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:3.6.3.14 (ATP synthase)
7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of sodium salicylate (SS), phenazone (Ph) and aminophenazone (APh) on mitochondrial respiration respiration and oxidative phosphorylation were studied in vitro, SS inhibited state 3 but stimulated state 4 of respiration, if alpha-ketoglutarate and succinate were used as the substrates. The inhibition of state 3 of respiration was not reversed by 2,4-dinitrophenol (DNP). Ph and APh inhibited the respiratory state 3 without affecting the state 4 in the presence of the same substrates, and the produced inhibition in state 3 was reversible by DNP. Studies on ATP synthesis have revealed that SS was the only antypyretic tested that exerted an uncoupling action. SS stimulated the mitochondrial ATPase activity but inhibited it after uncoupling of oxidative phosphorylation with DNP. The mitochondrial ATPase activity remained uninfluenced by Ph or APh. The only similar action of all the drugs investigated was the inhibition of oxidation in the respiratory state 3.
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PMID:The effects of antipyretics on metabolism processes in rat liver mitochondria. Part I. The action of sodium salicylate, and pyrazolones on the reaction of respiratory chain. 0 75

The immediate and direct regulation of insulin release by circulating nutrients, especially glucose, is thought to be mediated in the pancreatic B-cell by a sequence of metabolic, ionic, and motile events. On the basis of previous work, it is assumed that the process by which glucose is recognized as an insulinotropic agent entirely depends on the metabolic changes evoked by the sugar in the islet cells. Several factors are considered as possible candidates for the coupling between these metabolic changes and subsequent ionic events such as altered phosphate, chloride, sodium, potassium, and calcium handling. It is acknowledged that changes in the concentrations of glycolytic intermediates and cyclic nucleotides (adenosine- or guanosine-3', 5'-cyclic monophosphate), or both, could play a modulatory role upon stimulated insulin release. However, the initiation of insulin release seems to depend on the generation of two essential coupling factors: H+ and reduced pyridine nucleotides. The changes in H+ fluxes may account for the glucose-induced decrease in K+ and Ca2+ fractional outflow rate, all three parameters displaying hyperbolic-like dose-response curves with half-maximal values at noninsulinotropic glucose concentrations. The changes in NAD(P)H concentration may account for a glucose-induced Ca2+--Ca2+ exchange process due to a change in affinity of a native ionophoretic system. The dose-response curves for these parameters yield a sigmoidal pattern analogous to that which depicts the rate of insulin release at increasing glucose concentrations. It is proposed that such a coupling between metabolic and cationic events is operative in response to other insulinotropic nutrients and that its time course may be relevant to the phasic aspect of insulin release. Thus, the nutrient-induced release of insulin (and possibly other pancreatic hormones), which is essential for the regulation of fuel homeostasis, would depend on the capacity of circulating nutrients to act as a fuel in the islet cells. This concept raises a question as to the existence and nature of feedback mechanisms regulating the metabolic fluxes in the islet cells as a function of their energy expenditure.
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PMID:Insulin release: the fuel hypothesis. 3 43

The soluble beef heart mitochondrial ATPase (F1) contains eight sulfhydryl groups and two disulfide bonds. N-Ethylmaleimide has been used to radioactively label the sulfhydryl groups before and after cleavage of the disulfide bonds by dithiothreitol. After subjecting the labeled protein to polyacrylamide gel electrophoresis in sodium dodecyl sulfate and measuring radioactivity in each of the separated subunits the location of all the sulfhydryl groups and the disulfide bonds may be specified. The conclusions are supported by direct examination of depolymerized, unreduced, enzyme by polyacrylamide gel electrophoresis. The results also indicate that current ideas regarding the overall subunit structure of this enzyme may be incorrect, and this is discussed in light of new data presented here.
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PMID:Mitochondrial adenosine triphosphatase. Location of sulfhydryl groups and disulfide bonds in soluble enzyme from beef heart. 12 57

The lipid-free particulate preparations of the mitochondrial ATPase require phospholipid for activity and can be inhibited by oligomycin, as has been demonstrated previously. In this communication a steady state analysis of the activation of a particulate preparation of the ATPase by phospholipids and its subsequent inhibition by oligomycin has been carried out. The relative affinity of the ATPase for purified phospholipids has been determined by measuring the Km for activation (Ka) for several phospholipids. The Ka values varied from 30 to 100 mum. The Vmax in the presence of phosphatides varies from 0.29 to 1.11 mumol ATP hydrolyzed/min/mg of protein; no correlation is noted between the relative affinity of the enzyme for a phospholipid and the V max value. Higher V max values are noted with the more acidic phospholipids, however. Sodium dodecyl sulfate and monoolein also activate with Ka values of 25 and 800 mum, respectively. Diglycerides, however, do not activate. With all lipids the ATPase activity stimulated is oligomycin-sensitive. The Ki values for oligomycin range from 0.1 to 0.6 mum. Oligomycin is a competitive inhibitor with respect to all the phospholipids tested except phosphatidylethanolamine and phosphatidyglycerol. It is also competitive with respect to sodium dodecyl sulfate (k-i equals 0.94 mum). In reciprocal plots of activity versus ATP concentration, with and without oligomycin, an intercept consistent with either mixed or partial noncompetitive inhibition kinetics is noted. Comparable K-i values for oligomycin are obtained when calculated assuming either mixed or partial noncompetitive inhibition. The Km for ATP is the same in the unactivated and the lipid activated particulate ATPase; the value obtained is slightly lower than the Km for ATP in the solubilized, purified ATPase. Using a spectrophotometric assay the time required for activation with phospholipid and inhibition with oligomycin has also been determined. This investigation suggests the possibility that activation of the ATPase is due a position to interact with the water-soluble substrate. Consistent with the above suggestion is the supposition that the lipids do not necessarily confer inhibitor sensitivity to the ATPase, but rather allow an oligomycin-sensitive activity to be expressed.
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PMID:The relationship between the bovine heart mitochondrial adenosine triphosphatase, lipophilic compounds, and oligomycin. 12 47

The membrane-bound coupling factor from Mycobacterium phlei was solubilized from membrane vesicles by washing with low ionic strength buffer or 0.25 M sucrose. The solubilized enzyme exhibited coupling factor, latent ATPase, and succinate oxidation-stimulating activity. Purification by affinity chromatography using Sepharose coupled to ADP yielded a homogeneous preparation of latent ATPase which was purified about 200-fold with an 84% yield in a single step. Purified latent ATPase exhibited coupling factor activity but no succinate oxidation-stimulating activity. The molecular weight of latent ATPase was determined to be 250,000 +/- 10,000 by Sephadex G-200 chromatography. The ATPase was unmasked by trypsin treatment and activated by Mg2+ ion. However, trypsin treatment inactivated the coupling factor activity in the purified enzyme, indicating that the catalytic sites for ATPase and coupling activity are different. Unlike mitochondrial ATPase, latent ATPase from M. phlei was not cold-labile. Of the nucleoside triphosphates, UTP, ITP, and epsilon-ATP (1-N6-ethenoadenosine triphosphate) were hydrolyzed to a lesser extent compared to ATP. Kinetic data showed that ADP acted as a competitive inhibitor of latent ATPase activity with a Ki of 5 x 10(-3) M. Uncouplers of oxidative phosphorylation and respiratory inhibitors did not affect the latent ATPase activity, while sodium azide (0.1 mM) inhibited the latent ATPase activity.
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PMID:Energy-transducing membrane-bound coupling factor-ATPase from Mycobacterium phlei. I. Purification, homogeneity, and properties. 12 54

A bean chloroplast coupling factor (CF1) with latent Ca2+-dependent ATPase activity was studied. Immunodiffusion of bean (Phaseolus vulgaris) chloroplast and etioplast coupling factors and spinach coupling factor against antiserum to spinach coupling factor showed partial identity of the bean coupling factor with that of spinach. An immunoelectrophoretic comparison, under dissociating conditions, of bean leaf extracts and spinach extracts containing CF1 subunits (as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis) gave identical results for both extracts. At least six distinct polypeptide species were found. The major species had molecular weights of 42 000, 59 000 and 63 000 daltons. Amino acid analysis of electrophoretically purified bean CF1 gave results similar to those published for spinach CF1.
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PMID:Subunit studies of coupling factor 1 of bean chloroplasts. 13 66

Preparation of surface membranes from mouse L-cells using a technique previously described in the literature [Perdue & Sneider, 1970] allowed characterization of a Ca-activated ATPase apparently separate from the mitochondrial ATPase also dependent on calcium. This enzyme is associated with the Na-K-ATPase, a marker for surface membranes, and not wilth alkaline phosphatase, a mitochondrial enzyme. In temperature sensitivity, pH dependence and inhibition by ethacrynic acid, the partially purified enzyme has properties similar to those previously described for active calcium efflux from these cells. For maximal activity of the enzyme system magnesium and sodium are required, although the calcium transport from whole cells was apparently independent of both. Adenosine triphosphate only was metabolized by the enzyme system, whereas CTP could be utilized for calcium transport from 'ghost' cells, probably as a result of intracellular conversion to ATP. It is suggested that the active calcium transport from cultured L-cells is closely linked to the calcium dependent ATPase, and that the method of calcium extrusion is similar to that described for red blood cells.
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PMID:Properties of the calcium-activated adenosine tri-phosphatase from L-cell membranes. 13 77

A preparation of soluble mitochondrial ATPase (coupling factor F1) containing no gamma and delta minor subunits has been isolated. The minor-subunits-deficient F1 was found to be competent in ATP hydrolysis. However, it did not demonstrate a "coupling" effect in EDTA-submitochondrial particles. A portion of the ATPase activity of EDTA particles, stimulated by the minor-subunits-deficient F1, was insensitive to oligomycin. ATPase activity of Na+-particles was changed only slightly by this F1. It is suggested that gamma and delta subunits are necessary to form specific contacts between the F1 molecule and components of the mitochrondrial membrane.
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PMID:Functional role of soluble mitochondrial ATPase subunits. 13 32

1. The following bifunctional reagents, dimethylsuberimidiate, dimethyladipimidate, methylmercaptobutyrimidate have been used to produce dimers between the neighboring subunits of beef heart F1-ATPase. 2. Treatment of beef heart F1-ATPase with dimethylsuberimidate or dimethyladipimidate resulted in the formation of four cross-linked products. Their molecular weights determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were 11 500, 105 000, 95 000 and 80 000, respectively. The products of molecular weight 115 000 and 105 000 were predominant and could be detected at the early stage of the cross-linking reaction. Treatment of beef heart F1-ATPase with methylmercaptobutyrimidate resulted in the accumulation of the product of molecular weight 115 000 and in traces of products of lower molecular weight. When the cross-linked products obtained with methylmercaptobutyrimidate were cleaved by beta-mercaptoethanol, the original gel electrophoresis pattern was restored. 3. Cross-linking of beef heart F1-ATPase by dimethylsuberimidate, dimethyladipimidate and methylmercaptobutyrimidate was accompanied by a loss of the ATPase activity. Cleavage of the cross-linked products obtained with methylmercaptobutyrimidate did not restore the original ATPase activity. 4. Identification of subunits A and B in the products of molecular weight 115 000 and 105 000 was achieved by specific labeling of subunit A with N-[14C]ethylmaleimide and of subunit B by chloronitro [14C]benzooxodiazole. Both products were able to bind N-[14C]ethylmaleimide; only the 105 000 dalton product was able to bind chloronitro [14C]benzooxodiazole. 5. The product of molecular weight 115 000 obtained by treatment of beef heart ATPase with methylmercaptobutyrimidate could bind N-[14C]ethylmaleimide. Its cleavage, following N-[14C]ethylmaleimide binding, yielded one labeled peptide identified with subunit A by polyacrylamide gel electrophoresis. 6. The above results indicate that the product of molecular weight 115 000 is a dimer containing two subunits A and that the product of molecular weight 105 000 is a dimer containing one subunit A and one subunit B. It can therefore be concluded that, in beef heart F1-ATPase, the A subunits are close to each other and that subunit A is close to subunit B. In contrast the B sublnits are probably too far from each other to be cross-linked by dimethylsuberimidate, dimethyladipimidate or methylmercaptobutyrimidate.
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PMID:Structure of beef heart mitochondrial F1-ATPase. Arrangement of subunits as disclosed by cross-linking reagents and selective labeling by radioactive ligands. 13 87

1. Stimulation of the Escherichia coli ATPase activity by urea and trypsin shows that the ATPase activity both in the membrane-bound and the solubilized form is partly masked. 2. A protein, inhibiting the ATPase activity of Escherichia coli, can be isolated by sodium dodecyl sulphate polyacrylamide gel electrophoresis of purified ATPase. The inhibitor was identified with the smallest of the subunits of E. coli ATPase. 3. The molecular weight of the ATPase inhibitor is about 10,000, as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis and deduced from the amino acid composition. 4. The inhibitory action is independent of pH, ionic strength or the presence of Mg2+ or ATP. 5. The ATPase inhibitor is heat-stable, insensitive to urea but very sensitive to trypsin degradation. 6. The Escherichia coli ATPase inhibitor does not inhibit the mitochondrial or the chloroplast ATPase.
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PMID:Isolation and characterization of an inhibitory subunit of the Mg2+--Ca2+-ATPase of Escherichia coli. 13 64


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