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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1233-1238 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A kinetic study of the enzymatic hydrolysis of two celluloses with different structural features was performed at various temperatures (26-50°C). The enzymatic system consisted of three types of enzymes: E1 - β-1,4-glucan glucanohydrolase; E2 - β-1,4-glucan cellobiohydrolase; and E3 - β-glucosidase. A mathematical model for the mechanism of the hydrolysis of cellulosic materials catalyzed by a multienzymatic system was checked and a good rationalization of the experimental results was achieved. Uncompetitive and competitive glucose inhibition on E1 and E2, respectively, appeared to occur for both substrates. Inhibition by cellobiose was checked at 34°C on one substrate. The Vmax, Km, and glucose inhibition constants were optimized and their dependence on temperature determined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 102 (1982), S. 187-197 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Baumwollabfälle wurden einer verschieden dosierten γ-Bestrahlung unterworfen und in 10proz. NaOH-Lösungen aufgelöst. Die aus diesen Lösungen regenerierten Cellulosen wurden einer enzymatischen Hydrolyse unterzogen und der Verlauf der hydrolytischen Reaktion mit demjenigen an unbehandelten oder nur mit γ-Strahlen behandelten Cellulosen verglichen.Die einzelnen Muster wurden mittels Röntgenstreuung sowie Messungen des Polymerisationsgrades, der Feuchtigkeitsaufnahme und der Wasserretention charakterisiert. Es wurde eine wechselseitige Beziehung zwischen den durch die Vorbehandlungen hervorgerufenen strukturellen und morphologischen Modifizierungen und den Veränderungen der kinetischen Kenngrößen des enzymatischen Prozesses, im besonderen dem als Spezifizitätskonstante bezeichneten Verhältnis Vmax/Km festgestellt. Nur die Bestrahlung und die Auflösung gemeinsam ergaben eine bemerkenswerte Wirkungszunahme der enzymatischen Reaktion, während die Behandlung mit γ-Strahlen allein keine Zunahme der Hydrolyseausbeute bewirkte.
    Notes: Textile cotton wastes were irradiated with γ-rays at different doses and solubilized with 10% NaOH solutions. The regenerated products underwent enzymatic hydrolysis and their degradation pattern was compared with that of the cotton celluloses untreated or treated only with γ-rays. The different samples were characterized by measurements of X-ray diffraction, degree of polymerization, moisture regain and water retention. The structural and morphological modifications induced by the pretreatments were correlated with the variations of kinetic parameters, particularly the Vmax/Km ratio, defined as specificity constant. Only the combination of irradiation with dissolution pretreatments gave a considerable increase of hydrolysis reaction effectiveness.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 3329-3338 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Structural and morphological features of four different cellulosic materials have been deeped by X-ray, CP-MAS NMR, water retention, and specific surface area analysis. Hydrolysis time courses of two of these celluloses were followed by employing an enzymatic system consisting of a cellulase from Trichoderma viride and a cellobiase from Aspergillus niger. Experimental results were rationalized on the basis of a methematical model previously verified on the other two substrates. All the celluloses presented the same mechanistic framework involving product inhibitions. The most efficient pretreatment was found to be the dissolution of cellulosic material in the dimethyl sulfoxide-paraformaldehyde system and regeneration with ammonia. This treatment cancelled the memory of the initial structural order.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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