Studies on the Photochemical Reaction Center Complexes of Photosynthesis

光合作用最重要的过程之一是将光能转化为化学能的光化学反应。各种执行光化学反应的蛋白质络合物都是可用的，并在本研究中使用。主要研究结果如下：(1)蓝藻光系统II复合体--(A)光系统II复合体中的质醌被多种苯醌类化合物取代，我们发现四卤苯与光系统II复合体结合效率最高，是最有效的电子受体。(2)光系统I复合体--(A)选择性破坏光系统I复合体的FeS中心表明，FeS中心A和B都是电子传递所必需的。细菌反应中心复合体：(A)幽门螺杆菌的反应中心复合体含有两个细菌叶绿素g‘分子和两个类叶绿素a类色素分子。(2)我们研究了在水饱和的CCl_4中形成的细菌叶绿素c的单体、二聚体、三聚体和聚合物的吸收光谱和CD光谱。(4)光合作用基因--(A)我们从萌发的小麦中纯化了一种使叶绿体DNA甲醇化的酶。(B)我们克隆了编码光系统II复合体小分子多肽的叶绿体基因组基因。(C)将磷酸烯醇式丙酮酸羧化酶(PEPcase)基因的启动子区域与报告基因连接，研究了PEPcase基因的组织特异性表达。NH_3可促进PEPcase C_4型基因转录，但不能促进C_3型基因转录。

One of the most important processes of photosynthesis is the photochemical reaction that converts light energy into chemical energy. Various kinds of protein complexes, which perform the photochemical reactions, are available, and are used in this study. The results are summarized as follows : (1) Photosystem II complex - (a) Plastoquinone of the cyanobacterial photosystem II complex was substituted by many kinds of quinone derivatives, and we found that tetrahalobenzene most efficienty bound to the photosystem II complex and was a most efficient electron acceptor. (b) The oxygen-evolving activity of the photosystem II complex was greatly stabilized by glycinebetaine.(2) Photosystem I complex - (a) Selective destruction of FeS centers of the photosystem I complex demonstrated that both FeS centers A and B are essential to the electron transport. (b) In the reconstitution experiment with liposomes, it was suggested that monogalactolipid accelerates the transfer of excitation energy from the light-harvesting chlorophyll protein to the photosystem I complex.(3) Bacterial reaction center complex - (a) The reaction center complex from Heliobacterium contained two molecules of bacteriochlorophyll g' and two molecules of a chlorophyll a-like pigment. (b) We studied the absorption and the CD spectra of monomer, dimer, trimer and polymer of Bacteriochlorophyll c which were formed in water - saturated CCl_4.(4) Photosynthesis genes - (a) We purified from germinating wheat an enzyme which methanolizes plastid DNA. (b) We cloned genes of the chloroplast genome which encode small polypeptides of the photosystem II complex. (c) The tissuespecific expression of phosphoenolpyruvate carboxylase (PEPcase) was studied by ligating the promoter region of PEPcase gene with a reporter gene. The transcription of the gene for the C_4 type, but not C_3 type, of PEPcase was enhanced by NH_3.