NMR spectroscopy and its biological applications; structure function relationships in proteins; stable-isotope- assisted multinuclear magnetic resonance spectroscopy; processing and analysis of multi-dimensional NMR data; structural genomics; metabolomics
central theme of our research is the application of nuclear magnetic
resonance (NMR) spectroscopy to the solution of biochemical problems.
The unique power of NMR lies in its ability to provide detailed
chemical and structural information at an atomic level about molecules
in solution--even when they are present in living cells or organisms.
The general strategy is to use multidimensional (2D, 3D, and 4D),
multinuclear magnetic resonance techniques to detect and assign
resonances from atoms of biological interest (e.g., 1H, 13C, 15N, and 31P).
With these assignments in hand, we can then interpret the wealth of
spectral information present in coupling constants, relaxation rates,
cross-relaxation rates, and chemical shifts. Proton-proton
cross-relaxation rates and a variety of measured coupling constants are
used to derive three-dimensional structures of these macromolecules.
Relaxation rates, line-shapes, and nuclear Overhauser effect
measurements provide information about molecular motions and
conformational changes. The kinds of information gained from such
investigations can be critical for learning how these molecules work
and how they can be redesigned to have desired properties. Our work
focuses on protein systems: Enzymes, electron transport proteins,
proteinase inhibitors, and nucleic acid binding proteins. We exploit
recombinant DNA technology as a means for producing the large amounts
of protein needed for NMR investigations and for introducing stable
isotopes of interest (most commonly 2H, 13C, and 15N).
Mutagenesis studies allow us to test hypotheses about the roles of
individual amino acid residues in determining properties such as local
structure, conformations and mobilities of side chains, hydrogen
exchange kinetics, rates of protein folding or unfolding, pKa values, oxidation-reduction potentials, and ligand binding.
students and postdoctoral fellows in the laboratory usually focus on a
particular biochemical system and use NMR as one of the tools for its
analysis. They are expected to become experienced in preparing samples
and in carrying out functional studies. Alternatively, they may focus
on developing instrumentation or novel ways of collecting or analyzing
ribbon diagram of brazzein indicating the positions of residues found
to be critical for the sweetness of the protein. Color code: red,
enhanced sweetness; light blue, moderately decreased sweetness; dark
blue, strongly decreased sweetness; dark gray, sweetness equivalent to
wild-type; light gray, residues not yet mutated (Assadi-Porter et al.,