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  • 1
    Electronic Resource
    Electronic Resource
    Bacterial α-glucan phosphorylases (1999)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 171 (1999), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Although glycogen and other α-1,4-d-glucan storage polysaccharides are present in many bacteria, only few glucan phosphorylases from bacteria have been identified and characterised on the protein or gene level. All bacterial phosphorylases follow the same catalytic mechanisms as their plant and vertebrate counterparts, but differ considerably in terms of their substrate specificity and regulation. The catalytic domains are highly conserved while the regulatory sites are only poorly conserved. The degree of conservation between bacterial and mammalian phosphorylases is comparable to that of other non-mammalian and mammalian α-glucan phosphorylases. Only for maltodextrin phosphorylase from E. coli the physiological role of the enzyme in the utilisation of maltodextrins is known in detail; that of all other phosphorylases remains still unclear. Roles in regulation of endogenous glycogen metabolism in periods of starvation, and sporulation, stress response or quick adaptation to changing environments are imaginable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1999.tb13414.x
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  • 2
    Electronic Resource
    Electronic Resource
    Induction of aldose reductase and xylitol dehydrogenase activities in Candida tenuis CBS 4435 (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 149 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In this study the ability of various sugars and sugar alcohols to induce aldose reductase (xylose reductase) and xylitol dehydrogenase (xylulose reductase) activities in the yeast Candida tenuis was investigated. Both enzyme activities were induced when the organism was grown on d-xylose or l-arabinose as well as on the structurally related sugars d-arabinose or d-lyxose. Mixtures of d-xylose with the more rapidly metabolizable sugar d-glucose resulted in a decrease in the levels of both enzymes formed. These results show that the utilization of d-xylose by C. tenuis is regulated by induction and catabolite repression. Furthermore, the different patterns of induction on distinct sugars suggest that the synthesis of both enzymes is not under coordinate control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb10304.x
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  • 3
    Electronic Resource
    Electronic Resource
    Maltodextrin Phosphorylase from Escherichia coli: Production and Application for the Synthesis of α-Glucose-1-Phosphate (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 782 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb40562.x
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  • 4
    Electronic Resource
    Electronic Resource
    Optimization of Glucose-l-Phosphate Production Employing Glucan-Phosphorylases in Continuous Enzyme Membrane Reactors (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 799 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb33245.x
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  • 5
    Electronic Resource
    Electronic Resource
    Synergism of Trichoderma reesei cellulases while degrading different celluloses (1993)
    Springer
    Biotechnology letters 15 (1993), S. 71-76 
    Details
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The synergistic action of purified cellulases from Trichoderma reesei in hydrolysis of cellulose decreased with increasing substrate concentration, depended strongly on the the type of cellulose used, and was maximal on crystalline cellulose. Contrarily, the activity of the individual cellulases was highest on amorphous cellulose. The binary combinations CBH I/EG III and CBH I/CBH II exhibited the greatest degree of synergism on crystalline cellulose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00131556
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  • 6
    Electronic Resource
    Electronic Resource
    Continuous production of α,α-trehalose by immobilised fungal trehalose phosphorylase (1999)
    Springer
    Biotechnology techniques 13 (1999), S. 243-248 
    Details
    ISSN: 1573-6784
    Keywords: immobilisation ; trehalose production ; trehalose phosphorylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Immobilisation of trehalose phosphorylase from Schizophyllum commune by adsorption onto anion-exchange materials stabilised the enzyme activity at 30 °C by approx. 35-fold. Immobilised and free enzymes showed similar pH-dependence of activity but different inactivation behavior above 30 °C. A fixed-bed enzyme reactor produced α,α-trehalose at a stable substrate conversion of 80% with a productivity of 2.6 g l−1 h−1 for 72 h. Inhibition of trehalose phosphorylase by phosphate limited the productivity of a direct conversion of starch into α,α-trehalose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008986623007
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  • 7
    Electronic Resource
    Electronic Resource
    A new approach for modeling cellulase-cellulose adsorption and the kinetics of the enzymatic hydrolysis of microcrystalline cellulose (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 469-479 
    Details
    ISSN: 0006-3592
    Keywords: cellulase ; cellulose ; adsorption ; kinetics ; mathematical model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two fractions of substrate in microcrystalline cellulose which differ in their adsorption capacities for the cellulases and their susceptibility to enzymatic attack have been identified. On the basis of a two-substrate hypothesis, mathematical models to describe enzyme adsorption and the kinetics of hydrolysis have been derived. A new nonequilibrium approach was chosen to predict cellulase-cellulose adsorption. A maximum binding capacity of 76 mg protein per gram substrate and a half-maximum saturation constant of 26 filter paper units (FPU) per gram substrate have been calculated, and a linear relationship of hydrolysis rate vs. adsorbed protein has been found. The fraction of substrate more easily hydrolyzed, as calculated from hydrolysis data, represents 19% of the total effective substrate concentration. This fraction is only slightly different from that of other celluloses and has been estimated to be 27% and 30% for NaOH- and H3PO4-swollen cellulose, respectively. The effective substrate concentration is equal to the maximum amount of the substrate which can be converted during exhaustive hydrolysis. This in turn is determined by the overall degradability of the substrate by the cellulases (85-90% for microcrystalline cellulose) and by the cellobiose concentration during hydrolysis. The kinetic model is based on a summation of two integrated first-order reactions with respect to the effective substrate concentration. Furthermore, it includes the principal factors influencing the reaction rates: the ratio of filter paper and β-glucosidase units per gram substrate and the initial substrate concentration. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420410
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  • 8
    Electronic Resource
    Electronic Resource
    Specific quantification of trichoderma reesei cellulases in reconstituted mixtures and its application to cellulase-cellulose binding studies (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 961-966 
    Details
    ISSN: 0006-3592
    Keywords: cellobiohydrolase ; endoglucanase ; adsorption ; hydrolytic efficiency ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Specific quantifications of the major cellulolytic components of the Trichoderma reesei enzyme complex, i.e., endoglucanases I and III and cellobiohydrolases I and II, are described and, employing a defined mixture of these four cellulases reconstituted according to the composition of the native Trichoderma cellulase complex, used to determine the binding of each individual component onto filter paper. During substrate degradation by this enzyme mixture, the specific adsorption of each individual cellulase gradually increases and no preferential binding of one enzyme component in any particular phase of cellulose hydrolysis is found. T. reesei cellobiohydrolases I and II admixed with endoglucanases I and III represent a “full-value” cellulase system that is capable of degrading semicrystalline cellulose efficiently. In comparison with the crude Trichoderma enzyme complex, almost identical adsorption properties and similar hydrolytic efficiency are found for the reconstituted mixture. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440812
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  • 9
    Electronic Resource
    Electronic Resource
    Continuous enzymatic production of xylitol with simultaneous coenzyme regeneration in a charged membrane reactor (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 52 (1996), S. 387-396 
    Details
    ISSN: 0006-3592
    Keywords: xylitol ; NADH regeneration ; charged membrane ; continuous production ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have developed a new process for the production of xylitol from D-xylose by enzyme technology. An NADH-dependent xylose reductase (XR) from Candida tenuis catalyzes the reduction of xylose, which is coupled to enzymatic oxidations of D-glucose or D-xylose by glucose dehydrogenase from Bacillus cereus to make achievable an up to 10,000-fold regeneration of NADH per cycle of discontinuous conversion. Using a simple kinetic model as a tool for process optimization, suitable conditions with regard to performance and stability of the multi-component reaction system were established, and 300 g/L of substrate could be converted in yields above 96% in one single batch reaction. Due to selective and over 98% complete retention of the native coenzyme by negatively charged nanofiltration membranes used in a continuously operated enzyme reactor, a specific productivity of 80 g xylitol per liter, day, and kilounit of XR was maintained over the 150-h reaction time with only a single dosage of NADH. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Improved operational stability of cell-free glucose-fructose oxidoreductase from Zymomonas mobilis for the efficient synthesis of sorbitol and gluconic acid in a continuous ultrafiltration membrane reactor (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 623-629 
    Details
    ISSN: 0006-3592
    Keywords: glucose-fructose oxidoreductase ; Zymomonas mobilis ; free enzyme ; continuous production ; stability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the continuous, enzymatic synthesis of sorbitol and gluconic acid by cell-free glucose-fructose oxidoreductase (GFOR) from Zymomonas mobilis, the principal determinants of productivity have been identified. Most important, the rapid inactivation of the soluble enzyme during substrate conversion can be avoided almost completely when weak bases such as tris(hydroxymethyl)aminomethan or imidazol are used for the titration of the produced gluconic acid and when 5-10 mM dithiothreitol are added to prevent thiol oxidations. With regard to a long-term operational stability of the enzyme for continuous syntheses, thermal deactivation becomes significant at reaction temperatures above 30°C. Without any additional purification being required, the crude cell extract of Z. mobilis can be employed in a continuous ultrafiltration membrane reactor over a time period of more than 250 h without significant decrease in substrate conversion or enzyme activity. The use of soluble GFOR thus appears to be an interesting alternative to employing permeabilized cells of Zymomonas for the production of sorbitol and gluconic acid and may be superior with regard to reactor productivities, at comparable operational stabilities. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 623-629, 1997.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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