Exploiting terminal charged residue shift for wide bilayer nanotube assembly

Area of Science:

• Biomaterials Science
• Supramolecular Chemistry
• Nanotechnology

Background:

• Peptide self-assembly is governed by molecular structure and environmental factors, influencing non-covalent interactions.
• Terminal charge residues play a critical role in modulating these interactions and the resulting self-assembly morphologies.
• Understanding this relationship is key to controlling peptide self-assembly for targeted applications.

Purpose of the Study:

• To investigate the impact of terminal charge residue position on peptide self-assembly.
• To demonstrate the transformation of peptide self-assembly morphologies by shifting a lysine residue.
• To reveal the underlying mechanism driving morphology transitions.

Main Methods:

• Synthesized and characterized two ultrashort peptides with differing lysine residue positions (Ac-I3K-NH2 and Ac-KI3-NH2).
• Employed a combination of experimental techniques to analyze the morphologies and structures of self-assemblies.
• Systematically studied the effect of terminal residue placement on self-assembly outcomes.

Main Results:

• A shift of the C-terminal lysine to the N-terminus (Ac-KI3-NH2) resulted in the formation of giant nanotubes with a bilayer shell.
• Intermolecular C-terminal hydrogen bonding in Ac-KI3-NH2 promoted a bola-form geometry, essential for wide nanotube formation.
• The self-assembly process followed a 'growing width' model, applicable to other peptide analogues.

Conclusions:

• Terminal charge residue positioning is a powerful tool for controlling peptide self-assembly morphology.
• This strategy provides a straightforward method for synthesizing wide peptide nanotubes.
• The findings contribute to expanding the library of peptide nanostructures for template-based prediction and design.