Publications

• Non-reactivity of the selenoenzyme glutathione peroxidase with enzymatically hydroperoxidized phospholipids.

  Grossmann A., Wendel A.

  Selenium-containing glutathione peroxidase (EC 1.11.1.9) was purified 6000-fold from bovine red blood cells to apparent homogeneity. Lipoxygenase (EC 1.13.11.12) was enriched 20-fold from soybean acetone powder. Linoleic acid was peroxidized with lipoxygenase and then used as a substrate in the gl ... >> More

  Selenium-containing glutathione peroxidase (EC 1.11.1.9) was purified 6000-fold from bovine red blood cells to apparent homogeneity. Lipoxygenase (EC 1.13.11.12) was enriched 20-fold from soybean acetone powder. Linoleic acid was peroxidized with lipoxygenase and then used as a substrate in the glutathione peroxidase reaction. Analogous experiments were conducted with synthetic 1,2-dilinoleoyl-L-alpha-glycerophosphocholine and with natural bovine heart cardiolipin. The peroxidized phospholipids were reactive with glutathione peroxidase only after enzymatic attack by phospholipase A2 (EC 3.1.1.4). This result implies that the membrane-protective function of glutathione peroxidase includes preceeding phospholipase action and excludes a direct interaction of this enzyme with membrane-bound lipid hydroperoxides. << Less

  Eur J Biochem 135:549-552(1983) [PubMed] [EuropePMC]

• Novel glutaredoxin activity of the yeast prion protein Ure2 reveals a native-like dimer within fibrils.

  Zhang Z.R., Perrett S.

  Ure2 is the protein determinant of the Saccharomyces cerevisiae prion [URE3]. Ure2 has structural similarity to glutathione transferases, protects cells against heavy metal and oxidant toxicity in vivo, and shows glutathione-dependent peroxidase activity in vitro. Here we report that Ure2 (which h ... >> More

  Ure2 is the protein determinant of the Saccharomyces cerevisiae prion [URE3]. Ure2 has structural similarity to glutathione transferases, protects cells against heavy metal and oxidant toxicity in vivo, and shows glutathione-dependent peroxidase activity in vitro. Here we report that Ure2 (which has no cysteine residues) also shows thiol-disulfide oxidoreductase activity similar to that of glutaredoxin enzymes. This demonstrates that disulfide reductase activity can be independent of the classical glutaredoxin CXXC/CXXS motif or indeed an intrinsic catalytic cysteine residue. The kinetics of the glutaredoxin activity of Ure2 showed positive cooperativity for the substrate glutathione in both the soluble native state and in amyloid-like fibrils, indicating native-like dimeric structure within Ure2 fibrils. Characterization of the glutaredoxin activity of Ure2 sheds light on its ability to protect yeast from heavy metal ion and oxidant toxicity and suggests a role in reversible protein glutathionylation signal transduction. Observation of allosteric enzyme behavior within amyloid-like Ure2 fibrils not only provides insight into the molecular structure of the fibrils but also has implications for the mechanism of [URE3] prion formation. << Less

  J. Biol. Chem. 284:14058-14067(2009) [PubMed] [EuropePMC]

• Side-by-side comparison of recombinant human glutathione peroxidases identifies overlapping substrate specificities for soluble hydroperoxides.

  Schwarz M., Loeser A., Cheng Q., Wichmann-Costaganna M., Schaedel P., Werz O., Arner E.S., Kipp A.P.

  Five out of eight human glutathione peroxidases (GPXs) are selenoproteins, representing proteins that contain selenium as part of the amino acid selenocysteine. The GPXs are important for reducing hydroperoxides in a glutathione-consuming manner and thus regulate cellular redox homeostasis. GPX1, ... >> More

  Five out of eight human glutathione peroxidases (GPXs) are selenoproteins, representing proteins that contain selenium as part of the amino acid selenocysteine. The GPXs are important for reducing hydroperoxides in a glutathione-consuming manner and thus regulate cellular redox homeostasis. GPX1, GPX2, and GPX4 represent the three main cytosolic GPXs, but they differ in their expression patterns with GPX1 and GPX4 being expressed ubiquitously, whereas GPX2 is mainly expressed in epithelial cells. GPX1 and GPX2 have been described to reduce soluble hydroperoxides, while GPX4 reduces complex lipid hydroperoxides, thus protecting cells from lipid peroxidation and ferroptosis. But most of these data are derived from cells that are devoid of one of the isoforms and thus, compensation or other cellular effects might affect the conclusions. So far, the use of isolated recombinant human selenoprotein glutathione peroxidases in pure enzyme assays has not been employed to study their substrate specificities side by side. Using recombinant GPX1, GPX2, and GPX4 produced in E. coli we here assessed their GPX activities by a NADPH-consuming glutathione reductase-coupled assay with 17 different peroxides (all at 50 μM) as substrates. GPX4 was clearly the only isoform able to reduce phosphatidylcholine hydroperoxide. In contrast, small soluble hydroperoxides such as H₂O₂, cumene hydroperoxide, and tert-butyl hydroperoxide were reduced by all three isoforms, but with approximately 10-fold higher efficiency for GPX1 in comparison to GPX2 and GPX4. Also, several fatty acid-derived hydroperoxides were reduced by all three isoforms and again GPX1 had the highest activity. Interestingly, the stereoisomerism of the fatty acid-derived hydroperoxides clearly affected the activity of the GPX enzymes. Overall, distinct substrate specificity is obvious for GPX4, but not so when comparing GPX1 and GPX2. Clearly GPX1 was the most potent isoform of the three GPXs in terms of turnover in reduction of soluble and fatty-acid derived hydroperoxides. << Less

  Redox Biol. 59:102593-102593(2023) [PubMed] [EuropePMC]

  This publication is cited by 14 other entries.

• Glutathione peroxidase.

  Mannervik B.

  Methods Enzymol 113:490-495(1985) [PubMed] [EuropePMC]

• Purification and characterization of selenium-glutathione peroxidase from hamster liver.

  Chaudiere J., Tappel A.L.

  Hamster liver glutathione peroxidase was purified to homogeneity in three chromatographic steps and with 30% yield. The purified enzyme had a specific activity of approximately 500 mumol cumene hydroperoxide reduced/min/mg of protein at 37 degrees C, pH 7.6, and 0.25 mM GSH. The enzyme was shown t ... >> More

  Hamster liver glutathione peroxidase was purified to homogeneity in three chromatographic steps and with 30% yield. The purified enzyme had a specific activity of approximately 500 mumol cumene hydroperoxide reduced/min/mg of protein at 37 degrees C, pH 7.6, and 0.25 mM GSH. The enzyme was shown to be a tetramer of indistinguishable subunits, the molecular weight of which was approximately 23,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A single isoelectric point of 5.0 was attributed to the active enzyme. Amino acid analysis determined that selenocysteine, identified as its carboxymethyl derivative, was the only form of selenium. One residue of cysteine was found to be present in each glutathione peroxidase subunit. The presence of tryptophan was colorimetrically determined. Pseudo-first-order kinetics of inactivation of the enzyme by iodoacetate was observed at neutral pH with GSH as the only reducing agent. An optimal pH of 8.0 at 37 degrees C and an activation energy of 3 kcal/mol at pH 7.6 were found. A ter-uni-ping-pong mechanism was shown by the use of an integrated-rate equation. At pH 7.6, the apparent second-order rate constants for reaction of glutathione peroxidase with hydroperoxides were as follows: k1 (t-butyl hydroperoxide), 7.06 X 10(5) mM-1 min-1; k1 (cumene hydroperoxide), 1.04 X 10(6) mM-1 min-1; k1 (p-menthane hydroperoxide), 1.2 X 10(6) mM-1 min-1; k1 (diisopropylbenzene hydroperoxide), 1.7 X 10(6) mM-1 min-1; k1 (linoleic acid hydroperoxide), 2.36 X 10(6) mM-1 min-1; k1 (ethyl hydroperoxide), 2.5 X 10(6) mM-1 min-1; and k1 (hydrogen peroxide), 2.98 X 10(6) mM-1 min-1. It is concluded that for bulky hydroperoxides, the more hydrophobic the substrate, the faster its reduction by glutathione peroxidase. << Less

  Arch Biochem Biophys 226:448-457(1983) [PubMed] [EuropePMC]