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., 2000).

The 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.