Structure of single-wall peptide nanotubes: in situ flow aligning X-ray diffraction.

The structure of single wall peptide nanotubes is presented for the model surfactant-like peptide A(6)K. Capillary flow alignment of a sample in the nematic phase at high concentration in water leads to oriented X-ray diffraction patterns. Analysis of these, accompanied by molecular dynamics simulations, suggests the favourable self-assembly of antiparallel peptide dimers into beta-sheet ribbons that wrap helically to form the nanotube wall.