Studies Toward the Rational Design of Ion Binding Proteins

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This award in the Inorganic, Bioinorganic and Organometallic Chemistry Program with a contribution from the Mathematics and Physical Sciences Office of Multidisciplinary Activities for instrumentation supports work in the laboratory of Professor James Cowan in the Department of Chemistry at Ohio State University. The research will examine and compare the Mg(II) binding domains of E.Coli RNase H, exonuclease II and other proteins. Since Mg(II) must be recruited from the environment or cellular medium and binding affinities are often not high, the stoichiometry of this metal cofactor required to effect hydrolysis is often not well defined. While the metal binding domains show considerable variation in charge density and coordination for the metal, they have comparable binding affinities. Studies will focus on calorimetric and NMR investigations of Mg binding to native and mutant enzymes. The results will form the basis for the rational design of proteins with novel cation or anion binding chemistry. This research involves a systematic investigation to define the relative importance of Mg(II) inner and outer-sphere coordination, metal ion charge density and solvation, binding affinity and other factors in the use of Mg(II) in important hydrolytic enzymes. Not only should these studies improve our understanding of the role of magnesium in proteins, but results should also prove highly significant in the rational design of ion binding sites in proteins.