Figure 3

MS analysis of H ₂ O ₂ -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.