Fig. 5. Structures of chaperone molecules bound in the GALC active site. X-ray crystal structures of (A) IGF, (B) IGL, (C) AGF and (D) DIL bound in the GALC active site. Compounds are colored as indicated. (Left panel) Unbiased difference electron density maps (F _O – F _C, 3.0σ, green) before ligand modelling at the active site of GALC. (Centre panel) Detail of the GALC active site with bound ligand, showing active site residues (sticks) and refined 2mF _O – DF _C electron density contoured at 0.25 e Å^–3 (blue). (Right panel) Schematic representation of hydrogen bond interactions (green dashed lines) between GALC and ligands.