The analysis of multipleO-phosphoseryl-containing peptides by fast atom bombardment mass spectrometry

✍ Scribed by J. W. Perich; Imantz Liepa; Alan L. Chaffee; R. B. Johns

• Publisher: Springer Netherlands
• Year: 1996
• Tongue: English
• Weight: 478 KB
• Volume: 2
• Category: Article
• ISSN: 1573-3149
• DOI: 10.1007/bf00119998

✦ Synopsis

Positive and negative ion FAB mass spectrometry were found to be useful for the structural analysis of phosphorylated peptides containing multiple O-phosphoseryl residues. The positive ion FAB mass spectra obtained for Ac-Ser(P)-Ser(P)-NHMe and Ac-Ser(P)-Ser(P)-Ser(P)-NHMe showed that [3-eliminative loss of H3PO 4 from the Ser(P)-residue was a major event in the fragmentation of the two phosphopeptides and that successive losses of H3PO 4 from the [M+H] ÷ ion occurred when the Ser(P)-cluster was located at the N-terminus. In contrast, the FAB mass spectrum of Ac-Glu-Ser(P)-Leu-Ser(P)-Ser(P)-Ser(P)-Glu-Glu-NHMe showed only a single loss of H3PO 4 from the [M+H] + ion, with further losses of H3PO4 from internal Ser(P)-residues only occurring when fragmentation of the parent phosphopeptide generated daughter fragments that contained (part of) an N-terminal Ser(P)-residue. Negative ion FAB mass spectrometry also proved useful for the structural analysis of the three Ser(P)-peptides and showed high-intensity [M-HI-ions along with minor [M-H-80]-and [M-H-98]-}'ragment ions.