ELECTRON-TUNNELING PATHWAYS IN PROTEINS
ELECTRON-TUNNELING PATHWAYS IN PROTEINS
复制标题
蛋白质中的电子传递途径
DOI：
10.1126/science.1334572
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发表时间：
1992-12-11
期刊：
影响因子：
56.9
通讯作者：
GRAY, HB
中科院分区：
文献类型：
--
作者：
BERATAN, DN;ONUCHIC, JN;GRAY, HB
电子转移（ET）反应是光合作用、呼吸、药物代谢和许多其他生化过程的关键步骤。这些 ET 过程通常发生在蛋白质结合的假体基团之间，这些假体基团之间的分子距离较大（通常大于 10 A）。尽管 r--l 中的电子供体和受体预计为 0 弱耦合，但 ET 非常快，并且以高特异性进行。 14.8][28.8 A] His62 。在本期第 1748 页，PelletierandKraut (1) 介绍了关于细胞色素 c-细胞色素 c 过氧化物酶复合物晶体结构的研究，这可能会导致人们更深入地了解介入介质如何控制蛋白间 ET 反应。多年来，理论家们一直对长程蛋白质 ET 反应非常感兴趣。在标准配方中，远距离供体和受体位点之间的弱电子耦合导致速率与蛋白质介导的电子耦合因子 1TDA 1 2 以及与 ET 过程耦合的核运动产生的核因子成正比 (2)。描述长程蛋白质 ET 的最简单模型将供体和受体之间的介质视为一维方形隧道势垒 (IDSB)；因此，预测速率 (kET) 将随着距离 (3, 4) 呈指数下降。考虑 1DSB 模型中蛋白质介导的耦合的作用相当于为电子隧道指定势垒高度。 Hopfield (1.4 AI)(3) 和 Jortner (2.6 AI)(4) 在 20 世纪 70 年代对指数衰减常数 (P) 的估计刺激了许多关于小分子和蛋白质的实验。长程 ET 中电子耦合问题的简单表述将供体和受体之间的介质描述为由相同重复单元组成的桥梁：
Electron-transfer (ET) reactions are key steps in photosynthesis, respiration, drug metabolism, and many other biochemical processes. These ET processes commonly occur between protein-bound prosthetic groups that are separated by~:,"" large molecular distances (often~ greater than 10 A). Although the electron donors and acceptors in r--l these reactions are expected to be 0 weakly coupled, the ETs are remark- 14.8][28.8 A] His62 ably fast and proceed with high specificity. On page 1748 of this issue, PelletierandKraut (1) present work on the crystal structures of cytochrome c--eytochrome c peroxidase complexes that could lead to a much deeper understanding of how the intervening medium controls interprotein ET reactions. Theoreticians have been intensely interested in long-range protein ET reactions for many years. In standard formulations, the weak electronic coupling between distant donor and acceptor sites leads to rates that are proportional to a protein-mediated electronic-coupling factor, 1TDA 1 2, and a nuclear factor that arises from nuclear motion coupled to the ET process (2). The simplest models describing long-range protein ET treat the medium between donor and acceptor as a one-dimensional square tunneling barrier (IDSB); accordingly, the rate (kET) is predicted to drop exponentially with distance (3, 4). Accounting for the role of proteinmediated coupling in the 1DSB models amounts to assigning a barrier height for electron tunneling. Estimates of the exponential decay constants (P) made in the 1970s by Hopfield (1.4 AI)(3) and Jortner (2.6 AI)(4) stimulated numerous experiments on small molecules and proteins. A simple formulation of the electroniccoupling problem in long-range ET describes the medium between donor and acceptor as a bridge comprised of identical repeat units: