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  • 1
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 147-155 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Employing anionic and non-ionic cellulose ethers, differing in type of substituent and degree of substitution, as substrates, the pH-profile of enzyme activity and the parameter Km and Vmax of the MICHAELIS-MENTEN kinetics have been determined with Penicillium citrioviride cellulase in an homogeneous system. Within rather wide limits, a linear correlation was found between the DS of the substrate and Km or Vmax, respectively. Also the pH-profile was found to depend on DS mainly, being bimodal at higher DS. On the other hand, no significant difference was observed between anionic and non-ionic cellulose ethers of about the same DS with regard to the parameters determined. It is assumed, that substrate-enzyme interaction is governed mainly by the length of non-derivatized chain sequences mainly and not by Coulomb interactions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using as substrates various water-soluble cellulose derivatives differing in DS and type of substituent, the efficiency of enzyme action in dependence of pH and the “CMC ase activity” of a Gliocladium spec. cellulase was investigated, stressing the significant role of effective charge density in connection with the results obtained with ionic derivatives of cellulose. From the results conclusions are drawn with regard to the proper choice of the substrate in determining CMC-ase activity.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Starting from cotton linters cellulose modified in physical structure type of lattice, degree of order, state of swelling by different pretreatments, and from culture filtrates of Gliocladium spec., the initial stage of enzymatic hydrolysis of cellulose has been investigated. Especially with substrates of high degradability a considerable effect of stirring on rate of formation of soluble products was found. For linerization of yield-vs-time-curves (% residue resp. 7percnt; solubles as a criterion for yield), a 2-parameatric first order rate law was found to be suitable within a limited time interval, values of k1 were higher and for the accessible part of the substrate were lower in the initial stage of hydrolysis than in the later one. The MICHAELIS-MENTEN-constant kM has been determined for substrates of different physical structure after different times of reaction. Data found for kM indicated a stronger dependence of kM on reaction time than on physical structure of the substrate under conditions applied.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 8 (1988), S. 233-240 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The gelpermeation chromatography of sodium ligncsulfonates with bidistilled water as an eluent is influenced by the volume expansion of the polyelectrolyte, by the negative changes of the gels, and by the inclusion effect so markedly that true conclusions on the molecular weight distribution of sodium lignosulfonate cannot be drawn. Using electrolytes as an eluent these irregularities can be avoided. Polydispersity of these macromolecules however prevents separation into discrete peaks. As a result of this behaviour changes of molecular weight distribution are only poorly recognized. Therefore, on studying biotransformation of lignosulfonic acids we purpose to use gels by which one part of the lignosulfonates is excluded, and biotransformation may be controlled by the ratio of excluded part of the lignosulfonates to that part retarded by the gels.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Samples of Na-carboxymethyl cellulose with DS between 0.5 and 1.7 were degraded enzymatically by a culture filtrate of Gliocladium spec. The degradation was measured by viscosimetry and by determination of the content of glucose and of reducing sugars. The results are discussed with regard to hydrolyzable and non-hydrolyzable glycosidic bonds, composition and length of fragments formed, and by considering the distribution of substituted and non-substituted monomer units along the chain. In the range of DS 0.5 to 0.8 the enzymatic hydrolysis depends not only on DS, but also on the procedure applied for preparing samples having different distribution of substituents along and between the polymer chains.
    Notes: Na-Carboxymethylcellulose-Proben mit DS-Werten zwischen 0,5 und 1,7 wurden dem enzymatischen Abbau mit einem Kulturfiltrat von Gliocladium spec. unterworfen. Zur Charakterisierung des Abbauverlaufes dienten Viskositätsmessungen, sowie die Bestimmung des Gehaltes an Glucose und an reduzierenden Zuckern. Die Ergebnisse werden im Hinblick auf spaltbare bzw. nicht spaltbare Glucosidbindungen im Substrat, die Länge und Art der Spaltstücke und die Verteilung substituierter und unsubstituierter Monomereinheiten entlang der Polymerkette diskutiert. Im DS- Bereich zwischen 0,5 und 0,8 hängt der Verlauf der enzymatischen Hydrolyse nicht nur vom DS, sondern auch von der Herstellungsweise und der dadurch bedingten unterschiedlich gleichmäßigen Verteilung der Substituenten längs der Kette und zwischen den Ketten ab.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The homogeneus hydrolytic by cellulose degrading enzymes (Gliocladium spec., Trichoderma viride) of water-soluble carboxyethyl cellulose (DS 0.2 to 0.5) was investigated by viscosimetry and determining the resulting amount of glucose. The low values of DS of the samples achieved without reducing the solubility in water allows extrapolation to the properties of unsubstituted cellulose. The formation of glucose enables to draw conclusions to the selectivity of the scission of glucose bridges by the enzymes.
    Notes: Die homogene Hydrolyse durch cellulolytische Enzymsysteme (Gliocladium spec., Trichoderma viride) von wasserlöslichen Carboxyethylcellulosen (DS-Bereich 0,2 bis 0,5) wurde viskosimetrisch und über die Bestimmung der gebildeten Glucose verfolgt. Der bei diesen Präparaten unter Erhaltung der Wasserlöslichkeit zugänglliche niedrige DS ermöglicht eine Extrapolation auf das Verhalten der unsubstituierten Cellulosekette. Der Verlauf der Glucosebildung läßt Rückschlüsse auf die Selektivität der Glucosidbrückenspaltung durch das Enzymsystem zu.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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