Proteinase K (PK) digestion of α-syn PFF

PK digestion was performed as previously described (30). Ten micrograms of α-syn PFF or PAR-α-syn PFF were mixed with 0.5 to 2.5 μg/ml of PK in PBS and incubated at 37°C for 30 min. The reaction was stopped by adding 1 mM PMSF, boiled with SDS-sample buffer for 5 min. The bands of the PK digestion products were detected by immunoblotting using epitope-specific α-syn antibodies (Table S4).