Dr. Sharon Burgmayer
Metals are crucial for many biological reactions due to the fact that they are functionally versatile. Transition metals can be employed as biological catalysts, used as a means to transport molecules or ions, and function as the structural backbone of a compound. In order to better understand the complexity of transition metals and their complexes, model compounds are often used. Molybdenum is a transition metal that is present in many biological enzymes. Although there are many different molybdenum containing enzymes that function to control the redox activity of a variety of substrates, all molybdenum enzymes contain a molybdenum cofactor (Moco). The Burgmayer group has developed an innovative model for the Moco, which incorporates many of the vital structural elements that are present in all Mo enzymes. The Moco model is a molybdenum dithiolene complex is synthesized via the convergence of two synthetic pathways with the reaction of a molybdenum polysulfido compound with a pterinyl alkyne. The goal of this particular research was the synthesis of the molybdenum polysulfido compound and the alkyne reagents. The molybdenum polysulfido compound is also known as ‘tetrasulfide’. Tetrasulfide was synthesized effectively in two steps, in which Mo0 was oxidized to MoIV through the addition of sulfur to produce a tetrasulfide ligand. The pterinyl alkyne was synthesized effectively in seven steps. The first six steps created the pyrimidine and pyrazine rings that together are the pterin framework. In the seventh step an alkyne was combined with the pterin framework via a Sonogashira cross coupling reaction. Spectroscopic techniques such as H1 NMR, infrared spectroscopy and mass spectroscopy were all used to confirm the identities of the various compounds. The ability to effectively synthesize the compounds precedes the next step of constructing the Moco model. Through these reactions the Burgmayer group will be able to continue studying the reactivity and chemical nature of molybdenum enzymes, which hopefully will lead to a greater understanding about how the Moco enzyme functions within biological systems.