Probing the dynamical interaction of the para -sulfonato-calix[4]arene with an antifungal protein.

Calixarenes are hallmark molecules in supramolecular chemistry as hosts for small ligands. They have also conversely proved their interest as ligands toward assisted co-crystallization of proteins. These functionalized macrocycles target positively-charged residues, and notably surface-exposed lysines, with a site-selectivity finely characterized experimentally, but that remains to be assessed. Relying on a tailored molecular dynamics simulations protocol, we explore the association of -sulfonato-calix[4]arenes with an antifungal protein, as a small yet most competitive system with 13 surface-exposed lysines. Our computational approach probes the electrostatically-driven interaction, ruled out by a competition with salt bridges, corroborating the presence of two main binding sites probed by X-ray. The attach-pull-release (APR) method provides a very good assessment of the overall binding free energy measured experimentally (-6.42 ± 0.5 -5.45 kcal mol by isothermal titration calorimetry). This work also probes dynamic modifications upon ligand binding, and our computational protocol could be generalized to situate the supramolecular forces ruling out the calixarene-assisted co-crystallization of proteins.