3. Researchers studying the enzyme glucosamine-6-phosphate synthase have measured the dissociation constant for d-glucosamine-6-phosphate [3.8 x 10^-4 M] and 2-deoxy- d -glucose-6-phosphate [4.6 (0.7) x 10^-2]. Are these values consistent with the hypothesis that the enzyme makes a hydrogen bond with the amino group of glucosamine and that water cannot replace the amine when 2-deoxy- d -glucose-6-phosphate binds? Draw the structures of these sugar derivatives bound to glucosamine-6-phosphate synthase and explain how you came to your conclusion. A typical hydrogen bond in a biomolecule has an energy of ~15 kJ/mol.

Suggestion: Write out the two dissociation reactions. Combine them to show one substrate swapping for the other and determine the free energy change associated with that.

cosamine-6-phosphate D-glucosamine-6-phosphate KD=3.8104M KD=4.6104M