NEGATIVE-ION FAST-ATOM-BOMBARDMENT AND ELECTROSPRAY-IONIZATION TANDEMMASS-SPECTROMETRY FOR CHARACTERIZATION OF SULFATED AND SIALYL LEWIS-TYPE GLYCOSPHINGOLIPIDS

Structural characterization of sulfated and sialyl Lewis (Le)-type gly cosphingolipids performed by fast atom bombardment (FAB) and electrosp ray ionization (ESI) mass spectrometry is described. Both FAB and ESI collision-induced dissociation tandem mass spectrometry (CID-MS/MS) of acidic glycosphingolipids allowed identification of the sulfated or s ialyl sugar, and provided information on the saccharide chain sequence . The negative-ion tandem FABMS of sulfated Le-type glycosphingolipids having the non-reducing end trisaccharide ion as the precursor can be used to differentiate the Le(a)- and Le(x)-type oligosaccharides. The ESI CID-MS/MS of multiple-charged ions provided even more detailed st ructural information, and some of the useful daughter ions appeared wi th higher m/z values than the precusor because of a lower charge-state . These methodologies can be applied to the structural analyses of gly coconjugates with much larger molecular masses and higher polarity, su ch as the poly-sulfated and sialyl analogues.