Figure 1.

(A) Cartoon of the intestinal epithelial cell line, where native GM1 is exposed and binds with high affinity to the cholera toxin subunit B (CTB₅). The establishment of H-bonds between the hydroxyl group at position C2 of the terminal galactose of the GM1 oligosaccharide and Asn14 and Asn90 of CTB₅, which are crucial for a successful interaction, has been reported. Crucially, these H-bonds are not formed when the fluorinated-GM1 derivative (F-GM1) is used for binding to the protein. (B) The structures of both native GM1 and F-GM1 are reported, along with their representations drawn using the Symbol Nomenclature for Glycans (SNFG).