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Some evidence of the enzymatic conversion of bovine suppressor phosphoseryl‐tRNA to selenocysteyl‐tRNA
Author(s) -
Mizutani Takaharu
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80707-0
Subject(s) - selenocysteine , transfer rna , biochemistry , enzyme , chemistry , amino acid , glutathione , biology , cysteine , gene , rna
In order to clarify the mechanisms of selenocysteine incorporation into glutathione peroxidase, some evidence to show the in vitro conversion of phosphoseryl‐tRNA to selenocysteyl‐tRNA is reported. [ 3 H]Phosphoseryl‐tRNA was incubated in a reaction mixture composed of SeO 2 , glutathione and NADPH in the presence of selenium‐transferase partially purified. Analyses of amino acids on the product tRNA showed that a part (4%) of [ 3 H]phosphoseryl‐tRNA was changed to [ 3 H]selenocysteyl‐tRNA. The conversion from seryl‐tRNA su or major seryl‐tRNA IGA was not found. Selenium‐transferase was essential for the conversion. [ 3 H]Selenocysteine, liberated from the tRNA, was modified with iodoacetic acid. The product was confirmed to be carboxymethyl‐selenocysteine by two‐dimensional TLC. Selenocysteyl‐tRNA su should be used to synthesize glutathione peroxidase by co‐translational mechanisms.