Protein-Protein Orientation and Dynamics in Electron-Transfer Reactions

本研究的目的是了解静电（非共价）蛋白/蛋白复合物中电子转移的机制。将利用完全表征的金属蛋白细胞色素c （cyt）和质体青素（pc）来研究最佳反应速率和特异性的分子基础。基于该实验室最近的成功，提出了一个详细的计划，结合分子生物学（pc突变），计算化学（电子转移路径分析）和动力学（激光闪光光解），以实现以下目标：(1)确定cyt/pc复合物的反应取向；(2)确定血红素到Cu位点的显性转移路径；(3)研究远距离电子耦合的变化如何控制电子转移速率；(4)确定cyt/pc配合物的结构重排速率，建立“门控”的动力学要求；(5)探讨蛋白质/蛋白质界面构象波动对电子转移的重要性。这项研究很重要，因为金属蛋白的电子转移反应对各种生物过程至关重要。这些反应与动物代谢和植物光合作用有关。在分子水平上对电子转移有更深入的了解，对于更好地理解活细胞中化学能的起源和转化是必要的。＊＊＊

9222741 Kostic The objective of this research is to understand the mechanism of electron transfer in electrostatic (noncovalent) protein/protein complexes. The molecular basis for the optimal reaction rate and specificity will be studied with the fully-characterized metalloproteins cytochrome c (cyt) and plastocyanin (pc). Building upon this laboratory's recent successes, a detailed plan is proposed that combines molecular biology (mutation of pc), computational chemistry (analysis of electron-transfer paths), and kinetics (laser flash photolysis) in order to achieve the following: (1) determine reactive orientations of cyt/pc complexes; (2) pinpoint dominant transfer paths from the heme to the Cu site; (3) examine how variations in distant electronic couplings controls the rate of electron transfer; (4) determine the rate of structural rearrangement of cyt/pc complexes and establish kinetic requirements for "gating"; and (5) explore the importance for electron transfer of conformational fluctuations at the protein/protein interface. %%% This research is important because electron-transfer reactions of metalloproteins are essential to various biological processes. These reactions are involved in animal metabolism and plant photosynthesis. A deeper understanding of electron transfer, at the molecular level, is necessary for a better understanding of the origin and transformations of chemical energy in a living cell. ***