DIRECT EVIDENCE FOR THE PRESENCE OF A ROTENONE-RESISTANT NADH DEHYDROGENASE ON THE INNER SURFACE OF THE INNER MEMBRANE OF PLANT-MITOCHONDRIA
DIRECT EVIDENCE FOR THE PRESENCE OF A ROTENONE-RESISTANT NADH DEHYDROGENASE ON THE INNER SURFACE OF THE INNER MEMBRANE OF PLANT-MITOCHONDRIA
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DOI：
10.1111/j.1399-3054.1982.tb00258.x
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发表时间：
1982-01-01
影响因子：
6.4
通讯作者：
PALMER, JM
中科院分区：
文献类型：
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作者：
MOLLER, IM;PALMER, JM
以耶路撒冷（Helianthus tuberosus L.）通过超声处理和差速离心分离线粒体。SMP为约0.00000。50%由内而外，通过还原细胞色素c进入细胞色素c氧化酶来测量。SMP的解偶联NADH氧化（1 mM NADH）为120 nmol O2 min-1 mg-1，在EGTA存在下，其降低至98 nmol O2 min-1（mg线粒体蛋白）-1。完整线粒体对NADH的氧化被EGTA完全抑制（从182-14 nmol O2 min-1 mg-1）。SMP的EGTA抗性NADH氧化归因于内膜内侧的NADH脱氢酶，并暴露于由内而外的SMP中的介质。在EGTA 2存在下，SMP中存在NADH脱氢酶活性。其中一个对NADH的表观Km为7 μ M，Vmax为80 nmol NADH min-1 mg-1，并且是鱼藤酮敏感的。这种脱氢酶相当于哺乳动物复合物I NADH脱氢酶。另一种脱氢酶是鱼藤酮抗性的，其Km为80 μ M，Vmax为131 nmol NADH min-1 mg-1;它可能负责通常在植物线粒体中观察到的有机酸的鱼藤酮抗性氧化。吡啶核苷酸的氧化还原电位对2种内肽酶的相对速率只有很小的影响。通过这些脱氢酶的电子流似乎主要受线粒体基质中NADH浓度的调节。
Submitochondrial particles (SMP) were produced from Jerusalem artichoke (Helianthus tuberosus L.) mitochondria by sonication and differential centrifugation. The SMP were .apprx. 50% inside-out as measured by the access of reduced cytochrome c to cytochrome c oxidase. Uncoupled NADH oxidation (1 mM NADH) by the SMP was 120 nmol O2 min-1 mg-1, which was reduced to 98 nmol O2 min-1 (mg mitochondrial protein)-1 in the presence of EGTA. The oxidation of NADH by intact mitochondria was completely inhibited by EGTA (from 182-14 nmol O2 min-1 mg-1). The EGTA-resistant NADH oxidation by the SMP is ascribed to the NADH dehydrogenase(s) on the inside of the inner membrane and exposed to the medium in the inside-out SMP. In the presence of EGTA 2 NADH dehydrogenase activities were present in the SMP. One had an apparent Km of 7 .mu.M for NADH, a Vmax of 80 nmol of NADH min-1 mg-1, and was rotenone-sensitive. This dehydrogenase is equivalent to the mammalian complex I NADH dehydrogenase. The other dehydrogenase, which was rotenone-resistant, had a Km of 80 .mu.M and a Vmax of 131 nmol NADH min-1 mg-1; it is probably responsible for the rotenone-resistant oxidation of organic acids often observed in plant mitochondria. The redox poise of the pyridine nucleotides had only a small effect on the relative rates of the 2 internal dehydrogenases. Electron flow through these dehydrogenases appears to be regulated mainly by the concentration of NADH in the matrix of the mitochondria.