My research interests involve the use of EPR spectroscopy to determine the ligation of metals (primarily, copper) in proteins and complex biological systems. Current studies can be divided into two parts:
Collaborations with investigators interested in multifrequency EPR and metals.
More involved studies with cupric ion bound to proteins where much more time is spent obtaining EPR samples.
I use low-frequency EPR technology uniquely suited for prion research - the loop-gap resonator, which I started using in 1982 when it was developed by Drs. James S. Hyde and Wojciech Froncisz. I provide EPR analysis of the cupric sites in prions in collaboration with Glenn Millhauser, Professor at the University of California, Santa Cruz. These studies are aimed at identifying the molecular structure and function of the prion protein in its normal and abnormal states, a fundamental step toward developing treatments for prion diseases.
I mentored a graduate student, Hua (Julie) Yuan, and a visiting professor from the Universidade de Brasilia, Sebastiao Lemos, on a project studying EPR-detectable copper in particulate methane monooxygenase (pMMO). Interest in pMMO is high due to a detoxification reaction for trichloroethylene, a priority pollutant. Methanotrophic bacteria use methane as the sole source of carbon and energy. pMMO oxidizes methane to methanol. Presently, I am collaborating with Mary Lynn Perille Collins, University of Wisconsin-Milwaukee, Alan DiSpirito, Iowa State University, and students of Amy Rosenzweig, Northwestern University, on EPR-related projects. It is still to be determined whether pMMO has a new type of copper center.
Ongoing studies involve the detection of an iron-sulfur center in aconitase with William Walden, University of Illinois-Chicago; detection of the iron-sulfur center in Rieske protein (Toivo Kallas, University of Wisconsin-Oshkosh); detection of the tyrosyl radical in ribonucleotide reductase with several investigators; detection of metal complexes of known antitumor agents including bleomycin (David H. Petering, University of Wisconsin-Milwaukee); detection of the dimanganese site in gamma glutamylcysteine synthetase (Owen Griffith, Medical College of Wisconsin); and detection of chromium in the context of human lung toxicity (Charles Myers, Medical College of Wisconsin).