Absent ligand. The ascorbic acid molecule as placed in the structure of hyalouronate lyase from S. pyogenes, PDB entry 3eka
(Mishra et al., 2009), is unsubstantiated by the difference omit map. The 3.1 Å resolution mFo − DFc map contoured at ±3σ (green/red) and 2mFo − DFc maximum-likelihood omit map contoured at 1σ (blue) are shown. Maps were calculated for a refined model with the ligand atoms omitted.