Conformational Switch of Arylopeptide: Helix-Helix Transition Based on Side Chain Solvation

Controlling the structural transition between well-defined architectures found in living system is essential in polymer chemistry as well as material science. Herein, the reversible conformational switch of a non-natural polypeptide with an aromatic ring (2,6-naphthalene spacer) on its peptide backbone, referred to as an arylopeptide, between two distinct well-defined helical structures (extended 3(1)-helix and contracted 4(1)-helix) using side chain solvation is demonstrated. The folding selectivity of the arylopeptide and found that the affinity between the solvent and side chains is an essential factor for determining the global structure is investigated. A thermoresponsive arylopeptide bearing oligoether groups (-(CH2CH2O)(9)CH3)) on the side chain is designed, which exhibited unique lower critical solution temperature behavior and converted from the 3(1) to the 4(1)-helix depending on the temperature. Furthermore, the solvent affinity of the entire polymer by combining substituents (-(CH2CH2O)(3)CH3 and -C12H25) with different properties on the side chains to achieve a spring-like expansion-contraction system that allows interconversion between 3(1)- and 4(1)-helices is adjusted.

Automated summary

The study demonstrates the reversible conformational switch of an arylopeptide between two distinct helical structures using side chain solvation, and investigates folding selectivity and solvent-side chain affinity in determining the global structure. A thermoresponsive arylopeptide with oligoether groups and an adjustment of solvent affinity by combining different side chain substituents were designed to achieve interconversion between helices.