External alternative NADH dehydrogenase of Saccharomyces cerevisiae:: A potential source of superoxide
External alternative NADH dehydrogenase of Saccharomyces cerevisiae:: A potential source of superoxide
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DOI：
10.1016/s0891-5849(02)01328-x
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发表时间：
2003-02-15
影响因子：
7.4
通讯作者：
Beattie, DS
中科院分区：
文献类型：
--
作者：
Fang, J;Beattie, DS
三种鱼藤酮不敏感的NADH脱氢酶存在于酵母酿酒酵母的线粒体中，它们缺乏复合物I。为了阐明这些酶的功能，在酵母线粒体中测定超氧化物的产生。线粒体与琥珀酸、苹果酸或NADH孵育后产生的低水平过氧化氢（0.10 - 0.18 nmol/min/mg）被抗霉素A刺激9倍。Myxothiazol和stigmatellin完全阻断过氧化氢的形成与琥珀酸或苹果酸，表明细胞色素bc，复合物是超氧化物的来源，然而，这些抑制剂仅抑制46%的过氧化氢的形成与NADH作为底物。二苯基碘抑制过氧化氢的形成（以NADH为底物）64%。超氧化物的形成，测定EPR和乙酰化细胞色素c减少线粒体中的抗霉素A刺激，部分抑制粘噻唑和stigmatellin。蛋白酶K消化的线粒体减少95%的NADH脱氢酶活性与类似的抑制超氧化物的产生。温和的去污剂处理的蛋白酶处理的有丝分裂体导致在NADH脱氢酶活性的增加，由于外源性NADH的氧化由内部的NADH脱氢酶，但是，几乎没有增加超氧化物的产生进行了观察。这些结果表明，外源性NADH脱氢酶是S.酿酒酵母线粒体。(C)2003年爱思唯尔科学公司
Three rotenone-insensitive NADH dehydrogenases are present in the mitochondria of yeast Saccharomyces cerevisiae, which lack complex I. To elucidate the functions of these enzymes, superoxide production was determined in yeast mitochondria. The low levels of hydrogen peroxide (0.10 to 0.18 nmol/min/mg) produced in mitochondria incubated with succinate, malate, or NADH were stimulated 9-fold by antimycin A. Myxothiazol and stigmatellin blocked completely hydrogen peroxide formation with succinate or malate, indicating that the cytochrome bc, complex is the source of superoxide; however, these inhibitors only inhibited 46% hydrogen peroxide formation with NADH as substrate. Diphenyliodonium inhibited hydrogen peroxide formation (with NADH as substrate) by 64%. Superoxide formation, determined by EPR and acetylated cytochrome c reduction in mitochondria was stimulated by antimycin A, and partially inhibited by myxothiazol and stigmatellin. Proteinase K digestion of mitoplasts reduced 95% NADH dehydrogenase activity with a similar inhibition of superoxide production. Mild detergent treatment of the proteinase-treated mitoplasts resulted in an increase in NADH dehydrogenase activity due to the oxidation of exogenous NADH by the internal NADH dehydrogenase; however, little increase in superoxide production was observed. These results suggest that the external NADH dehydrogenase is a potential source of superoxide in S. cerevisiae mitochondria. (C) 2003 Elsevier Science Inc.