Chromatograms and Mass Spectra of High-Mannose and Paucimannose N -Glycans for Rapid Isomeric Identifications.

N -Linked glycosylation is one of the most essential post-translational modifications of proteins. However, N -glycan structural determination remains challenging because of the small differences in structures between isomers. In this study, we constructed a database containing collision-induced dissociation MS n mass spectra and chromatograms of high-performance liquid chromatography for the rapid identification of high-mannose and paucimannose N -glycan isomers. These N -glycans include isomers by breaking of arbitrary numbers of glycosidic bonds at arbitrary positions of canonical Man 9 GlcNAc 2 N -glycans. In addition, some GlcMan n GlcNAc 2 N -glycan isomers were included in the database. This database is particularly useful for the identification of the N -glycans not in conventional N -glycan standards. This study demonstrated the application of the database to structural assignment for high-mannose N -glycans extracted from bovine whey proteins, soybean proteins, human mammary epithelial cells, and human breast carcinoma cells. We found many N -glycans that are not expected to be generated by conventional biosynthetic pathways of multicellular eukaryotes.