Exopolyphosphatase

In enzymology, an exopolyphosphatase is an enzyme that catalyzes the chemical reaction


 * (polyphosphate)n + H2O $$\rightleftharpoons$$ (polyphosphate)n-1 + phosphate

Thus, the two substrates of this enzyme are (polyphosphate)n and H2O, whereas its two products are (polyphosphate)n-1 and phosphate.

This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides in phosphorus-containing anhydrides. The systematic name of this enzyme class is polyphosphate phosphohydrolase. Other names in common use include metaphosphatase, acid phosphoanhydride phosphohydrolase, and Gra-Pase. This enzyme participates in purine metabolism.

Structural studies
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes, , , and.