Comte J, Gautheron D C
Biochimie. 1978;60(11-12):1289-98.
Evidence is presented about the dual location of NADPH-cytochrome c reductase in mitochondrial outer membranes as well as in microsomes, from pig heart. A high specific activity, was found in both fractions, even after their purification by washing, digitonin treatments, or passages on sucrose gradients. A large fraction of the total activity was associated with both mitochondria and microsomes. Mitochondrial outer membrane differs from microsomes by a low choline phosphotransferase activity and the absence of cytochrome P-450. The properties of mitochondrial and microsomal rotenone-insensitive NADH- and NADPH-cytochrome c reductases were studied. In microsomes, both activities have the same optimum pH (8.5) ; in contrast, in mitochondria they have a different one. The Km-NADPH were always much higher than those for NADH. In mitochondria the Km for NAD(P)H were dependent on cytochrome c concentration. The results show that the rotenone-insensitive NADH- and NADPH-cytochrome c reductases of mitochondria and microsomes have quite different behavior and do not appear to be supported by the same enzyme.
有证据表明，猪心脏线粒体的外膜和微粒体中都存在NADPH-细胞色素c还原酶。即使经过洗涤、洋地黄皂苷处理或蔗糖梯度离心纯化后，在这两种组分中仍发现了高比活性。总活性的很大一部分与线粒体和微粒体都有关联。线粒体的外膜与微粒体不同，其胆碱磷酸转移酶活性较低且不存在细胞色素P-450。对线粒体和微粒体中鱼藤酮不敏感的NADH-和NADPH-细胞色素c还原酶的特性进行了研究。在微粒体中，这两种活性具有相同的最适pH（8.5）；相反，在线粒体中它们的最适pH不同。NADPH的Km值总是远高于NADH的Km值。在线粒体中，NAD(P)H的Km值取决于细胞色素c的浓度。结果表明，线粒体和微粒体中鱼藤酮不敏感的NADH-和NADPH-细胞色素c还原酶具有截然不同的行为，似乎不是由同一种酶支持的。
