(a) Superposition of the crystal structures of StGE2 (shown in cyan), the S213A mutant (shown in dark blue), the S213A mutant in complex with MCU (shown in magenta) and the glycosylated (N-acetylglucosamine; NAG) Cip2_GE (shown in lime green; Pokkuluri et al., 2011). The catalytic triad residues are also indicated (the colour scheme follows the relevant structure). The three disulfide bonds that are formed in all structures are highlighted in yellow. (b) Expanded view of the active site indicating the ester bond hydrolyzed by StGE2. This figure was prepared with MolSoft (Raush et al., 2009).