Funnel metadynamics as accurate binding free-energy method

Abstract

A detailed description of the events ruling ligand/protein interaction and an accurate estimation of the drug affinity to its target is of great help in speeding drug discovery strategies. We have developed a metadynamics-based approach, named funnel metady-namics, that allows the ligandtoenhance the samplingof the target binding sites and its solvated states. This method leads to an efficient characterization of the binding free-energy surface and an accurate calculation of the absolute protein-ligand binding free energy. We illustrate our protocol in two systems, benzamidine/ trypsin and SC-558/cyclooxygenase 2. In both cases, the X-ray conformation has been found as the lowest free-energy pose, and the computed protein-ligand binding free energy in good agreement with experiments. Furthermore, funnel metadynamics unveils important information about the binding process, suchasthe presence of alternative binding modes and the role of waters. The results achieved at an affordable computational cost make funnel meta-dynamics a valuable method for drug discovery and for dealing with a variety of problems in chemistry, physics, and material science.