CD spectra and TEM images of Aβ40 species.
Left panel shows
far-UV CD spectra of Aβ40 (1.5 mg/mL) dissolved in a 20 mM phosphate
buffer of pH 7.2, at room temperature (25 °C). In the panel,
the black line is the spectrum of the peptide monomer, recorded just
after preparing the solution, the red line is for the oligomer, and
the green line is for the fiber state of the peptide. Oligomer solution
was prepared in a 20 mM phosphate buffer of pH 7.2, and the incubation
time was 3 h. Aβ40 fiber was prepared in a 20 mM phosphate buffer
of pH 7.2 at T = 25 °C, and the incubation time
was 2 days (green line). The path length of the measuring cell was
0.1 cm, and each spectrum was an average of three scans. Right panel
shows TEM images of Aβ40 oligomer (A) and Aβ40 fiber (B).
The sample preparation condition was the same as above. Details of
the recording conditions are given in the Methods section. Size of
the scale bar is 100 nm.