title: Modulation of 3 alpha-hydroxysteroid dehydrogenase activity by the redox state of glutathione.
abstract: 3 alpha-Hydroxysteroid dehydrogenase (EC 1.1.1.50), purified to homogeneity from rat liver, was strongly inactivated by incubation with a disulfide such as GSSG, L-cystine or L-cystamine, as well as an SH-reagent such as DTNB (5,5'-dithiobis(2-nitrobenzoic acid)), NEM (N-ethylmaleimide) or iodoacetic acid. The inactivation advanced with incubation time. Coenzyme (NADP+) completely protected the enzyme from this inactivation by disulfides, but neither of the substrates (androsterone and benzenedihydrodiol) did. The activity of inactivated enzyme was restored by treatment with thiols such as DTT (dithiothreitol) or GSH. In the GSH/GSSG redox buffer, the enzyme existed in an equilibrium between active (reduced) and inactive (oxidized) forms.
authors.affiliation: Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Osaka University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Terada
authors.forename: H
authors.initials: H
authors.lastname: Nanjo
authors.forename: K
authors.initials: K
authors.lastname: Shinagawa
authors.forename: T
authors.initials: T
authors.lastname: Umemura
authors.forename: T
authors.initials: T
authors.lastname: Nishinaka
authors.forename: T
authors.initials: T
authors.lastname: Mizoguchi
authors.forename: T
authors.initials: T
authors.lastname: Nishihara
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000037:antagonists & inhibitors*; D000818:Animals; D002021:Buffers; D004220:Disulfides / Q000494:pharmacology; D005978:Glutathione / Q000737:chemistry / Q000502:physiology*; D008099:Liver / Q000201:enzymology; D009249:NADP / Q000494:pharmacology; D010084:Oxidation-Reduction; D051381:Rats; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000494:pharmacology
chemical_list: D002021:Buffers; D004220:Disulfides; D013438:Sulfhydryl Compounds; D009249:NADP; D015096:3-Hydroxysteroid Dehydrogenases; D005978:Glutathione