Synthesis and Characterization of Pterin-Based Molybdenum Cofactor

Posted July 28th, 2011 at 9:26 pm.

Abstract: Suyin Lee
Mentor: Dr. Sharon Burgmayer

Molybdenum is an essential transition element that forms a catalytic center of enzymes such as nitrogenase, nitrate reductases, sulfite oxidase and xanthine oxidoreductases. Some of these enzymes play important roles in carbon, nitrogen and sulfur cycles in the ecosystem while others are essential for proper human neurological development.  Two different systems have been found to control redox and catalytic functions of molybdenum which serves as an efficient catalyst in oxygen-transfer reactions. However the cofactor is both oxygen sensitive and very unstable independent of an enzyme.

Over 50 different pterin-containing molybdenum enzymes are known and classified on the basis of the coordination chemistry of molybdenum in their active site. The core structure of a pterin-based molybdenum cofactor consists of a 6 carbon substituted pyrano ring, a terminal phosphate and a unique dithiolate group coordinating to a molybdenum atom.  The Burgmayer group developed a successful pathway to synthesize and characterize Mo complexes particularly containing the pterinyl-dithiolene ligand where molybdenum is in both Mo(4+) and Mo(5+) oxidation states.  A coupling reaction of a molybdenum tetrasulfide reagent, TEA[Tp*MoIV(S)S4]with pterinyl alkynes directly produces the chelated pterin-dithiolene ligands described above.
The objective of this research is to synthesize molybdopterin and its precursors tetrasulfide and a dimethylated pterinyl alkyne, TEA[Tp*MoIV(S)S4] and BMOPP respectively. With successful and efficient experimental methodologies previously conducted by the Burmayer lab, this research focuses on the development of a highly efficient larger-scaled production of pure molybdenum tetrasulfide and BMOPP reagents. Characterization methods commonly used in this research include electrospray ionization mass spectrometry, infrared spectroscopy and NMR.

Filed under: 2011,Burgmayer, Dr. Sharon,Lee, Suyin by Michelle Han

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