Evolutionary aspects of inorganic pyrophosphatase

Based on the primary structure, soluble inorganic pyrophosphatases can be d ivided into two families which exhibit no sequence similarity to each other . Family I, comprising most of the known pyrophosphatase sequences, can be further divided into prokaryotic, plant and animal/fungal pyrophosphatases, Interestingly, plant pyrophosphatases bear a closer similarity to prokaryo tic than to animal/fungal pyrophosphatases, Only 17 residues are conserved in all 37 pyrophosphatases of family I and remarkably, 15 of these residues are located at the active site, Subunit interface residues are conserved i n animal/fungal but not in prokaryotic pyrophosphatases, (C) 1999 Federatio n of European Biochemical Societies.