XAS ELECTRONIC AND GEOMETRIC STRUCTURAL STUDIES OF COPPER REDOX CENTERS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We propose to extend our previous studies on plastocyanin, using a combination of S K-, Cu L-, and Cu K-edge and EXAFS spectroscopies, to define the electronic and geometric structure of Cu-containing electron transfer proteins. The first part of our studies will focus on the understanding the differences between classic blue Cu sites and perturbed blue copper sites. A series of native and mutant proteins, where the axial ligand is systematically varied, will provide insight into the role of the axial ligand and other factors that control redox activity in blue copper sites. The second part of our studies will focus on the CuA center of cytochrome c oxidase and nitrous oxide reductase. We are interested in determining the nature of the ground state wave function in Cu A, defining contributions to the delocalization of the site, and gaining insight into ligand field contributions to metal-metal bond formation. This will be achieved through isotropic studies at the Cu K-, S K-, and Cu L-edge, as well as through polarized Cu K- and S K-edge studies.