Autofluorescence of Amyloids Determined by Enantiomeric Composition of Peptides

Amyloid fibrils are peptide or protein aggregates possessing a cross-beta-sheet structure. They possess intrinsic fluorescence property, which is still not fully understood. Herein, we compare structural and optical properties of fibrils formed from L- and D-enantiomers of the (105-115) fragment of transthyretin (TTR) and from their racemic mixture. Our results show that autofluorescence of fibrils obtained from enantiomers differs from that of fibrils from the racemic mixture. In order to elucidate the origin of observed differences, we analyzed the structure and morphology of fibrils and showed how variations in beta-sheet organization influence optical properties of fibrils. We clarified the contribution of aromatic rings and the amyloid backbone to the final blue-green emission of fibrils. This work demonstrates how enantiomeric composition of amino acids allows us to modulate the self-assembly and final morphology of well-defined fibrillar bionanostructures with optical properties controlled by supramolecular organization.

Automated summary

This study compared the structural and optical properties of amyloid fibrils formed from L- and D-enantiomers, as well as their racemic mixture, revealing differences in autofluorescence. The research clarified how variations in beta-sheet organization influence the optical properties of fibrils, particularly the contribution of aromatic rings and the amyloid backbone to the blue-green emission. It demonstrated how the enantiomeric composition of amino acids can modulate the self-assembly and morphology of fibrillar bionanostructures with controlled optical properties.