Electron Transfer in Cytochromes: Controlling Factors

这项工作的长期目标是描述控制生物系统中电子转移的因素，特别是在细胞色素c和b5中。(1)通过研究静电表面改变的细胞色素来评价蛋白质表面电荷的作用。(2)电子转移的速率常数被认为随距离呈指数下降；这种距离依赖关系可能反过来又是反应驱动力的函数。狄克逊博士将制造一系列细胞色素b5。随着电子转移位上空间体积的增加。将测量不同驱动力下的速率常数。由此得到的速率常数矩阵将被用来评估电子转移对距离和驱动力的依赖性。(3)Dixon博士将使用核磁共振技术测量一系列细胞色素c的电子转移速率常数和蛋白质运动，以了解电子转移的构象和重组控制的分子基础。将特别强调细胞色素c的结构作为离子强度的函数，轴向蛋氨酸可逆损失的动力学，以及血红素附近残基在控制电子转移中的作用。

The long term goal of this work is to delineate the factors which control electron transfer in biological systems specifically in cytochromes c and b5. (1) The role of protein surface charges will be evaluated by studying cytochromes with altered electrostatic surfaces. (2) The rate constant for electron transfer is thought to decrease exponentially with distance; this distance dependence may in turn be a function of the driving force for the reaction. Dr. Dixon will make a series of cytochromes b5. with increasing steric bulk at the electron transfer site. Rate constants at different driving forces will be measured. The resulting matrix of rate constants will be used to assess the dependence of electron transfer on distance and driving force. (3) Dr. Dixon will use NMR techniques to measure both electron transfer rate constants and protein motions for a series of cytochromes c in an effect to understand the molecular basis of conformational and reorganizational control of electron transfer. Particular emphasis will be placed on the structure of cytochrome c as a function of ionic strength, on the kinetics of the reversible loss of the axial methionine and on the roles of residues near the heme in controlling electron transfer.