Characterization of the galectin-1 carbohydrate recognition domain in terms of solvent occupancy

Human galectin-1, a galactosil-terminal sugar binding soluble protein, is a potent multifunctional effector that participates in specific protein-carbohydrate and protein-protein interactions. Recent studies revealed that it plays a key role as a modulator of cellular differentiation and immunological response. In this work, we have investigated the solvation properties of the carbohydrate recognition domain of Gal-1 by means of molecular dynamics simulations. Water sites (ws) were identified in terms of radial and angular distribution functions, and properties such as water residence times, interaction energies, and free-energy contributions were evaluated for those sites. Our results allowed us to correlate the thermodynamic properties of the ws and their binding pattern with the N-acetilgalactoside ligand. These results let us further infer that the water molecules located at the ws, which exhibit much more favorable binding, are the ones replaced by -OH groups of the sugar.