Fig. 2.

Representative MALDI-TOF-MS spectra showing the modifications induced on an α2,3-sialyllactitol standard under native reaction conditions in EtOH (a-c) or DMSO (d-f). Symbols indicate the monosaccharide residues glucose (blue circle), galactose (yellow circle) and N-acetylneuraminic acid (purple diamond). In case of derivatized sialic acids, an α2,3-linkage is depicted with a left angle, with lactonization indicated by L, NH₃ amidation by AA, MeNH₂ amidation by MA, and Me₂NH amidation by DA next to the sialic acid residue. Non-derivatized sialic acids are depicted without an angle. All species were detected as [M + Na]⁺