细菌光合反应中心突变体原初电子转移机理的理 论研究

利用量子化学DFT从头计算方法，计算经过突变的细菌光合反应中心HM202L原始电子给体和其他色素分子的电子结构，然后对其原初电子转移机理进行探讨。结果表明：1)超分子D-2A的HOMO主要是由定域在其组成单元BChl~L分子上的原子轨道组成，而它的LUMO主要是由定域在其组成单元MBPheo~M分子上的原子轨道组成。这表明它在基态的激发态时分别存在超分子内的电荷分离态BChl~L^--MBPheo~M^+]和BChl~L^+-MBPheo~M^-]。同时也说明了D-2A阳离子态的正电荷完全分布在组成单元细菌叶绿素分子BChl~L上，与实验事实相符。2)HM202L细菌光合反应中心原初电子转移反应存在由ABCha~L^h^*驱动的电子转移反应。

The theoretical stucies on the machanism of the primary electron transfer in the mutant photosynthetic reaction center

The electronic structure of the primary electron donor D - 2A and other pigments in photosynthetic reaction center (RC) of the mutant HM202L of Rhodobacter sphaeroides has been studied with the ab initio DFT method. The mechanism of primary electron transfer in this mutant was studied. The results indicated 1) HOMO of super - molecule D - 2A mainly consists of the atomic orbitals of atoms located at the composition unit BChlL, and its LUMO mainly consists of atomic orbitals of atoms located at the composition unit MBPheoM. These rsults indicate that there exist internal charge separated states BChlL- MBPheoM ] and BChlL -MBPheoM- ] in the ground state and excited state of super - molecule D - 2A, respectively. The positive charge of the D - 2A cation completely localizes on the composition unit BChlL, which is in agreement with the experimental fact. 2) There might be a reaction channel, in which the primary electron transfer reaction may be driven by ABChlaLh* in the HM202L photosynthetic reaction center.