Evaluation Metrics

The enrichment factor (EF) measures the enrichment of actual ligands in a docked hit-list given a specific percentage of the dataset (threshold). The EF is defined as the ratio between actual number ligands (hits) found at the top x% of the screened database (Hits_x%) and the number of molecules at that threshold N_x%, normalized by the ratio between the total number of actual ligands within the entire dataset (Hits_total) and the total number of molecules of the latter (N_total).

Thus, the EF represents the probability of finding an actual ligand within the x% of the screened database with respect to the probability of finding an actual ligand at random. Whenever a molecule is represented within a chemical library with different states according to its protonation or chirality, each state is assigned an individual score, and the lowest score is used in the hit-list, and thus to calculate the EF. Throughout this work we report EF(1) and EF(2), since they are more representative of early enrichment.

We also report receiver operating characteristics (ROC) curves for each of the studied systems, measuring the area under the curve (AUC).