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Peptide sequence scrambling through cyclization of b(5) ions
1Department of Chemistry, University of Toronto, Toronto, Canada. aharriso@chem.utoronto.ca
Journal of the American Society for Mass Spectrometry
|July 22, 2008
Summary
Collision-induced dissociation (CID) mass spectrometry of hexapeptides reveals that b(5) ions can cyclize, forming nonsequence ions. N-acetylation prevents this cyclization, improving peptide sequence analysis.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Mass Spectrometry
Background:
- Peptide sequencing via mass spectrometry is crucial for proteomics.
- Understanding fragmentation pathways is key to accurate sequence determination.
- Nonsequence ions can complicate peptide analysis.
Purpose of the Study:
- To investigate the fragmentation patterns of hexapeptide isomers using CID mass spectrometry.
- To identify the source of nonsequence ions observed in b(5) ion spectra.
- To evaluate the effect of N-acetylation on peptide fragmentation.
Main Methods:
- Collision-induced dissociation (CID) mass spectrometry was used.
- Analysis of MH(+) and b(5) ions from five hexapeptide isomers.
- Comparison of fragmentation patterns between acetylated and non-acetylated peptides.
Main Results:
- CID mass spectra of b(5) ions from isomers were similar, showing abundant nonsequence ions.
- Nonsequence ions result from the cyclization of b(5) ions to cyclic pentapeptides.
- N-acetylation of the N-terminus prevented b(5) ion cyclization and nonsequence ion formation.
Conclusions:
- Hexapeptide b(5) ions undergo cyclization, leading to nonsequence ions in CID mass spectra.
- N-acetylation effectively suppresses b(5) ion cyclization, simplifying peptide fragmentation analysis.
- This finding aids in the development of more accurate peptide sequencing strategies.
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