Improved Sequencing of Oxidized Cysteine and Methionine Containing Peptides Using Electron Transfer Dissociation

R. Srikanth, Jonathan Wilson, Juma D. Bridgewater, Jason R. Numbers, Jihyeon Lim, Mark R. Olbris, Ali Kettani, Richard W. Vachet

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


Oxidative modifications to the side chains of sulfur-containing amino acids often limit the number of product ions formed during collision-induced dissociation (CID) and thus make it difficult to obtain sequence information for oxidized peptides. In this work, we demonstrate that electron-transfer dissociation (ETD) can be used to improve the sequence information obtained from peptides with oxidized cysteine and methionine residues. In contrast to CID, ETD is found to be much less sensitive to the side-chain chemistry, enabling extensive sequence information to be obtained in cases where CID fails to provide this information. These results indicate that ETD is a valuable technique for studying oxidatively modified peptides and proteins. In addition, we report a unique and very abundant product ion that is formed in the CID spectra of peptides having N-terminal cysteine sulfinic acid residues. The mechanism for this unique dissociation pathway involves a six-membered cyclic intermediate and leads to the facile loss of NH3 and SO2, which corresponds to a mass loss of 81 Da. While the facile nature of this dissociation pathway limits the sequence information present in CID spectra of peptides with N-terminal cysteine sulfinic acid residues, extensive sequence information for these peptides can be obtained with ETD.

Original languageEnglish (US)
Pages (from-to)1499-1506
Number of pages8
JournalJournal of the American Society for Mass Spectrometry
Issue number8
StatePublished - Aug 2007
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy


Dive into the research topics of 'Improved Sequencing of Oxidized Cysteine and Methionine Containing Peptides Using Electron Transfer Dissociation'. Together they form a unique fingerprint.

Cite this