N-Glycopedia: Libraries for Native N-glycan Structural Analysis

Studies on N-glycans of human glycoproteins are hampered by the lack of standards that reflect the wide diversity in composition and branching typically observed. To this end we have exploited a large library of N-glycan standards comprised of a unique collection of 226 N-glycans including oligomannose, hybrid, and complex-type. We generated a method employing porous graphitized carbon (PGC) and liquid chromatography mass spectrometry (PGC-LC-MS), which can provide a high degree of resolution of underivatized N-glycans as well as separation of structural isomers. Chromatogram libraries arising from these studies include retention time data, diagnostic fragment ions, and validated structural assignments, providing a robust platform for both targeted and discovery-based glycomics. We refer to this as an N-glycopedia, the first type of resource in which researchers can compare this collective data to N-glycans under study from natural sources and overcome the limitations of only having compositional data and predicted structures. The technology is easily expandable to include additional N-glycans as new standards become available.