Redox-linked proton translocation in cytochrome oxidase: the importance of gating electron flow. The effects of slip in a model transducer.
Redox-linked proton translocation in cytochrome oxidase: the importance of gating electron flow. The effects of slip in a model transducer.
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细胞色素氧化酶中氧化还原连接的质子易位：门控电子流的重要性。
DOI：
10.1016/s0006-3495(86)83511-1
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发表时间：
1986
影响因子：
3.4
通讯作者：
Chan,SI
中科院分区：
文献类型：
--
作者：
Blair,DF;Gelles,J;Chan,SI
在线粒体呼吸链的至少一种组分中，细胞色素c氧化酶，放热电子转移反应用于驱动矢量质子转运，对抗穿过线粒体内膜的电化学氢离子梯度。已经探索了电子的门控（电子转移进入和离开质子传输位点的速率的调节）在电子转移和质子泵送之间的这种耦合中的作用。该方法涉及与质子泵模型相关的稳态速率方程的求解，该模型在不同程度上包括非耦合（即，与质子泵无关）电子转移过程，其可能发生在任何真实的电子转移驱动的质子泵中。该分析为研究质子结合位点pKas和金属中心还原电位的变化的影响、能量守恒效率和周转率之间的关系、最大功率输出或最小产热的条件以及所需的电子门控效率提供了一个定量框架。通过分析得出了一些新的结论，包括：一个有效的电子转移驱动的质子泵不需要表现出pH依赖的还原电位，有效的电子转移驱动的质子泵需要非常有效的电子门控，特别是当电子转移速率和电子转移放能之间存在合理的相关性时;考虑到电子门控的重要性和可能的机制，表明在细胞色素氧化酶中通过CuA的有效质子泵送原则上可以发生限制在铜离子附近的结构变化，而通过Fea的质子泵可能需要铁和酶中更远的结构之间的构象偶联。的结论进行了讨论，参考质子泵细胞色素c氧化酶，并指出氧化磷酸化的一些可能的影响。
In at least one component of the mitochondrial respiratory chain, cytochrome c oxidase, exothermic electron transfer reactions are used to drive vectorial proton transport against an electrochemical hydrogen ion gradient across the mitochondrial inner membrane. The role of the gating of electrons (the regulation of the rates of electron transfer into and out of the proton transport site) in this coupling between electron transfer and proton pumping has been explored. The approach involves the solution of the steady-state rate equations pertinent to proton pump models which include, to various degrees, the uncoupled (i.e., not linked to proton pumping) electron transfer processes which are likely to occur in any real electron transfer-driven proton pump. This analysis furnishes a quantitative framework for examining the effects of variations in proton binding site pKas and metal center reduction potentials, the relationship between energy conservation efficiency and turnover rate, the conditions for maximum power output or minimum heat production, and required efficiency of the gating of electrons. Some novel conclusions emerge from the analysis, including: An efficient electron transfer-driven proton pump need not exhibit a pH-dependent reduction potential; Very efficient gating of electrons is required for efficient electron transfer driven proton pumping, especially when a reasonable correlation of electron transfer rate and electron transfer exoergonicity is assumed; and A consideration of the importance and possible mechanisms of the gating of electrons suggests that efficient proton pumping by CuA in cytochrome oxidase could, in principle, take place with structural changes confined to the immediate vicinity of the copper ion, while proton pumping by Fea would probably require conformational coupling between the iron and more remote structures in the enzyme. The conclusions are discussed with reference to proton pumping by cytochrome c oxidase, and some possible implications for oxidative phosphorylation are noted.
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
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DOI：
--
发表时间：
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期刊：
影响因子：
--
作者：
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影响因子：
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作者：
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