Specificity of hepatic cytochrome P-450 isoenzymes from PCB-treated rats and participation of cytochrome b5 in the activation of aflatoxin B1.
Employing six forms of cytochrome P-450s fractionated from the hepatic microsomes of PCB-treated rats, the activation of aflatoxin B1 (AFB1) was examined in the reconstituted cytochrome P-450 system. AFB1 was specifically activated into DNA-binding form by cytochrome P-450 I-a, which is one of P-450 type cytochromes and possesses an absorption peak at 450.0 nm in its carbon monoxide difference spectrum. This activation was enhanced by cytochrome b5 and the maximal enhancement (1.6-fold of the control) was observed with the molar ratio of 0.25 cytochrome b5:1.0 cytochrome P-450.
D016604:Aflatoxin B1; D000348:Aflatoxins / Q000378:metabolism* / Q000633:toxicity; D000818:Animals; D001711:Biotransformation; D002273:Carcinogens / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D003573:Cytochrome b Group / Q000378:metabolism*; D015786:Cytochromes b5; D007527:Isoenzymes / Q000235:genetics*; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D009152:Mutagenicity Tests; D009153:Mutagens; D009154:Mutation; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D051381:Rats; D012486:Salmonella typhimurium
D000348:Aflatoxins; D002273:Carcinogens; D003573:Cytochrome b Group; D007527:Isoenzymes; D009153:Mutagens; D015786:Cytochromes b5; D003577:Cytochrome P-450 Enzyme System; D016604:Aflatoxin B1; D011078:Polychlorinated Biphenyls