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Article
Effect of protein stabilization on charge state distribution in positive- and negative ion electrospray ionization mass spectra
Faculty of Science - Papers (Archive)
  • Stephen J. Watt, University of Wollongong
  • Margaret Sheil, University of Wollongong
  • Jennifer L Beck, University of Wollongong
  • Pavel Prosselkov, Australian National University
  • Gottfried Otting, Australian National University
  • Nicholas E Dixon, University of Wollongong
RIS ID
20927
Publication Date
1-1-2007
Publication Details

Watt, S., Sheil, M., Beck, J. L., Prosselkov, P., Otting, G. & Dixon, N. E. (2007). Effect of protein stabilization on charge state distribution in positive- and negative ion electrospray ionization mass spectra. Journal of the American Society for Mass Spectrometry, 18 (9), 1605-1611.

Abstract

Changes in protein conformation are thought to alter charge state distributions observed in electrospray ionization mass spectra (ESI-MS) of proteins. In most cases, this has been demonstrated by unfolding proteins through acidification of the solution. This methodology changes the properties of the solvent so that changes in the ESI-MS charge envelopes from conformational changes are difficult to separate from the effects of changing solvent on the ionization process. A novel strategy is presented enabling comparison of ESI mass spectra of a folded and partially unfolded protein of the same amino acid sequence subjected to the same experimental protocols and conditions. The N-terminal domain of the Escherichia coli DnaB protein was cyclized by in vivo formation of an amide bond between its N- and C-termini. The properties of this stabilized protein were compared with its linear counterpart. When the linear form was unfolded by decreasing pH, a charge envelope at lower m/z appeared consistent with the presence of a population of unfolded protein. This was observed in positive ion and negative ion ESI mass spectra. Under the same conditions, this low m/z envelope was not present in the ESI mass spectrum of the stable cyclized form. The effects of changing the desolvation temperature in the ionization source of the Q-TOF mass spectrometer were also investigated. Increasing the desolvation temperature had little effect on positive ion ESI mass spectra, but in negative ion spectra, a charge envelope at lower m/z appeared, consistent with an increase in the abundance of unfolded protein molecules.

Citation Information
Stephen J. Watt, Margaret Sheil, Jennifer L Beck, Pavel Prosselkov, et al.. "Effect of protein stabilization on charge state distribution in positive- and negative ion electrospray ionization mass spectra" (2007) p. 1605 - 1611
Available at: http://works.bepress.com/nick_dixon/88/