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)

A mathematical procedure is presented which permits to calculate the steady-state concentrations of AMP, ADP and ATP in an ATP-regenerating assay containing pyruvate kinase and lactate dehydrogenase as auxiliary enzymes. The accuracy of this procedure is demonstrated by the agreement of the calculated concentrations with the experimental data obtained in measurements of mitochondrial ATPase activities. The computer-assisted procedure can be employed (a) to determine extremely low adenine nucleotide concentrations which are difficult to obtain by direct measurements and (b) to adjust and to optimize the assay conditions according to the specific requirements of the experiment, including high concentrations of ATP and prescribed ATP/ADP ratios.
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PMID:A computer assisted method to control the steady state of an ATP-regenerating assay. 275 34

The interaction of inorganic phosphate with native and nucleotide-depleted F1-ATPase was studied. F1-ATPase depleted of tightly bound nucleotides loses the ability to bind inorganic phosphate. The addition of ATP, ADP, GTP and GDP but not AMP, restores the phosphate binding. The nucleotides affecting the phosphate binding to F1-ATPase are located at the catalytic (exchangeable) site of the enzyme. The phosphate is thought to bind to the same catalytic site where the nucleotide is already bound. It is thought that ADP is the first substrate to bind to F1-ATPase in the ATP synthesis reaction.
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PMID:Tightly bound nucleotides affect phosphate binding to mitochondrial F1-ATPase. 285 8

Bidentate cobalt(III)tetraamine adenosine triphosphate [Co(NH3)4ATP] was investigated as an inhibitor of the beef heart mitochondrial F1-ATPase. The compound was found to have a mixed noncompetitive mechanism with a Ki of 0.4 mM and an alpha of 1.4 during ATP hydrolysis. Co(NH3)4ATP also noncompetitively inhibited ATP hydrolysis in the presence of bicarbonate. ITP hydrolysis was similarly affected. Co(NH3)4ATP was also used in dual inhibitor studies with adenylylimidodiphosphate (AMP-PNP) and azide; it was found to be mutually exclusive with AMP-PNP and azide. The compound also protected the F1 from modification by 4-chloro-7-nitrobenzofurazan. These results are discussed in terms of the regulation of the ATP hydrolysis reaction.
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PMID:The effect of Co(III)(NH3)4ATP on the kinetics of beef heart mitochondrial ATPase. 285 40

The possibility that 4-azido-2-nitrophenyl phosphate (ANPP), a photoreactive derivative of inorganic phosphate (Pi) [Lauquin, G., Pougeois, R., & Vignais, P. V. (1980) Biochemistry 19, 4620-4626], could mimic ATP was investigated. ANPP was hydrolyzed in the dark by sarcoplasmic reticulum Ca2+-ATPase in the presence of Ca2+ but not in the presence of ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. ANPP was not hydrolyzed by purified mitochondrial F1-ATPase; however, ADP and ATP protected F1-ATPase against ANPP photoinactivation. On the other hand, the trinitrophenyl nucleotide analogues (TNP-ADP, TNP-ATP, and TNP-AMP-PNP), which bind specifically at the two catalytic sites of F1-ATPase [Grubmeyer, C., & Penefsky, H. (1981) J. Biol. Chem. 256, 3718-3727], abolished Pi binding on F1-ATPase; they do not protect F1-ATPase against ANPP photoinactivation. Furthermore, ANPP-photoinactivated F1-ATPase binds the TNP analogues in the same way as the native enzyme. The Pi binding site of F1-ATPase, which is shown to be photolabeled by ANPP, does not appear to be at the gamma-phosphate position of the catalytic sites.
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PMID:Further investigations on the inorganic phosphate binding site of beef heart mitochondrial F1-ATPase. 285 84

The native tonoplast and the mitochondrial H+-ATPase from oat roots were compared to determine whether the two enzymes have similar mechanisms. H+ pumping in low-density microsomal vesicles reflected activity from the tonoplast-type ATPase, as ATPase activity and ATP-dependent H+ pumping (quinacrine fluorescence quenching) showed similar sensitivities to inhibition by N-ethylmaleimide, N,N'-dicyclohexylcarbodiimide, 4,4'-diisothiocyano-2,2'-stilbene disulfonate, nitrate, quercetin, or 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole. The tonoplast-type ATPase was stimulated by C1-,Br- greater than HCO3- whereas the mitochondrial ATPase was stimulated by HCO3- much greater than C1-,Br-. Both enzymes hydrolyzed ATP preferentially and were inhibited competitively by AMP or ADP. Apart from resistance to azide, the tonoplast-type ATPase was strikingly similar in its inhibitor sensitivities to the mitochondrial ATPase. The insensitivity to vanadate of both enzymes suggests the reaction mechanisms do not involve a covalent phosphoenzyme. Inhibition by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole and N-ethylmaleimide and protection by ATP suggests tyrosine and cysteine residues are in the catalytic site of the tonoplast ATPase. The mitochondrial ATPase was 100 times more sensitive to N,N'-dicyclohexyl-carbodiimide inhibition than the tonoplast H+-ATPase. These results suggest the tonoplast and the mitochondrial H+-ATPases share common steps in their catalytic and vectorial reaction mechanisms, yet sufficient differences exist to indicate they are two distinct ATPases.
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PMID:Similarities and differences between the tonoplast-type and the mitochondrial H+-ATPases of oat roots. 286 67

Beef heart mitochondrial ATPase (F1) catalyzes the hydrolysis of the ATP analog adenyl-5-yl imidodiphosphate (AMP-PNP). The reaction products are inorganic phosphate and adenyl-5-yl phosphoramidate (AMP-PN) as determined by HPLC analysis. The hydrolysis occurs in both the presence and absence of added divalent metal ions and is stimulated by potassium. The kinetic properties of the hydrolytic reaction depend markedly on the identity of the added divalent metal. GMP-PNP and AMP-CPP are also hydrolyzed, while AMP-PCP is not. Adenyl-5-yl phosphoramidate is a potent effect of beef heart mitochondrial ATPase activity. Based on these data, a reinterpretation of work based on the assumption that AMP-PNP is not hydrolyzed is presented.
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PMID:Hydrolysis of adenyl-5-yl imidodiphosphate by beef heart mitochondrial ATPase. 286 12

F1-ATPase of rat liver was examined for its capacity to interact with both metal ions and nucleotides and for the effect of covalent ATPase inhibitors on these interactions. As isolated, rat liver F1 contains about 2 mol of Mg2+/mol of F1, 1 mol of which can be removed or exchanged. The remaining mole of Mg2+ per mole of F1 remains very tightly associated with F1 and is recovered in the alpha gamma fraction after cold denaturation. Rat liver F1 also contains as isolated a nearly equivalent amount of nucleotide (approximately 1.7 mol/mol of F1) which is readily removed by incubation at room temperature followed by column centrifugation. The "2 Mg2+ enzyme" binds almost 3 mol of 5'-adenylyl imidodiphosphate (AMP-PNP)/mol of F1 in the presence or absence of added divalent cation. When divalent cation is present as Co2+, an equivalent activator to Mg2+ in the ATPase reaction, 1 mol of F1 binds 3 mol of both AMP-PNP and Co2+. under these conditions, the very tight Mg2+ site remains loaded, the exchangeable Mg2+ site is replaced with AMP-PNPCo, and two additional AMP-PNPCo sites are filled. At this point, ADP can be loaded onto the enzyme as a fourth nucleotide at a site separate and distinct from the AMP-PNP sites. Significantly, rat liver F1 contains only a single readily detectable ADP binding site in the presence or absence of divalent cation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ligand binding studies of the F1 moiety of rat liver ATP synthase: implications about the enzyme's structure and mechanism. 288 76

The Mg2+-ATPase activities of bovine adrenal chromaffin granules were studied in highly purified preparations of granule ghosts and in intact organelles. The overall ATPase activity (150-250 nmol ADP min-1 mg-1) of the granule ghost preparations was inhibited less than 5% by the bathophenanthroline chelate of Fe(II), a potent inhibitor of mitochondrial F1-ATPase. This small inhibition can be accounted for by a very minor contamination with mitochondria or mitochondrial fragments. The overall ATPase activity of native granule ghosts was inhibited about 75% by N-ethylmaleimide, with half-maximal inhibition at about 20 microM. The titration curve was slightly shifted towards higher concentrations as compared to the inhibition curve for the proton pump activity, which was completely inhibited at 25 microM. N,N'-Dicyclohexylcarbodiimide inhibited the overall ATPase activity by 75-80% at 1.1 mumol/mg protein, a concentration that completely abolished the proton pump activity. Low concentrations (10 microM) of vanadate inhibited the overall ATPase activity by about 15% but had no effect on the proton pump activity, which was partly inhibited only at higher vanadate concentrations. Our attempts to assign a function to the vanadate-sensitive and N-ethylmaleimide-insensitive ATPase have so far been unsuccessful. In particular, our assay for ATP diphosphohydrolase activity was negative, although the chromaffin granule ghosts revealed a low Mg2+-ADPase activity (11.8 nmol AMP min-1 mg-1 protein). In intact chromaffin granules the specific Mg2+-ATPase activity (50-70 nmol ADP min-1 mg-1) was stimulated 2-fold by uncouplers, as compared to 1.6-1.7-fold in granule ghosts. The degree of energy coupling was rather independent of the external pH (6.5 less than pH less than 8.0) and temperature (20-45 degrees C). As expected, partial inhibition (about 15%) of the overall ATPase activity by 10 microM vanadate increased the ATPase control ratio. ADP was found to be a potent inhibitor of the proton pump activity with MgATP as the substrate, and the effect can partly be explained by a competitive type of inhibition of the hydrolytic reaction. This effect of ADP explains some of the kinetic data reported for MgATP-dependent (H+-ATPase-dependent) reactions in this organelle, notably the energy-dependent accumulation and storage of catecholamines.
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PMID:Studies on Mg2+-dependent ATPase in bovine adrenal chromaffin granules. With special reference to the effect of inhibitors and energy coupling. 288 84

Internal homology units of F1-ATPase epsilon and gamma subunits were searched by computer-aided methods. The epsilon in E. coli (EC) and maize chloroplast (Ch1) was found to consist of three homologous domains, named domains I, II and III (amino acids 1-47, 48-95 and 96-139 for EC). The gamma in E. coli was demonstrated to have at least six homologous domains, tentatively named here domains I-III and V-VII (I = aa 1-23, II = 26-69, III = 71-112, V = 150-192, VI = 196-242, VII = 285-329), with leaving a region IV (113-149) unclassified. Adenylate kinases (AK's) in pig and E. coli were found to have three internal homology units, named I, I' and II (I = aa 1-47, I' = 48-79, II = 80-124 for pig). Statistical evaluations and dot matrix analyses at both base and amino acid sequence levels have confirmed that all of these repeating units, being about 46 amino acids long, are homologous with one another. Of these, epsilon III, II, gamma VII and AK II domains were most conservative and some of them showed homology to core enzyme alpha and an internal repeating unit of tryptophanyl-tRNA synthetase (Trp-RS). Thus these homology unit-encoding gene segments must be relics of a primodial gene.
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PMID:A most primitive primodial gene as a building block of the genes for the adenylate kinase, F1-ATPase subunits (epsilon and gamma), aminoacyl-tRNA synthetase, and core enzyme subunits. 288 90

The effect of exposure to adenine nucleotides on the dissociation of phosphate bound to beef heart mitochondrial F1-ATPase (F1) has been studied using a layered Sephadex centrifuge column method. The order of effectiveness of nucleotides in facilitating Pi dissociation from F1 was ATP greater than AMP-PNP much greater than ADP (where AMP-PNP indicates adenosine 5'-(beta,gamma-imido)triphosphate) when phosphate had bound to F1 as Pi from the medium. When ATP was present in amounts substoichiometric to F1, essentially all of the ATP present bound to F1, and the molar ratio of Pi released to ATP bound was near one. Under similar conditions AMP-PNP bound equally well to F1, but in order to effect similar amounts of Pi release it was necessary to use approximately 10 times as much AMP-PNP as ATP. The order of effectiveness of nucleotides in facilitating dissociation of phosphate which had bound to F1 as the gamma-phosphate of ATP was ATP = AMP-PNP much greater than ADP. In this case ATP and AMP-PNP were as effective in facilitating phosphate dissociation as was ATP in the case in which phosphate had bound to F1 as Pi. It is concluded that when phosphate has bound to F1 as Pi, binding of one molecule of ATP or more than one molecule of AMP-PNP are sufficient to facilitate dissociation of phosphate. When phosphate has bound to F1 as the gamma-phosphate of ATP, binding of one molecule of either ATP or AMP-PNP is sufficient to facilitate dissociation of phosphate.
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PMID:Dissociation of phosphate from beef heart mitochondrial F1-ATPase. Effect of adenine nucleotides. 288


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