Investigation of the Molybdenum Cofactor through Chemical, Biochemical and Biophysical Studies

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Title: Investigation of the Molybdenum Cofactor through Chemical, Biochemical and Biophysical Studies. Molybdenum cofactor (Moco) is an essential biomolecule for life. Numerous enzymes rely on proper functioning of Moco and failure to biosynthesize Moco causes severe physiological distress and early childhood death. Outside the protein environment, this cofactor is unstable and has not yet been synthesized chemically. Moco has several redox active components and, together, these components can carry out up to ten-electron chemistry, while substrate transformation requires only two electrons. To understand how different components stabilize the electronic structure that supports reactivity, we will investigate discrete molecules with defined features. The work outlined in this proposal seeks to complete the first chemical synthesis of Moco. While in the reduced state Moco is unstable outside the protein environment, and how it is stabilized within a protein is not clear. The proposal also seeks to understand geometric properties of Moco in the DMSO reductase family of enzymes using periplasmic nitrate reductase (NapA) and its variants as a model through biochemical and biophysical studies. The specific aims of the proposal are: 1) to synthesize pterin Mo-centers and Mo=X (X=S,O) complexes allowing investigation of their geometric and electronic structures in relation to reactivity; 2) understanding the geometric and functional properties of the Mo-center in the DMSOR family using NapA as a model. Overall, new important molecular level knowledge will be generated about the structure-function for a class of enzymes important to human health.