Regulation of adenosine diphosphate glucose synthase from Escherichia coli. Interactions of adenylate energy charge and modifier concentrations.

The adenosine diphosphate glucose synthase (pyrophosphorylase) of Escherichia co2i responds very sharply to variation in the energy charge of the adenylate pool. The response is in the right direction to insure that this enzyme, which catalyzes the &-St step unique to glycogen storage in E. coli, will have appreciable activity only under conditions of energy excess (high energy charge). The positive response to high energy charge is strongly enhanced by reduced triphosphopyridine nucleotide, fructose 1,6-diphosphate, 3-phosphoglyceraldehyde, and phosphoenolpyruvate. High concentrations of these metabolites seem appropriate as signals for energy storage.