Binding of dipeptides and tripeptides containing lysine or arginine by p-sulfonatocalixarenes in water: NMR and microcalorimetric studiesElectronic supplementary information (ESI) available: chemical shifts experienced by different protons of KK, RR, KKK or RRR in the presence of increasing amounts of 14 or 16; heat effects observed upon titration of 14, 16 or 18 by KK, RR, KKK or RRR; COSY

Abstract

The water soluble p-sulfonatocalix[n]arenes (n = 4, 6 and 8) (14, 16 and 18) show glycosylaminoglycan (GAG) mimicry, being both active antithrombotics and modulators of lysyloxidase activity. In order to understand how these synthetic receptors interact with GAG receptor sequences, we have undertaken a study to thermodynamically characterize the binding of dipeptides and tripeptides bearing lysine or arginine residues by 14, 16 and 18 in aqueous buffer at pH 8.0 and 298.15 K. The association constants, enthalpies and entropies of complexation have been determined using titration microcalorimetry. The structure of the complexes in solution has been studied by 1H NMR spectroscopy. Combining the microcalorimetric data, the binding shifts and the 2D experiments, the nature of the complexation may be clarified.