Research Article

Journal of The American Society for Mass Spectrometry

, Volume 23, Issue 2, pp 310-320

First online:

Electron Transfer Dissociation (ETD) of Peptides Containing Intrachain Disulfide Bonds

  • Scott R. ColeAffiliated withDepartment of Chemistry, Purdue University
  • , Xiaoxiao MaAffiliated withDepartment of Chemistry, Tsinghua University
  • , Xinrong ZhangAffiliated withDepartment of Chemistry, Tsinghua University
  • , Yu XiaAffiliated withDepartment of Chemistry, Purdue University Email author 


The fragmentation chemistry of peptides containing intrachain disulfide bonds was investigated under electron transfer dissociation (ETD) conditions. Fragments within the cyclic region of the peptide backbone due to intrachain disulfide bond formation were observed, including: c (odd electron), z (even electron), c-33 Da, z + 33 Da, c + 32 Da, and z–32 Da types of ions. The presence of these ions indicated cleavages both at the disulfide bond and the N–Cα backbone from a single electron transfer event. Mechanistic studies supported a mechanism whereby the N–Cα bond was cleaved first, and radical-driven reactions caused cleavage at either an S–S bond or an S–C bond within cysteinyl residues. Direct ETD at the disulfide linkage was also observed, correlating with signature loss of 33 Da (SH) from the charge-reduced peptide ions. Initial ETD cleavage at the disulfide bond was found to be promoted amongst peptides ions of lower charge states, while backbone fragmentation was more abundant for higher charge states. The capability of inducing both backbone and disulfide bond cleavages from ETD could be particularly useful for sequencing peptides containing intact intrachain disulfide bonds. ETD of the 13 peptides studied herein all showed substantial sequence coverage, accounting for 75%–100% of possible backbone fragmentation.

Key words

Disulfide bond Electron transfer dissociation Post-translational modification Peptide sequencing Mass spectrometry