Natural engineering principles of electron tunnelling in biological oxidation-reduction
Natural engineering principles of electron tunnelling in biological oxidation-reduction
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DOI：
10.1038/46972
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发表时间：
1999-11-04
期刊：
影响因子：
64.8
通讯作者：
Dutton, PL
中科院分区：
文献类型：
--
作者：
Page, CC;Moser, CC;Dutton, PL
我们已经调查了具有已知原子结构的蛋白质，其功能涉及电子转移;在这些蛋白质中，电子可以通过蛋白质介质在氧化还原中心之间行进高达14埃。在较长距离上的转移总是涉及一系列辅因子。这种氧化还原中心的接近性本身就足以允许电子以远快于其支持的底物氧化还原反应的速率隧穿。因此，蛋白质没有必要在氧化还原中心之间进化出优化的路线。相反，简单的几何结构使得能够快速隧穿到高能中间态。这大大简化了氧化还原蛋白机制的任何分析，并挑战了在研究电子转移反应时通过氧化还原中心或维持电荷中性来假设超交换机制的需要。这样的隧道效应也允许在催化位点的顺序电子转移，以克服自由基过渡态，而不涉及氢化物离子的运动，一般认为。氧化还原中心的14埃或更小的间距为电子转移提供了高度鲁棒的工程设计，并且可能反映了对在进化过程中被证明更容易受到突变影响的设计的选择。
We have surveyed proteins with known atomic structure whose function involves electron transfer; in these, electrons can travel up to 14 Angstrom between redox centres through the protein medium. Transfer over longer distances always involves a chain of cofactors. This redox centre proximity alone is sufficient to allow tunnelling of electrons at rates far faster than the substrate redox reactions it supports. Consequently, there has been no necessity for proteins to evolve optimized routes between redox centres. Instead, simple geometry enables rapid tunnelling to high-energy intermediate states. This greatly simplifies any analysis of redox protein mechanisms and challenges the need to postulate mechanisms of superexchange through redox centres or the maintenance of,charge neutrality when investigating electron-transfer reactions. Such tunnelling also allows sequential electron transfer in catalytic sites to surmount radical transition states without involving the movement of hydride ions, as is generally assumed. The 14 Angstrom or less spacing of redox centres provides highly robust engineering for electron transfer, and may reflect selection against designs that have proved more vulnerable to mutations during the course of evolution.