NMR spectroscopic diffusion, chemical shift and linewidth measurements of low-affinity binding of ibuprofen enantiomers to human serum albumin

The binding of racemic, (R)(-) and (S)(+)-ibuprofen (IBP) to human serum al bumin (HSA) was studied using NMR spectroscopy. Having saturated the tight binding sites, the extent of weak binding was then investigated. The molecu lar diffusion coefficients of IBP in HSA solution at different concentratio n ratios indicate that there is no significant difference in binding capaci ty of the two enantiomers of IBP to HSA at high IBP:HSA ratios. However, th ere are chemical shift and linewidth changes in the (NMR)-N-1 spectrum of I BP in the presence of HSA induced by the binding and this suggests that the major binding interaction involves the sec-butyl chain of the IBP molecule binding to HSA in hydrophobic pockets. Copyright (C) 1999 John Wiley & Son s, Ltd.