Absent ligands. Four protein–ligand complex structures presented in Mir et al. (2009) include ligands that are not supported by electron density. All panels show the omit maps for complex structures with the following ligands: (a) indomethacin (PDB entry 3ib1
), (b) diclofenac (PDB entry 3ib0
), (c) aspirin (PDB entry 3iaz
) and (d) α-methyl-4-(2-methylpropyl)benzeneacetic acid (PDB entry 3ib2
). The 2.2 Å (a), 1.4 Å (b), 2.0 Å (c) and 2.29 Å (d) resolution mFo − DFc maps contoured at ±3σ (green/red) and 2mFo − DFc maximum-likelihood omit maps contoured at 1σ (blue) are shown. Maps were calculated for a refined model with the ligand atoms omitted.