Ligand superpositions prediction made easy. FlexS is a computer software for predicting ligand superpositions. For a given pair of ligands, FlexS predicts the conformation and orientation of one of the ligands relative to the other one. In FlexS the reference-ligand is assumed to be rigid, thus, it should be given in a conformation which is similar to the bound state.

The superposition algorithm in FlexS requires only little manual intervention. Nevertheless, in some cases additional information about the ligands or even the superposition is known. You can integrate this knowledge into the computations with FlexS by carrying out single steps manually. Thus, FlexS is designed for interactive work on ligand pairs as well as for ligand-based virtual screening.

FlexS Features:
1. FlexS is fast. On our ligand-ligand benchmark set of about 280 molecule pairs, FlexS takes less than 2 minutes per superpositioning prediction on the average. The computing time depends on the size of the ligands, and the degree of ligand symmetry and flexibility and lies in the range from a few seconds up to a few minutes.
2. The conformational flexibility of the ligand is taken into account by considering both torsion angle flexibility as well as the conformational flexibility of ring systems. In the current version of FlexS, the reference-ligand is rigid.
3. The placement algorithm in FlexS is based on aligning interacting groups common between the molecules. This ensures that the search is limited to low-energy structures improving the quality of the results in a given amount of computing time.
4. FlexS is based on sophisticated physico-chemical models. The MIMUMBA torsion angle database is used for the creation of conformers, an interaction geometry database is used to exactly describe intermolecular interaction patterns. For scoring, the Boehm function (with minor adaptions necessary for docking) is applied.

The license of this software is Freeware, you can free download and free use this calculator software.