Mossbauer studies of iron containing enzyme active sites and model complexes

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This award in the Chemistry of Life Processes (CLP) program, co-funded with the Division of Molecular and Cellular Biosciences (MCB), supports work by Professor Codrina V. Popescu at Ursinus College, an undergraduate liberal arts institution. The proposed Mössbauer investigations include studies of iron complexes and the exploration of novel iron sites in proteins. Mössbauer spectroscopy provides insight into the electronic structure and bonding situation of iron compounds by probing the iron nucleus. Iron is the most abundant transition metal found in biological systems, being involved in a variety of physiological processes carried out by enzymes and transport proteins. Thus, to understand biological processes at a molecular level, one must elucidate the electronic structure of iron coordination complexes. The study of metalloproteins has seen a great development due to the enticing prospect of using design elements inspired by Nature in manmade catalysts for cleaning out pollutants through catalytic oxidation, or cheaply obtaining hydrogen to be used as a fuel. This fundamental research seeks to accomplish two types of results. First, large families of iron compounds could be systematically characterized, a broad study useful in establishing correlations between structural and spectroscopic changes in these molecules. A second, more challenging endeavor, is the resolution of spectroscopic problems by analyzing a set of spectra for a single compound under carefully chosen conditions. A picture of the electronic structure of a given compound can then be generated from the spectral parameters. The long-term goals of this research are the elucidation of structure and mechanism of hydrogenases and certain oxygenases, which have direct applications in fuel and pollution control technologies. For example, the enzymes hydrogenases catalyze the production and breakdown of molecular hydrogen. If understood well, these enzymes may offer a cheaper, non-polluting way, to obtain hydrogen fuel. This type of research has a significant impact in the chemical and biological sciences, given that it provides answers to fundamental structural questions, such as structure and bonding, and uncovers their profound implications on the function of the active sites in question.In terms of broader impacts, the proposed research supports a close mentor-student relationship, in which students are part of the scientific pursuit from hypothesis generation to interpretation of results. The expected impacts on undergraduate training and education include: (1) to develop and maintain an undergraduate research program that fosters student growth and independence through cultivation of logic and problem-solving skills; (2) to provide students with interdisciplinary projects that promote learning spectroscopy hands-on while solving current scientific problems; (3) to provide the resources for external presentations and publications.