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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Soluble ATPase (adenosine triphosphatase) activity is released when rat liver submitochondrial particles are shaken with chloroform, provided that ATP or glycerol is present in the suspending medium. The extraction is very rapid and appears to be complete. 2. The ATPase of the chloroform extract is about 50% pure and can be readily purified to a specific activity of 60-70mumol/min per mg of protein by (NH(4))(2)SO(4) fractionation and column chromatography on Sephadex G-200. 3. The particulate and soluble ATPases have many similar properties, including their K(m) values for ATP, activation by various metal ions, hydrolytic activity with other nucleotides and stimulation by bicarbonate ions. 4. Unlike the particulate enzyme, the soluble enzyme is cold-labile and insensitive to oligomycin. 5. The molecular weight indicated by the mobility of the soluble ATPase on Sepharose 6B is 360000. 6. The soluble ATPase combines very readily with liver submitochondrial particles depleted of ATPase by salt extraction, and oligomycin-sensitivity is restored. Very little recombination of the enzyme occurs with chloroform-extracted particles. 7. The soluble enzyme contains orcinol-reactive material, suggesting that it may be a glycoprotein. The carbohydrate content was estimated to be 1-2% by weight. 8. It is concluded that the liver ATPase obtained by the chloroform extraction method of Beechey, Hubbard, Linnett, Mitchell & Munn [(1975) Biochem. J.148, 533-537] is similar to other preparations described previously and that this method is superior in simplicity and speed.
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PMID:Purification and properties of the adenosine triphosphatase released from the liver mitochondrial membrane by chloroform. 15 21

1. A cold-stable oligomycin-sensitive F0F1 ATPase complex from chromatophores of Rhodospirillum rubrum FR 1 was solubilized by Triton X-100 and purified by gel filtration. 2. The F0F1 complex is resolved by sodium dodecyl sulfate electrophoresis into 14 polypeptides with approximate molecular weights in the range of 58000--6800; five of these polypeptides are derived from the F1 moiety of the complex which carries the catalytic centers of the enzyme. 3. The purified F0F1 complex is homogeneous according to analytical ultracentrifugation and isoelectric focusing. 4. The molecular weight as determined by gel filtration is about 480 000 +/- 30 000. S020,w is 1.45 +/- 0.1 S and the pI is 5.4. 5. The amino acid composition of the F0F1 complex is compared with the data obtained for the F1 moiety of the enzyme. 6. Quantitative data on the sensitivity to N,N'-dicyclohexyl-carbodiimide as well as kinetic parameters, regarding substrate specificity and dependence of ATPase activity on divalent cations, are reported.
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PMID:Properties of the F0F1 ATPase complex from Rhodospirillum rubrum chromatophores, solubilized by Triton X-100. 15 77

Trimmed strips of sternomandibularis muscles taken from freshly-slaughtered cattle were placed in an isotonic myograph and cooled to 1 degree C. Spontaneous activity due to neuromuscular irritability was minimized by keeping muscle surfaces moist and anaerobic and was monitored by electromyography. Muscle strips were removed and frozen for histochemical analysis after they had completed their initial phase of cold-induced shortening (several hours). Control strips maintained for an equal time at 24 degrees C rarely depleted the stainable glycogen in any of their muscle fibres so as to become PAS-negative. In chilled muscle strips, however, glycogenolysis was activated in some muscle fibres and they became PAS-negative. In serial sections, most of the PAS-negative fibres exhibited strong ATPase and weak succinate dehydrogenase activity. Fibres with weak ATPase and strong succinate dehydrogenase activity rarely became PAS-negative. These results are in agreement with biochemical reports of a cold-induced (less than 5 degrees C) activation of glycolysis in skeletal muscle post mortem. Investigations on untrimmed lengths of excised sternomandibularis muscle indicated that longitudinal muscle damage caused in cutting muscle strips for the myograph and/or their more rapid rate of initial cooling had facilitated the depletion of stainable glycogen.
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PMID:Low temperature activation of post mortem glycogenolysis in bovine skeletal muscle fibres. 15 72

Tightly bound magnesium was found in soluble, purified ATPase (F1) from beef heart mitochondria in the amount of 1 mol/mol of F1. Iron, zinc, cobalt, manganese, calcium, sodium, copper, and potassium were not tightly bound at stoichiometric levels. Removal of magnesium by chelating agents caused loss of ATPase activity. Removal of tightly bound nucleotide by gel filtration in 50% glycerol- or 60 mM K2SO4-containing buffers did not remove magnesium. Cold dissociation did release magnesium when complete denaturation was accomplished. The results suggest that magnesium is an integral part of F1, that it is required for activity, and that magnesium and nucleotides are tightly bound at separate sites. The idea that the tightly bound nucleotides are not complexed with cations suggests certain structural requirements at their binding sites which might account for the unusual properties of the sites.
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PMID:Tightly bound magnesium in mitochondrial adenosine triphosphatase from beef heart. 15 99

Undecalcified bone and cartilage tissue blocks were fixed for 3 h in cold formol-calcium, rapidly dehydrated with a graded series of cold ethanol, and embedded in glycol methacrylate. 2 mum sections were produced with a Sorvall JB-4 microtome using glass knives. The quality of the sections were usually excellent except for hard bone from old subjects where the bone sometimes shattered while sectioning. This method is short, relatively uninvolved and eliminates en bloc decalcification. Moreover, the method is gentle enough to allow the histochemical demonstration of alkaline and acid phosphatase by the azo dye methods, and acid phosphatase, 5'-nucleotidase and ATPase by the lead precipitation methods.
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PMID:Enzyme histochemistry of undecalcified bone and cartilage embedded in glycol methacrylate. 17 7

The Na+/K+ ATPase activity of membrane fractions prepared from brown adipose tissue of cold-acclimated rats could be stimulated by addition of any one of the following: norepinephrine, isoproterenol, cyclic AMP or phenylephrine. These results are consistent with the proposal that in the intact brown adipocyte, the norepinephrine-induced stimulation of the Na+/K+ membrane pump is associated with alpha- as well as beta-adrenergic pathways and is, in part, mediated via cyclic AMP.
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PMID:The effect of adrenergic agonists and cyclic AMP on the Na+/K+ ATPase activity of brown adipose tissue. 18 33

The activity of Na,K-ATPase of the rat brain and kidney is 1.5--2-fold as increased during intermittent and prolonged (16 weeks) adaptation to cold, without changes in the enzyme affinity to ATP. It is suggested that adaptive increase in the power of the Na pump, triidothyronine-dependent in the kidneys and triiodothyronine-independent in the brain, ensures elevation in thermal production to body cooling.
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PMID:[Brain and kidney, Na, K-ATPase activation in the rat in adaptation to cold]. 21 52

1. It is known that extracellular Na+ ions, in low concentrations, inhibit Na+-ATPase activity in resealed red cell ghosts and that this inhibition is reversed by high concentrations of extracellular Na+. We have attempted to elucidate these actions of extracellular Na+ by investigating the dependence on Na+ concentration of (a) ATP-ADP exchange and Na+-ATPase activity both in native and in N-ethylmaleimide (NEM)-treated (Na+ + K+)-ATPase from pig kidney, and (b) the rate of hydrolysis of the phosphorylated kidney enzyme in the absence of K+ ions. 2. With the native enzyme, ATP-ADP exchange and Na+-ATPase activity showed similar responses to changes in Na+ concentration: a steep but S-shaped rise between 0 and 2.5 mM, a slight fall (exchange) or a plateau (ATPase) between 2.5 and 10 mM, and a roughly linear rise between 10 and 150 mM. With NEM-treated enzyme, the ATP-ADP exchange, which was greatly accelerated, showed no sign either of inhibition at intermediate Na+ concentrations or of the reversal of that inhibition at higher concentrations. The exchange rate increased with Na+ concentration in a smooth curve and was half-maximal at about 7 mM. 3. The effects, on ATP-ADP exchange, of changing the concentrations of ATP, ADP and Mg have also been investigated. With both native and NEM-treated enzyme, the interactions of ATP, ADP and Mg are complicated; they show that, for the reaction leading to ATP formation, either free ADP rather than MgADP is the substrate, or Mg2+ ions are inhibitory (or both). 4. Since NEM, in the conditions in which we have used it, is believed to act by inhibiting the conversion of an ADP-sensitive form of the phosphoenzyme (E1P) to an ADP-insensitive form (E2P), the absence of Na+ inhibition of ATP-ADP exchange in NEM-treated enzyme, together with the parallel effects of Na+ ions on the ATP-ADP exchange activity and on the Na+-ATPase activity of native enzyme, suggests that the inhibitory effect of external Na+ occurs after the conversion of E1P into E2P. 5. To test whether this inhibitory effect of Na+ reflected inhibition of the hydrolysis of E2P, we measured the rate of loss of incorporated 32P when enzyme, newly phosphorylated by [gamma32P]ATP, was squirted into a large volume of ice-cold solution containing 1,2-cyclohexylenedinitrilotetraacetic aicd (CDTA), unlabelled ATP and 0, 5 or 150 mM-Na+. The rate of loss of radioactivity from the membranes was least at 5 mM-Na+, about twice as great at 150 mM-Na+, and about 5 times as great at 20 microM (final) Na+. 6. An unexpected feature of the results was that the pattern of stimulation of ATP-ADP exchange in intact cells. If Na+ ions are absent externally, a different could be fitted better on the assumption that activation by internal Na+ occurs at two sites with equal affinities, than on the assumptions that activation occurs at a single site or at three sites with equal affinities.
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PMID:Sodium ions, acting at high-affinity extracellular sites, inhibit sodium-ATPase activity of the sodium pump by slowing dephosphorylation. 22 96

Four DNA-dependent ATPases have been isolated from E. coli extracts. ATPases I and III, both sensitive to NEM, require denatured DNA but differ in their heat sensitivity, elution from DEAE-cellulose, and sedimentation coefficient. ATPases II and IV are both resistant to NEM. ATPase II requires partially denatured DNA, whereas ATPase IV can be stimulated by SS DNA. ATPase I is a DNA-unwinding enzyme; ATPase II may be involved in recombination.
Cold Spring Harb Symp Quant Biol 1979
PMID:DNA-dependent ATPases from Escherichia coli K12. 22 6

In summary, we postulate that DNA unwinding and ATP dephosphorylation are coupled in different ways, depending on whether the fibrous ATPase or one of the globular ATPases provides the catalytic agent. Unanswered is the question of whether there is stoichiometry of ATP utilization during the unwinding of a duplex, and unsolved is the role of the individual enzyme in the cell.
Cold Spring Harb Symp Quant Biol 1979
PMID:DNA helicases. 22 20


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