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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 pH-activity curve of heavy meromyosin ATPase [EC 3.6.1.3] was measured at various temperatures. The pH-activity curve at higher temperatures showed a maximum at low pH and a minimum at pH 7 to 8 as has been already reported. At lower temperatures it was sigmoidal in shape, similar to a simple dissociation curve of pKa 6 to 7. The pH-activity curve at intermediate temperatures appeared to be inbetween the two extreme shapes. These changes in pH-activity curve with temperature were found to be common in the presence of divalent cations such as Mg2+, Mn2+, and Ca2+. The ATPase mechanism may be identical in the presence of any divalent cation, and the rate determining step revealing the steady state rate alters by changing the temperature. The transition temperatures estimated at pH 8 were 10 degrees, 8 degrees, and about 5 degrees in the presence of MnCl2, CaCl2, and MgCl2, respectively. The difference in the temperature coefficients above and below the transition temperature was most distinct in the presence of MnCl2, and vague in the presence of CaCl2. A similar change of pH-activity curve with temperature was found with heavy meromyosin ITPase in the presence of MgCl2.
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PMID:Temperature induced transition of the pH-activity curve of heavy meromyosin adenosine triphosphatase and inosine triphosphatase. 1 40

The UV absorption difference spectrum of heavy meromyosin induced by ATP was measured at various temperatures. At higher temperatures, the difference spectrum formed rapidly after adding ATP and continued steadily during the steady state which we have called the ATP-form of difference spectrum. At lower temperatures, the ATP-form of difference spectrum decayed into the other form before the steady state was attained. This was identical to the difference spectrum obtained by adding ADP and has been called the ADP-form of difference spectrum. At intermediate temperatures, biphasic decay was observed. The results indicate that the dominant intermediate at the steady state is altered from the one showing the ATP-form of difference spectrum at higher temperatures to that showing the ADP-form at lower temperatures. The population of the two intermediates depends on the temperature between the two extremes. This temperature-induced transition was observed in the presence of any divalent cation such as Mg2+, Mn2+, or Ca2+. A similar transition was observed with the difference spectrum induced by ITP in the presence of MgCl2. The pH dependence of the single early decay of the ATP-induced difference spectrum was measured in the presence of MnCl2 at 1 degree. The apparent rate constant of the decay showed a biphasic pH dependence, having the same shape as the pH activity curve of ATPase [EC 3.6.1.3] observed at higher temperatures. The rate determining step for the steady state ATPase at higher temperatures is thought to be the step of changing from the intermediate complex showing the ATP-form of difference spectrum to that showing the ADP-form. This is inconsistent with our previous mechanism (Yazawa, M. et al. (1973) J. Biochem. 74, 1107-1117). The rate determining step at lower temperatures was assigned as a step of ADP dissociation.
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PMID:Temperature dependence of the decay of the UV absorption difference spectrum of heavy meromyosin induced by adenosine triphosphate and inosine triphosphate. 1 41

(Na+K)-activated ATPase activity from gills of yearling spring chinook was examined using a new rapid assay method. Characterization of the enzyme activity was performed. Optimal activity was obtained at pH 7.2 in the presence of 240 mM NaCl, 120 mM KCl, 20 mM MgCl2 and 10 mM Na2ATP. Maximal inhibition of the enzyme was observed in the presence of 0.5 mM ouabain. Differential centrifugation indicated that 75% of the enzymatic activity was sedimented at 1000 x g. Only 8% of the activity was found in the microsomal pellet. Treatment with 0.1% sodium deoxycholate liberated activity from the 1000 x g pellet and elevated the activity. This treatment caused a loss of 20% of the original activity of the preparation. Statistical analysis of the sampling procedure for gill (Na+K)-activated ATPase activity indicated that there was small variation in the technique itself when compared to variation between the individual gill arches and between individual fish. Results indicate that for meaningful comparisons of groups of fish, the sampling of the gill arches must be standardized and a large number of individual fish must be sampled.
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PMID:Characterization of gill (Na + K)-activated adenosine triphosphatase from chinook salmon, Oncorhynchus tshawytscha. 1 43

Myosin from rabbit stomach was highly purified by ammonium sulfate fractionation in the presence of ATP and MgCl2, ultracentrifugation and Sepharose 4B chromatography. The myosin composed of one heavy and two light chains as determined by SDS-gel electrophoresis. The molecular weights of the light chains were the same as those of gizzard myosin, about 20,000 and 17,000, respectively. The pH-activity curve and the KCl concentration dependency of Ca-ATPase of the stomach myosin were similar to those of other smooth muscle myosins. The stomach myosin was more resistant to pepsin digestion than skeletal myosin. Other proteolytic enzymes, trypsin, chymotrypsin, papain, and nagarse, digested the myosin in the same way as skeletal myosin.
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PMID:Purification and some properties of rabbit stomach myosin. 1 37

The ATPase (EC 3.6.1.3) activity of 30 S dynein from Tetrahymena cilia was remarkably stimulated by porcine brain tubulin at pH 10. The activity increased with increasing concentration of tubulin until the molar ratio of tubulin dimer to 30 S dynein reached approx. 10. The optimum of the ATPase activity of 30 S dynein in the presence of tubulin was 1-2 mM for MgCl2 and 2 mM for CaCl2. Increasing ionic strength gradually inhibited the stimulation effects of tubulin. Activation energies of 30 S dynein in the presence and absence of tubulin were almost the same. At the temperatures beyond 25 degrees C stimulation effects of tubulin disappeared. ATP was a specific substrate even in the presence of tubulin. In kinetic investigations parallel reciprocal plots were observed in a constant ratio of divalent cations to ATP of 2, indicating that tubulin was less tightly bound to 30 S dynein in the presence of ATP than the absence. The similar results were obtained at pH 8.2. 14 S dynein and the 12 S fragment which have poor ability to recombine with outer fibers were also activated with brain tubulin.
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PMID:Interactions of Tetrahymena dynein with microtubule protein. Tubulin-induced stimulation of dynein ATPase activity. 2 Sep 50

1. ATPase isolated from Rhodospirillum rubrum by chloroform extraction and purified by gel filtration or affinity chromatography shows three bands (alpha, beta and gamma) upon electrophoresis in sodium dodecyl sulphate. 2. Ca2+-ATPase activity of the preparation is inhibited by aurovertin and efrapeptin but not by oligomycin. Activity may be inhibited by treatment with 4-chloro-7-nitrobenzofurazan and subsequently restored by dithiothreitol. 3. The enzyme fails to reconstitute photophosphorylation in chromatophores depleted of ATPase by sonic irradiation. 4. Most of the active protein from the crude chloroform extract binds to an affinity chromatography column bearing an immobilised ADP analogue but not to a column bearing immobilised pyrophosphate. 5. In the absence of divalent cations, a component with a very high specific activity for Ca2+-ATPase is eluted from the column by 1.6 mM ATP. This protein migrates asa single band on 5% polyacrylamide gel electrophoresis and only possesses three subunits. At 12 mM ATP an inactive protein is eluted which does not run on acid or alkali polyacrylamide gels and shows a complex subunit structure. 6. ATPase preparations prepared by acetone extraction or by sonic irradiation of chromatophores may also be purified 10-fold by affinity chromatography. 7. The inclusion of 5 mM MgCl2 or CaCl2 during affinity chromatography of chloroform ATPase increases the capacity of the column for the enzyme and demands a higher eluting concentration of ATP. 8. When the enzyme is more than 90% inhibited by efrapeptin or 4-chloro-7-nitrobenzofurazan, the binding characteristics of the enzyme are not affected. 9. 10 mM Na2SO3, which greatly stimulates the Ca2+- and Mg2+-dependent ATPase activity of the enzyme and increases Ki (ADP) for Ca2+-ATPase from 50 to 850 micron, prevents binding to the affinity column. Binding may be restored by the addition of divalent cations. 10. Na2SO3 increases the rate of ATP hydrolysis, ATP-driven H+ translocation and ATP-driven transhydrogenase in chromatophores. 11. It is proposed that anions such as sulphite convert the chromatophore ATPase into a form which is a more efficient energy transducer.
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PMID:Affinity chromatography of H+-translocating adenosine triphosphatase isolated by chloroform extraction of Rhodospirillum rubrum chromatophores. Modification of binding affinity by divalent cations and activating anions. 2 12

1. (Na+ +K+)-dependent ATPase was partially purified from eel gills by a procedure in which the microsomal fraction of crude preparations of chloride cells was selectively extracted with sodium dodecyl sulphate. 2. The microsomal specific activity was increased 2-fold during optimal treatment with detergent. 3. The final preparation (56% pure) had a specific activity of 341 mumol of ATP hydrolysed/h per mg of protein and a turnover number of 3560 min-1. The number of ouabain-binding sties equalled the number of sites phosphorylated by ATP. 4. Both sodium orthovanadate and ouabain inhibited the purified preparation more than the microsomal fraction, vanadate being more effective on an equimolar basis than ouabain. 5. Inhibition by orthovanadate was not enhanced at 28 mM-as compared with 1mM-MgCl2 and was not reversed by beta-adrenergic agonists (cf. Josephson & Cantley (1977) Biochemistry 16, 4572--4578). 6. Of various other metallic oxyanions tested only niobate proved an effective inhibitor of the enzyme although this anion was less effective than orthovanadate. 7. Orthovanadate partially inhibited phosphorylation of the enzyme by ATP in the presence of 28 mM-MgCl2.
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PMID:The partial purification of sodium-plus-potassium ion-dependent adenosine triphosphatase from the gills of Anguilla anguilla and its inhibition by orthovanadate. 3 42

(1) F0.F1ATPase (EC 3.6.1.3) from Micrococcus luteus ATCC 4698 was solubilized from plasma membranes by the non-ionic detergent Triton X-100 in the presence of 0.05 M MgCl2. (2) The antibiotics rutamycin, Dio-9, quercetin, oligomycin, botrycidin, efrapeptin, leucinostatin, valinomycin, and venturicidin as well as N,N'-dicyclohexylcarbodiimide and dinitrophenol are potent inhibitors of F0.F1ATPase activity.(3) F0.F1ATPase activity is completely inhibited by anti-F1ATPase antibodies. The inhibition is non-competitive. (4) Crossed immunoelectrophoresis reveals a reaction of immunological identity of F0.F1ATPase and F1ATPase indicating that both enzymes have in common antigenic sites.
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PMID:Immunological properties of membrane-bound adenosine triphosphatase: immunological identification of rutamycin-sensitive F0.F1ATPase from Micrococcus luteus ATCC 4698 established by crossed immunoelectrophoresis. 7 81

The DNA polymerase of early embryos of Drosophila melanogaster has been purified to near-homogeneity. The purified enzyme gave a single, catalytically active protein band after polyacrylamide gel electrophoresis, under nondenaturing conditions. Four polypeptides with molecular weights 43,000, 46,000, 58,000, and 148,000 were resolved when this band was electrophoresed under denaturing conditions. At high ionic strengths, the DNA polymerase had a sedimentation coefficient of 8.7 S, a Stokes radius of 78 A and frictional ratio of 1.81, parameters that yield a molecular weight of 280,000. The purified DNA polymerase possessed no detectable endo- or exodeoxyribonuclease, ATPase, or RNA polymerase activity. Using an "activated" DNA template-primer, the enzyme had a pH optimum of 8.5. It was stimulated by (NH4)2SO4, KCl, and to a lesser extent, NaCl. A divalent metal cation was absolutely required; MgCl2 stimulating activity 7-fold more than MnCl2. It was inhibited by low concentrations of N-ethylmaleimide and Aphidicolon. Thus the DNA polymerase of D. melanogaster resembles most closely the alpha-DNA polymerases that have been purified from mammalian cells.
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PMID:A high molecular weight DNA polymerase from Drosophila melanogaster embryos. Purification, structure, and partial characterization. 11 15

Rabbit cardiac myosin, isolated from frozen tissue, was effectively purified by batchwise treatment with DEAE-cellulose in addition to suing cilution-precipitation techniques. An extensive experimental program was subsequently carried out with respect to the enzymic amino acid, optical and physicochemical properties of native cardiac myosin. This program has included the following: examination of the effects of pH and varying concentrations of ATP, CaCl2, MgCl2, and PCMB on its ATPase activity; measurement of its circular dichroic spectrum in solvent buffers, at different pH or containing ATP in the absence or presence of Ca-2+ or Mg-2+ ions; study of the concentration dependence of its viscosity and sedimentation velocity at low temperatures; and investigation of its molecular weight by the Archibald method and low- and high-speed sedimentation equilibrium. The results of these studies were consistent with the interpretation that cardiac myosin is comprised of highly asymmetric, semi-rigid molecules with a molecular weight in the order of 4.7 times 10-5, which display non-ideality even in solvent buffers of high ionic strength at neurtal pH. In addition, computer analysis of the high-speed sedimentation equilibrium data has provided evidence for the presence of a self-association reaction at low protein concentration. Even though the specif ATPase activity of cardiac myosin was found to be approximately one-third that reported for skeletal myosin in all cases, it was concluded, on the the basis of the essentially analogous physical and chemical properties of rabbit cardiac and skeletal myosin, that the two proteins are very similar in terms of molecular size, shape, and secondary structure.
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PMID:Rabbit cardiac myosin. I. Physical and chemical characterization of the native molecule. 12 22


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