Structure and dynamics of β-lactoglobulin in complex with dodecyl sulfate and laurate: a molecular dynamics study

Bovine β-lactoglobulin (βlg) is able to recognize a wide variety of hydrophobic ligands. Although binding promiscuity is characteristic of highly hydrophobic interactions, the structural plasticity of the βlg binding cavity entrance seems to be crucial for the interaction with polar moieties of different ligands. On the other hand, thermodynamic studies have shown that βlg can associate to cognate ligands with distinctly different binding energetics, as in the case of the closely related molecules lauric acid (LA) and dodecyl sulfate (DS). In the recognition of LA, βlg shows a classical hydrophobic signature (entropically driven), whereas the interaction of βlg with DS exhibits a nonclassical hydrophobic signature (enthalpically driven). To gain insights into these opposed binding behaviors, MD simulations were carried out on βlg in apo-form and bound to DS or LA. Overall, the results suggested that the distinct energetic signatures of these ligands come from distinct optimizations of both hydrophilic and hydrophobic contacts with the protein.