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Figure 2
Comparison of the EGPfΔN30 structure at pH 5.5 and at pH 9.0 identified by colour: red, pH 5.5; blue, pH 9.0. (a) Wall-eyed stereoview of the overall crystal structure of EGPfΔN30 drawn as a ribbon model viewed from the front. The two EGPfΔN30 structures are superimposed on each other. (b) The structure of the entrance to the active-site cleft is changed between ApH5.5 and ApH9.0, as are the structures of the catalytic residues. (c) The r.m.s.d. values of the Cα atoms of ApH5.5/BpH5.5 and ApH5.5/ApH9.0. (d) B factors of the amino-acid residues of EGPfΔN30 at pH 5.5 (ApH5.5 and BpH5.5) and pH 9.0 (ApH9.0). Hydrogen bonds between the two molecules are indicated by a dotted red line. (e) Catalytic mechanism of EGPf in the first half-reaction. Here, the typical of a retaining enzyme is depicted in a schematic diagram. The two glucose residues correspond to the productive binding mode. pH 9.0: the acidic side chain of Glu178 adjacent to the nucleophile Glu197 maintains a negative charge. pH 5.5: the nucleophile Glu197 maintains a negative charge without the side chain of Glu178.

ISSN: 2053-230X
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