Presentation day

Tuesday  4:00 PM

 

TITLE

Surfactant-like peptides leading to self-assembled structures

 

Abstract

Surfactant-like peptides (APs) have attracted attention over the past decade because they
exhibit not only high surface activities but also unique self-assemble properties into a broad range of
nanostructures. These unique properties are dictated by their amphiphilic nature resulting from the
localization of hydrophilic (non-polar) and hydrophobic (polar) amino acids that can participate in secondary
structures such as α-helices and β-sheets. The interplay of intermolecular hydrogen bonding along with
hydrophobic and electrostatic interactions leads to self-assembled nanostructures.
In this study, we focused on two types of APs that afford α-helices or β-sheets in their structures. Firstly, we
synthesized an amphiphilic helical peptide that mimics helix 10 (residues 220-241) of human apo A-І. The
resulting helical peptide indicated a critical association concentration (CAC) of 2.7 × 10-5 M and a γCAC of
51.2 mN/m in water, and it self-assembled into disc-like nanostructure with a diameter of 9.5 nm ± 2.7 nm
by solubilizing phospholipid bilayers.
We also evaluated on the surface and self-assembling properties of surfactin having a unique cyclic peptide
moiety that affords a β-sheet structure in water, produced by Bacillus subtilis. It gave CAC of 2.7 × 10-5 M
and a γCAC of 27.2 mN/m, and self-assembled into giant spherical micelles in water. These results
demonstrated that both the secondary structures of APs play an important role in their unique surface and
self-assembling properties.