Purification and Characterization of Cytochromes P-450 from Liver Microsomes of 3-Methylcholanthrene-Treated Crab-Eating Monkeys1

Two forms of cytochrome P-450 (P-450MC1 and P-450MC2) were purified from liver microsomes of crab-eating monkeys (Macaca irus) treated with 3-methylcholanthrene (MC). Monkey P-450MC1 preparation had a specific content of 14.0 nmol/mg protein and showed a main protein band with a minimum molecular weight of 52,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Monkey P-450MC2 preparation had a specific content of 12.1 nmol/mg protein and a minimum molecular weight of 54,000. The carbon monoxide-reduced difference spectral peaks of monkey P-450MC1 and P-450MC2 were at 448 and 447 nm, respectively. In the reconstituted system, monkey P-450MC2 had high activities for benzo[a]pyrene 3-hydroxylation and 7-ethoxycoumarin O-deethylation. Monkey P-450MC1 had low activities toward these two substrates and a high activity for benzphetamine N-demethylation. Monkey P-450MC1 and P-450MC2 were detected by immunoblotting using an antibody prepared against rat cytochrome P-450c, which is a major form of cytochrome P-450 in liver microsomes of MC-treated rats. These results suggested that the molecular properties of cytochrome P-450 in liver microsomes of crab-eating monkeys treated with MC are similar to those in rats.