| 15361072 |
Robbe C, Capon C, Coddeville B, Michalski JC: Structural diversity and specific distribution of O-glycans in normal human mucins along the intestinal tract. Biochem J. 2004 Dec 1;384(Pt 2):307-16.
Purified human mucins from different parts of the intestinal tract (ileum, cecum, transverse and sigmoid colon and rectum) were isolated from two individuals with blood group ALe (b) (A-Lewis (b)). After alkaline borohydride treatment the released oligosaccharides were structurally characterized by nano-ESI Q-TOF MS/MS (electrospray ionization quadrupole time-of-flight tandem MS) without prior fractionation or derivatization. More than 100 different oligosaccharides, with up to ten monosaccharide residues, were identified using this technique. Oligosaccharides based on core 3 structures, GlcNAc (beta1-3) GalNAc (where GlcNAc is N-acetyl-D-glucosamine and GalNAc is N-acetylgalactosamine), were widely distributed in human intestinal mucins. Core 5 structures, GalNAc (alpha1-3) GalNAc, were also recovered in all fractions. Moreover, a comparison of the oligosaccharide repertoire, with respect to size, diversity and expression of glycans and terminal epitopes, showed a high level of mucin-specific glycosylation: highly fucosylated glycans, found specifically in the small intestine, were mainly based on core 4 structures, GlcNAc-(beta1-3)[GlcNAc (beta1-6)] GalNAc, whereas the sulpho-Le (X) determinant carrying core 2 glycans, Gal (beta1-3)[GlcNAc (beta1-6)]-GalNAc (where Gal is galactose), was recovered mainly in the distal colon. Blood group H and A antigenic determinants were present exclusively in the ileum and cecum, whereas blood group Sd (a)/Cad related epitopes, GalNAc (beta1-4)[NeuAc (alpha2-3)] Gal (where NeuAc is N-acetylneuraminate), were found to increase along the length of the colon. Our findings suggest that mucins create an enormous repertoire of potential binding sites for micro-organisms that could explain the regio-specific colonization of bacteria in the human intestinal tract. |
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