| First Author | Mozier NM | Year | 1988 |
| Journal | J Biol Chem | Volume | 263 |
| Issue | 10 | Pages | 4527-31 |
| PubMed ID | 3350800 | Mgi Jnum | J:26180 |
| Mgi Id | MGI:73845 | Doi | 10.1016/s0021-9258(18)68814-3 |
| Citation | Mozier NM, et al. (1988) S-adenosyl-L-methionine:thioether S-methyltransferase, a new enzyme in sulfur and selenium metabolism. J Biol Chem 263(10):4527-31 |
| abstractText | The final urinary excretion product of selenium detoxification is trimethylselenonium ion. An assay has been developed for the enzyme, S-adenosylmethionine:thioether S-methyltransferase, responsible for this final methylation reaction. This assay employed high pressure liquid chromatography separation and quantitation of the trimethylselenonium ion produced by thioether methyltransferase acting on S-adenosylmethionine and dimethyl selenide. The enzyme was shown to reside primarily in the cytosol of mouse lung (30 pmol/mg protein/min) and liver (7 pmol/mg protein/min). Purification from mouse lung to a preparation that exhibited a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was achieved by DEAE, gel filtration, and chromatofocusing chromatographies. Thioether methyltransferase is monomeric with a molecular weight of 28,000 and has a pI of 5.3. The pH optimum was 6.3, and Km values for dimethyl selenide and S-adenosylmethionine were 0.4 and 1.0 microM, respectively. The enzyme was inhibited 50% by 25 microM sinefungin, an analog of S-adenosylmethionine, or 40 microM S-adenosylhomocysteine, the reaction product. Pure thioether methyltransferase methylated selenium in dimethyl selenide, tellurium in dimethyl telluride, and S in dimethyl sulfide and many other thioethers. These data suggest a general role for this novel enzyme in the synthesis of onium compounds with increased aqueous solubility helpful in their excretion. |
