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  • 1
    Electronic Resource
    Electronic Resource
    Blaue Liste Institute (1999)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 29 (1999), S. 375-375 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.960290612
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Demonstration of β-N-acetyl-D-glucosaminidase and β-N-acetyl-D-hexosaminidase in Drosophila Kc-cells (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 17 (1991), S. 3-13 
    Details
    ISSN: 0739-4462
    Keywords: intra- and extracellular enzymes ; kinetic properties ; inhibition ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Kc-cells from Drosophila melanogaster, grown under serum-free conditions, produce two β-hexosaminidases and secrete these enzymes into the medium. The two enzymes were separated by DEAE-exchange chromatography. According to their substrate specificities one enzyme is a β-N-acetyl-D-glucosaminidase (E.C.3.2.1.30), the other one a β-N-acetyl-D-hexosaminidase (E.C.3.2.1.52). The β-N-acetyl-D-glucosaminidase is predominant in the medium, the β-N-acetyl-D-hexosaminidase within the cells. The Km values for the substrates pNP-GlcNAc, pNP-GalNAc, and (GlcNAc)2 are 0.8, 16.73, and 1.67 mM for the β-N-acetyl-D-glucosaminidase and 0.24, 0.44, and 0.2 mM for the β-N-acetyl-D-hexosaminidase. Both enzymes are inhibited by the products and the β-N-acetyl-D-glucosaminidase is also inhibited stereospecifically by the substrates pNP-GlcNAc and (GlcNAc)2. Both enzymes are inhibited in a partial competitive way by acetamidolactones, the Kis being as low as 0.1 μM.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940170103
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  • 3
    Electronic Resource
    Electronic Resource
    Physical properties of β-N-acetyl-D-glucosaminidase and β-N-acetyl-D-hexosaminidase from Drosophila Kc-cells (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 18 (1991), S. 45-53 
    Details
    ISSN: 0739-4462
    Keywords: molecular mass ; pH and temperature optima ; thermal stability ; influence of ionic strength ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Kc-cells from Drosophila produce two different β-D-hexosaminidases, a β-N-acetyl-D-glucosaminidase (E.C.3.2.1.30) and a β-N-acetyl-D-hexosaminidase (E.C.3.2.1.52), which are also secreted into the medium. The Mr of both enzymes is about 126,000 ± 9,700; the S-values are 8.37 ± 0.44. Both enzymes have about the same pH optima at 5.5 and the same thermal stability. The temperature optima are identical (50°C) for both enzymes if p-nitrophenyl-N-acetylglucosaminide is used as a substrate. However, when p-nitrophenyl-N-acetylgalactoseaminide is used as the substrate the β-N-acetyl-D-hexosaminidase has a temperature optimum about 10°C higher. With higher salt concentrations, the activity of the β-N-acetyl-D-glucosaminidase increases, whereas β-N-acetyl-D-hexosaminidase is inhibited. Both enzymes also differ in their sensitivity to urea, the β-N-acetyl-D-hexosaminidase being less sensitive than the β-N-acetyl-D-glucosaminidase.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940180105
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  • 4
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    Differential effects of elevated 〈scp〉 〈i〉p〈/i〉 CO 〈sub〉2〈/sub〉 〈/scp〉 and warming on marine phytoplankton stoichiometry (2022)
    Wiley
    In:  EPIC3Limnology and Oceanography, Wiley, 67(3), pp. 598-607, ISSN: 0024-3590
    Details
    Publication Date: 2022-09-15
    Description: Phytoplankton stand at the base of the marine food-web, and play a major role in global carbon cycling. Rising CO2 levels and temperatures are expected to enhance growth and alter carbon:nutrient stoichiometry of marine phytoplankton, with possible consequences for the functioning of marine food-webs and the oceanic carbon pump. To date, however, the consistency of phytoplankton stoichiometric responses remains unclear. We therefore performed a meta-analysis on data from experimental studies on stoichiometric responses of marine phytoplankton to elevated pCO2 and 3–5° warming under nutrient replete and limited conditions. Our results demonstrate that elevated pCO2 increased overall phytoplankton C:N (by 4%) and C:P (by 9%) molar ratios under nutrient replete conditions, as well as phytoplankton growth rates (by 6%). Nutrient limitation amplified the CO2 effect on C:N and C:P ratios, with increases to 27% and 17%, respectively. In contrast to elevated pCO2, warming did not consistently alter phytoplankton elemental composition. This could be attributed to species- and study-specific increases and decreases in stoichiometry in response to warming. While our observed moderate CO2-driven changes in stoichiometry are not likely to drive marked changes in food web functioning, they are in the same order of magnitude as current and projected estimations of oceanic carbon export. Therefore, our results may indicate a stoichiometric compensation mechanism for reduced oceanic carbon export due to declining primary production in the near future.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
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