A Method to Enhance a1 Ions and Application for Peptide Sequencing and Protein Identification

Ning Liu, Wan Chan, Kim-Chung Lee, Zongwei Cai*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

9 Citations (Scopus)


A simple and effective method was developed for peptide sequencing and protein identification through the determination of its N-terminal residue. The method of N-terminal carbamidomethylation with iodoacetamide could specifically and remarkably enhance the intensity of a1 ions in the tandem mass spectra of the peptide derivatives without significantly altering their fragmentation pattern, thus allowing determination of their N-terminal residues. The effectiveness and specificity of the method was demonstrated by confirming and extending sequence interpretation of several model peptides and proteins. The developed method was then applied in the LC-MS/MS analysis of the tryptic digests of myoglobin and a whole protein extract from rat heart tissues. The results from database searches were well validated with the enhancement of a1 ions in tandem mass spectra and the specificity of protein identification was obtained when the information of N-terminal residues was included in the database search.

Original languageEnglish
Pages (from-to)1214-1223
Number of pages10
JournalJournal of the American Society for Mass Spectrometry
Issue number6
Publication statusPublished - Jun 2009

Scopus Subject Areas

  • Structural Biology
  • Spectroscopy

User-Defined Keywords

  • Octreotide
  • Protein Identification
  • Iodoacetamide
  • Tandem Mass Spectrum
  • Mass Spectrometric Sequencing


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