Electron transport-linked ubiquinone-dependent recycling of α-tocopherol inhibits autooxidation of mitochondrial membranes
Electron transport-linked ubiquinone-dependent recycling of α-tocopherol inhibits autooxidation of mitochondrial membranes
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DOI：
10.1006/abbi.1997.0606
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发表时间：
1998-04-15
影响因子：
3.9
通讯作者：
Sohal, RS
中科院分区：
文献类型：
--
作者：
Lass, A;Sohal, RS
本研究的目的是通过确定辅酶Q(CoQ)在线粒体膜自氧化过程中是直接清除过氧基和烷氧基还是间接再生铜生育酚来阐明辅酶Q(CoQ)和α-生育酚在线粒体膜中的抗氧化作用。比较了α-生育酚和辅酶Q在牛和大鼠心脏线粒体自氧化过程中的相互作用，它们的含量相差15倍。牛和大鼠心脏线粒体膜的自氧化均可导致硫代巴比妥酸反应物质和蛋白质羰基的形成，但大鼠和牛心线粒体膜的自氧化性差异相对较小。在自氧化过程中，补充琥珀酸可使辅酶Q降低为泛喹酚，而铜生育酚浓度保持不变。相反，在没有琥珀酸的情况下，辅酶Q以氧化形式(辅酶Q)存在，线粒体膜上的细胞生育酚被耗尽，辅酶Q浓度随时间保持不变，无论是否有琥珀酸。在没有琥珀酸的情况下，添加不同数量的α-生育酚的牛SMPS的自氧化与α-生育酚的量成反比，而在琥珀酸存在的情况下，辅酶Q的自氧化大大减少。本研究结果表明，在线粒体自氧化过程中，α-生育酚I作为直接的自由基清除剂，而泛喹酚则再生铜生育酚。(C)1998年学术出版社。
The objective of this study was to elucidate the antioxidative roles of coenzyme Q (CoQ) and alpha-tocopherol in mitochondrial membranes by determining whether CoQ directly scavenges peroxyl-and alkoxyl-radicals or indirectly regenerates cu-tocopherol during autooxidation of mitochondrial membranes. A comparison of the interaction between alpha-tocopherol and CoQ during autooxidation was made between bovine and rat heart mitochondria, which differ similar to 15-fold in their alpha-tocopherol content. Autooxidation of both bovine and rat heart mitochondria resulted in the formation of thiobarbituric-acid-reactive substances and protein carbonyls; however, the differences in the autooxidizability of mitochondria between rat and bovine heart mitochondrial membranes were relatively minor. Supplementation of rat heart mitochondria with succinate caused reduction of CoQ to ubiquinol while cu-tocopherol concentration remained unaffected during autooxidation. In contrast, in the absence of succinate, CoQ was present in the oxidized form (ubiquinone) and the mitochondrial membranes were depleted of cy-tocopherol, CoQ concentrations remained unchanged over time irrespective of the presence or absence of succinate, In the absence of succinate, autooxidation of bovine SMPs, supplemented with different amounts of alpha-tocopherol, was inversely related to the amount of alpha-tocopherol, whereas in the presence of succinate autooxidation was greatly reduced. Results of this study indicate that during autooxidation of mitochondria, alpha tocopheroI acts as the direct radical scavenger, whereas ubiquinol regenerates cu-tocopherol. (C) 1998 Academic Press.