In enzymology, a bis(5'-nucleosyl)-tetraphosphatase (symmetrical) (EC 3.6.1.41) is an enzyme that catalyzes the chemical reaction

P₁,P₄-bis(5'-adenosyl) tetraphosphate + H₂O ${\displaystyle \rightleftharpoons }$ 2 ADP

Thus, the two substrates of this enzyme are P1,P4-bis(5'-adenosyl) tetraphosphate and H₂O, whereas its product is ADP.

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 P1,P4-bis(5'-nucleosyl)-tetraphosphate nucleosidebisphosphohydrolase. Other names in common use include diadenosinetetraphosphatase (symmetrical), dinucleosidetetraphosphatasee (symmetrical), symmetrical diadenosine tetraphosphate hydrolase, adenosine tetraphosphate phosphodiesterase, Ap4A hydrolase, bis(5'-adenosyl) tetraphosphatase, diadenosine tetraphosphate hydrolase, diadenosine polyphosphate hydrolase, diadenosine 5',5-P1,P4-tetraphosphatase, diadenosinetetraphosphatase (symmetrical), 1-P,4-P-bis(5'-nucleosyl)-tetraphosphate, and nucleosidebisphosphohydrolase. This enzyme participates in purine metabolism.

As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 2DFJ and 2QJC.

• Barnes LD, Culver CA (1982). "Isolation and characterization of diadenosine 5',5"'-P1,P4-tetraphosphate pyrophosphohydrolase from Physarum polycephalum". Biochemistry. 21 (24): 6123–8. doi:10.1021/bi00267a015. PMID 6295456.
• Guranowski A, Jakubowski H, Holler E (1983). "Catabolism of diadenosine 5',5"'-P1,P4-tetraphosphate in procaryotes. Purification and properties of diadenosine 5',5"'-P1,P4-tetraphosphate (symmetrical) pyrophosphohydrolase from Escherichia coli K12". J. Biol. Chem. 258 (24): 14784–9. doi:10.1016/S0021-9258(17)43729-X. PMID 6317672.