Department of Physics, Graduate School of Science , Nagoya University , Nagoya 464-8602 , Japan.
J Phys Chem B. 2018 Dec 20;122(50):11852-11859. doi: 10.1021/acs.jpcb.8b08014. Epub 2018 Nov 29.
A simple theoretical model of exciton dynamics was proposed to interpret the fast excitation energy-transfer process in the type I homodimeric reaction center of Heliobacterium modesticaldum (hRC); this structure was recently identified and shown to resemble that of the plant/cyanobacterial photosystem I (PSI) reaction center. The exciton state model, which mainly relies on the geometries of 54 bacteriochlorophyll (BChl) g, 4 BChl- g', and 2 chlorophyll (Chl) a on hRC and assumes constant site energy values for the pigments, reproduced the absorption spectrum of hRC rather well. The model also enabled numerical analysis of the exciton dynamics on hRC, which can be compared with the decay-associated spectra obtained by the laser spectroscopy experiments. The model indicates that the stronger transition-dipole moment on BChl- g contributes to the faster energy transfer due to the higher coherency of the delocalized exciton states on hRC compared to that on PSI that arranges Chl- a at almost homologous locations.
我们提出了一个简单的激子动力学理论模型，以解释海栖热袍菌（Heliobacterium modesticaldum）I 型同二聚体反应中心（hRC）中快速激发能量转移过程；该结构最近被确定，并显示出与植物/蓝细菌光系统 I（PSI）反应中心相似的结构。该激子态模型主要依赖于 hRC 上 54 个细菌叶绿素（BChl）g、4 个 BChl-g'和 2 个叶绿素（Chl）a 的几何形状，并假设色素的位置能值保持不变，很好地再现了 hRC 的吸收光谱。该模型还能够对 hRC 上的激子动力学进行数值分析，并与激光光谱实验获得的衰减相关光谱进行比较。该模型表明，BChl-g 上较强的跃迁偶极矩有助于更快的能量转移，这是由于与在 PSI 上排列叶绿素 a 的几乎同源位置相比，hRC 上非定域激子态的相干性更高。
