De novo α-synuclein fibrils are prepared by incubating 500 µL of 100 µM α-synuclein monomer in 20 mM sodium phosphate buffer with 150 mM NaCl in a 1.5 mL Eppendorf tube that is incubated at 37 • C for 14 days. The solution is shaken at 1200 rpm with a 1 mm diameter glass bead using a Eppendorf Ther-moMixer. All subsequent fibril solutions are prepared from 5% equivalent monomer mass seeding from the original fibril sample. 500 µL of 100 µM α-synuclein monomer, in a 1.5 mL Eppendorf tube is incubated at 37 • C in 20 mM sodium phosphate buffer with 150 mM NaCl for 3 days. The solution is shaken at 1200 rpm with a 1 mm diameter glass bead. In order to prepare the seeds, α-synuclein fibrils were sonicated for 5 minutes (25 minute cycle, 2s sonication, 8s break) on ice using a MS72 probe sonicator at 10% amplitude.