In this project jointly funded by Experimental Physical Chemistry and Molecular and Cellular Biosciences, Keith Hodgson of Stanford University will use x-ray absorption spectroscopies to investigate the structure and function of metal ion sites in chemical and biological systems. Studies include the effect of metal oxidation state on structure and reactivity in proteins such as quinol oxidase, the mechanism of ligand binding in nitrogenase, the structural characterization of intermediates in the methane monooxygenase enzyme reaction cycle, and the elucidation of the structures of inorganic cluster complexes and bridged metal assemblies. Theoretical treatments to extend multiple scattering analysis for chemical systems will also be developed and applied to these systems. Metal sites play a key role in the specific function of biological molecules. Iron, an important component of hemoglobin, is also present in nitrogenase, the molecule which converts atmospheric nitrogen to ammonia, one of nature's fertilizers. This research will determine the structures, reactivities, and bonding of metal sites in a variety of biologically important systems. This information will be valuable in the effort to produce enzymes with chemical characteristics suited to particular needs such as the environmentally benign production of fertilizer.
