Light-induced structural changes in photosynthetic reaction center: Implications for mechanism of electron-proton transfer
Light-induced structural changes in photosynthetic reaction center: Implications for mechanism of electron-proton transfer
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DOI：
10.1126/science.276.5313.812
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发表时间：
1997-05-02
期刊：
影响因子：
56.9
通讯作者：
Feher, G
中科院分区：
文献类型：
--
作者：
Stowell, MHB;McPhillips, TM;Feher, G
高分辨率的X射线衍射数据从晶体的Rhodobacter sphaeroides光合反应中心（RC）已收集在低温下在黑暗中和在照明下，和结构细化在2.2和2.6埃分辨率，分别。在电荷分离的D（+）Q（A）Q（B）（-）态中（其中D是初级电子供体（细菌叶绿素二聚体），Q（A）和Q（B）分别是初级和次级醌受体），Q（B）（-）位于离电荷中性（DQ（A）Q（B））板中的Q（B）位置约5埃处，并且已经经历了围绕异戊二烯链的180度螺旋桨扭转。提出了一个基于两种结构之间的差异的模型来解释所观察到的从Q（A）-Q（B）到Q（A）Q（B）（-）的电子转移动力学以及Q（B）口袋中不同泛醌物种的相对结合亲和力。此外，几个水通道（推定的质子途径）导致从Q（B）口袋的RC的表面被划定，其中一个直接导致的膜表面。
High resolution x-ray diffraction data from crystals of the Rhodobacter sphaeroides photosynthetic reaction center (RC) have been collected at cryogenic temperature in the dark and under illumination, and the structures were refined at 2.2 and 2.6 angstrom resolution, respectively. In the charge-separated D(+)Q(A)Q(B)(-) state (where D is the primary electron donor (a bacteriochlorophyll dimer), and Q(A) and Q(B) are the primary and secondary quinone accepters, respectively), Q(B)(-) is located approximately 5 angstroms from the Q(B) position in the charge-neutral (DQ(A)Q(B)) slate, and has undergone a 180 degrees propeller twist around the isoprene chain. A model based on the difference between the two structures is proposed to explain the observed kinetics of electron transfer from Q(A)-Q(B) to Q(A)Q(B)(-) and the relative binding affinities of the different ubiquinone species in the Q(B) pocket. In addition, several water channels (putative proton pathways) leading from the Q(B) pocket to the surface of the RC were delineated, one of which leads directly to the membrane surface.