Bacterial Reaction Centers With New Photochemical Properties

Arizona State University, Scottsdale AZ

Investigators

Abstract

Deciphering the mechanisms by which the movement of protons is linked to electron transfer is an important challenge in understanding biochemical catalysis. Professors James Allen and JoAnn Williams of Arizona State University are directing their efforts to elucidate this linkage for chemical reactions that occur in photosynthesis, nature's fundamental process for converting light into chemical energy. Because control of coupling between proton and electron transfer is critical for achieving efficient energy conversion and chemical transformations, this project aims to generate a more complete understanding of the physical principles that govern these processes in complex systems. The activities offer societal benefits through broadening participation in science and engagement of the wider community. To overcome traditional low graduation rates and limited participation in science degree programs, this project provides students from a local community college with a personal research experience in a supportive environment that encourages their continuation in science. In another avenue of engagement, students work with artists to express the scientific concepts behind research in bioenergy and photosynthesis and present their integration of science and art to the local community. With this award, the Chemistry of Life Processes Program, with partial co-funding from the Molecular Biophysics Cluster in the Division of Molecular and Cellular Biosciences, is supporting Professors James Allen and JoAnn Williams of Arizona State University to help establish molecular concepts that explain how proteins effectively perform proton-coupled, multi-electron-transfer reactions. They are using novel protein design strategies to modify the bacterial reaction center, an integral membrane protein serving as the site of the primary photochemistry in photosynthesis. The yields of proton and electron transfer are being measured for different cofactors and protein environments. The experimental methods combine structure-based protein design, enabled by molecular biology and biochemical techniques, with analysis of the properties of the resulting complexes by optical and magnetic resonance spectroscopy. The project is designed to expand the tools available for designing proton-coupled, electron-transfer reactions for catalysis in biological systems and establish a framework applicable for understanding the progression of oxidation states in the fundamental water oxidation reactions of photosystem II. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.