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Knight, Benjamin

Physics

2011

MS

Myoglobin is a small heme-containing protein that reversibly binds diatomic ligands. The binding process serves as a model system for understanding the mechanism for biotechnological applications that include bioremediation, blood substitutes and signal transduction. A key component to understanding the ligand-binding reaction in myoglobin (Mb) and other heme proteins is a structural and electronic description ofthe transition state. Magnetic circular dichroism (MCD) arises from the Zeeman splitting of degenerate electron states ofthe heme iron. An externally-applied magnetic field can split energy levels so they preferentially absorb right-or left-circularly polarized light. Analysis of MCD spectra reveals changes in electron angular momentum at the active site. In this thesis proposal, I present preliminary MCD data on the rstates along the rebinding pathway for carbonbonoxymyoglobin. These data lay the groundwork for future investigations of themetastable photointermediate of MbCO and provide adirect electronic characterization of the ligand binding transition state.