Viscosity dependence of the electron transfer rate from bound cytochrome c to P840 in the photosynthetic reaction center of the green sulfur bacterium Chlorobium tepidum.
Viscosity dependence of the electron transfer rate from bound cytochrome c to P840 in the photosynthetic reaction center of the green sulfur bacterium Chlorobium tepidum.
复制标题
绿色硫细菌温热绿菌光合反应中心中从结合细胞色素 c 到 P840 的电子转移速率的粘度依赖性。
作者：
H. Oh;M. Iwaki;S. Itoh
从绿色硫细菌Chlorobium tepidum纯化的反应中心复合物的结合细胞色素c和主要供体细菌叶绿素二聚体（P840）之间的反应速率中发现异常高的粘度依赖性。细胞色素具有一级结构，N-末端三个跨膜螺旋连接至延伸的C-末端含血红素的亲水部分。在295 K下，随着甘油浓度从0增加到60%（v/v），反应速率常数从5.0 × 10（3）s-1减小到1.0 × 10（3）s-1，与比粘度的-2.4次方成线性关系。甘油效应是完全可逆的。非常高的粘度依赖性不能解释的简单的扩散布朗波动模型，并表明，电子转移机制是依赖于独特的构象波动的血红素含部分的细胞色素c。
Anomalous high viscosity dependence was found in the rate of reaction between the bound cytochrome c and the primary donor bacteriochlorophyll dimer (P840) of the reaction center complex purified from the green sulfur bacterium Chlorobium tepidum. The cytochrome has a primary structure with the N-terminal three membrane-spanning helices connected to the extended C-terminal heme-containing hydrophilic moiety. The rate constant of the reaction decreased from 5.0 x 10(3) s-1 to 1.0 x 10 s-1 as the glycerol concentration increased from 0 to 60% (v/v) at 295 K, showing a linear dependence on the -2.4th power of the specific viscosity. The glycerol effect was fully reversible. The extraordinary high viscosity dependence cannot be explained by the simple diffusive Brownian fluctuation model and suggests that the electron transfer mechanism is dependent on the unique conformational fluctuations of the heme-containing moiety of cytochrome c.