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)

It has been shown that soluble ATPase from chloroplasts adsorbed at the octane/water interface generates an ATP hydrolysis coupled potential charge (deltapi) at the interphase. This process occurs in the presence of a lipid-soluble proton acceptor, in the capacity of which 2,4-dinitrophenol is used. The dependence of deltapi, generated by ATPase, on the concentration of the enzyme. ATP and dinitrophenol, has been studied.
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PMID:[Proton transfer from water to octane coupled with the reaction of ATP hydrolysis by soluble ATPase from chloroplasts]. 13 85

Oriented immobilized F-actin (IA) threads were prepared by extrusion of the concentrated F-actin solutions through a capillar into an aceton-water mixture containing glutaraldehyde. Myosin ATP-ase activity was activated by IA in the presence of Mg+2 and inhibited in the presence of EDTA. ATPase activity of IA at high temperature (55) was about 0.054 min(-1) and was not affected by a deformation of threads. Mechanical properties of IA threads were changed when treated by reagnets influencing intra- and inter-molecular interactions of actin molecules, and these changes themselves were highly dependent on IA threads deformation.
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PMID:[Mechanochemical interactions in enzymes. IV. Mechanochemical properties of immobilized preparations of F-actin]. 13 84

The effects of D2O on the elementary steps in the contractile and transport ATPase [EC 3.6.1.3] reactions were studied, and the following results were obtained: 1. The rate of H-meromyosin ATPase in the steady state decreased in D2O to 60% of that in H2O. Deuterium oxide did not affect the size or rate of the initial burst of Pi liberation, i.e. the amount or rate of formation of the reactive myosin-phosphate-ADP complex, MADPP. Moreover, neither the rate of change in the fluorescence spectrum of H-meromyosin induced by ATP (the rate of formation of the second enzyme-ATP complex, M2ATP) nor the rate constant of decomposition of MADPP into M degrees + ADP + Pi was affected by D2O. However, the equilibrium constant of the step M2ATP in equilibrium MADPP decreased in D2O to about 1/2 the value in H2O. 2. In the case of the Na+-K+-dependent ATPase reactin, neither the rate constant of formation of the second enzyme-ATP complex, E2ATP, nor that of decomposition of a phosphorylated intermediate, EADP approximately P, was affected by D2O. However, the equilibrium constant of the step E2ATP in equilibrium EADP approximately P decreased in D2O to about 1/2.5-1/4 of the value in H2O. These results suggest a similarity between the modes of binding of phosphate in MADPP in the myosin ATPase reaction and in EADP approximatley P in the Na+-K+-dependent ATPase reaction.
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PMID:Effects of deuterium oxide on elementary steps in the ATPase reaction. Evidence for the similarity of key intermediates in contractile and transport ATPase. 13 92

The relationship of the mucosal enzyme systems Na+-K+-activated adenosine triphophatase (Na-K-ATPase) and adenylate cyclase and their associated intestinal transport processes was studied in the rat ileum. Two ileal loops were constructed in each anesthetized rat; one loop was inoculated with saline, the other loop with choleragen. Net transport of water and electrolytes was measured in vivo after which enzyme activity was measured in the mucosa of the perfused loops. All doses of choleragen between 5 and 150 mug decreased water movement as early as 3 1/2 h after inoculation. A linear relationship between the dose of choleragen and the level of net water and electrolyte secretion was observed when choleragen doses between 5 and 150 mug were incubated in ileal loops for 4 h. Adenylate cyclase activity was always increased in secreting intestinal loops, whereas Na-K-ATPase was unaffected by choleragen. In animals pretreated with methylprednisolone acetate, 3 mg/100 g per day for 3 days before loop inoculation, saline loops had enhanced mucosal Na-K-ATPase activity had increased net water and electrolyte absorption; choleragen-exposed loops had increased adenylate cyclase and Na-K-ATPase activities, and net absorption of water and electrolytes 4 h after inoculation. These effects of methylprednisolone acetate were still present 19 1/2 h after inoculation. When a single injection of methylprednisolone acetate was given 3 1/2 h after choleragen inoculation, both adenylate cyclase and Na-K-ATPase were activated, and net intestinal absorption of water and electrolytes was observed 19 1/2 h after inoculation. These results suggest that methylprednisolone can prevent and reverse the secretory effects of choleragen by selectively stimulating a coexisting absorptive process.
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PMID:Prevention and reversal of cholera enterotoxin-induced intestinal secretion by methylprednisolone induction of Na+-K+-ATPase. 13 58

A simple centrifugation technique initially developed for fractionation of human red cells in their own plasma has been found to be readily applicable to the separation of reticulocytes normally appearing in the pig soon after birth as well as to those induced in the adult pig by phenylhydrazine administration. The density of the naturally occurring reticulocytes, maximally amounting to 10-15% of total cells derived from a 7-day-old pig, varied from 1.073 to 1.101, in contrast to the mature cells, presumed to be the fetal cell type, whose density ranged in a narrower limit, from 1.101 to 1.106. In adult animals, the reticulocytosis amounting to more than 70% takes place in response to daily administration of phenylhydrazine for 7 days. The density of these reticulocytes varied widely from 1.068 to 1.094; in contrast, the density of the mature adult red cells ranged from 1.095 to 1.106. Among various physiological parameters examined, a marked decrease in cell size, cell water content, RNA, Na+ -K+ -ATPase, and Ca2+ -ATPase activities was observed in the course of reticulocyte maturation in vivo in the adult animal. All these physiological parameters were found to undergo a similar reduction from the top to the bottom fractions of the reticulocytes separated according to their density, suggesting that the separation technique employed here represents separation of reticulocytes according to their age.
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PMID:Pig reticulocytes: II. Characterization of density-fractionated maturing reticulocytes. 13 72

Membrane vesicles isolated from wild-type and dicyclohexylcarbodiimide-resistant strains of Escherichia coli exhibit identical respiration-dependent transport activities, and in both cases, this activity is abolished by extraction of the vesicles with 1.0 M guanidine-HCl. Transport activity of extracted wild-type vesicles is completely restored by exposing the vesicles to lipophilic or water-soluble carbodiimides, while transport activity of the mutant vesicles is not restored by exposure to lipophilic carbodiimides. Strikingly, however, complete reactivation of transport in mutant vesicles is observed with water-soluble carbodiimides. Similarly, the Ca2+, Mg2+-stimulated ATPase activity of wild-type vesicles is inhibited by both classes of carbodiimides, while the ATPase activity of mutant vesicles is inhibited by water-soluble carbodiimides, but resistant to inhibition by lipophilic carbodiimides. The carbodiimide-reactive component of the membraneous Ca2+, Mg2+-stimulated ATPase complex in wildtype vesicles is readily labeled with N,N'-dicyclohexyl[14C]-carbodiimide, while the analogous component in mutant vesicles is not reactive. Alternatively, when vesicles are treated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide [14C]methiodide, a water-soluble carbodiimide, the carbodiimide-reactive component is labeled to a similar degree in both preparations. The results suggest that the altered carbodiimide-reactive proteolipid in the dicyclohexylcarbodiimide-resistant mutant is specifically defective in its ability to react with lipophilic carbodiimides. In addition, these and other findings indicate that the increase in proton permeability observed on extraction of isolated membrane vesicles with chaotropic agents is due exclusively to an effect on the carbodiimide-reactive component of the Ca2+, Mg2+-stimulated ATPase complex.
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PMID:The role of the carbodiimide-reactive component of the adenosine-5'-triphosphatase complex in the proton permeability of Escherichia coli membrane vesicles. 13 63

Single glycerinated rabbit psoas muscle fibers were skinned by splitting them lengthwise. The fiber segments thus obtained were more easily accessible to solutes in the surrounding medium than the intact fibers. Using such segments, active tension could be fully abolished by adding N-ethylmaleimide under conditions which lead to inhibition of actin activation of the ATPase activity of myosin. Such muscles could, however, develop tension after irrigation with myosin or with the water-soluble active myosin fragments heavy meromyosin (HMM) or its subfragment 1 (HMM-S1). The induced tensions increased with increasing protein concentration in the irrigating solution. At any given protein concentration, the tension generated by myosin was larger than that produced by HMM which was, in turn, greater than that induced by HMM-S1 e.g. at 15 mg/ml protein the tensions produced by these three myosin moieties were 44.0, 14.0 and 2.8 g/cm2, respectively. The tension was found to be intimately associated with ATP splitting; thus, HMM and HMM-S1 which have been treated with reagents abolishing actin-activated ATPase failed to induce tension development. A contractile force may thus be generated through the interaction with actin of the water-soluble, enzymatically active, myosin subfragments involving the splitting of ATP.
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PMID:Tension development in skinned glycerinated rabbit psoas fiber segments irrigated with soluble myosin fragments. 13 70

Experiments were undertaken to substantiate the hypothesis that the mechanism of the direct effect of ouabain on the renal excretion of electrolytes is the result of inhibition of the transport enzyme, (Na, K)-ATPase. In dogs hydrated with saline, an injection of 3H-ouabain into the unilateral renal artery produced a continuing marked increase in excretion of water and sodium from the kidney, but not from the counter kidney. At maximal diuresis--90 min after ouabain injection, both kidneys were removed to assay microsomal ATPase activity and determine radioactivity distributed in subcellular structures. It was demonstrated that 3H-ouabain was deposited in the microsome fraction obtained from the injected kidney in concentrations ranging from 10(-7) to 10(-6) M/kg wet weight, and (Na, K)-ATPase activity of this fraction was inhibited as compared with that of the microsomal fraction obtained from control kidneys. Since (Na, K)-ATPase activity of renal microsomes was significantly inhibited in vitro by more than 10(-7) M of ouabain, ouabain concentration in microsomes obtained from the injected kidney was considered to be sufficient to inhibit ATPase activity. These findings indicate that ouabain diuresis under the present condition is closely related to direct inhibitory effect of ouabain on (Na, K)-ATPase activity of microsomes in tubular cells.
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PMID:Intrarenal distribution and ATPase inhibiting activity of ouabain in dogs. 13 62

A ouabain-insensitive ATPase activity associated with the water-soluble proteins of the human and bovine erythrocyte membrane is demonstrated by means of activity-staining in polyacrylamide gels. The ATPase activity from both sources had an absolute requirement for Mg2+, activity becoming easily detectable at 0.2 mM Mg2+. At low Mg2+ concentrations added Ca2+ appeared to decrease the intensity of the ATPase stain. The activity is unaffected by monovalent cations, does not hydrolyse p-nitrophenyl phosphate and is not inhibited by 2 : 4 dinitrophenol. The ATPase has an apparent molecular weight of approximately 100 000 as determined by electrophoresis in acrylamide gels containing dodecyl sulphate.
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PMID:A water-soluble Mg2+-ATPase from erythrocyte membranes. 13 17

The purpose of this investigation was to determine whether or not the nasal glands of the roadrunner and the Coturnix quail show cytological specializations for salt secretion. In addition, the Na-K ATPase content of the quail gland was determined before and after drinking of saline solutions, in an effort to evaluate the functional status of the gland. The ability to maintain weight while drinking salt water was also measured as a general index of tolerance to saline conditions. The ultrastructure of the nasal glands of the roadrunner injected with salt and of quail drinking 200 mM NaCl was similar to that of salt glands in reptiles and the fresh-water acclimated duck. Numerous lateral cell evaginations and abundant mitochondria were present in the principal cell types. There was a significant increase in quail nasal gland Na-K ATPase when young birds were offered only saline solutions to drink. The ability of Coturnix quail to maintain weight while drinking saline solutions improves with age and at adulthood is comparable to that of some North American desert quail. Roadrunners were previously known to possess functional salt glands whereas quail were not. However the characteristic fine structure and the high Na-KATPase content of the quail nasal gland suggest that it is a salt gland.
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PMID:Evidence for the presence of nasal salt glands in the roadrunner and the Coturnix quail. 13 19


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