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 intracellular pH was measured in growing Clostridium pasteurianum with and acid-base equilibrium distribution method. [14C]Dimethyloxazolidinedione, [14]methylamine and [14C]acetic acid were used as "deltapH-indicators". During growth the extracellular pH decreased from 7.1 to 5.1; simultaneously the intracellular pH changed from 7.5 to 5.9. Thus, the intracellular pH was more alkaline than the extracellular pH by 0.4 to 0.8 pH-units. 2. This pH gradient (interior alkaline) was abolished by the proton conductor carbonylcyanide m-chlorophenylhydrazone and the ATPase inhibitor N,N'-dicyclohexylcarbodiimide. The pH gradient could not be demonstrated in cells depleted of an energy substrate. These results suggest that the pH gradient is formed by an ATPase-driven extrusion of protons from the cells rather than by a Donnan potential. 3. Growth of the organism was inhibited by low concentrations of both carbonylcyanide m-chlorophenylhydrazone (5 muM) and dicyclohexylcarbodiimide (5 muM). This finding suggests that the pH gradient is essential for the growing cell as it may be required for substrate accumulation and other types of transport processes.
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PMID:The internal-alkaline pH gradient, sensitive to uncoupler and ATPase inhibitor, in growing Clostridium pasteurianum. 0 Feb 37

The purple membrane of Halobacterium halobium acts as a light-driven proton pump, ejecting protons from the cell interior into the medium and generating electrochemical proton gradient across the cell membrane. However, the type response of cells to light as measured with a pH electrode in the medium consists of an initial net inflow of protons which subsides and is then replaced by a net outflow which exponentially approaches a new lower steady state pH level. When the light turned off a small transient acidification occurs before the pH returns to the original dark level. We present experiments suggesting that the initial inflow of protons is triggered by the beginning ejection of protons through the purple membrane and that the initial inflow rate is larger than the continuing light-driven outflow. When the initial inflow has decreased exponentially to a small value, the outflow dominates and causes the net acidification of the medium. The initial inflow is apparently driven by a pre-existing electrochemical gradient across the membrane, which the cells can maintain for extended times in the absence of light and oxygen. Treatments which collapse this gradient such as addition of small concentrations of uncouplers abolish the initial inflow. The triggered inflow occurs through the ATPase and is accompanied by ATP synthesis. Inhibitors of the ATPase such as N,N'-dicyclohexylcarbodiimide (DCCD) inhibit ATP synthesis and abolish the inflow. They also abolish the transient light-off acidification, which is apparently caused by a short burst of ATP hydrolysis before the enzyme is blocked by its endogenous inhibitor. Similar transient inflows and outflows of protons are also observed when anaerobic cells are exposed to short oxygen pulses.
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PMID:Light-driven proton translocations in Halobacterium halobium. 0 22

Intact vacuoles were isolated from petals of Hippeastrum and Tulipa (Wagner G.J. and Siegelman, H.W. (1975) Science 190, 1298--1299). The ATPase activity of fresh vacuole suspensions was found to be 2--3 times that of protoplasts from the same tissue. 70--80% of the ATPase activity of intact vacuoles was recovered in tonoplast preparations. The antibiotic Dio-9 at 6mug/10(6) vacuoles or protoplasts causes 40% inhibition. However, only the protoplast ATPase is sensitive to oligomycin. N,N'-dicyclohexylcarbodiimide (DCCD) slightly stimulates ATPase activity in both vacuole and protoplast suspensions, whereas ethyl-3-(3-dimethylaminopropyl carbodiimide) (EDAC) strongly inhibits. Spectrophotometric studies show that in the petal the vacuolar contents have a pH of 4.0 for Tuplipa and 4.3 for Hippeastrum, whereas the intact isolated vacuole has an internal pH of 7.0 (in pH 8.0 buffer) for (Tulipa and about 7.3 for Hippeastrum. Internal ion concentrations of 150, 46, 30, 30 and 6 mM were found for K+, Na+, Mg2+, Cl-, and Ca2+ respectively, which are about the same as those in protoplasts.
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PMID:Membrane-bound ATPase of intact vacuoles and tonoplasts isolated from mature plant tissue. 1 30

Dicyclohexylcarbodiimide-resistant mutants of Escherichia coli were isolated and characterized In one mutant the unc genes and affects the membrane-integrated part of the ATP synthetase. The sensitivity of ATP synthetase functions to N,N' -dicyclohexylcarbodiimide was compared in wild-type and mutant membranes. The membrane-integrated part of the wild-type ATP synthetase is highly sensitive to ATP-dependent membrane energization and restoration of lactate-dependent energization of ATPase-depleted membranes. In mutant membranes this concentration has only a slight effect on these activities whereas a severe inhibition is obtained at 200 muM. Using the highly water-soluble 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide theactivities of wild-type and mutant membranes are inhibited to the same extent. TheATP synthetase of wild-type and mutant was partially purified and incorporated muM. Uinto liposomes. These showed an uncoupler-sensitive ATP-32Pi exchange and ATP-dependent quenching of acridine-dye fluorescence. The activities of mutant and wild-type proteoliposomes exhibit the same pattern of sensitivity to dicyclohexylcarbodiimide as the corresponding membranes.
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PMID:A mutant ATP synthetase of Escherichia coli with an altered sensitivity to N,N' -dicyclohexylcarbodiimide: characterization in native membranes and reconstituted proteoliposomes. 1 31

It has been proposed (Slayman, C.L., Long W.S., and Lu, C.Y.-H. (1973) J. Membr. Biol. 14, 305--338) that in Neurospora crassa, a plasma membrane ATPase functions to pump H+ ions out of the cell, thereby generating an electrochemical gradient that can drive transport processes. Using the concanavalin A method of Scarborough (Scarborough G.A. (1975)J. Biol. Chem. 250, 1106--1111), we have prepared plasma membranes of Neurospora and have deomonstrated that they do contain a distinct ATPase activity with the following properties. It has a pH optimum of 6.0, is highly specific for ATP (hydrolyzing other nucleoside triphosphates less than 6% as rapidly), requires Mg2+ at concentrations approximately equimolar to the concentration of ATP, is weakly stimulated by certain monovalent cations (K+ and NH4+) and anions (SCN- and acetate), is inhibited by N,N'-dicyclohexylcarbodiimide, but is not affected by oligomycin or ouabain. The plasma membrane fraction also contains residual mitochondrial contamination, which can be determined quantitatively by assaying oligomycin-sensitive ATP-ase activity, at pH 8.25, and succinic dehydrogenase activity.
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PMID:Characterization of plasma membrane adenosine triphosphatase of Neurospora crassa. 1 97

The N,N'-dicyclohexylcarbodiimide-binding proteolipid from lettuce chloroplast membranes has been purified by a novel, rapid technique involving I-butanol extraction and ether precipitation. Reconstitution of this proteolipid into liposomes composed of chloroplast lipids and subsequent incorporation of bacteriorhodopsin resulted in the formation of liposomes exhibiting a light-dependent accumulation of protons. This accumulation was significantly enhanced upon addition of N,N'-dicyclohexylcarbodiimide at concentrations similar to those that inhibit chloroplast adenosinetriphosphatase activity. Radioactively labeled N,N'-dicyclohexylcarbodiimide was found to be incorporated essentially into the proteolipid of the reconstituted liposomes. These results suggest that the functional unit responsible for proton channeling in the chloroplast membrane has been isolated and reconstituted in the native state.
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PMID:Isolation of a chloroplast N,N'-dicyclohexylcarbodiimide-binding proteolipid, active in proton translocation. 1 36

Proton translocating ATPase of oxidative phosphorylation was divided into three functional units: pump, channel, and gate. This was achieved by the use of highly stable pure ATPase obtained from a thermophilic bacterium PS3. The pump and gate were found in a catalytic moiety of the ATPase called TF1, and the channel was in the remaining hydrophobic moiety of the ATPase called TF0 which rendered TF1 sensitive to energy transfer inhibitor such as DCCD. TF1 was composed of five subunits (alpha, 56,000; beta, 53,000; gamma, 32,000; delta, 15,500; epsilon, 11,000 daltons). The essential component of the pump was beta-subunit, since beta gamma-complex or alpha beta delta-complex showed ATPase activity. The gate which blocked passive leakage of protons through TF0 in the proteoliposomes was shown to be gamma delta epsilon-complex in TF1. Both delta- and epsilon-subunits were required to connect alpha beta gamma-complex to TF0. TF0 was identical to the channel and was composed of three kinds of subunits (19,000, 13,500, and 5,400 daltons) and the smallest one was [14C]-DCCD binding protein. When the ATPase was incorporated into vesicles containing highly stable saturated branched phospholipids, ATP-driven electrochemical potential of proton (delta mu H+ = 253mV) and proton gradient driven net synthesis of ATP were demonstrated. For these activities, pump, channel, and gate of proton translocating ATPase were all required.
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PMID:Proton translocating ATPase: its pump, gate, and channel. 2 68

Mutants of Bacillus megaterium displaying malate-driven ATP synthesis resistant to uncouplers of oxidative posphorylation are further characterized. Both the pH gradient and electrical potential generated across the membrane by malate respiration are equally sensitive to uncouplers in the wild type and uncoupler-resistant mutants. The mutants possess 0 to 10% of the wild type ATPase activity which is not activated by pretreatment with heat or trypsin. Despite this inability to measure ATPase activity, the mutants demonstrate acid-pulse-driven ATPase synthesis which is sensitive to uncouplers as well as malate-driven ATP synthesis which becomes uncoupler sensitive at pH 5.5. N,N' -Dicyclohexylcarbodiimide and valinomycin plus potassium inhibition of ATP synthesis is reversed by uncouplers in the mutants but not in the wild type. The data support the existence of a specific site on the ATPase complex for uncoupler binding which, if altered by mutation, affects uncoupler binding to the complex. The retention of malate-driven ATP synthesis in the absence of a significant pH gradient or electrical potential suggests that an alternative intermediate is involved in coupling oxidation to phosphorylation.
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PMID:Membrane bioenergetic parameters in uncoupler-resistant mutants of Bacillus megaterium. 2 41

ATP-driven transport and accumulation of epinephrine in chromaffin granule membrane vesicles isolated from bovine adrenal medulla is inhibited by the proton ionophores carbonylcyanide p-trifluoromethoxyphenylhydrazone and nigericin, but not by valinomycin. Moreover, an artificially imposed pH gradient (interior acid) is able to drive this reserpine-sensitive transport system in the absence of ATP. Dicyclohexylcarbodiimide, an inactivator of the chromaffin granule membrane-bound ATPase, completely inhibits ATP-dependent epinephrine accumulation, but has much less effect when an imposed pH gradient is the driving force for epinephrine transport. The findings provide a strong indication that a pH gradient (interior acid) is the immediate driving force for epinephrine uptake in these storage granules and suggest that ATP-driven epinephrine transport is the result of two processes: (i) generation of a proton electrochemical gradient (interior acid and positive) by the membrane-bound, proton-translocating ATPase; and (ii) pH gradient-driven accumulation of the catecholamine.
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PMID:Role of a transmembrane pH gradient in epinephrine transport by chromaffin granule membrane vesicles. 2 92

ATPase was detected in the membranes of a motile Streptococcus. Maximal enzymic activity was observed at pH 8 and ATP/Mg2+ ratio of 2. Mn2+ and Ca2+ could replace Mg2+ to some extent. Besides ATP, GTP and ITP were substrates. The enzyme was inhibited by N,N'-dicyclohexylcarbodiimide but not by sodium azide, uncouplers or bathophenanthroline. An electrochemical gradient of protons, which was artificially imposed across the membranes of Streptococcus cells by manipulation of either the K+ diffusion potential or the transmembrane pH gradient, led to ATP synthesis. ATP synthesis was abolished by proton conductors, an inhibitor of the ATPase or an increase in the extracellular K+ concentration. A comparison between the phosphate potential and the electrochemical proton gradient showed that the data found are in agreement with a stoichiometry of 2 protons translocated per molecule ATP synthesized.
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PMID:Hydrolysis and synthesis of ATP by membrane-bound ATPase from a motile Streptococcus. 3 Nov 47


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