Reorganization energy of the initial electron-transfer step in photosynthetic bacterial reaction centers.
Reorganization energy of the initial electron-transfer step in photosynthetic bacterial reaction centers.
复制标题
光合细菌反应中心初始电子转移步骤的重组能。
DOI：
10.1016/s0006-3495(98)77778-1
复制
发表时间：
1998
影响因子：
3.4
通讯作者：
Warshel,A
中科院分区：
文献类型：
--
作者：
Parson,WW;Chu,ZT;Warshel,A
利用分子动力学模拟方法研究了光合细菌反应中心电子从主电子供体（P*）向相邻细菌叶绿素（B）转移的重组能（λ）。相对较长（40 ps）的分子动力学轨道，而不是自由能微扰技术。当反应中心的周围被模拟为膜时，发现P*B → P+B−的λ为约1.6 kcal/mol。结果对蛋白质的可电离基团的处理不敏感，但用水包围反应中心会产生较高的λ值（约6.5 kcal/mol）。根据P+B−的能量略低于P* 的证据，用膜模型得到的小λ与光化学电荷分离的速度和温度无关性是一致的。计算的重组能小于预期的，如果分子动力学轨迹采样的系统的整个构象空间。由于系统在电子转移的时间尺度上没有完全弛豫，因此这里获得的λ可能比完全平衡系统获得的较大值更相关。
The reorganization energy (λ) for electron transfer from the primary electron donor (P*) to the adjacent bacteriochlorophyll (B) in photosynthetic bacterial reaction centers is explored by molecular-dynamics simulations. Relatively long (40ps) molecular-dynamics trajectories are used, rather than free energy perturbation techniques. When the surroundings of the reaction center are modeled as a membrane,λfor P*B → P+B−is found to be ∼1.6 kcal/mol. The results are not sensitive to the treatment of the protein's ionizable groups, but surrounding the reaction center with water gives higher values ofλ(∼6.5 kcal/mol). In light of the evidence that P+B−lies slightly below P* in energy, the smallλobtained with the membrane model is consistent with the speed and temperature independence of photochemical charge separation. The calculated reorganization energy is smaller than would be expected if the molecular dynamics trajectories had sampled the full conformational space of the system. Because the system does not relax completely on the time scale of electron transfer, theλobtained here probably is more pertinent than the larger value that would be obtained for a fully equilibrated system.