Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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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)

An ATPase was purified from mouse myeloma MOPC 70E the activity of which depends on the presence of single-stranded DNA and divalent cations such as Mg2+, Mn2+, Ca2+, Ni2+ or Fe2+. The enzyme splits both ribonucleoside and deoxyribonucleoside triphosphates but preferentially ATP and dATP yielding nucleoside diphosphates and inorganic phosphate. The enzyme has an absolute requirement for single-stranded DNA. Alternating double-stranded polydeoxynucleotides are only slight effective, and native double-stranded DNA, single-stranded and double-stranded RNAs as well as DNA - RNA hybrids are ineffective in stimulating the ATPase. The enzyme has further characterized by sedimentation in a sucrose density gradient (s20, w = 5.5 S) and by isoelectric focussing in an ampholine pH gradient (pI = 6.5).
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PMID:An ATPase depending on the presence of single-stranded DNA from mouse myeloma. 12 26

The relationship between the RNA-dependent beta-gamma ATPase in purified rho preparations and rho-mediated termination of transcription has been investigated. In a purified in vitro system, transcription from lambdagal DNA has been carried out using either ribonucleoside triphosphates (NTPs) or four ribonucleoside 5'-(beta-gamma-imino)triphosphates (NMP-P(NH)Ps) as RNA precursors. In the presence of NTPs, rho termination activity results in (a) the synthesis of rho-dependent transcripts which are of discrete size by polyacrylamide gel analysis and (b) a marked reduction by hybridization assay in RNA transcribed distal to the rho-sensitive termination site tR. In the presence of four NMP-P(NH)Ps, which are not substrates for the beta-gamma ATPase, termination by rho is completely abolished, whereas rho-independent termination occurs normally. Addition of ATP to transcription reactions containing four NMP-P(NH)Ps restores termination, ruling out the possibility that the termination activity of rho is nonspecifically inhibited by the analog preparations. We interpret our data as strongly suggesting that the RNA-dependent beta-gamma ATPase activity of rho is required for rho-mediated termination of transcription.
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PMID:ATPase activity required for termination of transcription by the Escherichia coli protein factor rho. 13 Nov 27

The purification of p protein to homogeneity from Escherichia coli has shown that its RNA-dependent ATPase activity is physically inseparable from its termination activity. The biochemical properties of pATPase have been studied using poly(C) as the activating RNA. This reaction is stimulated by Mg2+ ions and Mn2+ ions and is prevented by excess EDTA; it is not stimulated by Ca2+ ions. The reaction is not affected by a Zn2+ ion chelator and is inhibited by 1 mM Zn2+. With Mg2+ present, the activity is essentially constant from pH 7 to pH 9.7. pATPase is sensitive to p-hydroxymercuribenzoate and to N-ethylmaleimide. All four ribonucleoside triphosphates are hydrolyzed by p action. ATP has the lowest Km (0.009 mM), while CTP has the highest Vmax. In a mixture containing all four nucleoside triphosphates at a concentration of 0.4 mM, p shows no strong preference for any one of the substrates. The response of p ATPase to a variety of inhibitors of other ATPases and GTPases and of transcription has been studied. Of the compounds tested, aurintricarboxylic acid, an inhibitor of protein-nucleic acid interactions, was found to be a potent inhibitor of p ATPase, while rifampicin and heparin had no effect. pATPase showed partial sensitivity to thiostrepton, fusidic acid, Dio 9, and sodium azide.
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PMID:Characterization of the nucleoside triphosphate phosphohydrolase (ATPase) activity of RNA synthesi termination factor p. I. Enzymatic properties and effects of inhibitors. 13 81

1. Tightly bound ATP and ADP, found on the isolated mitochondrial ATPase, exchange only slowly at pH 8, but the exchange is increased as the pH is reduced. At pH 5.5, more than 60% of the bound nucleotide exchanges within 2.5 min. 2. Preincubation of the isolated ATPase with ADP leads to about 50% inhibition of ATP hydrolysis when the enzyme is subsequently assayed in the absence of free ADP. This effect, which is reversed by preincubation with ATP, is absent on the membrane-bound ATPase. This inhibition seems to involve the replacement of tightly bound ATP by ADP. 3. Using these two findings, the binding specificity of the tight nucleotide binding sites was determined. iso-Guanosine, 2'-deoxyadenosine and formycin nucleotides displaced ATP from the tight binding sites, while all other nucleotides tested did not. The specificities of the tight sites of the isolated and membrane-bound ATPase were similar, and higher than that of the hydrolytic site. 4. The nucleotide specificities of 'coupled processes' nucleoside triphosphate-driven reversal of electron transfer, nucleoside triphosphate-32Pi exchange and phosphorylation were higher than that of the hydrolytic site of the ATPase and similar to that of the tight nucleotide binding sites.
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PMID:Specificity of nucleotide binding and coupled reactions utilising the mitochondrial ATPase. 15 44

The single-stranded DNA-dependent ribonucleoside triphosphatase activity of the Escherichia coli dnaB gene product was characterized. Purine ribonucleoside triphosphates were the preferred substrates, but all ribonucleoside triphosphates were cleaved at the gamma position to yield ribonucleoside diphosphates and Pi. The enzyme required Mg2+, which could be replaced by Mn2+ but with lower activity. The pH optimum was 7.5 in either Tris-HCl or phosphate buffer. The Km for MgATP was 0.59 mM and the Vmax was 8.7 nmol/min/microgram of protein at 30 degrees. The DNA requirement was best satisfied with either fd or phiX174 single-stranded DNA (Km 0.033 mM nucleotides); maximal rate of nucleoside diphosphate formation occurred with 1 dnaB molecule/fd or phiX174 single-stranded DNA molecule. The dnaB gene product was found to have hysteretic properties and the hysteresis appeared to be due to a dissociation and reassociation of the enzyme.
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PMID:The dnaB gene product of Escherichia coli. II. Single stranded DNA-dependent ribonucleoside triphosphatase activity. 20 60

The activities of dTMP kinase (ATP-deoxythymidine monophosphate phosphotransferase, EC 2.7.4.9), 5'-nucleotidase (5'-ribonucleoside phosphohydrolase, EC 3.1.3.5), adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4), AMP deaminase (AMP aminohydrolase, EC 3.5.3.6) and ATP-(Mg2+)-ase (ATP phosphohydrolase, EC 3.6.1.3) were assayed in mitochondria of normal and regenerating rat liver. In regenerating mitochondria, the dTMP kinase activity increased 20 times, 5'-nucleotidase (5'Nase) activity for dTMP diminished by 65% and its activity for other nucleoside monophosphates did not change; adenosine deaminase activity for adenosine (AR) increased by 40%, but for deoxyadenosine (AdR) decreased by 70%. AMP deaminase and ATP-(Mg2+)-ase activities behaved similarly in mitochondria from regenerating liver, decreasing by 70 and 64% respectively. The changes of the amount of dTMP in mitochondria depend on enzyme activities which regulate the AdR concentration.
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PMID:Relationship between 5'-nucleotidase, adenosine deaminase, AMP deaminase, ATP-(Mg2+)-ase activities and dTMP kinase activity in rat liver mitochondria. 22 41

Extracts of the DNA initiation-defective mutant Escherichia coli dnaB252 are inactive in a dnaB complementation assay but yield a ribonucleoside triphosphatase activity of native molecular weight of about 270,000 (60,000-dalton polypeptide as subunit) that can be inactivated by antibody to dnaB. On the other hand, extracts of a dnaB252(P1 bac) lysogen, in which the dnaB mutation is suppressed in vivo by the constitutive expression of the P1 dnaB analog (ban protein), are active in dnaB complementation and the activity is also sensitive to dnaB antibody. Upon further purification two proteins (with polypeptide molecular weights of 60,000 and 56,000, respectively) are found associated with each other (native molecular weight about 270,000). The larger and the smaller protein are tentatively identified as the dnaB and P1 ban protein. It is suggested that suppression of the dnaB mutation by prophage P1 bac is accomplished by a stabilization of dnaB252 by P1 ban subunit molecules in a heteromultimer.
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PMID:Escherichia coli dnaB mutant defective in DNA initiation: isolation and properties of the dnaB protein. 34 77

The purification of the Escherichia coli dnaB protein by affinity chromatography on nucleotides bound to agarose is described. The dnaB protein, which contains an associated ribonucleoside triphosphatase activity (Wickner, S., Wright, M., and Hurwitz, J. (1974) Proc. Natl. Acad. Sci. U. S. A. 71, 783-787) binds to immobilized ATP, ADP, and UDP, but not to AMP. The type of linkage of ATP to agarose influences the adsorption, elution, and purification of the enzyme. Optimal purification is achieved using ATP bound to agarose via its oxidized ribose moiety. By this means, the dnaB protein can be obtained at least 95% electrophoretically pure after only three purification steps. The enzyme can be eluted from immobilized nucleoside-5'-di- and -triphosphates by ATP, ADP, and pyrophosphate, but not by AMP or orthophosphate. ADP and pyrophosphate, as well as the substrate ATP in high concentration are at the same time inhibitors of the ribonucleoside triphosphatase. The dnaB complementing and ribonucleoside triphosphatase activities could not be separated from each other by affinity chromatography, supporting the finding of others that they both reside on the same protein complex, namely a dnaB multimer. The results indicate that the dnaB protein binds to immobilized nucleotides by means of its ribonucleoside triphosphatase, and that at least the pyrophosphate moiety is essential for adsorption as well as elution of the enzyme.
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PMID:Escherichia coli dnaB protein. Affinity chromatography on immobilized nucleotides. 35 57

The T4 bacteriophage gene 41 protein is known from genetic analysis to be essential for phage DNA replication in vivo. It became possible to monitor the activity of this protein during purification after development of an "in vitro complementation assay," which measures its stimulation of DNA synthesis in a concentrated crude lysate prepared from Escherichia coli cells infected with a T4 bacteriophage mutant in gene 41 (L. Moran and B. Alberts, manuscript in preparation). In this report, a purification procedure involving three chromatographic steps is described which reproducibly yields a 90% homogeneous preparation of this rather unstable protein. The major polypeptide chain present (58,000 daltons) is shown to cosediment with a DNA-dependent GTPase (and ATPase) activity, and to induce extensive in vitro DNA synthesis on both single- and double-stranded DNA templates when incubated with our preparations of five other purified T4 DNA replication proteins (plus deoxyribonucleoside and ribonucleoside triphosphates).
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PMID:Purification of gene 41 protein of bacteriophage T4. 37 35

Purified E. coli dnaB and dnaC(D) gene products interact physically and functionally in vitro. This interaction was demonstrated as follows: (a) A complex of dnaB and dnaC(D) gene products was isolated by gel filtration; ATP specifically was required for isolation of the complex. (b) The DNA-independent ribonucleoside triphosphatase activity associated with dnaB gene product was inhibited by dnaC(D) gene product. (c) The dnaC(D) gene product was protected from inactivation by N-ethyl-maleimide by the combination of dnaB gene product and ATP; this protection required ATP specifically.
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PMID:Interaction of Escherichia coli dnaB and dnaC(D) gene products in vitro. 109 74


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