Novel polyfucosylated N-linked glycopeptides with blood group A, H, X and Y determinants from human small intestinal epithelial cells

Abstract

A novel type of N-linked glycopeptides representing a major part of the glycans in human small intestinal epithelial cells from blood group A and O individuals were isolated by gel filtrations and affinity chromatography on concanavalin A-Sepharose and Bandeiraea simplicifolia lectin I-Sepharose. Sugar composition, methylation analysis, 1H NMR spectroscopy of the underivatized glycopeptides and FAB-mass spectrometry and electron impact-mass spectrometry of the permethylated glycopeptides indicated a tri- and tetra-antennary structure containing an intersecting N-acetylglucosamine and an α(1->6)-linked fucose residue in the core unit for the majority of the glycans. In contrast to most glycopeptides of other sources, the intestinal glycopeptides were devoid of sialic acid, but contained 6-7 residues of fucose. The outer branches contained the following structures: Fucα1-2Galβ1-3GleNAcβ1- (H type 1) Fucα1-2Galβ1-4GleNAcβ1- (H type 2) Galba1-4(Fucα1-3)GlcNAcβ1- (X) Fucα1-2Galβ1-4(Fucα1-3)GleNAcβ1- (Y) GalNAcα1-3(Fucα1-2)Galβ1-3GleNAcβ1- (A type 1) GalNAcα1-3(Fucα1-2)Galβ1-4GleNAcβ1- (monofucosyl A type 2) GalNAcα1-3(Fucα1-2)Galβ1-4 (Fucα1-3)GlcNAcβ1- (trifucosyl A type 2) The blood group determinant structures were mainly of type 2, whereas glycolipids from the same cells contained mainly type 1 determinants. The polyfucosylated glycans represent a novel type of blood group active glycopeptides. The unique properties of the small intestinal glycopeptides as compared with glycopeptides of other tissue sources may be correlated with the specialized functional properties of the small intestinal epithelial cells.