The inhibition of mitochondrial complex I (NADH:ubiquinone oxidoreductase) by Zn2+
The inhibition of mitochondrial complex I (NADH:ubiquinone oxidoreductase) by Zn2+
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DOI：
10.1074/jbc.m607389200
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发表时间：
2006-11-17
影响因子：
4.8
通讯作者：
Hirst, Judy
中科院分区：
文献类型：
--
作者：
Sharpley, Mark S.;Hirst, Judy
NADH：来自牛心脏线粒体的泛醌氧化还原酶（复合物I）是一种高度复杂的膜结合酶。它是能量转导的中心，是细胞活性氧的重要来源，其功能障碍与神经退行性疾病和肌肉疾病以及衰老有关。在这里，我们描述了Zn 2+对复合物I的影响，以确定复合物I是否有助于介导锌在缺血等状态下的病理作用，并确定Zn 2+如何用于探测复合物I的机制。Zn~（2+）比Mg~（2+）、Ca~（2+）、Ba~（2+）和Mn~（2+）对Cu~（2+）和Cd~（2+）的抑制作用更强。它不抑制NADH氧化或分子内电子转移，因此它可能抑制质子转移到结合醌或质子易位。因此，锌代表了一类新的复合物I抑制剂，明显不同于许多泛醌位点抑制剂。没有证据表明锌抑制复合物I增加了超氧化物的产生。锌与复合物I的结合在机理上是复杂的。在催化过程中，锌缓慢而渐进地结合，但它快速而紧密地结合到酶的静息状态。在添加EDTA后，被抑制的酶的再活化是缓慢的，并且抑制仅部分可逆。复合物I的Zn 2+抑制的IC 50值高（10 - 50 μ M，取决于酶的状态）;因此，复合物I不太可能是锌抑制电子传递链的主要位点。然而，复合物I对Zn 2+浓度变化的缓慢响应可能会增强任何生理后果。
NADH: ubiquinone oxidoreductase (complex I) from bovine heart mitochondria is a highly complicated, membrane-bound enzyme. It is central to energy transduction, an important source of cellular reactive oxygen species, and its dysfunction is implicated in neurodegenerative and muscular diseases and in aging. Here, we describe the effects of Zn2+ on complex I to define whether complex I may contribute to mediating the pathological effects of zinc in states such as ischemia and to determine how Zn2+ can be used to probe the mechanism of complex I. Zn2+ inhibits complex I more strongly than Mg2+, Ca2+, Ba2+, and Mn2+ to Cu2+ or Cd2+. It does not inhibit NADH oxidation or intramolecular electron transfer, so it probably inhibits either proton transfer to bound quinone or proton translocation. Thus, zinc represents a new class of complex I inhibitor clearly distinct from the many ubiquinone site inhibitors. No evidence for increased superoxide production by zinc-inhibited complex I was detected. Zinc binding to complex I is mechanistically complicated. During catalysis, zinc binds slowly and progressively, but it binds rapidly and tightly to the resting state(s) of the enzyme. Reactivation of the inhibited enzyme upon the addition of EDTA is slow, and inhibition is only partially reversible. The IC50 value for the Zn2+ inhibition of complex I is high (10-50 mu M, depending on the enzyme state); therefore, complex I is unlikely to be a major site for zinc inhibition of the electron transport chain. However, the slow response of complex I to a change in Zn2+ concentration may enhance any physiological consequences.