Associate Professor of Chemistry, University of Massachusetts
Ph.D.: University of California, San Diego
Understanding the fundamental chemistry of biological processes, from reactive intermediates to complex recognition events is the focus of my research. Students will have the opportunity to employ a wide range of biochemical and chemical techniques, from enzyme mutagenesis, purification, and kinetics, to the synthesis of coordination compounds, to spectroscopy. Three areas of research will be pursued.
The first area is directed to understand biological strategies for C-H activation, as found in a variety of enzymes and in DNA modifying reagents. These reactions often proceed by an Ho (H+ and e-) transfer that shows evidence of hydrogen tunneling, calling into question conventional reaction theories. Researchers will characterize the nature of Ho transfer in both enzymes and in model complexes - do atomic motions promote such reactions? Is the reaction concerted (Ho) or stepwise (H+ + e-)? Some initial targets for study: CuII-phenoxylo species, as found in galactose oxidase; Iron-oxo/hydroxo dimers, as found in methane monooxygenase; and bimetallic RuII-MIII species. This research will address fundamental questions about catalysis, including the role of nuclear tunneling and atomic motion along the reaction coordinate.
The second area is non-heme Fe enzymology and oxidation chemistry. Mononuclear FeII enzymes utilize O2 to hydroxylate bio-molecules, and are important for basic metabolism and antibiotic synthesis. Students will use kinetics and spectroscopy to characterize the reactivity of metal centers in proteins. The initial goal of this research is to identify the reactive oxidant in these enzymes ([FeIV=O]2+ ?), with future goals being the control of this chemistry for improved antibiotic synthesis.
The third area of research is biomimetic self-assembly of nanoclusters. This builds on nature's ability to organize large structures by using complex protein recognition elements. Students will integrate biochemical protein selection techniques with chemical strategies to explore these mineral-binding motifs. Initial efforts will be directed at characterizing the structure of each mineral-protein recognition site. Future goals are to use multiple binding interaction for the self-assembly of optical and magnetic materials.
Knapp, M. J. ; Klinman, J. P. "Kinetic studies of oxygen reactivity in soybean lipoxygenase-1," Biochemistry 2003, in press.
Knapp, M. J. ; Rickert, K.; Klinman, J. P. "Temperature-dependent isotope effects in soybean lipoxygenase-1: Correlating hydrogen tunneling with protein dynamics," J. Am. Chem. Soc. 2002, 124 , 3865-3874.
Knapp, M. J. ; Seebeck, F. P.; Klinman, J. P. "Steric control of oxygenation regiochemistry in soybean lipoxygenase-1," J. Am. Chem. Soc. 2001, 123 , 2931-2932.
Knapp, M. J. ; Krzystek, J.; Brunel, L. C.; Hendrickson, D. N. "High-frequency EPR study of the ferrous ion in the reduced rubredoxin model [Fe(SPh)4]2-," Inorg. Chem. 2000, 39 , 281-288.
Aromi, G.; Knapp, M. J. ; Claude, J. P.; Huffman, J. C.; Hendrickson, D. N.; Christou, G. "High-spin molecules: Hexanuclear Mn-III clusters with [Mn6O4X4]6+ (X = Cl-, Br-) face-capped octahedral cores and S=12 ground states," J. Am. Chem. Soc. 1999, 121 , 5489-5499.