Lin Jianping, Beratan David N
Departments of Chemistry and Biochemistry, Duke University, Durham, North Carolina 27708, USA.
J Phys Chem B. 2005 Apr 21;109(15):7529-34. doi: 10.1021/jp045417w.
Electron transfer is essential for bacterial photosynthesis which converts light energy into chemical energy. This paper theoretically studies the interprotein electron transfer from cytochrome c(2) of Rhodobacter capsulatus to the photosynthetic reaction center of Rhodobacter sphaeroides in native and mutated systems. Brownian dynamics is used with an exponential distance-dependent electron-transfer rate model to compute bimolecular rate constants, which are consistent with experimental data when reasonable prefactors and decay constants are used. Interestingly, switching of the reaction mechanism from the diffusion-controlled limit in the native proteins to the activation-controlled limit in one of the mutants (DK(L261)/KE(C99)) was found. We also predict that the second-order rate for the native reaction center/cytochrome c(2) system will decrease with increasing ionic strength, a characteristic of electrostatically controlled docking.
电子转移对于将光能转化为化学能的细菌光合作用至关重要。本文从理论上研究了在天然和突变体系中，红假单胞菌细胞色素c(2)向球形红细菌光合反应中心的蛋白质间电子转移。采用布朗动力学结合指数距离依赖电子转移速率模型来计算双分子速率常数，当使用合理的预因子和衰减常数时，该常数与实验数据一致。有趣的是，发现反应机制从天然蛋白质中的扩散控制极限转变为其中一个突变体（DK(L261)/KE(C99)）中的活化控制极限。我们还预测，天然反应中心/细胞色素c(2)体系的二级速率将随着离子强度的增加而降低，这是静电控制对接的一个特征。
