A novel neutral oligosaccharide chain found in polysialoglycoproteins isolated from Pacific salmon eggs. Structural studies by secondary ion mass spectrometry, proton nuclear magnetic resonance spectroscopy, and chemical methods.

A novel carbohydrate chain possessing a hitherto unknown disaccharide unit, alpha-L-Fuc leads to D-GalNAc, has been isolated from salmon egg polysialoglycoproteins on alkali-borohydride treatment. Salmon egg polysialoglycoproteins contain O-glycosidically linked neutral pentasaccharide chains in addition to a number of oligosialosyl group containing sugar chains. Composition analysis of the neutral pentasaccharide gave fucose, galactose, 2-acetamido-2-deoxygalactose, and 2-acetamido-2-deoxygalactitol in a molar ratio of 1:2:1:1. The structure was determined to be alpha-L-Fuc(1 leads to 3)-beta-D-GalNAc-(1 leads to 3)-beta-D-Gal(1 leads to 4)-beta-D-Gal(1 leads to 3)-D-GalNAcol by the following three major procedures: First, the sequential order of the constitutional monosaccharides was determined by secondary ion mass spectrometry before and after permethylation. Second, linkages were established by methylation analysis and Smith degradation and hydrazinolysis-nitrous deamination studies. Third, anomeric configuration of the glycosidic linkages involved was deduced from 270-MHz proton nuclear magnetic resonance spectroscopy.