Mitochondrial recycling of ascorbic acid as a mechanism for regenerating cellular ascorbate
Mitochondrial recycling of ascorbic acid as a mechanism for regenerating cellular ascorbate
复制标题
DOI：
10.1002/biof.5520300105
复制
发表时间：
2007-01-01
期刊：
影响因子：
6
通讯作者：
Cobb, Charles E.
中科院分区：
文献类型：
--
作者：
May, James M.;Li, Liying;Cobb, Charles E.
线粒体是大多数细胞中潜在破坏性活性氧的主要来源。由于抗坏血酸或维生素C可以保护细胞免受氧化应激，我们研究了从豚鼠骨骼肌中制备的线粒体从其氧化形式中回收维生素的能力。虽然新鲜制备的线粒体中的抗坏血酸浓度仅为约0.2 mM，但当提供6 mM琥珀酸盐和1 mM脱氢抗坏血酸盐（维生素的双电子氧化形式）时，线粒体能够产生并维持高达4 mM的浓度，同时将大部分抗坏血酸盐释放到孵育培养基中。线粒体还原脱氢抗坏血酸强烈抑制1，3-二（氯乙基）-1-亚硝基脲和氧化苯胂。尽管现有的证据表明，线粒体抗坏血酸保护细胞器免受氧化损伤，抗坏血酸未能保存线粒体α-生育酚在含氧缓冲液中长时间孵育。尽管如此，线粒体的抗坏血酸从其氧化形式，抗坏血酸依赖的铁氰化物还原测定的回收能力，是几倍大于总的稳态抗坏血酸浓度。这一点，以及发现超过一半的抗坏血酸从脱氢抗坏血酸再循环逃脱的线粒体，表明线粒体再循环的抗坏血酸可能是一个重要的机制再生细胞内的抗坏血酸。
Mitochondria are the major source of potentially damaging reactive oxygen species in most cells. Since ascorbic acid, or vitamin C, can protect against cellular oxidant stress, we studied the ability of mitochondria prepared from guinea pig skeletal muscle to recycle the vitamin from its oxidized forms. Although ascorbate concentrations in freshly prepared mitochondria were only about 0.2 mM, when provided with 6 mM succinate and 1 mM dehydroascorbate (the two-electron-oxidized form of the vitamin), mitochondria were able to generate and maintain concentrations as high as 4 mM, while releasing most of the ascorbate into the incubation medium. Mitochondrial reduction of dehydroascorbate was strongly inhibited by 1,3-bis(chloroethyl)-1-nitrosourea and by phenylarsine oxide. Despite existing evidence that mitochondrial ascorbate protects the organelle from oxidant damage, ascorbate failed to preserve mitochondrial alpha-tocopherol during prolonged incubation in oxygenated buffer. Nonetheless, the capacity for mitochondria to recycle ascorbate from its oxidized forms, measured as ascorbate-dependent ferricyanide reduction, was several-fold greater than total steady-state ascorbate concentrations. This, and the finding that more than half of the ascorbate recycled from dehydroascorbate escaped the mitochondrion, suggests that mitochondrial recycling of ascorbate might be an important mechanism for regenerating intracellular ascorbate.