Nucleoside Triphosphate Pyrophosphohydrolase
Bis(5'-nucleosyl)-tetraphosphatase (asymmetrical)
Diguanosinetetraphosphatase (asymmetrical)
Dinucleosidetetraphosphatase (asymmetrical)
1-P,4-P-bis(5'-nucleosyl)-tetraphosphate nucleotidohydrolase
LYS 36(Magnesium-2);GLU 52; (Magnesium-1);GLU 56(Magnesium-1,2)
LYS 36(Magnesium-2);GLU 52;GLU 103(Magnesium-1);GLU 56(Magnesium-1,2)
LYS 47(Magnesium-2); ;GLU 115(Magnesium-1);GLU 67(Magnesium-1,2)
LYS 42(Magnesium-2);GLU 58;GLU 110(Magnesium-1);GLU 62(Magnesium-1,2)
Regiospecificity of the hydrolysis of diadenosine polyphosphates catalyzed by three specific pyrophosphohydrolases.
The three-dimensional structure of the Nudix enzyme diadenosine tetraphosphate hydrolase from Lupinus angustifolius L.
NUCLEOTIDE SEQUENCE [GENOMIC DNA], X-RAY CRYSTALLOGRAPHY (2.0 ANGSTROMS), FUNCTION, COFACTOR.
Cloning, characterisation and crystallisation of a diadenosine 5',5"'-P(1),P(4)-tetraphosphate pyrophosphohydrolase from Caenorhabditis elegans.
Crystallization of a complex of Caenorhabditis elegans diadenosine tetraphosphate hydrolase and a non-hydrolysable substrate analogue, AppCH2ppA.
X-RAY CRYSTALLOGRAPHY (1.8 ANGSTROMS), SUBUNIT.
The crystal structure of diadenosine tetraphosphate hydrolase from Caenorhabditis elegans in free and binary complex forms.
The structure of Ap(4)A hydrolase complexed with ATP-MgF(x) reveals the basis of substrate binding.
Analysis of the catalytic and binding residues of the diadenosine tetraphosphate pyrophosphohydrolase from Caenorhabditis elegans by site-directed mutagenesis.
Structures and mechanisms of Nudix hydrolases.
Structure and substrate-binding mechanism of human Ap4A hydrolase.
1H, 13C, and 15N resonance assignments of the 17 kDa Ap4A hydrolase from Homo sapiens in the presence and absence of ATP.
This enzyme belongs to Nudix (nucleoside diphosphate linked to X) hydrolase superfamily. The family of this enzyme (asymmetrical Ap4A hydrolase) can be subdivided into two groups: the "animal-type" group that includes the enzymes from animal and archaea, and the "plant-type" one that includes ones from plant and bacteria (see [5]). This enzyme belongs to the animal-type group. The plant-type enzymes correspond to the entry S00920 in EzCatDB. According to the literature [8], Mg-3 is bound to the three phosphates of the leaving ATP, which are phosphates-1, -2 and -3 of substrate Ap4A. The catalytic water is bound to Mg-1, which is coordinated by Glu52, Glu56 and Glu103 (of 1ktg). Mg-2 is coordinated by mainchain carbonyl of Lys36, sidechain of Glu56, and phosphates-2 and -3. The reaction of this enzyme may proceed as follows (see [5], [7] and [8]). (1) Glu52 (of 1ktg) acts as a general base to deprotonate the water molecule, which is bound to Mg-1. Mg-1, which is bound to Glu52, Glu56 and Glu103, may lower the pKa of the catalytic water, so that it can be deprotonated easily. (2) The activated water makes a nucleophilic attack on phosphate-4 of Ap4P. (3) Mg-2 and Mg-3 stabilize the negative charge on the leaving phosphate groups of ATP. The sidechains of Lys36 and Lys83 also stabilize the negative charge as well. The nucleophilic substitution reaction seems to be SN2-like.