Biophysical and Model Studies of NiSOD

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Nickel-containing superoxide dismutases (NiSODs) represent a completely novel mechanism for the elimination of superoxide in biological systems. The proposed project uses an interdisciplinary approach to explore the structure and function of NiSODs found in Streptomyces species, an organism that is responsible for many of the antibiotics currently available to medicine. Single crystal x-ray diffraction, x-ray absorption spectroscopy, vibrational spectroscopy and mass spectrometry will be used to examine structural aspects of NiSOD. These techniques will characterize the overall structure of the protein, determine the structure of the metal site and the dioxygen species present in various forms of the enzyme (including potential reaction intermediates or inhibitor complexes), and help to elucidate the role of quaternary structure in the function of the enzyme. Site-directed mutagenesis techniques and kinetic measurements will be used to test the role of specific amino acid residues in the structure of the catalytic site, with the effect of mutation monitored by measurement of the catalytic rate constant. Kinetic methods will also be used to examine the role of quaternary structure and an unusual product inhibition that is associated with peroxide in NiSOD.Broader Impact: The proposed research also provides a significant training opportunity for students at all levels (undergraduate through post-doctoral) at the interface of biochemistry and inorganic chemistry. Students will benefit from the association with a Chemistry-Biology Interface training program on campus, collaborations with scientists at other institutions in the U.S, and from a NSF-funded exchange program with a laboratory in Hungary. Students will be exposed to a number of techniques and concepts from both biochemistry and inorganic chemistry. Students will be drawn from a diverse pool, and effort will be made to provide opportunities for minorities.This project is funded jointly by Molecular Biochemistry and Inorganic, Bioinorganic & Organometallic Chemistry Program.