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In enzymology, a bis(5'-nucleosyl)-tetraphosphatase (asymmetrical) (EC 3.6.1.17) is an enzyme that catalyzes the chemical reaction

P₁,P₄-bis(5'-guanosyl) tetraphosphate + H₂O ${\displaystyle \rightleftharpoons }$ GTP + GMP

Thus, the two substrates of this enzyme are P1,P4-bis(5'-guanosyl) tetraphosphate and H₂O, whereas its two products are GTP and GMP.

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 nucleotidohydrolase. Other names in common use include bis(5'-guanosyl)-tetraphosphatase, bis(5'-adenosyl)-tetraphosphatase, diguanosinetetraphosphatase (asymmetrical), dinucleosidetetraphosphatase (asymmetrical), diadenosine P1,P4-tetraphosphatase, dinucleoside tetraphosphatase, and 1-P,4-P-bis(5'-nucleosyl)-tetraphosphate nucleotidohydrolase. This enzyme participates in purine metabolism and pyrimidine metabolism.

Structural studies

As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes 1F3Y, 1JKN, 1KT9, 1KTG, 1XSA, 1XSB, and 1XSC.

References

• Jakubowski H, Guranowski A (1983). "Enzymes hydrolyzing ApppA and/or AppppA in higher plants Purification and some properties of diadenosine triphosphatase, diadenosine tetraphosphatase, and phosphodiesterase from yellow lupin (Lupinus luteus) seeds". J. Biol. Chem. 258 (16): 9982–9. doi:10.1016/S0021-9258(17)44594-7. PMID 6309793.
• Vallejo CG, Lobaton CD, Quintanilla M, Sillero A, Sillero MA (1976). "Dinucleosidasetetraphosphatase in rat liver and Artemia salina". Biochim. Biophys. Acta. 438 (1): 304–9. doi:10.1016/0005-2744(76)90246-1. PMID 181087.
• Warner AH, Finamore FJ (1965). "Isolation, purification, and characterization of P1,P4-diguanosine 5'-tetraphosphate asymmetrical-pyrophosphohydrolase from brine shrimp eggs". Biochemistry. 4 (8): 1568–75. doi:10.1021/bi00884a016. PMID 4955726.

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