Self-Assembly of Peptide Nanotubes in an Organic Solvent

The self-assembly of a modified fragment of the amyloid β peptide, based on sequence Aβ(16−20), KLVFF, extended to give AAKLVFF is studied in methanol. Self-assembly into peptide nanotubes is observed, as confirmed by electron microscopy and small-angle X-ray scattering. The secondary structure of the peptide is probed by FTIR and circular dichroism, and UV/visible spectroscopy provides evidence for the important role of aromatic interactions between phenylalanine residues in driving β-sheet self-assembly. The β-sheets wrap helically to form the nanotubes, the nanotube wall comprising four wrapped β-sheets. At higher concentration, the peptide nanotubes form a nematic phase that exhibits spontaneous flow alignment as observed by small-angle neutron scattering.