Hepatic cytosolic non selenium-dependent glutathione peroxidase activity: its nature and the effect of selenium deficiency.
Recent work had indicated the presence of a non selenium-dependent glutathione peroxidase activity in rat liver in addition to the selenium-dependent activity. The present study was undertaken to learn whether the glutathione S-transferases are reponsible for the non selenium-dependent glutathione peroxidase activity and to study the effect of selenium deficiency on those enzymes. Glutathione S-transferase B was purified by an established method using carboxymethyl cellulose ion exchange chromatography and studied. It exhibited glutathione peroxidase activity toward cumene hydroperoxide and t-butyl hydroperoxide. A limiting Km of 0.55 mM was determined for cumene hydroperoxide. Sulfobromophthalein was found to be a competitive inhibitor with respect to cumene hydroperoxide of the glutathione peroxidase activity of glutathione S-transferase B. Selenium deficiency caused an increase in glutathione S-transferase activity. These results establish that glutathione S-transferase B contributes to the non selenium-dependent glutathione peroxidase activity in rat liver and show that it increases in selenium deficiency when the selenium-dependent glutathione peroxidase is decreased.
D000818:Animals; D003600:Cytosol / Q000201:enzymology; D004790:Enzyme Induction; D005979:Glutathione Peroxidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005982:Glutathione Transferase / Q000302:isolation & purification / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D010544:Peroxidases / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology; D051381:Rats; D012643:Selenium / Q000172:deficiency* / Q000494:pharmacology; D013379:Substrate Specificity
D010544:Peroxidases; D005979:Glutathione Peroxidase; D005982:Glutathione Transferase; D012643:Selenium; D010634:Phenobarbital