Preparation of fibril-enriched Aβ

Aβ₁₋₄₂ peptides were dissolved in sterilized and distilled water to make a stock solution at a concentration of 0.1 mM and incubated at 37°C for 7 d to allow peptide aggregation and fibril formation (Lorenzo and Yankner, 1994; Reed-Geaghan et al., 2009). Amyloid fibril-enriched preparation was obtained by Aβ peptide incubated in water for at least 7 days. Fibrillar form of the peptide was confirmed by its ability to change thioflavine T fluorescence spectra, as described elsewhere (Hudson et al., 2009). Reverse peptides Aβ₄₂₋₁ were prepared with the same method serving as the negative control.