Long-distance potentials: an approach to the multiple-minima problem in ligand-receptor interaction

The multiple-minima problem is a classical problem in molecular structure prediction. For ligand-receptor systems, a possible direction to alleviate this major obstacle is to simplify the objective function (intermolecular energy) and smooth its profile. We introduce long-distance atom-atom potentials for ligand-receptor interactions. The longer ranges result in averaging of the energy potential at a given point. Our simplified force field is based on a trivial empirical representation of interatomic interactions as a step function. We demonstrate that the intermolecular energy calculation by a systematic search with such a simplified long-distance force field delivers the global minimum (crystallographically determined position of the ligand) by radically suppressing local minima (or false-positive fits). The effectiveness of the approach is demonstrated on different molecular complexes of known structure.