A, reaction catalyzed by MshB. B, active site of MshB (Protein Data Bank entry 1Q74) containing a catalytic zinc ion. Only one of the four Zn2+-MshB monomers is shown. C, active site of MshB (Protein Data Bank entry 1Q7T) containing bound BOG. The structures of the two MshB-BOG monomers were overlaid, revealing two different locations for glucose binding to MshB, BOG1 and BOG2. The octyl chains of the active site BOG molecules are not observed in either monomer. GlcN-Ins, 1-d-myo-inosityl-2-amino-2-deoxy-α-d-glucopyranoside.