With this award, the Chemistry of Life Processes Program in the Division of Chemistry and the Molecular Biophysics Cluster in the Division of Molecular and Cellular Biosciences are jointly funding Professor James Allen and Dr. JoAnn Williams of Arizona State University to investigate the factors that give photosynthetic organisms the ability to convert light into chemical energy. The overall objective of this project is to engineer novel metal clusters that can catalyze light-induced oxidation reactions. A variety of experimental techniques are available in their laboratory and those of their collaborators to probe the activity of the novel metal clusters. The studies are directed at providing insight into the requirements needed for metal clusters to perform complex multi-electron reactions, including the production of molecular oxygen from water. The research of Professor Allen and Dr. Williams in using protein design to answer fundamental scientific questions about photosynthetic reactions and includes diverse participation in scientific research, including an important element of undergraduate exposure to modern research at the chemistry/biology interface.
In all photosynthetic systems, the primary energy transduction event is the light-induced generation of a charge-separated state in a pigment-protein complex. Detailed spectroscopic studies and three-dimensional structures of these complexes form a firm foundation for understanding many of their functions. However, the mechanism by which the manganese cluster of photosystem II catalyzes the essential biological process of water oxidation is a major outstanding question in the field. Thus this project is directed towards dissecting this capacity. The bacterial reaction center will serve as a platform to recreate features of the manganese cluster of photosystem II in a well-defined protein environment. Characterization of key properties of a variety of manganese clusters would reveal common motifs in metal clusters that facilitate oxidation reactions. Overall, the insight gained from these studies should help establish molecular concepts that explain how manganese cofactors in proteins efficiently perform intricate chemical reactions, as well as lead to the development of novel biological systems that are capable of accomplishing beneficial light-directed catalytic processes.
