Combined partial acid hydrolysis and electrospray ionization-mass spectrometry for the structural determination of oligosaccharides

A general oligosaccharide acid hydrolysis method, amenable to electrospray ionization mass spectrometry (ESI-MS), is described that allows for hydroly sis of glycosidic bonds for both hexose- and N-acetylhexosamine-containing oligosaccharides. The partial acid hydrolysis of oligosaccharides is obtain ed by using an acid-exchange resin as the acid catalyst. A ladder sequence of the glycan is produced in solution that is directly analyzed by ESI tand em mass spectrometry, employing both ion trap and Fourier transform ion cyc lotron resonance mass spectrometers, to provide sequence and linkage inform ation. Unlike traditional acid hydrolysis procedures, there is minimal degr adation of monosaccharide residues or deacetylation of N-acetylhexosamines by employing this technique. It is further demonstrated that the stereochem istry of the released monosaccharides and the anomeric configuration within disaccharides is determined by direct derivatization of the hydrolysate wi th Zn(dien)-Cl-2 followed by ESI-MS/MS.