Fig. 1.

Schematic representation of common one-pot in-solution linkage-specific derivatization approaches for sialylated glycoconjugates. In the first step, α2,3-linked sialic acids form a lactone with the subterminal galactose, while α2,6-linked sialic acids are subjected to ethyl esterification or Me₂NH (dimethylamine) amidation. In the second step, the lactone undergoes mainly direct aminolysis by NH₃ (ammonia) or MeNH₂ (methylamine), and the α2,6-sialyllactose derivative remains unchanged