Study of peptide-sugar non-covalent complexes by infrared atmospheric pressure matrix-assisted laser desorption/ionization

Infrared atmospheric pressure matrix-assisted laser desorption/ionization quadrupole ion trap mass spectrometry was applied to the study of siglec binding to oligosaccharide ligands. Peptides were designed to mimic the binding sites of three members of the siglec family: sialoadhesin, MAG and CD22. These peptides were tested for their ability to complex with their carbohydrate ligands 3′-sialyllactose (3′SL) and 6′-sialyllactose (6′SL). All peptides demonstrated the ability to bind to the carbohydrates, with the peptide representing sialoadhesin maintaining its binding specificity for 3′SL in preference to 6′SL. This technique can be used to study other protein-sugar interactions and can be expanded to create high-throughput screening techniques.