Modulation of Aβ(1-40) peptide fibrillar architectures by Aβ-based peptide amphiphiles.

Modulation of the fibrillogenesis of amyloid peptide Aβ(1-40) with two Aβ-based peptide amphiphiles has been studied. Both peptide amphiphiles contain two alkyl chains but in different positions. The two alkyl chains of 2C12-Aβ(11-17) are attached to the same terminus of Aβ(11-17), while those of C12-Aβ(11-17)-C12 are separately attached to opposite termini of Aβ(11-17). Thioflavin T fluorescence spectroscopy shows that all the peptide amphiphiles promote the formation of the cross-β-sheet structure of Aβ(1-40) and the aggregation of Aβ(1-40), while 2C12-Aβ(11-17) does this more efficiently. The atom force microscopy images indicate that the modulations of these two peptide amphiphiles on the Aβ(1-40) aggregation experience two distinct pathways. 2C12-Aβ(11-17) leads to amorphous aggregates, whereas C12-Aβ(11-17)-C12 generates short rodlike fibrils. However, Fourier transform infrared spectroscopy suggests that the amorphous aggregates and rodlike fibrils display similar secondary structures. This work suggests that the aggregation ability and the aggregate structures of the peptide amphiphiles significantly affect their interactions with Aβ(1-40) and lead to different morphologies of the Aβ(1-40) aggregates.