MS analysis of H
-induced parkin sulfonation. (A) - (F) DeCyder™ MS analysis of high-resolution nanoLC/ESI Q-TOF MS spectra for recombinant GST-parkin. Full length GST-parkin was exposed to H2O2 (B, D, F and H) and compared to vehicle-treated control (A, C, E and G). MS spectra displayed in DeCyder™ 2D gel format with insets showing higher resolution of MS datasets (A and B), and converted into "3D" format (C and D) representing the alkylated peptide 246SPVLVFQCNSR256. MS spectral analysis revealed that the sulfonated peptide [246SPVLVFQC(SO3H)NSR256] (F) was not found in the vehicle-treated control (E). Marked blue frames indicate the identified peptides by tandem MS. (G) and (H) Peptide 246SPVLVFQCNSR256 identified by high-sensitivity MS/MS ion trap as a double-charged ion with a carbamidomethyl (CAM)-modified cysteine at m/z 654.7 (G) or sulfonated (SO3H) cysteine at m/z 649.4 (H). Both spectra show characteristic "y" and "b" series ions. Red asterisks (*) indicates ions that contain the modified cysteine residue.