Figure 4: Substrate recognition by the GT domain active site. | Nature Communications

Figure 4: Substrate recognition by the GT domain active site.

From: Crystal structure of glycogen debranching enzyme and insights into its catalysis and disease-causing mutations

Figure 4

(a) Difference electron-density map for the oligosaccharides bound at the GT domain active site. The map shown here and in Fig. 5a was calculated before oligosaccharides were incorporated in the atomic model, and contoured at 2 σ. (b) Accommodation of oligosaccharide M by the GT domain active site. (c) Accommodation of oligosaccharide B by the GT domain active site. Part of the nearby oligosaccharide M is also shown. The +1 and −1 saccharide units of acarbose in the Taka-amylase A structure (PDB 7TAA, grey for the carbon atoms) is shown in partial transparency. They mimic the +1 and −1 residues in the substrate. (d) Specific debranching activities of the W470A mutant and its combinations with mutants possessing only the GT or the GC activities.

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