COLLISIONAL-ACTIVATION TANDEM MASS-SPECTROMETRY OF SODIUM ADDUCT IONS OF METHYLATED OLIGOSACCHARIDES - SEQUENCE-ANALYSIS AND DISCRIMINATION BETWEEN ALPHA-NEUAC-(2-]3) AND ALPHA-NEUAC-(2-]6) LINKAGES

Collision-activated dissociation (c.a.d.) of sodium adducts of molecular ion species have been carried out on methylated beta-D-Galp-(1 half-arrow-pointing-right 4)-beta-D-GlcpNAc-(1 --> 3)-beta-D-Galp-(1 --> 4)-D-Glcp (1), beta-D-Galp-(1 --> 3)-beta-D-GlcpNAc-(1 --> 3)-beta-D-Galp-(1 --> 4)-D-Glcp (2), alpha-D-NeuAc-(2 --> 3)-beta-D-Galp-(1 --> 3)-beta-D-GlcpNAc-(1 --> 3)-beta-D-Galp-(1 --> 4)-D-Glcp (3), alpha-D-NeuAc-(2 --> 6)-beta-D-Galp-(1 --> 4)-beta-D-GlcpNAc-(1 --> 3)-beta-D-Galp-(1 --> 4)-D-Glcp (4), and alpha-D-NeuAc-(2 --> 6)-beta-D-Galp-(1 --> 4)-beta-D-GlcpNAc-(1 --> 2)-alpha-D-Manp-(1 --> 3)-beta-D-Manp-(1 --> 4)-D-GlcpNAc (5). The numerous daughter ions reflect the sequences, clearly differentiate (1 --> 3) and (1 --> 4) linkages, and discriminate between alpha-NeuAc-(2 --> 3) and alpha-NeuAc-(2 --> 6) linkages.