Sulfur K-edge XAS and DFT studies of Fe-S bonds in models and protein active sites: Effects of H-bonds on covalency and redox properties

COMP 112

Edward I. Solomon, edward.solomon@stanford.edu, Department of Chemistry, Stanford University, 333 Campus Drive, Stanford, CA 94305 and Abhishek Dey, Department of Chemistry, Stanford University, Stanford, CA 94305, Stanford, CA 94305.
Iron-sulfur proteins are involved in electron transport (e.g. Fe-S clusters), small molecule activation (e.g. P450, Nitrogenase) and other key biological processes. Knowledge of their electronic structure and, in particular, Fe-S bond covalency is crucial for understanding their function. Most of these sites have multiple hydrogen bonds to the sulfur ligands which play a major role in catalysis by tuning the electronic structures of these active sites. Sulfur K-edge X-ray Absorption Spectroscopy (XAS) been used to directly obtain the Fe-S covalencies of these active sites and their corresponding model complexes. DFT calculations on protein active sites and small model complexes reproduce the observed trend in the XAS data. These studies provide insight into the nature of these interactions and correlate weak H-bonding energies to the large changes in Fe-S covalencies which made dominant contributions to reactivity.
 

Bold Predictions in Theoretical Chemistry: A Poster Session in Honor of One of the Boldest, Bill Goddard, on the Occasion of his 70th Birthday
7:30 PM-9:30 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Computers in Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007