SEPARATION AND CHARACTERIZATION OF O-DEACYLATED LIPOOLIGOSACCHARIDES AND GLYCANS DERIVED FROM MORAXELLA-CATARRHALIS USING CAPILLARY ELECTROPHORESIS ELECTROSPRAY MASS-SPECTROMETRY AND TANDEM MASS-SPECTROMETRY

Electrophoretic methods have been developed for the analysis of comple x carbohydrates derived from lipooligosaccharides (LOS) of Moraxella c atarrhalis using capillary electrophoresis coupled to electrospray mas s spectrometry (CE-ESMS). Separation of lipooligosaccharides (LOS) ari sing from mild hydrazinolysis of the intact lipopolysaccharides (LPS) was achieved using aqueous ammonium formate, and enabled identificatio n of sites of heterogeneity (phosphates, phosphoethanolamine, and pend ant acyl groups) on either the lipid A or the core oligosaccharide, Mo re complex mixtures of carbohydrates obtained from the complete deacyl ation and dephosphorylation of LOS were amenable to electrophoretic co nditions using both anionic and cationic separation, In particular, el ectrophoretic conditions were developed which permitted resolution of closely related oligosaccharides according to the number of carbohydra te residues appended to the core structure, Structural characterizatio n of carbohydrates and LOS released from the hydrazinolysis and acid h ydrolysis treatment of the intact LPS was achieved using tandem mass s pectrometry (MS-MS) for samples introduced by direct flow injection. T aken together, the combination of CE-ESI-MS and MS-MS analyses provide d valuable information on the heterogeneity of the LOS population in w hich a significant level of variability was found mostly in the lipid A portion.