Gas Phase Ion Chemistry to Determine Isoaspartate in a Peptide Backbone

  • S. T. Ayrton
  • X. Chen
  • R. M. Bain
  • C. J. Pulliam
  • M. Achmatowicz
  • T. G. Flick
  • D. Ren
  • R. G. Cooks
Research Article


Proof of concept evidence is presented for a new method for the determination of isoaspartate, an important post-translational modification. Chemical derivatization is performed using common reagents for the modification of carboxylic acids and shown to yield suitable diagnostic information with regard to isomerization at the aspartate residue. The diagnostic gas phase chemistry is probed by collision-induced dissociation mass spectrometry, on the timescale of the MS experiment and semi-quantitative calibration of the percentage of isoaspartate in a peptide sample is demonstrated.

Graphical Abstract


Mass spectrometry Isobaric peptide Post-translational modification Nanoelectrospray ionization 



The authors acknowledge financial support of this work by Amgen Inc. and appreciate valuable discussions with Dalton Snyder and Izydor Apostol.

Supplementary material

13361_2018_1923_MOESM1_ESM.docx (817 kb)
ESM 1 (DOCX 816 kb)


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Copyright information

© American Society for Mass Spectrometry 2018

Authors and Affiliations

  • S. T. Ayrton
    • 1
  • X. Chen
    • 1
  • R. M. Bain
    • 1
  • C. J. Pulliam
    • 1
  • M. Achmatowicz
    • 2
  • T. G. Flick
    • 2
  • D. Ren
    • 2
  • R. G. Cooks
    • 1
  1. 1.Department of ChemistryPurdue UniversityWest LafayetteUSA
  2. 2.Department of Analytical Research & DevelopmentAmgen Inc.Thousand OaksUSA

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