title: Thymine hydroperoxide, a substrate for rat Se-dependent glutathione peroxidase and glutathione transferase isoenzymes.
abstract: The thymine hydroperoxide, 5-hydroperoxymethyluracil, is a substrate for Se-dependent glutathione (GSH) peroxidase and the Se-independent GSH peroxidase activity associated with the GSH transferase fraction. These enzymes may contribute to repair mechanisms for damage caused by oxygen radicals. GSH transferases 1-1, 2-2, 3-3, 4-4, 6-6, and 7-7 [(1984) Biochem. Pharmacol. 33, 2539-2540] are shown to differ considerably in their ability to utilize this substrate. For example, high activity is found in GSH transferase 6-6 which is the major isoenzyme in spermatogenic tubules where DNA synthesis is so active and faithful DNA replication so important. The activity of the purified GSH transferase isoenzymes towards 5-hydroperoxymethyluracil is comparable with their activity towards other endogenous substrates related to cellular peroxidation such as linoleate hydroperoxide and 4-hydroxynon-2-enal or biologically important xenobiotic metabolites such as benzo(a)pyrene-7,8-diol-9,10-oxide.
mesh_terms: D000818:Animals; D004260:DNA Repair; D005609:Free Radicals; D005979:Glutathione Peroxidase / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D010100:Oxygen; D051381:Rats; D012643:Selenium / Q000494:pharmacology*; D013379:Substrate Specificity; D013941:Thymine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D005609:Free Radicals; D007527:Isoenzymes; C011851:5-hydroperoxymethyluracil; D005979:Glutathione Peroxidase; D005982:Glutathione Transferase; D012643:Selenium; D013941:Thymine; D010100:Oxygen