title: Multiple forms of cytochrome P-450 in phenobarbital- and 3-methylcholanthrene-treated rats. Separation and spectral properties.
abstract: Multiple forms of liver microsomal cytochrome P-450 isolated from immature male rats pretreated with phenobarbital or 3-methylcholanthrene are described. Afraction of low specific content (Fraction A. 1.7 TO 4.0 nmol of cytochrome P-450 per mg of protein) and a fraction substantially purified (Fraction B, 9.0 TO 11.0 NMOL of cytochrome P-450 per mg of protein) are obtained by DEAE-cellulose chromatography of a partially purified cytochrome P-450 preparation in the presence of Emulgen 911. Shifts in the absorption maxima in the CO-reduced and ethyl isocyanide difference spectra are observed in the fractions derived from 3-methylcholanthrene-treated rats. The fractions derived from phenobarbital-treated rats exhibit different 455:430 ratios and pH intercepts in the ethyl isocyanide difference spectra. The absolute oxidized spectra and n-octylamine binding spectra at room temperature and EPR analysis at the temperature of liquid helium characterize all the fractions, except the Fraction A from 3-methylcholanthrene-treated rats, as low spin ferric hemeproteins. The A hemeprotein fractions from both 3-methylcholanthrene- and phenobarbital-treated rats have poor catalytic activity for the metabolism of benzphentamine and 3,4-benzo-[a]pyrene in comparison to the B hemeprotein fractions which may be due to the presence of a high concentration of Emulgen 911 in the A fractions. However, the presence of Emulgen 911 cannot account for the spectral differences among the fractions.
mesh_terms: D000588:Amines; D000818:Animals; D001580:Benzopyrenes / Q000378:metabolism; D001589:Benzphetamine / Q000378:metabolism; D002848:Chromatography, DEAE-Cellulose; D003486:Cyanides; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification / Q000378:metabolism*; D006420:Hemeproteins; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology*; D011485:Protein Binding; D011487:Protein Conformation; D051381:Rats; D013053:Spectrophotometry
chemical_list: D000588:Amines; D001580:Benzopyrenes; D003486:Cyanides; D006420:Hemeproteins; D001589:Benzphetamine; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D010634:Phenobarbital