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