Absent inhibitor: the peptide inhibitor in the structure of phospholipase A2 (PDB entry 1jq8
; Chandra et al., 2002). The electron-density maps downloaded from the EDS show that the placed ligand overlaps with negative difference density below the −3σ level (a), while the omit maps do not support the presence of the ligand in the active site of the enzyme (b). (b) shows the 2.0 Å resolution mFo − DFc map contoured at ±3σ (green/red) and 2mFo − DFc maximum-likelihood omit map contoured at 1σ (blue). Maps were calculated for a refined model with the ligand atoms omitted.