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  • 1
    Electronic Resource
    Electronic Resource
    Induction of cellulose- and xylan-degrading enzyme complex in the yeast Trichosporon cutaneum (1984)
    Springer
    Archives of microbiology 138 (1984), S. 371-376 
    Details
    ISSN: 1432-072X
    Keywords: Cellulase ; β-Glucosidase ; β-Xylanase ; β-Xylosidase ; Trichosporon cutaneum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The specificity of induction of cellulose- and xylan-degrading enzymes was investigated on the yeast strain Trichosporon cutaneum CCY 30-5-4 using series of compounds structurally related to cellulose and xylan, including monosaccharides, glycosides, glucooligosaccharides and xylooligosaccharides. Determination of activities of secreted cellulase and β-xylanase, intracellular, cell wall bound and extracellular β-glucosidase and β-xylosidase revealed that: (1) The synthesis of xylan-degrading enzymes is induced in the cell only by xylosaccharides, 1,3-β-xylobiose, 1,2-β-xylobiose, 1,4-β-xylosyl-L-arabinose, 1,4-β-xylobiose and thioxylobiose being the best inducers. The xylan-degrading enzymes show different pattern of development in time and discrete cellular localization, i.e. intracellular β-xylosidase precedes extracellular β-xylanase. (2) A true cellulase is not inducible by glucosaccharides and cellulose. Negligible constitutive cellulase activity was detected which was about two orders lower than an induced cellulase in the typical cellulolytic fungus Trichoderma reesei QM 9414. (3) The best inducer of intracellular β-glucosidase splitting cellobiose was thiocellobiose in a wide range of concentration (0.1–10 mM), whereas xylosaccharides at high concentrations induced β-xylosidase of xylobiose type and a non-specific aryl β-D-glucosidase. The results were confirmed by growing cells on cellulose and xylan. T. cutaneum was found to be a xylan-voracious yeast, unable to grow on cellulose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410906
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  • 2
    Electronic Resource
    Electronic Resource
    Fast atom bombardment and collisional activation mass spectrometry of oligosaccharides related to xylans (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 17 (1988), S. 455-458 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The positive ion fast atom bombardment (FAB) mass spectra of oligosaccharides related to D-xylan and D-glucurono-D-xylans were investigated. Although the mass spectra of the underivatized oligosaccharides are relatively weak, they still offer reliable information on the molecular weight of these compounds from their [M + H]+ and [M + H + glycerol]+ ions. Esterification, glycosidation and/or partial methylation improve the relative abundances of the molecular and fragment ions with respect to those of the glycerol matrix. The mass spectra of these derivatized compounds also allow the determination of the mass of the monosaccharide units by the occurrence of more abundant and characteristic fragment ions. The differently linked D-xylobioses of the (1 → 2), (1 → 3) and (1 → 4) type cannot be distinguished on the basis of their mass spectra alone. The collisional activation (CA) spectra of the [M + H + glycerol]+ adduct ions, however, revealed that an unequivocal determination of the type of linkage in these isomers is possible. The small values of the discrepancy factors in the FAB CA spectra prove that CA mass spectrometry is, also in combination with FAB ionization, the most precise of the current mass spectrometric techniques.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200170607
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  • 3
    Electronic Resource
    Electronic Resource
    Electron impact, chemical ionization and collisional activation mass spectrometry of methyl O-acetyl-β-D-xylopyranosides (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 49-58 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectrometric behaviour of methyl O-acetyl-β-D-xylopyranosides has been studied using electron impact, methane and ammonia chemical ionization and collisional activation mass spectrometry. Based on this study the fragmentation of the compounds studied has been described. The structures of ions occurring after elimination of ketene in the fragmentation reactions of acetylated saccharides were studied by using the MNDO semi-empirical quantum chemical method. Calculated geometrical parameters (bond lengths, bond and torsional angles), distribution of net atomic charges and the difference in heat of formation (70 kJ mol-1) between the keto and enol isomers of [C5H7O3]+ ions studied predict that the enol structure is more stable thermodynamically than its corresponding keto isomer.The electron impact and chemical ionization mass spectra do not provide complete information for determination of the location of acetyl groups in methyl O-acetylpentopyranosides. The number and position of the acetyl groups however, can be determined unambiguously from collisional activation mass spectra of the [M - OCH3]+ ions. The reproducibility of the mass spectral data, obtained by the applied mass spectral methods was evaluated by calculation of discrepancy factors. From this point of view the collisional activation method is approximately five times more precise than electron impact and 10 times more precise than chemical ionization methods.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200120202
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis of methyl α-isomalto-oligosaccharides specifically deoxygenated at position 2 of the terminal glycopyranosyl unit (1994)
    Springer
    Glycoconjugate journal 11 (1994), S. 17-22 
    Details
    ISSN: 1573-4986
    Keywords: Methyl α-isomalto-oligosaccharides ; tert-butyl(dimethyl)silyl donor ; 2-deoxy-α-d-arabino-hexopyranosyl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Methyl α-isomaltoside and methyl α-isomaltotrioside specifically deoxygenated at position C-2 of the terminal glucopyranosyl unit were synthesized by trimethylsilyltriflate-mediated condensation of 3,4,6-tri-O-benzoyl-1-O-tert-butyl(dimethyl)silyl-2-deoxy-β-d-arabino-hexopyranose with suitably blocked derivatives of methyl α-d-glucopyranoside and methyl α-isomaltoside, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00732428
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  • 5
    Electronic Resource
    Electronic Resource
    Assignment of carbonyl carbon and acetyl methyl proton resonances of acetylated saccharides by the use of two-dimensional NMR techniques (1990)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 979-987 
    Details
    ISSN: 0749-1581
    Keywords: Long-range correlation ; Long-range couplings ; Selective pulses ; Peracetylated saccharides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbonyl carbons in peracetylated saccharides are coupled via three- and two-bond couplings with ring protons and acetyl methyl protons, respectively. Using their mean values, the optimum setting for 2D heterocorrelated experiments (Freeman-Morris and COLOC sequences) designed for the assignment of carbonyl carbon and acetyl methyl proton resonances is presented. Selective inversion of the methyl proton resonances in the middle of the refocusing period is introduced. This modification eliminates the effect of 2J(CO,CH3) on the intensity of the carbonyl carbon-ring proton cross-peaks, which is essential in the assignment procedure. The carbonyl carbon, acetyl methyl and ring proton resonances can be used for the determination of the primary structure of complex saccharides.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260281113
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