This project is aimed at understanding the principles underlying the mechanisms of light energy conversion in the photosynthetic reaction center protein from bacteria. The principal cofactor of interest is the quinone of the protein's two sites of oxidation- reduction catalysis (QA and QB). Quinone chemistry is at an advanced stage of understanding and many structures are at hand. The reaction center is well-characterized, the quinones can be reversibly removed and site-directed mutants can be generated. Dr. Dutton plans to measure the binding affinities of a wide variety of quinones for the QA site, compare in vitro and in situ electrochemical properties, make structural determinations on quinone-replaced reaction centers using electron paramagnetic resonance and X-ray diffraction and measure electron transfer events and kinetics. It is now well-established that in photosynthesis the reaction center protein accepts light energy and initiates a series of intra-protein electron transfer steps that are directed vectorially across the supporting cytoplasmic membrane. The reaction center cofactors contained within three subunits of the reaction center include four bacteriochlorophylls, two bacteriopheophytins, two quinones and an iron atom.***//
