Structural assignment of isomeric 2-aminopyridine-derivatized oligosaccharides using MSn spectral matching

Two isomeric pairs of 2-aminopyridine (PA)-derivatized fucosylated and non-fucosylated oligosaccharides (complex-type N-glycans of IgG) were analyzed using liquid chromatography/ion trap mass spectrometry (LC/ITMS) with a sonic spray ionization source and by varying the collision-induced dissociation voltage. Reproducibility of MSn (n = 2) spectra obtained by LC/ITMS was tested considering both fragment ions (m/z) and intensities. A comparison of their MSn spectra and evaluation of similarities (or matching), based on correlation coefficients between MSn spectra, was investigated as a possibility for structural assignment of the isomers. It is shown that such MSn spectral matching is useful and applicable to the structural assignment of relatively large fucosylated and sialylated PA-oligosaccharides released from IgG based on Bn- and Yn-type fragmentations of the corresponding [M+H+Na](2+) ions. Copyright (C) 2004 John Wiley Sons, Ltd.