Combined Pulsed-Q Dissociation and Electron Transfer Dissociation for Identification and Quantification of iTRAQ-Labeled Phosphopeptides
journal contributionposted on 2009-05-15, 00:00 authored by Feng Yang, Si Wu, David L. Stenoien, Rui Zhao, Matthew E. Monroe, Marina A. Gritsenko, Samuel O. Purvine, Ashoka D. Polpitiya, Nikola Tolić, Qibin Zhang, Angela D. Norbeck, Daniel J. Orton, Ronald J. Moore, Keqi Tang, Gordon A. Anderson, Ljiljana Paša-Tolić, David G. Camp, Richard D. Smith
Here, we report a new approach that integrates pulsed Q dissociation (PQD) and electron transfer dissociation (ETD) techniques for confident and quantitative identification of iTRAQ-labeled phosphopeptides. The use of isobaric tags for relative and absolute quantification enables a high-throughput quantification of peptides via reporter ion signals in the low m/z range of tandem mass spectra. PQD, a form of ion trap collision activated dissociation, allows for detection of low mass-to-charge fragment ions, and electron transfer dissociation is especially useful for sequencing peptides that contain post-translational modifications. Analysis of the phosphoproteome of human fibroblast cells using a sensitive linear ion trap mass spectrometer demonstrated that this hybrid approach improves both identification and quantification of phosphopeptides. ETD improved phosphopeptide identification, while PQD provides improved quantification of iTRAQ-labeled phosphopeptides.