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

---

Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. A procedure for the purification of ATPase extracted by chloroform from baker's yeast (Saccharomyces cerevisiae) is reported. The yield based on submitochondrial particles was 55% and the purification was 100-fold. The isolated complex was homogenous as assessed by gel filtration, ion-exchange chromatography, sedimentation in sucrose gradient and in the analytical ultracentrifuge. The molecular weight determined by gel filtration was 400000 +/- 20000. Ultracentrifugation yielded s020,w = 12.50 +/- 0.13 S and the laser light scattering study gave a diffusion coeficient of D20w - 2.92 X 10(-7) cm2 s-1. The amino acid composition as well as absorption, fluorescence, and circular dichroism spectra, from which the helicity of 39% was evaluated, are given. 2. On polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate, six components with molecular weights of 58500(alpha), 55000 (beta), 42000, 34000 (gamma), 10000(delta), and 8600 (epsilon) were observed with a stoichiometry of 3:3:1:1:1:1. The amino acid composition is given for alpha + beta and gamma as well as delta and epsilon components. 3. The maximum specific activity of the enzyme was 200 U/mg under the optimum conditions. The enzyme was inactivated by incubation at 0 degrees C and strongly inhibited by the antibiotic Dio-9 but not by oligomycin and N, N'-dicyclohexyl-carbodiimide. The effects of kinetic parameters and anions on the enzyme are reported. Two active sites for Mg-ATP with Km values of 0.045mM and 0.37mM and a single activie site for Mg-ITP with Km = 0.179mM were found. A study of the temperature dependence of the maximum activity revealed a straight line in the Arrhenius plots with an activation energy of 11.0 kcal/mol (= 46 kH/mol).
...
PMID:Mitochondrial adenosine triphosphatase from yeast, Saccharomyces cerevisiae. Purification, subunit structure and kinetics. 13 2

Adenosine triphosphate (ATP) hydrolysis catalyzed by the plasma membrane (Na+,K+)ATPase isolated from several sources was inhibited by Mg+, provided that K+ and ATP were also present. Phosphorylation of the adenosine triphosphatase (ATPase) by ATP and by inorganic phosphate was also inhibited, as was p-nitrophenyl phosphatase activity. (Ethylenedinitrilo)tetraacetic acid (EDTA) and catecholamines protected from and reversed the inhibition of ATP hydrolysis by Mg2+, K+ and ATP. EDTA was protected by chelation of Mg2+ but catecholamines acted by some other mechanism. The specificities of various nucleotides as inhibitors (in conjunction with Mg2+ and K+) and as substrates for the (Na+, K+) ATPase were strikingly different. ATP, ADP, beta,gamma-CH2-ATP and alpha,beta-CH2-ADP were active as inhibitors, whereas inosine, cytidine, uridine, and guanosine triphosphates (ITP, CTP, UTP, and GTP) and adenosine monophosphate (AMP) were not. On the other hand, ATP and CTP were substrates and beta,gamma-NH-ATP was a competitive inhibitor of ATP hydrolysis, but not an inhibitor in conjunction with Mg2+ and K+. The Ca2+-ATPase from sarcoplasmic reticulum and F1, the Mg2+-ATPase from the inner mitochondrial membrane, were also inhibited by Mg2+. Catecholamines reversed inhibition of the Ca2+-ATPase, but not that of F1.
...
PMID:Reversible inhibition of (Na+, K+) ATPase by Mg2+, adenosine triphosphate, and K+. 13 42

A partially purified soluble ATPase (ATP phosphohydrolase, EC 3.6.1.3) from pea cotyledon mitochondria was characterized. Inhibition patterns with azide, NaF, and cold, and a stimulation by 2,4-dinitrophenol were typical of F1-ATPases from mammalian mitochondria. The enzyme hydrolysed GTP, ITP, and ATP, but not CTP, UTP, ADP, or IDP. ATPase and ITPase activities were strongly inhibited by ADP and to a lesser extent by IDP. Distinctive properties of the pea mitochondrial enzyme were activation by high concentrations of CaCl2 and stimulation by NaCl.
...
PMID:Partial characterization of a soluble ATPase from pea cotyledon mitochondria. 14 76

Ca2+-ATPase of skeletal muscle sarcolemma has been isolated and purified. It is prepared from salt extract of sarcolemma by ammonium sulfate fractionation and further purified by gel chromatography on Sepharose 4B. The purity of preparations was evaluated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. It has been shown that Ca2+-ATPase possesses the same mobility as skeletal muscle myosin under gel chromatography on Sepharose 4B and the same mobility as myosin heavy chains in sodium dodecyl sulfate--polyacrylamide gel electrophoresis. Membrane protein binds to rabbit skeletal muscle actin, and this complex dissociates by ATP. Interaction with actin does not change Ca2+- or Mg2+-stimulated ATPase activity. Enzyme has only one pH optimum at 7,0-7,6. Membrane protein is highly specified to calcium--ATPase activity in the presence of Mn2+ is 10% and in the presence of Sr2+, Mg2+ or Co2+ are 3-5% of the activity in the presence of Ca2+. Other nucleoside triphosphate (UTP and ITP) are hydrolyzed at lower rates than is ATP.
...
PMID:[Purification and some properties of skeletal muscle sarcolemma Ca2+-ATPase]. 14 19

Some properties of membrane ATPase activity in Veillonella alcalescens were examined. Mg2+ is required for the activity of the enzyme, and Ca2+ also activates the enzyme to some degree. Of the nucleotide triphosphates, GTP and ITP were hydrolyzed to a lesser extent than ATP. The apparent Km for ATP hydrolysis was 0.25 to 0.63 mM. ADP inhibited the enzyme and the kinetic data of its inhibition showed that the presence of ADP resulted in positive cooperativity. The enzyme activity was strongly inhibited by DCCD, azide, fusidic acid and the antibody to purified soluble ATPase from the thermophilic bacterium PS3. Oligomycin, dinitrophenol, and ouabain showed no significant effect.
...
PMID:Properties of membrane adenosine triphosphatase of the obligately anaerobic bacterium Veillonella alcalescens. 14 19

The effect of organic solvents on the beef heart mitochondrial ATP-base-catalyzed ATP and ITP hydrolysis was examined. It was observed that numerous organic solvents stimulated ATP hydrolysis while ITP hydrolysis was inhibited. Methanol at 20% (v/v) was found to stimulate ATP hydrolysis by over 300%, while at the same methanol concentration ITP hydrolysis was inhibited approximately 50%. In the presence of 20% methanol, ATP hydrolysis exhibited linear plots of 1/[ATP] vs. 1/v, while in the absence of methanol negative cooperativity was observed. These data can be interpreted to imply that the catalytic and regulatory sites of the mitochondrial ATPase are being dissociated 20% methanol. The effect of methanol on the hydrolysis of ATP and ITP was examined as a function of pH. It was found that, at high pH in totally aqueous solutions, the hydrolysis of ATP and ITP was inhibited, while the presence of 20% methanol either caused the hydrolytic rate to peak and remain constant above pH 8 (with ATP as substrate) or caused the rate of hydrolysis to continue to increase above pH 8 (when ITP was the substrate). These data are interpreted to indicate that an acidic group in the active site may be ionizing, limiting the ATPase-catalyzed hydrolytic rate, and, with 20% methanol, this ionization was inhibited.
...
PMID:Effect of organic solvents on the beef heart mitochondrial adenosine triphosphatase. 15 24

The effect of RNA secondary structure on rho-independent and rho-dependent termination of transcription of T3 DNA by Escherichia coli RNA polymerase has been studied by incorporating, into nascent transcripts, base analogs that lead to altered base-pairing properties. A guanine --> hypoxanthine substitution, with attendant weakening of secondary structure, abolished the rho-independent termination at 20% of the genome; in contrast, replacement of cytosine with 5-bromocytosine, which forms stronger pairs with guanine, enhanced termination at this site. rho-Independent termination was not altered by replacing uracil with 5-bromouracil. There are two major rho-dependent termination sites on the T3 DNA-at 8 and 15%. The termination activity of rho in this system also depended on RNA secondary structure. The incorporation of 5-bromouracil instead of uracil into RNA did not alter the site specificity of rho action but rho was rendered inactive when cytosine was replaced by 5-bromocytosine. In contrast, replacement of GTP with ITP in the reaction increased rho-dependent inhibition of RNA synthesis, caused production of heterogeneous-sized transcripts, and stimulated rho-mediated ATP hydrolysis. The rho-associated ATPase activity, in the presence of isolated T3 RNA, was also stimulated by inosine substitution. Furthermore, the temperature-sensitive rho isolated from rho 15 mutant of E. coli, which does not terminate transcription in the presence of the common rNTPs, was active when GTP was replaced with ITP. These results suggest that strongly paired G.C-rich regions in RNA stem-loop structures or RNA.DNA hybrids are essential for rho-independent termination, whereas rho-dependent termination requires weakly paired cytosine residues for its action.
...
PMID:Termination of transcription by Escherichia coli RNA polymerase: influence of secondary structure of RNA transcripts on rho-independent and rho-dependent termination. 15 60

1. Isolation of ATPase from rat liver submitochondrial particles by chloroform treatment requires the presence of ATP or ADP during enzyme solubilization. In the absence of adenine nucleotides the enzyme activity is very low although all protein components of F1-ATPase are released. The low concentrations of ATP or ADP required (5 microM) indicate that the high affinity nucleotide-binding sites are involved in enzyme stabilization. Other nucleotides tested (ITP, GTP, UTP, CTP) were found to be less effective. 2. Polyacrylamide gel electrophoresis and immunodiffusion in agar plates revealed that in the absence of adenine nucleotides a fraction of F1-ATPase released by chloroform treatment is split into fragments. The part of the dissociated enzyme molecule has a molecular weight identical with that of a beta-subunit of F1-ATPase. 3. Dissociation of the F1-ATPase molecule could also be prevented by aurovertin. 4. Crude F1-ATPase solubilized by chloroform treatment can be further purified by Sepharose 6B gel filtration. Specific ATPase activity of the purified enzyme was 90 mumol Pi/min per mg protein and the enzyme was composed of five protein subunits (alpha, beta, gamma, delta, epsilon) with molecular weights 58 000, 55 000, 28 000, 13 000 and 8000, respectively. 5. Chloroform-released F1-ATPase from rat liver mitochondria displayed immunochemical cross-reactivity with that isolated from beef heart mitochondria.
...
PMID:Stabilization of rat liver mitochondrial F1-adenosine triphosphatase during chloroform-induced solubilization. 15 60

The rate of phosphorylation of the Ca2+-dependent ATPase of sarcoplasmic reticulum vesicles by ITP and ATP was studied using a millisecond mixing and quenching device. The rate of phosphorylation was slower when the vesicles were preincubated in a Ca2+-free medium than when preincubated with Ca2+, regardless of the substrate used and of the pH of the medium. When the vesicles were preincubated with Ca2+ at pH 7.4 an overshoot of phosphorylation was observed in the presence of ITP. The overshoot was abolished when the pH of the medium was decreased to 6.0 or when the vesicles were preincubated in a Ca2+-free medium. Using vesicles preincubated with Ca2+ the apparent Km for ITP found was 2.5 mM at pH 6.0 and 1.0 mM at pH 7.4. The Vmax observed (77 mumol g-1 s-1) did not change with the pH of the medium. Both at pH 6.0 and 7.4 the apparent Km for ATP was 3 microM when preincubated in a Ca2+-free medium. At pH 6.0 the Vmax for ATP varied from 96 to 33 mumol g-1 s-1 depending on whether the vesicles were preincubated in the presence or absence of Ca2+. At pH 7.4 the Vmax for ATP was 90 mumol g-1 s-1 in both conditions. The rate of phosphorylation of the vesicles was dependent on the relative Ca2+ and Mg2+ concentrations of the reaction medium regardless of the substrate used.
...
PMID:Substrate regulation of the sarcoplasmic reticulum ATPase. Transient kinetic studies. 15 93

The study deals with the interrelationship of the phosphate-transferring activities of the calcium-transporting sarcoplasmic reticulum membrane vesicles: the phosphate exchange between nucleoside triphosphate (NTP) and nucleoside diphosphate (NDP) (NTP-NDP exchange), the calcium-dependent NTase, and the phosphorylation of NDP by inorganic phosphate in the presence of NTP (NTP-Pi exchange). Different nucleotides were used as phosphate donors and acceptors. It is demonstrated for the phosphate transfer from ITP to GDP that the NTP-NDP exchange exhibits ping-pong kinetics with Mg-ITP and unliganded GDP as substrates. The apparent affinities of the enzyme for the nucleoside diphosphate and triphosphate species are deduced according to this mechanism. The enzyme's affinity for the nucleoside triphosphates and diphosphates depends on its functional state being considerably lower under conditions of NTP-NDP exchange than during NTP splitting or NTP synthesis. ATP and GTP are split with the same low rates when calcium-activated NTPase is inhibited by high internal calcium concentrations after calcium transport has reached steady state. The rates of the NTP-NDP exchange reactions, however, differ by a factor of about 10 being approximately equal to 3 mumol . mg-1 . min-1 for ATP-ADP and only approximately equal to 0.3 mumol . mg-1 . min-1 (22 degrees C) for GTP-GDP. When the sarcoplasmic reticulum vesicles are made calcium-permeable, the calcium transport ATPase is turned on and the rates of GTP and ATP splitting increase about tenfold. Yet, while the rate of ATP-ADP exchange is little reduced, the rate of GTP-GDP exchange drops by approximately 50%. The persisting exchange activity of calcium-permeable vesicles demonstrates that high internal calcium concentrations are not required for the transfer of the protein-bound phosphoryl group to NDP during NTP-NDP exchange.
...
PMID:Comparison between ATP-supported and GTP-supported phosphate turnover of the calcium-transporting sarcoplasmic reticulum membranes. 16 Mar 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---