Biodynamics: Vibrational Echo Correlation Spectroscopy

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Research is proposed to study dynamics and structure of biologically important systems including heme proteins, proteins with multiple metal centers, water in nanoscopic environments, and water-protein interactions in nanoscopic environments. Building on our current work and recent experimental and theoretical advances make possible the application of Vibrational Echo Correlation Spectroscopy, a powerful new approach to the study of these problems. Vibrational echo correlation spectroscopy with full phase information will be used to directly examine the structural degrees of freedom and dynamical interactions of biologically important systems in a manner that is akin to multidimensional NMR. The new research expands our currently successful application of multidimensional vibrational echo methods. Extending work on myoglobin-CO, mutants will be used to unravel structural dynamics throughout the protein. Experiments on hemoglobin-CO will relate the allosteric affect to protein dynamics at the active site and examine the temperature dependence of structural evolution. Cytochrome c mutant M80A, where the axial methionine residue is replaced with an alanine binds both CO and CN-, in the Fe+2 and Fe+3 oxidation states, respectively. This mutant will be studied to address fundamental dynamical differences that occur in the protein when the oxidation state of the heme group is changed. Proteins with multiple Cu centers will be studied. First, hemocyanin will be studied with CO bound at the active site, and insights into the active site protein dynamics gained from studies of hemocyanin will be applied to other binuclear copper proteins such as tyrosinase. The hemocyanin experiments are a precursor to the study of trinuclear Cu proteins such as laccase, ascorbic oxidase, and ceruloplasmin. Multiple azide anions will be bound to these electronically coupled Cu centers to study the dynamics and vibrational mode coupling between the azide ligands. Vibrational echo correlation spectroscopy provides a new type of analytical tool for the study of coupled metal centers that will also be applied to the several multiple metal centers in carbon monoxide dehydrogenasetacetyI-CoA synthase (CODH/ACS). Building on recent fundamentally new studies of water dynamics, the biologically important issue of the dynamics of water in nanoscopic environments will be studied. In addition, water-protein dynamical interactions and water-protein hydrogen bond dynamics in nanoscopic water environments will be examined.