Characterization of O-glycosylation sites in MUC2 glycopeptides by nanoelectrospray QTOF mass spectrometry

Sequencing of eight O-glycosylated peptides by nanoESI-QTOF-MS/MS was carri ed out to provide a sensitive general characterization method for determina tion of glycosylation site(s) and of the type of the attached carbohydrate moiety in a single experiment. The glycopeptide structures were chosen to d emonstrate the feasibility of this sensitive and accurate approach, where i sobaric peptide structures either (i) with the same number of attachment si tes in different position in the peptide backbone, and (ii) with the same n umber of sugar moieties distributed on different attachment sites in the pe ptide backbone, can be clearly distinguished. Beside the B-type carbohydrat e sequence ions of high abundance, it is possible to register diagnostic b- and y-type glycosylated peptide ions of lower abundance due to high dynami c range of the QTOF analyser. The applicability of this approach for detail ed analysis of highly clustered O-glycan structures as found in biological mucin samples is discussed. Copyright (C) 1999 John Wiley & Sons Ltd.