Excited state dynamics in photosynthetic reaction center and light harvesting complex 1.
Excited state dynamics in photosynthetic reaction center and light harvesting complex 1.
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DOI：
10.1063/1.4738953
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发表时间：
2012-08
期刊：
影响因子：
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通讯作者：
J. Strümpfer;K. Schulten
中科院分区：
文献类型：
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作者：
J. Strümpfer;K. Schulten
在光合作用中有效收获阳光的关键是第一个能量转换过程，其中电子激发建立跨膜电荷梯度。这种转化是通过光合反应中心（RC）完成的，即在这里研究的紫色光合细菌球形红细菌的情况下，周围环绕着捕光复合物1（LH 1）。RC采用六种色素分子来启动转化：四种细菌叶绿素和两种细菌脱镁叶绿素。这些色素的激发态相互作用非常强烈，同时受到周围热蛋白质环境的影响。同样，LH 1采用32细菌叶绿素在其激发态动力学的影响，强烈的相互作用之间的色素和蛋白质环境的相互作用。在RC以及在LH 1中的激发态动力学建模需要理论方法，该方法考虑颜料-颜料相互作用和颜料-环境相互作用。在本研究中，我们描述了激发动力学内的RC和激发之间的光捕获复合物1（LH 1）和RC，采用分层方程的运动方法。为了这个目的，一组模型参数，重现RC以及LH 1光谱和观察到的振荡激励动力学的RC建议。我们发现环境对LH 1-RC激发转移有显著的影响，并且激发在LH 1和RC之间非相干地转移。
Key to efficient harvesting of sunlight in photosynthesis is the first energy conversion process in which electronic excitation establishes a trans-membrane charge gradient. This conversion is accomplished by the photosynthetic reaction center (RC) that is, in case of the purple photosynthetic bacterium Rhodobacter sphaeroides studied here, surrounded by light harvesting complex 1 (LH1). The RC employs six pigment molecules to initiate the conversion: four bacteriochlorophylls and two bacteriopheophytins. The excited states of these pigments interact very strongly and are simultaneously influenced by the surrounding thermal protein environment. Likewise, LH1 employs 32 bacteriochlorophylls influenced in their excited state dynamics by strong interaction between the pigments and by interaction with the protein environment. Modeling the excited state dynamics in the RC as well as in LH1 requires theoretical methods, which account for both pigment-pigment interaction and pigment-environment interaction. In the present study we describe the excitation dynamics within a RC and excitation transfer between light harvesting complex 1 (LH1) and RC, employing the hierarchical equation of motion method. For this purpose a set of model parameters that reproduce RC as well as LH1 spectra and observed oscillatory excitation dynamics in the RC is suggested. We find that the environment has a significant effect on LH1-RC excitation transfer and that excitation transfers incoherently between LH1 and RC.