Analysis of N- and O-glycosidically bound sialooligosaccharides in glycoproteins by high-performance liquid chromatography with pulsed amperometric detection.

N-Glycosidically bound sialooligosaccharides in a model glycoprotein of serum type (porcine thyroglobulin) were released by pronase digestion, followed by hydrazinolysis. The resulting oligosaccharides were re-N-acetylated and reduced with sodium borohydride. On the other hand, O-glycosidically bound sialooligosaccharides were released from a mucin-type glycoprotein (bovine submaxillary mucin) with alkali in the presence of sodium borohydride. The reduced oligosaccharides thus obtained from both types of glycoproteins were analysed by high-performance liquid chromatography on a column of a latex-type pellicular anion-exchange resin with strong alkali as eluent. These sequential procedures were useful for mapping of oligosaccharides in glycoproteins.