title: Regulation of rat liver microsomal glutathione S-transferase activity by thiol/disulfide exchange.
abstract: The regulation of purified glutathione S-transferase from rat liver microsomes was studied by examining the effects of various sulfhydryl reagents on enzyme activity with 1-chloro-2,4-dinitrobenzene as the substrate. Diamide (4 mM), cystamine (5 mM), and N-ethylmaleimide (1 mM) increased the microsomal glutathione S-transferase activity by 3-, 2-, and 10-fold, respectively, in absence of glutathione; glutathione disulfide had no effect. In presence of glutathione, microsomal glutathione S-transferase activity was increased 10-fold by diamide (0.5 mM), but the activation of the transferase by N-ethylmaleimide or cystamine was only slightly affected by presence of glutathione. The activation of microsomal glutathione S-transferase by diamide or cystamine was reversed by the addition of dithiothreitol. Glutathione disulfide increased microsomal glutathione S-transferase activity only when membrane-bound enzyme was used. These results indicate that microsomal glutathione S-transferase activity may be regulated by reversible thiol/disulfide exchange and that mixed disulfide formation of the microsomal glutathione S-transferase with glutathione disulfide may be catalyzed enzymatically in vivo.
authors.affiliation: Laboratory of Physiology and Pharmacology, School of Health Sciences, University of the Ryukyus, Okinawa, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Aniya
authors.forename: M W
authors.initials: MW
authors.lastname: Anders
mesh_terms: D000818:Animals; D001391:Azo Compounds / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology; D003958:Diamide / Q000494:pharmacology*; D004220:Disulfides / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D019803:Glutathione Disulfide; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D001391:Azo Compounds; D004220:Disulfides; D013438:Sulfhydryl Compounds; D003958:Diamide; D005982:Glutathione Transferase; D005978:Glutathione; D004229:Dithiothreitol; D019803:Glutathione Disulfide