Exchange-transferred NOE spectroscopy and bound ligand structure determination

The exchange-transferred nuclear Overhauser effect of NMR spectroscopy provides information on small-molecule ligands in association with high-molecular-weight proteins or nucleic acids, or with biomolecular assemblies such as membranes. The method has proved particularly useful for the structural analysis of proton-rich, flexible ligands and for screening mixtures of ligands for binding activity. Recent analysis has established the accuracy of bound peptide structures determined from transferred nuclear Overhauser effect data and that intermolecular spin diffusion effects do not diminish the reliability of the structural result. New applications of the method involve systems of greater complexity, such as membrane-bound receptors and ribosomes. In addition, new experiments have been developed that exploit the transfer of other types of NMR signal (saturation, cross-correlation, dipolar coupling) to obtain structural information.