Sialylation and sulfation of the carbohydrate chains in respiratory mucins from a patient with cystic fibrosis

Abstract

Mucin glycopeptides were prepared from the sputum of a patient suffering from cystic fibrosis. The carbohydrate chains were released by alkaline borohydride treatment. Sialylated and sulfated oligosaccharide-alditols were purified by ion-exchange chromatography, gel filtration, and high performance anion-exchange chromatography. The structures of the oligosaccharide-alditols were determined by high resolution 1H NMR spectroscopy in combination with fast atom bombardment-mass spectrometry. Twenty-four oligosaccharides were characterized and illustrate the diversity of the carbohydrate chains of cystic fibrosis respiratory mucins. Among these 24 oligosaccharide-alditols, 15 are novel structures. Sialylation may occur on the C-6 of the N-acetylgalactosamine involved in the carbohydrate-peptide linkage or on a terminal galactose residue, either on C-3 or on C-6. Sulfation may occur either on the C-3 of a terminal galactose residue or on the C-6 of a N-acetylglucosamine residue. The most complex structures contain sulfated derivatives of the H,X, or Y determinants or a sialylated and sulfated derivative of the X determinant (Structure A).