Fixed Charge Derivatization for Enhanced Quantitative Collision Induced Dissociation (CID) and 'Targeted' Data-Dependant Electron Transfer Dissociation (ETD) Characterization of Phosphopeptides

摘要

Protein phosphorylation is involved in the regulation of a wide variety of in-vivo biological functions. These functions are highly dependent on the location at which proteins are phosphorylated. Commonly, phosphorylation sites are identified by tandem mass spectrometry (MS/MS), typically employing collision induced dissociation (CID) or electron transfer dissociation (ETD) as the activation technique. Unfortunately, unambiguous phosphate group localization by using CID-MS/MS can be hampered due to the facile loss of the PTM or intrapeptide phosphate group rearrangements, particularly for low charge state precursor ions [Anal. Chem. 2008, 80, 9735-9747]. ETD has an improved ability to localize phosphate groups, but can be limited in that it optimally requires the precursor ions to be highly multiply-charged. Here, we describe an improved CID neutral loss and data dependant triggered ETDMS/MS or MS~(3) method for phosphopeptide/phosphoprotein characterization.