Publications

• Selenodiglutathione is a highly efficient oxidant of reduced thioredoxin and a substrate for mammalian thioredoxin reductase.

  Bjornstedt M., Kumar S., Holmgren A.

  Selenium compounds like selenite (SeO3(2-) may form a covalent adduct with glutathione (GSH) in the form of selenodiglutathione (GS-Se-SG), which is assumed to be important in the metabolism of selenium. We have isolated GS-Se-SG and studied its reactions with NADPH and thioredoxin reductase from ... >> More

  Selenium compounds like selenite (SeO3(2-) may form a covalent adduct with glutathione (GSH) in the form of selenodiglutathione (GS-Se-SG), which is assumed to be important in the metabolism of selenium. We have isolated GS-Se-SG and studied its reactions with NADPH and thioredoxin reductase from calf thymus or with thioredoxin reductase and thioredoxin from Escherichia coli. Incubation of 0.1 microM calf thymus thioredoxin reductase or 0.1 microM thioredoxin reductase and 1 microM thioredoxin from E. coli with 5, 10, or 20 microM GS-Se-SG resulted in a fast initial reaction, followed by a large and continued oxidation of NADPH. However, anaerobic incubation of 0.1 microM calf thymus thioredoxin reductase and 20 microM GS-Se-SG resulted only in oxidation of a stoichiometric amount of NADPH; admission of oxygen started continuous NADPH oxidation. Contrary to the mammalian enzyme, GS-Se-SG was not a substrate for thioredoxin reductase from E. coli. The rate of the oxygen-dependent reaction between calf thymus thioredoxin reductase and GS-Se-SG was increased 2-fold in the presence of 4 mM GSH, indicating that HSe-was the reactive intermediate. Glutathione reductase from rat liver reduced GS-Se-SG with a very slow continued oxidation of NADPH, and the presence of the enzyme did not affect the oxygen-dependent nonstoichiometric oxidation of NADPH by GS-Se-SG and thioredoxin reductase. Fluorescence spectroscopy showed GS-Se-SG to be a very efficient oxidant of reduced thioredoxin from E. coli and kinetically superior to insulin disulfides. Thioredoxin-dependent reduction of CDP to dCDP by ribonucleotide reductase was effectively inhibited by GS-Se-SG. << Less

  J Biol Chem 267:8030-8034(1992) [PubMed] [EuropePMC]

• Selenium metabolism in Escherichia coli.

  Turner R.J., Weiner J.H., Taylor D.E.

  Escherichia coli will reduce selenite (SeO3(2-)) and selenate (SeO4(2-)) to elemental selenium Se0. Selenium will also become incorporated into proteins as part of the amino acids selenocysteine or selenomethionine. The reaction of selenite with glutathione produces selenodiglutathione (GS-Se-GS). ... >> More

  Escherichia coli will reduce selenite (SeO3(2-)) and selenate (SeO4(2-)) to elemental selenium Se0. Selenium will also become incorporated into proteins as part of the amino acids selenocysteine or selenomethionine. The reaction of selenite with glutathione produces selenodiglutathione (GS-Se-GS). Selenodiglutathione and its subsequent reduction to glutathioselenol (GS-SeH) are likely the key intermediates in the possible metabolic fates of selenium. This review presents the possible pathways involving selenium in E. coli. Identification of intermediates and potential processes from uptake of the toxic oxyanions through to their detoxification will assist us in understanding the complexities of metalloid oxyanion metabolism in these bacteria. << Less

  Biometals 11:223-227(1998) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.