Ion Beam Analysis of Metalloprotein Stoichiometry

Faculty Mentor(s)

Dr. Paul DeYoung, Hope College
Dr. Graham Peaslee, Hope College

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This material is based upon work supported by the Howard Hughes Medical Institute and by the National Science Foundation under NSF-PHY Grant No. 0969058.


Particle induced X-ray emission (PIXE) spectroscopy is a non-destructive ion beam analysis technique well suited to determine the concentrations of heavy elements. Particle elastic scattering analysis (PESA) is a similar technique which measures the areal density of a thin target by quantifying the energy loss of the transmitted ions. A combination of PESA and PIXE has been developed to provide a quantitative technique for the determination of stoichiometric metal ion ratios in metalloproteins. About a third of all proteins are metalloproteins, and most do not have known stoichiometric compositions for the metals they contain. Current work focuses on establishing a standard method in which to prepare protein samples. Two methods of preparation are currently being investigated. The first involves spotting protein solutions on aluminized polyethylene terephthalate and allowing them to dry. The second uses the process of native polyacrylamide gel electrophoresis in order to separate proteins and then drying them to provide adequately thin samples. These methods are compared for several proteins to determine their respective effectiveness and to develop a standard model for running ion beam analysis of metalloproteins.

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