Fig. 4.

Comparative MALDI-MS mapping of the neutral PA-glycans derived from GEW (A), GOM (B), and GOT (C). All major molecular ion signals afforded by the permethylated samples were monosodiated and the assigned structures, as deduced from both composition and MS/MS data, were annotated along with their monoisotopic m/z values. The mass regions from m/z 3000 to m/z 3800 were additionally magnified and presented as offsets above the main spectral traces. Satellite peaks at 76 mass units below that of major signals, most notably m/z 2535, are marked with an asterisk and correspond to non-PA tagged, but reduced and similarly permethylated glycans. Symbols used conform to the recommendations of the Consortium for Functional Glycomics, but the orange spheres represent α-Gal.