Probing asymmetric charge partitioning of protein oligomers during tandem mass spectrometry

Philip D. Compton, Luca Fornelli, Neil L. Kelleher*, Owen S. Skinner

*Corresponding author for this work

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Dissociation of gaseous protein complexes produced by native electrospray often induces an asymmetric partitioning of charge between ejected subunits. We present a simple asymmetric charge partitioning factor (ACPF) to quantify the magnitude of asymmetry in this effect. When applied to monomer ejection from the cytochrome c dimer and β-amylase tetramer, we found that the ∼60-70% of precursor charge ending up in the ejected monomers corresponds to ACPFs of 1.38 and 2.51, respectively. Further, we used site-specific fragmentation from electron transfer dissociation (ETD) to identify differences in fragmentation and characterize domains of secondary-structure present in the dimer, ejected monomers, and monomers obtained directly from electrospray ionization (ESI). We found evidence of structural changes between the dimer and ejected monomer, but also that the ejected monomer had a nearly identical set of fragment ions produced by ETD as the ESI monomer with the same charge state. Surprisingly, ACPF values for ETD fragment ions generated directly from the dimer revealed that the fragments undergo asymmetric charge partitioning at over twice the magnitude of that observed for ejection of the monomer.

Original languageEnglish (US)
Article number15491
Pages (from-to)132-136
Number of pages5
JournalInternational Journal of Mass Spectrometry
Volume390
DOIs
StatePublished - Aug 29 2015

Keywords

  • Asymmetric charge partitioning
  • Electron transfer dissociation
  • Protein complexes
  • Proteomics

ASJC Scopus subject areas

  • Instrumentation
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry

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