Investigation of Gas-phase Phosphate Transfer of Phosphopeptides in Tandem Mass Spectrometry Using Collision-induced Dissociation and Electron Transfer Dissociation

摘要

One of the challenges in phosphoproteomics is to determine the phosphorylation site(s) along with the identification of the peptide sequence, especially for those containing multiple potential phosphorylation sites. In addition to the neutral loss of H_(3)PO_(4) (-98 Da) and HPO_(3) (-80 Da), the recent studies [1, 2] demonstrated that collision-induced dissociation (CID) could induce phosphate transfer within a phosphopeptide being analyzed. Such HPO_(3) neutral loss and phosphate transfer could result in ambiguity or mis-assignment in phosphosite determination. To address this issue, we conducted a detailed study of fragmentation of phosphopeptides that contain multiple serine and/or threonine residues using CID and electron transfer dissociation (ETD) tandem mass spectrometry (MS/MS). It is expected that the results could provide new solutions to the determination of exact phosphorylation site(s).