Short-Range Protein Electron Transfer

Ohio State University, The, Columbus OH

Investigators

Abstract

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.