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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 distribution of ATPase activity in the flight muscle of Locusta migratoria L. was studied at the fine structural level after a brief fixation in formaldehyde or in glutaraldehyde. In both the cases, the final product of reaction -- fine grained electron dense precipitation--was clearly revealed in intact contractile muscle structures. The glutaraldehyde fixation provides a good preservation of all the ultrastructural components of muscle cell, and reveals deposites of the final product in sarcomeres at the resting length. However, after the glutaraldehyde fixation it is very difficult to recognize regions of fibrillar reaction on electronmicroscopic preparation. The formaldehyde fixation does not provide a good preservation of membranous structures. However after the formaldehyde fixation reacting regions are more extensive than after glutaraldehyde fixation, and, moreover, it is possible to demonstrate a correlation between the activity and the contraction of sarcomere.
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PMID:[Electron microscopic detection of ATPase activity in insect muscle after fixation with different fixatives]. 644 79

Pekin and Muscovy breeds of domestic ducks were reared from hatching to 10 weeks. Males and females of each breed were killed at weekly intervals and sartorius muscles were removed after the onset of rigor mortis. Fiber diameters were measured from macerated preparations after fixation with formaldehyde. All volumetric data were corrected to a common sarcomere length. Longitudinal and radial growth of muscles reached their maximum velocity during the fourth and fifth weeks, respectively. In Muscovies, heavier muscles in males relative to females were due to increased muscle length and cross sectional area. Faster early growth of Pekins relative to Muscovies was due to muscle length and fiber diameter. Histochemical analysis of supracoracoideus muscles frozen immediately postmortem showed that both adenosine triphosphatase and succinate dehydrogenase activity were negatively correlated with muscle fiber cross sectional area.
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PMID:Volumetric growth of muscle fibers in ducks. 645 44

Immunodominant regions of yeast plasma membrane H(+)-ATPase have been mapped by two different approaches. A rabbit polyclonal antibody was used to screen a library of random fragments of the ATPase gene in a bacterial expression plasmid. In addition, the epitopes recognized by a panel of mouse monoclonal antibodies against the ATPase were mapped by reactions with defined fragments of the enzyme expressed in Escherichia coli. Both methodologies indicated that two regions within the amino-terminal part of the ATPase (at amino acid positions 5-105 and 168-255) contain most of the antigenic determinants. The accessibility of the monoclonal antibodies to their epitopes in native and solvent-perturbed ATPase preparations was investigated by immunofluorescence studies on yeast protoplasts. Cells fixed and permeabilized with formaldehyde were either treated with or without detergents and organic solvents. ELISA competition tests with plasma membrane vesicles and with detergent-purified ATPase incubated in solution with the monoclonal antibodies gave similar results. All the epitopes were accessible in detergent-treated ATPase preparations. In contrast, only the epitopes at amino acids 24-56 were accessible in ATPase preparations not treated with detergents or organic solvents. These epitopes were cytoplasmic because protoplast permeabilization was required for decoration by the reactive monoclonal antibodies.
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PMID:Epitope mapping and accessibility of immunodominant regions of yeast plasma membrane H(+)-ATPase. 768 77

The pregnant rats were treated with formaldehyde (0.5 mg/kg daily per os) during whole period of pregnancy. The activity of cytochrome-c-oxidase, malate dehydrogenase, nucleotidase, glucose-6-phosphatase, beta-glucuronidase, N-acetyl-beta-glucosaminidase, beta-galactosidase, H(+)-ATPase, glutamate dehydrogenase, NAD- and NADP-isocitrate dehydrogenase, fructose-bisphosphate aldolase, glucose-6-phosphate dehydrogenase and content of protein in liver celts of offsprings (newborns, 2 weeks age and 2 months age) were studied. It was shown differences in development enzyme systems of control and experimental animals during ontogenesis.
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PMID:[Experimental study of the effect of formaldehyde during embryogenesis on the activity of rat liver enzyme systems in ontogenesis]. 913 53

We have examined lipid peroxidation (LPO) and fatty acid acyl chain dynamics in synaptosomal membranes isolated from aged rat (Fischer 344 x Brown Norway F1 hybrids) brains, correlating these results with measurements of enzymatic activity of the synaptic plasma membrane Ca2(+)-ATPase (PMCA). Calcium-dependent ATPase activity in these membranes exhibits progressive decreases with a maximal loss of activity with age of approximately 35%. The sensitivity of this membrane-bound ion transporter to the lipid composition of the surrounding membrane, as well as the high abundance of oxidatively sensitive polyunsaturated fatty acyl chains in synaptosomal membranes, suggests that this age-related loss in catalytic turnover may result from LPO-mediated protein modification and/or changes in the physical structure of the bilayer. However, high-performance liquid chromatography analysis of 2,4-dinitrophenylhydrazone derivatives reveals no significant age-related increases in the content of reactive aldehydes (malondialdehyde, formaldehyde, acetaldehyde or acetone) which comprise breakdown products of lipid peroxidation. Electron paramagnetic resonance measurements employing 5- and 12-stearic acid spin labels with the nitroxide reporter groups at two depths in the bilayer were used to assess the fatty acyl chain dynamics (fluidity) of synaptosomal membranes. The resulting spectra demonstrate anisotropic lipid dynamics of two populations of lipids, i.e. lipids in direct association with membrane proteins (boundary lipids) and bulk lipids that do not directly associate with proteins. The nanosecond dynamics of both lipid populations is unaltered with age indicating that any compositional changes occurring with age are insufficient to result in alterations in bilayer fluidity relevant to PMCA activity. Thus, the observed age-related decline in PMCA activity may be explained by direct modification of membrane protein.
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PMID:Decrease in Ca-ATPase activity in aged synaptosomal membranes is not associated with changes in fatty acyl chain dynamics. 986 36

Cytochemical data in the literature reporting localization of sodium, potassium adenosine triphosphatase (Na(+), K(+)-ATPase) in the blood-brain barrier (BBB) have been contradictory. Whereas some studies showed the enzyme to be located exclusively on the abluminal endothelial plasma membrane, others demonstrated it on both the luminal and abluminal membranes. The influence of fixation on localization of the enzyme was not considered a critical factor, but our preliminary studies showed data to the contrary. We therefore quantitatively investigated the effect of commonly used fixatives on the localization pattern of the enzyme in adult rat cerebral microvessels. Fixation with 1%, 2%, and 4% formaldehyde allowed deposition of reaction product on both the luminal and abluminal plasma membranes. The luminal reaction was reduced with increasing concentration of formaldehyde. Glutaraldehyde at 0.1%, 0.25%, 0.5%, in combination with 2% formaldehyde, drastically inhibited the luminal reaction. The abluminal reaction was not significantly altered in all groups. These results show that luminal localization of BBB Na(+), K(+)-ATPase is strongly dependent on fixation. The lack of luminal localization, as reported in the literature, may have been the result of fixation. The currently accepted abluminal polarity of the enzyme should be viewed with caution.
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PMID:Luminal localization of blood-brain barrier sodium, potassium adenosine triphosphatase is dependent on fixation. 1082 Jan 59

Numerous cytochemical studies have reported that calcium-activated adenosine triphosphatase (Ca2+-ATPase) is localized on the abluminal plasma membrane of mature brain endothelial cells. Since the effects of fixation and co-localization of ecto-ATPase have never been properly addressed, we investigated the influence of these parameters on Ca2+-ATPase localization in rat cerebral microvessel endothelium. Formaldehyde at 2% resulted in only abluminal staining while both luminal and abluminal surfaces were equally stained following 4% formaldehyde. Fixation with 2% formaldehyde plus 0.25% glutaraldehyde revealed more abluminal staining than luminal while 2% formaldehyde plus 0.5% glutaraldehyde produced vessels with staining similar to 4% and 2% formaldehyde plus 0.25% glutaraldehyde. The abluminal reaction appeared unaltered when ATP was replaced by GTP, CTP, UTP, ADP or when Ca2+ was replaced by Mg2+ or Mn2+ or p-chloromercuribenzoate included as inhibitor. But the luminal reaction was diminished. Contrary to previous reports, our results showed that Ca2+-specific ATPase is located more on the luminal surface while the abluminal reaction is primarily due to ecto-ATPase. The strong Ca2+-specific-ATPase luminal localization explains the stable Ca2+ gradient between blood and brain, and is not necessarily indicative of immature or pathological vessels as interpreted in the past.
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PMID:Calcium-dependent ATPase unlike ecto-ATPase is located primarily on the luminal surface of brain endothelial cells. 1093 19

In Methanobacterium thermoautotrophicum, the protonmotive force for the H+-translocating ATPase consists mainly of a transmembrane electrical gradient (Deltapsi). These cells do not establish a significant transmembrane pH gradient (inside alkaline) and, in fact, if the suspending medium is of pH >/= 7.0, the pH gradient may be reversed-i.e., inside acid with respect to the extracellular pH. These studies show by both 23Na NMR and 22Na+ distribution that Na+ extrusion with the generation of Deltapsi precedes methanogenesis in Mb. thermoautotrophicum. It is calculated that the newly established Na+ gradients increase Deltapsi by approximately 50 mV (inside negative). There is no detectable H+ extrusion during methane synthesis; instead there is a high rate of H+ consumption for methane synthesis and an increase in internal pH. This was supported by 31P NMR experiments, which showed an internal pH shift from 6.8 to 7.6. With the cells maintained at an external pH of 7.2, the initial transmembrane pH gradient of -0.4 (inside acid) at 60 degrees C is equivalent to Deltapsi of + 27 mV (inside positive); after 20 min of incubation, the transmembrane pH gradient is + 0.4 (inside alkaline), which at 60 degrees C is equivalent to Deltapsi of -27 mV (inside negative). Actively respiring cells generated a protonmotive force of -198 mV. It is proposed that energy for CO2 reduction to the level of formaldehyde (the first step in methane synthesis) in Mb. thermoautotrophicum is derived from the Deltapsi generated by electrogenic Na+ extrusion. The protonmotive force required for ATP synthesis consists primarily of Deltapsi and appears to be the result of both an electrogenic Na+ extrusion and a pH gradient (inside alkaline) which develops during methanogenesis.
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PMID:Ion transport and methane production in Methanobacterium thermoautotrophicum. 1160 73

Thymus glands of chicks with leukemia induced by BAI strain A (myeloblastosis) virus were fixed in cold 4 per cent formaldehyde-sucrose. Frozen sections were incubated in the ATPase medium of Wachstein and Meisel and studied by light microscopy and electron microscopy. The ATPase activity of the virus is localized to the outermost membrane of the virus. The membrane of the blast-like cells of the thymus cortex from which the virus emerges, by budding, also possesses such activity. It appears likely that the outermost membrane of the virus is derived from the plasma membrane of these cells.
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PMID:Electron microscopic study of the ATPase activity of the BAI strain A (myeloblastosis) avian tumor virus. 1393 25

Cytochemical techniques employing lead-precipitation of enzymically released inorganic phosphate have been widely used in attempts to localize the plasma membrane proton pump (H(+)-ATPase) in electron micrographs. Using Avena sativa root tissue we have performed a side-by-side comparison of ATPase activity observed in electron micrographs with that observed in in vitro assays using ATPases found in the soluble and plasma membrane fractions of homogenates. Cytochemical analysis of oat roots, which had been fixed in glutaraldehyde in order to preserve subcellular structures, identifies an ATPase located at or near the plasma membrane. However, the substrate specificity and inhibitor sensitivity of the in situ localized ATPase appear identical to those of an in vitro ATPase activity found in the soluble fraction, and are completely unlike those of the plasma membrane proton pump. Further studies demonstrated that the plasma membrane H(+)-ATPase is particularly sensitive to inactivation by the fixatives glutaraldehyde and formaldehyde and by lead. In contrast, the predominant soluble ATPase activity in oat root homogenates is less sensitive to fixation and is completely insensitive to lead. Based on these results, we propose a set of criteria for evaluating whether a cytochemically localized ATPase activity is, in fact, due to the plasma membrane proton pump.
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PMID:Cytochemical localization of ATPase activity in oat roots localizes a plasma membrane-associated soluble phosphatase, not the proton pump. 1666 98


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