title: Irreversible inactivation of glutathione S-transferase-π by a low concentration of naphthoquinones.
abstract: π-Class glutathione S-transferase (GST-π) was very potently inactivated by oxidants such as H2O2, xanthine-xanthine oxidase and naphthoquinones. Thiols and glutathione analogs including dithiothreitol, reduced gluta-thione, cysteine, cysteamine, S-methyl-SG, S-hexyl-SG and S-decyl-SG protected GST-π from the inactivation, but a substrate analog (2,4-dinitrophenol), superoxide dismutase and catalase did not, suggesting that the cysteinyl residue(s) in/nearby the glutathione binding site (G-site) may be oxidatively modified by these oxidants. Many reductants and radical scavengers including butylated hydoxytoluene, α-tocopherol, ascorbate, uric acid, mannitol, tyrosine, tryptophan, histidine, quercitrin and bilirubin had no effect on the inactivation. GST-π pretreated with cystamine was reactivated very efficiently by 50 mM DTT following incubation with 1,2-naphthoquinone, whereas cystamine-untreated GST-π was not reactivated.
authors.affiliation: a Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences , Osaka University , Osaka , Japan.
authors.forename: T
authors.initials: T
authors.lastname: Terada
authors.affiliation: a Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences , Osaka University , Osaka , Japan.
authors.forename: M
authors.initials: M
authors.lastname: Matsumura
authors.affiliation: a Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences , Osaka University , Osaka , Japan.
authors.forename: A
authors.initials: A
authors.lastname: Abe
authors.affiliation: a Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences , Osaka University , Osaka , Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Morita
authors.affiliation: a Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences , Osaka University , Osaka , Japan.
authors.forename: H
authors.initials: H
authors.lastname: Adachi
authors.affiliation: a Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences , Osaka University , Osaka , Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nanjo