Isolation and structural characterization of five major sialyloligosaccharides and a sialylglycopeptide from normal human urine

Abstract

Five major sialyloligosaccharides and a sialylglycopeptide have been isolated from normal human urine by charcoal adsorption, gel filtration, ion‐exchange chromatography, and paper chromatography. Structural studies including gas‐liquid chromatography of monosaccharide and disaccharide derivatives, methylation analysis, glycosidase treatments, and CrO3 oxidation indicated the following structures for the compounds: 1, NeuAc(α2‐6)Gal(β1‐4)Glc; 2, NeuAc(α2‐6)Gal(β1‐4)GlcNAc; 3, NeuAc(α2‐3)Gal(β1‐4)Glc; 4, NeuAc(α2‐3)Gal(β1‐4)GlcNAc; 5, NeuAc(α2‐3)Gal(β1‐3) [NeuAc(α2‐6)]GalNAc; and 6, NeuAc(α2‐3)Gal(β1‐3) [NeuAc(α2‐6)]GalNAc(α1‐O)Ser. Compounds 4, 5, and 6 have not been described in a free form before. The presence of compound 5 in urine may suggest that it derives from glycoproteins through a catabolic pathway involving cleavage of the carbohydrate‐peptide linkage by an endo‐N‐acetylgalactosaminidase. The predominating sialyloligosaccharides in urine were compounds 3 and 4. The predominance of the compounds with the sialyl(α2‐3) linkage is of interest in view of the recent discovery of uropathogenic Escherichia coli strains with binding specificity for sialyl(α2‐3)galactosides. Copyright © 1983, Wiley Blackwell. All rights reserved