Primary structure determination of five sialylated oligosaccharides derived from bronchial- mucus glycoproteins of patients suffering from cystic fibrosis. The occurrence of the NeuAcα(2→3)Galα(1→4)[Fucα(1→3)]GlcNAcα(1→.) structural element revealed by 500-MHz 1H NMR spectroscopy

Abstract

The structure of sialylated carbohydrate units of bronchial mucins obtained from cystic fibrosis patients was investigated by 500-MHz 1H NMR spectroscopy in conjunction with sugar analysis. After subjecting the mucins to alkaline borohydride degradation, sialylated oligosaccharide-alditols were isolated by anion-exchange chromatography and fractionated by high performance liquid chromatography. Five compounds could be obtained in a rather pure state; their structures were established as the following: A-1, NeuAcα(2→3)Galβ(1→4) [Fucα(1→3)]GlcNAcβ(1→3)Gal-NAc-ol; A-2, NeuAcα(2→3)Galβ(1→4)GlcNAcβ(1→6)-[GlcNAcβ(1→3)]GalNAc-o1; A-3, NeuAcα(2→3)Galβ-(1→4)[Fucα(1→3)]GlcNAcβ(1→3)Galβ(1→3) GalNAc-o1; A-4, NeuAcα(2→3)Galβ(1→4)[Fucα(1→3)]Glc-NAc NAcβ(1→6)[GlcNAcβ(1→3)]GalNAc-o1; A-6,NeuAcα-(2→3) Galba(1→4)[Fucα(1→3)]GlcNAcβ(1→6)[Galβ-(1→4) GlcNAcβ(1→3)]GalNAc-o1. The simultaneous presence of sialic acid in α(2→3)- linkage to Gal and fucose in α(1→3)-linkage to GlcNAc of the same N-acetyllactosamine unit could be adequately proved by high resolution 1H NMR spectroscopy. This sequence constitutes a novel structural element for mucins.