PTM Site Localization And Isomer Differentiation Of Phosphorylated Peptides

By Joanna Bons, Jason Cason, Birgit Schilling, and Christie Hunter

Protein phosphorylation is an important post-translational modification (PTM) as it is involved in a large variety of dynamic cellular processes. However, PTM site localization and quantification of phosphopeptides by collision induced dissociation (CID) MS/MS can be challenging, and phospho-peptides can exhibit a partial neutral loss of the phospho group (-98 Th).

In this study, the use and benefits of EAD fragmentation for phosphopeptide analysis, site-localization and differentiation, and MS/MS-based phosphopeptide quantification were evaluated.