Pyrophosphate may be involved in regulation of bacterial glycogen synthesis

Inorganic pyrophosphate is a potent inhibitor of the enzyme that catalyzes synthesis of the glucosyl donor for Escherichia coli glycogen synthesis, ADP-glucose pyrophosphorylase. The K i is determined to be 40 μM and the substrate ATP, the activator, fructose 1,6-P 2 or the allosteric inhibitor, AMP do not greatly affect the inhibition. PP i exhibits mixed type inhibition with the other substrate, glucose 1-P. The potential regulation of glycogen synthesis by PP i is discussed.