Fig. 3

Aβ38 can seed fibril formation in vitro. a ThT amyloid binding dye-based aggregation kinetics of 3 µM solutions of recombinant Aβ38, Aβ40, and Aβ42 peptides prepared in aggregation buffer with 20 µM ThT. Monomeric peptide solutions were prepared using GuHCl solubilization prior to setting up the experiments. b Representative negative staining electron microscopy images of recombinant Aβ38, Aβ40, and Aβ42 peptides incubated for 72 h at room temperature. c Dot blot analysis using LOC antibody reveals relative levels of inherent fibrils formed in vitro from recombinant Aβ38, Aβ40 and Aβ42 peptides following GuHCl solubilization. Scramble Aβ42 peptides were used as negative control. Ponceau S-stained membranes were used for visualization of loading protein amount. d, e Dot blot analysis using LOC antibody for peptides obtained from 24 h incubation of 3 µM monomeric Aβ42 alone or with other monomeric peptides incubated at 100 nM concentration. Ponceau S-stained membranes were used for visualization of loading protein amount. f ThT-based amyloid kinetics of two-peptide system consisting of 3 µM Aβ42 in absence or presence of other peptides (Aβ38, Aβ40 and scramble Aβ42) at 100 nM concentration. The relative amyloid concentrations were calculated using secondary nucleation model in AmyloFit online tool (https://amylofit.com/amylofitmain). ThT fluorescence intensities were measured every four minutes. N = 3 replicates (a, c), 5 (d-f). Scale bar = 50 nm (b)