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)

2,4-Dinitrophenol (DNP) was found to cause a "clearing response" of myosin B in a medium in which "superprecipitation" of myosin B would otherwise take place. The effect of actin concentration on Mg-ATPase [EC 3.6.1.3] of HMM was studied in the presence and absence of DNP. The results indicate that DNP causes an increase rather than a decrease in the affinity of HMM for actin, and that it causes a decrease only in the actin-activated portion of the Mg-ATPase activity. Using a light-scattering technique, it was shown that neither the ATP-induced dissociation of acto-HMM nor subsequent reassociation is significantly affected by the presence of DNP. As for the formation of the myosin-phosphate-ADP complex in the myosin-ATPase reaction, it was shown that formation of the reactive complex is not affected by DNP. It can thus be concluded that DNP inhibits the decomposition of the actomyosin-phosphate-ADP complex, which is thought to be coupled with superprecipitation.
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PMID:2,4-Dinitrophenol as a specific inhibitor of the breakdown of the actomyosin-phosphate-ADP complex. 13 36

The purification of a substance which protects mitochondrial activity against its decay in association with various cerebral pathologies, and the effect of this substance in vitro and in vivo have been mentioned. Defatted egg albumin was hydrolyzed with pronase, and diafiltrated through mesh, to obtain fractions of molecular weight less than 5,000. The diafiltrate was further fractionated using Sephadex G-25 column chromatography, and a fraction which had a protective action against the decay of mitochondrial DNP-ATPase activity was gathered. This digested egg albumin (DEA 5,000 S) showed no immunological reaction and seemingly penetrated well through the cell membrane. DEA 5,000 S prevented the decay of DNP-ATPase activity and swelling of brain mitochondria during aging in vitro. Also, the administration of DEA 5,000 S in vivo shortened the duration of unconsciousness and reduced EEG abnormalities in rats subjected to hypoxia in a special chamber filled with N2 gas. It is suggested that this Digested Egg Albumin has a marked action in restoring the function of metabolically impaired brain.
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PMID:The pharmacological action of pronase-digested egg albumin upon cerebral hypoxia. 14 70

The effects of the ionophore lysocellin on the movements of Ca2+, Mg2+ and alkali metal cations and its effect on energy utilization by rat liver mitochondria have been investigated. At a concentration of 0.05 micrometer, lysocellin induced dissociation of membrane-bound calcium, and an apparent steady state was established across the inner membrane between energy-linked calcium accumulation and the ionophore-induced depletion of calcium. No detectable efflux of intramitochondrial Ca2+ and Mg2+ was induced by 0.05 micrometer lysocellin, but the uptake of exogenously added calcium was significantly inhibited. The ionophore augmented Mg2+ release from mitochondria induced by Ca2+ addition and also caused rapid release of K+ from mitochondria preloaded with K+ by valinomycin or monazomycin. High levels (0.5 approximately 10 micrometer of lysocellin caused massive depletion of endogenous Ca2+, Mg2+ and K+ from mitochondria, resulting in disruption of mitochondrial functions including release of state 4 respiration, stimulation of ATPase and inhibition of ADP- or DNP-stimulated respiration. Structure-activity studies with chemically modified compounds of lysocellin indicated the important role of terminal carboxylic acid and C21 hydroxyl function in the activity of the ionophore, and there is a good correlation between the effect of lysocellin on mitochondrial cation movements and its ability to complex with cations determined in an organic solvent-water two-phase partition system.
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PMID:Studies on the ionophorous antibiotics. XII. Effects of ionophore lysocellin on cation distribution and respiration in mitochondria. 14 23

In Saccharomyces cerevisiae the uptake of cytosine, uracil and uridine is mediated by three permeases. Using mutants blocked in the metabolic utilization of these three compounds we were able to study their specific uptake. Cytosine and uridine show simple saturation kinetics, whereas uracil uptake is a biphasic process. A comparison of the effects of several inhibitors of energy metabolism on these uptake systems was made. Striking differences were found. 2,4-Dinitrophenol (10(-3) M) and NaN3 (10(-2) M) inhibit the entry of the three compounds to similar extent, but chlorhexidine (10(-5) M) and Dio 9 (50 microgram/ml) which are ATPase inhibitors in vitro strongly impaired cytosine and uridine entry and remained without effect on uracil uptake. We provisionally conclude that these systems may be energized by different mechanisms. In the case of cytosine and uridine permease, a membrane ATPase is possibly involved in the process of energetic coupling whereas this does not seem to be so for uracil.
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PMID:Properties of three distinct pyrimide transport systems in yeast. Evidence for distinct energy coupling. 15 49

The oxidative phosphorylation and ATPase activity (initial and stimulated by DNP and Mg2+) in tumor mitochondria were investigated. The intact mitochondria of Zajdela hepatoma, in contrast to liver mitochondria, exhibit the ATPase activity which is slightly stimulated by 2,4-dinitrophenol and is markedly activated by Mg2+. The mitochondria from transplantable solid tumors (adenocarcinoma 755, Iensen sarcoma, sarcoma 45) despite satisfactory morphological integrity under electron microscopy are biochemically less intact than the mitochondria of hepatoma. ATPase of these mitochondria is also slightly stimulated by 2,4-dinitrophenol and significantly by Mg2+. The ATPase activity of thymus mitochondria, the normal tissue with sufficiently high proliferative activity, corresponds to that of tumor mitochondria. The total amount of enzyme in mitochondria of tumors investigated and thymus is not lowered, since the ATPase activity in the presence of both DNP and Mg2+ corresponds to the ATPase activity of liver mitochondria. The Mg2+ ATPase activity of tumor mitochondria is not sensitive or is only partly sensitive to oligomycin. The data obtained are indicative of a high lability of the phosphorylating system in tumor and thymus mitochondria. A possibility of reorganization of the energy mechanism of tumor mitochondria and some normal tissues in connection with increased metabolism requiring high energy consumption, is discussed.
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PMID:[Some peculiarities of ATPase in tumor mitochondria]. 15 49

Linoleate hydropepoxide, purified by silica gel chromatography and at concentrations 70-100 nmol/mg mitochondrial protein, activated state 4 respiration and Mg-ATPase activity of mitochondria to levels of 80% and 25%, respectively, of those induced by 300 microM DNP, and completely inhibited oxidative phosphorylation. These effects are the same as those caused by linoleate, but the hydroperoxide caused more rapid degeneration of the activated respiration of mitochondria than linoleate. Further addition of the hydroperoxide induced oligomycin-insensitive Mg-ATPase to a level 3 times that obtained with DNP, accompanied by clearing of the mitochondrial suspension and release of malate dehydrogenase from the matrix. The extent of the effects caused by the methyl ester of linoleate hydroperoxide was much less than by the free acid.
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PMID:The effects of linoleate hydroperoxide on respiration and oxidative phosphorylation of rat liver mitochondria. 15 92

Ultrafiltered fur seal muscle hydrolysate was divided into eleven fractions by gel filtration on Sephadex G-15. One of the fractions (Fraction G9) accelerated the ATPase activity of carp myosin B to a rate about two-fold faster than that of the control. Fraction G9 showed a single ninhydrin spot in its silica gel thin layer chromatograph, and gave a positive test for tryptophan by the p-dimethylaminobenzaldehyde method, while tests for tyrosine, and for arginine were negative. The ion exchange amino acid analysis of its acid hydrolysate showed a predominant content of lysine, nearly equivalent to the amount of tryptophan determined from its UV absorbancy and the p-dimethylaminobenzaldehyde method. The N-terminal amino acid analysis gave di-DNP-Lys as the sole DNP-amino acid. The structure of the ATPase accelerating peptide fraction, Fraction G9, was deduced to be Lys-Trp.
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PMID:Nature of adenosine triphosphatase accelerating peptide from hydrolysate of fur seal muscle. 16 Sep 12

Changes in the adenine nucleotide metabolism after an oral glucose load were studied in the liver of normal and alloxan-diabetic rats. Changes in the energy charge were positively correlated with those in the blood glucose and plasma immunoreactive insulin levels. One hour after an oral glucose load when the plasma immunoreactive insulin levels increased maximally, the energy charge increased maximally from 0.846 to 0.867 (P less than 0.001). The increase in the energy charge was accompanied by a concomitant decrease in the ADP levels (P less than 0.05). The respiratory control ration, state 3 respiration per unit of cytochrome a (+a3), and DNP-induced ATPase activity per unit of cytochrome a (+a3) increased significantly. The adenylate kinase and pyruvate kinase activities in the liver remained unchanged. On the other hand, the energy charge in the liver of alloxan-diabetic rats did not increase significantly after an oral glucose load. It was suggested that an increase in the energy charge of the liver is attributable to the more rapid flux of intermediary metabolism in the enhanced ADP-phosphorylating reactions by mitochondria, owing to an elevated level of insulin available to the hepatic cells.
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PMID:Changes in adenylate energy charge of the liver after an oral glucose load. 17 25

Mitochondria were isolated from Euglena gracilis strain Z by pressure-breakage of the cells and sucrose-cushion centrifugation. Multiple peaks (2-4) were observed in the rate of phosphorylation with Mg-ADP-phosphate concentration curves. The phosphorylative and oxidative activities were highest with NADH as the substrate, moderate with succinate, and lowest with glutamate. Inhibition of phosphorylation with 2,4-dinitrophenol and carbonyl cyanide, m-chlorophenylhydrazone gave sigmoidal concentration curves, with the extent of inhibition by DNP depending on the substrate used. Inhibition of phosphorylation by valinomycin, atractyloside, or carboxyatractyloside was only approximately 60%. Oligomycin inhibited phosphorylation in 2 phases at low and high concentrations; it inhibited Mg-ATPase in a sigmoidal fashion. Both phosphorylation and oxidation had discontinuities in Arrhenius plots at 34 C and 18 C. The relative Mg2+-dependent nucleoside triphosphatase activity was: 1 for ATP and GTP, 0.6 for ITP, 0.15 for CTP and UTP; with Ca2+ in place pf Mg2+ this activity was 0.35. Both DNP and CCCP stimulated the Mg-ATPase 50-200%. The optimal pH for the stimulation was approximately 7 regardless of the uncoupler used, and approximately 8 without the uncouplers. The few differences observed between mitochodria from Euglena and those from other sources are probably due to the fragmentation of the reticular mitochondrial structure during isolation and not to unique characteristics of these mitochondria.
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PMID:Some biochemical properties of mitochondria isolated from Euglena gracilis. 19 37

Hydrolysis of extramitochondrial ATP by coupled Zajdela hepatoma mitochondria is not stimulated by uncouplers of oxidative phosphorylation. The results of the present study show that the hydrolysis of intramitochondrial ATP in these mitochondria is stimulated by DNP and CCCP. It is proposed that the uncoupler insensitivity of ATPase in coupled Zajdela hepatoma mitochondria with exogenous ATP as a substrate result from an altered functional relationship between ATPase and ADP, ATP translocase.
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PMID:Mitochondrial adenosine triphosphatase of Zajdela hepatoma. III. Effect of uncouplers on the hydrolysis of intramitochondrial ATP. 20 77


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