光合细菌原初反应的理论研究

选择光合细菌的原初电子供体P₈₇₀为理论研究对象 ,通过理论计算发现 :( 1 )原初电子供体的双分子结构在能量上比单分子结构更有利 ;( 2 )电荷分离之后 ,原初电子供体的原有空间构型不再是稳定的构型 ,其构型会向能量和化学活性都更低的构型转变 .在光合细菌的P₈₇₀ 中 ,这种转变通过C₃ 位的乙酰基旋转使其氧原子与另 1个细菌叶绿素a分子的镁原子相互作用 ,导致P^+.₈₇₀的总能量和化学活性都明显降低 .认为原初电子供体的构型在原初反应过程中的这种转变对于防止原初反应过程中的电荷重组、维持光能的高效转化有重要意义 .提出了原初反应的新模型 ,并利用这一新机理对最近的动力学和定点突变研究结果给予了较合理的解释 .     

Theoretical study on primary reaction of photosynthetic bacteria

Theoretical calculation was carried out on the primary electron donor P_(870) of photosynthetic bacteria. The results show that: (ⅰ) the bimolecular structure of the primary electron donor is more advantageous in energy than monomolecular structure; (ⅱ) the initial configuration of primary electron donor is no longer stable and changes to the configuration with lower energy and chemical reactivity after the charge separation. In the P_(870), such structural change is completed through the rotation of C_3 acetyl, so the oxygen atom of acetyl interacts with the magnesium atom of another bacterio-chlorophyll molecule, and the total energy and chemical reactivity are reduced evidently. It is suggested that the structural change of the primary electron donor is important in preventing the occurrence of charge recombination during the primary reaction and maintaining the high efficiency of the conversion of sun-light to chemical energy. A new mechanism of primary reaction has been proposed, which can give r     

Theoretical investigation on peripheral ligands of oxygen-evolving center in photosystem II

The interaction between the Mn-cluster and its peripheral ligands in oxygen-evolving center is still unclear. Theoretical investigation on the coordination of histidine, H2O, and Cl to Mn2O2 units in OEC is conducted. The following conclusions are obtained: (i) both histidine and H2O molecule, bound to the two Mn ions, respectively, are vertical to the Mn2O2 plane, and maintain a large distance; (ii) the two H2O molecules cannot bind to the same Mn2O2 unit. Based on Mn-cluster structure in OEC, we theoretically predict that two H2O molecules bind to the two Mn ions at the "C"-shaped open end in S0 state, while two His residues at the closed end. Cl ion can only terminally ligate at the open end. Individual valence for the four Mn ions in S0 state is assigned.     

固氮酶固氮机理的新观点

固氮酶固氮机理的新观点张纯喜（中国科学院福建物质结构研究所,福州３５０００２）本文提出了一个关于固氮酶固氮机理的新观点,认为在固氮酶固氮过程中,还原态的Ｐ一簇产生活泼的氢原子,活泼的氢原子部分用于产生氢气。部分用于激活ＦｅＭｏ－辅基（使氧化态的ＦｅＭ...     

光合放氧中心外围配体的理论研究

光合放氧中心外围配体如何与Mn簇结合目前很不明确. 选择放氧中心Mn2O2单元作为理论研究对象, 对组氨酸、水和Cl等配体与Mn簇的结合方式进行了研究, 得到如下结论: (1) 组氨酸和H2O分子应与Mn2O2平面垂直, 彼此保持较大的距离, 且结合于不同Mn离子上; (2) 两个H2O分子不可能结合在同一个Mn2O2单元上. 结合目前放氧中心Mn簇骨架结构, 从理论上阐明了在S0状态下, 两个水分子与放氧中心"C"形结构开口端的两个Mn离子结合, 两个组氨酸分别与"C"形结构闭口端的两个Mn离子结合; Cl结合位点只可能在"C"形结构的开口端. 在此基础上, 对当前争议较大的Mn价态进行了归属.