Increasing charge while preserving noncovalent protein complexes for ESI-MS

  • Shirley H. Lomeli
  • Sheng Yin
  • Rachel R. Ogorzalek Loo
  • Joseph A. Loo
Short Communication

DOI: 10.1016/j.jasms.2008.11.013

Cite this article as:
Lomeli, S.H., Yin, S., Ogorzalek Loo, R.R. et al. J Am Soc Mass Spectrom (2009) 20: 593. doi:10.1016/j.jasms.2008.11.013

Abstract

Increased multiple charging of native proteins and noncovalent protein complexes is observed in electrospray ionization (ESI) mass spectra obtained from nondenaturing protein solutions containing up to 1% (vol/vol) m-nitrobenzyl alcohol (m-NBA). The increases in charge ranged from 8% for the 690 kDa α7β7β7α7 20S proteasome complex to 48% additional charge for the zinc-bound 29 kDa carbonic anhydrase-II protein. No dissociation of the noncovalently bound ligands/subunits was observed upon the addition of m-NBA. It is not clear if the enhanced charging is related to altered surface tension as proposed in the “supercharging” model of Iavarone and Williams (Iavarone, A. T.; Williams, E. R. J. Am. Chem. Soc.2003, 125, 2319–2327). However, more highly charged noncovalent protein complexes have utility in relaxing slightly the mass-to-charge (m/z) requirements of the mass spectrometer for detection and will be effective for enhancing the efficiency for tandem mass spectrometry studies of protein complexes.

Supplementary material

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Copyright information

© American Society for Mass Spectrometry 2009

Authors and Affiliations

  • Shirley H. Lomeli
    • 1
  • Sheng Yin
    • 1
  • Rachel R. Ogorzalek Loo
    • 2
  • Joseph A. Loo
    • 1
    • 2
  1. 1.Department of Chemistry and BiochemistryUniversity of California-Los AngelesLos AngelesUSA
  2. 2.Department of Biological Chemistry, David Geffen School of MedicineUniversity of California-Los AngelesLos AngelesUSA
  3. 3.Molecular Biology InstituteUniversity of California-Los AngelesLos AngelesUSA