Date of Award


Degree Type




First Advisor

Bayachou, Mekki

Subject Headings

Electrochemistry, Ionic solutions, Heme, Hemoproteins, Nitric-oxide synthase, Electrochemistry, Hemeproteins, Nitric oxide synthase, NOS, Myoglobin, Proton transfer, Ionic liquids, Isotopic effects


We investigate the changing behaviors of myoglobin and nitric oxide synthase (NOS) in the near-absence of bulk water and/or protons by using ionic liquid butyl methyl imidazolium tetrafluoroborate as a non-aqueous milieu. Through direct charge transfer and metalloprotein-mediated catalytic reduction of oxygen and nitric oxide, we shed light on diverging aspects on how the two hemeproteins face the scarcity of water and/or protons in bulk. Isotopic effect investigations using D2O further elucidates kinetic aspects of proton transfer. Finally, in the case of NOS oxygenase, pterin cofactor binding and NOS-mediated catalytic oxidation of L-arginine in ionic liquids interrogates proton and water availability as a modulating factor affecting electrochemically-driven production of nitric oxide. Overall, our results indicate that the catalytic and redox properties of NOS and other heme-proteins change in a unique way as a function of available water. The redox and catalytic behavior of each metalloprotein is rationalized in terms of its inherent structural aspects

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