Tuning Self-Assembled Nanostructures Through Enzymatic Degradation of a Peptide Amphiphile

[Image: see text] The enzymatic cleavage of a peptide amphiphile (PA) is investigated. The self-assembly of the cleaved products is distinct from that of the PA substrate. The PA C(16)-KKFFVLK is cleaved by α-chymotrypsin at two sites leading to products C(16)-KKF with FVLK and C(16)-KKFF with VLK. The PA C(16)-KKFFVLK forms nanotubes and helical ribbons at room temperature. Both PAs C(16)-KKF and C(16)-KKFF corresponding to cleavage products instead self-assemble into 5–6 nm diameter spherical micelles, while peptides FVLK and VLK do not adopt well-defined aggregate structures. The secondary structures of the PAs and peptides are examined by FTIR and circular dichroism spectroscopy and X-ray diffraction. Only C(16)-KKFFVLK shows substantial β-sheet secondary structure, consistent with its self-assembly into extended aggregates, based on PA layers containing hydrogen-bonded peptide headgroups. This PA also exhibits a thermoreversible transition to twisted tapes on heating.