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 ATPase activity of chicken gizzard myosin was studied by varying the KCl concentration in the reaction medium. The following was thus found: (a) A sharp depression of the activity occurred when the KCl concentration was reduced to less than 0.3 M, showing the minimum activity around 0.15 M KCl. (b) The activity depression was removed by addition of urea or bay papain-digestion, but not by addition of p-chloromercuribenzoate. (c) In the KCl concentration where the activity depression occurred, the ATPase reaction proceeded in two distinct phases; the activity was relatively high in the early phase of the reaction and declined into the later phase where the steady state reaction took place. (d) In the KCl concentrations higher than that particular concentration or in the presence of urea, the ATPase reaction proceeded in one phase. (e) The temperature dependence of the ATPase activity in the early phase was of an ordinary magnitude being approximately equal to that of the ATPase activity in 0.6 M KCl. In contrast, the temperature dependence of the activity in the later phase was unusually small. Gizzard myosin in various concentrations of KCl was also examined by measuring the turbidity and the light-scattering intensity, and by observation under an electron microscope. The following was thus found: (a) In the KCl concentration where the activity depression occurred, there was a stagnation in the turbidity decrease as the KCl concentration was gradually increased and also the formation of "thick filaments," each of which was approximately 0.6-0.9 micron in length and 20-30 nm in diameter with no central "bare zone." (b) Addition of ATP induced dissociation of the thick filaments, and the dissociation occurred during the early phase of the ATPaseeaction. (c) Moreover, the temperature dependence of the ATP-induced dissociation rate was approximately equal to that of the ATPase activity in the early phase. On the basis of the findings mentioned above, it is concluded that the activity depression results from the ATP-induced dissociation of myosin filaments. Moreover, since high concentrations of KCl or urea also caused dissociation of myosin filaments and yet did not produce the activity depression, it was strongly suggested that gizzard myosin in the ATP-dissociated form must be different from that in the urea- or KCl-dissociated form, probably in the physical state of some myosin aggregates which were not detectable by the physical methods we used. As a side-observation, gizzard myosin filaments formed in the presence of ADP were found to be unusually long (longer than 2 micron), and they looked very similar to the particular filaments of skeletal myosin that were reported, by Moos, to be formed in the absence of the C protein.
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PMID:Adenosine triphosphatase activity and "thick filament" formation of chicken gizzard myosin in low salt media. 14 68

The membrane ATPase (EC 3.6.1.3) of Bacillus subtilis can be solubilized by a shock-wash process. Two procedures for purifying the solubilized enzyme are reported. A protease inhibitor, phenylmethane sulfonylfluoride, was introduced in the solubilization and purification step. The resultant ATPase purified by density gradient centrifugation has a molecular weight of 315 000, an s20,w of 13,4 and an amino acid composition very similar to bacterial ATPases already studied. After exposure to polyacrylamide gel electrophoresis in presence of sodium dodecyl sulphate (SDS), or 8 M urea or SDS-urea, the purified ATPase can be dissociated in two non-identical subunits of molecular weights 59 000 (alpha) and 57 000 (beta) with different charges. Kinetic studies showed that Ca2+ or Zn2+ are required for ATPase activity, although Mg2+ was uneffective. At optimal Ca2+ concentration, the Mg2+ has an inhibitory effect. The Km for ATP is 1.3 mM. Inhibitors of the oxydative phosphorylation, of the mitochondrial ATPase and of the (Na+ + K+)-ATPase are studied.
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PMID:Membrane ATPase of Bacillus subtilis. I. Purification and properties. 14 10

A) The proximal nephron and perinatal regulation of extracellular volume. 1. The glomerular capillary permeability coefficient (Kf) changes mainly because of an increasing capillary hydraulic conductance (Lp) within the autoregulatory range of renal perfusion pressure. 2. Proximal tubule hydrostatic hydraulic conductance and response to transmural protein concentration gradients is high during perinatal adaptation. 3. Proximal tubule paracellular shunt pathways are more important for absorption during differentiation than at maturity. 4. Basolateral membrane area of the single epithelial segment (10(-6) micron2 mm-1) increases and the typical basal labyrinth architecture develops. 5. The activity of the transport enzyme Na-K-ATPase increases in parallel to the basolateral membrane area to result in a constant number of enzyme sites during normal ontogeny. B) The distal nephron and perinatal regulation of extracellular osmotic activity. 6. Inner medullary urea content increases at osmotic equilibrium between interstitium and collecting duct. 7. The loop of Henle gradually dilutes the isotonic luminal fluid in the course of perinatal differentiation. 8. The thick ascending segment of the loop of Henle differentiates its anisotonic transport by increasing the Na-Chloride transport at constant hydraulic conductivity. 9. Ultrastructure and N-A-K-ATPase activity of the diluting segment (TAL) change greatly during ontogeny. 10. The centrifugal pattern of renal maturation from the juxtamedullary towards the superficial cortical layers leads to an intracortical profile of structure and function.
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PMID:Nephron function and perinatal homeostasis. 15 Feb 48

The H+-translocating ATPase complex from the thermophilic bacterium PS3 (TF0-F1) is composed of a water-soluble part with ATP-hydrolyzing activity (TF1) and a membrane moiety with H+-conducting activity (TF0). TF0 was obtained by treating TF0-F1 with urea and removing contaminations on a carboxymethyl-cellulose column. This TF0 contained only two kinds of subunits, band 6 protein (13,500 daltons) and band 8 protein (5400 daltons), and it was active in H+ conduction and TF1 binding when reconstituted into proteoliposomes (TF0 vesicles). The binding of TF1 to TF0 present in vesicles restored energy-transducing activities, such as ATP-32Pi exchange, dicyclohexylcarbodiimide-sensitive ATPase, and ATP-dependent enhancement of 8-anilinonaphthalene-1-sulfonate fluorescence. Treatments such as protease digestion and chemical modification with acetic anhydride, succinic anhydride, or diazobenzenesulfonic acid destroyed the TF1-binding activity, which was caused by band 6 protein. Band 8 protein was a proteolipid that reacted specifically with dicylcohexyl-carbodiimide and seemed to play a central role in H+ conduction through the membrane.
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PMID:Resolution of the membrane moiety of the H+-ATPase complex into two kinds of subunits. 15 64

A method was developed to obtain a preparation of chicken gizzard heavy meromyosin (HMM) that retains the two light-chain components of parent myosin: the 20,000-dalton and 17,000-dalton light-chains. The HMM preparation was also shown to retain two characteristics of the ATPase activity of the parent myosin: the characteristic effect of phosphorylation of the 20,000-dalton light-chain component on the ATPase activity, and the characteristic dependence of the ATPase activity on the KCl concentration. 1. Two distinct stages were observed in the Mg-ATPase reaction catalyzed by gizzard HMM and rabbit skeletal actin in the presence of gizzard "native" tropomyosin (NTM) and Ca2+ ions: an early lag phase, in which the reaction rate gradually increased, and a subsequent steady state, in which the reaction proceeded at a high, constant rate. Urea-gel electrophoresis revealed that the 20,000-dalton light-chain component was gradually phosphorylated in the lag phase, and was fully phosphorylated in the steady state. It was also observed that addition of EGTA (to remove Ca2+ ions) at various times in the lag phase caused neither a further increase nor a decrease in the reaction rate, and that addition of EGTA in the steady state caused no change in the reaction rate. These observations imply that the ATPase activity increased as the amount of phosphorylated 20,000-dalton light-chain component increased, and also that Mg-ATPase of acto-phosphorylated HMM was no longer calcium-sensitive. 2. The Mg-ATPase activity of HMM in the presence of gizzard NTM and Ca2+ ions or EGTA was studied as a function of the concentration of rabbit skeletal actin. The maximal activity (Vmax) and the apparent affinity constant of acto-HMM (KA) were thus estimated from the double-reciprocal plot of Eisenberg-Moos: the Vmax and KA values for phosphorylated HMM (in the presence of Ca2+ ions) were 5 S(-1) and 5.5 mg/ml actin, respectively, and the Vmax value for unphosphorylated HMM (in the presence of EGTA) was 0.3 S(-1), assuming that the KA value with unphosphorylated HMM is equal to that with phosphorylated HMM.
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PMID:Chicken gizzard heavy meromyosin that retains the two light-chain components, including a phosphorylatable one. 15 13

1. A troponin C-like protein was prepared from frozen chicken gizzard by preparative polyacrylamide gel electrophoresis and its apparent molecular weight was estimated to be about 15,500 daltons. 2. In urea gel electrophoresis, the mobility of the troponin C-like protein increased slightly in the presence of Ca2+, like that of skeletal muscle troponin C. On the other hand, the mobility of the the troponin C-like protein in glycerol gel electrophoresis, unlike that of skeletal muscle troponin C, was significantly decreased by Ca2+. 3. In alkaline gel electrophoresis, the troponin C-like protein formed a Ca2+-dependent complex with troponin I or troponin T from skeletal muscle. 4. The troponin C-like protein could neutralize the inhibitory effect of skeletal muscle troponin I on the Mg2+-activated ATPase of actomyosin from rabbit skeletal muscle, but could not confer Ca2+-sensitivity on the actomyosin in the presence of troponin I and troponin T from skeletal muscle.
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PMID:Troponin C-like protein in chicken gizzard muscle. 15 22

1. Extracts of several plant species contained nucleoside-AMP phosphotransferase activity. The ratio of activity with thymidine to that with uridine as nucleoside substrate was essentially constant, both between species and throughout plant development. Evidence is presented that the total thymidine-AMP phosphotransferase activity of the leaves of Asplenium nidus (bird's-nest fern) and of Helianthus tuberosus (Jerusalem artichoke) increases during maturation. 2. Thymidine-AMP phosphotransferase was purified 22-fold from a very rich source of this activity, extracts of A. nidus. 3. A broad specificity towards both nucleoside and nucleoside 5'-monophosphate substrates is displayed by this preparation, and the evidence suggests that all could be due to a single enzyme. 4. Nucleosides that act as substrates will also inhibit phosphotransfer to other nucleosides, with Ki values close to the corresponding Km values found when utilized as substrates. 5. Ca2+-activated ATP phosphohydrolase was separated from the phosphotransferase by differential complexing to Blue Dextran in the presence of urea, whereas an AMP phosphohydrolase activity was closely associated with thymidine-AMP phosphotransferase through all separation techniques used. 6. Metal ions did not activate either of the latter two activities, and 1,10-phenanthroline was found to inhibit the phosphotransferase. 7. Km values for AMP for the respective activities were 0.11 mM (thymidine phosphotransferase) and 0.20 mM (AMP phosphohydrolase) and for thymidine (phosphotransferase only) 0.88 mM. 8. 3':5'-Cyclic AMP was found to inhibit both phosphotransferase and AMP phosphohydrolase activities, with Ki values of 0.056 mM and 0.15 mM respectively. It is suggested that this inhibitor would be of value in revealing the existence of thymidine kinase in plant extracts with high thymidine phosphotransferase activity.
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PMID:Thymidine phosphotransferase and nucleotide phosphohydrolase of the fern Asplenium nidus. General properties and inhibition by adenosine 3':5'-cyclic monophosphate. 18 31

A carrier protein mediating alanine transport was purified from the membranes of the thermophilic bacterium PS3, by ion exchange chromatography in the presence of both Triton X-100 and urea. The alanine carrier was recovered in the nonadsorbed fraction from either DEAE- or CM-cellulose columns, suggesting that its isoelectric point was in the neutral pH region. The final preparation contained virtually no electron transfer components, ATPase, or NADH dehydrogenase. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that the final preparation consisted of two major protein components with molecular weights of 36,000 and 9,400. Active transport of alanine after incorporation of the alanine carrier into reconstituted proteoliposomes was driven not only by an artificial membrane potential generated by potassium ion diffusion via valinomycin but also by mitochondrial cytochrome oxidase incorporated into the same liposomes and supplemented with both cytochrome c and ascorbic acid. The membrane-integrated portion (TFo) of the ATPase complex uncoupled alanine transport by conducting protons across the membrane.
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PMID:Isolation of the alanine carrier from the membranes of a thermophilic bacterium and its reconstitution into vesicles capable of transport. 19 18

Troponin inhibitory factor, TNI, was prepared by affinity chromatography from different mammalian hearts. (i) Structure. These different TNI have the same M.W. (28000), which is higher than that found in rabbit skeletal muscle (23000). Nevertheless they differ with respect of their charge as shown by alkaline urea polyacrylamide gel electrophoresis using cardiac TNI which has previously been bound to an excess of skeletal troponin Ca2+-binding factor. These changes do not correlate with the PO4 content of TNI. They are associated with structural differences demonstrated by peptide mapping of the unfolded molecule after papain treatment. The structure of cardiac TNI from rat and rabbit differs clearly from that of crow and pig. (ii) Biological activity. These different TNI have the same inhibitory effect on skeletal actomyosin. ATPase, the same content of PO4 and the same ability to be phosphorylated in-vitro by a bovine heart c-AMP-dependent protein kinase.
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PMID:A comparative study of the cardiac troponin inhibitory factor (TNI) from mammalians. 20 99

1. A highly stable ATPase (TF1) was purified to a monodispersed state from the membranes of a thermophilic bacterium PS3. Its molecular weight was 380,000, and it was composed of five subunits alpha, beta, gamma, sigma', and sigma with molecular weights of 56,000, 53,000, 32,000, 15,500, and 11,000, respectively. 2. TF1 was stable against dissociating agents such as 5.5 M urea and 4.0 M LiCl, organic solvents, such as 60% acetone, heavy metals, and detergents. Low concentrations of all these agents stimulated its activity at 60 degrees. 3. TF1 was not cold-labile and showed a maximal activity at 70 degrees. Its CD spectrum revealed that its conformation changed between 81 and 96 degrees, and that its contents of alpha helices and beta structures were 27.3 and 12.8%, respectively, at 75 degrees. 4. TF1 was completely dissociated by treatment with dodecyl sulfate at 60 degrees and then with 7.1 M urea. The dissociated TF1 was reconstituted by treatment with Dowex 1-X2, and then dialysis. 5. [3H]Acetyl-TF1 bound to TF1-depleted membranes. TF1 only catalyzed 32Pi-ATP exchange and showed sensitivity to inhibitors of energy transfer when bound to the membranes. 6. A hydrophobic membrance component (TFo) was isolated which rendered TF1 sensitive to inhibitors of energy transfer. It was composed of three subunits (with molecular weights of 19,000, 13,500, and 5,400) and P-lipids.
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PMID:A highly stable adenosine triphosphatase from a thermophillie bacterium. Purification, properties, and reconstitution. 24 Aug 42


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