Fig. 6: Cross-seeding kinetics, TEM, and Raman spectroscopy of single-Ala mutants seeded with 66‒140 fibrils.

a Aggregation kinetics monitored by ThT (10 µM) of soluble 66–140 (black), K80A (blue), E83A (magenta), K96A (purple), K97A (green), D98A (gold) and K102A (teal) (30 µM) seeded with 66–140 fibrils (0.3 µM) in pH 7.4 buffer (20 mM NaPi, 140 mM NaCl) at 37 °C with continuous linear shaking in the absence of 2 mm glass beads. Solid lines and shaded regions represent mean and SD, respectively (n ≥ 12). Precipitated (ppt) material calculated (%) after ultracentrifugation post-aggregation is shown for each mutant. b Representative TEM images taken post-seeding. Scale bar is 200 nm. Full images are shown in Supplementary Fig. 21. c Comparison of Raman fingerprint region of the cross-seeded (as colored in Fig. 6a) and unseeded Ala-mutant fibrils (black). Solid lines and shaded regions represent the mean and SD, respectively (n ≥ 15). Dashed lines indicate the frequency location of a distinguishing peak (1012.5 cm⁻¹) in 66–140. Spectra of the unseeded samples are the same as shown in Fig. 5a. Full spectra are shown in Supplementary Fig. 22. The bottom panel shows difference spectra generated by subtracting the average unseeded from the average seeded spectrum. The error has been propagated from the SD of the averaged spectra. Subscript f denotes fibrils. Source data are provided as a Source Data file.