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 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

Beef heart mitochondrial ATPase (F1) contained 2 mol of ADP and 1 mol of ATP/mol of enzyme, which resisted removal by Sephadex chromatography with dilute buffers or repeated precipitation with ammonium sulfate. The native enzyme also contained two apparently equivalent binding sites, which participated in readily reversible binding of adenyl-5'-ylimidodiphosphate (AMP-P(NH)P), with a Kd of 1.3 mum. The failure of AMP-P(NH)P to compete effectively with ADP for binding sites on F1 may be related to the failure of the analog to inhibit oxidative phosphorylation. Virtually complete removal of all adenine nucleotides from F1 occurred when the enzyme was chromatographed on columns of Sephadex equilibrated with 50% glycerol. No loss in ATPase activity was observed following removal of nucleotides from the enzyme, which was then capable of binding more than 4 mol of ADP and almost 5 mol of AMP-P(NH)P/mol of protein. Subsequent chromatography on columns of Sephadex equilibrated with dilute buffers containing Mg2+ removed only 1.5 mol of ADP and no AMP-P(NH)P from the enzyme. Reconstitution of F1 with ADP or with almost 5 mol of AMP-P(NH)P resulted in preparations that exhibited an undiminished capacity to restore oxidative phosphorylation in F1-deficient submitochondrial particles.
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PMID:Interaction of adenine nucleotides with multiple binding sites on beef heart mitochondrial adenosine triphosphatase. 12 56

Evidence is presented that mitochondrial ATPase has two types of sites that bind adenine nucleotides. The catalytic site, C, binds the substrates ATP, GTP, or ITP and the inhibitor guanylyl imidodiphosphate (GMP-PNP). A second type of site, R, binds ATP, ADP, adenylyl imidodiphosphate (AMP-PNP), and the chromium complexes of ATP or ADP. All of these substances binding to the R site inhibit the hydrolysis of ATP in a competitive manner; their inhibition of hydrolysis of ITP and GTP is noncompetitive. GMP-PNP inhibits oxidative phosphorylation in submitochondrial particles but AMP-PNP does not. The localization on mitochondrial membranes of sites for the binding of various antibiotics that inhibit oxidative phosphorylation is discussed.
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PMID:Exploring sites on mitochondrial ATPase for catalysis, regulation, and inhibition. 12 84

Mitochondrial ATPase from rat liver mitochondria contains multiple nucleotide binding sites. At low concentrations ADP binds with high affinity (1 mole/mole ATPase, KD = 1-2 muM). At high concentrations, ADP inhibits ATP hydrolysis presumably by competing with ATP for the active site (KI = 240-300 muM). As isolated, mitochondrial ATPase contains between 0.6 and 2.5 moles ATP/mole ATPase. This "tightly bound" ATP can be removed by repeated precipitations with ammonium sulfate without altering hydrolytic activity of the enzyme. However, the ATP-depleted enzyme must be redissolved in high concentrations of phosphate to retain activity. AMP-PNP (adenylyl imidodiphosphate) replaces tightly bound ATP removed from the enzyme and inhibits ATP hydrolysis. AMP-PNP has little effect on high affinity binding of ADP. Kinetics studies of ATP hydrolysis reveal hyperbolic velocity vs. ATP plots, provided assays are done in bicarbonate buffer or buffers containing high concentrations of phosphate. Taken together, these studies indicate that sites on the enzyme not directly associated with ATP hydrolysis bind ATP or ADP, and that in the absence of bound nucleotide, Pi can maintain the active form of the enzyme.
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PMID:Interaction of homogeneous mitochondrial ATPase from rat liver with adenine nucleotides and inorganic phosphate. 12 85

The tightly bound nucleotides of the beff-heart mitochondrial ATPase are released during cold inactivation followed by ammonium sulfate precipitation. During incubation at 0 degrees C the sedimentation coefficient (S20W) of the ATPase first declines from 12.1S to 9S. Prolonged incubation or precipitation with ammonium sulfate leads to dissociation of the 9S component into subunits with S20W of 3.5S. The 9S component still bears bound nucleotides which exchange more extensively and rapidly with added nucleotides than those bound to the active 12.1S component. The bound nucleotides are lost when the 9S form dissociates into the smaller subunits. Thus, firm binding of nucleotides is a property of the quarternary structure of the enzyme. The exchangeability of the nucleotides bound to the ATPase of chloroplast membranes is greatly increased in membranes illuminated in the presence of pyocyanine. Pi can exchange into both the beta and gamma positions of the bound nucleotides when the membranes are energized in the presence of Mg2+. The exchange of the nucleotides and the incorporation of Pi are insensitive to the inhibitor Dio-9 but are inhibited by the uncoupler S13. This inhibition by S13 parallels that of the inhibition of photosynthetic phosphorylation. These findings are discussed with regard to our hypothesis that electron transfer causes release of preformed tightly bound ATP from the ATPase by inducing a conformational change.
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PMID:The possible role of tightly bound adenine nucleotides in oxidative and photosynthetic phosphorylation. 12 89

Tightly bound adenine nucleotides are removed from multiple binding sites on beef heart mitochondrial ATPase (F1) by chromatography on columns of Sephadex equilibrated with 50% glycerol. Release of nucleotides from the enzyme is associated with large decreases in sedimentation velocity (from 11.9 S to 8.4 S) which may be observed in concentrated solutions of polyols. Polyol-induced conformational changes are reversed when the enzyme is returned to dilute buffers. The nucleotide-depleted enzyme restores oxidative phosphorylation in F1-deficient submitochondrial particles. Reconstitution of nucleotide-depleted F1 with the ATP analog (adenylyl-imidodiphosphate (AMP-PNP), almost 5 moles of AMP-PNP per mole of enzyme, results in preparations with substantially inhibited ATPase activity which nevertheless restores oxidative phosphorylation and the 32Pi-ATP exchange reaction in F1-deficient submitochondrial particles. Incubation of the analog-labeled enzyme with ATP and Mg++ results in partial displacement of the analog and a time-dependent recovery of ATPase activity.
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PMID:Physical and enzymatic properties of nucleotide-depleted beef heart mitochondrial adenosine triphosphatase. 12 61

Effect of respiration toxins is studied on some properties of mitochondrial membranes and functions connected with ion transport for the expence of ATP energy. The combination of three respiration inhibitors (cyanide, antimycin and rotenone) was shown to develope the following effects: 1) the inhibition of K+ accumulation by mitochondria at the presence of ATP and valinomycin; 2) the decrease in acidification of non-mitochondrial space, accompanying to the K+ transport; 3) the activation of latent mitochondrial ATPase; 4) the inhibition of DNP-stimulated ATPase; 5) the inhibition of mitochondria swelling, caused by K+, Ca2+, or dimethyldibenzylammonium (DDA+) at the presence of ATP+phopshate (or acetate); 6) the stimulation of passive mitochondria swelling in 0.1 MNH4NO3; 7) the inhibition of ATP-induced contraction of mitochondria, swelling in NH4NO3. The data obtained are discussed in a wiev of the conception, which suggests that the attaching of inhibitors to respiration enzymes changes the configuration of the latters, thus disturbing natural structural bond of these enzymes with other protein components of the membrane. The latter can result in the impair of electroisolating membrane properties, in the increase of its conductivity for H+ and other ions, and in the decrease of Vm values of some enzymatic reaction, which are not directly connected with the respiration chain (such as ATPase reaction).
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PMID:[Respiration toxins as inhibitors of ion transport, supported by ATP hydrolysis, in mitochondria]. 12 71

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

Several classes of anti-inflammatory agents including acetyl-salicylic acid, salicylic acid, flufenamic acid, phenyl-butazone, indometacin, oxyphenyl-butazone, and mefenamic acid were found to be inhibitors of rat liver mitochondrial ATPase in both intact and freeze-ruptured mitochondria. The freeze-ruptured mitochondrial ATPase was found to be Mg2+- and ATP-concentration dependent. The standard uncoupler, 2,4-dinitrophenol, not possessing anti-inflammatory activity, activates the enzyme in both preparations. A number of compounds of various structural classes possessing no anti-inflammatory property in vivo were found to have no inhibitory effect on the enzyme. This inhibition of ATPase by anti-inflammatory agents could be used as an in vitro test method for the primary screening of potential anti-inflammatory agents.
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PMID:Influence of anti-inflammatory agents on rat liver mitochondrial ATPase. 13 89

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


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