Structures of sulfated oligosaccharides isolated from the respiratory mucins of a non-secretor (O, Le(a + b -)) patient suffering from chronic bronchitis

Abstract

Mucin glycopeptides were prepared from the respiratory mucus of a non-secretor, chronic bronchitic patient with blood group O, Le(a + b-). Oligosaccharides were released by alkaline borohydride treatment and purified by anion-exchange chromatography, size-exclusion chromatography and high performance anion-exchange chromatography. Structural studies employed 400-MHz 1H-NMR spectroscopy and matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). Nine monosulfated oligosaccharides ranging in size from tetra- to hexasaccharide, were fully characterized in this study. The sulfate group occurs either on the C-3 of a terminal galactose residue or on the C-6 of a N-acetylglucosamine residue. In keeping with the non-secretor status of the patient, no structure with an (alpha 1-2)-linked fucose residue was found. Five of the structures had fucose present in (alpha 1-3)-linkage in the X determinant, while only one oligosaccharide (compound 7b) was seen with fucose (alpha 1-4)-linked in the Le(a) determinant. Eight structures isolated from the mucins of the non-secretor patient had not been found previously in the respiratory mucins; they are listed below.