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首页> 外文期刊>Analytical Sciences >Cytochrome Oxidase at the Membrane/Water Interface: Mechanism of Functioning and Molecular Recognition
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Cytochrome Oxidase at the Membrane/Water Interface: Mechanism of Functioning and Molecular Recognition

机译：膜/水界面的细胞色素氧化酶：作用机理和分子识别

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A concerted 2:1:1-electron mechanism for cytochrome oxidase functioning is evaluated by thermodynamic and kinetic analysis. Possible ways of dioxygen reduction to water as well as the stoichiometry of the proton pump are analyzed thermodynamically. The conditions are formulated for the occurrence of multielectron oxygen reduction. Kharkats and Volkov first presented proofs that cytochrome c oxidase reduces molecular oxygen by synchronous multielectron mechanism without O2- intermediate formation (Yu. I. Kharkats and A. G. Volkov, Biochim. Biophys. Acta, 891, 56 (1987)). As the field progresses after this pioneering observations, it became clear that the first step of dioxygen reduction is two-electron concerted process. As follows from thermodynamics energy for the H+-pump functioning is liberated only at the last two steps of water formation on addition of third and fourth electrons independently of the reaction pathway. The media reorganization energy corresponding to simultaneous electrons and protons transfer will be minimal in the case then the directions of their transfers are close. In mitochondrial cytochrome c oxidase the donor of electrons is placed on the side C and the protons comes from the side M. In this case the minimal activation energy will be achieved at maximal possible at given geometry of the system angle between the directions of electrons and protons transfer.
机译：通过热力学和动力学分析评估细胞色素氧化酶功能的协调的2：1：1电子机制。热力学分析了将双氧还原为水的可能方式以及质子泵的化学计量。规定发生多电子氧还原的条件。 Kharkats和Volkov首次提出证明，细胞色素C氧化酶通过同步多电子机制还原了分子氧，而没有O2-中间体的形成（Yu。I. Kharkats和A. G. Volkov，Biochim。Biophys。Acta，891，56（1987））。在此先驱性观察之后，随着该领域的发展，很明显，双氧还原的第一步是两电子协同过程。根据热力学，如下所述，仅在水形成的最后两个步骤中，通过添加第三和第四电子而与反应路径无关地释放用于H +泵功能的能量。在电子和质子同时转移的方向接近的情况下，与电子和质子同时转移相对应的介质重组能将最小。在线粒体细胞色素C氧化酶中，电子供体位于C侧，质子来自M侧。在这种情况下，在给定的系统方向上，在电子方向与电子方向之间的几何角度下，将以最大可能的方式获得最小的活化能。质子转移。

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