The objectives of this research are to design new NMR experiments and computer software needed for refining the solution structures of small proteins and for determining the structures of proteins which are too large (10,000 - 25,000 MW) to be solved with existing methods. The work will expand upon recent advances in 1H-detection of 13C and 15N magnetic resonance applied to two-dimensional (2D-), 3D-, and 4D-NMR spectroscopy, triple-resonance assignments in proteins. New multidimensional- (MD-) NMR experiments will be designed which provide more precise NMR structural parameters than available with existing technology. In particular, we will design methods for accurate measurements of homonuclear and heteronuclear vicinal coupling constants in proteins. We will develop an approach for protein structure determination involving measurements of multiple vicinal couplings for each phi, psi, and chi1 dihedral angle in a small protein. These methods will provide better determination of local backbone and side chain conformation than is available with existing techniques. MD-NMR experiments will be designed which use PFG'S for suppression of H2O solvent signals in a single scan and for avoiding saturation transfer problems at neural pH. PFG's will also be used to overcome the dynamic range problems encountered in 1H-detected heteronuclear NMR of proteins at natural isotope abundance. This new technology will be applied for structural studies of growth factors involved in the molecular basis of cancer and wound healing, including proteins too large to study with existing methods. It will greatly enhance the applicability of NMR as a tool for rational drug design and protein engineering.
