Figure 2: Cross-seeding capacities of the two α-syn polymorphs.

Elongation of preformed α-syn fibrils (red data points) and ribbons (blue data points), 10 μM in (a) buffer A (50 mM Tris-HCl, pH 7.5, 150 mM KCl), (b) buffer B (5 mM Tris-HCl, pH 7.5), at 37 °C, in the presence of soluble α-syn (100 μM), monitored by measurement of scattered light at 440 nm. The control assembly reactions of soluble α-syn in the absence of preformed seeds (black data points) are also shown. When the seeded assembly reactions were centrifuged immediately after addition of the seeds (40,000 g for 30 min at 20 °C) and the supernatant and pellet fractions analysed by SDS–PAGE, the pellets contained the added seeds (fibrils or ribbons, 10% of the protein), whereas the supernatants contained the soluble α-syn (90% of the protein content of the solution). The amount of α-syn in the pellet and supernatant fractions at the indicated time (2, 24 and 150 h) in the absence (black letters) or the presence of α-syn fibrils (red letters) and ribbons (blue letters) seeds revealed by Coomassie blue stained SDS–PAGE are also shown. The inset in (a) corresponds to a blow-up on the initial stages of the assembly reactions. Electron micrographs and SDS–PAGE proteinase K degradation patterns of α-syn assemblies generated upon addition of preformed α-syn fibrils and ribbons are shown. The time (in min) and molecular weight markers (in kDa) are shown on the top and left of each Coomassie blue stained SDS–PAGE. The scale bars in the electron micrographs correspond to 200 nm.