Constitutionally Isomeric Aromatic Tripeptides: Self-Assembly and Metal-Ion-Modulated Transformations

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Biophysics

Background:

• Aromatic amino acid-based peptides self-assemble into various nanostructures.
• Molecular structure dictates peptide self-assembly outcomes.
• Amyloid β peptides feature FF motifs, influencing self-assembly.

Purpose of the Study:

• To investigate the self-assembly behavior of rationally designed aromatic peptide constitutional isomers.
• To understand the molecular-level determinants of peptide self-assembly.
• To explore the influence of transition-metal ions on peptide nanostructure formation.

Main Methods:

• Rational design of two tripeptide constitutional isomers (tyrosine at N-terminus vs. C-terminus of FF peptide).
• Characterization of self-assembled nanostructures using microscopy and spectroscopy.
• Investigation of peptide self-assembly in the presence of transition-metal ions (Cu2+, Zn2+, Fe2+).

Main Results:

• The N-terminal tyrosine isomer formed 2D porous nanosheets ('Nanowebs').
• The C-terminal tyrosine isomer formed toroidal shapes with central spheres ('Nano-Saturn' assemblies).
• Transition-metal ions induced the formation of fibrous circular discs, nanomats, and nanoplates from both isomers.

Conclusions:

• Constitutional isomerism significantly impacts peptide self-assembly into distinct nanostructures.
• Transition-metal ions act as triggers, directing peptide self-assembly towards novel morphologies.
• This study provides insights into the rational design of peptide-based nanomaterials.