Quantitative Analysis of Various Metalloprotein Compositional Stoichiometries with Simultaneous PIXE and NRA

Faculty Mentor(s)

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

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Stoichiometric characterization has been carried out on multiple metalloproteins using a combination of Ion Beam Analysis methods and a newly modified preparation technique. Particle Induced X-ray emission (PIXE) spectroscopy is a non-destructive ion beam analysis technique well suited to determine the concentrations of heavy elements. Nuclear Reaction Analysis (NRA) is a similar technique which measures the areal density of a thin target by quantifying scattering cross sections of 3.4 MeV protons. A combination of NRA and PIXE has been developed to provide a quantitative technique for the determination of stoichiometric metal ion ratios in metalloproteins. About one third of all proteins are metalloproteins, and most do not have well determined stoichiometric compositions for the metals they contain. Current work focuses on establishing a standard method in which to prepare protein samples. A modified method of preparation is currently being investigated. The method involves placing drops of protein solutions on aluminized polyethylene terephthalate (Mylar®) and allowing them to dry. This technique has been tested for several proteins to determine cofactor content and has proven to be a reliable analysis method, accurately determining metal stoichiometry in these proteins.


This material is based upon work supported by the Hope College Dean for the Division of Natural and Applied Sciences and by the National Science Foundation under NSF-RUI Grant No.PHY- 0969058.

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