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:3.6.3.1 (Mg2+-ATPase)
1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effects of commonly used purification procedures on the yield and specific activity of (Na+ + K+)-ATPase (Mg2+-dependent, Na+ + K+-activated ATP phosphohydrolase, EC 3.6.1.3), the turnover number of the enzyme, and the kinetic parameters for the ATP-dependent ouabain-enzyme interaction were compared in canine brain, heart and kidney. Kinetic parameters were estimated using a graphical analysis of non-steady state kinetics. The protein recovery and the degree of increase in specific activity of (Na+ + K+)-ATPase and the ratio between (Na+ + K+)-ATPase and Mg2+-ATPase activities during the successive treatments with deoxycholate, sodium iodide and glycerol were dependent on the source of the enzyme. A method which yields highly active (Na+ + K+)-ATPase preparations from the cardiac tissue was not suitable for obtaining highly active enzyme preparations from other tissues. Apparent turnover numbers of the brain (Na+ + K+)-ATPase preparations were not significantly affected by the sodium iodide treatment, but markedly decreased by deoxycholate or glycerol treatments. Similar glycerol treatment, however, failed to affect the apparent turnover number of cardiac enzymes preparations. Cerebral and cardiac enzyme preparations obtained by deoxycholate, sodium iodide and glycerol treatments had lower affinity for ouabain than renal enzyme preparations, primarily due to higher dissociation rate constants for the ouabain.enzyme complex. This tissue-dependent difference in ouabain sensitivity seems to be an artifact of the purification procedure, since less purified cerebral or cardiac preparations had lower dissociation rate constants. Changes in apparent association rate constants were minimal during the purfication procedure. These results indicate that the presentyl used purification procedures may alter the properties of membrane (Na+ + K+)-ATPase and affect the interaction between cardiac glycosides and the enzyme. The effect of a given treatment depends on the source of the enzyme. For the in vitro studies involving purified (Na+ + K+)-ATPase preparations, the influence of the methods used to obtain the enzyme preparation should be carefully evaluated.
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PMID:Membrane (Na+ + K+)-ATPase of canine brain, heart and kidney. Tissue-dependent differences in kinetic properties and the influence of purification procedures. 14 5

(Na+ + K+)-ATPase activity is demonstrated in plasma membranes from pig mesenteric lymph nodes. After dodecyl sulfate treatment plasma membranes have an 18-fold higher (Na+ + K+)-ATPase activity, while their ouabain-insensitive Mg2+-ATPase is markedly lowered. A solubilized (Na+ +K+)-ATPase fraction, obtained by Lubrol WX treatment of the membranes, has very high specific activity (21 mumol Pi/h per mg protein). Concanavalin A has no effect on these partially purified (Na+ + K+)-ATPase, while inhibits (40%) this activity in less purified fractions which still contain Mg2+-ATPase activity.
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PMID:Studies of (Na+ + K+)-sensitive ATPase activity in pig lymphocytes. Effects of concanavalin A. 14 92

The activities of Ca2+, Mg2+-ATPase and Na+, K+-ATPase and the permeability of reconstituted human erythrocytes for Na and K ions were measured, using Ca2+-EGTA, Ca2+ATP and Ca2+-sodium citrate buffers. It was found that the increase in the Ca2+/chelate ratio caused stimulation of Ca2+, Mg2+- and Na+, K+-Atpases and an increase in the rate constants of ouabain--dependent 42K+ influx and 22Na+ efflux from the erythrocytes. The use of the Ca2+-sodium citrate system as a calcium buffer did not change the parameters of the functional state of erythrocyte membranes. The data obtained are discussed in terms of a possible role of calcium ions, which are bound to the inner surface of the erythrocyte membrane, in the regulation of the systems of active and passive transport of cations.
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PMID:[The effect of membrane-bound calcium on the activity of adenosine triphosphatase from erythrocytes and erythrocyte permeability for monovalent cations]. 14

Calcium transport from red cells was measured in seventeen patients with congenital or hereditary spherocytosis (HS). The efflux remained at a lower level in resealed ghost cells of patients than in normal cells both in the presence and absence of adenosine triphosphate (ATP). We studied the activities of Ca2+,Mg2+-ATPase, ouabain-sensitive Na+,K+-ATPase, Mg2+-ATPase and Ca2+-(spectrin-)ATPase in cell membranes prepared by washing the cells with hypotonic medium. The mean +/-SD Ca2+,Mg2+-ATPase/Mg2+-ATPase of HS patients was 3.34 +/- 1.06, and 2.81 +/- 0.42 in control subjects. Na+,K+-ATPase/Mg2+-ATPase was 2.38 +/- 0.38 in HS cells compared to 2.01 +/- 0.41 in normal cells. Ca2+-ATPase/Mg2+-ATPase of HS membranes was 0.57 +/- 0.18 and the control value 0.43 +/- 0.08. These data indicate calcium retention in the erythrocytes of HS patients in spite of increases in Ca2+,Mg2+-ATPase activity in the majority of patients.
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PMID:Calcium transport and adenosine triphosphatase activities of erythrocyte membranes in congenital spherocytosis. 14 26

The article deals with the influence of sodium dodensylsulfate, lubrol and also of inhibition of Na+,K+-ATPase and Mg2+-ATPase activities by N-ethyl malemid on the form of curves of erythrocyte membranes amperometric titration by Ag+. It is shown that changes in a conformational structure of proteins membranes under the influence of detergents results in the transformation of SH-group of type I to SH-groups of type II. A 70% fall of Na+,K+-ATPase activity has the same result. So, the form of the curves for titration of erythrocyte membranes sulphydryl groups may serve as an indicator to the morpholocial and functional state of the membranes protein part.
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PMID:[Influence of detergents and inhibition of Na+,K+-ATPase and Mg2+ATPase on erythrocyte membrane SH-groups]. 14 2

The regulation of adrenergic receptors in rat heart was measured in rats made hyperthyroid by injection with thyroxine and made hypothyroid by addition of propylthiouracil to the drinking water. Hyperthyroid rats display cardiac hypertrophy and a decrease in epididymal fat pad weight. The maximal beta-receptor level of ventricular membranes, as determined by (-)-[3H]dihydroalprenolol binding, was increased 60% by thyroxine treatment and decreased about 30% by propylthiouracil treatment. The affinity of the beta receptor was unchanged after thyroxine or propylthiouracil treatment. The maximal activity of the isoproterenol-stimulated adenylate cyclase (EC 4.6.1.1) varied with thyroid state in a manner parallel to the increase in beta-adrenergic binding sites. Thyroxine treatment also increases by 2-fold the beta receptors in isolated rat fat cells. Propylthiouracil treatment lowered the level of alpha receptors in heart by 30% as measured by [3H]dihydroergocryptine binding, but increased the affinity about 2.5-fold. The highest level of alpha receptors was seen in control hearts. These studies indicate that thyroxine may control the turnover of beta-adrenergic receptors in heart and fat cells and regulate physiological responses in these tissues via a hormone-hormone interplay system. Thyroxine treatment reduced the activity of the membrane-bound Mg2+-ATPase (EC 3.6.1.3) and 5'-mononucleotidase (EC 3.1.3.5) but appears to increase the activity of the (Na+ + K+)ATPase (EC 3.6.1.4).
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PMID:Hormone action at the membrane level. VIII. Adrenergic receptors in rat heart and adipocytes and their modulation by thyroxine. 14 63

The influence of sulfhydryl reagents on ATPase systems of rabbit sceletal muscles nuclei was studied. It is found that p-ChMB at low concentration similarly inhibits both Mg2+- and Mg2+, Ca2+-ATPases. p-ChMB at higher concentrations inhibits completely Mg2+, Ca2+-ATPase, while Mg2+- ATPase--only by 60%. N-EM is lesser specific inhibitor of SH-groups, than p-ChMB. The degree of nuclear ATPases inhibition by N-EM is practically identical. Using inhibitory analysis, two hypes of skeletal muscles nuclei SH-groups are found: easily reacting with N-EM, and those reacting with N-EM at more high concentrations, which are essential for ATPase ATP-hydrolysing activity. ATP defends Mg2+, Ca2+-ATPase, but not the Mg2+-ATPase from N-EM inhibitory action. Cysteine completely eliminates the inhibitory effect of p-ChMB on Mg2+-ATPase but only 40% on MG2+, Ca2+-ATPase. Mg2+, Ca2+-ATPase of nuclei is more sensitive to the sulfhydryl venoms action than Mg2+-ATPase.
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PMID:[Effect of SH-reagents on ATPase systems of rabbit skeletal muscle nuclei]. 14 67

The effects of K+ and Na+ on the Ca2+,Mg2+-ATPase of sarcoplasmic reticulum fragments (SRF) were investigated at 1 mM ATP. There was an alteration of the sensitivity of the ATPase to the monovalent cations during storage of the SRF preparation. The Ca2+, Mg2+-ATPase of freshly prepared SRF was slightly activated by 5-10 mM K+ and Na+. Mg2+-ATPase was inhibited by both the monovalent cations to the same extent, and this response to the ions was independent of the freshness of the preparations. After storage of SRF, however, the Ca2+,Mg2+-ATPase was markedly activated by higher concentrations of K+ and Na+ (0.2-0.3 M). K+ and Na+ reduced the Ca uptake at the steady state in freshly prepared SRF, but did not affect pre-steady state uptake. In the presence of oxalate, the rate of Ca accumulation both in fresh and stored preparations was activated by 0.1-0.2 M K+ and Na+. The Ca2+, mg2+-ATPase with oxalate, so-called "extra ATPase," showed the same response to the ions as did the activity without oxalate during storage.
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PMID:The effects of storage of sarcoplasmic reticulum fragments on the Ca2+, Mg2+-ATPase. 14 89

Myosin has been isolated from baby hamster kidney cells (BHK21/C13) in high yield and characterized biochemically and immunologically. The subunit composition consists of 2 heavy chains, approximately 200,000 Daltons each, and 2 classes of light chains of approximately 16,000 and 20,000 Daltons. The myosin exhibits ATPase activity in the presence of K+-EDTA or Ca2+ but very little activity with Mg2+-ATP. The Mg2+-ATPase activity is stimulated only about 2-fold by skeletal actin, but a much larger activation is obtained in the presence of a protein kinase isolated from chicken gizzard. The increase in actin activation is accompained by the phosphorylation of the 20,000-Dalton light chain. BHK21 myosin is insoluble at low ionic strength and forms typical biopolar thick filaments. A specific antiserum generated against this protein forms a single precipitin line with the antigen but does not crossreact with either skeletal or smooth muscle myosin. The antiserum also specifically stains stress fibres in BHK21 cells as shown by indirect immunofluorescence.
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PMID:BHK21 myosin: isolation, biochemical characterization and intracellular localization. 14 98

Representatives of eleven different classes of isoquinoline alkaloids inhibit Na+, K+-ATPase and Mg2+-ATPase in rat brain microsomal preparations. In most cases the Na+, K+-ATPase is more sensitive than Mg2+-ATPase to inhibition by the alkaloids. The classes of alkaloids can be ranked according to potency of inhibition of Na+, K+-ATPase. Protoberberines are most effective, followed in decreasing order by benzophenanthridines, benzylisoquinolines, aporphines, tetrahydroprotoberberines, pavines, protopines, isoquinolines, tetrahydrobenzylisoquinolines, morphinanes, and tetrahydroisoquinolines. As specific representatives of each of the first four classes of alkaloids, berberine, sanguinarine, papaveroline and 1,2,10,11-tetrahydroxyaporphine, respectively, prove most valuable in kinetic studies because they exhibit the greatest inhibitory action on brain Na+, K+-ATPase. Kinetic analyses plotted in double reciprocal form reveal that berberine and 1,2,10,11-tetrahydroxyaporphine are simple linear competitive inhibitors with respect to ATP, whereas sanguinarine and papaveroline are simple linear noncompetitive inhibitors. These four representative alkaloids exhibit non-linear competitive inhibition with respect to Na+-activation. Additionally, these alkaloids significantly inhibit rat brain microsomal K+-activated pNPPase. The results demonstrate that certain members of several classes of isoquinoline alkaloids markedly affect various cation-dependent phosphohydrolases in vitro.
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PMID:Isoquinoline alkaloids. Inhibitory actions on cation-dependent ATP-phosphohydrolases. 14 28


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