Institut für Theoretische Physik, Johannes Kepler Universität, Altenberger Strasse 69, 4040 Linz, Austria.
Chemphyschem. 2010 Apr 26;11(6):1141-53. doi: 10.1002/cphc.200900932.
This Minireview summarizes our current knowledge of the optical properties of photosystem II (PS-II) and how these properties are related to the photosynthetic function, that is, excitation energy transfer from the antenna complexes to the reaction center (RC) and the subsequent transmembrane charge separation in the latter. Interpretation of the optical spectra of PS-II is much more difficult than for the RC of purple bacteria, due to the "spectral congestion" problem, namely, the strong spectral overlap of optical bands in PS-II. Recent developments in deciphering the optical properties of the pigments in PS-II, the identification of functional states, and the kinetic details of the primary excitation energy and charge-transfer reactions are summarized. The spectroscopic term P(680) that is generally used in the literature no longer indicates the same entity in its cationic and singlet excited form but different subsets of the six innermost pigments of the RC. The accessory chlorophyll Chl(D1) forms a sink for singlet excitation and triplet energy and most likely represents the primary electron donor in PS-II. In this respect, a special chlorophyll monomer in PS-II plays the role of the special pair in purple bacteria. Evidence that exciton transfer between the core antenna complexes CP43 and CP47 and the RC is the bottleneck for the overall photochemical trapping of excitation energy in PS-II is discussed. A short summary is provided of PS-II of Acaryochloris marina, which mainly contains chlorophyll d instead of the usual chlorophyll a. This system does not suffer from the spectral congestion problem and, therefore, represents an interesting model system. The final part of this Minireview provides a discussion of challenging problems to be solved in the future.
这篇综述总结了我们目前对光系统 II（PS-II）光学性质的了解，以及这些性质如何与光合作用功能相关，即从天线复合物到反应中心（RC）的激发能量转移，以及随后在后一种复合物中的跨膜电荷分离。与紫色细菌的 RC 相比，PS-II 光学光谱的解释要困难得多，这是由于“光谱拥挤”问题，即 PS-II 中的光学带强烈光谱重叠。最近在破译 PS-II 中色素的光学性质、鉴定功能状态以及初级激发能量和电荷转移反应的动力学细节方面的进展进行了总结。文献中通常使用的光谱术语 P(680)不再表示阳离子和单重激发形式的相同实体，而是 RC 中六个最内层色素的不同子集。辅助叶绿素 Chl(D1)形成单重激发和三重能量的汇，并且很可能代表 PS-II 中的初级电子供体。在这方面，PS-II 中的一个特殊叶绿素单体扮演了紫色细菌中特殊对的角色。讨论了 CP43 和 CP47 核心天线复合物与 RC 之间的激子转移是 PS-II 中整体光化学捕获激发能量的瓶颈的证据。简要总结了主要含有叶绿素 d 而不是通常的叶绿素 a 的 Acaryochloris marina 的 PS-II。该系统不会遭受光谱拥挤问题的困扰，因此代表了一个有趣的模型系统。这篇综述的最后一部分讨论了未来需要解决的具有挑战性的问题。
