细菌光合作用初级电荷分离的能量学和动力学
Energetics and Kinetics of Primary Charge Separation in Bacterial Photosynthesis
摘要：
我们报告的结果分子动力学（MD）模拟和正式建模的自由能表面和初级电荷分离的反应中心的\textit{Rhodobacter sphaeroides}的反应速率。两个模拟协议被用来产生MD轨迹。在第一个协议中采用标准力场电位。在第二个协议中，特殊的一对被极化，再现高极化率的斯塔克光谱观察到的光激发态。在模拟运行过程中，共价态和电荷转移态之间的电荷分布被动态调整。我们发现，从这两个协议的蛋白质/水环境的静电波动的宽度远远超过以前的估计，导致约1.6 eV的重组能量的电子转移在第一协议和2.5 eV的第二协议。这些静电波动中的大多数在主电荷分离的时间尺度上动态冻结，从而导致对活化势垒的溶剂化贡献小得多。一个非遍历制定的扩散反应电子转移动力学，使我们能够重现的速率和非指数衰减的光激发的特殊对人口的温度依赖性的实验结果。
英文摘要：
We report the results of Molecular Dynamics (MD) simulations and formal modeling of the free energy surfaces and reaction rates of primary charge separation in the reaction center of \textit{Rhodobacter sphaeroides}. Two simulation protocols were used to produce MD trajectories. Standard force field potentials were employed in the first protocol. In the second protocol, the special pair was made polarizable to reproduce a high polarizability of its photoexcited state observed by Stark spectroscopy. The charge distribution between covalent and charge-transfer states of the special pair was dynamically adjusted during the simulation run. We found from both protocols that the breadth of electrostatic fluctuations of the protein/water environment far exceeds previous estimates resulting in about 1.6 eV reorganization energy of electron transfer in the first protocol and 2.5 eV in the second protocol. Most of these electrostatic fluctuations become dynamically frozen on the time-scale of primary charge separation resulting in much smaller solvation contributions to the activation barrier. A non-ergodic formulation of the diffusion-reaction electron transfer kinetics has allowed us to reproduce the experimental results for both the temperature dependence of the rate and the non-exponential decay of the population of the photoexcited special pair.
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