RUI: Magnetic circular dichroism of dicobalt(II) enzymes

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Through this award, the Chemistry of Life Processes Program is funding Professor James Larrabee at Middlebury College to carry out studies of metallohydrolases using magnetic circular dichroism (MCD) spectroscopy. The five metallohydrolases that will be studied are related to health and medical problems of current importance for the society. The active sites of these enzymes are chemically similar; specifically they include two metal ions bridged by carboxylate and water (or hydroxide) ligands. The enzymes are studied by the research group of Professor Larrabee in the Co(II) form, which provides an especially strong MCD signal. One aim of the research is to improve our understanding of how substrates interact with the metal ions in the active sites. Changes in the metal environment caused by the binding of substrate analogues that function as inhibitors to the enzymes are monitored by MCD spectroscopy and provide insight into the mechanism of the enzyme. A second aim is to discover which amino acid residues in the active site are important for the function of these enzymes. Understanding how enzymes function is of scientific interest and, in the case of enzymes implicated in disease-related biological processes, it may help with the diagnosis and treatment of the diseases. The enzymes studied by Professor Larrabee pertain to the latter category and the proposed studies are designed to advance the understanding of their mechanism. The spectroscopic and calorimetric studies described in the proposal will examine the metal binding and the electronic structure of the active sites of the enzymes. Changes in the active sites induced by interaction with substrate or substrate analogs that function as inhibitors will also be studied. The proposed research is conducted at Middlebury College by undergraduate students. Research experiences such as those undertaken by the Middlebury undergraduates are known to encourage the students to further their science education and to pursue careers in science.