Evaluation of low energy CID and ECD fragmentation behavior of mono-oxidized thio-ether bonds in peptides

  • Saiful M. Chowdhury
  • Gerhard R. Munske
  • Robert C. Ronald
  • James E. Bruce
Articles

DOI: 10.1016/j.jasms.2006.10.019

Cite this article as:
Chowdhury, S.M., Munske, G.R., Ronald, R.C. et al. J Am Soc Mass Spectrom (2007) 18: 493. doi:10.1016/j.jasms.2006.10.019

Abstract

Thio-ether bonds in the cysteinyl side chain of peptides, formed with the most commonly used cysteine blocking reagent iodoacetamide, after conversion to sulfoxide, releases a neutral fragment mass in a low-energy MS/MS experiment in the gas phase of the mass spectrometer [6]. In this study, we show that the neutral loss fragments produced from the mono-oxidized thio-ether bonds (sulfoxide) in peptides, formed by alkyl halide or double-bond containing cysteine blocking reagents are different under low-energy MS/MS conditions. We have evaluated the low-energy fragmentation patterns of mono-oxidized modified peptides with different cysteine blocking reagents, such as iodoacetamide, 3-maleimidopropionic acid, and 4-vinylpyridine using FTICR-MS. We propose that the mechanisms of gas-phase fragmentation of mono-oxidized thio-ether bonds in the side chain of peptides, formed by iodoacetamide and double-bond containing cysteine blocking reagents, maleimide and vinylpyridine, are different because of the availability of acidic β-hydrogens in these compounds. Moreover, we investigated the fragmentation characteristics of mono-oxidized thio-ether bonds within the peptide sequence to develop novel mass-spectrometry identifiable chemical cross-linkers. This methionine type of oxidized thio-ether bond within the peptide sequence did not show anticipated low-energy fragmentation. Electron capture dissociation (ECD) of the side chain thio-ether bond containing oxidized peptides was also studied. ECD spectra of the oxidized peptides showed a greater extent of peptide backbone cleavage, compared with CID spectra. This fragmentation information is critical to researchers for accurate data analysis of this undesired modification in proteomics research, as well as other methods that may utilize sulfoxide derivatives.

Supplementary material

13361_2011_180300493_MOESM1_ESM.rtf (540 kb)
Supplementary material, approximately 553 KB.

Copyright information

© American Society for Mass Spectrometry 2007

Authors and Affiliations

  • Saiful M. Chowdhury
    • 1
  • Gerhard R. Munske
    • 1
  • Robert C. Ronald
    • 1
  • James E. Bruce
    • 1
  1. 1.Department of ChemistryWashington State UniversityPullmanUSA

Personalised recommendations