3. Glycogen phosphorylase catalyzes the reaction:
(Glycogen is a polymer composed of glucose residues.)
The enzyme is positively cooperative with respect to Pi. AMP is an allosteric activator of the enzyme; ATP is an allosteric inhibitor.
a. Draw v, VS. [Pi] curves for glycogen phosphorylase in the absence of effectors, in the presence of AMP, and in the presence of ATP, all on the same graph.
b. Based on the Monod-Wyman-Changeux (symmetry) model of allosterism, would you expect ATP to bind better to the enzyme in the presence or absence of Pi? Explain your reasoning.