Schnurr K, Belkner J, Ursini F, Schewe T, Kühn H
Institute of Biochemistry, University Clinics Charité, Humboldt University of Berlin, D-10115 Berlin, Germany.
J Biol Chem. 1996 Mar 1;271(9):4653-8. doi: 10.1074/jbc.271.9.4653.
Mammalian 15-lipoxygenases have been suggested to be involved in cell differentiation and atherogenesis because of their capability of oxygenating polyenoic fatty acids esterified to biomembranes and lipoproteins. We investigated the interaction of the lipid-peroxidizing 15-lipoxygenase and the hydroperoxy lipid-reducing phospholipid hydroperoxide glutathione peroxidase during their reaction with biomembranes and lipoproteins and obtained the following results. 1) Lipoxygenase treatment of submitochondrial membranes led to the formation of hydroperoxyphosphatidylethanolamine and hydroperoxyphosphatidylcholine as indicated by high performance liquid chromatography with chemiluminescence detection. In 15-lipoxygenase-treated low density lipoprotein cholesteryl hydroperoxylinoleate was the major oxygenation product. 2) Phospholipid hydroperoxide glutathione peroxidase was capable of reducing the hydroperoxy lipids formed by the 15-lipoxygenase to their corresponding alcohols. 3) Preincubation of low density lipoprotein and submitochondrial membranes with the phospholipid hydroperoxide glutathione peroxidase completely prevented the lipoxygenase reaction. However, addition of exogenous hydroperoxy lipids restored the oxygenase activity. 4) Short-term incubations of the complex substrates with the 15-lipoxygenase led to a specific pattern of oxidation products which was rendered more unspecific at long-term incubation or at high substrate concentrations. If the phosholipid hydroperoxide glutathione peroxidase was present during the reaction, the specific product pattern was preserved. These data indicate that the phospholipid hydroperoxide glutathione peroxidase is capable of reducing hydroperoxy ester lipids formed by a 15-lipoxygenase, and that it may down-regulate the 15-lipoxygenase pathways in mammalian cells. The specificity of 15-lipoxygenase-derived hydroperoxy lipids depends on their immediate reduction to the corresponding alcohols preventing postcatalytic isomerization.
哺乳动物15-脂氧合酶因其能够氧化生物膜和脂蛋白中酯化的多烯脂肪酸，被认为参与细胞分化和动脉粥样硬化的形成。我们研究了脂质过氧化的15-脂氧合酶与还原氢过氧脂质的磷脂氢过氧化物谷胱甘肽过氧化物酶在与生物膜和脂蛋白反应过程中的相互作用，得到了以下结果。1）用脂氧合酶处理亚线粒体膜后，通过高效液相色谱-化学发光检测表明，形成了氢过氧磷脂酰乙醇胺和氢过氧磷脂酰胆碱。在经15-脂氧合酶处理的低密度脂蛋白中，胆固醇氢过氧亚油酸酯是主要的氧化产物。2）磷脂氢过氧化物谷胱甘肽过氧化物酶能够将15-脂氧合酶形成的氢过氧脂质还原为相应的醇。3）将低密度脂蛋白和亚线粒体膜与磷脂氢过氧化物谷胱甘肽过氧化物酶预孵育，可完全阻止脂氧合酶反应。然而，添加外源性氢过氧脂质可恢复加氧酶活性。4）将复合底物与15-脂氧合酶短期孵育会导致特定的氧化产物模式，而在长期孵育或高底物浓度下这种模式会变得更不具有特异性。如果在反应过程中存在磷脂氢过氧化物谷胱甘肽过氧化物酶，则特定的产物模式会得以保留。这些数据表明，磷脂氢过氧化物谷胱甘肽过氧化物酶能够还原由15-脂氧合酶形成的氢过氧酯脂质，并且它可能下调哺乳动物细胞中的15-脂氧合酶途径。15-脂氧合酶衍生的氢过氧脂质的特异性取决于它们立即还原为相应的醇，从而防止催化后异构化。
