Excitonic Coupling on a Heliobacterial Symmetrical Type-I Reaction Center: Comparison with Photosystem I
Excitonic Coupling on a Heliobacterial Symmetrical Type-I Reaction Center: Comparison with Photosystem I
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DOI：
10.1021/acs.jpcb.9b11290
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发表时间：
2020-01-16
影响因子：
3.3
通讯作者：
Kimura, Akihiro
中科院分区：
文献类型：
--
作者：
Kitoh-Nishioka, Hirotaka;Shigeta, Yasuteru;Kimura, Akihiro
计算了 54 种细菌绿叶素-g (BChl)-g、4 种 BChl-g' 和 2 种 Chl-a(F) 色素在 Heliobacteriummodecaldum (hRC) I 型同二聚反应中心 (RC) 中的激子耦合，并与光系统 I (PSI) I 型异二聚反应中心 (RC) 中的激子耦合进行了比较。静电势跃迁电荷 (TrESP) 与泊松方程 (Poisson-TrESP) 的先进组合首次应用于激子耦合计算，给出了可靠的模型，而通过简单的标准偶极子-偶极子相互作用近似计算的模型对 hRC 定性有效，但对 PSI 无效。计算对 RC 激子耦合的长程贡献的最简单方法是 TrESP 方法，该方法考虑与距离和方向无关的局部场/屏蔽校正因子。 hRC 中的 P800 和 PSI 中的 P700 等特殊对的激子耦合也通过构型相互作用单原子 (CIS) 水平的碎片激发差分方案计算，该方案考虑了相关激子态的电荷转移特性。计算发现 P800 和 P700 的报告参数值优于 Poisson-TrESP 计算。 Chl-a和BChl-g在hRC和PSI上的虚拟交换表明hRC和PSI之间的差异源于Chl-a和BChl-g色素本身的电子结构不同以及hRC和PSI上的不同排列。还讨论了激子耦合对 hRC 和 PSI 的功能特性和进化修饰的贡献。
The excitonic couplings among 54 bacteriochlor-ophylls-g (BChl)-g, 4 BChl-g', and 2 Chl-a(F) pigments were calculated in the type-I homodimeric reaction center (RC) of Heliobacterium modesticaldum (hRC) and compared with those in the photosystem I (PSI) type-I heterodimeric RC. The advanced combination of transition charge of electrostatic potential (TrESP) with the Poisson equation (Poisson-TrESP), applied for the first time to the excitonic coupling calculation, gave a reliable model in contrast to a model calculated by simple standard dipole-dipole interaction approximation that was qualitatively valid for hRC but not for PSI. The simplest method for the calculation of the long-range contribution to the excitonic coupling on RCs is shown to be the TrESP method, which considers a distance-and orientation-independent local-field/screening correction factor. The excitonic couplings of the special pairs, P800 in hRC and P700 in PSI, are also calculated by the fragment excitation difference scheme at the configuration-interaction singles (CIS) level, which considers the charge-transfer characteristics of the relevant excitonic states. The calculation realized that the reported parameter values for P800 and P700 were better than the Poisson-TrESP calculation. Virtual exchanges between Chl-a and BChl-g on hRC and PSI indicated that the difference between hRC and PSI arises from the different electronic structures of Chl-a and BChl-g pigments themselves and the different arrangements on hRC and PSI. The contributions of excitonic couplings to the functional properties and evolutionary modifications of hRC and PSI are also discussed.