FIGURE 1.

Electron micrograph of PFOs and APFs and circular dichroism spectrum of APFs. A, Aβ42 PFO preparation used as the starting material for APF preparation. B, Aβ42 APFs prepared by mixing with 5% hexanes appear as ring or pore-like structures of varying diameter from 8 to 25 nm. They are obtained in a relatively homogenous and pure population, although small amounts of 3–5-nm spherical oligomers are also observed in the population. Immediately after preparation, the APFs have a rough or beaded appearance that is 3–5 nm in diameter that suggests that APFs form by the coalescence of prefibrillar spherical oligomers as previously suggested. Inset, after incubation for 1 week at 25 °C, the APFs lose the rough, beaded appearance and become smooth. Figures that appear to result from the concatenation of multiple APFs are also observed. C, Aβ40 APFs after 1 week of incubation. D, α-synuclein APFs after 1 week of incubation. E, circular dichroism spectrum of APFs demonstrating the β-sheet character of APFs.