Alex McPherson, Ph.D.
Hauptman-Woodward Institute
Principal Research Scientist

EDUCATION
B.A., Physics, Duke University
Ph.D., Biological Sciences, Purdue University

Research Interests

Research is being carried out in a number of different areas, all focused on the elucidation of macromolecular structure or larger assemblies of biological macromolecules. The principal techniques that are utilized are X-ray diffraction analysis of single crystals, and atomic force microscopy (AFM). The specific approaches and areas of interest are:

• The application of AFM to determining the structures of complex animal viruses. The strategy is to gradually degrade large virus particles chemically and enzymatically in a controlled manner, and visualize the products of the reactions using AFM. This is the classical dissection approach that has been used on larger organisms for two hundred years. The principal difference is that with AFM, macromolecular components, and how they are associated with one another, becomes directly observable. Ultimately, the objective is to elucidate not only the intricate architectures of the viruses, but the mechanisms by which they self assemble, decapsidate, and replicate. Currently the viruses on which we are focusing are Moloney mouse leukemic virus (MuLV), HIV, Mason – Pfizer monkey virus (M-PMV), vaccinia virus, mimivirus, adenovirus and several tailed bacteriophages.
  
  
• A primary focus of our research is the complete modeling, protein capsid plus encapsidated RNA, of a small T = 1 icosahedral plant virus, satellite tobacco mosaic virus (STMV). Currently, the virus, in which about 50% of the RNA can be visualized in electron density maps, has been refined to 1.45 angstrom resolution using X-ray diffraction data from frozen crystals. Efforts are now underway to increase the amount of RNA that can be placed in the model, to determine the secondary structure of the RNA, and to compose a model for the entire particle. This would represent the first instance where a complete virion structure has been determined.
  
  
• We have a long-standing interest in the structures of intact monoclonal antibodies, particularly those directed against tumors of various sorts. To date, the structures of three of the reported four intact antibody molecules studied by X-ray diffraction have been produced in this laboratory, as well as anti – idiotypic antibody derived Fab fragments of several. The IgG molecules have had as their targets antigens produced by melanomas, coleo-rectal carcinomas, and non-Hodgkin’s lymphomas. Efforts are continuing to crystallize and study additional members of this class of immunoglobulins.
  
  
• Enzymes, and some proteins of non-catalytic function, have been studied in this laboratory over a long period of time with the purpose of delineating the relationship between molecular structure and biological function. The enzymes have included a series of polysaccharide hydrolases such as pancreatic alpha amylase, chitinase, and xylanase. Also analyzed have been fungal lipase and penicillium protease, peanut peroxidase, the plant storage protein canavalin, ribonuclease, citrate synthase, and human met hemoglobin.
  
  
• We have had a longstanding interest in the technologies, chemicals, and procedures involved in the crystallization of proteins, nucleic acids, and viruses. Experiments are ongoing to discover new reagents that might advance progress in this area. The objective is significant to medical research and molecular biology because crystallization serves as the gateway to the application of X-ray diffraction analysis to biological structure, and biological structure is essential to understanding biological function. In addition, enzyme crystallization could provide entirely new approaches to the engineering of protein molecules and the rational design of new drugs for therapeutic and diagnostic applications.