Figure 1.

Characterization of Aβ peptides. A and B: Solutions containing Aβ 42-1 and 1-42 were prepared as described in Materials and Methods and used to coat multispot slides. A: Spots coated with Aβ 42-1 and incubated with Thioflavin S for 1 minute remained unstained implying no fibril formation. B: Spots coated with Aβ 1-42 and incubated with Thioflavin S (Sigma) for 1 minute stained intensely. C: A transmission electron micrograph of negatively stained Aβ 1-42 fibrils (original magnification, ×65,000). D: Nonreducing SDS-PAGE of fAβ 1-42 and 42-1 peptides stained with Coomassie blue (Sigma). The lane containing fAβ 1-42 peptides shows two bands, one at ≅4.2 kd and one at ≅21 kd, whereas the lane containing 42-1 contains a single band at ≅4.2 kd.