Shengjia Zhu

Advisor: Prof. Burgmayer

Research Partner: Alexandra Nagelski

Chemistry Department


Molybdeum Pyrrolopterin Dithiolene Complex: Modeling the Molybdenum cofactor


The conserved pterin dithiolene ligand that coordinates molybdenum cofactor at Molybdenumenzymes active site, called “molybdopterin”, is hypothesized to play a large role in enzymatic catalysis. As observed in protein crystal structures of several bacterial molybdoenzymes, molybdopterin can exist in both a tricyclic pyranopterin dithiolene form and as a bicyclic pterin-dithiolene form. Previous studies with different molybdopterin model complexes have indicated that the interconversion between the tricyclic and bicyclic forms via pyran scission and cyclization at C7 affects the electronic environment of the redox-rich molybdopterin. In this study, the essential functional group for ring-chain tautomerism, the hydroxyl group, is replaced by a methoxy group to potentially prevent ring cyclization in the new model complex (Et4N)[Tp*Mo(S)(S2mBMOPP)]. However, preliminary results from NMR showed methoxy group rearrangement to C7 and pryrrolo-ring formation at N5. Thus, investigating the driving force of methoxy group rearrangement and pyrrolo-ring formation has become of interest, due to the potential implications on further understanding of the pyran ring-chain tautomerism exhibited by molydopterin to understand its role in catalysis.