To further assess the quality of the employed structural data, we calculated the molecular electron density score for individual atoms (EDIAm) for each ligand We previously found that a ligand EDIAm value of 0.4 is sufficient to yield reasonable reference structures for docking. Calculation of the EDIAm value failed for a number of cases due to a lack of experimental data and mistreatment of crystal symmetry: CSKDE95 (11 cases), CS244 (14 cases), CS405 (76 cases), and SARS-MP-76 (45 cases). For 44 cases of the SARS-MP-76 set, the authors attributed a degree of confidence to the quality of corresponding structure (Table ), which we used instead of the EDIAm value when it was not available. We also assessed for all structures if the ligand of interest forms non-bonded interactions with a symmetry-related copy of the complex, which would be present in the experimental structure but absent in the docking calculations. To this end, we used the Crystal Contacts tool of UCSF Chimera 72 with a cutoff length of 4.5 Å. Additionally, the portion of buried surface area of the ligands was calculated with CHARMM, 73 using a probe radius of 1.4 Å. The results of this analysis are shown in the Supporting Information (Tables , S4, S5).