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)

1. Na(+)-K+ and Mg(2+)-tissue ATPases of the freshwater crab Oziotelphusa senex senex showed increasing inhibition when exposed to a sublethal concentration (1.86 mg/l = 0.1 of LC50) of endosulfan for 1-30 days. 2. Na(+)-K(+)-ATPase activity in all tissues (thoracic nerve mass, gill, hepatopancreas and claw muscle) was higher than Mg(2+)-ATPase activity. 3. After 30 days exposure tissue Mg(2+)-ATPase was less affected than Na(+)-K(+)-ATPase. 4. Crabs exposed to endosulfan and then returned to uncontaminated water showed greater recovery of Mg(2+)-ATPase than Na(+)-K(+)-ATPase with 90-95% recovery after 1 day exposure and 60-65% recovery after 30 days exposure. 5. Changes in behaviour of the crabs were noted after 7 days exposure to endosulfan with progressive loss of coordination, decreased activity and increased exudation of mucus.
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PMID:Tissue ATPase activity and recovery in the freshwater crab Oziotelphusa senex senex exposed to a sublethal concentration of endosulfan for varying periods of time. 168 16

In the present study, antibodies were raised against the Mg(2+)-ATPase and the immunological relationships between the enzyme and other ATPase from a variety of biological membranes were determined. The anti Mg(2+)-ATPase antiserum inhibited 85% of the enzyme activity from A. laidlawii membranes. We demonstrate a specific selectivity of Mg(2+)-ATPase antiserum for antigenic determinants of the A. laidlawii membranes. Immunoblot studies of A. laidlawii membrane peptides indicated labeling of five bands, 66KD, 49KD, 34KD, 26KD and 13KD, corresponding to five subunits of the ATPase in A. laidlawii membranes.
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PMID:Immunological properties of antibodies against Mg(2+)-ATPase from Acholeplasma laidlawii membranes. 171 30

The regulatory light chains (RLCs) located on the myosin head, regulate the interaction of myosin with actin in response to either Ca2+ or phosphorylation signals. The RLCs belong to a family of calcium binding proteins and are composed of four "EF hand" ancestral calcium binding motifs (numbered I to IV). To determine the role of the first EF hand (EF hand I) in the regulatory process, chimaeric light chains were constructed by protein engineering, by switching this region between smooth muscle and skeletal muscle myosin RLCs. For example, chimaera G(I)S consisted of EF hand I of the smooth muscle (gizzard) RLC and EF hands II to IV of the skeletal muscle RLC, whereas chimaera S(I)G consisted of EF hand I of the skeletal muscle RLC and EF hands II to IV of the smooth muscle RLC. The chimaeric RLCs were expressed in Escherichia coli using the pLcII expression system, and after isolation and purification their regulatory properties were compared with those of wild-type smooth and skeletal muscle myosin RLCs. The chimaeric RLCs bound to the myosin heads in scallop striated muscle myofibrils from which the endogenous RLCs had been removed ("desensitized" myofibrils) with similar affinities to those of the wild-type smooth and skeletal muscle RLCs. Both chimaeric RLCs were able to regulate the actin-activated Mg(2+)-ATPase activity of scallop myosin: G(I)S inhibited the ATPase in the presence and absence of Ca2+, like the wild-type skeletal muscle RLC, while S(I)G inhibited the myosin ATPase in the absence of Ca2+, and this inhibition was relieved on Ca2+ addition, in the same way as the wild-type smooth muscle RLC. Thus the type of regulation that the RLCs confer on the myosin is determined by the source of EF hands II to IV rather than that of EF hand I.
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PMID:Chimaeric myosin regulatory light chains: sub-domain switching experiments to analyse the function of the N-terminal EF hand. 182 64

A chemical modification of G-actin with (m-maleimidobenzoyl)-N-hydroxysuccinimide ester (MBS) impairs actin polymerization [Bettache, N., Bertrand, R., & Kassab, R. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 6028-6032]. MBS-actin recovers the ability to polymerize when a 2-fold molar excess of phalloidin is added in 30 mM KCl/2 mM MgCl2/20 mM Tris-HCl (pH 7.6). The resulting polymer (MBS-P-actin) is highly potentiated so that it activates the Mg(2+)-ATPase of S1 more strongly than native F-actin. The affinity of MBS-P-actin for S1 in the presence of ATP (KATPase) is about four times higher than that of native F-actin, although the maximum velocity at infinite actin concentration (Vmax) is almost the same. This high activation is not due to a cross-linking between MBS-P-actin and the S1 heavy chain, since no substantial amount of cross-linking was observed in SDS gel electrophoresis. Direct binding studies and ATPase measurements showed that the modification of actin with MBS impairs the binding of tropomyosin. Tropomyosin binding can be improved considerably by the addition of troponin. However, the regulation mechanism of the acto-S1 ATPase activity by troponin-tropomyosin is damaged. The addition of troponin-tropomyosin reduces the S1 ATPase activation by MBS-P-actin to the same level as that of native F-actin in 30 mM KCl/2.5 mM ATP/2 mM MgCl2, but there is no difference in the ATPase activation in the presence and absence of Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interaction of maleimidobenzoyl actin with myosin subfragment 1 and tropomyosin-troponin. 182 94

A number of chemicals are known to potentiate the hepatotoxicity of carbon tetrachloride. The halocarbon trichloroethylene was shown in a previous study to enhance both carbon tetrachloride-induced toxicity and lipid peroxidation in isolated hepatocytes. In this study three other chlorocarbons have been investigated in order to determine whether this interaction was peculiar to trichloroethylene or common to chlorinated solvents. Hepatocyte suspensions were exposed to carbon tetrachloride at subthreshold levels of toxicity and various concentrations of 1,1,1-trichloroethane, tetrachloroethylene, and chloroform over an eightfold concentration range. Plasma membrane preparations were exposed to tetrachloroethylene and carbon tetrachloride and effects on Mg(2+)- and Na(+)-K(+)-ATPase activities determined. None of the treatments alone caused statistically significant toxicity. Combined treatments resulted in toxicity as demonstrated by potassium ion, alanine aminotransferase, and lactate dehydrogenase leakage from the cells on coincubation of carbon tetrachloride with each of the other halocarbons studied. Only tetrachloroethylene and chloroform were found to potentiate lipid peroxidation, however. In liver plasma membranes no changes in Na(+)-K(+)-ATPase were observed with any of the treatments and only the highest dose of tetrachloroethylene was able to inhibit Mg(2+)-ATPase activity. There was no increase in this inhibition on coincubation with carbon tetrachloride, which does not support involvement of ATPases in combined halocarbon toxicity. In conclusion, the data suggest a mechanism of action common to this class of chemical although its specific nature remains to be established.
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PMID:Potentiating effects of chlorinated hydrocarbons on carbon tetrachloride toxicity in isolated rat hepatocytes and plasma membranes. 182 22

Nifedipine, a 1,4-dihydropyridine antihypertensive drug, inhibited the basal activity of erythrocyte Ca2+,Mg(2+)-ATPase of hypertensive individuals in a concentration-dependent manner. About 50% inhibition was obtained at nifedipine concentrations greater than or equal to 300 microM. The extent of inhibition of the ATPase action was increased in the presence of calmodulin. Maximal inhibition at 400 microM was 76%. Furthermore, the activity of the partially trypsinized enzyme was inhibited by about 50% by 300 microM nifedipine. Similar results were obtained with membranes from normotensive individuals. These findings suggest that nifedipine could prevent Ca(2+)-pumping by the erythrocyte Ca2+,Mg(2+)-ATPase.
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PMID:Inhibition of erythrocyte membrane Ca(2+)-pumping ATPase of hypertensive humans by nifedipine, a calcium entry blocker. 182 16

This paper deals with the toxicity of mercuric chloride to different ATPases in the intestine of mudskipper (Boleophthalmus dentatus). Mudskippers were exposed to four sublethal concentrations of mercuric chloride for three durations. The specific activities of Na+, K(+)-ATPase, Ca(2+)-ATPase, Mg(2+)-ATPase, Ca2+, HCO3(-)-ATPase, and Mg2+, HCO3(-)-ATPase were estimated. There was linear inhibition of all the enzymes with increasing mercuric chloride concentration as well as exposure duration. The Na+,K(+)-ATPase was found to be the enzyme most affected, followed by other ion-dependent ATPases. Inhibition of all the enzymes indicates severe damage to the intestinal cells, resulting in a blockage of the transport of substances across the membrane.
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PMID:Mercuric chloride-induced inhibition of different ATPases in the intestine of mudskipper, Boleophthalmus dentatus. 182 8

Intracellular free Mg2+ concentration [( Mg2+]i) has been shown to increase markedly during ischemia from 0.6 to 3.2 mM and remain elevated severalfold at 1.5 mM after reperfusion of the stunned heart. The significance of this rise in [Mg2+]i after reperfusion on cellular function is not well known. To determine whether this increase in free [Mg2+] would alter the function of the sarcoplasmic reticulum (SR), the effects of an increase in free [Mg2+] on the SR Ca(2+)-dependent Mg(2+)-adenosinetriphosphatase (ATPase) activity were examined in SR isolated from Langendorff-perfused, isovolumic rabbit hearts after 15 min of reversible ischemia (global stunning). Oxalate-supported Ca2+ transport, assessed under identical conditions (0.4 mM free Mg2+, 15 microM free Ca2+), was reduced from 495 +/- 29 to 395 +/- 27 nmol Ca2+.mg protein-1.min-1 in control and stunned hearts, respectively, indicating a defect in enzyme function. This defect was confirmed by a decrease in the maximal Ca(2+)-dependent Mg(2+)-ATPase activity. An increase in the free [Mg2+] to simulate conditions after reperfusion leads to a decrease in the Ca2+ sensitivity of the SR Mg(2+)-ATPase. Fifty percent activation was shifted from a control free [Ca2+] of 0.42 microM at 0.6 mM free [Mg2+] to 0.63 microM free [Ca2+] at 1.2 mM free [Mg2+], conditions that simulate the reperfused stunned myocardium. These results indicate that after stunning the observed decline in SR Ca2+ transport, determined under similar incubation conditions, may be further jeopardized by the sustained increase in free [Mg2+].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of increased free [Mg2+]i with myocardial stunning on sarcoplasmic reticulum Ca(2+)-ATPase activity. 183 Apr 58

3-(2,6-Diisopropyl-4-phenoxyphenyl)-1-tert-butylcarbodiimide (DFCD), a toxic metabolite and photodegradation product of the propesticide diafenthiuron, and dicyclohexylcarbodiimide (DCCD), a commonly used biochemical inhibitory probe, inhibited Mg(2+)-, Na+K(+)-, and Ca2+Mg(2+)-ATPase activities in preparations from bulb mites (Rhizoglyphus echinopus (Fumouze and Robin)), twospotted spider mites (Tetranychus urticae Koch), and bluegill (Lepomis macrochirus Rafinesque) brain. DCCD was more active than DFCD, but neither carbodiimide was very potent. A possible exception occurred with DCCD, which caused 100% inhibition of bulb mite oligomycin-sensitive Mg(2+)-ATPase activity at a concentration of 0.1 mM. Using house fly, Musca domestica L., thorax mitochondrial Mg(2+)-ATPase, we showed that the binding domain for both carbodiimides was in the F0 portion of the enzyme, probably the transmembrane proton channel which is the known site of DCCD binding in proton-translocating ATPases. Certain other specific acaricides were inhibitors (greater than 50% at 0.1 mM) of ATPase preparations from bulb mites. These acaricides included chloropropylate, bromopropylate, oxythioquinox, cyhexatin, and flubenzimine (Mg2+ and Na+K(+)-ATPase), and ovex, chlorbenside, and propargite (Mg(2+)-ATPase). The role of ATPase inhibition in the modes of acaricidal and insecticidal actions of diafenthiuron, the two carbodiimides, and the other compounds is discussed.
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PMID:Inhibition of ATP dephosphorylation by acaricides with emphasis on the anti-ATPase activity of the carbodiimide metabolite of diafenthiuron. 183 78

Following cell fractionation in sucrose density gradients, plasma membrane Mg(2+)-ATPase from Pachysolen tannophilus was studied. The ATPase displayed an apparent Km for ATP of 1.42 mM and was inhibited by high concentrations of Mg2+. The inhibitory effects of ethanol, 1-propanol, 1-butanol, and benzyl alcohol on Mg(2+)-ATPase were evaluated, and the concentration of each alcohol that inhibited ATPase activity by 50% (IC50) was determined. The IC50 decreased as the chain length of the alcohol increased. Moreover, the IC50 for ATPase activity was similar to the IC50 for growth rate, suggesting an association between impaired growth and ATPase inhibition. Almost complete inhibition of ATPase activity occurred at temperatures approaching 60 degrees C, and the optimal temperature was around 44 degrees C for ATPase from both control and ethanol-treated cells. Inclusion of 50 mM MgCl2 or CaCl2 in the medium did not rescue cells from the deleterious effects of ethanol.
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PMID:Plasma membrane Mg(2+)-ATPase of Pachysolen tannophilus: characterization and role in alcohol tolerance. 183 33


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