Redox regulation of helical structures in short peptides with an intramolecular ferrocenyl cross-linking agent

(Chemical Equation Presented) We redox-regulated α-helicity of short peptides intramolecularly cross-linked with a ferrocenyl linker between amino acid side chains. The helical content of the cross-linked peptide was estimated to be 56% in the neutral state of the ferrocene core at 25°C. The addition of an oxidant to the solution of the cross-linked peptide enhanced the helicity up to 75%. The increased helical content returned to the same level as that in the previous ferrocene state by further addition of a reductant.