The Molybdenum Cofactor: Modeling the Swiss Army Knife of Metabolic Diversity
The pterin-dithiolene ligand (MPT), uniquely found in mononuclear molybdenum (Mo) and tungsten (W) enzymes, continues to intrigue us. The complexity of this ligand has been suggested as a cog in Mo and W enzyme function, and the pterin has been increasingly appreciated for its electronic contributions. To elucidate the conundrum of pterin dithiolene function, this dissertation has synthesized seven model complexes designed to explore questions pertinent to Mo cofactor (Moco) enzymes. Structural and electronic differences between quinoxaline and pterin based models and how those differences affect reactivity studies are discussed, pterin reduction on models with, and without, the ability to form a pyran ring are described, physical parameters pertinent to pyran cyclization are analyzed, and a methanol variation of covalent hydration is observed. Together, each set of results experimentally provides evidence for MPT participation, modulated by the protein, in catalysis.
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