title: Testosterone 1 beta-hydroxylation by human cytochrome P450 3A4.
abstract: Human cytochrome P450 3A4 forms a series of minor testosterone hydroxylation products in addition to 6 beta-hydroxytestosterone, the major product. One of these, formed at the next highest rate after the 6 beta- and 2 beta-hydroxy products, was identified as 1 beta-hydroxytestosterone. This product was characterized from a mixture of testosterone oxidation products using an HPLC-solid phase extraction-cryoprobe NMR/time-of-flight mass spectrometry system, with an estimated total of approximately 6 microg of this product. Mass spectrometry established the formula as C(19)H(29)O(3) (MH(+) 305.2080). The 1-position of the added hydroxyl group was established by correlated spectroscopy and heteronuclear spin quantum correlation experiments, and the beta-stereochemistry of the added hydroxyl group was assigned with a nuclear Overhauser correlated spectroscopy experiment (1 alpha-H). Of several human P450s examined, only P450 3A4 formed this product. The product was also formed in human liver microsomes.
authors.affiliation: Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.
authors.forename: Joel A
authors.initials: JA
authors.lastname: Krauser
authors.forename: Markus
authors.initials: M
authors.lastname: Voehler
authors.forename: Li-Hong
authors.initials: LH
authors.lastname: Tseng
authors.forename: Alexandre B
authors.initials: AB
authors.lastname: Schefer
authors.forename: Markus
authors.initials: M
authors.lastname: Godejohann
authors.forename: F Peter
authors.initials: FP
authors.lastname: Guengerich
mesh_terms: D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D006801:Humans; D006900:Hydroxylation; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D013739:Testosterone / Q000378:metabolism*
chemical_list: D009243:NAD; D013739:Testosterone; D009249:NADP; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A