Dual Control of Peptide Conformation with Light and Metal Coordination.

The design of a stimuli-responsive peptide whose conformation is controlled by wavelength-specific light and metal coordination is described. The peptide adopts a defined tertiary structure and its conformation can be modulated between an α-helical coiled coil and β-sheet. The peptide is designed with a hydrophobic interface to induce coiled coil formation and is based on a recently described strategy to obtain switchable helix dimers. Herein, we endowed the helix dimer with 8-hydroxyquinoline (HQ) groups to achieve metal coordination and shift to a β-sheet structure. It was found that the conformational shift only occurs upon introduction of Zn2+ ; other metal ions (Cu2+ , Fe3+ , Co2+ , Mg2 , and Ni2+ ) do not offer switching likely due to non-specific metal-peptide coordination. A control peptide lacking the metal-coordinating residues does not show conformational switching with Zn2+ supporting the role of this metal in stabilizing the β-sheet conformation in a defined manner.