Journal of the American Society for Mass Spectrometry

, Volume 16, Issue 9, pp 1493–1497

Evidence for unfolding and refolding of gas-phase cytochrome c ions in a Paul trap


  • Ethan R. Badman
    • Department of ChemistryIndiana University
  • Sunnie Myung
    • Department of ChemistryIndiana University
    • Department of ChemistryIndiana University
Short Communication

DOI: 10.1016/j.jasms.2005.04.013

Cite this article as:
Badman, E.R., Myung, S. & Clemmer, D.E. J Am Soc Mass Spectrom (2005) 16: 1493. doi:10.1016/j.jasms.2005.04.013


The folding pathways of gas-phase cytochrome c ions produced by electrospray ionization have been studied by an ion trapping/ion mobility technique that allows conformations to be examined over extended timescales (10 ms to 10 s). The results show that the +9 charge state emerges from solution as a compact structure and then rapidly unfolds into several substantially more open structures, a transition that requires 30–60 ms; over substantially longer timescales (250 ms to 10 s) elongated states appear to refold into an array of folded structures. The new folded states are less compact than those that are apparent during the initial unfolding. Apparently, unfolding to highly open conformations is a key step that must occur before +9 ions can sample more compact states that are stable at longer times.

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© American Society for Mass Spectrometry 2005