- Cell surface glycan
- Applications: decoy glycan for the development of antivirals and antibacterial agents
3′-Sialyl N-acetyl-D-lactosamine (3′-sialyllactosamine or 3′-SL) is a trisaccharide consisting of N-acetylneuraminic acid (sialic acid) linked α2,3 to the galactose residue of N-acetyllactosamine (LacNAc). This structure represents one of the two major forms of sialylated LacNAc found in mammalian glycoconjugates, the other being 6′-sialyl LacNAc where the sialic acid is attached at the C6 position of galactose via an α2,6 linkage. The distinction between α2,3 and α2,6 sialylation has profound biological consequences, affecting everything from lectin recognition to pathogen binding.
The biological significance of 3′-sialyl LacNAc extends across multiple domains. It serves as the immediate biosynthetic precursor to sialyl Lewis X, upon addition of α1,3-fucose to the GlcNAc residue, this trisaccharide becomes the tetrasaccharide selectin ligand critical for leukocyte trafficking. Beyond its role as an intermediate, 3′-sialyl LacNAc is itself an important recognition determinant, most notably as a receptor for avian influenza viruses whose hemagglutinins preferentially bind α2,3-linked sialic acids. This receptor specificity is a key determinant of influenza host range and pandemic potential.
