α-Cyano-3-aminocinnamic acid: A novel reactive matrix for qualitative and quantitative analysis of plant N-glycans by...

N-glycans have a diversity of crucial biological roles in organisms. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has become an indispensable analytical instrument for biomolecules. However, due to the inherent low abundance, high structural heterogeneity, and poor ionization efficiency of N-glycans, as well as the extremely inhomogeneous co-crystal property using traditional matrices, the qualitation and quantitation of N-glycans by MALDI-MS remains challenging. In the present study, α-cyano-3-aminocinnamic acid (3-CACA) was reasonably designed and synthesized as a novel reactive matrix for N-glycan analysis. Combining with traditional matrix α-cyano-4-hydroxycinnamic acid (CHCA) as an acidic catalyst, a combinational matrix 3-CACA/CHCA was obtained with homogeneous co-crystallization and high derivatization efficiency, achieving the sensitive qualitation with the limits of detection low to femtomole and reproducible quantitation with good linearity (R² > 0.998). As a result, the established method was successfully applied to the on-target derivatization and high-throughput quantification of N-glycans in eight varieties of the peach complex system, indicating that N-glycan has the potential to become a new biomarker for food allergy, and elucidating the prospective correlation between N-glycan epitopes and allergic reactions.