Biochemistry 2280A Lecture Notes - Lecture 12: Glycogen Phosphorylase, Pentose Phosphate Pathway, Glycogen Synthase
9 Jun 2016
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The g is very close to 0, so there is an equilibrium between g6p and g1p, they are both energetically favorable. Adding glucose monomers onto one another is unfavorable, so utp hydrolysis is coupled with glycogen synthesis so make it more favorable (the energy input is absolutely necessary) To go backwards, a different enzyme is required because going back using the same path that was favorable would be definition be unfavorable. The other enzyme, for the reverse reaction, is glycogen phosphorylase - nrg input is not required. The two competing enzymes make them both energetically favorable and competing. G6p is the allosteric activator for glycogen synthase and the allosteric inhibitor for glycogen phosphorylase. Atp (indicates that cell energy level is already high) is a glycogen phosphorylase inhibitor. Amp (indicates that cell energy level is quite low) is a glycogen phosphorylase activator. Glucose (high cell energy indicator) is a glycogen phosphorylase inhibitor. Neither atp nor amp regulate glycogen phosphorylase in liver.
