Microsomal benzo(a)pyrene hydroxylase in Aspergillus ochraceus TS: assay and characterization of the enzyme system.
Microsomal preparations of Aspergillus ochraceus TS oxidised benzo(a)pyrene very efficiently in the presence of NADPH and 02 and exhibits a pH optimum of 8.0-8.2. The hydroxylation is also effected in presence of NaI04. Hydroxylation was inhibited by metyrapone, SKF-525A, PCMB, imidazole, carbon monoxide and flavone but not by cyanide, azide and antimycin A indicating thereby the involvement of cytochrome P-450 in this reaction. Inhibition by cytochrome C is consistent with the participation of NADPH-cytochrome C reductase in this hydroxylation. Reduced microsomes and its solubilized preparation, when treated with carbon monoxide, showed absorption maxima at 453 and 449 respectively. Different classical inducers of cytochrome P-450 induce the benzo(a)-pyrene hydroxylase activity to varying degree and as such suggests the existence of multiple forms of cytochrome P-450 in this fungus.
D001189:Aryl Hydrocarbon Hydroxylases / Q000302:isolation & purification*; D001230:Aspergillus / Q000201:enzymology*; D001579:Benzopyrene Hydroxylase / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D055598:Chemical Phenomena; D002621:Chemistry; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D012995:Solubility
D001579:Benzopyrene Hydroxylase; D001189:Aryl Hydrocarbon Hydroxylases; D009251:NADPH-Ferrihemoprotein Reductase