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

Abstract
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 © 2004 John Wiley & Sons, Ltd.