9
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: not found
      • Article: not found

      Selenoprotein P in Human Plasma as an Extracellular Phospholipid Hydroperoxide Glutathione Peroxidase : ISOLATION AND ENZYMATIC CHARACTERIZATION OF HUMAN SELENOPROTEIN P

      Read this article at

      ScienceOpenPublisher
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Related collections

          Most cited references33

          • Record: found
          • Abstract: found
          • Article: not found

          Selenocysteine.

          Selenocysteine is recognized as the 21st amino acid in ribosome-mediated protein synthesis and its specific incorporation is directed by the UGA codon. Unique tRNAs that have complementary UCA anticodons are aminoacylated with serine, the seryl-tRNA is converted to selenocysteyl-tRNA and the latter binds specifically to a special elongation factor and is delivered to the ribosome. Recognition elements within the mRNAs are essential for translation of UGA as selenocysteine. A reactive oxygen-labile compound, selenophosphate, is the selenium donor required for synthesis of selenocysteyl-tRNA. Selenophosphate synthetase, which forms selenophosphate from selenide and ATP, is found in various prokaryotes, eukaryotes, and archaebacteria. The distribution and properties of selenocysteine-containing enzymes and proteins that have been discovered to date are discussed. Artificial selenoenzymes such as selenosubtilisin have been produced by chemical modification. Genetic engineering techniques also have been used to replace cysteine residues in proteins with selenocysteine. The mechanistic roles of selenocysteine residues in the glutathione peroxidase family of enzymes, the 5' deiodinases, formate dehydrogenases, glycine reductase, and a few hydrogenases are discussed. In some cases a marked decrease in catalytic activity of an enzyme is observed when a selenocysteine residue is replaced with cysteine. This substitution caused complete loss of glycine reductase selenoprotein A activity.
            Bookmark
            • Record: found
            • Abstract: not found
            • Article: not found

            The selenoenzyme phospholipid hydroperoxide glutathione peroxidase

              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Type I iodothyronine deiodinase is a selenocysteine-containing enzyme.

              Although thyroxine (3,5,3',5'-tetraiodothyronine, T4) is the principal secretory product of the vertebrate thyroid, its essential metabolic and developmental effects are all mediated by 3,5,3'-triiodothyronine (T3), which is produced from the prohormone by 5'-deiodination. The type-I iodothyronine deiodinase, a thiol-requiring propylthiouracil-sensitive oxidoreductase, is found mainly in liver and kidney and provides most of the circulating T3(1) but so far this enzyme has not been purified. Using expression cloning in the Xenopus oocyte, we have isolated a 2.1-kilobase complementary DNA for this deiodinase from a rat liver cDNA library. The kinetic properties of the protein expressed in transient assay systems, the tissue distribution of the messenger RNA, and its changes with thyroid status, all confirm its identity. We find that the mRNA for this enzyme contains a UGA codon for selenocysteine which is necessary for maximal enzyme activity. This explains why conversion of T4 to T3 is impaired in experimental selenium deficiency and identifies an essential role for this trace element in thyroid hormone action.
                Bookmark

                Author and article information

                Journal
                Journal of Biological Chemistry
                J. Biol. Chem.
                American Society for Biochemistry & Molecular Biology (ASBMB)
                0021-9258
                1083-351X
                January 29 1999
                January 29 1999
                January 29 1999
                : 274
                : 5
                : 2866-2871
                Article
                10.1074/jbc.274.5.2866
                697ec005-d588-48e9-83a3-4ace14f2d087
                © 1999
                History

                Comments

                Comment on this article