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)

The interaction between pure transhydrogenase and ATPase (Complex V) from beef heart mitochondria was investigated with transhydrogenase-ATPase vesicles in which the two proteins were co-reconstituted by dialysis or dilution procedures. In addition to phosphatidylcholine and phosphatidylethanolamine, reconstitution required phosphatidylserine and lysophosphatidylcholine. Transhydrogenase-ATPase vesicles catalyzed a 20-30-fold stimulation of the reduction of NADP+ or thio-NADP+ by NADH and a 70-fold shift of the apparent equilibrium expressed as the nicotinamide nucleotide ratio [NADPH][NAD+]/[NADP+][NADH]. In both of these respects, the transhydrogenase-ATPase vesicles were severalfold more efficient than beef heart submitochondrial particles. By measuring the ATP-driven transhydrogenase and the oligomycin-sensitive ATPase activities simultaneously and under the same conditions at low ATP concentrations, i.e. below 15 microM, the ATP-driven transhydrogenase/oligomycin-sensitive ATPase activity ratio was found to be about 3. This value is consistent with the stoichiometries of three protons translocated per ATP hydrolyzed and one proton translocated per NADPH formed and with a mechanism where the two enzymes interact through a delocalized proton-motive force.
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PMID:Energy-linked nicotinamide-nucleotide transhydrogenase. Characterization of reconstituted ATP-driven transhydrogenase from beef heart mitochondria. 355 83

Rhodamine 123, a laser dye, has been demonstrated to inhibit import of the precursor to pyridine dinucleotide transhydrogenase into mitochondria in rat liver cells. When rat hepatocytes were labeled with 35[S] methionine in the presence of 0.4 mM rhodamine 123, the precursor to transhydrogenase was found to have a half-life in the cytoplasm of 15 minutes as opposed to a half-life of 1-2 minutes when cells were radiolabeled in the absence of the dye. To clarify the mechanism of import inhibition, studies were initiated to assess the effect of rhodamine 123 on mitochondrial respiration. Upon addition of the dye to a mitochondrial suspension, respiration was initially enhanced, then inhibited. The inability of FCCP, a classical uncoupler, to enhance respiration during the inhibitory phase suggests that rhodamine 123 is primarily inhibiting respiration through the electron transport system rather than through the ATPase. These results suggest that rhodamine 123 may inhibit import of the transhydrogenase precursor into mitochondria by disrupting components in the mitochondrial membrane necessary for efficient import.
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PMID:Rhodamine 123 inhibits import of rat liver mitochondrial transhydrogenase. 357 20

1. A new mutant strain (AN228) of Escherichia coli K12, unable to couple phosphorylation to electron transport, has been isolated. The mutant allele (unc-405), in strain AN228, was found to map near the uncA and uncB genes at about minute 74 on the E. coli genome. 2. A transductant strain (AN285) carrying the unc-405 allele is similar to the uncA and uncB mutants described previously in that it is unable to grow on succinate, gives a low aerobic yield on limiting concentrations of glucose, has a normal rate of electron transport, is unable to couple phosphorylation to electron transport, and lacks ATP-dependent transhydrogenase activity. 3. Strain AN285 (unc-405) is similar to an uncA mutant, but different from an uncB mutant, in that it is unable to grow anaerobically in a glucose-mineral-salts medium, and membrane preparations do not have Mg(2+)-stimulated adenosine triphosphatase activity. 4. Strain AN285 (unc-405) does not form an aggregate analogous to the membrane-bound Mg(2+)-stimulated adenosine triphosphatase aggregate found in normal cells. In this respect it differs from strain AN249 (uncA(-)), which forms an inactive membrane-bound Mg(2+)-stimulated adenosine triphosphatase aggregate.
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PMID:Oxidative phosphorylation in Escherichia coli K12. An uncoupled mutant with altered membrane structure. 415 Aug 11

The Mg(2+)- and Ca(2+)-stimulated ATPase (EC 3.6.1.3; ATP phosphohydrolase) (bacterial coupling factor) was purified from two strains of E. coli by two different procedures: (a) method of Nelson, Kanner, and Gutnick [Proc. Nat. Acad. Sci. USA (1974) 71, 2720-2724] and (b) a modified procedure described in this paper. The ATPase purified from E. coli K12 (lambda) by the first procedure had 4 subunits (alpha, beta, gamma, and epsilon). It did not bind to a deficient membrane, nor did it reconstitute ATP-driven transhydrogenase activity. Our modified procedure (b) yielded 5 subunits (alpha, beta, gamma, delta, and epsilon). This ATPase could bind to a deficient membrane and reconstitute ATP-driven transhydrogenase. This finding suggests that the delta subunit is required for the reaction with the membrane. The molecular weight of the 4-subunit ATPase was significantly lower than that of the 5-subunit ATPase, as judged by equilibrium centrifugation. The specific ATPase activities of both preparations were about the same. These two procedures were also applied to E. coli ML308-225.
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PMID:Purification and properties of reconstitutively active and inactive adenosinetriphosphatase from Escherichia coli. 415 28

A review of actions of vertebrate sex hormones is presented. The main topics of discussion are: 1) intracellular proteins binding sex hor mones and their metabolites (estrogen uptake by intact normal cells; upt ake of estrogens by mammary gland, and by mammary and other tumors; ster eospecific estrogen-binding proteids in responsive tissues; uptake of androgens by animal cells and formation of 5alpha-androstane and other derivatives; 5alpha-dihydrotestosterone-binding proteids; disposition of progesterone in various tissues); 2) testicular feminization syndrome; 3) effects of sex hormones on organ cultures, with comments on deoxyribonucleic acid synthesis and cell division in relation to tissue growth; 4) estrogen-mediated pyridine nucleotide transhydrogenase reactions; 5) intracellular "2nd messengers" and sex hormone action (polyamines); 6) physiological actions of 5beta-hydrogenated steroid metabolites and effects of sex hormones on erythropoiesis; 7) influences of sex hormones on structure, metabolism, and functions of reproductive organs (ribonucleic acid - RNA - and protein synthesis; RNA preparations and genital tissue growth; androgens and cation-activated adenosinetriphosphatase reactions; uptake of glucose and glycogen synthesis; mitochondrial reactions; gonadal hormones and sebaceous glands); and 8) medieval Chinese protoendocrinology.
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PMID:Actions of vertebrate sex hormones. 415 16

The membrane adenosine triphosphatase (E.C. 3.6.1.3) from Escherichia coli has been solubilized with Triton X-100 and purified to near homogeneity. The purified enzyme has a sedimentation coefficient of 12.9S in a sucrose gradient, corresponding to a molecular weight of about 360,000. On electrophoresis in gels containing sodium dodecyl sulfate, it dissociates into subunits with apparent molecular weights of 60,000, 56,000, 35,000, and 13,000. The purified enzyme loses activity and breaks down into subunits when stored in the cold. Guanosine 5'-triphosphate and inosine 5'-triphosphate are alternative substrates. Ca(2+) and, to a small extent, Co(2+) or Ni(2+) will substitute for Mg(2+) in the reaction. The K(m) for Mg-adenosine triphosphate of the membrane-bound enzyme is 0.23 mM, and for the pure enzyme it is 0.29 mM. Azide is a noncompetitive inhibitor of both the membrane-bound enzyme and the pure enzyme. P(i) is a noncompetitive inhibitor of the solubilized enzyme. An antibody to the purified enzyme was obtained from rabbits. The antibody inhibits the solubilized enzyme and virtually all of the adenosine triphosphate hydrolysis by membranes from cells grown aerobically or anaerobically. The antibody also inhibits the adenosine triphosphate-stimulated pyridine nucleotide transhydrogenase (E.C. 1.6.1.1) of the E. coli membrane.
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PMID:Energy-transducing adenosine triphosphatase from Escherichia coli: purification, properties, and inhibition by antibody. 426 35

1. We have isolated a mutant of Escherichia coli K12 (strain AN295) that forms de-repressed amounts of Mg(2+),Ca(2+)-stimulated adenosine triphosphatase. 2. The Mg(2+),Ca(2+)-stimulated triphosphatase activity was separated from membrane preparations from strain AN295 by extraction with 5mm-Tris-HCl buffer containing EDTA and dithiothreitol, resulting in a loss of the ATP-dependent transhydrogenase activity. The non-energy-linked transhydrogenase activity remained in the membrane residue. 3. The solubilized Mg(2+),Ca(2+)-stimulated adenosine triphosphatase activity from strain AN295 was partially purified by repeated gel filtration. The addition of the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase to the membrane residue from strain AN295 reactivated the ATP-dependent transhydrogenase activity. 4. Strain AN296, lacking Mg(2+),Ca(2+)-stimulated adenosine triphosphatase activity, was derived by transducing the mutant allele, uncA401, into strain AN295. The ATP-dependent transhydrogenase activity was lost but the non-energy linked transhydrogenase was retained. 5. The ATP-dependent transhydrogenase activity in membrane preparations from strain AN296 (uncA(-)) could not be re-activated by the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase from strain AN295. However, after extraction by 5mm-Tris-HCl buffer containing EDTA and dithiothreitol, the ATP-dependent transhydrogenase activity could be re-activated by the addition of the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase from strain AN295 to the membrane residue from strain AN296 (uncA(-)).
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PMID:Reconstitution of the energy-linked transhydrogenase activity in membranes from a mutant strain of Escherichia coli K12 lacking magnesium ion- or calcium ion-stimulated adenosine triphosphatase. 426 1

1. Membrane preparations from both uncA(-) and uncB(-) mutant strains of Escherichia coli K12, in which electron transport is uncoupled from phosphorylation, were fractionated by washing with a low-ionic-strength buffer. The fractionation gave a ;5mm-Tris wash' and a ;membrane residue' from each strain. This technique, applied to membranes from normal cells, separates the Mg(2+),Ca(2+)-stimulated adenosine triphosphatase activity from the membrane-bound electron-transport chain and the non-energy-linked transhydrogenase activity. 2. Reconstitution of both oxidative phosphorylation and the ATP-dependent transhydrogenase activity was obtained by a combination of the ;membrane residue' from strain AN249 (uncA(-)) with the ;5mm-Tris wash' from strain AN283 (uncB(-)). 3. Valinomycin plus NH(4) (+) inhibited oxidative phosphorylation both in membranes from a normal strain of E. coli and in the reconstituted membrane system derived from the mutant strains. 4. The electron-transport-dependent transhydrogenase activity was located in the membrane residue and was de-repressed in both the mutant strains. 5. The spatial and functional relationships between the proteins specified by the uncA and uncB genes and the transhydrogenase protein are discussed.
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PMID:Reconstitution of oxidative phosphorylation and the adenosine triphosphate-dependent transhydrogenase activity by a combination of membrane fractions from unCA- and uncB- mutant strains of Escherichia coli K12. 427 44

1. The effects of dicyclohexylcarbodi-imide, oligomycin A and aurovertin on enzyme systems related to respiratory-chain phosphorylation were compared. Dicyclohexylcarbodi-imide and oligomycin A have very similar functional effects, giving 50% inhibition of ATP-utilizing and ATP-generating systems at concentrations below 0.8nmole/mg. of submitochondrial-particle protein. Aurovertin is a more potent inhibitor of ATP synthesis, giving 50% inhibition at 0.2nmole/mg. of protein. However, aurovertin is a less potent inhibitor of ATP-utilizing systems: the ATP-driven energy-linked nicotinamide nucleotide transhydrogenase is 50% inhibited at 3.0nmoles/mg. of protein and the ATP-driven reduction of NAD(+) by succinate is 50% inhibited at 0.95nmole/mg. of protein. 2. With EDTA-particles (prepared by subjecting mitochondria to ultrasonic radiation at pH9 in the presence of 2mm-EDTA) the maximum stimulation of the ATP-driven partial reactions is effected by similar concentrations of oligomycin A and dicylcohexylcarbodi-imide, but the latter is less effective. The stimulatory effects of suboptimum concentrations of dicyclohexylcarbodi-imide and oligomycin A are additive. Aurovertin does not stimulate these reactions or interfere with the stimulation by the other inhibitors. 3. Dicyclohexylcarbodi-imide and oligomycin A stimulate the aerobic energy-linked nicotinamide nucleotide transhydrogenase of EDTA-particles, but the optimum concentration is higher than that required for the ATP-driven partial reactions. Aurovertin has no effect on this reaction. 4. The site of action of dicyclohexylcarbodi-imide is in CF(0), the mitochondrial fraction that confers oligomycin sensitivity on F(1) mitochondrial adenosine triphosphatase.
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PMID:A comparison of the effects of NN'-dicyclohexylcarbodi-imide, oligomycin A and aurovertin on enrgy-linked reactions in mitochondria and submitochondrial particles. 429 26

1. Energy-linked and non-energy-linked transhydrogenase activities were assayed in membrane preparations from normal Escherichia coli K 12 and from various mutant strains. 2. The energy-linked transhydrogenase, which uses ATP as energy source, was dependent for activity on the presence of a functional Mg(2+)+Ca(2+)-stimulated adenosine triphosphatase. 3. Neither of the quinones formed by E. coli, namely ubiquinone-8 and menaquinone-8, was required for normal ATP-dependent energy-linked transhydrogenase activity. 4. The energy-linked transhydrogenase was inhibited by piericidin A at a site unrelated to the sites of inhibition of the electron-transport chain by piericidin A.
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PMID:The energy-linked transhydrogenase reaction in respiratory mutants of Escherichia coli K12. 433 91


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