Theory and Calculations of Electron Transfer in Protein Media

蛋白质介质中电子转移的理论与计算

基本信息

批准号：
17570137
负责人：
KAKITANI Toshiaki
金额：
$ 2.37万
依托单位：
Meijo University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

(1) We investigated the mechanism of electron transfer (ET) in protein environment, by taking an example of ET of bacteriopheophitin anion to primary quinine in the reaction center of photosynthetic bacteria by the combined study of molecular dynamics simulations and quantum chemistry. (2)We found that electronic tunneling matrix element of the ET rate is varied by a few orders of magnitude according to the thermal fluctuation of the protein conformation. (3) We found that the origin of the large variation is mostly fluctuations of amino acid conformation rather than the fluctuation of donor-acceptor distance. (4) We found that there exist two main tunneling routes with opposite tunneling currents, bringing about a large amount of destructive quantum interference. (5)We developed a new non-Condon theory which is usable when the electronic factor of the ET is varied very quickly. As a result, we derived the formula describing the ET rate as a sum of the two terms: The first is the ET rate due to the elastic electron tunneling mechanism in which the electron energy is conserve before and after ET. This mechanism corresponds to the ordinary ET theory. The second is the ET rate due to the inelastic electron tunneling mechanism in which the electron energy is not conserved before and after ET. The absorbed or emitted energy is due to the frequency of Fourier transform for the fluctuation of electron tunneling matrix element. (6) By numerical calculations, we found that the inelastic tunneling mechanism works appreciably at the substantial inverted region of the Marcus energy gap law. (7) We invented a new method for properly averaging the fluctuation to obtain the average tunneling route, involving the effect of quantum interference effect.

（1）我们通过以分子动力学仿真和量子化学的联合研究为光合作用细菌反应中心的原代奎宁进行了蛋白质环境的ET的例子，研究了蛋白质环境中电子转移（ET）的机制。（2）我们发现，根据蛋白质构象的热波动，ET速率的电子隧穿矩阵元素因几个数量级而变化。（3）我们发现大变化的起源主要是氨基酸构象的波动，而不是供体距离距离的波动。（4）我们发现存在两个带有相反隧穿电流的主要隧道路线，从而带来了大量破坏性的量子干扰。（5）我们开发了一种新的非康复理论，当ET的电子因素变化很快时，它是可用的。结果，我们得出了将ET速率描述为两个术语的总和的公式：第一个是ET速率，这是由于弹性电子隧道隧穿的机制，其中电子能在ET之前和之后保存。该机制对应于普通的ET理论。第二个是由于非弹性电子隧穿机制引起的ET速率，其中电子能在ET之前和之后无法保守。吸收或发射的能量是由于电子隧穿矩阵元件波动的傅立叶变换的频率。（6）通过数值计算，我们发现非弹性隧道机制在Marcus Energy Gap定律的实质性倒置区域明显起作用。（7）我们发明了一种新方法，用于正确平均波动以获得平均隧道途径，涉及量子干扰效应的效果。