title: The 14 alpha-demethylation of obtusifoliol by a cytochrome P-450 monooxygenase from higher plants' microsomes.
abstract: Microsomes isolated from corn embryos (Zea mays) can demethylate the 14 alpha-methyl group of obtusifoliol 2. An enzymatic assay has been developed for obtusifoliol 14 alpha-methyl-demethylase in higher plants. The enzymatic reaction was shown to occur sequentially, converting obtusifoliol 2 to 4 alpha-methyl-5 alpha-ergosta-8,24(28)-dien-3 beta-ol 4 via the trienol 4 alpha-methyl-5 alpha-ergosta-8,14,24(28)-trien-3 beta-ol 3 which was thoroughly identified. This enzymatic reaction is dependent of NADPH and molecular oxygen. It is inhibited by CO, menadione and specific inhibitors of cytochrome P-450, the CO inhibition being partially reversed by light. It is concluded that in Zea mays microsomes, obtusifoliol is demethylated at C-14 by a cytochrome P-450 containing monooxygenase system.
mesh_terms: D002384:Catalysis; D002775:Cholestadienols / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System; D003640:Dealkylation; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D008861:Microsomes / Q000201:enzymology; D010105:Oxygenases / Q000378:metabolism*; D010944:Plants / Q000201:enzymology*
chemical_list: D002775:Cholestadienols; C008693:obtusifoliol; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases