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Figure 2.
Fig. 2. The carbohydrate recognition site of AAL. (a) The
dimer structure of the rAAL–lactose complex. The lactose and
sulfate ions bound to the CRD concave of AAL are shown in a
ball-and-stick model. (b) The electrostatic potential map on the
rAAL surface showing a positively charged cavity bound with
lactose. (c) The carbohydrate recognition site bound with
lactose. Residues of AAL and lactose involved in recognition are
shown. The F[o ]− F[c] omit electron density map is calculated
without the ligand and contoured at 3.0σ. (d) The interactions
between lactose and AAL. A total of 10 hydrogen bonds are
involved in contacts between six residues and lactose. Residues
Asn43, His59, Asn72, and Trp80 are involved in galactose moiety
reorganization, whereas residue Arg85 is involved in glucose
moiety, and Arg63 and Glu83 contact both galactose and glucose
moieties. In these figures, lactose, sulfate ion, and residues
involved in recognition are represented as a ball-and-stick
model.
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