STRUCTURAL-ANALYSIS OF MONO-SULFATED AND BIS-SULFATED GLYCOSPHINGOLIPIDS BY NEGATIVE LIQUID SECONDARY-ION MASS-SPECTROMETRY WITH HIGH-ENERGY AND LOW-ENERGY COLLISION-INDUCED DISSOCIATION

Several underivatized mono- and bis-sulfated glycosphingolipids having gangliotriaose or gangliotetraose core structure were analyzed by neg ative liquid secondary ion mass spectrometry (LSIMS) with high- and lo w-energy collision-induced dissociation (CID). In the normal negative LSIMS spectra, each mono-sulfated glycolipid gave abundant [M - H](-) ions and each bis-sulfated glycolipid gave abundant [M + Na - 2H](-) i ons as well as the hydrogen sulfate anion [OSO3H](-). In high-energy C ID spectra of the deprotonated molecule, only ions containing a sulfat e ester were clearly observed. When a sulfate was present on the non-r educing terminal saccharide residue, a series of ions corresponding to sulfated mono- to tetra-saccharides, resulting from sequential cleava ge of glycosidic bonds, were observed. If the sulfate was attached to an internal hexose of the sugar chain, the product ions corresponding to the non-sulfated, non-reducing terminal residue were absent. In con trast, the low-energy CID resulted in extremely simple spectra that co ntained