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)

1. Thermostable membrane vesicles which were capable of active transport of alanine dependent on either respiration or an artificial membrane potential were isolated from the thermophilic aerobic bacterium PS3. 2. Uptake of alanine was dependent on the oxidation of ascorbate-phenazine methosulfate or on generated or exogenous NADH, but succinate and malate failed to drive the uptake. The optimum temperature for respiration-driven uptake of alanine was 45 to 60 degrees. 3. Potassium ion-loaded vesicles were prepared by incubating vesicles at 55 degrees in 0.5 M potassium phosphate. The addition of valinomycin elicited rapid and transient uptake of alanine under the test conditions. Uptake of alanine in response to valinomycin was progressively enhanced by the addition of dicylohexylcarbodiimide, but was completely abolished in the presence of a proton conductor or synthetic permeable cation. The effect of dicyclohexylcarbodiimide was dependent on its concentration and was maximal at a concentration of 0.4 mM. 4. The proton permeability of membrane vesicles was reduced by the addition of dicyclohexylcarbodiimide. A small but significant difference was found in the initial rates of proton uptake in the presence of dicyclohexylcarbodiimide with and without alanine. The results suggest that protons alanine are transported simultaneously in a stoichiometric ratio of 1 : 1. 5. The uptake of alanine was also driven by a pH gradient induced by an instantaneous pH drop in a suspension of alkali-loaded vesicles. Thus, alanine accumulation was driven not only by an electrical potential but also by a pH gradient. 6. Addition of ATP resulted in the inhibition of alanine uptake dependent on artificial membrane potential. ATP hydrolysis by membrane ATPase created a membrane potential which was inside-positive, and this might decrease the effective membrane potential (generated by K+ efflux mediated by valinomycin) available to drive alanine uptake.
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PMID:Active transport of alanine by thermostable membrane vesicles isolated from a thermophilic bacterium. 0 39

1. Generation of a transmembrane electric potential difference by oligomycin-sensitive ATPase complex, incorporated into spherical or planar phospholipid membrane, has been demonstrated. To this end, penetrating anion probe and direct voltmeter measurement of electric potential across phospholipid membrane were used. It was found that ATP-induced electric response is sensitive to oligomycin and protonophorous uncouplers. 2. The effect of variations in the phospholipid component of proteoliposomes on the electric generation was studied. It was revealed that the usage of mitochondrial phospholipids and phosphatidylethanolamine allows the highest values of membrane potential to be obtained in the case of ATPase proteoliposomes. In the case of cytochrome oxidase and bacteriorhodopsin proteoliposomes, phosphatidylserine was also shown to be quite suitable. Phosphatidylcholine was absolutely ineffective in all cases. 3. In proteoliposomes, containing both ATPase and bacteriorhodopsin, ATP and light induced generation of the electric field of the same direction. 4. In ATPase + cytochrome oxidase proteoliposomes, ATP hydrolysis and ascorbate oxidation was found to support electric generation of the same direction if cytochrome c was inside vesicles. Oxidation via external cytochrome c resulted in formation of electric field of the direction, opposite to that induced by ATP hydrolysis. 5. The data obtained in experiments with proteoliposomes of different types are discussed. The conclusion is made that conversion of energy of different resources into electric form is a common feature of membraneous energy transducers, which is in agreement with the Mitchellian principle of cellular energetics.
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PMID:Reconstitution of biological molecular generators of electric current. H+-ATPase. 1 Dec 15

1. DL-8-Methyldihydrolipoate was shown to be a potent inhibitor of mitochondrial oxidative phosphorylation and ATP-driven energy-linked reactions. 2. ADP-stimulated respiration utilizing pyruvate + malate and succinate in both ox heart and rat liver mitochondria is inhibited; oxidative phosphorylation using pyruvate + malate, succinate and ascorbate + NNN'N'-tetramethyl-p-phenylenediamine as substrates is also inhibited; uncoupler-stimulated respiration is unaffected regardless of the substrate used. 3. Mitochondrial oligomycin-sensitive adenosine triphosphatase is inhibited in both the membrane-bound form and the purified detergent-dispersed preparation. 4. ATP-driven transhydrogenase and the ATP-driven energy-linked reduction of NAD+ by succinate in ox heart submitochondrial particles are inhibited, whereas the respiratory-chain-driven transhydrogenase is unaffected. 5. DL-8-Methyl-lipoate has no immediate effect on the above reactions, demonstrating the requirement for the reduced form for inhibition. 6. The inhibitory properties of DL-8-methyldihydrolipoate are analogous to those of oligomycin and provide further evidence of a role for lipoic acid in oxidative phosphorylation.
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PMID:Studies of energy-linked reactions. Inhibition of oxidative phosphorylation by DL-8-methyldihydrolipoate. 14 82

A technique for selecting mutants of Escherichia coli in which the proton-translocating sector of the adenosine triphosphatase (ATPase) complex has been inactivated is reported. The procedure uses a strain of E. coli (NR-70) lacking the extrinsic (F1) sector of the ATPase complex and which in consequently permeable to protons (B. P. Rosen, J. Bacteriol. 116:1124--1129, 1973). After growing strain NR-70 under noninducing conditions for the lac operon, cells were mutagenized and plated on minimal medium containing low concentrations of lactose. Several mutants of strain NR-70 were isolated as large colonies on these plates, apparently because they could concentrate lactose more efficiently. A description of one of the mutants, strain KW-1, is reported here. The most distinguishing difference in growth properties of the two strains was that, when transferred to medium containing low concentrations of lactose, strain KW-1 induced the lac operon with a shorter lag time than strain NR-70. The mutation in strain KW-1 leading to more rapid growth on lactose was cotransducible with the asn and unc loci, at 83 min on the E. coli genetic map. Intact cells of strain KW-1 actively transported L-proline as well as did wild-type cells, whereas cells of strain NR-70 were markedly deficient in L-proline transport. The improvement in the transport capacity of strain KW-1 correlated with a marked decrease in proton permeability relative to that of strain NR-70. Based on an acid-base pulse technique that measured the proton conductance of the membranes of intact cells, strain NR-70 was at least 10 times more permeable to protons than was the wild type, whereas strain KW-1 was only 2 times more permeable. The transport properties and proton conductance were also compared with membrane vesicles prepared by osmotic shock. With either D-lactate or ascorbate-N-methylphenazonium methosulfate as respiratory substrates, vesicles of strain KW-1 transported L-proline much more rapidly than did vesicles of strain NR-70, but still at rates less rapid than those of the wild type. The passive proton conductance of the membrane vesicles was quantitated by measuring the rate of H+ influx into vesicles in response to a valinomycin-generated K+ diffusion potential. The proton permeability of vesicles of strain KW-1 was reduced 1.5-fold relative to vesicles of strain NR-70, but these vesicles were still four times more permeable to protons than was the wild type. Vesicles of strain KW-1 corresponded to wild-type vesicles treated with 0.5 micrometer carbonylcyanide m-chlorophenylhydrazone (CCCP) and vesicles of strain NR-70 corresponded to wild-type vesicles treated with 1.4 micrometer CCCP. Treatment of wild-type vesicles with these concentrations of CCCP caused decreases in transport comparable to those observed in the mutants. Strain KW-1 lacked ATPase activity. Cross-reacting material to F1-ATPase was not found in strain KW-1 by double immunodiffusion analysis.
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PMID:Method for isolation of Escherichia coli mutants with defects in the proton-translocating sector of the membrane adenosine triphosphatase complex. 15 9

It was shown that when injected into a suspension of sarcoplasmic reticulum (SR) vesicles phosphatidyl ethanol-amine hydroperoxide (HP) slightly activated Ca++-dependent ATPase and increased the permeability of SR membranes for Ca++ during the enzyme function. Linoleic acid HP had no effect on the parameters of the enzymatic Ca++- transporting system (activity of Ca++-dependent ATPase, Ca/ATP ratio, rate of Ca++ efflux) in the SR membranes due to its insufficient incorporation into the SR fragments. It is concluded that among the primary molecular products of lipid peroxidation (free fatty acid HP, phospholipid HP) induced both in vitro (by the Fe++ + ascorbate system) and in vivo (ischemia, E-avitaminosis), only the phospholipid HPs were modifiers of Ca++ transport in the SR membranes.
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PMID:[Disruption of the Ca++ transport enzyme system in sarcoplasmic reticulum membranes upon exposure to phospholipid hydroperoxides and fatty acid hydroperoxides]. 15 51

Rhodopseudomonas palustris is grown photosynthetically on thiosulfate. As pointed out earlier, the chromatophore deficient cell-free fraction S-144,000 catalyzes the thiosulfate-linked ATP-dependent reversal of electron transfer in anaerobiosis, thus providing reducing equivalents in the form of NADH. Under aerobic conditions, this fraction also catalyzes the oxidation of NADH, ferro-cytochrome c, or ascorbate. ATP, ADP, and PPi are active in retarding the aerobic electron flow. The electron retardation is stimulated by the addition of Mg2+ due to a Mg2+-stimulated ATPase present. The ATPase system in S-144,000 hydrolyzes ATP, ADP, and PPi. Similarly, ATP or ADP, or even PPi can function as energy sources in order to achieve the reduction of pyridine nucleotide. The ATPase turnover is diminished by NADH or NAD+. Admixture of ascorbate results in an increased ATPase activity. Exactly the enhanced amount of adenine nucleotide hydrolysis caused by the addition of ascorbate is inhibited by cyanide.
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PMID:Respiratory electron flow and ATPase system in photosynthetically grown Rhodopseudomonas palustris. 17 Jul 51

Out of other functions performed by vitellaria in digenetic trematodes, their role in the formation of shell globules and shell membrane of the capsule, as well as in the excretion of iron with the help of vitamin C is very important. The present histochemical work shows the localization of certain enzymes in different parts of the reproductive system of ten species of trematodes viz.: Neopronocephalus triangularis Mehra, 1932; Glossimetra orientalis Mehra, 1937; Orientodiscus lobatus Srivastava, 1938; Eumegacetes artemii Mehra, 1935; Ganeo tigrinus mehra et Negi, 1928; Encyclometra caudata Dollfus, 1928; Thapariella udaipurensis Gupta and Sharma, 1970; Paradistomoides indicum Narain et Das, 1929; Patagifer wesleyi Verma, 1936; Proalarioides tropidonotus Vidyarthi, 1937 and indicates their functional significance. The hydrolytic enzymes (alkaline phosphatase, acid phosphatase, 5-nucleotidase and ATPase) are suggestive of their involvement in the uptake of certain nutrients, glycogen and lipoprotein being very significant among others. The four enzymes could also be detected in testes, ovary, uterus, cirrus sac and egg shell. The possible functional significance of each enzyme has been discussed.
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PMID:Histochemical studies on the distribution of alkaline phosphatase, acid phosphatase, 5-nucleotidase and ATPase in various reproductive tissues of certain digenetic trematodes. 18 33

1. Cytochrome oxidase was incorporated into preformed liposomes containing phosphatidylserine. When confronted with a mixture of liposomes, some containing phosphatidylserine and some without it, the enzyme was incorporated only into the phosphatidylserine-containing liposomes. 2. The hydrophobic proteins of the oligomycin-sensitive ATPase incubated in the presence of a mixture of liposomes with and without cytochrome oxidase were preferentially incorporated into cytochrome oxidase-containing liposomes. This selectivity was abolished by either cytochrome c or ascorbate. 3. Cytochrome oxidase incubated in the presence of a mixture of liposomes with and without the hydrophobic proteins of the ATPase was preferentially incorporated into liposomes that did not contain the hydrophobic proteins. 4. Cytochrome oxidase and the oligomycin-sensitive ATPase were preferentially incorporated into pure liposomes over bacteriorhodopsin-containing vesicles. 5. Reduced coenzyme Q (QH2)-cytochrome c reductase was incorporated randomly when incubated in the presence of a mixture of pure liposomes and liposomes containing the hydrophobic proteins of the ATPase complex. 6. The significance of the incorporation procedure as a model for membrane biogenesis is discussed.
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PMID:Selective incorporation of membrane proteins into proteoliposomes of different compositions. 19 31

Fragmented sarcoplasmic reticulum (SR) was reacted with a thiol-directed spin label, N-(1-oxyl-2,2,6,6,-tetramethyl-4-piperidinyl)maleimide, under various conditions. It was found that ATP inhibited the binding of the label to SR protein in the initial phase of the reaction, but as the incubation time was extended up to 18 h, the amount of label bound to SR protein in the control and ATP-containing samples became almost identical. The Ca2+-dependent ATPase control and ATP-containing samples became almost identical The Ca2+-dependent ATPase (ATP phosphohydrolase [EC 3.6.1.3]) of SR was protected by the presence of ATP during incubation with relatively low concentrations of spin label, irrespective of the total amount of label bound, although with increasing concentration of bound label the ATPase activity decreased. Deoxycholate slightly reduced the rotational freedom of the label bound to SR protein and decreased the initial rate of quenching of protein-bound nitroxide by ascorbate. From an analysis of these results, it was concluded that the binding of deoxycholate to protein decreases the accessibility of ascorbate to the protein-bound label.
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PMID:Spin-labeling of adenosine triphosphatase in sarcoplasmic reticulum membrane and change in the state of the spin labels induced by deoxycholate. 20 Jun 8

1. The properties of membrane vesicles from the extreme thermophile Bacillus caldolyticus were investigated. 2. Vesicles prepared by exposure of spheroplasts to ultrasound contained cytochromes a, b and c, and at 50 degrees C they rapidly oxidized NADH and ascorbate in the presence of tetramethyl-p-phenylenediamine. Succinate and l-malate were oxidized more slowly, and dl-lactate, l-alanine and glycerol 1-phosphate were not oxidized. 3. In the absence of proton-conducting uncouplers the oxidation of NADH was accompanied by a net translocation of H(+) into the vesicles. Hydrolysis of ATP by a dicyclohexylcarbodi-imide-sensitive adenosine triphosphatase was accompanied by a similarly directed net translocation of H(+). 4. Uncouplers (carbonyl cyanide p-trifluoromethoxyphenylhydrazone or valinomycin plus NH(4) (+)) prevented net H(+) translocation but stimulated ATP hydrolysis, NADH oxidation and ascorbate oxidation. The last result suggested an energy-conserving site in the respiratory chain between cytochrome c and oxygen. 5. Under anaerobic conditions the reduction of cytochrome b by ascorbate (with tetramethyl-p-phenylenediamine) was stimulated by ATP hydrolysis, indicating an energy-conserving site between cytochrome b and cytochrome c. However, no reduction of NAD(+) supported by oxidation of succinate, malate or ascorbate occurred, neither did it with these substrates in the presence of ATP under anaerobic conditions, suggesting that there was no energy-conserving site between NADH and cytochrome b. 6. Succinate oxidation, in contrast with that of NADH and ascorbate, was strongly inhibited by uncouplers and stimulated by ATP hydrolysis. These effects were not observed when phenazine methosulphate, which transfers electrons from succinate dehydrogenase directly to oxygen, was present. It was concluded that in these vesicles the oxidation of succinate was energy-dependent and that the reoxidation of reduced succinate dehydrogenase was dependent on the outward movement of H(+) by the protonmotive force. 7. In support of the foregoing conclusion it was shown that the reduction of fumarate by NADH was an energy-conserving process. 8. If the activities of vesicles accurately represent those of the intact organism it appears that in B. caldolyticus the reduction of fumarate to succinate at the expense of reducing equivalents from NADH is energetically favoured over succinate oxidation even under aerobic conditions. This may be related to the need for an ample supply of succinate for haem synthesis in order to provide cytochromes for the organism.
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PMID:The oxidative activities of membrane vesicles from Bacillus caldolyticus. Energy-dependence of succinate oxidation. 20 11


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