Interaction of Escherichia coli inorganic pyrophosphatase active sites

Escherichia coli inorganic pyrophosphatase (PPase) is a hexamer of identica l subunits, This work shows that trimeric form of PPase exhibits the intera ction of the active sites in catalysis, Some trimer subunits demonstrate hi gh substrate binding affinity typical for hexamer whereas the rest of subun its reveal more than 300-fold substrate affinity decrease. This fact indica tes the appearance of negative cooperativity of trimer subunits upon substr ate binding. Association of the wild-type (WT) trimer with catalytically in active, but still substrate binding mutant trimer into hexameric chimera re stores the high activity of the first trimer, characteristic of trimer inco rporated in the hexamer of WT PPase, Interaction of PPase active sites sugg ests that there are pathways for information transmission between the activ e sites, providing the perfect organization and concerted functioning of th e hexameric active sites in catalysis, (C) 1999 Federation of European Bioc hemical Societies.