title: In vitro synthesis of glutathione peroxidase from selenite. Translational incorporation of selenocysteine.
abstract: The synthesis of glutathione peroxidase from [75Se]selenite was studied in slices and cell-free extracts from rat liver. The incorporation of [75Se]selenocysteine at the active site was detected by carboxymethylation and hydrolysis of partially purified glutathione peroxidase (glutathione:hydrogen peroxide oxidoreductase, EC 1.11.1.9) in the presence of [3H]selenocysteine and subsequent amino acid analysis. The synthesis of glutathione peroxidase in slices was inhibited by cycloheximide or puromycin and 75Se was incorporated from [75Se]selenite into free selenocysteine and selenocysteyl tRNA. Increasing concentrations of selenocystine caused a progressive dilution of the 75Se and a corresponding decrease in glutathione peroxidase labeling. In cell-free systems, [75Se]selenocysteyl tRNA was the best substrate for glutathione peroxidase synthesis. These results indicate the existence in rat liver of the de novo synthesis of free selenocysteine and a translational pathway of selenocysteine incorporation into glutathione peroxidase.
mesh_terms: D000818:Animals; D002474:Cell-Free System; D003545:Cysteine / Q000031:analogs & derivatives* / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000235:genetics*; D066298:In Vitro Techniques; D008099:Liver / Q000201:enzymology*; D008297:Male; D010544:Peroxidases / Q000235:genetics*; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D020887:Selenious Acid; D012643:Selenium / Q000378:metabolism*; D017279:Selenocysteine
chemical_list: D017279:Selenocysteine; D012343:RNA, Transfer; D010544:Peroxidases; D005979:Glutathione Peroxidase; D020887:Selenious Acid; D012643:Selenium; D003545:Cysteine