LC-MS/MS OF PERMETHYLATED N-GLYCANS DERIVED FROM MODEL AND HUMAN BLOOD SERUM GLYCOPROTEINS

摘要

LC-MS/MS is one of the most powerful tools for N-glycan structure elucidation; however, it is still challenging to identify some glycan structures with low abundance. In this study, we investigated the chromatographic behavior of permethylated N-glycans. The relationship between retention times vs. molecular weight of dextran, dextrin and model glycans was investigated. Also, the non-polar surface area (NPSA) of glycans was calculated and compared to their experimental retention time. The two trends are similar when the intermolecular interaction is included in the calculation. Moreover, the retention time corresponds to glycan types and branch types. The N-glycans analysis model, which combines high mass accuracy and retention time, was applied to confirm serum N-glycans. In total, there were 78 N-glycan compositions identified. A linear relationships between retention times and molecular weights were observed for each subgroup of glycan structures, for example, R² > 0.98 for complex N-glycans. Moreover, the retention time could be further applied to distinguish between structural isomers as well as linkage isomers. MS/MS data was used to confirm the structural isomers.