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)

We attempted separations by affinity chromatography of the Na+/K+-dependent adenosinetriphosphatase, using Sepharose 6B covalently coupled with ouabain, either on microsomal fractions or on preparations purified by discontinuous sucrose density gradient ultracentrifugation. The material, specifically eluted with ouabain, was tested to evaluate the recovery of ATPase activity and ouabain binding capacity. The results have shown the efficiency of this technique for (Na+/K+)-APTase isolation.
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PMID:Na+/K+-dependent adenosinetriphosphatase in rabbit kidney. Separation by affinity chromatography. 23 68

The inotropic effect of 1.25 times 10(-6)M acetylstrophanthidin (ACS) and the influx and efflux of labeled potassium (42K+) were studied in the arterially perfused rabbit interventricular septum under control conditions and during respiratory acidosis. An increase in the CO2 content of the gas mixture with which the modified Ringer's solution was equilibrated from 5 to 30% reduced the perfusate pH from 7.37 to 6.66. The increment in developed tension in the presence of ACS was 3.0 +/- 0.2 g (n equals 10) under control conditions, but it was greater, 7.1 +/- 0.9 g (N equals 9) during acidosis (P less than less than 0.001). The net K+ loss due to an increase in K+ efflux was 1.8 +/- 0.2 mmoles/kg wet weight in control experiments but only 0.1 +/- 0.1 mmoles/kg net weight under acidotic conitions (P less than less than 0.001); in seven of nine experiments in respiratory acidosis, no increase in K+ efflux occurred despite a marked positive inotropy. In three septums, K+ influx was reduced by ACS during respiratory acidosis. These results demonstrate that during acidosis ACS inhibits sodium-potassium adenosinetriphosphatase (Na+-K+ ATPase) and causes an inotropic effect but does not increase K+ efflux. K+ efflux cannot be linked to calcium (Ca2+) influx or regarded as the controlling factor of glycoside-induced inotropy. The results give further support to the proposal that digitalis-induced inotropy is secondary to an enhancement of a Na+-Ca2+ exchange system.
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PMID:Glycoside inotropy in the absence of an increase in potassium efflux in the rabbit heart. 23 98

The interaction of myosin subfragment-1 (S-1) with 4,4'-bis(1-anilinonaphthalene 8-sulfonate) (bis-ANS) has been studied by monitoring the fluorescence of the latter when the two components form a complex. Because ATP and ATP analogs partially displace complexed bis-ANS it has also been possible to study interactions of S-1 and nucleotides by using the displacement effect. Approximate values of the parameters of these various interactions have been measured. Some possible applications of bis-ANS have been explored. For example, it provides a very convenient method for obtaining the Michaelis constant, Km, in steady-state S-1 nucleoside triphosphatase; this particular application has also provided some evidence for inferring that in Ca2+ (but not in Mg2+) adenosinetriphosphatase (ATP phosphohydrolase, EC 3.6.1.3) S-1 behaves like a mixture of two components, each with its own Km. Clear energy transfer occurs between tryptophan residues and bound bis-ANS. The fluorescence also suggests that S-1 undergoes some slow relaxations following substrate binding.
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PMID:4,4'-Bis (1-anilinonaphthalene 8-sulfonate) (bis-ANS): a new probe of the active site of myosin. 26 28

Rabbit alpha-tropomyosin was cleaved into two pieces at the cysteine residue of each chain. The products were separated by chromatography and characterized by amino acid analysis, molecular weight determination in benign and denaturing solvents, optical rotation and circular dichroism. When the cleavage reaction was carried out under mild conditions which preserve the two-chain structure there was considerable loss of alpha-helix in each segment. Thermal stability studies, monitored by optical rotation and circular dichroism, showed that the transition temperature of the N-terminal fragment at pH 7.6 was approximately 17 degrees C higher than that of the C-terminal fragment. In acid solutions there is little difference in the thermal stability of the two segments. The least stable part of the molecule is concluded to be between residues 133 and 205 and this includes the troponin-binding site. The relative stabilities found for segments of rabbit alpha-tropomyosin differ from recent published conclusions and this may be a result of the different methods used to study the loss of the alpha-helical conformaton. The two tropomyosin fragments, unlike the parent tropomyosin, do not inhibit actomyosin adenosinetriphosphatase when mixed with troponin. The fragments did not show any of the aggregation properties of tropomyosin and did not combine with actin. The N-terminal fragment did not complex with troponin but there was some evidence for an interaction between the C-terminal fragment and troponin.
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PMID:Stability of segments of rabbit alpha-tropomyosin. 61 6

Defective potassium excretion with clinical acidosis, associated with fixed moderate sodium wasting, has been found to be a common abnormality in lead nephropathy. Lead poisoning has been shown by others to be associated with depression of the renin-aldosterone system and of sodium and potassium activated adenosinetriphosphatase (ATPase). Since these hormonal defects may contribute to the hyperkalemia and are reversible, lead poisoning should be treated aggressively. Management also requires proper regulation of dietary sodium, correction of acidosis, limitation of dietary potassium, and minimal use of antihypertensive agents, as well as the administration of allopurinal for urate control.
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PMID:Hyperkalemia and acidosis in lead nephropathy. 94 Oct 56

Changes in motor innervation were compared with histologic and histochemical pattern of muscle fibers in three biopsies of central core disease, four biopsies of nemaline myopathy, one biopsy of myotubular myopathy, and three biopsies of mitochondrial myopathy. Evidence of collateral reinnervation was obtained only in one biopsy from central core disease. In other biopsies, no structural or ultrastructural abnormality of axis cylinders, myelin, or myoneural junction suggesting denervation were observed. The only relevant change found in centronuclear myopathy and to a lesser extent in nemaline myopathy was an unusual smallness and simplication of motor endings, suggesting delayed or impaired maturation. Muscle fibers strongly reactive for both adenosinetriphosphatase and nicotinamide-adenine dinucleotide diaphorase, observed in central core disease and mitochondrial myopathy, were not associated with increased terminal innervation ratio.
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PMID:Changes in motor innervation and histochemical pattern of muscle fibers in some congenital myopathies. 98 11

A method for measuring inwardly directed transmembrane tracer flow during the cardiac cycle was developed and applied to a study of 42K influx in frog atrial trabeculae. A fine frog atrial fiber was suspended in a stream of nonisotopic perfusate into which a smaller tracer-containing bolus could be injected, subjecting the fiber to a brief, controlled exposure to the tracer at any desired point in the cardiac cycle. In an experiment, the tissue was exposed to a fixed number of radioactive pulses at a selected point in the cardiac cycle; a brief flush with nonradioactive perfusate removed ambient and extracellular label and an extended wash and removed the remaining intracellular tracer for radioassay. The same procedure was repeated at different points in the cycle, and the resulting tracer uptake at each point measured the relative influx of the particular ion. In this way, a characteristic and reproducible 42K influx profile was demonstrated which exhibited a marked drop below diastolic values during the first 500 msec or so of the action potential followed by a rise and an overshoot above resting values. The time of return to the resting level was somewhat uncertain but was tentatively placed in the vicinity of rapid repolarization. We suggest that the rise and the overshoot reflect the activity of the membrane Na+, K+-adenosinetriphosphatase.
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PMID:Potassium influx in the frog atrium during the cardiac cycle. 108 36

Evidence that the sodium plus potassium activated adenosinetriphosphatase ((Na + K)-ATPase) is present and functions normally in a red blood cell ghost is summarised. The case is then argued that since ghost move neither sodium nor potassium against an electrochemical gradient, the (Na+ + K)-ATPase is not in itself sufficient to generate transmembrane gradients of sodium and potassium ions. If it is not sufficient in ghost, then it cannot be sufficient in intact cells, but most somehow work co-operatively with the cytoplasm. An alternative hypothesis to that of carrier-mediated transported is then proposed, and shown to be consistent with data on intact cells, membrane homogenates, ghosts, and membrane vesicles derived from bacteria.
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PMID:The sodium pump: a ghost story. 122 69

The concentration of drug necessary to inhibit lymphocyte transformation by 50 per cent (I50 value) was determined for the glucocorticoid prednisolone-21-phosphate, and for the sodium-potassium adenosinetriphosphatase inhibitor ouabain, in 37 persons representing the full range of ocular and cellular glucocorticoid sensitivity. The lymphocytes of patients with primary open-angle glaucoma, and of high ocular responders to glucocorticoids, were more sensitive to prednisolone-21-phosphate than were those of ocular low and intermediate responders. By contrast, there was no significant difference in sensitivity to ouabain. There was also no significant correlation of lymphocyte sensitivity to prednisolone-21-phosphate with that to ouabain. These results provide indirect evidence that the increased cellular sensitivity to glucocorticoids in primary open-angle glaucoma is a specific effect, and not merely representative of a general vulnerability of "sick cells."
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PMID:Differential sensitivity at the cellular level in primary open-angle glaucoma: prednisolone and ouabain. 126 71

With the use of myosin adenosinetriphosphatase (ATPase) and immunofluorescence staining methods, the adaptive responses of intrafusal and extrafusal fibers to endurance swimming were studied in frozen sections of rat soleus (SOL) and extensor digitorum longus (EDL) muscles. Glycogen depletion confirmed muscle fatigue at the end of a standardized bout of exercise. No significant age-dependent changes in myosin isoforms were detected in any fibers. The 12-wk training increased type I fibers by 10.9% in the SOL and type IIa fibers in the EDL by 16.6%. In trained muscle sections, both staining methods identified a permuted chain fiber, expressed the same as the myosin isoform in the bag2 fiber. However, no exercise-induced change of myosin isoform profile was found in the bag1 and bag2 fibers. Myosin ATPase (and immunofluorescence) staining showed the percentage of permuted chain fibers increased from 0 to 6.7% (5.6%) after 6 wk of training and to 19.2% (14.1%) after 12 wk of training and that it was still at 6.1% (4.2%) 10 wks after training. A novel myosin isoform may thus be expressed in nuclear chain fibers by repetitive recruitment of muscle spindles.
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PMID:Novel myosin isoform in nuclear chain fibers of rat muscle spindles produced in response to endurance swimming. 128 26


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