Figure 6.

Influence of salt on the FTIR spectra of Aβ40-WT, Aβ40-Dutch, Aβ40-Iowa, and Aβ42-WT. FTIR spectra of the four peptides are shown with the addition of 10 mM NaCl. The striking feature with the addition of salt is the transient increase in the intensity in the spectra of the Aβ40-Dutch peptide during fibril formation at 1670–1680 cm^–1, which is interpreted as an increase in the level of random coil structure. An alternative explanation is that this band results from novel α-sheet structure described by Dagget and co-workers.⁶⁸ The temperature was maintained at 37 °C during incubation.