File:GH3 2013 Fig3.png

            Figure 3.  Overlay of barley β-glucan exohydrolase isoenzyme ExoI with other known X-ray structures of multi-domain b-glucosidases.  While additional domains may be present (not shown for clarity), the core two-domain architecture observed for Exo1 and the unusual two-domain active site architecture (Asp nucleophile on domain 1 and general acid/base on domain 2) appears to be a structurally conserved feature of multidomain GH3 β-glucanases.  Colour coding: Exo1 domain 1 (magenta) and domain 2 (cyan) bound to Thiocellobiose (salmon) (PDB: 1IEX);  Pseudoalteromonas sp. Exo-1,3/1,4-b-glucanase ExoP (grey) (PDB: 3UTO); Thermotoga neapolitan β-glucosidase 3B  Bgl3B (orange) (PDB: 2X41); Kluyveromyces marxianus β-glucosidase KmBgl1 (yellow) (PDB: 3ACO); Hypocrea jecorina β-glucosidase Bgl1 (green) (PDB:3ZYZ);  Streptomyces venezuelae b-glucosidase DesR (blue) (PDB:  4I3G).