PMID: 9597769

 

    Legend: Sugar

Title : Localization of O-glycosylation sites of MUC1 tandem repeats by QTOF ESI mass spectrometry

Abstract :

1. 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
2. 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
3. The high mass resolution and accuracy of QTOF-(+)ESMS allowed reliable structural assignments
4. 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
5. The higher glycosylated GalNAc2-substituted fragments were mainly observed as multiply ionized species