Theoretical study on trapping, transfer and fixation of solar radiation energy in photosynthesis of higher plants

在生物过程研究中，弄清生物聚合物的结构及其在蛋白质中的排列是重要的一步。在光合作用方面，直到1984年以后，光合细菌光系统中蛋白质-色素复合物的三维结构才首次被阐明。从那时起，光合作用的研究有了很大的发展。然而，这些细菌的光合作用使用像H2S这样的物质，而不是H2O作为起始物质，因此不会产生氧气。因此，研究高等植物参与进化氧光合作用的蛋白质-色素复合物的三维结构一直是人们所期待的。这一目标终于在2001年实现。然而，一个大问题暴露了出来。参与光合作用初始过程的生物体是反应中心和天线系统，其中核心天线最紧密地包裹着反应中心。结果表明，在无氧和有氧光合作用中，色素在核心天线中的排列有很大的差异，尽管它们在反应中心的排列相似。人们已经接受，这两种光合作用是从一个共同的祖先进化而来的，彼此分离。因此，光合作用中最重要的过程应该在这两种光合作用中几乎是共同的。这不能从天线系统的反应中心结构来理解。作为本工作最重要的成果，阐明了反应中心从核心天线捕获色素激发能，然后在反应中心迅速将激发能初始固定到电荷分离状态的机制在两种光合作用中是守恒的。这个反应在整个最初的光合作用过程中是最重要的，限制了它，如果这个反应机制发生本质的改变，光合作用就会变得困难。因此，它在进化中一定是保守的。换句话说，本研究阐明了整个初始光合过程中最重要的反应Less的机制

In research of biological processes, it is an important step to clarify the structure of biological polymers and their arrangement in proteins. In photosynthesis, it was only recent, after 1984, that 3-d structures of protein-pigment complexes in photosystems of photosynthetic bacteria were first clarified. Since then, research of photosynthesis has greatly been developed. Photosynthesis by these bacteria, however, uses substances like H2S, but H2O, as starting materials, and hence does not evolve oxygen. Accordingly, it had been awaited to clarify 3-d structures of protein-pigment complexes participating in oxygen-evolving photosynthesis by higher plants. It was finally achieved since 2001.However, a big issue reveals itself. Organisms participating in the initial processes of photosynthesis are the reaction center and the antenna system, in which the core antenna encloses most closely the reaction center. It was clarified that the arrangement of pigments in the core antenna is very d … More ifferent between anoxygenic and oxygenic kinds of photosynthesis, although that in the reaction center is similar between them. It has been accepted that these two kinds of photosynthesis have evolved from a common ancestor, departing from each other. Therefore, the most important processes essential in photosynthesis should be nearly common between these two kinds of photosynthesis. This cannot be understood from the structure of the reaction center ant the antenna system.As the most important achievement of the present work, it was clarified that the mechanism for trapping of pigment excitation energies from the core antenna by the reaction center, quickly followed by the initial fixation of excitation energies into the charge-separated state in the reaction center, is conserved between the two kinds of photosynthesis. This reaction is most important in the whole of the initial photosynthetic processes, limiting it, and photosynthesis would become difficult if this reaction mechanism was changed essentially. Accordingly, it must be conserved in evolution. In other words, the present work clarified the mechanism of the most important reaction in the whole of the initial photosynthetic processes, Less