Galactose/glucose binding protein

D-Galactose/D-glucose binding protein compiexed with /3-D-giucose (Gic)... 

In the bacterium E. coli, glucose is taken up by group translocation, lactose is taken up by secondary active transport (using H + ), and maltose is taken up by means of a binding-protein system. Outline how it would be possible to determine whether melibiose (a disaccharide of glucose and galactose) is taken up by . coli and. if it is, whether one of the mechanisms described earlier applies. 

Figure 1. Stereo view of the hydrogen-bonding and stacking interactions between the D-galactose-binding protein (GBP) and D-glucose. The glucose is sandwiched between Phe 16 and Trp 183.

Figure 3 Representation of the interactions responsible for binding of D-glucose inside the active site of the galactose-binding protein from E. coli. The array of hydrogen bonds and the functional groups involved are shown schematically on the left-hand side. This representation also illustrates the sandwiching of the substrate between two aromatic subunits. The picture on the right-hand side shows the arrangement in the crystal with the same color code.

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