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. The specific activity of the membrane-bound ATPase of Streptococcus cremoris HA was 1.30 mumol Pi/mg protein/min. 2. Km for ATP as substrate was 0.8 mM. 3. The pH optimum was 8.0 at +37 degrees C. 4. The ATPase was maximally activated with Mg2+/ATP molar ratio of 1:2. 5. Cations activated the enzyme in order: Mg2+ greater than Co2+ greater than Mn2+ greater than Zn2+ greater than Ca2+ greater than K+ greater than Na+. 6. The enzyme was inhibited by oligomycin (27-77%), sodium azide (13-33%) and ouabain (15-22%). N,N'-dicyclohexylcarbodiimide had no effect on the enzyme activity.
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PMID:Properties of the N,N'-dicyclohexylcarbodiimide resistant ATPase of Streptococcus cremoris. 295 54

The (Ca2+ + Mg2+)-ATPase from skeletal muscle sarcoplasmic reticulum was reconstituted into phospholipid bilayers. The permeability of lipid bilayers to Co2+ and glucose was increased slightly by incorporation of the ATPase, and the permeability of mixed bilayers of phosphatidylethanolamine and phosphatidylcholine increased with increasing content of phosphatidylethanolamine both in the presence and absence of the ATPase. The presence of the ATPase, however, resulted in a marked increase in permeability to Ca2+, the permeability decreasing with increasing phosphatidylethanolamine content. Permeability to Ca2+ was found to be dependent on pH and the external concentrations of Mg2+ and Ca2+, was stimulated by adenine nucleotides but was unaffected by inositol trisphosphate. A kinetic model is presented for Ca2+ efflux mediated by the ATPase. It is shown that the kinetic parameters that describe Ca2+ efflux from vesicles of sarcoplasmic reticulum also describe efflux from the vesicles reconstituted from the purified ATPase and phosphatidylcholine. It is shown that the effects of phosphatidylethanolamine on efflux can be simulated in terms of changes in the rates of the transitions linking conformations of the ATPase with inward- and outward-facing Ca2+-binding sites, and that effects of phosphatidylethanolamine on the ATPase activity of the ATPase can also be simulated in terms of effects on the corresponding conformational transitions. We conclude that the ATPase can act as a specific pathway for Ca2+ efflux from sarcoplasmic reticulum.
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PMID:A fast passive Ca2+ efflux mediated by the (Ca2+ + Mg2+)-ATPase in reconstituted vesicles. 295 21

The photoprobe 3'(2')-O-(4-benzoyl)benzoyladenosine 5'-triphosphate (Bz2ATP) was used to characterize the nucleotide-binding site of myosin subfragment 1 (SF1). Improved synthesis and purification of Bz2ATP are reported. 1H NMR and ultraviolet spectroscopy show that Bz2ATP is a 60:40 mixture of the 3'(2')-ribose isomers and that the epsilon M261 is 41,000 M-1 cm-1. Bz2ATP is hydrolyzed by SF1 comparably to ATP in the presence of actin or K+, NH4+, or Mg2+ ions; and the product, Bz2ADP, has a single binding site on SF1 (K'a = 3.0 X 10(5) M-1). [3H]Bz2ATP was photoincorporated into SF1 with concomitant loss of K+-EDTA-ATPase activity. Analysis of photolabeled SF1 showed that the three major tryptic peptides (23, 50, and 20 kDa) of the heavy chain fragment and the alkali light chains were labeled. The presence of ATP during irradiation protected only the 50-kDa peptide, indicating that the other peptides were nonspecifically labeled. If Bz2ATP was first trapped on SF1 by cross-linking the reactive thiols, SH1 and SH2, with p-phenylenedimaleimide, only the 50-kDa tryptic peptide was labeled. These results confirm and extend previous observations that [3H]Bz2ATP trapped on SF1 by cobalt(III) phenanthroline photolabeled the same 50-kDa peptide (Mahmood, R., and Yount, R.G. (1984) J. Biol. Chem. 259, 12956-12959). Thus, the 50-kDa peptide is labeled with or without thiol cross-linking, indicating that the relative position of SH1 and SH2 does not affect the labeling pattern.
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PMID:The interaction and photolabeling of myosin subfragment 1 with 3'(2')-O-(4-benzoyl)benzoyladenosine 5'-triphosphate. 295 59

Plasmodium falciparum digestive vacuoles containing ferric oxide granules were purified from parasite homogenates by centrifugation on discontinuous sucrose gradients. Digestive vacuole membranes prepared by osmotic lysis and washed with KCl showed no detectable contamination by erythrocyte membrane proteins and only minimal contamination by non-vacuolar parasite proteins. Purified vacuolar membranes were 2.6-fold enriched in total parasite membrane ATPase activity. This ATPase was optimally active at pH 7 in the presence of at least 2 mM Mg2+. Ca2+ and Mn2+ were approximately 80-90% as effective as Mg2+, and Zn2+, Co2+ and Fe2+ also exerted some stimulatory effect. The vacuolar membrane also hydrolyzed GTP, UTP, CTP and ADP, but AMP and 3',5'-cyclic AMP were hydrolyzed only one-tenth as effectively as ATP. The ATPase was unaffected by vanadate, ouabain or oligomycin but was significantly inhibited by the proton pump inhibitors NEM and NBD-Cl. Of 6 antimalarial drugs tested, quinine and quinacrine were the most effective inhibitors and mefloquine was the least effective.
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PMID:Purification of Plasmodium falciparum digestive vacuoles and partial characterization of the vacuolar membrane ATPase. 297 31

Ultraviolet irradiation above 300 nm of the stable MgADP-orthovanadate (Vi)-myosin subfragment 1 (S1) complex resulted in covalent modification of the S1 and in the rapid release of trapped MgADP and Vi. This photomodified S1 had Ca2+ATPase activity 4-5-fold higher than that of the non-irradiated control S1, while the K+EDTA-ATPase activity was below 10% of controls. There was a linear correlation between the activation of the Ca2+ATPase and the release of both ADP and Vi with irradiation time. Analysis of the total number of thiols and the ability of photomodified S1 to retrap MgADP by cross-linking SH1 and SH2 with various bifunctional thiol reagents indicated that the photomodification did not involve these reactive thiols. Irradiation of the S1-MgADP-Vi complex caused a large increase in absorbance of the enzyme at 270 nm which was correlated with the release of Vi from the active site, suggesting an aromatic amino acid(s) was (were) involved. However, analysis by three different methods showed no loss of tryptophan. All the irradiation-dependent phenomena could be prevented by replacing Mg2+ with either Co2+, Mn2+, or Ni2+. Unlike previous irradiation studies of Vi-dynein complexes [Lee-Eiford, A., Ow, R. A., & Gibbons, I. R. (1986) J. Biol. Chem. 261, 2337-2342], no peptide bonds were cleaved in photomodified S1. Photomodified S1 was able to retrap MgADP-Vi at levels similar to unmodified S1. Upon irradiation of the photomodified S1-MgADP-Vi complex, MgADP and Vi were again released from the active site, resulting in heavy chain cleavage to form NH2-terminal 21-kDa and COOH-terminal 74-kDa peptides. All evidence indicates that this new photomodification and subsequent chain cleavage occur specifically at the active site.
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PMID:UV-induced vanadate-dependent modification and cleavage of skeletal myosin subfragment 1 heavy chain. 1. Evidence for active site modification. 297 86

In the presence of Mg2+ the ecto-(nucleoside diphosphatase) on intact vascular endothelial or smooth muscle cells in culture selectively catabolizes the PS diastereoisomer of adenosine 5'-[alpha-thio]diphosphate, (PS)-ADP [alpha S], and the ecto-(nucleoside triphosphatase) selectively catabolizes the PS isomer of adenosine 5'-[beta-thio]triphosphate, (PR)-ATP[beta S], but exhibits no selectivity towards ATP[alpha S] isomers. In the presence of Cd2+ selectivity to ADP[alpha S] and to ATP[beta S] isomers is reversed; in the presence of Co2+, selectivity is lost. We conclude that each enzyme preferentially recognises the lambda (screw-sense) bidentate Mg(II)-nucleotide complex at its active site.
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PMID:Investigation of the preferred Mg(II)-adenine-nucleotide complex at the active site of ectonucleotidases in intact vascular cells using phosphorothioate analogues of ADP and ATP. 299 64

The localization of leukotriene D4-metabolizing enzyme on the cell surface was examined using human neutrophils. Intact neutrophils rapidly converted leukotriene D4 to leukotriene E4. However, when neutrophils were modified chemically by diazotized sulfanilic acid, a poorly permeant reagent which inactivates cell surface enzymes selectively, the leukotriene D4-metabolizing activity of neutrophils decreased significantly without any inhibition of the cell viability or marker enzymes of cytosol, granules, microsome and mitochondria. The leukotriene D4-metabolizing enzyme activity of the membrane fraction was inhibited by modification to the same extent as that of Mg2+-dependent ATPase, a cell-surface marker enzyme. Among various enzyme inhibitors examined, a metal chelator, o-phenanthroline, strongly suppressed the leukotriene D4-metabolizing activity of intact neutrophils and the o-phenanthroline-inactivated enzyme activity was fully reactivated by Co2+, Mn2+ and Zn2+. These results would suggest that some metalloenzyme located on the cell surface is involved in the conversion of leukotriene D4 to leukotriene E4 by neutrophils.
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PMID:Localization of leukotriene D4-metabolizing metalloenzyme on the cell surface of human neutrophils. 301 21

Ferrous iron uptake studies in Bifidobacterium bifidum var. pennsylvanicus were carried out in a well-defined salt solution termed "modified Hanks solution" at both high iron concentrations (LAFIUS conditions) and low concentrations (HAFIUS conditions). Various divalent metals, Mn2+, Zn2+, Ni2+ and Cu2+, inhibited iron uptake under HAFIUS conditions in a non-competitive manner, and in a pseudo-competitive manner under LAFIUS conditions. Cr2+ had no effect. Co2+ inhibited iron uptake competitively under HAFIUS conditions. Metabolic affectors that inhibited iron uptake both under HAFIUS and LAFIUS conditions were: tetraphenylphosphonium chloride, diethylstilbesterol, vanadate, carbonylcyanide-m-chlorophenyl-hydrazone, and a mixture of valinomycin and nigericin. Substances that stimulated iron uptake were KCl, valinomycin, and nigericin. Iron uptake under LAFIUS conditions in piperazine-buffered modified Hanks solution was higher than that in the acetate-buffered solution, and acetate inhibited iron uptake in the piperazine buffer. HAFIUS showed no difference. It is concluded that iron uptake in bifidobacteria is driven by an ATPase-dependent proton-motive force and that both the pH gradient and membrane potential are involved in this process. Mn2+, Zn2+, Ni2+, and Cu2+ may be transported via LAFIUS, but not HAFIUS. HAFIUS may transport only Co2+ in addition to Fe2+.
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PMID:Ferrous iron uptake by Bifidobacterium bifidum var. pennsylvanicus: the effect of metals and metabolic inhibitors. 303 34

The addition of nanomolar concentrations of free Fe2+, Mn2+, or Co2+ to rat liver plasma membranes resulted in an activation of ATP hydrolysis by these membranes which was not additive with the Ca2+-stimulated ATPase activity coupled to the Ca2+ pump. Detailed analysis showed that, if fact, (i) as for the stimulation of (Ca2+-Mg2+)-ATPase by Ca2+, activation of ATP hydrolysis by Fe2+, Mn3+, or Co2+ followed a cooperative mechanism involving two ions; (ii) two interacting sites for ATP were involved in the activation of both Fe2+- and Ca2+-stimulated ATPase activities; (iii) micromolar concentrations of magnesium caused the same dramatic inhibition of both activities; and (iv) the subcellular distribution of Fe2+-activated ATP hydrolysis activity corresponded to that of plasma membrane markers. This suggests that the (Ca2+-Mg2+)-ATPase might be stimulated not only by Ca2+, but also by Fe2+, Mn2+, or Co2+. However, interaction of (Ca2+-Mg2+)-ATPase with Fe2+, Mn2+, or Co2+ inhibited the Ca2+ pump activity. Furthermore, neither the formation of the phosphorylated intermediate of (Ca2+-Mg2+)-ATPase, nor ATP-dependent (59Fe) uptake could be detected in the presence of Fe2+ concentrations which stimulated ATP hydrolysis. We conclude that: (i) under the influence of certain metal ions, the Ca2+ pump in the liver plasma membrane may be switched to an uncoupled state which displays ATP hydrolysis activity, but does not insure ion transport; (ii) therefore the Ca2+ pump in liver plasma membranes specifically insures Ca2+ transport.
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PMID:Fe2+ and other divalent metal ions uncouple Ca2+ transport from (Ca2+-Mg2+)-ATPase in rat liver plasma membranes. 315 30

Properties of the anion ATPase from rat red blood cell membranes were investigated. Diethyl ether treated membranes exhibited the increased activity of the anion ATPase. Na+, K+- and Ca2+-ATPase activities were not found in these preparations. The pH optimum of the anion ATPase was at pH 8.5. The enzyme was stimulated by methanol and inhibited by glycerol. Among the inorganic anions stimulators, inhibitors and indifferent substances were observed. Anions of thiocyanate, sulfite and bicarbonate altered noncompetitively the ATPase activity. Sulfite stimulated and thiocyanate inhibited the ATP hydrolysis in presence of magnesium, calcium, zinc, cobalt, manganese and nickel. Reactions with ATP, ITP, GTP but not with ADP and AMP used as substrates were sensitive to sulfite and thiocyanate. EGTA did not change the stimulation and inhibition effects of the anions on the ATPase activity. The similarity of properties of erythrocyte and mitochondrial ATPases is discussed.
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PMID:[Properties of erythrocyte anion ATPase]. 315 65


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