title: Inactivation of human placenta glutathione S-transferase by SH/SS exchange reaction with biological disulfides.
abstract: The oxidized glutathione inhibited the activity of glutathione S-transferase purified from human placenta just through competitive inhibition. On the other hand, cystine and cystamine inactivated the activity by pseudo first-order in low concentrations, accompanying the stoichiometric incorporation of the radioactivity of [14C]-cystine to the enzyme protein until a half mole per one subunit. This and the protective effect of glutathione analogues suggested that the SH/SS exchange reaction occurred between the disulfide and the SH group near the glutathione binding site of the enzyme to form a mixed disulfide.
authors.affiliation: Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences Osaka University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nishihara
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: Oshida
authors.forename: T
authors.initials: T
authors.lastname: Mizoguchi
authors.forename: T
authors.initials: T
authors.lastname: Terada
mesh_terms: D003553:Cystine / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism*; D019803:Glutathione Disulfide; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors*; D006801:Humans; D007700:Kinetics; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D004220:Disulfides; D013438:Sulfhydryl Compounds; D003553:Cystine; D005982:Glutathione Transferase; D005978:Glutathione; D019803:Glutathione Disulfide