Generation of superoxide-radical by the NADH:ubiquinone oxidoreductase of heart mitochondria.
Generation of superoxide-radical by the NADH:ubiquinone oxidoreductase of heart mitochondria.
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心脏线粒体的 NADH：泛醌氧化还原酶产生超氧化物自由基。
DOI：
10.1007/s10541-005-0090-7
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Grivennikova,VG
中科院分区：
文献类型：
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作者：
Vinogradov,AD;Grivennikova,VG
除了主要的NADH-、琥珀酸-和其他底物氧化酶反应导致氧的四电子还原为水之外，线粒体呼吸链催化氧的单电子还原为超氧自由基，随后形成过氧化氢。本文定量研究了在紧偶联的牛心亚线粒体颗粒中复合物I产生超氧化物的能力，琥珀酸控制呼吸过程中超氧化物的形成速率与氧浓度呈线性关系，在饱和氧（0.25 mM）时，超氧化物的形成约占总氧化酶活性的0.4%。琥珀酸氧化过程中单电子氧还原的主要部分（约80%）通过复合物I进行，其依赖性还原（反向电子转移）为代价。在饱和的NADH的形成率是远远小于琥珀酸作为底物。与NADH氧化酶相反，超氧化物产生的速率-底物浓度依赖性在低浓度（约50 µ M）的NADH下显示出最大值。NAD+和NADH抑制琥珀酸支持的超氧化物的产生。复合物I的失活导致其NADH-泛醌还原酶活性几乎完全丧失，并导致NADH依赖性超氧化物生成增加。提出了一个模型，根据该模型，复合物I具有两个氧化还原活性的核苷酸结合位点，一个位点（F）作为NADH氧化的入口，另一个位点（R）作为琥珀酸盐支持的NAD+还原或超氧化物生成或NADH-铁氰化物还原酶反应的出口。
Besides major NADH-, succinate-, and other substrate oxidase reactions resulting in four-electron reduction of oxygen to water, the mitochondrial respiratory chain catalyzes one-electron reduction of oxygen to superoxide radicalfollowed by formation of hydrogen peroxide. In this paper the superoxide generation by Complex I in tightly coupled bovine heart submitochondrial particles is quantitatively characterized.The rate of superoxide formation during-controlled respiration with succinate depends linearly on oxygen concentration and contributes approximately 0.4% of the overall oxidase activity at saturating (0.25 mM) oxygen. The major part of one-electron oxygen reduction during succinate oxidation (∼80%) proceeds via Complex I at the expense of its-dependent reduction (reverse electron transfer). At saturating NADH the rate offormation is substantially smaller than that with succinate as the substrate. In contrast to NADH oxidase,the rate-substrate concentration dependence for the superoxide production shows a maximum at low (∼50 µM)concentrations of NADH. NAD+and NADH inhibit the succinate-supported superoxide generation. Deactivation of Complex I results in almost complete loss of its NADH-ubiquinone reductase activity and in increase in NADH-dependent superoxide generation. A model is proposed according to which complex I has two redox active nucleotide binding sites.One site (F) serves as an entry for the NADH oxidation and the other one (R) serves as an exit during either the succinate-supported NAD+reduction or superoxide generation or NADH-ferricyanide reductase reaction.