Fig. 6. Characterization of Myo-D127ppS, and off-target phosphorylation sites. (a) Sequence of myoglobin with MS/MS coverage highlighted in grey. Red residues: off-target phosphorylation sites; green residue: pyrophosphorylation site (methionine residues highlighted in yellow were found to be partially oxidized). (b) Ion abundances of peptides bearing ppS127 product (green), pS127 starting material (blue), and off-target phosphorylation sites (red). See Table S2† for peptide sequences and ion counts, Fig. S22† for a detailed graphical representation of the off-target ion abundances, and Fig. S23† for single ion chromatograms of pS and ppS-bearing peptides. (c) EThcD MS/MS of the pyrophosphorylated peptide fragment ion.
