Michael J. Maroney
Professor Emeritus of Chemistry, University of Massachusetts
Ph.D.: University of Washington Postdoctoral Training: Northwestern University; University of Minnesota
The focus of the research in my group is on the elucidation of the structure and function of transition metal ions in biological systems by use of a wide variety of biophysical measurements (principally spectroscopic techniques) and the synthetic model approach. From spectroscopic measurements such as x-ray absorption, electronic absorption, IR, Raman, epr, NMR and ENDOR, we can probe the structure of the metal center and the nature of the ligand environment. Synthetic models are used to interpret spectroscopic results. A recent interest has involved the biological function of Ni, which is now associated with five enzymes: hydrogenase, carbon monoxide dehydrogenase, methyl coenzyme M reductase, superoxide dismutase and urease. In the first three of these enzymes, Ni has been postulated to be a redox center. We have probed the redox role of the Ni center in Thiocapsa roseopersicina hydrogenase using x-ray absorption spectroscopic measurements on redox poised samples. These measurements fail to provide any support for a redox role for nickel, but do indicate that the Ni site is bound to the protein by S-donor ligands, some of which must be cysteinate ligands. Model studies point to the possible importance of the S-donor ligands in the chemistry associated with the Ni site.