Coassembly of enantiomeric amphipathic peptides into amyloid-inspired rippled β-sheet fibrils.

Amphipathic peptides composed of alternating hydrophobic and hydrophilic amino acids self-assemble into amyloid-inspired, β-sheet nanoribbon fibrils. Herein, we report a new fibril type that is formed from equimolar mixtures of enantiomeric amphipathic peptides (L- and D-(FKFE)(2)). Spectroscopic analysis indicates that these peptides do not self-sort and assemble into enantiomeric fibrils composed of all-l and all-d peptides, but rather coassemble into fibrils that contain alternating L- and D-peptides in a "rippled β-sheet" orientation. Isothermal titration calorimetry indicates an enthalpic advantage for rippled β-sheet coassembly compared to self-sorted β-sheet assembly of enantiomeric peptides.