3P-23 PDF
Sialyl linkage-specific glycan profiling using solid-phase SALSA
Recently, we have developed Sialic Acid Linkage-Specific Alkylamidation (SALSA) for linkage isomer discrimination of sialic acid residues on glycans. SALSA stabilizes the residues by converting α2,6-linked sialic acids to their isopropylamine-derivatized forms, whereas α2,3-linked sialic acids to methylamine-derivatized forms, allowing direct discrimination of sialyl linkages based on the difference in m/z values. To facilitate derivatization reaction and following purification steps, two types of solid-phase SALSA reaction were investigated: glycan-level and glycoprotein-level. In the glycan-level approach, glycans released from glycoproteins were captured by hydrazide beads, and then SALSA reaction was performed. Derivatized glycans were released from the beads by acid treatment. In the glycoprotein-level approach, glycoproteins were directly attached to protein immobilization beads. After SALSA reaction, derivatized N-glycans were released by PNGaseF digestion. Resultant amide bonds formed by SALSA reactions are fully stable and, consequently, glycan labelings could be performed after the reaction without producing any by-products. We believe that this solid-phase amidation for sialic acid residues has greater versatility than existing linkage-specific esterification approaches in the combination with other glycan analysis approaches.