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)

The distribution of a lipophilic spin probe, 5-doxyl stearate, between the inner and outer halves of the sarcoplasmic reticulum (SR) bilayer was determined by titration with Ni X EDTA, a spin broadening agent. Titrations were also performed with Fe(CN)3-6 and with the solvated Ni2+ cation. Ni X EDTA titrations reached a clearly defined asymptote at 35% signal reduction. Fe(CN)3-6 and Ni2+ titrations gave biphasic curves but showed 35% of the signal to be readily eliminated at low concentrations. When the Ni2+ cation was used with ionophore, titrations indicated that 96% of the probe is aligned in the bilayer with the spin moiety at either the inner or outer interface. It was concluded that the spin probe distribution between the outer and inner halves of the SR bilayer is 35:65, respectively. Titrations performed on vesicles of purified SR lipids gave a ratio of 60 exposed:40 protected, consistent with the vesicular geometry. In addition the spin probe distribution in SR vesicles did not vary as a function of temperature, salt concentration, or spin probe concentration. On this basis it was concluded that the spin probe distribution gives a reasonable estimation of the volume of fluid lipids available to readily solubilize the probe in each half of the bilayer and that the observed asymmetry in distribution is due to the presence of SR proteins which were eliminated in the pure lipid vesicles. Furthermore, as EDTA is unique in its ability to chelate transition metals, Ca2+ and EGTA can be used in Ni X EDTA titrations without altering the chelation of Ni2+. Known changes in ATPase conformation accompanying Ca2+ and adenyl-5'-yl imidodiphosphate X Mg binding did not affect the spin probe distribution. However, phosphorylation of the enzyme by Pi gave a small, but clearly discernible, protection of spin probe signal. Chemical reduction with ascorbate indicated that this was due to occlusion of a small fraction of spin probes and thus possibly SR lipids.
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PMID:Distribution of a fatty acid spin probe in sarcoplasmic reticulum. Evidence of membrane asymmetry. 298 78

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

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

The mechanism of nickel transport by Clostridium pasteurianum was investigated by using 63NiCl2 and a microfiltration transport assay. Nickel transport was energy dependent, requiring either glucose or sucrose; xylose and o-methyl glucose did not support growth, butyrogenesis, or transport. Transport was optimum at pH 7 and 37 degrees C, and early-stationary-phase cells had the highest propensity for nickel transport. The apparent Km and Vmax for nickel transport approximated 85 microM Ni and 1,400 pmol of Ni transported per min per mg (dry weight) of cells, respectively. On the basis of metal specificity, nickel appears to be transported primarily by a magnesium transporter, although an alternative nickel transporter may also be involved. ATPase inhibitors (N,N'-dicyclohexylcarbodiimide, tributyltin chloride, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, and quercetin), protonophores (carbonyl cyanide m-chlorophenylhydrazone, 2,4-dinitrophenol, and gramicidin D), metal ionophores (valinomycin, monensin, and nigericin), benzyl viologen, carbon monoxide, and oxygen inhibited nickel transport. Nickel transport was coupled indirectly to butyrogenesis and was dependent on the energy state of the cell.
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PMID:Energy-dependent transport of nickel by Clostridium pasteurianum. 333 82

We studied 67 patients with multiple contact allergies to determine whether there was an association of this state with any particular HLA antigen. HLA-A, -B and DR antigens were typed by standard serological methods. There was no significant HLA association, although there was an increased frequency of DR4 in those patients who included nickel as one of their sensitivities (64% compared with 33% in controls), and an increase in DR6 in those patients who included sensitivity to a rubber accelerator (45% compared with 16% in controls). However, when the probabilities were corrected for the number of HLA antigens tested and the number of substances in the patch test battery, these associations were no longer statistically significant. We also examined the morphology and numbers of Langerhans cells in epidermal sheets from six subjects with multiple allergies. There were no differences in appearance or numbers of Langerhans cells stained for ATPase, compared with 20 non-allergic controls.
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PMID:HLA antigens and Langerhans cell density in contact dermatitis. 349 Aug 76

The effects of subcutaneous (s.c.) injections of magnesium acetate (MgAcet) on the acute toxicity of intraperitoneal (i.p.) nickelous acetate (NiAcet) were studied in rats. Male F344/NCr rats, 150-200 g body wt, received either NiAcet alone, MgAcet alone, or both. The dose of NiAcet was 115 mumol/kg body wt for the lethality and 95 mumol/kg body wt for all other tests. MgAcet was given in 400 mumol/kg body wt daily doses at -24, 0, and +24 h relative to NiAcet for the lethality study, or at -24 and 0 h for all other tests. Treatment with MgAcet increased 14-day survival of the NiAcet-injected rats (57% vs. 27%; P less than 0.02) and diminished 24-h nickel uptake in the lung (50%), liver (44%), and kidneys (30%), but not in blood, spleen, heart, or brain. MgAcet also increased (15% in 0-3 h) urinary excretion of nickel. It had no effect, however, on nickel-induced nephropathy, hyperglycemia, lipid peroxidation in liver and kidneys, and decrease in renal cytochrome P-450 content. Neither NiAcet nor MgAcet had any effect on the ATPase activity in heart and brain. These results suggest that MgAcet decreases the lethality of NiAcet by altering the pharmacokinetics of nickel(II) and not by enhancement of a pharmacodynamic tolerance to nickel(II).
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PMID:Effects of magnesium acetate on the toxicity of nickelous acetate in rats. 379 59

The effects of zinc on the enzymes of femoral tissue were investigated in weanling rats that had been given zinc sulfate (1.0 mg Zn2+/100 g body wt) p.o. for 3 days. Administration of zinc caused a marked elevation of alkaline phosphatase and acid phosphatase activities, whereas it did not cause significant changes in succinate dehydrogenase, 5'-nucleotidase, ATPase, pyrophosphatase and beta-N-acetylglucosaminidase activities. The effect of zinc was greater on alkaline phosphatase of the femoral diaphysis. Zinc content of the femoral diaphysis was raised significantly by administration of zinc. The addition of zinc in concentrations of 10(-2)-10(2) microM did not produce a significant increase in alkaline phosphatase activity in the femoral diaphysis, indicating that zinc could not activate the enzyme. Administration of cycloheximide or actinomycin D completely inhibited the increase in alkaline phosphatase activity produced by administration of zinc. DNA content of the femoral diaphysis, but not epiphysis, was increased markedly by administration of zinc. The increases in both alkaline phosphatase activity and DNA content of the femoral diaphysis were not caused by administration of copper, manganese, cobalt, nickel and chromium(III). The present investigation suggests that zinc may induce the increase in alkaline phosphatase related to DNA synthesis and, as a result, stimulate bone growth.
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PMID:Action of zinc on bone metabolism in rats. Increases in alkaline phosphatase activity and DNA content. 395 86

The key role of the Langerhans cell (LC) in the immune response and particularly in allergic contact dermatitis is well documented. At first, we determined in the epidermis of the forearm by a non-sensitized adult volunteer, the variations in the density of LC (number/mm2), following the application of various chemicals: nickel sulphate 5 p. 100; erythromycin base 2 p. 100, 2,4-dinitro-1-chlorobenzene (DNCB) 0.02 p. 100 in white petrolatum. Measurements were made at 6, 24 and 48 hours. In a second stage, the volunteer was sensitized to DNCB and a similar study was performed after application of DNCB 0.02 p. 100 at 6 and 24 hours. Normal skin was used as control. The epidermis was obtained by using the suction blister method: LC were identified by the enzymatic ATPase technique and by the immunocytological OKT6 technique. Surfaces were determined by means of a computerized digital tablet. Results obtained with the ATPase technique cannot be interpreted. The density of LC determined by the OKT6 is not significantly modified when the various chemicals are applied on the skin of the non-sensitized volunteer. After sensitization to DNCB, the number of LC is significantly increased after 6 hours of application of DNCB 0.02 p. 100 but not after 24 hours. Further studies are needed to confirm these preliminary observations.
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PMID:[Quantitative study of the number of Langerhans cells per surface unit in allergic contact eczema]. 409 5

The new technique of molecular cytochemitry (Taylor DL, Wang YL (1978): Proc Natl Acad Sci USA 75:857) requires the use of functional fluorescent analogs of cellular components with optimal fluorescence characteristics. An analog of actin suitable for this technique is prepared by reacting purified rabbit striated muscle actin with 5-iodoacetamidofluorescein (5-IAF). The conjugate is purified by DEAE-cellulose ion exchange chromatography and cycles of polymerization-depolymerization, yielding a relatively homogeneous product with the fluorescein group covalently attached to cystein 373. The fluorescently labeled actin maintains normal polymerizability and activates heavy meromyosin Mg2+ adenosine triphosphatase to the same extent as unlabeled actin. Furthermore, fluoresecent paracrystals are readily detectable in fluroescence microscope upon adding excess Mg2+ or Ni2+ ions. Spectrofluorimetric studies of the bound fluorescein indicate that the peak excitation and emission wavelengths, the shapes of the spectra, and the peak fluorescence intensities are somewhat sensitive to polymerization and heavy meromyosin binding. Possible causes of these spectral changes are analyzed and future applications of this fluorescently labeled actin in vitro as well as in vivo are discussed.
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PMID:Preparation and characterization of a new molecular cytochemical probe: 5-iodoacetamidofluorescein-labeled actin. 610 18

Rat heart sarcolemma was shown to hydrolyze ATP in the presence of Ca2+ or Mg2+; Ka values for Ca2+ and Mg2+ were in the range of 0.58-0.67 and 0.72-0.83 mM, whereas Vmax values were 33-38 and 21-28 mumol Pi/mg per hr, respectively. Both Ca2+ ATPase and Mg2+ ATPase showed low- and high-affinity sites for ATP; the Km value for the low-affinity sites for both enzyme activities was 300-325 microM, whereas Km values for high-affinity sites were 75-85 and 100-108 microM, respectively. The pattern of nucleotide hydrolysis in the presence of Ca2+ was found to be different from that with Mg2+. Although both high concentrations of ADP and Pi inhibited the enzyme activities, Mg2+ ATPase was more sensitive to ADP and less sensitive to Pi in comparison to Ca2+ ATPase. Storage of sarcolemma at about 0 degrees C showed a greater increase in ATP hydrolysis with Ca2+ than with Mg2+. The inhibitory effect of Mg2+ on Ca2+ ATPase, unlike that of Ni2+, Co2+, and Cu2+, was more than that on Mg2+ ATPase. Treatment of membranes with sodium dodecylsulfate or deoxycholate produced a greater reduction in Mg2+ ATPase than in Ca2+ ATPase. These results further support the view that Ca2+ ATPase and Mg2+ ATPase may be two separate enzymes in heart sarcolemma. It is suggested that Ca2+-dependent ATPase may be involved in opening calcium channels for the entry of calcium, whereas Mg2+ ATPase may serve as a Mg2+ pump mechanism for the efflux of magnesium from the cardiac cell.
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PMID:Properties of Ca2+- or Mg2+-dependent ATPase in rat heart sarcolemma. 613 31


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