Ligand-macromolecule complexes: affinity index determination by selective nuclear relaxation analysis

Proton NMR selective and non-selective spin-lattice relaxation rate measurements were used to monitor the strength of the overall complexation behaviour of a ligand (carbamazepine) toward a macromolecular receptor (albumin). The 'affinity index,' a quantitative parameter related to the strength of the ligand-macromolecule interaction, was determined from the experimental contribution of the bound ligand molar fraction to the observed selective spin-lattice relaxation rate. The effect of a second ligand (lamotrigine) on the carbamazepine-albumin interaction was also investigated and was found to have a modulation effect on the carbamazepine-albumin interaction. Copyright (C) 2001 John Wiley & Sons, Ltd.