Drug–protein recognition processes investigated by NMR relaxation data: A study on corticosteroid–albumin interactions

In this paper we investigated the interaction processes occurring at the protein–solvent interface for prednisolone–albumin and prednisone–albumin systems, using an approach based on the analysis of proton selective relaxation rate enhancements of the ligand in the presence of the macromolecule. The contribution from the bound ligand fraction to the observed relaxation rate in relation to protein concentration allowed the calculation of the affinity index  [A]LT and the normalized affinity index  [AIN]LT which removes the effects of motional anisotropies and different proton densities, and isolates the contribution due to a decrease in the ligand dynamics caused by the binding with the protein. This approach allowed the comparison of the binding ability of prednisolone and prednisone towards albumin.