Molybdenum enzymes are vital for various catalytic processes and are ubiquitous in nature, preforming oxygen atom transfer on a variety of substrates. At their active site there exists the molybdenum cofactor. Across nearly all forms of life, this molybdenum cofactor exists with minor changes in structure and function; despite these differences, each type of molybdenum cofactor contains one or two highly conserved pyranopterin dithiolene ligands. Although little is known about these ligands, without them the molybdenum cofactor is no longer catalytically active. Unfortunately, the molybdenum cofactor degrades quickly when it is removed from its protein matrix so it cannot be studied directly. The Burgmayer group focuses on the synthesis and analysis of various analogues for the Molybdenum cofactor with the ultimate goal of determining the role of the pyranopterin dithiolene ligandin catalysis.<br/>The general formula for our family of molybdenum cofactor models is [TEA][Tp*Mo(O)(S2C2(pterin)(R)], where TEA is tetraethylammonium, Tp* is tris(3,5-dimethylpyrazolyl)hydroborate, Mo exists in the Mo(IV) or Mo(V) oxidation state, and R is CH2OH which allows for solvent dependent cyclization to take place. This project aims to replace the R group with a single proton, increasing the overall planarity of the pyranopterin dithiolene ligand. Increasing the planarity of the model is proposed to have two main advantages. Firstly, planarity of this new model will more easily facilitate this full reduction. In addition, having a model that is conjugated without the pyran ring will increase our understanding of the electronics of our general analogue by allowing us to decouple the concept of the cyclization from the improved electronics of the conjugated system and study each in turn. In this poster we present results of the synthesis and chemical reactivity of this new synthetic model, and how it fits into our overall investigation of the behavior of the molybdopterin dithiolene ligand and how it contributes to catalysis.

Synthesis and studies of a new pterindithiolene model of the molybdenum cofactor

2019 Spring National Meeting

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