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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1047-1072 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, XLVII. - Synthesis of Tri- and Tetrasaccharide Sequences of N-Glycoproteins Including a β-D-Mannosidic LinkageThe trisaccharides α-D-Man-p-(1 → 6)-β-D-Man-p-(1 → 4)-D-GlcNAc (37) and α-D-Man-p-(1 → 3)-β-D-Man-p-(1 → 4)-D-GlcNAc (43) as well as the key tetrasaccharide α-D-Man-p-(1 → 3)-[α-Man-p-(1 → 6)]-β-D-Man-p-(1 → 4)-D-GlcNAc (51), which are parts of the carbohydrate chain of N-glycoproteins, have been synthesized. In this case the most important reaction is the direct synthesis of a β-mannoside linkage of D-mannos with 2-acetamido-2-deoxy-D-glucose. This problem has been solved by coupling of the halide 10 with the hydroxy component 14 in the presence of silver silicate which leads to the disaccharide 17. The product 17 is the fundamental compound for building up more complexed oligosaccharides.
    Notes: Die im Kohlenhydrat-Teil von N-Glycoproteinen enthaltenen Trisaccharide α-D-Man-p-(1 → 6)-β-D-Man-p-(1 → 4)-D-GlcNAc (37) und α-D-Man-p-(1 → 3)-β-D-Man-p-(1 → 4)-D-GlcNAc (43) und das Schlüsseltetrasaccharid α-D-Man-p-(1 → 3)-[α-D-Man-p-(1 → 6)]-β-D-Man-p-(1 → 4)-D-GlcNAc (51) wurden synthetisiert. Die wichtigste Reaktion ist hierbei die direkte Herstellung der β-D-mannosidischen Verknüpfung zwischen D-Mannose und 2-Acetamido-2-desoxy-D-glucose. Die Verknüpfung gelingt durch Umsetzung des Halogenids 10 und der Hydroxylkomponente 14 mit Hilfe des Silbersilicat-Verfahrens zum Disaccharid 17. Das Produkt 17 ist die Schlüsselsubstanz für alle weiteren Aufbaureaktionen zu höheren Oligosacchariden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Confomational Analysis, XXIV. - determination of the Conformations of Tri-and Tetrasaccharide Sequences of N-Glycoproteins. The problem of the (1 → 6)-glycosidic BondThe preferred solution conformations of the saccharides α-D-Man(1 → 3)-β-D-Man(1 → 4)-D-GIcNAc (1), α-D-Man(1 → 6)-β-Man(1 → 4)-D-GIcNAc (2), and α-D-Man(1 → 3)[α-D-Man(1 → 6)]lβ-D-Man(1 → 4)-D-GIcNAc3), which are known as parts of the core structure of N-glycoproteins, could be established by use of HSEA calculations (HSEA: Hard-Sphere Exo-Anomeric) with the new program GESA (= Geometry of Saccharides) in connection with 1H NMR investigations like NOE experiments, spin-lattice relaxation-time measurements and the observation of selective deshieldings. (1 → 3)- and (1 → 4)-glycosidic bonds show one strongly preferred conformation. The greater flexibility of the (1 → 6)-glycosidic bonds show one strongly preferred conformation. The greater flexibility of the (1 → 6)-glycosidic bond will be discussed in details. For the spectra analysis various 2-D techniques have been used.
    Notes: Von den Sacchariden α-D-Man(1 → 3)-β-D-Man(1 → 4)-D=-GICNAc (1), α-D-Man(1 → 6)-β-D-Man(1 → 4)-D-GIcNAc(2) und α-D-Man(1 → 3)[α-D-Man(1 → 6)]-β-D-Man(1 → 4)-D-GlcNAc(3), die als Core-Struktur in N-Glycoproteinen vorkommen, wurden durch HSEA-Berechnungen (HSEA: Hard-Sphere Exo-Anomeric) mit dem neuen GESA-Programm (GESA: Geometry of Saccharides) die bevorzugten Konformationen bestimmt. Mit Hilfe von 1H-NMR-Experimenten, nämlich NOE-Experimenten, Spin-Gitter-Relaxationszeitmessungen und der Beobachtung selektiver Entschirmungen, ließen sich diese Konformationen in Lösung bestätigen. (1 → 3)- und (1 → 4)-glycosidische Bindungen weisen eine stark bevorzugte Konformation auf. Die weitaus größere Flexibilität der (1 → 6)-glycosidischen Bindung wird besonders diskutiert. Zur Analyse der Spektren wurden verschiedene 2-D-NMR-Techniken angewandt.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conformational Analysis, XXV. - Conformations of Octasaccharide and Pentasaccharide Sequences in N-Glycoproteins of the Lactosamine TypeThe oligosaccharide sequences [β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)]β-D-Gal-(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (2), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (3), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)-α-D-Man(1 → 3)β-D-Man(1 → 4)-D-GlcNAc (4), and β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man-OMe (5), found in N-glycoproteins, were investigated by means of HSEA calculations with the program GESA to reveal the preferred solution conformations of these compounds. Experimental evidence of the calculated conformations was given by 1H and 13C NMR studies like NOE experiments, spin-lattice relaxation-time measurements and observation of special deshielding effects. NMR spectra analysis required application of 2-D-NMR techniques. As a conclusion of experimental and theoretical results the common sequences in the saccharides 2, 3, 4, and 5 exhibit very similar conformations. The pentasaccharide 4 takes up a linear conformation whereas 5 shows a bent arrangement of the pyranose rings (‚gt conformation‘) which results in a relatively close contact between the α-D-Man unit and the reducing D-GlcNAc unit. Analogously, both conformations, the linear and the bent one, occur in the octasaccharide 2.
    Notes: Die bevorzugten Konformationen der in N-Glycoproteinen vorkommenden Oligosaccharid-Sequenzen [β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)] β-D-Gal(1 → 4)β-D-GlcNAc-(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (2), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (3), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)-β-D-Man(1 → 4)-D-GlcNAc (4) und β-D-Gal(1 → 4)β-D-GlcNA(1 → 2)α-D-Man-OMe (5) wurden durch HSEA-Berechnungen mit dem Programm GESA bestimmt. Die Überprüfung der Rechnungen erfolgte durch 1H- und 13C-NMR-spektroskopische Experimente wie NOE-Untersuchungen, Spin-Gitter-Relaxationszeitmessungen und Beobachtung spezieller Abschirmungseffekte. Die Interpretation der NMR-Spektren erfolgte mit Hilfe von 2-D-NMR-Techniken. Die in 2, 3, 4, und 5 gemeinsam auftretenden Sequenzen haben alle sehr ähnliche bevorzugte Konformationen. Während 4 eine weitgehend gestreckte Konformation aufweist, zeigt 5 bevorzugt eine gebogene gt-Konformation, bei der die α-D-Man-Einheit der reduzierenden D-GlcNAc-Einheit nahe steht. Beide Formen kommen in 2 entsprechend vereint vor.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 21 (1982), S. 926-927 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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