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

The adenosinetriphosphatase (ATPase) (EC 3.6.1.3) activity in Azotobacter vinelandii concentrates in the membranous R3 fraction that is directly associated with Azotobacter electron transport function. Sonically disrupted Azotobacter cells were examined for distribution of ATPase activity and the highest specific activity (and activity units) was consistently found in the particulate R3 membranous fraction which sediments on ultracentrifugation at 144 000 X g for 2 h. When the sonication time interval was increased, the membrane-bound ATPase activity could neither be solubilized nor released into the supernatant fraction. Optimal ATPase activty occurred at pH 8.0; Mg2+ ion when added to the assay was stimulatory. Maximal activity always occurred when the Mg2+:ATP stoichiometry was 1:1 on a molar ratio at the 5 mM concentration level. Sodium and potassium ions had no stimulatory effect. The reaction kinetics were linear for the time intervals studied (0-60 min). The membrane-bound ATPase in the R3 fraction was stimulated 12-fold by treatment wiTH TRypsin, and fractionation studies showed that trypsin treatment did not solubilize ATPase activity off the membranous R3 electron transport fraction. The ATPase was not cold labile and the temperature during the preparation of the R3 fraction had no effect on activity; overnight refrigeration at 4 degrees C, however, resulted in a 25% loss of activity as compared with a 14% loss when the R3 fraction was stored overnight at 25 degrees C. A marked inactivation (although variable, usually about 60%) did occur by overnight freezing (-20 degrees C), and subsequent sonication failed to restore ATPase activity. This indicates that membrane reaggregation (by freezing) was not responsible for ATPase inactivation. The addition of azide, ouabain, 2,4-dinitrophenol, or oligomycin to the assay system resulted in neither inhibition nor stimulation of the ATPase activity. The property of trypsin activation and that ATPase activity is highest in the R3 electron transport fraction suggests that its probable functional role is in coupling of electron transport to oxidative phosphorylation.
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PMID:Characterization studies on the membrane-bound adenosine triphosphatase (ATPase) of Azotobacter vinelandii. 0 Jan 41

We have compared the adenosine triphosphatase (ATPase) activity of mitochondria prepared from wild-type Neurospora crassa and from poky, a maternally inherited mutant known to possess defective mitochondrial ribosomes and reduced amounts of cytochromes aa3 and b. poky contains two distinct forms of mitochondrial ATPase. The first is normal in its Km for ATP, specificity for nucleotides and divalent cations, pH optimum, cold stability, and sensitivity to inhibitors (oligomycin, N,N-dicyclohexyl carbodiimide, and adenylyl imidodiphosphate). The fact that membrane-bound, cold-stable, oligomycin-sensitive ATPase activity is present in poky (with an activity of 1.93 +/- 0.03 mumol/min-mg of protein compared with 1.33 +/- 0.07 mumol/min-mg of protein in the wild-type strain) and also in chloramphenicol-grown wild-type cells suggests that products of mitochondrial protein synthesis play only a limited role in the attachment of the mitochondrial ATPase to the membrane in Neurospora. poky also contains a second form of mitochondrial ATPase, which has an activity of 1.5 +/- 0.2 mumol/min-mg of protein, is oligomycin sensitive but cold labile, and presumably is attached less firmly to the mitochondrial membrane. The two forms, added together, represent a substantial overproduction of mitochondrial ATPase by poky.
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PMID:Mitochondrial adenosine triphosphatase of wild-type and poky Neurospora crassa. 2 38

The histochemical activities of succinic dehydrogenase (SDH) and Ca++-activated ATPase (pHs 7.4 and 9.4) were studied in the larval tail musculature of Rana japonica, Rana catesbeiana and Rana ornativentris. The ATPase reaction product was detected by both light and electron microscopy. 'Red' and 'white' muscle fibres, as distinguished by SDH, showed high and low Ca++-ATPase reaction, respectively, at pHs 7.4, 9.4 and following preincubation in cold K2-EDTA solution. The ultrastructural investigation of Ca++-ATPase reaction at pH 7.4 by the Ca++-citrophosphate technique demonstrated electron-dense reaction product in association with A, I and 'Z' bands, intermyofibrillar (SR) compartment and the mitochondrial inner chamber. However, Pb++ precipitation technique demonstrated Mg++-activated myosin ATPase activity at pH 9.2 ultrastructurally. The present histochemical data suggest that the anuran larval tail 'red' muscle fibres are possible 'slow,' and emphasize a possible lack of correlation between the speed of contraction with their ATPase activity. Moreover, 'red' muscle fibres of the anuran tai- musculature are not equivalent to 'Type I' fibres of higher chordates.
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PMID:Light and electron microscopic study of adenosine triphosphatase activity of anuran tadpole musculature. 2 41

Mammalian and avian muscles were examined histochemically and biochemically to determine the relative contribution of membrane bound (mitochondrial and sarcotubular) ATPases under the same conditions employed for myofibrillar ATPase. For histochemically investigated Ca+(+)-ATPase activity following incubation at pH 9.4 according to the calcium-citro-phosphate technique, avian muscle displayed distinct mitochondrial localization in both dark and light staining fibres. However, mitochondrial localization did not occur in mammalian muscle fibres. Pretreatment of unfixed frozen sections with ouabain, cyanide and acetone did not prevent the reticular distribution in avian muscle fibres. The present study demonstrates that "myofibrillar" localization is achieved by the Ca+(+)-precipitation technique: provided frozen sections are pretreated with cold acetone, fixed in a fixative containing oligomycin or azide and then incubated in a medium containing glycine-NaO H as buffer. Mitochondria prepared by successive mechanical homogenization or by Nagarse treatment plus 2 min homogenization develop different ATPase activities at pH 9.4 7.4 6.0 and 4.35 as well as stimulation by 70 mM Ca++ at these pHs compared to those ATPase activities in the homogenate of mixed hamster hind leg muscles. Glycerol-3-phosphate dehydrogenase and creatine kinase (both located at the outer surface of the inner mitochondrial membrane) and succinate dehydrogenase and glutamate dehydrogenase (localized at the inner mitochondrial membrane and in the matrix resp.) also show different activities in both mitochondria preparations indicating different membrane properties of both mitochondria. Evidence is obtained that using the calcium-citro-phosphate technique at pH 9.4 oligomycin-sensitive and -insensitive ATPases are activated by Ca++ in both mitochondria preparations. Since in muscle homogenate less than 10% of Ca+(+)-stimulated ATPase activity is oligomycin-sensitive, mitochondrial ATPase exhibit only a small portion of total ATPase from mixed hamster hind leg muscles.
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PMID:Histochemical and biochemical investigations of adenosine triphosphatase in vertebrate mixed muscles. 4 33

The effects of fixation with various concentrations of glutaraldehyde or formaldehyde, acetone or ethanol, and freeze-drying on 5 phosphatases of Eimeria tenella and chick kidney cell cultures were demonstrated in situ. Gultaraldehyde inactivated the phosphatases more than did the formaldehyde, but the effect of the combination of the 2 (Karnovsky's fixative) was greater than that of either glutaraldehyde or formaldehyde alone. The higher the concentration of aldehyde and the longer the duration of exposure, the greater the inactivation. The order of sensitivity to aldehyde fixation of the enzymes tested was glucose-6-phosphatase greater than thiamine pyrophosphatase greater than 5'-nucleotidase greater than adenosine triphosphatase greater than acid phosphatase. Cytologic detail was preserved more efficiently with glutaraldehyde than with formaldehyde. Optimal preservation of enzyme activity for cytochemistry was with 2% glutaraldehyde for 30 min or 2% formaldehyde for 1 hr for G-6-Pase, TPPase, and 5'-nucleotidase, and with 2% glutaraldehyde or 2% formaldehyde for 2 hr with ATPase and AcPase. Quenching with subsequent fixation in cold acetone or ethanol resulted in complete inactivation of G-6-Pase, TPPase, and 5'-nucleotidase; although cells fixed in this manner yielded large amounts of reaction product for ATPase and AcPase, the distribution was diffuse, and some of it appeared to be artifactual. Quenching with subsequent freeze-drying was unsatisfactory because nearly all of the cell layers rolled off the cover glasses.
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PMID:Effect of fixation on demonstration of phosphatases of Eimeria tenella grown in chick kidney cell cultures. 6 Dec 71

The effect of 24 and 48 hours' cold stress on the hamsters' adrenomedullary follicles and on the medullary ATPase activity was studied by light and electron microscopy. Only norepinephrine cells were depleted after this stress, and exocytosis seemed to be the mechanism involved in the release of catecholamine. Follicles containing these cells expanded and their lumina became narrow. A few other cellular and follicular changes also occurred and are described. ATPase activity was apparent in control organs along the endothelial linings, in neural elements and macrophages, and in approximately 40% of the linings of follicular lumina. Cold stress did not alter this pattern. These results have been compared with previous findings and the possible functions of the follicular lumina are discussed. It is concluded that they are unlikely sites for catecholamine storage or release.
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PMID:Ultrastructural and histochemical study of the adrenal medulla in normal and cold-stressed Syrian hamsters. 12 1

1. Prolonged treatment of coupling factor I (CF1) from spinach chloroplasts with trypsin free of chymotrypsin yielded an active ATPase. The isolated preparation showed only two polypeptide chains (mol wt 55,000 to 60,000) on acrylamide gels run in the presence of sodium dodecyl sulfate. The three smaller subunits of CF1 were not detectable. The preparation no longer served as a coupling factor for photophosphorylation in either EDTA- or silicotungstate-treated chloroplasts. 2. An antiserum prepared against coupling factor I from chloroplasts inhibited the ATPase activity of the trypsin-treated CF1. In contrast, antisera prepared against the two individual (denatured) subunits did not inhibit the ATPase activity when tested either alone or together, although each interacted with the trypsin-treated protein, forming precipitin lines in Ouchterlony plates. 3. The trypsin-treated enzyme was still cold-labile, showing that the three smaller subunits are not required for this property. However, the enzyme was no longer sensitive to the natural inhibitor protein which is one of its subunits (subunit epislon), but was still sensitive to inhibition by the flavonoid quercetin. 4. Two equivalents of 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole were sufficient to inhibit about 80% of the ATPase activity of the coupling factor, irrespective of whether it contained two of five subunits. The inhibition was completely reversed by dithiothreitol. 5. Triated 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole was prepared. Treatment of the coupling factor with this tritium-labeled inhibitor followed by electrophoresis on acrylamide gels revealed that most of the radioactivity was incorporated into the beta subunit of the enzyme (molecular weight 56,000).
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PMID:Partial resolution of the enzymes catalyzing photophosphorylation. XV. Approaches to the active site of coupling factor I. 12 75

Exposure of rats to an ambient temperature of 5 degrees C for 4 to 6 weeks led to a 30 to 80 percent increase in the rate of oxygen consumption and a 50 percent increase in the rate of ethanol oxidation by liver slices, a 50 percent increase in mitochondrial alpha-glycerophosphate oxidase activity of liver, and a 100 percent increase in Na++K+-activated adenosine-triphosphatase, activity. Ouabain, an inhibitor of the Na++K+-activated adenosine-triphosphatase, completely blocked the extra respiration and ethanol oxidation. Dinitrophenol, which increases oxygen consumption and ethanol oxidation by liver slices from normal rats, was ineffective with slices from cold-exposed animals. Ethanol disappearance rate in vivo was also increased by cold acclimation, even though liver alcohol dehydrogenase activity was reduced. It is suggested that increased hydrolysis of ATP by the sodium pump system is responsible for the increased oxygen consumption and ethanol metabolism in the livers of cold-acclimated animals.
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PMID:Ethanol metabolism and liver oxidative capacity in cold acclimation. 12 85

1. The bound nucleotides of the beef-heart mitochondrial ATPase (F1) are lost during cold inactivation followed by (NH4)2SO4 precipitation. The release of tightly bound ATP parallels the loss of ATPase activity during this process. 2. During cold inactivation, the sedimentation coefficient (s20, w) of the ATPase first declines from 12.1 S to 9 S, then to 3.5 S. (NH4)2SO4 precipitation of the 9-S component also leads to dissociation into subunits with s20, w of 3.5 S. 3. The 9-S component still contains the bound nucleotides, which are removed when it dissociated into smaller subunits. 4. Reactivation of cold-inactivated ATPase by incubation at 30 degrees C is increased by the presence of 25% glycerol. ATP, however, does not have any clearcut effect on the degree of reactivation in the presence of glycerol. 5. ADP is an inhibitor of the reactivation, probably because it exchanges during reactivation for bound ATP giving rise to an inactive 12-S component. 6. The exchange of tightly bound nucleotides with added adenine nucleotides is more extensive and faster with cold-inactivated ATPase than with the native enzyme. During reactivation up to 1.6 moles of ATP and 1.0 mole ADP can exchange per mole enzyme. 7. Incubation with GTP, CTP or inorganic pyrophosphate induces an increased activity of the ATPase, which, however, soon declines in the presence of ATP. It also disappears on precipitation of GTP-treated enzyme with (NH4)2SO4.
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PMID:Nucleotide-binding properties of native and cold-treated mitochondrial ATPase. 12 64

Membrane-bound ATPase (EC 3.6.1.3) of Escherichia coli K 12 is released in a soluble form by the mechanical treatments applied to the cells in order to break them. The purification of the soluble enzyme is described. The purified protein gives a single band in 7.5% polyacrylamide gel electrophoresis. The molecular weight is estimated to be 350 000. The enzyme is cold-labile, Mg-2+ dependent, insensitive to inhibition by N, N'-dicyclohexylcarbodiimide and specific for ATP and ADP. Membranes depleted of their ATPase activity by dilution in a buffer of low ionic strength and without Mg-2+ are able to incorporate the purified ATPase only in the presence of 2-6 mM Mg-2+. ATPase binds to particles formed by complementation between supernatant extracts of chl A and chl B mutants. There are three kinds of particles of different buoyant densities (1.10, 1.18 and 1.23); ATPase binds only to the 1.10 and 1.18 particles. The kinetics of incorporation have been studied. ATPase begins to be incorporated into the 1.10 particles after 10 min of incubation up to a maximum at 20 min: from 30 min, ATPase is incorporated only into 1.18 particles and the amount of incorporated ATPase increased in proportion with the peak of 1.18 particles. These kinetics have a hyperbolic pattern. In order to explain the mechanism of assembly involved in complementation, two hypotheses are proposed.
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PMID:Membrane reconstitution in chl-r mutants of Escherichia coli K 12. VII. Purification of the soluble ATPase of supernatant extracts and kinetics of incorporation into reconstituted particles. 12 90


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