title: Structural assignment of isomeric 2-aminopyridine-derivatized oligosaccharides using negative-ion MSn spectral matching.
abstract: To investigate the possibility of structural assignment based on negative-ion MS2 spectral matching, three isomeric pairs of 2-aminopyridine (PA)-derivatized non-fucosylated, fucosylated, and sialylated oligosaccharides (complex type N-glycans) were analyzed using high-performance liquid chromatography/ion trap mass spectrometry (HPLC/ITMS) with a sonic-spray ionization (SSI) source. In the SSI negative-ion mode the deprotonated molecule [M-2H]2- becomes prominent. Negative-ion MS2 spectra derived from such ions contain many fragment types (B and Y, C and Z, A, and D) and therefore are more informative than the positive-ion MS2 spectra derived from [M+H+Na]2+ ions, which usually consist mainly of B and Y fragment ions. In particular the internal ions (D- and E-type ions) provided useful information about the alpha1-6 branching patterns and the bisecting GlcNAc residue. Spectral matching based on the correlation coefficients between negative-ion MS2 spectra was performed in a manner similar to the positive-ion MS2 spectral matching previously reported. It was demonstrated that negative-ion MS2 spectral matching is as useful and applicable to the structural assignment of relatively large non-fucosylated, fucosylated, and sialylated PA-oligosaccharide isomers as its positive-ion counterpart.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 001-0021, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takegawa
authors.forename: Kisaburo
authors.initials: K
authors.lastname: Deguchi
authors.forename: Shinya
authors.initials: S
authors.lastname: Ito
authors.forename: Shinji
authors.initials: S
authors.lastname: Yoshioka
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Nishimura
mesh_terms: D000631:Aminopyridines / Q000737:chemistry* / Q000145:classification; D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007536:Isomerism; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry* / Q000145:classification; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D000631:Aminopyridines; D009844:Oligosaccharides; C032439:alpha-aminopyridine