Reaction mechanism of bovine heart cytochrome c oxidase.
Reaction mechanism of bovine heart cytochrome c oxidase.
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DOI：
10.1016/j.bbabio.2006.04.028
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发表时间：
2006-05
期刊：
影响因子：
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通讯作者：
S. Yoshikawa;K. Muramoto;K. Shinzawa-Itoh;H. Aoyama;T. Tsukihara;T. Ogura;K. Shimokata;Y. Katayama;H. Shimada
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文献类型：
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作者：
S. Yoshikawa;K. Muramoto;K. Shinzawa-Itoh;H. Aoyama;T. Tsukihara;T. Ogura;K. Shimokata;Y. Katayama;H. Shimada
牛心脏细胞色素c氧化酶o2还原位点在完全还原状态下的1.9 Å分辨率x射线结构表明CuBby三个组氨酸残基的平面三角形配位。三个组氨酸残基中的一个与酪氨酸残基有共价连接，以确保酪氨酸保留在o2还原位点。这些部分促进氧的四电子还原，并防止活性氧的形成。位于酶分子膜间表面附近的天冬氨酸残基（Asp51）的氧化还原偶联构象变化以及连接Asp51与基质表面的氢键网络的存在表明质子泵送过程是在Asp51介导的。利用含有Asp51酶亚基产率的基因表达系统进行突变分析，结果支持了Asp51在质子泵送过程中起关键作用的提议。
The 1.9 Å resolution X-ray structure of the O2reduction site of bovine heart cytochrome c oxidase in the fully reduced state indicates trigonal planar coordination of CuBby three histidine residues. One of the three histidine residues has a covalent link to a tyrosine residue to ensure retention of the tyrosine at the O2reduction site. These moieties facilitate a four electron reduction of O2, and prevent formation of active oxygen species. The combination of a redox-coupled conformational change of an aspartate residue (Asp51) located near the intermembrane surface of the enzyme molecule and the existence of a hydrogen bond network connecting Asp51 to the matrix surface suggest that the proton-pumping process is mediated at Asp51. Mutation analyses using a gene expression system of the Asp51-containing enzyme subunit yield results in support of the proposal that Asp51 plays a critical role in the proton pumping process.