Self-Assembly of Tyrocidines in Nanotubular Structures

Abstract

AbstractHollow tubular structures of tyrocidines, a cyclic decapeptide with two amino acids residues in the D-configuration and eight in the L-configuration, were formed in acid aqueous solutions in the presence of ethanol (20°C). Discrete nanotubes can be produced under controlled conditions, e.g. the amount of water added, or in the presence of protons from ethanol-water solutions (45/55 %v/v). These cyclic oligopeptides crystallize into tubular structures hundreds of nanometer long with an internal diameter of 9.0 Å and outer diameter of 35 Å. Support for the proposed tubular structure is provided by electronmicroscopy, SAXS and Fourier-transform infrared spectroscopy. These structures are open-ended, having a uniform shape and constant internal diameter.