H-1-NMR ANALYSIS OF NOVEL SIALYLATED AND FUCOSYLATED LACTOSE-BASED OLIGOSACCHARIDES HAVING LINEAR GLCNAC(BETA-1-6) GAL AND NEU5AC(ALPHA-2-6) GLCNAC SEQUENCES

Three novel oligosaccharides of human infant faeces have been fully ch aracterised by methylation analysis and 500/600 MHz H-1 NMR spectrosco py including DQF-COSY, TQF-COSY, TOCSY and ROESY experiments. The olig osaccharides were shown to be lactose-based structures two of which we re substituted at C-6 of Gal with either the Le(x) trisaccharide, Gal( beta 1-4)[Fuc(alpha 1-3)]GlcNAc(beta 1-, or Neu5Ac(alpha 2-6)Gal(beta 1-4)GlcNAc(beta 1-. They differ from other free oligosaccharides previ ously isolated from the human by having the (1 --> 6) linkage to Gal i n the absence of a (1 --> 3) branch. The third oligosaccharide has Neu 5Ac(alpha 2-6) linked to GlcNAc of the trisaccharide GlcNAc(beta 1-3)G al(beta 1-4)Glc. This is a linear fragment of the disialylated tetrasa ccharide sequence Neu5Ac(alpha 2-3)Gal( beta 1-3)[Neu5Ac(alpha 2-6)]Gl cNAc(beta 1- found in the milk oligosaccharide disialyl LNT (the GlcNA c residue of the tetrasaccharide linked to lactose) and also of N-link ed chains (GlcNAc linked to Man). (C) 1997 Elsevier Science Ltd.