Fig. 4

Substrate binding sites of AaGal, IaGal and BlGal. Substrate subsites at the non-reducing end increase incrementally from fungal enzymes (AaGal PDB ID 6Q3R) to archaeal enzymes (IaGal PDB ID 7OSK) to the bacterial BlGal enzyme (PDB ID 1UR0). The galactobiose and galactotriose ligands are shown as white sticks in the AaGal and BlGal structures, respectively. The same ligands are shown as white lines after superposition onto the IaGal structure