Identification of phosphorylated human peptides by accurate mass measurement alone

Yuan Mao, Leonid Zamdborg, Neil L. Kelleher, Christopher L. Hendrickson, Alan G. Marshall*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


At sufficiently high mass accuracy, it is possible to distinguish phosphorylated from unmodified peptides by mass measurement alone. We examine the feasibility of that idea, tested against a library of all possible in silico tryptic digest peptides from the human proteome database. The overlaps between in silico tryptic digest phosphopeptides generated from known phosphorylated proteins (1-12 sites) and all possible unmodified human peptides are considered for assumed mass error ranges of ±10, ±50, ±100, ±1000, and ±10,000 ppb. We find that for mass error ±50 ppb, 95% of all phosphorylated human tryptic peptides can be distinguished from nonmodified peptides by accurate mass alone throughout the entire nominal mass range. We discuss the prospect of on-line LC MS/MS to identify phosphopeptide precursor ions in MS1 for selected dissociation in MS2 to identify the peptide and site(s) of phosphorylation.

Original languageEnglish (US)
Pages (from-to)357-361
Number of pages5
JournalInternational Journal of Mass Spectrometry
Issue number2-3
StatePublished - Dec 1 2011


  • Exact mass
  • FTMS
  • Fourier transform mass spectrometry
  • Human proteome
  • ICR
  • Ion cyclotron resonance

ASJC Scopus subject areas

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


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