Stereoselective formation of benzo(c)phenanthrene (+)-(3S,4R) and (+)-(5S,6R)-oxides by cytochrome P450c in a highly purified and reconstituted system.
The principal oxidative metabolites formed from benzo(c)phenanthrene (B(c)Ph) by the cytochromes P450 in liver microsomes from control and treated rats are the 3,4- and 5,6-arene oxides. A procedure is described which allows determination of the enantiomer composition and absolute configuration of these arene oxides based on HPLC separation of isomeric thiolate adducts formed with N-acetyl-L-cysteine in base. Incubation of [3H]-B(c)Ph with highly purified cytochrome P450c in a reconstituted monooxygenase system followed by trapping of the metabolically formed arene oxides as above indicated that the 3,4-oxide was predominantly the (+)-(3S,4R)-enantiomer (90%) and that the 5,6-oxide consisted mainly of the (+)-(5S,6R)-enantiomer (76%). The results are discussed in terms of their implications about the catalytic binding site of cytochrome P450c.
D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008862:Microsomes, Liver / Q000378:metabolism; D009153:Mutagens / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D010616:Phenanthrenes / Q000378:metabolism*; D051381:Rats; D013237:Stereoisomerism
D009153:Mutagens; D010616:Phenanthrenes; C052681:benzo(c)phenanthrene 5,6-oxide; C052691:benzo(c)phenanthrene 3,4-oxide; D003577:Cytochrome P-450 Enzyme System; D009251:NADPH-Ferrihemoprotein Reductase; C002615:benzo(c)phenanthrene