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)

The Arrhenius plots for the membrane-bound ATPase and its soluble form purified from Micrococcus lysodeikticus, presented discontinuities near 30 degrees C at pH 7.5. Glycerol-containing lipids were not responsible for these discontinuities. The values of the enthalpies of activation were 12 (soluble) and 22 (membrane-bound) kcal/mol (50.2 and 92.0 kJ/mol) above 30 degrees C and 42 (soluble) and 29 (membrane-bound) kcal/mol (175.7 and 121.3 kJ/mol) below that temperature. The results suggested that both molecular forms of the ATPase were able to adopt at least two different structures, above and below the critical temperature. Of the two, only the high-temperature structure seemed to be enzymically active. In the case of lipid-dependent ATPases, such as the Escherichia coli enzyme, the transition between both enzyme structures probably occurred with simultaneous "melting" of their lipid microenvironment.
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PMID:Activation parameters of the adenosine triphosphatase of Micrococcus lysodeikticus. A comparison of the soluble and membrane-bound forms of the enzyme. 13 1

It is shown that the properties of ATPase (EC 3.6.1.3) of Micrococcus luteus depend only to some extent on the state of the membrane to which it is attached. Its interaction with the membrane appears to be largely controlled by polar forces. It is shown, however, that the UV-sensitivity of the membrane-bound ATPase is also significantly influenced by the state of membrane lipids.
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PMID:Response of membrane-bound ATPase of Micrococcus luteus to heat and ultraviolet light. 13 90

1. The activities of some membrane-bound enzymes such as adenylate cyclase, Na+ + K+-stimulated adenosine triphosphatase (Na+ + K+-ATPase), Ca2+-stimulated ATPase and Mg2+-stimulated ATPase were examined in heart sarcolemmal fractions from control and cardiomyopathic hamsters at different stages of heart failure. 2. The basal adenylate cyclase activity in sarcolemma from cardiomyopathic animals with early, moderate and late stages of heart failure was not different from the control values whereas the sodium fluoride- and catecholamine-stimulated adenylate cyclase activities were depressed in cardiomyopathic sarcolemma at moderate and late stages. 3. The sarcolemmal Na+ + K+-ATPase activity was decreased and the non-specific phosphatase activity was increased at early, moderate and late stages of heart failure. 4. The sarcolemmal Ca2+-ATPase activity was decreased at moderate and late stages whereas the Mg2+-ATPase activity was decreased at the late stages of heart failure only. 5. A marked decrease was found in calcium binding by heart sarcolemma from cardiomyopathic hamsters at late stages of failure. 6. These results suggest that dramatic sarcolemmal changes are associated with heart failure, and support the view that membrane abnormalities play a crucial role in the development of myocardial dysfunction, cyclase, calcium binding, heart failure, heart membranes, sarcolemmal enzymes.
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PMID:Comparison of heart sarcolemmal enzyme activities in normal and cardiomyopathic (UM-X7.1) hamsters. 13 61

1. The interaction of a variety of fluorescent probes with the membranes of adrenal medullary chromaffin granules is described. 2. Changes in the motional properties of the bound probes with temperature were investigated and evidence is presented which indicates that ordering of the membrane lipids occurs below 33 degrees C. 3. The ordering is characteristics of the membrane lipids and is retained by sonicated aqueous dispersions of the total lipid extracted from chromaffin granule membranes. 4. The ATPase and NADH:acceptor oxidoreductase activities of the chromaffin granule membrane have discontinuous Arrhenius temperature versus activity relationships with 'transitions' at 33 degrees C. 5. The ATPase has a second transition at 36.5 degrees C. 6. The 33 degrees C 'transition' for the NADH:acceptor oxidoreductase is removed by treatment with the detergent Triton X-100. 7. The correlation between the onset of lipid ordering and the change in activation energy of the membrane-bound enzyme activities is discussed in terms of the co-operative interactions of the different membrane components. The possible role of lipid ordering in exocytosis is discussed.
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PMID:Lipid ordering and enzymic activities in chromaffin granule membranes. 13 88

1. A stable membrane-bound ATPase [EC 3.6.1.3] (TF0-F1) capable of proton translocation in reconstituted vesicles was purified from the thermophilic bacterium PS3 cultured in medium containing L-[U-14C]amino acids. 2. TF0-F1 was composed of a catalytic moiety (TF1) and a hydrophobic moiety (TF0). TF1 contained 3 polypeptide chains with molecular weights of 56,000, 3 of 53,000, 1 of 32,000, 1 of 15,500, and 1 of 11,000. TF0 contained 1 chain of 19,000, 2 of 13,500, and 5 of 5,400 daltons. TF1 was dissociated into subunits much less readily than F1. 3. TF1 consisted of 95A particles arrayed in hexagonal microcrystals. TF0-F1 consisted of a sphere (TF1) and a stalk plus base (TF0) which was buried in the membrane of the proton translocating vesicles. 4. Vesicles capable of energy transformation were formed when TF1 came in contact with the surface of liposomes containing TF0. On addition of phospholipids, the helix content of TF0 increased 3-fold. The role of F0 in forming channels for protons is discussed. 5. The amino acid compositions of TF0, TF1, and TF0-F1 were compared. TF0 was not hydrophobic, despite its interaction with phospholipids. The phospholipid composition and other properties of the proton translocating vesicles were examined. Vesicles reconstituted from a mixture of phosphatidylethanolamine, phosphatidylgly-cerol, and cardiolipin in the same ratio as in the membranes had the highest activity.
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PMID:Proton translocating ATPase of a thermophilic bacterium. Morphology, subunits, and chemical composition. 13 94

The influence of cholesterol on the membrane-bound acetylcholinesterase and (Ca2+ + Mg2+)-ATPase was studied in erythrocytes of five groups of male rats fed different fat-supplemented diets. Two groups of rats were fed essential fatty acid (EFA) sufficient diets with 5% lard or corn oil as the dietary fat, and two groups were fed EFA-deficient diets: a basic, fat-free diet and the same diet supplemented with 5% hydrogenated beef fat. One additional group of rats was fed a stock diet. The kinetic changes recorded were in the degree of the cooperativity of the inhibition by F- of the acetylcholinesterase and the activation by Ca2+, and by Mg2+ of the (Ca2+ + Mg2+)-ATPase. The kinetic behavior of the enzymes was only modified by cholesterol feeding when they were bound to a membrane with a high fatty acid fluidity (e.g. derived from rats fed the corn oil-supplemented diet). The enzymes from a membrane with a low fatty acid fluidity (e.g. derived from rats fed a lard-supplemented diet) were not altered by cholesterol feeding. The changes were noticeable after 24 hours of cholesterol feeding. It is suggested that the in vivo cholesterol sites are involved in a regulatory mechanism for mammalian membrane-bound enzymes.
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PMID:Kinetic modifications of the acetylcholinesterase and (Ca2+ + Mg2+)-ATPase in rat erythrocytes by cholesterol feeding. 13 2

1. Modification of a single amino acid residue by introduction of the nitrobenzofurazan group inactivates mitochondrial ATPase (adenosine triphosphatase) when membrane-bound in submitochondrial particles. The similarity between the reactions of both membrane-bound and isolated ATPase with 4-chloro-7-nitrobenzofurazan indicates that the single essential tryosine residue identified in the isolated enzyme [Ferguson, Loyd, Lyons & Radda (1975) Eur. J. Biochem. 54, 117-126] Is also a feature of the membrane-bound ATPase. 2. A procedure is presented for estimating the ATPase content of the inner mitochondrial membrane. It is based on the specificity of the incorporation of the nitrobenzofurazan group, and the ready removal of this group by compounds that contain a thiol group. This method indicates that 8.5% of the membrane protein is ATPase. The procedure should be applicable to the titration of the energy-transducing ATPases of bacterial plasma membranes and of the thylakoid membranes of chloroplasts. 3. Combination of the data obtained on the ATPase content of the bovine heart inner mitochondrial membrane with a titration of the cytochrome bc1 complex with antimycin indicates that these two components of the membrane are present in approximately equal amounts.
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PMID:A method for determining the adenosine triphosphatase content of energy-transducing membranes. reaction of 4-chloro-7-nitrobenzofurazan with the adenosine triphosphatase of bovine heart submitochondrial particles. 13 62

Calcium binding at 0 degrees C to a purified sheep kidney Na+,K+-ATPase was described by linear Scatchard plots. Binding at saturating free calcium was 65-80 nmol/mg of protein, or 30-40 mol of calcium/mol of enzyme. Aqueous emulsions of lipids extracted from Na+,K+-ATPase yielded dissociation constants and maximum calcium-binding values that were similar to those for native Na+,K+-ATPase. Phospholipase A treatment markedly reduced calcium binding. Pretreatment of native Na+,K+-ATPase with ouabain increased the dissociation constant for calcium binding from 131 +/- 7 to 192 +/- 7 muM without altering maximum calcium binding. Ouabain pretreatment did not affect calcium binding to extracted phospholipids, ouabain-insensitive ATPases, or heat denatured Na+,K+-ATPase, Na+ and K+ (5-20 mM) increased the dissociation constants for calcium, which suggests competition between the monovalent cations and calcium for the binding sites. At higher concentrations of monovalent cations, ouabain increased the apparent affinity of binding sites for calcium. Extrapolation to physiological cation concentrations revealed that the ouabain-induced increase in apparent affinity for calcium may be as much as 2- to 3-fold. These results suggest: (1) calcium binds to phospholipids associated with Na+,K+-ATPase; (2) ouabain interaction with Na+,K+-ATPase induces a perturbation that is transmitted to adjacent phospholipids, altering their affinity for calcium; and (3) at physiological concentrations of Na+ or K+, or both, ouabain interaction with Na+,K+-ATPase may lead to an increased pool of membrane-bound calcium.
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PMID:A possible molecular mechanism of the action of digitalis: ouabain action on calcium binding to sites associated with a purified sodium-potassium-activated adenosine triphosphatase from kidney. 13 87

Previous studies have shown that mutations in the unc gene of Escherichia coli K12 cause defects in energy transduction as well as a membrane-bound (Mg2+, Ca2+)-adenosine triphosphatase. We studied the effect of this mutation on the "downhill" efflux of methyl-beta-D-galactopyranoside, a suboli K12 did not show significant differences in substrate influx of efflux, a differential effect of an uncoupler, 2,4-dinitrophenol was demonstrated. In contrast to the unc+, dinitrophenol failed to inhibit significantly the rate coefficient of efflux in the unc- strain. Analysis of spontaneous unc+ revertants of the unc- mutant provided additional evidence that a functional unc gene is necessary for dinitrophenol inhibition of efflux. Other uncouplers tested in the unc+ strain showed different effects on efflux. While arsenate, azide and carbonyl cyanide p-trifluoromethoxyphenulhydrazone caused little or no effect, 2,4-dibromophenol and pentachlorophenol increased efflux by a considerable factor.
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PMID:Effect of uncoupler on "downhill" substrate efflux of Escherichia coli is dependent on (Mg2+, Ca2+). Adenosine triphosphatase. 13 4

The action of atebrin on purified adenosine triphosphatase (ATPase) from Micrococcus lysodeikticus was studied as well as on the membrane-bound and soluble ATPases from Escherichia coli and Bacillus megaterium. Atebrin inhibited the Ca(2+)-dependent activity of all these enzymes, and the inhibition was reversed by an excess of Ca(2+) ions. Kinetic studies carried out with the purified enzyme from M. lysodeikticus showed that the inhibition by atebrin was strongly cooperative, suggesting the complex nature of the process. On the other hand, atebrin stimulated the Mg(2+)ATPase activity of the M. lysodeikticus enzyme, displacing its adenosine 5'-triphosphate (ATP)/Mg(2+) optimum ratios, but inhibited the Mg(2+)-ATPase activity of E. coli provided that ATP was in excess over Mg(2+), i.e., that the ATP/Mg(2+) ratio was higher than its optimum. These results suggest that divalent cations influence the bacterial ATPases in different ways depending on the type of divalent ion and/or enzyme. The effect of atebrin on bacterial ATPases may reflect those differences, and its complex mechanism of action might be related to the existence of more than one site for divalent cations and/or distinct conformational states in these enzymes.
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PMID:The effect of atebrin on bacterial membrane adenosine triphosphatases in relation to the divalent cation used as substrate and/or activator. 13 84


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