences were observed. Differences were also observed in their carbon monoxide and ethyl isocyanide difference spectra. Type I and type II drug-binding spectra were seen with the solubilized cytochrome P-450, but cytochrome P 1 -450 gave only the type II binding spectrum. The absolute spectrum of oxidized cytochrome P 1 -450, and studies which employed tritiated 3-methylcholanthrene, showed that cytochrome P 1 -450 is not a complex of 3-methylcholanthrene or its metabolites with cytochrome P-450.