Study of Electronic Structures and Pigment-Protein Interactions in the Reaction Center of Thermochromatium tepidum with a Dynamic Environment.
Study of Electronic Structures and Pigment-Protein Interactions in the Reaction Center of Thermochromatium tepidum with a Dynamic Environment.
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DOI：
10.1021/acs.jpcb.6b06628
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发表时间：
2016-09
期刊：
影响因子：
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通讯作者：
Fulu Zheng;Meng-Yi Jin;T. Mančal;Yang Zhao
中科院分区：
文献类型：
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作者：
Fulu Zheng;Meng-Yi Jin;T. Mančal;Yang Zhao
基于最近报道的来自Thermochromatium tepidum的捕光复合物1-反应中心（LH 1-RC）复合物的X射线晶体结构，我们从理论上研究了RC复合物的电子结构和色素-蛋白质相互作用.混合量子力学/分子力学方法结合分子动力学模拟研究环境对RC辅因子的激发能的影响，考虑了动态环境。环境效应被认为是必不可少的电子结构测定。特殊的对，二聚体的细菌叶绿素作为主要的电子供体在细菌RC，是我们在这项工作中的重点。第一个激发态的特殊对被发现具有最低的激发能量的所有分子在系统中，使其最有可能填充网站后的激发转移。本文应用静电势的跃迁电荷和点偶极近似计算了单个色素之间以及特殊色素对与其它色素之间的电子耦合。PM分子与L分支色素之间的电子耦合比PM分子与M分支色素之间的电子耦合强。量子化学计算揭示了该特殊对第一激发态的电荷转移特性。因此，电荷分离沿着RC中的L分支沿着发生。还计算了所有辅因子的谱密度。
On the basis of the recently reported X-ray crystal structure of light-harvesting complex 1-reaction center (LH1-RC) complex from Thermochromatium tepidum, we investigate electronic structures and pigment-protein interactions in the RC complex from a theoretical perspective. Hybrid quantum-mechanics/molecular-mechanics methods in combination with molecular dynamics simulations are employed to study environmental effects on excitation energies of RC cofactors with the consideration of a dynamic environment. The environmental effects are found to be essential for electronic structure determination. The special pair, a dimer of bacteriochlorophylls which serves as the primary electron donor in the bacterial RC, is our focus in this work. The first excited state of the special pair is found to have the lowest excitation energy of all molecules in the system, making it the most likely populated site after the excitation transfer. The transition charges from electrostatic potentials and the point dipole approximation have been applied to calculate the electronic coupling between individual pigments and that between the special pair and other pigments. Stronger electronic coupling is obtained between the PM molecule and the L branch pigments than that between the PM and the pigments in the M branch. Quantum chemical calculations reveal charge transfer characteristics of the first excited state of the special pair. It follows that charge separation takes place along the L branch in the RC. Spectral densities for all the cofactors are also calculated.