In enzymology, a polynucleotide 5'-phosphatase (EC 184.108.40.206) is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are 5'-phosphopolynucleotide and H2O, whereas its two products are polynucleotide and phosphate.
This enzyme belongs to the family of hydrolases, specifically those acting on phosphoric monoester bonds. The systematic name of this enzyme class is polynucleotide 5'-phosphohydrolase. This enzyme is also called 5'-polynucleotidase.
As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes 1D8H, 1D8I, 1I9S, 1I9T, and 1YN9.