title: Localization of O-glycosylation sites of MUC1 tandem repeats by QTOF ESI mass spectrometry.
abstract: The potential of electrospray mass spectrometry (ESMS) for the sequencing of glycopeptides was evaluated using quadrupole time-of-flight (QTOF) technology in the MS/MS mode. The location of O-glycosylation sites was possible in the positive ion (+) mode by detection of prominent y- and b-fragment ions from the underivatized TAP25-2 [T1APPAHGVT9S10APDT14RPAPGS20T21APPA], an overlapping sequence of MUC1 tandem repeats which had been glycosylated in vitro by two GalNAc residues in the positions T9 and T21. The high mass resolution and accuracy of QTOF-(+)ESMS allowed reliable structural assignments. The reduced complexity of the fragment spectra and the higher signal-to-noise ratio render QTOF-(+)ESMS an alternative mass spectrometric approach to the identification of O-glycosylation sites when compared with sequencing by post-source decay matrix-assisted laser desorption/ionization MS. Diagnostic ions from the N-terminus in the b-series offered direct evidence, which was supported by indirect evidence from the C-terminus ions of the y-series. The higher glycosylated GalNAc2-substituted fragments were mainly observed as multiply ionized species.
authors.affiliation: Institut für Biochemie, Universität Köln, Germany.
authors.forename: F G
authors.initials: FG
authors.lastname: Hanisch
authors.forename: B N
authors.initials: BN
authors.lastname: Green
authors.forename: R
authors.initials: R
authors.lastname: Bateman
authors.forename: J
authors.initials: J
authors.lastname: Peter-Katalinic
mesh_terms: D000595:Amino Acid Sequence; D006031:Glycosylation; D008969:Molecular Sequence Data; D018396:Mucin-1 / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D018629:Spectrometry, Mass, Secondary Ion
chemical_list: D018396:Mucin-1