Gas-Phase Scrambling of Disulfide Bonds during Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Analysis

Liang Zhao, Ruben T. Almaraz, Fan Xiang, Jerry L. Hedrick, Andreas H. Franz

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish (US)
Pages (from-to)1603-1616
Number of pages14
JournalJournal of the American Society for Mass Spectrometry
Volume20
Issue number9
DOIs
StatePublished - Sep 2009
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy

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