Enantiomeric peptides self-assembling into fibrils with the same handedness

Area of Science:

• Supramolecular chemistry
• Peptide self-assembly
• Chirality

Background:

• Enantiomeric peptides are expected to form nanostructures with opposite supramolecular chirality.
• The relationship between molecular chirality and resulting supramolecular chirality is a key area of research.

Purpose of the Study:

• To investigate the supramolecular chirality of self-assembled polyphenylalanine peptides with different enantiomeric configurations.
• To explore potential discrepancies between molecular chirality and observed supramolecular chirality in peptide assemblies.

Main Methods:

• Synthesis of L- and D-polyphenylalanine peptides (e.g., F10, F9f, F5f5).
• Circular Dichroism (CD) spectroscopy to analyze chirality.
• Microscopy techniques to observe self-assembled nanostructures.

Main Results:

• L-polyphenylalanine F10 and its enantiomer f10 exhibited mirror-image CD spectra.
• Both enantiomeric peptides exclusively self-assembled into left-handed helical fibers.
• This exclusive left-handedness was consistent across other tested enantiomeric peptide pairs (F9f/f9F, F5f5/f5F5).

Conclusions:

• The study reveals an unexpected outcome where enantiomeric peptides yield supramolecular assemblies with the same handedness.
• Findings challenge the conventional understanding of chirality transfer from molecular building blocks to self-assembled peptide nanostructures.
• This work offers novel insights into the complex relationship governing peptide molecular chirality and supramolecular chirality.