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  • Animals  (2)
  • Chemistry  (2)
  • Humans
  • Velocity depth profile
  • 2000-2004  (3)
  • 1995-1999  (2)
  • 1980-1984
  • 1950-1954
  • 2004  (3)
  • 1995  (2)
  • 1
    ISSN: 0006-3592
    Schlagwort(e): hydrolysis ; esterification ; Humicola lanuginosa ; Rhizomucor miehei ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Humicola lanuginosa lipase (HIL) and Rhizomucor miehei lipase (RrnL), isolated from commercial preparations of Lipolase and Lipozyme, respectively, were solubilized in AOT-stabilized water-in-oil (w/o) microemulsions in n-heptane and aspects of their hydrolysis and condensation activity examined. The temperature dependence of HIL hydrolysis activity in unbuffered R = 10 microemulsions matched very closely that for tributyrin hydrolysis by Lipolase in an aqueous emulsion assay. Apparent activation energies were measured as 13 ± 2 and 15 ± 2 kJ mol / respectively. Condensation activity, however, was essentially independent of temperature over the range 5° to 37°C. The stability of HIL over a 30-day period was very good at all pH levels (6.1, 7.2, 9.3) and R values studied (5, 7.5, 10, 20), except when high pHs and low R values were combined. The excellent stability was reflected by the linearity of the productivity profiles which facilitate system optimization. The temperature dependence of RmL hydrolysis activity toward pNPC4 showed a maximum at 40°C and an apparent Eact = 20 ± 2 kJ mol-1 was calculated based on the linear region of the profile (5° to 40°C). RmL esterification activity showed only a slight dependence on temperature over the studied range (0° to 40°C) and an apparent Eact = 5 ± 1 kJ mol-1 was measured for octyl decanoate synthesis. Both RmL and HIL, therefore, have potential for application in low temperature biotransformations in microemulsion-based media. The stability of RmL over a 30-day period was good in R = 7.5 and R = 10 microemulsions containing pH 6.1 buffer, and this was reflected in the linearity of their respective productivity profiles. RmL stability was markedly poorer at more alkaline pH, however, and proved to be sensitive to relatively small changes in the R value. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 0006-3592
    Schlagwort(e): hydrolysis ; esterification ; Humicola lanuginosa ; Rhizomucor miehei ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Lipolase and Lipozyme are produced in large quantities (as a result of genetic engineering and overexpression) for the detergents market and provide a cheap source of highly active biocatalysts. Humicola lanuginosa lipase (HIL) and Rhizomucor miehei lipase (RmL) have been isolated in partially purified form from commercial preparations of Lipolase and Lipozyme, respectively. These lipases were solubilized in Aerosol-OT (AOT)-stabilized water-in-oil (w/o) microemulsions in n-heptane. HIL and RmL activity in these microemulsions was assayed by spectrophotometric measurement of the initial rate of p-nitophenyl butyrate hydrolysis, and by chromatographic determination of the initial rate of octyl decanoate synthesis from 1-octanol and decanoic acid. The hydrolytic activity of HIL in microemulsions measured as a function of buffer pH prior to dispersal, followed a sigmoidal profile with the highest activities observed at alkaline pHs. This broadly matches the pH-activity profile for tributyrin hydrolysis by Lipolase in an aqueous emulsion assay. The hydrolytic activity of RmL in the same microemulsions, measured as a function of pH, gave a bell-shaped profile with a maximum activity at pH 7.5. Again, the observed pH-activity profile was similar to that reported for a purified RmL in a tributyrin-based aqueous emulsion assay. In contrast, the esterification activity exhibited by both HIL and RmL in AOT microemulsions over the available range pH 6.1 to 10.4, decreases as the pH increases, most likely reflecting the effect of substrate ionization. The dependence of the hydrolytic and condensation activity of HIL on R, the mole ratio of water to surfactant, were similar with both profiles exhibiting a maximum at R = 5. The hydrolytic and esterification activities of RmL followed similar R-dependent profiles, but the profiles in this case exhibited a maximum at R = 10. The water activities at these R values were directly measured as 0.78 and 0.9, respectively. Measured water activities were unperturbed by the presence of lipase at the concentrations used in these studies. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    facet.materialart.
    Unbekannt
    In:  Tectonophysics, Houston, Akademie-Verlag, vol. 381, no. 1-4, pp. 211-233, pp. L08310, (ISSN: 1340-4202)
    Publikationsdatum: 2004
    Schlagwort(e): Mohorovicic disc. ; depth ; Velocity depth profile ; Deep seismic sounding (espec. cont. crust) ; EUROPROBE (Geol. and Geophys. in eastern Europe)
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2004-11-30
    Beschreibung: The widespread extinctions of large mammals at the end of the Pleistocene epoch have often been attributed to the depredations of humans; here we present genetic evidence that questions this assumption. We used ancient DNA and Bayesian techniques to reconstruct a detailed genetic history of bison throughout the late Pleistocene and Holocene epochs. Our analyses depict a large diverse population living throughout Beringia until around 37,000 years before the present, when the population's genetic diversity began to decline dramatically. The timing of this decline correlates with environmental changes associated with the onset of the last glacial cycle, whereas archaeological evidence does not support the presence of large populations of humans in Eastern Beringia until more than 15,000 years later.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shapiro, Beth -- Drummond, Alexei J -- Rambaut, Andrew -- Wilson, Michael C -- Matheus, Paul E -- Sher, Andrei V -- Pybus, Oliver G -- Gilbert, M Thomas P -- Barnes, Ian -- Binladen, Jonas -- Willerslev, Eske -- Hansen, Anders J -- Baryshnikov, Gennady F -- Burns, James A -- Davydov, Sergei -- Driver, Jonathan C -- Froese, Duane G -- Harington, C Richard -- Keddie, Grant -- Kosintsev, Pavel -- Kunz, Michael L -- Martin, Larry D -- Stephenson, Robert O -- Storer, John -- Tedford, Richard -- Zimov, Sergei -- Cooper, Alan -- New York, N.Y. -- Science. 2004 Nov 26;306(5701):1561-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Henry Wellcome Ancient Biomolecules Centre, Oxford University, South Parks Road, Oxford OX13PS, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15567864" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Alaska ; Animals ; Bayes Theorem ; *Bison/classification/genetics ; Canada ; China ; *Climate ; DNA, Mitochondrial/genetics ; Environment ; *Fossils ; Genetic Variation ; Genetics, Population ; Human Activities ; Humans ; North America ; Phylogeny ; Population Dynamics ; Sequence Analysis, DNA ; Time
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2004-08-25
    Beschreibung: Intracellular acidification of skeletal muscles is commonly thought to contribute to muscle fatigue. However, intracellular acidosis also acts to preserve muscle excitability when muscles become depolarized, which occurs with working muscles. Here, we show that this process may be mediated by decreased chloride permeability, which enables action potentials to still be propagated along the internal network of tubules in a muscle fiber (the T system) despite muscle depolarization. These results implicate chloride ion channels in muscle function and emphasize that intracellular acidosis of muscle has protective effects during muscle fatigue.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pedersen, Thomas H -- Nielsen, Ole B -- Lamb, Graham D -- Stephenson, D George -- New York, N.Y. -- Science. 2004 Aug 20;305(5687):1144-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Aarhus, DK-8000, Denmark.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15326352" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Action Potentials ; Animals ; Calcium/metabolism ; Chloride Channels/*metabolism ; Chlorides/metabolism ; Electric Stimulation ; Hydrogen-Ion Concentration ; In Vitro Techniques ; Lactic Acid/metabolism ; Membrane Potentials ; Muscle Contraction ; *Muscle Fatigue ; Muscle Fibers, Skeletal/metabolism/*physiology ; Muscle, Skeletal/metabolism/*physiology ; Permeability ; Potassium/metabolism ; Rats ; Sarcoplasmic Reticulum/metabolism
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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