Journal of the American Society for Mass Spectrometry

, Volume 20, Issue 9, pp 1603–1616

Gas-phase scrambling of disulfide bonds during matrix-assisted laser desorption/ionization mass spectrometry analysis

Authors

  • Liang Zhao
    • Department of ChemistryUniversity of the Pacific
  • Ruben T. Almaraz
    • Department of Animal ScienceUniversity of California Davis
  • Fan Xiang
    • Shimadzu Biotech Corporation
  • Jerry L. Hedrick
    • Department of Animal ScienceUniversity of California Davis
    • Department of ChemistryUniversity of the Pacific
Articles

DOI: 10.1016/j.jasms.2009.04.021

Cite this article as:
Zhao, L., Almaraz, R.T., Xiang, F. et al. J Am Soc Mass Spectrom (2009) 20: 1603. doi:10.1016/j.jasms.2009.04.021

Abstract

Evidence for photo-induced radical disulfide bond scrambling in the gas phase during matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is described. The phenomenon was observed during the analysis of tryptic peptides from insulin and was confirmed in the determination of disulfide bonds in the rhamnose-binding lectin SEL24K from the Chinook salmon Oncorhynchus tshawytscha. A possible mechanism for this surprising scrambling is proposed. Despite this finding, the disulfide bond pattern in SEL24K was assigned unambiguously by a multi-enzyme digestion strategy in combination with MALDI mass spectrometry. The pattern was found to be symmetrical in the tandem repeat sequence of SEL24K. To the best of our knowledge, this is the first report of disulfide bond scrambling in the gas phase during MALDI-MS analysis. This observation has important ramifications for unambiguous assignment of disulfide bonds.

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Supplementary material

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Copyright information

© American Society for Mass Spectrometry 2009