To address this, this study compares the absolute binding free energies obtained using Boresch restraints and different implementations of multiple distance restraints for a single ligand (MIF-180) binding to a single protein (human macrophage migration inhibitory factor, or MIF). This was suggested as a good model system by Qian et al. because MIF is a pharmaceutically relevant protein, but of moderate size (342 residues), and no major conformational changes occur in the protein upon ligand binding (Figure ). In this work, the the standard binding free energy of MIF-180 was calculated using multiple sets of Boresch restraint parameters. The results were compared to those produced by non-rigorous implementations of multiple distance restraints similar to that of Mendoza-Martinez et al., and two rigorous multiple distance restraint schemes: one inspired by Salari et al., and one newly developed.