TY - JOUR T1 - Chromatographic and electrophoretic heterogeneity of the cytochromes P-450 solubilized from untreated rat liver. JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 353 LP - 362 VL - 6 IS - 4 AU - M Warner AU - M V LaMarca AU - A H Neims Y1 - 1978/07/01 UR - http://dmd.aspetjournals.org/content/6/4/353.abstract N2 - When the hepatic microsomes prepared from one or two untreated male rats were incubated for 3 hr at room temperature in buffered Emulgen 911, cholate, glycerol, and EDTA, almost complete recovery of the cytochromes P-450 in solubilized form was obtained. The intact cytochromes P-450 in this preparation were retained by Sephadex G-200. They could be resolved by anion-exchange chromatography into four fractions with 70--80% recovery of cytochrome P-450 and little or no conversion to P-420. In the process, the p-450 hemoproteins were separated from cytochrome b5, NADPH-cytochrome c reductase, and hemoglobulin. Each of the four fractions of cytochrome P-450 could be further resolved by electrofocusing in polyacrylamide into numerous protein bands, more than eight of which stained for heme. Extracts from focused gels retained P-450 spectral character. Mixtures of the various fractions electrofocused additively. Added hematin focused only in the acidic region of the gels. Although these results indicate extensive heterogeneity in the cytochromes P-450, the complexities of electrofocusing in the presence of detergent warrants cautious interpretation. These methods, however, should provide a basis for subsequent chemical, physical, catalytic, and immunological investigations of the heterogeneity, and its significance. ER -