Hope College Physics Department
Research Experiences for Undergraduates
Summer 2011
Project Summary


Project Title: Quantitative Analysis of Various Metalloprotein Compositional Stoichiometries with Simultaneous PIXE and NRA
Student Name: Andrew McCubbin
Student's Home Institution: Hope College
Research Advisor: Dr. Paul DeYoung and Dr. Graham Peaslee
Source of Support:

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.

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 deter¬mine 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 metallopro¬teins. About one third of all proteins are metalloproteins, and most do not have well determined stoichiometric compositions for the met¬als 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.
Publications and Presentations:
“Ion Beam Analysis of Metalloprotein Stoichiometry”, Andrew McCubbin. 2011 Celebration of Undergraduate Research, Hope College, April 15, 2011.