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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics, mechanism, and time course analysis of lipase-catalyzed hydrolysis of high concentration olive oil in AOT-isooctane reversed micelles (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 206-211 
    Details
    ISSN: 0006-3592
    Keywords: reversed micelles ; lipase ; hydrolysis ; competitive product inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida rugosa lipase has been used to investigate the hydrolysis of high concentration olive oil in the AOT-isooctane reversed micellar system at Wo = 10, pH 7.1, and 37°C. Results from this work show the hydrolytic reaction obeys Michaelis-Menten kinetics up to the initial substrate concentration of 1.37M, with turnover number kcat and Michaelis constant KM of 67.1 μmol/min mg enzyme and 0.717M, respectively. A competitive inhibition by the main product, oleic acid, has been found with a dissociation constant KI for the complex EP* of 0.089M. The rate equation was further analyzed in the time course reaction and was found in agreement with the experimental results for lower substrate concentrations, up to 0.341M. Large deviation occurred at high substrate concentrations, which may be due to the effects of large consumption of water on kinetics, on the formation of glycerol, and on the deactivation of lipase in the hydrolysis reaction as well.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380213
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of solvent on enantioselective esterification of naproxen by lipase with trimethylsilyl methanol (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 64-68 
    Details
    ISSN: 0006-3592
    Keywords: enantioselectivity ; Naproxen ; esterification ; lipase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Improvement of stereoselective resolution of racemic Naproxen, 2-(6-methoxy-2-naphthyl)propionic acid, was attempted with esterifcation reaction by Candida cylindracea lipase. By carefully selecting the organic medium, a 72-time enhancement of yield of the desired S-ester was achieved. The optimal reaction temperature was approximately 53°C, and an alcohol concentration between 20 mM and 40 mM in an 80% (v/v) isooctane and 20% (v/v) toluene mixture was found. © 1994 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430109
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Surfactant enhancement of (S)-naproxen ester productivity from racemic naproxen by lipase in isooctane (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 51 (1996), S. 148-156 
    Details
    ISSN: 0006-3592
    Keywords: surfactant ; lipase ; Naproxen ; esterification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the enantioselective esterification of racemic Naproxen with trimethylsilyl methanol in isooctane by Candida cylindracea lipase, improvements in (S)-naproxen ester productivity and enzyme selectivity were demonstrated by adding bis(2-ethylhexyl) sodium sulfosuccinate (AOT) as the best surfactant. The effect of water content on the enhancement of enzyme activity was elucidated from the reduced adsorption of surfactant molecules on the lipase. A competitive inhibition by the alcohol and a noncompetitive inhibition by the surfactant to the enzyme were found from the kinetic analysis. By using a two-phase extraction, a complete separation of the surfactant from the organic solution was obtained. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Extraordinary enantiospecificity of lipase catalysis in organic media induced by purification and catalyst engineering (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 52 (1996), S. 296-300 
    Details
    ISSN: 0006-3592
    Keywords: enantioselective esterification ; lipase ; propionic acid ; catalysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A purified lipase preparation from Candida rugosa was compared to its crude counterpart in anhydrous and slightly hydrated hydrophobic organic solvents. The purified lipase preparation was less active than the crude enzyme in dry n-heptane, whereas the presence of small concentrations of added water dramatically activated the purified enzyme but not the crude enzyme. Thus, in the presence of as little as 0.25 μL/mL of added water in n-heptane, the purified enzyme is over 230-fold more active and 6-fold more enantioselective than the dry enzyme suspension in the esterification of racemic 2-(4-chlorophenoxy)propionic acid with n-butanol. The reactivity and selectivity of this biocatalyst, however, was affected by coalescence of the enzyme preparation suspended in the wet organic solvent. Engineering the biocatalyst environment by dissolving the purified lipase in aqueous buffer and then adding this solution to n-heptane resulted in a precipitated enzyme preparation with smaller particle sizes that did not coalesce severely. In the presence of 5 μL/mL of water added with the enzyme, this pretreatment resulted in an activation over the dry, purified enzyme preparation of over 1800-fold and nearly enantiospecific catalysis (E 〉 100). Hence, by simply modifying the way enzymes are hydrated, dramatic activation of catalytic competency can be achieved. © 1996 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Enhancement of (S)-naproxen ester productivity from racemic naproxen by lipase in organic solvents (1996)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 65 (1996), S. 156-162 
    Details
    ISSN: 0268-2575
    Keywords: lipase ; Naproxen ; esterification ; organic mixture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of enantioselective esterification of racemic Naproxen with trimethylsilyl methanol by Candida cylindracea lipase (triacylglycerol ester hydrolases, EC 3.1.1.3) were examined in various organic mixtures. The effects of solvent hydrophobicity on the activity, selectivity and stability of the enzyme and Naproxen solubility were investigated. Parabolic correlation for the dependence of the kinetic constants and Naproxen solubility on solvent hydrophobicity was found. A mixture of 60% isooctane and 40% toluene (v/v) was selected as the best reaction medium in which improvement of (S)-Naproxen ester productivity was obtained.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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