Dispersed polaron simulations of electron transfer in photosynthetic reaction centers.
Dispersed polaron simulations of electron transfer in photosynthetic reaction centers.
复制标题
光合作用反应中心电子转移的分散极化子模拟。
DOI：
10.1126/science.2675313
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Parson,WW
中科院分区：
文献类型：
--
作者：
Warshel,A;Chu,ZT;Parson,WW
提出了一种模拟生物电子转移反应中量子力学、核隧穿效应的微观方法，并将其应用于光合细菌反应中心的几个电子转移步骤。在这种“分散极化子”方法中，蛋白质和电子载流子的波动作为有效的正模投射到适当的反应坐标上，并用于计算量子力学速率常数。模拟基于绿假单胞菌反应中心的晶体结构，重点关注从细菌叶绿素到醌的电子转移以及随后的反反应。这两种反应的速率几乎与温度无关，甚至随温度的降低而增加。模拟以定性的方式再现了这种不寻常的温度依赖性，而没有使用蛋白质的弗兰克-康登因子的可调节参数。还再现了观察到的反反应对反应自由能的依赖，包括“倒转区”中的特殊行为。
A microscopic method for simulating quantum mechanical, nuclear tunneling effects in biological electron transfer reactions is presented and applied to several electron transfer steps in photosynthetic bacterial reaction centers. In this "dispersed polaron" method the fluctuations of the protein and the electron carriers are projected as effective normal modes onto an appropriate reaction coordinate and used to evaluate the quantum mechanical rate constant. The simulations, based on the crystallographic structure of the reaction center fromRhodopseudomonas viridis, focus on electron transfer from a bacteriopheophytin to a quinone and the subsequent back-reaction. The rates of both of these reactions are almost independent of temperature or even increase with decreasing temperature. The simulations reproduce this unusual temperature dependence in a qualitative way, without the use of adjustable parameters for the protein's Franck-Condon factors. The observed dependence of the back-reaction on the free energy of the reaction also is reproduced, including the special behavior in the "inverted region."