Mechanisms of Cofactor Action in Enzymatic Reactions
Enzymes carry out biochemical reactions with astronomical rate enhancements and amazing stereoselectivities, mediating the huge quantity and variety of cellular transformations that constitute what is vaguely termed “life.” Our laboratory is endeavoring to understand at the detailed molecular level the reaction mechanisms employed by various enzymes, and then to exploit what we learn to impact favorably on human health and the human condition in general. A particular focus is to understand the manner in which enzymes bind and use cofactors—whether simple metal ions, complex metal clusters, or small molecules—to increase their catalytic capabilities beyond that which is supported by the functional groups of the twenty naturally occurring amino acids. To characterize enzymes and interrogate their modes of action, we use traditional biochemical and enzymological approaches in combination with structural methods such as X-ray crystallography and various forms of spectroscopy, as well as small-scale organic synthesis and fast-reaction kinetic methods. A growing interest in our lab has been to understand the mechanisms of enzymes that catalyze posttranslational modification of proteins by catalysis that proceeds through organic radical intermediates. Particular focus is on enzymes that use iron-sulfur clusters and/or S-adenosylmethionine in catalysis.