Self-assembly of PAs composed of palmitic acid and several repeated heptad peptide sequences, C15H31CO-(IEEYTKK)n-NH2 (n = 1–4, represented by PA1–PA4), was investigated systematically. The secondary structures of the PAs were characterized by CD. PA3 and PA4 (n = 3 and 4, respectively) showed an α-helical structure, whereas PA1 and PA2 (n = 1 and 2, respectively) did not display an α-helical conformations under the tested conditions. The morphology of the self-assembled peptides in aqueous medium was studied by transmission electron microscopy. As the number of heptad repeats in the PAs increased, the nanostructure of the self-assembled peptides changed from nanofibers to nanovesicles. Changes of the secondary structures and the self-assembly morphologies of PA3 and PA4 in aqueous medium with various cations were also studied. The critical micelle concentrations were determined using a pyrene fluorescence probe. In conclusion, this method may be used to design new peptide nanomaterials. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.
We designed a series of four peptide amphiphiles (PAs) with varied heptad repeated peptide headgroup lengths. As the number of heptad repeats in the PAs increased, the secondary structures of the PAs tended to display α-helical conformations, and the nanostructure of the self-assembled peptides changed from nanofibers to nanovesicles. This research provides a useful way of modulating the self-assembly of α-helical PAs.