Binding of dipeptides and tripeptides containing lysine or arginine by p-sulfonatocalixarenes in water: NMR and microcalorimetric studies

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.