title: Modulation of glutathione S-transferase activity by a thiol/disulfide exchange reaction and involvement of thioltransferase.
abstract: Low concentrations of cystamine and cystine inactivated human placenta glutathione S-transferase (GST-pi) in cytosolic fraction very effectively, as did the purified enzyme, through the thiol/disulfide exchange reaction. Mixed disulfide formation of GST-pi in cytosol was prevented by thioltransferase existing in cytosol with a low concentration of GSH. This protection of GST-pi activity was more effective with the participation of glutathione reductase. The incorporation of half-[14C]cystine into a GST-pi molecule according to the inactivation was provided by autoradiography. Purified human placenta thioltransferase (1900-fold from cytosol) could release the incorporated half-[14C]cystine from a GST-pi molecule with restoration of enzyme activity. Thioredoxin in placenta cytosol could not protect the GST-pi activity from inactivation at all.
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: Maeda
authors.forename: K
authors.initials: K
authors.lastname: Okamoto
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: D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D003538:Cystamine / Q000494:pharmacology*; D003553:Cystine / Q000378:metabolism* / Q000494:pharmacology*; D003600:Cytosol / Q000201:enzymology; D004220:Disulfides / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D054477:Glutaredoxins; D005978:Glutathione / Q000494:pharmacology*; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007525:Isoelectric Focusing; D009249:NADP / Q000494:pharmacology; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011490:Protein Disulfide Reductase (Glutathione)
chemical_list: D004220:Disulfides; D054477:Glutaredoxins; D003553:Cystine; D009249:NADP; D010088:Oxidoreductases; D011490:Protein Disulfide Reductase (Glutathione); D005982:Glutathione Transferase; D005978:Glutathione; D003538:Cystamine