title: Ion mobility separation of isomeric phosphopeptides from a protein with variant modification of adjacent residues.
abstract: Ion mobility spectrometry (IMS), and particularly differential or field asymmetric waveform IMS (FAIMS), was recently shown capable of separating peptides with variant localization of post-translational modifications. However, that work was limited to a model peptide with Ser phosphorylation on fairly distant alternative sites. Here, we demonstrate that FAIMS (coupled to electrospray/mass spectrometry (ESI/MS)) can broadly baseline-resolve variant phosphopeptides from a biologically modified human protein, including those involving phosphorylation of different residues and adjacent sites that challenge existing tandem mass spectrometry (MS/MS) methods most. Singly and doubly phosphorylated variants can be resolved equally well and identified without dissociation, based on accurate separation properties. The spectra change little over a range of infusion solvent pH; hence, the present approach should be viable in conjunction with chromatographic separations using mobile phase gradients.
authors.affiliation: Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA. alexandre.shvartsburg@pnl.gov
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: Shvartsburg
authors.forename: David
authors.initials: D
authors.lastname: Singer
authors.forename: Richard D
authors.initials: RD
authors.lastname: Smith
authors.forename: Ralf
authors.initials: R
authors.lastname: Hoffmann
mesh_terms: D007477:Ions; D007536:Isomerism; D010748:Phosphopeptides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D007477:Ions; D010748:Phosphopeptides