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)

A new DNA-dependent ATPase was isolated and purified from soluble extracts of Escherichia coli. This enzyme, called ATPase II, has a molecular weight of 86,000 and exists in a monomeric state. It degrades ATP (or dATP) to ADP (or dADP) and Pi in the presence of magnesium and requires a double-stranded polynucleotide as cofactor. A correlation between the efficiency as cofactor and the melting point of the polynucleotide has been found; the lower the melting temperature, the higher the stimulation of ATPase II. The enzyme binds to single-stranded DNA and poly[d(A-T)] copolymer, but not to the double-stranded circular DNA (Form I) of simian virus 40.
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PMID:Purification and characterization of DNA-dependent ATPase II from Escherichia coli. 15 84

Fractions enriched in hCG-binding activity were prepared by differential rate centrifugation of superovulated rat ovarian homogenates and were applied to continuous sucrose density gradients (20-55%). After centrifugation at 63,000 x gav for 3.5 h, fractions of each gradient were collected and assayed for a range of marker enzyme activities characteristic of surface membranes and subcellular organelles. Mitochondria, lysosomes, and rough and smooth endoplasmic reticulum membranes accumulated in the gradient between 38-41% sucrose (1.165-1.180 g/cm3). Nuclei passed through the gradient. However, the various surface membrane markers concentrated in two distinct regions of the gradient. Alkaline phosphatase, phosphodiesterase, (Na+ + K+)ATPase I, and hCG-binding activity concentrated at 29-32% sucrose (1.120-1.135 g/cm3), whereas 5'-nucleotidase, Mg2+-dependent ATPase, and adenylate cyclase activities (and minor peaks of hCG-binding and phosphodiesterase activities) were enriched at 36-38% sucrose (1.16-1.17 g/cm3). A second ATPase, [(Na+ + K+)ATPase II], was also observed in this region of the gradient, which could be distinguished from (Na+ + K+)ATPase I of the light membrane fraction by its sensitivity to the Ca2+-chelating agent, ethylene glycol bis-(aminoethyl)tetraacetic acid (EGTA). The kinetics of binding of radioiodinated hCG to the gonadotropin receptors of the light and heavy membrane fractions were very similar. It is suggested that fractionation of superovulated rat ovaries yields two distinct populations of surface membrane material which have distinct densities and marker enzyme profiles. Furthermore, in contrast to the heavy membrane fraction, light membranes seem to possess considerable amounts of hCG receptor activity but very little adenylate cyclase.
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PMID:Interactions of gonadotropins with corpus luteum membranes. II. The identification of two distinct surface membrane fractions from superovulated rat ovaries. 21 57

Four DNA-dependent ATPases have been isolated from E. coli extracts. ATPases I and III, both sensitive to NEM, require denatured DNA but differ in their heat sensitivity, elution from DEAE-cellulose, and sedimentation coefficient. ATPases II and IV are both resistant to NEM. ATPase II requires partially denatured DNA, whereas ATPase IV can be stimulated by SS DNA. ATPase I is a DNA-unwinding enzyme; ATPase II may be involved in recombination.
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PMID:DNA-dependent ATPases from Escherichia coli K12. 22 6

At least three types of vanadate-insensitive membranous ATPase were identified on rat liver lysosomes: bafilomycin A1-sensitive Mg(2+)-ATPase (H(+)-ATPase), N-ethylmaleimide (NEM)-sensitive but bafilomycin A1-insensitive Mg(2+)-ATPase (ATPase I), and NEM-insensitive Ca2+/Mg(2+)-ATPase (ATPase II). They showed different sensitivity to chemicals and ions with apparent molecular masses of 700-800, 500-650, and 360 kDa, respectively. Of these membranous ATPases, H(+)-ATPase seemed to constitute only one tenth of the ATPase activity on rat liver lysosomes and to be the only ATPase that exposed its active site to the cytoplasmic side of the lysosomal membranes.
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PMID:Three types of membranous ATPase on rat liver lysosomes. 146 9

The inactivation of rec BC (D) DNase upon chromatography on DEAE-cellulose was observed. Simultaneously DNA-stimulated ATPases (I and II) and DNase activities on single- and double-stranded DNA substrates were measured in Escherichia coli rec+ and rec- cell extracts. Normal levels of ATPase I and II were detected in rec+ cells. Rec A- cells were lacking DNA dependent ATPase I, while rec B single and rec BC double mutants were defective in DNA dependent ATPase II, the second major enzyme of this type. Rec B and C mutations did not change DNase activities. Rec A mutation significantly increased DNase activity on linear single-stranded substrate.
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PMID:Rec mutants of Escherichia coli deficient in subunits of rec BC (D) complex. 196 45

The Ca2+-dependent binding of annexin proteins to secretory granule membranes seems to be involved in the early stage of exocytosis. Binding studies have shown that these proteins have a specificity for phosphatidylserine (PtdS) interfaces. Furthermore, aminolipids are necessary for contact and fusion between lipid vesicles or between liposomes and chromaffin granules. Thus, PtdS must be present on the granule outer (cytoplasmic) monolayer. We report here that chromaffin granules possess a mechanism to maintain PtdS orientation, comparable to the ATP-dependent aminophospholipid translocase from human erythrocytes. The translocase, in granules, selectively transports PtdS from the luminal to the cytoplasmic monolayer, provided the incubation medium contains ATP. As this protein shares several properties with the granule vanadate-sensitive ATPase II, we infer that this ATPase, of relative molecular mass 115,000, is the protein responsible for aminophospholipid translocation. This is the first evidence for an ATP-dependent specific phospholipid 'flippase' in intracellular organelles.
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PMID:Control of transmembrane lipid asymmetry in chromaffin granules by an ATP-dependent protein. 254 8

Chromaffin granule membranes were incubated in the presence of low ATP concentrations, at low temperature. A phosphorylated compound was rapidly formed which was stable in 10% trichloroacetic acid at 0 degree C. The lability of this compound in the presence of hydroxylamine or hot trichloroacetic acid indicated an acylphosphate, i.e., an ATPase phosphointermediate. Vanadate but not N-ethylmaleimide inhibited the formation of this derivative. Since the ATP-dependent generation of a transmembrane potential in chromaffin granule vesicles by the H+-pump was inhibited by N-ethylmaleimide but not by vanadate, the acylphosphate should not be associated with the H+-pump, i.e. ATPase I. We suggest that it is associated with ATPase II, an ATPase of unknown function present in chromaffin granule membrane preparations. This hypothesis is supported by the fact that ATPase II is vanadate sensitive and has a molecular mass of 140 kDa, properties similar to those of the phosphorylated intermediate.
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PMID:The acylphosphate present in chromaffin granule membrane preparations is not associated with the proton-pump. 287 89

Chromaffin-granule membranes contain two ATPases, which can be separated by (NH4)2SO4 fractionation after solubilization with detergents, or by phase segregation in Triton X-114. ATPase I (Mr 400000) is inhibited by trialkyltin, quercetin and alkylating agents, and hydrolyses both ATP and ITP. It contains up to five types of subunit, including a low-Mr hydrophobic polypeptide that reacts with dicyclohexylcarbodi-imide; these subunits are unrelated to those of mitochondrial F1F0-ATPase, as judged by size and reaction with antibodies. ATPase II (Mr 140000) is inhibited by vanadate, and is specific for ATP; it has not been extensively purified. Proton translocation by resealed chromaffin-granule 'ghosts', measured by uptake of methylamine or by quenching of the fluorescence of 9-amino-6-chloro-2-methoxyacridine, is supported by the hydrolysis of ATP or ITP, and inhibited by quercetin or alkylating agents, but not by vanadate. ATPase I must therefore be the proton translocator involved in the uptake of catecholamines and possibly of other components of the chromaffin-granule matrix, whereas ATPase II does not translocate protons.
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PMID:Isolation of ATPase I, the proton pump of chromaffin-granule membranes. 300 Mar 54

Two forms of DNA-dependent ATPase activity have been purified from yeast extracts. The two ATPases differ from each other in chromatographic properties and heat stabilities but have similar molecular weight and reaction properties. DNA-dependent ATPase I has been purified to near homogeneity, while DNA-dependent ATPase II is only partially purified. The two ATPases from yeast are related structurally since antiserum raised against ATPase I cross-react against ATPase II. Yeast DNA-dependent ATPase I has a native molecular weight of about 68,000 and consists of a single polypeptide chain. ATPase II also sediments on sucrose gradient as a 68,000-dalton protein. Both yeast DNA-dependent ATPases hydrolyze dNTPs and rNTPs to their corresponding nucleoside diphosphates and orthophosphate, but dATP and ATP are preferred substrates. In addition to nucleoside triphosphates, both enzymes require a divalent cation and a polynucleotide for activity. Single-stranded DNAs and polydeoxynucleotides are the most effective co-substrates for yeast DNA-dependent ATPases. Addition of yeast DNA-dependent ATPases to DNA synthesis system containing yeast DNA polymerases does not significantly stimulate the rate of DNA synthesis.
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PMID:Purification and characterization of two forms of DNA-dependent ATPase from yeast. 610 92

A new DNA-dependent ATPase been purified close to homogeneity from soluble extracts of Bacillus cereus. This enzyme, called ATPase II catalyses the hydrolysis of ATP in the presence of Mg2+ or Ca2+ and DNA. Single-stranded linear DNA is a cofactor about 3-fold more effective than double-stranded DNA. The enzyme catalyses the strand separation of duplex DNA in the presence of ATP. However, at concentrations higher than 0.5 mM, phosphohydrolysis can occur without concomitant DNA unwinding. The enzyme has a molecular weight of 84 000 according to SDS-polyacrylamide gel electrophoresis. ATPase II is inhibited by adenosine 5'-(beta, gamma-imido)-diphosphate, actinomycin D and ethidium bromide, but not by nalidixic acid.
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PMID:DNA-dependent ATPase II from Bacillus cereus. 610 27


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