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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dinucleosidetriphosphatase (EC 3.6.1.29) is present in both the 37,000 g rat liver supernatant and precipitate (50 mU/g each fraction). These two activities show matching molecular weights, isoelectric points, substrate specificities, Km values, bivalent cation requirements and inhibition by zinc (II). The particulate triphosphatase and a residual dinucleosidetetraphosphatase (EC 3.6.1.17) are solubilized by freeze-thawing or by Triton X-100. Detergent treatment also extracts an unspecific phosphodiesterase I activity (EC 3.1.4.1) which also splits dinucleoside polyphosphates. The above findings suggest the occurrence of cytosolic and particulate degradative pathways for dinucleoside polyphosphates.
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PMID:Occurrence of dinucleosidetriphosphatase in the cytosol and particulate fractions from rat liver. 299 62

Rat liver dinucleoside triphosphatase (EC 3.6.1.29) is associated with sucrose-gradient purified mitochondria and can be extracted by freeze and thaw treatment. The proportion of mitochondrial dinucleoside triphosphatase approaches 50% of total liver enzyme. Evidence is also presented that 10% of total liver bis(5'-guanosyl)tetraphosphatase (EC 3.6.1.17) might be equally linked to mitochondria. Those data suggest that diadenosine 5',5'''-P1,P3-triphosphate, diadenosine 5',5'''-P1,P4-tetraphosphate, or other substrates of those enzymes, might be somehow related to mitochondria or mitochondrial function(s), although the occurrence of dinucleoside polyphosphates has not been reported in that organelle.
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PMID:Mitochondrial location of rat liver dinucleoside triphosphatase. 300 92

The formation of a complex between Zn(II) and beta-D-fructose 2,6-bisphosphate was shown because the latter compound: activated bis(5'-guanosyl)tetraphosphatase (EC 3.6.1.17) and dinucleoside triphosphatase (EC 3.6.1.29) only to the extent that they could be inhibited by Zn(II); increased the consumption of Zn(II) necessary to titrate to an end point a solution of the metallochromic indicator eriochrome black T; coeluted with Zn(II) in a gel filtration column capable of resolving them if unbound. Neither of those effects was shown by D-fructose 1,6-bisphosphate under the same conditions.
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PMID:Binding of zinc(II) to beta-D-fructose 2,6-bisphosphate. 303 Mar 15

Three distinct enzymes hydrolyzing either ApppA or AppppA, or both, were separated and purified from yellow lupin seed extracts. Two of the enzymes were purified to homogeneity. These enzymes differ greatly in their catalytic and physical properties. One hydrolase, with a native molecular weight of 41,000, exhibits broad pH (from 5-8) optimum for activity, requires Mg2+ for activity, is inhibited by zinc ions (I0.5 = 25 microM) and hydrolyses ApppA (V = 1), ApppC (V = 0.38), ApppG (V = 0.2), and ribose(5')pppA (V = 0.2). The enzyme exhibits much lower activity with AppppA (V = 0.1), and ApppppA, AppppppA, ppppA, and ATP are hydrolyzed 25- to 100-fold slower then ApppA. ADP was always one of the products of the reactions catalyzed by the enzyme. AppA, NAD, NADP, FAD, cAMP, and p-nitrophenyl-thymidine 5'-phosphate were not hydrolyzed by the enzyme. The enzyme is diadenosine 5',5"'-P1, P3-triphosphatase. The second hydrolase, composed of one polypeptide chain of a molecular weight 18,000-18,500, exhibits optimal activity in the pH range from 7.5-9, requires Mg2+ for activity, is inhibited by calcium ions (I0.5 for calcium depends on the concentration of Mg2+ and is 35-180 microM in the presence of 0.5-10 mM Mg2+, respectively), and hydrolyzes AppppA (V = 1, Km = 1 microM), ApppppA (V = 0.42, Km = 1.8 microM), AppppppA (V = 0.34), AppppU (V = 0.73), AppppC (V = 0.67), AppppG (V = 0.27), and ppppA. ATP was always one of the products of the reactions catalyzed by the enzyme. Dinucleoside di- and triphosphates, ATP, cAMP, and p-nitrophenylthymidine 5'-phosphate were not hydrolyzed by the enzyme. This enzyme is diadenosine 5',5"'-P1,P4-tetraphosphatase (EC 3.6.1.17). The third hydrolase, composed of one polypeptide chain of a molecular weight of 56,000, exhibits maximal activity at pH 9-10.5, does not require Mg2+ ions for activity, is inhibited neither by divalent cations (Mg2+, Ca2+, Zn2+, Co2+, Mn2+, or Ni2+) nor by EDTA, and uses as substrates all compounds which are substrates for the diadenosine 5',5"'-P1,P3-triphosphatase and diadenosine 5',5"'-P1,P4-tetraphosphatase. In addition, the enzyme hydrolyzes p-nitrophenyl-thymidine 5'-phosphate, p-nitrophenylthymidine 3'-phosphate, bis-p-nitrophenylphosphate, ADP, AppA, NAD, NADP, and FAD, but not cAMP. With the exception of p-nitrophenylphosphate derivatives all other substrates of the enzyme yield AMP as one of the products of hydrolysis. This enzyme has a specificity similar to that of phosphodiesterases (EC 3.1.4.1) from other sources. With the lupin phosphodiesterase, ApppA (V = 1, Km = 2.2 microM) and AppppA (V = 1, Km = 2.0 microM) are better substrates than NAD (V = 0.8, Km = 9.6 microM), AppA (V = 0.4), ApppppA (V = 0.6), and AppppppA (V = 0.34).
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PMID: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. 630 93

This article presents a fluorimetric study of the main properties of the enzymes dinucleoside tetraphosphate (asymmetrical) hydrolase or dinucleoside tetraphosphatase (Ap4Aase, EC 3.6.1.17) and dinucleoside triphosphate hydrolase or dinucleoside triphosphatase (Ap3Aase, EC 3.6.1.29), both present in adrenal medulla cytosolic extracts. Diethenoadenosine polyphosphates, epsilon-(ApnA), are used as artificial fluorogenic substrates. Ap4Aase exhibits a molecular mass around 20 kDa and neutral optimum pH (7.0-7.5). It requires Mg2+ and preferentially hydrolyzes substrates with four phosphate groups. Km for epsilon-(Ap4A) is 1.3 microM and Ki for Ap4A and Gp4G are 1 and 0.2 microM respectively. Km for Ap4A determined by HPLC is 1.6 microM. epsilon-(Ap5A) and epsilon-(Ap6A) are hydrolyzed at reduced rates. This enzyme is inhibited by Zn2+, F- and very strongly by Ap4 and epsilon-Ap4. Ca2+ cannot replace Mg2+, but behaves as inhibitor in its presence. The substrate analogs dinucleoside triphosphates Ap3A, G;3G, m7Gp3G and m7Gp3A and the periodate-oxidized nucleotides o-(Ap4A), o epsilon-(Ap4A), o-Ap4 and o epsilon-Ap4 behave as inhibitors. Ap3Aase exhibits a molecular mass around 30 kDa and neutral optimum pH (7.0-7.5). It requires Mg2+ or Ca2+, but retains a low measurable activity around 10% in the absence of these divalent cations. It only hydrolyzes substrates with three phosphate groups. Km for epsilon-(Ap3A) is 11 microM and Ki for Ap3A and Gp3G are 20 and 22 microM, respectively. Km for Ap3A determined by HPLC is 16 microM. m7Gp3G and m7Gp3A are also good substrates for triphosphatase.
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PMID:Specific dinucleoside polyphosphate cleaving enzymes from chromaffin cells: a fluorimetric study. 749 90