Primary structure determination of five sialylated oligosaccharides derived from bronchial mucus glycoproteins of patients suffering from cystic fibrosis. The occurrence of the NeuAc alpha(2----3)Gal beta(1----4)[Fuc alpha(1----3)] GlcNAc beta(1----.) structural element revealed by 500-MHz 1H NMR spectroscopy.

G Lamblin,A Boersma,A Klein,P Roussel,H Van Halbeek,J F Vliegenthart

doi:10.1016/s0021-9258(17)47263-2

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, NeuAc alpha(2----3)Gal beta(1----4) [Fuc alpha(1----3)]GlcNAc beta(1----3)Gal-NAc-ol; A-2, NeuAc alpha(2----3)Gal beta(1----4)GlcNAc beta(1----6)-[GlcNAc beta (1----3)]GalNAc-o1; A-3, NeuAc alpha(2----3)Gal beta-(1----4)[Fuc alpha(1----3)]GlcNAc beta(1----3)Gal beta(1----3) GalNAc-o1; A-4, NeuAc alpha(2----3)Gal beta(1----4)[Fuc alpha(1----3)]Glc-NAc NAc beta(1----6)[GlcNAc beta(1----3)]GalNAc-o1; A-6,NeuAc alpha-(2----3) Gal beta(1----4)[Fuc alpha(1----3)]GlcNAc beta(1----6)[Gal beta-(1----4) GlcNAc beta(1----3)]GalNAc-o1. The simultaneous presence of sialic acid in alpha(2----3)-linkage to Gal and fucose in alpha(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.

Highlights

Thestructureof sialylated carbohydrate units of isolated from sputum of patients suffering from bronchial bronchial mucins obtained frocmystic fibrosis patients hypersecretion ( 2, 3)
After subjecting the hydrate chains, substantial amounts of these oligosaccharides mucinsto alkalineborohydride degradationsi,alylated have beenisolated by us from the sputum of six patients with oligosaccharide-alditols wereisolatedby anion-ex- blood group0,who suffered from cystic fibrosi(s4).Here, we change chromatography and fractionated by high perre-port the fractionation and thepurification by hplcl of these formanceliquidchromatography
Thsiemultaneous presence of sialic acid in a(2-+3)-linkage to Gal and fucose in a(ld3)-linkage to GlcNAc of the same N

Summary

DISCUSSION

Presence of sialic acid in a(2-+3)-linkage to Gal and fucose in a(ld3)-linkage to GlcNAc of the same N-. The structures of 15 neutral oligosaccharides present in fraction ICobtained from purified bronchial acidic glycoproteins secreted by six patients suffering from cystic fibrosis have already been reported [3].The corresponding sialic acidrich fractionIIcrepresents 7% (by weight) of the various fractions recovered after alkaline borohydride treatment (fraction IC represented 16.8%).It was subfractionated into two main peaks (see Fig. I). For all investigated sialylated bronchial oligosaccharidealditols, NeuAc wasfound to be a(2+3)-linked to Gal forming part of an N-acetyllactosamine moiety This is remarkable, since most of the sialylated oligosaccharides stemming from mucins that hadbeen characterized until now contain NeuAc or NeuGc in cr[24]-linkage to GalNAc(-ol) [16,17,18,19,20].

TABLE I

Sialylated OligosaccharidesfromBronchial Mucins