(H)over-right-arrow+/2(e)over-bar stoichiometry of the NADH:ubiquinone reductase reaction catalyzed by submitochondrial particles
(H)over-right-arrow+/2(e)over-bar stoichiometry of the NADH:ubiquinone reductase reaction catalyzed by submitochondrial particles
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DOI：
10.1023/a:1010257630935
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发表时间：
2001-04-01
影响因子：
2.8
通讯作者：
Vinogradov, AD
中科院分区：
文献类型：
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作者：
Galkin, AS;Grivennikova, VG;Vinogradov, AD
线粒体NADH：泛醌还原酶(复合体I)催化质子向内向外转移到亚线粒体颗粒。在这里，我们描述了一种确定苯二酚受体氧化NADH偶联反应的化学计量比(H)与右箭头(+)/2E(-)(N)的方法。在有Q(1)存在的偶联粒子中加入少量NADH后，比较周围介质中NADH氧化和碱化的初始速率，得到n=4。热致失活络合物I[1，2]导致NADH氧化酶反应完全抑制，但对NADH：Q(1)-还原酶反应仅部分抑制。N-乙基马来酰亚胺(NEM)防止重新激活，从而完全阻断热失活的酶。失活的NEM处理的酶的残余NADH：Q(1)-还原酶活性与跨膜质子转移偶联(n=4)。因此，热诱导的复合体1的失活以及内源性泛醌还原的特定抑制剂(鱼藤酮、Piericidin A)并不抑制酶的质子转移活性。
Nitochondrial NADH:ubiquinone-reductase (Complex I) catalyzes proton translocation into inside-out submitochondrial particles. Here we describe a method for determining the stoichiometric ratio (H) over right arrow (+)/2e(-) (n) for the coupled reaction of NADH oxidation by the quinone accepters. Comparison of the initial rates of NADH oxidation and alkalinization of the surrounding medium after addition of small amounts of NADH to coupled particles in the presence of Q(1) gives the value of n = 4. Thermally induced deactivation of Complex I [1, 2] results in complete inhibition of the NADH oxidase reaction but only partial inhibition of the NADH:Q(1)-reductase reaction. N-Ethylmaleimide (NEM) prevents reactivation and thus completely blocks the thermally deactivated enzyme. The residual NADH:Q(1)-reductase activity of the deactivated, NEM-treated enzyme is shown to be coupled with the transmembraneous proton translocation (n = 4). Thus, thermally induced deactivation of Complex 1 as well as specific inhibitors of the endogenous ubiquinone reduction (rotenone, piericidin A) do not inhibit the proton translocating activity of the enzyme.