Figure 3
From: PhosCalc: A tool for evaluating the sites of peptide phosphorylation from Mass Spectrometer data
Example of results of PhosCalc for the peptide FQSEEQQQTEDELQDK with annotated MS3 spectrum from Sequest. A) PhosCalc output. B) Spectrum from a correct assignment. C) The same spectrum as 'B' with an incorrect assignment. Peaks marked in blue and marked with empty circles are matched to b or y ions by Sequest and * marks those peaks that do not match with the incorrect position of phosphorylation. For clarity only singly charged b and y ions without further loss of OH or NH3 groups are annotated, with the exception of the intense y14 2+ ion.