Structural characterization of sialylated tetrasaccharides and pentasaccharides with blood group H and Le(x) activity isolated from bovine submaxillary mucin

In this study we have investigated the structures of a sialylated tetrasaccharide and two sialylated pentasaccharides released from bovine submaxillary mucin by alkaline borohydride treatment and isolated by high-performance liquid chromatography. The tetrasaccharide contained NeuGc, while one of the pentasaccharides contained NeuAc and the other contained NeuGc. All three oligosaccharides contained the core type-3 structure (GlcNAc beta 1----3GalNAcol). The structures, determined by a combination of one- and two-dimensional 1H-NMR spectroscopy at 270 MHz and methylation analysis involving gas-liquid chromatography/mass spectrometry, were as follows: formula: see text]. The oligosaccharides occurred in the approximate molar ratios, 1.0:0.6:0.3. This is the first report of these oligosaccharides in bovine submaxillary mucin. 1H-NMR data for structures A1/2c and A1/2e, which are novel structures, are presented for the first time. Oligosaccharide A1/2e contains the blood-group-H type-2 antigenic determinant while oligosaccharide A1/2d contains the Lewis(x) determinant.