Beyond quantitative proteomics: Signal enhancement of the a1 ion as a mass tag for peptide sequencing using dimethyl labeling

Jue Liang Hsu, Sheng Yu Huang, Jen Taie Shiea, Wen Ying Huang, Shu-Hui Chen

Research output: Contribution to journalArticlepeer-review

102 Citations (Scopus)


Stable isotope-based dimethyl labeling that produces a dimethyl labeled terminal amine or a monomethylated proline N-terminus by reductive methylation (Anal. Chem. 2003, 75, 6843-6852) was reported as a promising strategy for global quantitative proteomics because of the simplicity of the process and its fast and complete reaction. This labeling strategy provides a signal enhancement for the produced a1 ions, which are usually hard to detect among most of the nonderivatized fragments. To assist peptide sequencing, in this study, the enhanced a1 ion produced under either collision induced dissociation (CID) or post source decay (PSD) modes was further characterized and applied as a mass tag for fingerprinting the identity of N-terminal amino acid. On the basis of the analysis of standard peptides, tryptic digests of hemoglobin and cell lysates, it was proved that such signal enhancement occurred to a1 ions derived from all 20 of the amino acids residues and this phenomenon was explained based the formation of stable quaternary immoniun ions. Accurate determination of a1 ions was shown to increase the chance for peptide de novo sequencing and also provided higher confidence in the scores obtained when identifying a protein through database searching. In addition, the a1 ion was further demonstrated to be used as a universal tag for precursor ion scan in a Q-TOF instrument, leading to a greater number of peptide ions sequenced. Combined with the capability for differential quantitation, the stable isotope-based dimethyl labeling increases the usefulness of the labeling method for MS-based proteomics.

Original languageEnglish
Pages (from-to)101-108
Number of pages8
JournalJournal of Proteome Research
Issue number1
Publication statusPublished - 2005 Jan 1

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Chemistry(all)


Dive into the research topics of 'Beyond quantitative proteomics: Signal enhancement of the a<sub>1</sub> ion as a mass tag for peptide sequencing using dimethyl labeling'. Together they form a unique fingerprint.

Cite this