Peptide nanotubes self-assembled from leucine-rich alpha helical surfactant-like peptides

Abstract

The designed arginine-rich surfactant-like peptide R3L12 (arginine3-leucine12) is shown to form a remarkable diversity of self-assembled nanostructures in aqueous solution, depending on pH, including nanotubes, mesh-like tubular networks in three-dimensions...

Alpha helical surfactant-like peptides self-assemble into pH-dependent nanostructures

“…2c. These branched nanotubes are very similar to those previously reported by us for 0.04 wt% R 3 L 12 at pH 1, 51 which we proposed are built from a-helical antiparallel peptide dimers arranged perpendicular to the nanotube wall. The branching is believed to result from the increased energetic penalty of charged residues at nanotube ends at low pH.…”

“…In our recent Communication, we showed that it forms nanotubes (at pH 2-4) or nanotubular networks (at pH 1) in acidic aqueous solutions. 51 Here we show that nanotube network structures are formed at pH 7 and pH 9, and we present new data showing the a-helical conformation of the peptide in the nanotubes, for the first time from synchrotron SAXS with an extended q range covering the spacing associated with a-helical structures, as well as CD and FTIR spectroscopy. This provides a unique combination of structural and spectroscopic probes of the a-helical structure.…”

“…Concentrations studied were 0.04 and 0.07 wt% peptide, consistent with our previous work on acidic solutions of R 3 L 12 . 51 The self-assembled nanostructure turns out to be highly pH dependent, and a significant difference is observed between the morphology at pH 9 and pH 12. We additionally examined the behaviour at pH 13 because at pH 12.5 the calculated charge net charge of the peptide changes from +3 to 0 due to deprotonation of the arginine residues as its pK a is crossed.…”

“…[45][46][47][48][49][50] We have recently reported a novel peptide nanotube architecture, based on a-helical antiparallel peptide dimers of the designed surfactant-like peptide (SLP) R 3 L 12 . 51 These form nanotubes in acidic aqueous solution, in which the peptide dimers lie perpendicular to the tube walls in a so-called ''cross-a'' nanotube architecture. 51 Tubular network structures were also observed in very acidic solution, at pH 1.…”

“…51 These form nanotubes in acidic aqueous solution, in which the peptide dimers lie perpendicular to the tube walls in a so-called ''cross-a'' nanotube architecture. 51 Tubular network structures were also observed in very acidic solution, at pH 1. These nanotubes present arginine on the inner and outer walls of the nanotubes, which suggests potential uses in antimicrobial or biocatalytic materials.…”