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

Ca2+ is a powerful inhibitor (Ki is congruent to 16 muM) of basal and prostaglandin E1 (PGE1)-stimulated adenylate cyclase [ATP pyrophosphate-lyase (cyclizing); EC 4.6.1.1] activity in membranes obtained from homogenized human platelets. Ca2+ (but not the ionophore A23,187) decreased V(max) of the reaction without an effect on the Ks for ATP. Neither ATP nor PGE1 affected Ki for Ca2+. In intact platelets A23,187 induced Ca2+ influx and markedly inhibited PGE1-stimulated rise in adenosine 3':5'-cyclic monophosphate (cAMP) levels. Guanylate cyclase [GTP pyrophosphate-lyase (cyclizing); EC 4.6.1.2] activity was mainly found in the soluble fraction (greater than 90%). Both soluble and membrane bound enzymes were stimulated by Mn2+ and Ca2+ and inhibited by Zn2+. Adenylate and guanylate cyclase activity were both present in a membrane fraction cyclase activity were both present in a membrane fraction which contained Ca2+ activated ATPase activity, and accumulated Ca2+ from the medium in the presence of ATP and oxalate. Other evidence indicates that these membranes originated in large part from the dense tubular system of the platelets. It is proposed that concurrent inhibition of adenylate cyclase and stimulation of guanylate cyclase facilitates the direct initiating effect of Ca2+ on platelet secretion and aggregation.
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PMID:Interrelationships between Ca2+ and adenylate and guanylate cyclases in the control of platelet secretion and aggregation. 0 60

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

Anthopleurin-A (AP-A), a polypeptide with MW ca. 5500 (53 amino acids), isolated from the sea anemone, Anthopleura xanthogrammica (Brandt), elicited a potent positive inotropic effect but without an accompanying chronotropic effect on the isolated cardiac muscles of rat, rabbit, guinea pig and cat. Similarly in dogs and cats in situ, i.p. injections of AP-A increased the contractile force without effect on heart rate or blood pressure. The cardiotonic potency for AP-A was equivalent to that of isoproterenol but much greater than that for ouabain or glucagon on the isolated cardiac muscle. AP-A increased the contractile force (cardiac output) and decreased atrial pressure in dog heart during pentobarbital-induced failure. This inotropic effect was not inhibited by propranolol pretreatment. The Ca++ requirement to restore the contractile force was less in AP-A-treated than in ouabain or isoproterenol-treated tissues. After AP-A treatment, the cardiac contractility was more resistant to hypoxia and to low or high temperature stress than ouabain-treated or control preparations. AP-A at 5 10(-9) M increased the duration of the action potential, its mean rate of rise and conduction in the guinea-pig atria and ventricles. At the maximum effective concentration, AP-A did not inhibit Na+, K+-activated adenosine triphosphatase, phosphodiesterase (high Km and low Km) and cyclic 3',5'-adenosine monophosphate content of guinea-pig heart. AP-A (5 X 10(-8) to 5 X 10(-7) M) neither contracted nor relaxed the isolated vascular smooth muscle. The results suggest that AP-A may be useful in the clinical management of cardiac failure and as an experimental tool to study the pharmacology and physiology of cardiac muscle.
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PMID:A polypeptide (AP-A) from sea anemone (Anthopleura xanthogrammica) with potent positive inotropic action. 1 Apr 26

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

Luminal brush border and contraluminal basal-lateral segments of the plasma membrane from the same kidney cortex were prepared. The brush border membrane preparation was enriched in trehalase and gamma-glutamyltranspeptidase, whereas the basal-lateral membrane preparation was enriched in (Na+ + K+1)-ATPase. However, the specific activity of (Na+ + K+)-ATPase in brush border membranes also increased relative to that in the crude plasma membrane fraction, suggesting that (Na+ + K+)-ATPase may be an intrinsic constituent of the renal brush border membrane in addition to being prevalent in the basal-lateral membrane. Adenylate cyclase had the same distribution pattern as (Na+ + K+)-ATPase, i.e. higher specific activity in basal-lateral membranes and present in brush border membranes. Adenylate cyclase in both membrane preparations was stimulated by parathyroid hormone, calcitonin, epinephrine, prostaglandins and 5'-guanylylimidodiphosphate. When the agonists were used in combination enhancements were additive. In contrast to the distribution of adenylate cyclase, guanylate cyclase was found in the cytosol and in basal-lateral membranes with a maximal specific activity (NaN3 plus Triton X-100) 10-fold that in brush border membranes. ATP enhanced guanylate cyclase activity only in basal-lateral membranes. It is proposed that guanylate cyclase, in addition to (Na+ + K+)-ATPase, be used as an enzyme "marker" for the renal basal-lateral membrane.
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PMID:Preparation of renal cortex basal-lateral and bursh border membranes. Localization of adenylate cyclase and guanylate cyclase activities. 1 97

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


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