Nanotube formation by hydrophobic dipeptides.

A wide range of applications has been suggested for peptide-based nanotubes, which first attracted considerable interest as model systems for membrane channels and pores. The intriguing and unprecedented observation of nanotube formation by supramolecular self-assembly of the four dipeptides L-Leu-L-Leu, L-Leu-L-Phe, L-Phe-L-Leu and L-Phe-L-Phe is described here. These simple compounds crystallize with hydrogen-bonded head-to-tail chains in the shape of helices with four to six peptide molecules per turn. The resulting structures have chiral hydrophilic channels with a van der Waals' diameter up to 10 A.