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)

1. An activator of the (Ca2+ plus Mg2+)-stimulated ATPase present in the human erythrocytes (membrane) has been isolated in soluble form from hemolysates of these cells. Partial purification has been achieved through use of carboxymethyl-Sephadex chromatography. The resulting activator fraction contained no hemoglobin and only 0.3% of the total adenylate kinase activity of the cell. 2. Whereas the activator was released from erythrocytes subjected to hemolysis in 20 miosM buffer at pH 7.6 or at pH 5.8, only the membranes prepared at pH 7.6 were affected by it. 2. Whereas the activator was released from erythrocytes subjected to hemolysis in 20 miosM buffer at pH 7.6 or at pH 5.8, only the membranes prepared at pH 7.6 were affected by it. 3. When (Ca2+ plus Mg2+)-ATPase activity was measured by 32Pi release from (gamma-32P)ATP, freeze-thawed erythrocytes, as well as membranes prepared at pH 5.8 and at pH 7.6, expressed lower values than noted by assay for total Pi release. When ADP instead of ATP was used as substrate, significant amount of Pi were released by these erythrocyte preparations. Further study revealed (a) production of ATP and AMP from ADP with membranes and hemolysate alone, and (b) exchange of the gamma-and B-position phosphate on (gama-32P)ATP in the presence of membranes plus hemolysates. These observations established the presence of adenylate kinase activity in the (membrane-free) hemolysates and in membranes. It further supports the conclusion that Pi release from ADP by human erythrocytes (freeze-thawed) and by their isolated membranes is due to formation of ATP by adenylate kinase and hydrolysis of this generated ATP by (Ca2+ plus Mg2+)-ATPase. 4. The following points were also established: (a) absence of an ADPase in human erythrocytes; (b) the (Ca2+ plus Mg2+)-ATPase activator enhanced cleavage only of the gama-position of ATP and (c) the (Ca2+ plus Mg2+)-ATPase activator is neither adenylate kinase nor hemoglobin.
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PMID:Studies on an activator of the (Ca2+ plus Mg2+)-ATPase of human erythrocyte membranes. 0 Oct 98

The Lubrol-dispersed guanylate cyclase from sea urchin sperm was purified and isolated essentially free of detergent by GTP affinity chromatography, DEAE-Sephadex chromatography, and gel filtration. After removal of the detergent, the enzyme remained in solution in the presence of 20% glycerol. The specific activity of the purified enzyme was about 12 mumol of guanosine 3':5'-monophosphate (cyclic GMP) formed - min-1 - mg of protein-1 at 30 degrees, an activity about 4600 times that of a soluble guanylate cyclase purified recently from Escherichia coli (Macchia V., Varrone, S., Weissbach, H., Miller, D.L., and Pastan, I. (1975) J. Biol. Chem. 250, 6214-6217). The cyclic GMP phosphodiesterase activity was negligible and adenosine 3':5'-monophosphate (cyclic AMP) phosphodiesterase was not detectable in the purified preparation. Cyclic AMP formation from ATP occurred at a rate of 0.002% of that of guanylate cyclase. In the absence of phosphodiesterase or guanosine triphosphatase inhibitors, 100% of the added GTP was converted to cyclic GMP. The purified enzyme required Mn2+ for maximum activity, the relative rates in the presence of Mg2+ or Ca2+ being less than 0.6% of the rates with Mn2+. The purified enzyme displayed classical Michaelis-Menten kinetics with respect to MnGTP (apparent Km is approximately equal to 170 muM) in contrast to the positively cooperative kinetic behavior displayed by the unpurified, detergent-dispersed, or particulate guanylate cyclase. The molecular weight of the purified enzyme was approximately 182,000 as estimated on Bio-Gel A-0.5m columns equilibrated in the presence or absence of 0.1 M NaCl. The unpurified, detergent-dispersed enzyme also migrated with an apparent molecular weight of 182,000 on columns equilibrated with 0.5% Lubrol WX and 0.1 M NaCl, but it migrated as a large aggregate (molecular weight is greater than 5 X 10(5)) on columns equilibrated in the absence of either the detergent of NaCl. After gel filtration, the unpurified, dispersed enzyme still yielded positive cooperative kinetic patterns as a function of MnGTP. Na dodecyl-SO4 gel electrophoresis of the enzyme after the DEAE-Sephadex or the gel filtration steps resulted in two major protein bands with estimated molecular weights of 118,000 and 75,000. Whether or not these protein bands represent the subunit molecular weights of guanylate cyclase is unknown at present.
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PMID:Sea urchin sperm guanylate cyclase. Purification and loss of cooperativity. 0 69

The mechanism of biosynthetic, transferase, ATPase, and transphosphorylation reactions catalyzed by unadenylylated glutamine synthetase from E. coli was studied. Activation complex(es) involved in the biosynthetic reaction are produced in the presence of either Mg2+ or Mn2+ ; however, with the Mn2+-enzyme inhibition by the product, ADP, is so great that the overall forward biosynthetic reaction cannot be detected with the known assay methods. Binding studies show that substrates (except for NH3 and NH2OH which are not reported here) can bind to the enzyme in a random manner and that binding of the ATP-glutamate, ADP-Pi or ADP-arsenate pairs is strongly synergistic. Inhibition and binding studies show that the same binding site is utilized for glutamate and glutamine in biosynthetic and transferase reactions, respectively, and that a common nucleotide binding site is used for all reactions studied. Studies of the reverse biosynthetic reaction and results of fluorescent titration experiments suggest that both arsenate and orthophosphate bind at a site which overlaps the gamma-phosphate site of nucleoside triphosphate. In the reverse biosynthetic and transferase reactions, ATP serves as a substrate for the Mn2+-enzyme but not for the Mg2+-enzyme. The ATP supported transferase activity of Mn2+-enzyme is probably facilitated by the generation of ADP through ATP hydrolysis. When AMP was the only nucleotide substrate added, it was converted to ATP with concomitant formation of two equivalents of glutamate, under the reverse biosynthetic reaction conditions, and no ADP was detected. The reversibility of 180 transfer between orthophosphate and gamma-acyl group of glutamate was confirmed. ATPase activity of Mg2+ and Mn2+ unadenylylated enzymes is about the same. Both enzymes forms catalyze transphosphorylation reactions between various purine nucleoside triphosphates and nucleoside diphosphates under biosynthetic reaction conditions. The data are consistent with the hypothesis that a single active center is utilized for all reactions studied. Two stepwise mecanisms that could explain the results are discussed.
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PMID:Mechanistic studies of glutamine synthetase from Escherichia coli. An integrated mechanism for biosynthesis, transferase, ATPase reaction. 0 53

The amounts of released soluble (s) antigen of influenza A/WSN virus were increased when the virus was allowed to interact with isolated plasma membranes in a medium containing substances enhancing the level of adenosine 3',5' cyclic monophosphate (c'AMP) or activating the enzyme adenylate cyclase. By contrast, less s-antigen was released upon addition to the incubation medium of foetal calf serum or calf serum proteins which activate c'AMP phosphodiesterase and thus decrease the level of c'AMP. Changes in the amount of released s-antigen were parallelled by changes in the activities of membrane Ca-adenosine triphosphatase and creatine phosphokinase.
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PMID:Interaction of plasma membranes with influenza virus. VI. The possible role of the adenylate cyclase system. 0 18

Binding studies of various nucleotides to the purified coupling factor-latent ATPase from Mycobacterium phlei have been carried out using gel filtration, equilibrium dialysis, and ultrafiltration methods. The purified latent ATPase binds 3 mol of ADP per mol of the enzyme with an apparent dissociation constant of 68 muM. Binding of nucleotides occurred in the decreasing order: ADP, epsilon-ATP, epsilon-ADP, UDP, adenyl-5'-yl imidodiphosphate (AMP-P(NH)P), IDP, and adenosine 5'-(alpha,beta-methylene)diphosphate (AdoP(CH2)P). AMP-P(NH)P inhibits both soluble (Ki = 77 muM) and membrane-bound latent ATPase activity. However, AMP-P(NH)P does not affect oxidative phosphorylation in membrane vesicles of M. phlei. AMP-P(NH)P exhibits one binding site per molecule of the enzyme with a dissociation constant of 71 muM. After trypsin treatment of the enzyme, the binding of ADP decreases 35%, while AMP-P(NH)P binding remains unchanged. Moreover, AMP-P(NH)P binding was not displaced by ADP. Studies with sulfhydryl agents showed that, in contrast to AMP-P(NH)P, binding of at least 1 mol of ADP requires the participation of sulfhydryl groups. The results indicate that AMP-P(NH)P and ADP do not share a common binding site and that the latent ATPase enzyme has separate sites for ATP hydrolysis and ATP synthesis.
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PMID:Binding of nucleotides to purified coupling factor-latent ATPase from Mycobacterium phlei. 1 31

The effect of an inhibitor of adenylate cyclase (ACI) was measured on some enzymes associated with cyclic nucleotide-regulated metabolism. Soluble guanylate cyclase was inhibited; both soluble and particulate cyclic GMP-phosphodiesterases were stimulated. Cyclic AMP phosphodiesterases were unaffected. In contrast, the activities of Na, K-ATPase, protein kinase, phosphorylase kinase, glycogen synthetase and a number of glycosidases were not altered by equipotent amounts of the inhibitor. It is concluded that this substance acts as a modulator of both cyclic AMP and cyclic GMP metabolism in heart and other tissues.
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PMID:The effect of adenylate cyclase inhibitor (ACI) on guanylate cyclase, phosphodiesterase and other enzymes in heart. 1 79

Inhibition of Ca2+-dependent ATPase of sarcoplasmic reticulum membranes (SRM) by platinum and palladium complexes is considerable enhanced during the incubation of these compunds with SRM preparations in the presence of small (10(-5) M) concentrations of ATP or ADP. AMP and nucleotides with non-adenine bases do not have inhibitory effect. To increase the sensitivity of Ca2+-dependent ATPase to platinum and palladium complexes under the action of ATP (but not ADP), the presence of free Ca2+-ions in the medium is required. In the absence of ATP Ca2+-ions do not affect the inhibiting effect of the complexes. The increase in pH of the medium up to 8.5 and the increase of temperature up to 45degree C sharply decrease the ATP ability to enchance the sensitivity of Ca2+-dependent ATPase to platinum and palladium compunds. It is assumed that the ATP ability to enhance Ca2+-dependent ATPase inhibition by platinum and palladium complexes is due to ATP-dependent structural changes in SRM, which increase the availability of certain groups of the enzyme to those compounds.
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PMID:[Inhibitory effect platinum and palladium complexes as indicator of conformational changes in sarcoplasmic reticulum membranes]. 1 49

An enzyme capable to split adenosine triphosphate (ATP) was shown to be firmly associated with mature herpes simplex virus particles purified from infected rabbit lung (ZP) cells. The enzyme localized in the viral envelope was markedly activated by bivalent cations, to the largest degree by Mg2+ at a pH optimum of 7.8--8.0. Na+ and K+ ions neither separately nor together showed any activating effect. Enzyme activity was not sensitive to the action of ouabain. No adenosine diphosphatase (ADPase) and adenosine monophosphatase (AMPase) activities were observed. ATPase activity was competitively inhibited by ADP. AMP and inorganic phosphate were without effect. The ATPase of nuclear membranes isolated from ZP cells exhibited similar properties but behaved differently to the action of sodium dithionite, dinitrophenol, oligomycin and gramicidin, as well as on heat inactivation. The origin of the virus enzyme is discussed.
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PMID:Some properties of the adenosine triphosphatase associated with herpes simplex virus and nuclear membrane of host cells. 2 4

Chromaffin granules isolated from bovine adrenal gland were incubated with (3)H-labelled nucleotides and [(14)C]noradrenaline to study the uptake of these substances. [(3)H]ATP, [(3)H]ADP and [(3)H]AMP are taken up by these organelles by the same temperature-dependent mechanism. The apparent K(m) for ATP and ADP is 1.4mm, and for AMP it is 2.9mm. The uptake of ATP has a flat pH optimum, whereas the catecholamine uptake increases with more alkaline pH. Atractyloside and carboxyatractyloside are competitive and specific inhibitors of nucleotide uptake, whereas reserpine inhibits only that for catecholamines. Mg(2+) ions activate uptake of both catecholamine and nucleotides, whereas EDTA and N-ethylmaleimide inhibit these processes. Nucleotide and catecholamine uptakes are inhibited by uncouplers of oxidative phosphorylation and by two ATP analogues. NH(4) (+) ions and nigericin in the presence of KCl inhibit only catecholamine uptake. It is concluded that nucleotide uptake, as proposed previously for catecholamine uptake, depends on an electrochemical proton gradient produced by a proton-translocating adenosine triphosphatase localized in the membrane of chromaffin granules. Furthermore, as suggested by the effect of NH(4) (+) and nigericin, catecholamine uptake apparently depends on the chemical part of this gradient, whereas the results for nucleotide uptake are consistent with its dependence on the electrical component.
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PMID:A characterization of the nucleotide uptake of chromaffin granules of bovine adrenal medulla. 2 25

Exogenous and endogenously generated reduced pyridine nucleotides caused marked stimulation of O(2) uptake when added to treponemal cell-free extracts, which indicated that terminal electron transport was coupled to the consumption of O(2). Oxidation of reduced nicotinamide adenine dinucleotide (NADH) was shown to correlate stoichiometrically with O(2) reduction, suggesting that NADH was being oxidized through a mainstream respiratory chain dehydrogenase. Oxygen evolution in treponemal extracts was observed after the completion of O(2) uptake which was stimulated by exogenous NADH and endogenously generated reduced NAD phosphate. Oxygen evolution was inhibited by both cyanide and pyruvate, which was consistent with O(2) release from H(2)O(2) by catalase. The addition of exogenous H(2)O(2) to treponemal extracts caused rapid O(2) evolution characteristic of a catalase reaction. A spectrophotometric assay was used to measure ATP formation in T. pallidum cell-free extracts that were stimulated with NADH. P/O ratios from 0.5 to 1.1 were calculated from the amounts of ATP formed versus NADH oxidized. Phosphorylating activity was dependent on P(i) concentration and was sensitive to cyanide, N, N'-dicyclohexylcarbodiimide, and carbonyl cyanide m-chlorophenyl hydrazone. Adenine nucleotide pools of T. pallidum were measured by the firefly luciferin-luciferase assay. Shifts in adenine nucleotide levels upon the addition of NADH to cell-free extracts were impossible to evaluate due to the presence of NAD(+) nucleosidase. However, when whole cells, previously incubated under an atmosphere of 95% N(2)-5% CO(2), were sparged with air, ATP and ADP levels increased, while AMP levels decreased. The shift was attributed to both oxidative phosphorylation and to the presence of an adenylate kinase activity. T. pallidum was also found to possess an Mg(2+) - and Ca(2+) -stimulated ATPase activity which was sensitive to N, N' -dicyclohexylcarbodiimide. These data indicated a capability for oxidative phosphorylation by T. pallidum.
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PMID:Respiration and oxidative phosphorylation in Treponema pallidum. 2 9


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