title: Microsomal alcohol oxygenase: purification and characterization of a cytochrome P450 responsible for oxidation of 7-hydroxy-delta 8-tetrahydrocannabinol to 7-oxo-delta 8-tetrahydrocannabinol in guinea pig liver.
abstract: Guinea pig hepatic enzyme, microsomal alcohol oxygenase, was able to oxidize both 7 alpha- and 7 beta-hydroxy-delta 8-tetrahydrocannabinol (7 alpha- and 7 beta-hydroxy-delta 8-THC) to 7-oxo-delta 8-THC. A cytochrome P450, named P450GPF-B, which mediates this oxidative metabolism was purified from hepatic microsomes of untreated female guinea pigs. The purified enzyme showed a single protein band of molecular mass 50,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The NH2-terminal amino acid sequence of P450GPF-B is highly homologous with those of several cytochrome P450s belonging to the CYP3A subfamily. 18O derived from atmospheric oxygen was incorporated into 31 and 6%, respectively, of 7-oxo-delta 8-THC formed from 7 alpha- and 7 beta-hydroxy-delta 8-THC when the substrates were incubated with P450GPF-B under 18O2. The antibody against P450GPF-B significantly suppressed the oxidative activities of 7 alpha- and 7 beta-hydroxy-delta 8-THC to 7-oxo-delta 8-THC in hepatic microsomes of guinea pig. These results indicate that P450GPF-B is a major enzyme responsible for the hepatic microsomal alcohol oxygenase activities in the guinea pig.
authors.affiliation: Department of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Matsunaga
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
authors.forename: A
authors.initials: A
authors.lastname: Komura
authors.forename: K
authors.initials: K
authors.lastname: Watanabe
authors.forename: I
authors.initials: I
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Yoshimura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D002852:Chromatography, Ion Exchange; D006224:Cricetinae; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D007700:Kinetics; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D010089:Oxidoreductases, N-Demethylating / Q000737:chemistry; D010105:Oxygenases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D051381:Rats; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012727:Sex Characteristics; D013379:Substrate Specificity
chemical_list: C109363:7-hydroxy-delta(8)-tetrahydrocannabinol; C109364:7-oxo-delta(8)-tetrahydrocannabinol; D010446:Peptide Fragments; D013759:Dronabinol; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; C109362:cytochrome P450GPF-B; D001189:Aryl Hydrocarbon Hydroxylases; D051544:Cytochrome P-450 CYP3A; D010089:Oxidoreductases, N-Demethylating