Journal of the American Society for Mass Spectrometry

, Volume 18, Issue 11, pp 1932–1944

Quantitative comparison of IMAC and TiO2 surfaces used in the study of regulated, dynamic protein phosphorylation

  • Xiquan Liang
  • Geir Fonnum
  • Mahbod Hajivandi
  • Torkel Stene
  • Nini H. Kjus
  • Erlend Ragnhildstveit
  • Joseph W. Amshey
  • Paul Predki
  • R. Marshall Pope
Articles

DOI: 10.1016/j.jasms.2007.08.001

Cite this article as:
Liang, X., Fonnum, G., Hajivandi, M. et al. J Am Soc Mass Spectrom (2007) 18: 1932. doi:10.1016/j.jasms.2007.08.001

Abstract

Protein phosphorylation regulates many aspects of cellular function, including cell proliferation, migration, and signal transduction. An efficient strategy to isolate phosphopeptides from a pool of unphosphorylated peptides is essential to global characterization using mass spectrometry. We describe an approach employing isotope tagging reagents for relative and absolute quantification (iTRAQ) labeling to compare quantitatively commercial and prototypal immobilized metal affinity chelate (IMAC) and metal oxide resins. Results indicate a prototype iron chelate resin coupled to magnetic beads outperforms either the Ga3+-coupled analog, Fe3+, or Ga3+-loaded, iminodiacetic acid (IDA)-coated magnetic particles, Ga3+-loaded Captivate beads, Fe3+-loaded Poros 20MC, or zirconium-coated ProteoExtract magnetic beads. For example, compared with Poros 20MC, the magnetic metal chelate (MMC) studied here improved phosphopeptide recovery by 20% and exhibited 60% less contamination from unphosphorylated peptides. With respect to efficiency and contamination, MMC performed as well as prototypal magnetic metal oxide-coated (TiO2) beads (MMO) or TiO2 chromatographic spheres, even if the latter were used with 2,5-dihydroxybenzoic acid (DHB) procedures. Thus far, the sensitivity of the new prototypes reaches 50 fmol, which is comparable to TiO2 spheres. In an exploration of natural proteomes, tryptic (phospho)peptides captured from stable isotopic labeling with amino acids in cell culture (SILAC)-labeled immunocomplexes following EGF-treatment of 5 × 107 HeLa cells were sufficient to quantify stimulated response of over 60 proteins and identify 20 specific phosphorylation sites.

Download to read the full article text

Supplementary material

13361_2011_181101932_MOESM1_ESM.ppt (1.3 mb)
Supplementary material, approximately 1343 KB.

Copyright information

© American Society for Mass Spectrometry 2007

Authors and Affiliations

  • Xiquan Liang
    • 1
  • Geir Fonnum
    • 1
  • Mahbod Hajivandi
    • 1
  • Torkel Stene
    • 1
  • Nini H. Kjus
    • 1
  • Erlend Ragnhildstveit
    • 1
  • Joseph W. Amshey
    • 1
  • Paul Predki
    • 1
  • R. Marshall Pope
    • 1
  1. 1.Protein Analysis, R and D DepartmentInvitrogen CorporationCarlsbadUSA