title: Organic hydroperoxide-induced activation of liver microsomal glutathione S-transferase of rats in vitro.
abstract: The effect of t-butyl hydroperoxide (t-BuOOH), cumene hydroperoxide (CuOOH) or linoleic acid hydroperoxide (linoleic-OOH) on liver microsomal glutathione S-transferase of rats was studied in vitro. When microsomes were incubated with either 100 microM t-BuOOH or 25 microM CuOOH, glutathione S-transferase activity was increased 1.5-fold; activity was further increased to 2.2-fold in the presence of small amounts of glutathione. The same amounts of dithiothreitol or cysteine did not enhance the t-BuOOH or CuOOH-induced increase in transferase activity. The transferase activity was also increased 1.4-fold by 10 microM linoleic-OOH plus 1 microM glutathione. The increase in microsomal glutathione S-transferase activity after treatment of microsomes with t-BuOOH in the presence of glutathione was completely reversed by addition of dithiothreitol, whereas the activation of the transferase caused by t-BuOOH in the absence of glutathione was not reversed. Although microsomal glutathione S-transferase also possesses glutathione peroxidase activity, only transferase activity was increased by t-BuOOH in either the presence or absence of glutathione. These data indicate that microsomal glutathione S-transferase is activated by organic hydroperoxides in either the absence or presence of small amounts of glutathione, suggesting an activation of the transferase by thiol oxidation of the cysteine residue.
authors.affiliation: Laboratory of Physiology and Pharmacology, School of Health Sciences, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Aniya
authors.forename: A
authors.initials: A
authors.lastname: Daido
mesh_terms: D000818:Animals; D001555:Benzene Derivatives / Q000494:pharmacology; D003545:Cysteine / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005982:Glutathione Transferase / Q000378:metabolism*; D066298:In Vitro Techniques; D008054:Lipid Peroxides / Q000494:pharmacology; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D016877:Oxidants / Q000494:pharmacology; D010545:Peroxides / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D020122:tert-Butylhydroperoxide
chemical_list: D001555:Benzene Derivatives; D008054:Lipid Peroxides; D016877:Oxidants; D010545:Peroxides; D013438:Sulfhydryl Compounds; D020122:tert-Butylhydroperoxide; D005982:Glutathione Transferase; D003545:Cysteine; C007164:cumene hydroperoxide; D004229:Dithiothreitol