Short-Range Protein Electron Transfer

电子转移是生物中普遍存在的一种现象，对多种生物活动如化学能的转化、催化酶反应、触发生物信号等都是必不可少的。黄素酶的电子传递直接参与细胞内的抗氧化剂代谢，是生命所必需的。为了在分子水平上理解蛋白质的电子转移反应，人们在实验和理论上都做出了很大的努力来理解蛋白质中电子是如何从一边隧道到另一边的。在远距离(大于10埃)，研究表明，电子在蛋白质中以与在介电介质中类似的方式在纳秒或更长的时间尺度上隧道。在近距离，由于蛋白质运动非常快，电子隧穿将受到其涨落的很大影响。使用一台类似相机的超快仪器，以百万分之一秒的速度记录电子运动的每一个时刻，就可以绘制出电子转移的动力学图。利用现代分子生物学，也可以实现对电子运动的操纵。这一融合了物理学、化学和生物学的跨学科项目将在生物过程化学方面带来新的发现和新的概念，并培养新一代年轻的跨学科科学家。通过这一奖项，化学系的生命过程化学项目资助俄亥俄州立大学的钟东平博士系统地研究短距离电子转移动力学。利用超快光谱和分子突变方法，将通过设计一系列改变转移分离的突变体来表征不同短距离下的电子转移反应的动力学。我们将研究局部蛋白质的波动，以定量分析电子转移与局部蛋白质运动的耦合。这种耦合的非平衡动力学是蛋白质动力学的中心，对生命过程是必不可少的。通过开发几个分析模型，将定量地评估局部蛋白质波动如何调制短程电子转移动力学。这些研究将是第一次系统地研究蛋白质中的短程电子转移动力学，并对理解电子如何短程隧道做出重大贡献，这是生物过程中化学的一个中心主题。这个项目也是由化学系的化学结构动力学和机制计划共同资助的。

Electron transfer is ubiquitous in biology and essential to a variety of biological activities such as converting chemical energy, catalyzing enzymatic reactions, and triggering biological signaling. Electron transfer in flavoenzymes is directly involved in intracellular antioxidant metabolism and is essential to life. To understand protein electron-transfer reactions at the molecular level, significant efforts have been made both experimentally and theoretically to understand how electrons tunnel from one side to the other side in proteins. At the long-range distance (larger than 10 Angstrom), studies have shown that an electron tunnels in proteins on a timescale of nanoseconds or longer in a similar way as in dielectric media. At the short-range distance, because the protein movements are very fast, electron tunneling will be highly affected by their fluctuations. Using an ultrafast instrument similar to a camera to record every moment of electron motions in billionth of millionth of a second, the dynamics of electron transfer can be mapped out. With modern molecular biology, the manipulation of electron motions can also be achieved. This interdisciplinary project, integrating physics, chemistry and biology, will lead to new discoveries and new concepts in the chemistry of biological processes and train a new generation of young interdisciplinary scientists. With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Dongping Zhong from The Ohio State University to systematically investigate electron-transfer dynamics at short distances. Using ultrafast spectroscopy and molecular mutation methods, the dynamics of electron-transfer reactions at different short distances will be characterized through a series of designed mutants that will vary the transfer separation. The local protein fluctuations will be examined to quantitatively analyze the coupling of electron transfer with local protein motions. Such coupled nonequilibrium dynamics is central to protein dynamics and is essential to life processes. By developing several analytical models, how short-range electron transfer dynamics are modulated by local protein fluctuations will be quantitatively evaluated. These studies will be the first to systematically study short-range electron transfer dynamics in proteins and make significant contributions to understanding how electron tunnels at a short range, a central topic to chemistry in biological processes.This project is also co-funded by the Chemical Structure Dynamics and Mechanisms Program in the Chemistry Division.