Purification of cytochromes P-448 from beta-naphthoflavone-treated rainbow trout.

Rainbow trout were treated with beta-naphthoflavone and the hepatic microsomal cytochrome P-450 solubilized with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Chromatography on tryptamine-Sepharose 4B gave a single cytochrome P-450 peak which was further resolved into three components by elution from DEAE-Sepharose. The two main peaks were then chromatographed on hydroxyapatite and a total of four fractions obtained. Two of these fractions had similar properties and significantly metabolized [14C]benzo[a]pyrene in a reconstituted system containing rat cytochrome P-450 reductase. This activity was inhibited by alpha-naphthoflavone but not by metyrapone of SKF-525A. Purified cytochromes P-448 from 3-methylcholanthrene-treated rat had similar spectral properties and activity towards [14C]benzo[a]pyrene suggesting similarities between these forms.