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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 ATPase (EC 3.6.1.3) of Bacillus subtilis can be solubilized by a shock-wash process. Two procedures for purifying the solubilized enzyme are reported. A protease inhibitor, phenylmethane sulfonylfluoride, was introduced in the solubilization and purification step. The resultant ATPase purified by density gradient centrifugation has a molecular weight of 315 000, an s20,w of 13,4 and an amino acid composition very similar to bacterial ATPases already studied. After exposure to polyacrylamide gel electrophoresis in presence of sodium dodecyl sulphate (SDS), or 8 M urea or SDS-urea, the purified ATPase can be dissociated in two non-identical subunits of molecular weights 59 000 (alpha) and 57 000 (beta) with different charges. Kinetic studies showed that Ca2+ or Zn2+ are required for ATPase activity, although Mg2+ was uneffective. At optimal Ca2+ concentration, the Mg2+ has an inhibitory effect. The Km for ATP is 1.3 mM. Inhibitors of the oxydative phosphorylation, of the mitochondrial ATPase and of the (Na+ + K+)-ATPase are studied.
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PMID:Membrane ATPase of Bacillus subtilis. I. Purification and properties. 14 10

The F1 portion of H(+)-translocating ATPase as purified from membrane vesicles of Vibrio parahaemolyticus by a rapid procedure. The whole purification process (from culture of cells to purification of the enzyme) could be completed in 1 day. The F1-ATPase consists of five subunits (alpha, beta, gamma, delta and epsilon) like F1 of Escherichia coli and other microorganisms. The F1-ATPase of V. parahaemolyticus showed some interesting properties. Its activity was greatly stimulated by high concentrations (about 0.5 M) of SO4(2-), SO3(2-) and CH3COO-, their effects decreasing in this order. Among the anions tested, Cl- and NO3- were ineffective, or rather inhibitory, and cations had no significant effects. Ethanol (or methanol) stimulated the activity 2- to 3-fold. The activity was inhibited by 4-acetamido-4'-isothiocyanostilbene 2,2'-disulfonate (SITS) (an anion exchanger inhibitor), tetrachlorosalicylanilide (TCS) (an H+ conductor), azide and N-ethylmaleimide. Zinc inhibited the activity only slightly, although it strongly inhibited the ATPase activity in membrane vesicles.
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PMID:Rapid purification and characterization of F1-ATPase of Vibrio parahaemolyticus. 214 93

Divalent cations are divided into two groups in relation to their ability to promote ATP synthase catalyzed reactions. In the presence of Mg2+, the following pattern rules: (i) uncoupler-stimulated ATP hydrolysis of Rhodospirillum rubrum chromatophores which shows an optimum concentration of the divalent cation; (ii) ATP-induced proton pumping in chromatophores; (iii) light-induced ATP synthesis in chromatophores; (iv) no or very low ATPase activity of purified F1-ATPase unmasked by diethylstilbestrol or n-octyl beta-D-glucopyranoside. In the presence of Ca2+, the following pattern occurs: (i) no stimulation of the ATP hydrolysis in chromatophores by carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone; (ii) no ATP-induced proton pumping; (iii) no light-induced ATP synthesis; (iv) a high ATPase activity of the purified F1-ATPase which is inhibited by diethylstilbestrol and n-octyl beta-D-glucopyranoside. Co2+, Mn2+, and Zn2+ are members of the "Mg2+-group", whereas Cd2+ is suggested to fall between the two groups. Intrinsic uncoupling of the membrane-bound ATP synthase has been suggested to account for the effect caused by Ca2+ in chloroplasts [Pick, U., & Weiss, M. (1988) Eur. J. Biochem. 173, 623-628]. Such an interpretation is consistent with our results on chromatophores. The uncoupling cannot occur at the level of the membrane since neither light-induced nor Mg-ATP-induced proton pumping is affected by Ca2+. A conformational change is suggested to be the reason for this intrinsic uncoupling, and it is proposed to be controlled by the diameters of the divalent cations (Ca2+ greater than Cd2+ greater than Mn2+ greater than Co2+ greater than Zn2+ greater than Mg2+).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Division of divalent cations into two groups in relation to their effect on the coupling of the F0F1-ATPase of Rhodospirillum rubrum to the protonmotive force. 248 79

Atomic absorption and electron paramagnetic resonance spectroscopy were used to study the metal binding sites of beef heart mitochondrial ATPase (F1). Quantitative and qualitative properties of these sites are described. Two different separation techniques were able to distinguish two very tight sites from one tight (easily exchangeable) metal binding site on F1. Of these sites, two are specific for magnesium while one can be substituted with Mn2+, Co2+, or Zn2+. When MgAMP-PNP was incubated with F1, a fourth metal was bound to the enzyme. The carboxyl group modified by dicyclohexylcarbodiimide is shown not to be involved in binding of any of the tightly bound metals. Qualitative properties of the metal binding sites using the Mn2+-enzyme complex as a probe were ascertained using EPR at pH 6.8 and 8.0. CrATP and Mn2+ appear to bind to different metal sites on F1. The possible role of the metals in regulation of catalysis, and their relation to nucleotide binding is discussed.
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PMID:Metal interactions with beef heart mitochondrial ATPase. 286 Jan 5

The oxidants of the SH groups (o-iodozobenzoate, oxidized glutathione, etc.) and the divalent cations of some metals (Zn2+ and Cd2+) significantly slow down the rate of inactivation by the protein inhibitor of the isolated F1-ATPase and ATPase in submitochondrial particles. Modification of SH groups in the ATPase does not change the rate of inactivation but completely prevents the effect of oxidants.
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PMID:The oxidation of sulfhydryl groups in mitochondrial F1-ATPase decreases the rate of its inactivation by the natural protein inhibitor. 286 62

Purified F1-ATPase from Micrococcus lysodeikticus contains zinc in the amount of 1 mol/mol of enzyme. This zinc content correlates with standard values of ATPase activity (assayed with Ca2+-ATP as substrate) of the protein, i.e. 5--6 mumol substrate hydrolysed . min-1 . mg-1. Prolonged dialysis against EDTA results in a zinc-free protein which concomitantly loses its ATPase activity. Chelators such as Zincon, EDTA and L-cysteine inhibit the ATPase activity in concentration and/or time dependence related to their affinity for the metal ion involved. Reconstitution of the metallo (Zn2+) protein is demonstrated by the incorporation to the zinc-free protein of 65Zn2+ in amount near the 1 mol/mol of enzyme. This incorporation was concomitant with the regain of ATPase activity. The inhibition by EDTA and Zincon is reversed specifically by Zn2+ while the inhibition by EDTA is prevented by Zn2+ and Mn2+ and to, a minor extent, by Cd2+. Zn2+ and Ca2+ ions are involved and are probably mandatory in the ATPase activity of M. lysodeikticus F1 but their roles appear to be different and not exchangeable. Other divalent metal ions inhibit the Ca2+-ATPase activity of the Zn2+ protein by the following decreasing order; Hg2+, Fe2+, Co2+, Cd2+, Mn2+, Mg2+. M. lysodeikticus F1-ATPase is thus identified as a metallo (zinc) protein, which requires additional divalent metal ions for ATP hydrolysis.
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PMID:Identification of a bacterial energy-transducing ATPase as a metallo (Zn2+) protein. Effect of chelating agents and divalent metal ions on ATPase activity. 621 May 27

The effects of anions on the ATPase activity of submitochondrial particles from mouse liver cells were investigated. Thiocyanite decreased the ATP hydrolysis, acting as a competitive inhibitor with respect to sulfite. All the anions tested changed the ATPase activity noncompetitively towards Mg-ATP. The hydrolysis of CTP, GTP, ITP and UTP was insensitive to sulfite and thiocyanate. In the presence of Mn2+, Ca2+, Co2+, Zn2+ and Ba2+ an anion-dependent hydrolysis of ATP took place. It was assumed that the anions control the rate of the limiting step of the ATPase reaction, since sulfite and thiocyanate change the activation energy of ATP hydrolysis. The data obtained are discussed in terms of a previously proposed mechanism of the anions effect on the activity of mitochondrial ATPase.
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PMID:[Effect of anions on the ATPase activity of submitochondrial particles]. 621 16

The soluble F1-ATPase from the thermophilic bacterium PS3 (TF1) contains no endogenous adenine nucleotides and contains about 0.2 g ions of Mg2+/mol which resists removal by repeated centrifugation-elution on columns of Sephadex G-50. The isolated enzyme will not bind additional Mg2+ added in the absence of adenine nucleotides nor is the rate of inactivation of the isolated enzyme by dicyclohexylcarbodiimide (DCCD) affected by the addition of Mg2+. When ADP is added to isolated TF1, a 1:1 TF1 X ADP complex is formed which is stable to repeated gel permeation on columns of Sephadex G-50 subjected to centrifugation-elution. On formation of the 1:1 TF1 X ADP complex, the rate of inactivation of the enzyme by DCCD is accelerated 6-fold. The rate of inactivation of the 1:1 TF1 X ADP complex by DCCD is not further stimulated in the presence of 2 mM ADP which indicates that the binding of ADP to a single site in the enzyme is sufficient to promote maximal stimulation of the inactivation. Addition of Mg2+ to the 1:1 TF1 X ADP complex results in the binding of about 1 g ion of Mg2+/mol of enzyme. The 1:1:1 TF1 X ADP X Mg2+ complex thus formed is sluggishly inactivated by DCCD. When the Mg2+ is removed from the TF1 X ADP X Mg2+ complex by treatment with trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, the rate of inactivation of the enzyme by DCCD is accelerated 4-fold. Other divalent metal ions protect the 1:1 TF1 X ADP complex against inactivation by DCCD. Of these, Mn2+, Zn2+, Co2+, and Cd2+, which are about as equally effective as Mg2+ as cofactors for the hydrolytic reaction when present at 0.2 mM, offer about equal protection of the complex against inactivation by DCCD also when present at 0.2 mM. These results indicate that the binding site for ADP in the 1:1 TF1 X ADP complex is a catalytic site. TF1, inactivated by 92% with DCCD, has the same capacity to bind ADP as the active enzyme, forming a tight 1:1 TF1 X ADP complex which is stable to repeated centrifugation-elution on columns of Sephadex G-50. The 1:1 TF1 X ADP complex retains its capacity to bind Mg2+ to form the 1:1:1 TF1 X ADP X Mg2+ complex after it is inactivated by 88% with DCCD.
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PMID:Modulation by ADP and Mg2+ of the inactivation of the F1-ATPase from the thermophilic bacterium, PS3, with dicyclohexylcarbodiimide. 622 24

ATP induced swelling of isolated yeast mitochondria suspended in an isoosmotic solution of potassium gluconate. Valinomycin stimulated the swelling rate, indicating that K+ influx in the presence of ATP is rate-controlling. This swelling was inhibited by ADP, phosphate (probably acting on the external face of the inner membrane), and Mg2+, which forms a complex with ATP. ATP-induced swelling did not require working F0-F1-ATPase since it was not inhibited by oligomycin and uncoupler. CTP and GTP also induced a swelling. ATP also induced mitochondrial swelling in potassium glutamate, chloride, and acetate but not in phosphate solutions. Sodium, but not ammonium, can replace potassium ion. It is probable that the ATP-channel opening also necessitates an electrogenic cation influx. Respiration also induced swelling of mitochondria suspended in isoosmotic potassium gluconate solution. ATP- or respiration-induced swelling were inhibited equally by N,N'-dicyclohexylcarbodiimide, propranolol, and Zn2+ but not by quinine; all these drugs inhibit the H+/K+ exchange. It was concluded that this unspecific channel is not open under conditions used to measure oxidative phosphorylation. Its physiological role remains unknown.
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PMID:ATP-induced unspecific channel in yeast mitochondria. 752 86

Previous attempts to isolate a stable F0F1-ATPase complex (H(+)-translocating ATPase) from Vibrio parahaemolyticus have been unsuccessful. Using new non-ionic detergents (alkyl thiomaltosides), a stable F0F1 complex with a high specific activity (15-25 units/mg protein) was purified and characterized. The purified F0F1-ATPase consists of eight subunits (alpha, beta, gamma, delta, epsilon, a, b and c). The new detergents, in combination with sucrose (or glycerol), lipid, dithiothreitol and phenylmethylsulfonyl fluoride, effectively stabilized the F0F1 complex. The ATPase activity of the F0F1 complex was greatly increased by anions, such as SO4(2-) and SO3(2-). Sodium ion increased the activity by about 2-fold. Dicyclohexylcarbodiimide, Zn2+, 4-acetamido-4'-isothiocyanostilben-2,2'disulfonate and tetrachlorosalicylanilide inhibited F0F1-ATPase activity. Ethanol, which stimulated F1-ATPase activity, inhibited F0F1-ATPase activity. Methanol, Na3VO4 and bafilomycin A1 did not have any significant effect on F0F1-ATPase activity, although methanol, like ethanol, stimulated F1-ATPase activity.
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PMID:F0F1-ATPase of Vibrio parahaemolyticus: purification using new detergents and characterization. 794 6


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