Metabolism of benzo(a)pyrene in the nuclear and microsomal fractions from rhesus monkey liver

The metabolism of benzo(a)pyrene was studied in the nuclear and microsomal fractions from four rhesus monkey livers. The nuclear fraction was obtained by differential centrifugation, including a step in 2.3 M sucrose. The metabolites from 3H-benzo(a)pyrene were separated by high performance liquid chromatography (HPLC) and the radioactivity was measured. The nuclear fraction catalyzed the formation of 4,5- and 7,8-dihydrodiols and that of 9-OH and 3-OH phenols. The ratio between the nuclear and microsomal rate of formation of the metabolites ranged between 0.02 and 0.03. The nuclear fraction did not catalyze the formation of 9,10-dihydrodiol or quinones at a detectable rate. In the microsomal fraction there was a preferential formation of 4,5-dihydrodiol and 3-OH phenol. Nuclei differ from the microsomes for the lack of formation of quinones.