NMR diffusion and relaxation study on ibuprofen - HSA interaction

NMR diffusion and relaxation measurements were applied to study the ibuprof en-protein interaction by changing the drug concentration in solutions cont aining 0.1 M human serum albumin (HSA). On the basis of the assumption that the drug molecules undergo fast exchange between the binding and free stat es, the association constant, K-a, for drug-HSA complexes is found to he ab out 60, and the number of binding sites, n, is about 50. The small associat ion constant and the big binding site number suggest weak interactions betw een ibuprofen and HAS.