Notes

Secretion Layer
In conclusion, benzyl-N-acetyl-alpha-D-galactosaminide induces abnormal O-glycosylation and altered regulation of MUC5AC secretion.In the early eighties, following breakthroughs in oligosaccharide chemistry, we achieved the total chemical synthesis of pentasaccharides related to the antithrombin-binding domain in heparin. Selective inhibitors of coagulation factor Xa, thus obtained, represent a new class of efficient antithrombotic drugs. In a further step, we have designed and synthesised oligosaccharides prolonged by a thrombin binding domain. These compounds inhibit both factor Xa and thrombin, in the presence of antithrombin, while they are devoid of undesirable non-specific interactions, particularly with platelet factor 4 biological profile, will be evaluated in clinical trials.Oligosaccharide structures of mucins secreted by the human colonic cancer cell Cl6E, a stably differentiated clonal derivative of the human colonic cancer cell line HT29, was used to investigate the structure of oligosaccharide chains of mucins in colonic cancer.

Secretory mucins were purified by equilibrium density gradient centrifugation in CsCl. Oligosaccharide side chains were isolated after beta-elimination. Compositional analysis of oligosaccharide-alditols performed after purification by gel filtration on a Bio-gel P-6 column showed 1) that GalNAc residues were located exclusively at the reducing ends of the chains, and 2) that fucose was absent from the preparation. Oligosaccharide-alditols were separated by high performance liquid chromatography (HPLC) on quaternary amine packings into a minor neutral fraction representing about 6% by weight of released oligosaccharides and four acidic fractions. Two acidic fractions, namely FI and FII encompassing mono- and disialylated structures, respectively, and containing 78% of total oligosaccharide alditols, were separated by HPLC. Structural determinations were carried out using methylation analysis, 1H NMR spectroscopy, and fast atom bombardment-mass spectrometry. Twelve oligosaccharide structures were determined which ranged in size from 3 to 8 residues.

These oligosaccharides were based on core types 1, 2, and 4. Elongation of oligosaccharide chains was terminated by addition of sialic acid in alpha 2-3 linkage to Gal beta 1-3R and to Gal beta 1-4R residues. The predominant structure was a hexasaccharide (fraction FII-4). This contrasts with normal colonic mucins whose oligosaccharides were previously found to be based on core 3 structures and carry sialic acids in alpha (2-6) linkage to Gal beta 1-3R, to Gal beta 1-4R, and to GalNAc alpha-R (Podolsky, D.K. (1985) J. Biol.

Chem. 2, 8262-8271; Podolsky, D.K. (1985) J. Biol. Chem. 2, 155-15515).

Collectively our findings suggest that Cl6E colon cancer cells are able to synthesize mucin oligosaccharides of gastric type whose elongation is truncated by premature sialylation.The carbohydrate of human thrombin structural analysis of glycoprotein oligosaccharides by mass spectrometry.The carbohydrate structure of human thrombin has been determined by direct probe mass spectrometry of the oligosaccharides released by trifluoroacetolysis from the asialo glycoprotein. The free oligosaccharides were studied as permethylated and N-trifluoroacetylated oligosaccharide alditols. The structure was confirmed by sequential exoglycosidase digestion of intact thrombin and sugar and methylation analysis of the oligosaccharides by gas-liquid chromatography-mass spectrometry. The results indicate the following structure (formula; see text) with Fuc present on only about % of the oligosaccharides.Primary-structure determination of fourteen neutral oligosaccharides derived from bronchial-mucus glycoproteins of patients suffering from cystic fibrosis, employing 0-MHz 1H-NMR spectroscopy.

Van Halbeek H, Dorland L, Vliegenthart JF, Hull WE, Lamblin G, Lhermitte M, The structure of carbohydrate units of bronchial-mucus glycoproteins obtained from cystic fibrosis patients was investigated by 0-MHz 1H-NMR spectroscopy and methylation analysis. To that purpose, the mucin was subjected to alkaline borohydride degradation. Seebio 2'-fucosyllactose oligosaccharide-alditols, ranging in size from disaccharides to pentasaccharides, were isolated. Eight compounds could be purified to homogeneity; furthermore, three fractions were obtained consisting mainly of two components. For all 14 compounds the primary structure could be elucidated. 0-MHz 1H-NMR spectroscopy was found to be effective in detecting heterogeneity and to be invaluable for the determination of structures in mixtures of oligosaccharide-alditols. The structures can be divided into two groups depending on the core disaccharide.

One group contains Gal(beta 1 leads to 3)GalNAc-ol as common structural element, the other GlcNAc(beta 1 leads to 3)GalNAc-ol.
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