Measuring ligand-protein binding using NMR diffusion experiments

Characterization of ligand-protein interactions is important because many biologically important processes are mediated by the binding of a small molecule to an enzyme or cell-surface receptor. Pulsed-field gradient nuclear magnetic resonance (PFG-NMR) spectroscopy measurements of diffusion coefficients permit noninvasive, quantitative analysis of binding over a broad range of dissociation constants and ligand:protein concentration ratios. An arsenal of specific and selective PFG-NMR methods has been developed by exploiting differential behaviors of small molecule ligands and macromolecular proteins. A discussion of several PFG-NMR methods and their relevant applications reveals the analytical value of using PFG-NMR diffusion measurements for studying ligand-protein binding, (C) 2004 Wiley Periodicals, Inc.