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  • Amphiphiles  (1)
  • FAB mass spectrometry  (1)
  • 1
    ISSN: 1573-4986
    Schlagwort(e): O-linked glycans ; acidic carbohydrates ; mucins ; human milk ; FAB mass spectrometry ; NMR spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract O-Linked glycans were isolated from human skim milk mucins or mucin-derived high-molecular weight glycopeptides and fractionated by anion exchange chromatography into neutral and acidic alditols. Major oligosaccharides contained in the acidic fraction were purified by high performance liquid chromatography and structurally characterized by a combination of fast atom bombardment mass spectrometry, methylation analysis and 500 MHz1H-nuclear magnetic resonance spectroscopy. The structural aspects exhibited by these major species in the acidic fraction resemble those established previously for the neutral oligosaccharides from human skim milk mucins: 1) the size of the alditols varies from tri- to decasaccharides 2) the core structure is of the ubiquitous type 2 3) the backbone sequences are of the poly-N-acetyllactosamine type with a particular preponderance of linearly extended GlcNAcβ(1–3)Gal (major) or GlcNAcβ(1–6)Gal units (minor). N-Acetylneuraminic acid on monosialylated (mucin- or glycopeptide-derived) and disialylated glycans (glycopeptide derived) is linked predominantly to position C-3 of galactose.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 0170-2041
    Schlagwort(e): Glycoconjugates ; Galactosides ; Steroid esters ; Amphiphiles ; Glycopeptides ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis of Galactose-Cluster-Containing Steroid DerivativesThe synthesis of galactose clusters that are linked to a steroid moiety by a peptide-like spacer unit is described. The galactose cluster is obtained by Koenigs-Knorr glycosylation of TRIS-Gly-Fmoc (2b) under Helferich conditions. Peptide and ester bonds are formed after activation of carboxylic acids as diphenylthiophene dioxide (TDO) esters. 6a is synthesized in a convergent way by coupling of (Ac4Gal)3-TRIS-Gly (3e) with cholesteryl TDO succinate (5b). Coupling of (Ac4Gal)3-TRIS-Gly hydrogen succinate (3f) with Gly-O-Chol (5d) by means of EEDQ yields 6d. Reaction of (Ac4Gal)3-TRIS-Gly-SUCC-O-TDO (3g) with 25-hydroxycholesterol leads in a linear sequence to the oxysterol derivative 6f. Selective cleavage of the acetyl groups from galactose units yields the known compound 6b and the new derivatives 6e and 6g.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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