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, beta-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 Land D-peptides in a rippled beta-sheet orientation. Isothermal titration calorimetry indicates an enthalpic advantage for rippled beta-sheet coassembly compared to self-sorted beta-sheet assembly of enantiomeric peptides.