Fig. 3

Recombinant HvExoI and with perfused Glc, G6SG-OMe, or G2SG-OMe. a Stereo view of recombinant HvExoI in a ligand-free form. Two glycerol molecules (carbons: green sticks) (Gol 1 at occupancy 0.5; Gol 2 in three alternate conformations) are bound in the −1 and +1 subsites. b Stereo view of recombinant HvExoI with two Glc molecules in the ⁴C₁ conformation (carbons: yellow sticks) at 0.8 occupancy and in the ¹S₃ conformation (carbons: cyan sticks) at 0.2 occupancy, bound in the −1 and +1 subsites. c Stereo view of recombinant HvExoI with G6SG-OMe (carbons: orange sticks) at 1.0 occupancy, bound across the −1 and +1. d Stereo view of recombinant HvExoI with G2SG-OMe (carbons: orange sticks) at 0.7 occupancy, bound across the +1 and putative +2 subsites. Water molecules are shown as red spheres. Separations of less than 3.50 Å from the active site residues (carbons: grey sticks) are shown as dashed lines. Derived |2mF_obs − DF_calc| electron density maps are contoured at 1σ for G2SG-OMe and Gol (blue mesh) in (a–c). In (d), electron density maps are contoured at 1σ for PEG (orange mesh) and Gol (green mesh) in the −1 subsite