Fig. 1: Hydroxylation of αSyn at the Tyr136 residue by TH treatment.
From: DOPAnization of tyrosine in α-synuclein by tyrosine hydroxylase leads to the formation of oligomers
a Digestion process of αSyn by trypsin (upper) and Asp-N (lower). Trypsin digestion yielded two tyrosine (red)-containing fragments (blue), whose sequences were boxed. A fragment of residues 103–140 of αSyn (103–140 aa) was further digested by Asp-N, yielding five fragments, as shown by the boxed sequences. Here, Asp-N atypically cleaves the N-terminus of Glu126 but fails at N-terminus of Asp121. b MALDI-TOF mass spectrum of the fragment corresponding to 135–140 aa. The peak at m/z 723.19 corresponds to 135–140 aa (control, left). After TH treatment (right), an additional peak at m/z 739.18 showed an increment of 16 mass units compared to that of the 135–140 aa fragment. The peak at m/z 745.2 corresponds to sodium adduct form of the 135–140 aa. c MALDI-TOF MS/MS spectrum of the MS peak at m/z 723.2 (upper) or m/z 739.2 (lower) in the TH-treated sample derived from (b). Fragmentation sites are indicated in the boxed area. The peptide sequences of fragmentated ions are shown above each peak, identifying the site of dopanization as Tyr136.
