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)

A soluble Mg-dependent ATPase, similar to the mitochondrial ATPase from beef heart, has been isolated from heart mitochondria of salmon (Salmo salar). The salmon heart ATPase has 5 subunits with molecular weights similar to the beef heart enzyme, but the Stoke's radius of the intact salmon enzyme is larger. The salmon heart ATPase is less temperature labile than the beef heart enzyme. The salmon heart ATPase is strongly inhibited by ADP, and the inhibition is highly temperature dependent. The ITPase activity is also inhibited by IDP (Ki = 180 micron). 2,4-Dinitrophenol in small concentrations stimulates the ITPase activity as well as the ATPase activity of the "washed" salmon heart enzyme. However, in an enzyme preparation which had been freed of most of the bound nucleotides by dialysis in the presence of glycerol (Roveri et al., 1980) the ITPase activity is not stimulated by 2,4-dinitrophenol.
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PMID:Some properties of isolated mitochondrial ATPase from salmon heart. 615 Aug 4

The lysolecithin extraction procedure originally described by Sadler et al. (1974) has been modified to yield a H+-ATPase with high levels of Pi-ATP exchange activity (400-600 nmol x min-1 x mg-1). This activity is further enhanced (1400-1600 nmol x min-1 x mg-1) following sucrose density gradient centrifugation in the presence of asolectin. This enhancement results in part from a lipid-dependent activation and in part from removal of inactive complexes. The H+ translocating activity of the complex has been determined spectrophotometrically using binding of oxonol VI as an indicator of membrane potential. Pi-ATP exchange, ATP hydrolysis, and oxonol binding are sensitive to energy-transfer inhibitors (oligomycin, rutamycin) and/or uncouplers (DNP, FCCP).
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PMID:Isolation of a highly active H+-ATPase from beef heart mitochondria. 621 3

To investigate the mechanism by which various biological action of licorice root are brought about, the effects of echinatin as a small constituent of Glycyrrhiza echinata and several related compounds on mitochondrial energy transfer reactions were examined. The results obtained were as follows: 1) Echinatin, 4'-hydroxychalcone, chalcone and 3,4'-dihydroxychalcone at a low concentration cause deterioration of respiratory control and oxidative phosphorylation of isolated rat liver mitochondria. 2) Chalcone and 4'-hydroxychalcone stimulate both latent and DNP-ATPase activity of mitochondria. Echinatin inhibits DNP-ATPase activity while stimulating range latent ATPase activity in the low concentration. 3) Chalcone and 4'-hydroxychalcone induce a rapid potassium release from mitochondrial vesicles, while echinatin and 3,4'-dihydroxychalcone have lesser effect than the former two substances. From these results, it can be concluded that echinatin and several related compounds disturb the mitochondrial energy transfer reactions and membrane permeability.
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PMID:The effects of echinatin and its related compounds on the mitochondrial energy transfer reaction. 622 Nov 18

Adenosine phosphate and creatine phosphate amount was determined in the brain tissue of 3-4-week, 6-8 month and 26-26 month old mongrel female rats. The maximum ATP and creatine phosphate amount and the minimum of ADP and AMP were found in young rats. In adult rats as compared with the young the ATP amount is the same, the ADP and AMP level rises, that of creative phosphate falls and energy charge decreases. In the brain of old rats the ATP and ADP amount falls, that of creatine phosphate and AMP remains at the level of mature-age animals. Despite a decrease in the ATP amount in the brain at the old age, the Mg, DNP- ATPase activity of mitochondria isolated from brain cortex and stem of the old rats remains at the level typical of adult animals.
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PMID:[High energy phosphate compounds and ATPase activity of mitochondria in the brain of rats of different ages]. 622 20

The dog tracheal epithelium actively secretes Cl and absorbs Na. The possible dependency of this electrolyte transport on a Mg-dependent, Na-K-activated adenosine triphosphatase (Na-K-ATPase, EC 3.6.1.3) was examined. The characteristics of this enzyme system were investigated using homogenates of tracheal epithelium. The electrical properties and ion fluxes of this epithelium were determined in tissues mounted in Ussing chambers. Addition of Na and K produced an approximate 50% activation of basal Mg-ATPase activity. The apparent Km values for ATP, Na, K, and Mg were 0.4, 12.7, 1.9, and 1.6 mM, respectively. The total specific ATPase activity was 8.1 +/- 0.4 and that of the Mg-ATPase 4.3 +/- 0.1 mumol Pi. mg protein -1.h-1. Addition of ouabain (1 muM) or omission of K from the submucosal bathing solution reduced potential difference (PD) and short-circuit current (SCC) significantly. Relatively low concentrations (0.1 mM or less) of ethacrynic acid, furosemide, or 2,4-dinitrophenol (2,4-DNP) depressed SCC and PD significantly, i.e., at concentrations that were without effect on the Na-K-ATPase activity. Ethacrynic acid inhibited Cl secretion, whereas 2,4-DNP lowered both Na and Cl transport. These data demonstrate that 1) the tracheal mucosa of dogs contains a Na-K-ATPase at relatively high specific activity, 2) this enzyme is likely contained in the basal aspect of this membrane, 3) it appears to be essential for maintenance of Cl secretion, and 4) Cl secretion can be reduced (by ethacrynic acid, furosemide, and 2,4-DNP) without Na-K-ATPase inhibition.
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PMID:Characterization of Na-K-ATPase in dog tracheal epithelium: enzymatic and ion transport measurements. 624

Gladiolic acid (GA, 4-methoxy-5-methyl-0-phthalaldehyde-3-carboxylic acid), an antifungal aromatic ortho dialdehyde produced by Penicillium gladioli was found to be a potent inhibitor of electron transport and oxidative phosphorylation reactions in sweet potato and mung bean mitochondria. Similar results were also found with the naturally occurring ortho dialdehydes, cyclopaldic acid, quadrilineatin, and flavipin as well as the synthetic dialdehydes, 3-formyl opianic acid and 0-phthalaldehyde. Because of their highly reactive ortho-diformyl grouping, GA and structurally related dialdehydes apparently act as multisite inhibitors affecting electron transport and oxidative phosphorylation (at each coupling site). Gladiolic acid has no uncoupling effect like 2,4-dinitrophenol and does not have the same point of interaction in the energy transfer process as oligomycin. Several "partial" reactions of phosphorylation (Mg+2-DNP-stimulated ATPase; ATP-Pi exchange) were strongly inhibited by the various dialdehydes. Flavipin and quadrilineatin are potent inhibitors (80% at a concentration of 25 microM) of site III phosphorylation. Gladiolic acid and related ortho dialdehydes inactivate the catalytic activity of native cytochrome c in vitro. Lysyl epsilon-NH2 rich cytochrome c may be a major site of GA action in the intact mitochondrion. In view of the high chemical reactivity of the orthodiformyl group, it is suggested that mitochondrial function may be affected by aromatic ortho dialdehydes through a combination of reactions involving cross-linking of amino groups on membrane polypeptides and monofunctional reaction with free amino groups important for enzyme function, including epsilon-NH2 groups on cytochrome c. Cross-linking in mitochondrial membrane systems might affect function by interfering with molecular motion in the operation of the terminal portion of the electron-transport chain. The primary toxicological mode of action of GA and related dialdehydes appears to be due to inhibition of mitochondrial function.
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PMID:Inhibition of electron transport and oxidative phosphorylation in plant mitochondria by gladiolic acid and structurally-related aromatic ortho dialdehydes. 624 81

The efflux of adenine nucleotides from three human tumor mitochondria has been investigated with mitochondria prelabeled with radioactive ATP. Uncouplers induce a large efflux of adenine nucleotides from mitochondria from human hepatoma and oat cell carcinoma while efflux from astrocytoma mitochondria is less. This efflux does not require exchangeable anions, i.e., adenine nucleotides or pyrophosphate, in the extramitochondrial medium, and is not sensitive to atractyloside. The efflux is more extensive with dinitrophenol and CCCP than with valinomycin-K+, and may account for the differential effects of the two types of uncouplers on uncoupler-stimulated ATPase of tumor mitochondria previously reported by us. Dinitrophenol and CCCP do not elicit any efflux of adenine nucleotides from normal liver mitochondria. Efflux of orthophosphate from tumor mitochondria is also greater with dinitrophenol and CCCP; however, the more interesting finding is that the concentration of orthophosphate in these mitochondria is unusually high, i.e., 10-40-times greater than the intramitochondrial phosphate concentration of liver mitochondria. Atractyloside sensitive transport of ATP and ADP in human tumor mitochondria has also been determined. Vmax values for both ADP and ATP transport are lower than those obtained with liver mitochondria, especially with ADP transport. ATP transport in tumor mitochondria is not affected by CCCP in contrast to the 4-5-fold stimulation observed in liver mitochondria.
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PMID:Characteristics of adenine nucleotide fluxes and transport in human tumor mitochondria. 632 Aug 71

The effects of oleficin, a polyene antibiotic of the nonmacrolide type, on isolated rat liver mitochondria were studied. Oleficin at a concentration of about 10 nmoles/mg protein increases both the rate of state 4 respiration and the "basal" ATPase activity of mitochondria. In contrast to this it inhibits the rate of both state 3 and uncoupled respiration and the DNP-stimulated ATPase activity. These inhibitions can be prevented by low concentrations (2 approximately 5 mM) of magnesium ions. Oleficin induces a high amplitude swelling of non-respiring mitochondria in the isoosmotic nitrate and chloride solutions of K+, Na+, Tris+, Tea+ or Mg2+. In contrast to that it does not induce swelling of mitochondria treated with ruthenium red in isoosmotic calcium acetate. Indirect evidence suggests that oleficin increases also the proton permeability of the inner membrane. The swelling observed in the isoosmotic solutions of monovalent cations can be prevented by low concentration (2 approximately 5 mM) of Mg2+. In the presence of the antibiotic Mg2+ and Ca2+ but not K+ and Na+, are transferred from an aqueous phase into a butanol-toluene bulk phase. Oleficin depletes Mg2+ and Ca2+ from mitochondria in a concentration dependent manner. Complete depletion of Mg2+ occurs only in the presence of EDTA, while that of Ca2+ does not need the chelator. It is concluded that the effects of oleficin on mitochondrial functions can be explained on the basis of an increase of the inner membrane permeability as the consequence of the depletion of Mg2+ from mitochondria caused by the antibiotic.
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PMID:Interaction of oleficin with the inner membrane of rat liver mitochondria. 644 31

Total content of unesterified fatty acids and activity of ATPases/latent, stimulated by Mg2+, 2,4-DNP, Mg2+ and 2,4-DNP/were studied in heart and liver mitochondria of rabbits with decompensated mitral valvular disease. The activities of Mg2+, DNP-, Mg2+ and DNP-stimulated ATPases were decreased in heart mitochondria. At the same time, content of unesterified fatty acids was increased. Content of the fatty acids was decreased in liver mitochondria and activity of ATPase was unaltered. Possible mechanisms of the alterations observed are discussed.
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PMID:[Changes in ATPase activity and nonesterified fatty acid concentration in heart and liver mitochondria in experimental mitral valve insufficiency]. 645 Apr 84

1. Dinitrophenol and maleate anions increase VATP on the 'washed', isolated, mitochondrial ATPase. Hydrolyses of iso-GTP and 2'-deoxy ATP are also stimulated, while hydrolyses of other nucleoside triphosphates (ITP, GTP etc.) are not. 2. Preincubation with ATP, iso-GTP or 2'-deoxy ATP results in a metastable enzyme form with a raised V and a reduced Km. Dinitrophenol stimulates both ATP and ITP hydrolyses by this form. 3. The Arrhenius plot of ATP (but not ITP) hydrolysis by the isolated ATPase shows a break at about 18 degrees C, apparently because the rate limiting step of hydrolysis changes as the temperature rises. 4. Adenylyl beta, gamma-imidodiphosphate (AdoPP[NH]P) inhibits ITP hydrolysis in a pseudofirst order reaction. Its binding is competitive with ITP. If the enzyme is preincubated with ATP, the rate of AdoPP[NH]P binding increases. It is concluded that AdoPP[NH]P inhibits by binding to the hydrolytic site of the enzyme. 5. We conclude that ATP hydrolysis is limited by diphosphate release and ITP hydrolysis by bond splitting. Energy release during ATP hydrolysis is maximal at the ATP binding step, and during ITP hydrolysis at bond splitting.
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PMID:Studies of the kinetics of the isolated mitochondrial ATPase using dinitrophenol as a probe. 645 12


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