Separation of two forms of cytochrome P-450 with aryl hydrocarbon hydroxylase activity from intestinal mucosa microsomes of rabbits treated with 3-methylcholanthrene.
Two forms of cytochrome P-450, designated P-448a and P-448b, were purified from intestinal mucosa microsomes of rabbits treated with 3-methylcholanthrene. Both the cytochromes had absorption maxima at 448 nm in the carbon monoxide-reduced difference spectra. They exhibited comparable catalytic activities with benzo(a)pyrene, 7-ethoxycoumarin, and 7-ethoxyresorufin, when reconstituted with hepatic NADPH-cytochrome c reductase and phosphatidylserine. P-448a was apparently homogeneous on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and its monomeric molecular weight was estimated to be 58,000. The oxidized form had absorption maxima at 416, 512 and 571 nm, indicative of the low spin state. Thus P-448a appeared to be similar to one form of P-450, which was induced in rabbit liver by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). On the other hand, SDS-PAGE of P-448b gave a single major protein band with a monomeric molecular weight of 55,500, indicating that P-448b can be distinguished from P-448a.
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000302:isolation & purification / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000201:enzymology*; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008748:Methylcholanthrene / Q000494:pharmacology; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology*; D011817:Rabbits; D013379:Substrate Specificity
D007527:Isoenzymes; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases