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首页> 外文期刊>Journal of photochemistry and photobiology, C. Photochemistry reviews >Primary processes in plant photosynthesis: photosystem I reaction center
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Primary processes in plant photosynthesis: photosystem I reaction center

机译：植物光合作用的主要过程：光系统I反应中心

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The photosystem I (PSI) pigment-protein complex of plants converts light energy into a transmembrane charge separation, which ultimately leads to the reduction of carbon dioxide. Recent studies on the dynamics of primary energy transfer, charge separation, and following electron transfer of the reaction center (RC) of the PSI prepared from spinach are reviewed. The main results of femtosecond transient absorption and fluorescence spectroscopies as applied to the P700-enchied PSI RC are summarized. This specially prepared material contains only 12-14 chlorophylls per P700, which is a special pair of chlorophyll a and has a significant role in primary charge separation. The P700-enriched particles are useful to study dynamics of cofactors, since about 100 light-harvesting chlorophylls are associated with wild PSI RC and prevent one from observing the elementary steps of the charge separation. In PSI RC energy and electron transfer were found to be strongly coupled and an ultrafast up-hill energy equilibration and charge separation were observed upon preferential excitation of P700. The secondary electron-transfer dynamics from the reduced primary electron acceptor chlorophyll a to quinone are described. With creating free energy differences (ΔG_0) for the reaction by reconstituting various artificial quinones and quinoids, the rate of electron transfer was measured. Analysis of rates versus ΔG_0 according to the quantum theory of electron transfer gave the reorganization energy, electronic coupling energy and other factors. It was shown that the natural quinones are optimized in the photosynthetic protein complexes. The above results were compared with those of photosynthetic purple bacteria, of which the structure and functions have been studied most.
机译：植物的光系统I（PSI）色素-蛋白质复合物将光能转换为跨膜电荷分离，最终导致二氧化碳的减少。综述了关于菠菜制备的PSI反应中心（RC）的一次能量转移，电荷分离和电子转移动力学的最新研究。总结了飞秒瞬态吸收和荧光光谱的主要结果，这些结果应用于P700增强的PSI RC。这种特殊制备的材料每个P700仅包含12-14个叶绿素，这是一对特殊的叶绿素a，在一次电荷分离中起重要作用。富含P700的颗粒可用于研究辅因子的动力学，因为约有100个采光的叶绿素与野生的PSI RC相关联，并且阻止了人们观察电荷分离的基本步骤。在PSI中，发现RC能量和电子转移紧密耦合，并且优先激发P700时观察到超快的上坡能量平衡和电荷分离。描述了从还原的一级电子受体叶绿素a到醌的二级电子转移动力学。通过重构各种人工醌和醌，在反应中产生自由能差（ΔG_0），从而测量了电子转移速率。根据电子转移的量子理论分析速率对ΔG_0的影响，给出了重组能，电子耦合能和其他因素。结果表明，在光合作用蛋白复合物中天然醌得到了优化。将以上结果与光合紫色细菌的结构和功能进行了比较研究。

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