My research is focused on the study of the active centers of metalloproteins using Electron Paramagnetic Resonance (EPR) and related spectroscopic techniques. Metalloproteins are important biological species with vital functions in many living systems, such as oxygen transport and storage in humans, photosynthesis in plants, and nitrogen fixation in bacteria. EPR is particularly suited for this kind of research since it can single out the paramagnetic species at the active site of a metalloprotein and tell us what it is, its valence state, its spin state and how it interacts with the surrounding ligands and with other ions. With this information, the structure of the active site can be determined, enabling us to understand how the protein works.

One of our major projects is the development of a rare earth crystalline thermometer for frozen EPR metalloprotein samples. The need for such a thermometer arose from the fact that precise knowledge of the temperature of such samples studied in commercially available EPR spectrometers is not possible. This is due to the inherent limitations of the liquid helium continuous-flow cryostats employed. Single crystals of cerium trifluoromethane sulfonate can be incorporated within protein samples and give us accurate information on the temperature of the protein sample. We are attempting to grow such crystals, characterize them and find ways of incorporating them within the protein samples.

Other projects currently underway are: EPR measurements of the enzyme Cytochrome c554, a protein with a new type of a tetra-heme cluster that has important functions in metabolic pathways (collaboration with the Hendrich group, Department of Chemistry, Carnegie Mellon University); Improvement of the performance of the modulation coils for the CMU Q-band (34 GHz) EPR spectrometer; Investigation of unknown metalloproteins in collaboration with Structural Proteomics at the University of Toronto; Development of an electron-nuclear double resonance (ENDOR) accessory for the Q-band spectrometer at Carnegie Mellon University; EPR studies of color centers in mineral single crystals (collaboration with the Carnegie Mellon Research Institute).