In Silico Design of Short Peptides as Sensing Elements for Phenolic Compounds

We exploit a recently developed computational approach [I. Gladich et al, J. Chem. Phys. B, DOI: 10.1021/acs.jpcb.5b06227 (2015)] to design cyclic peptides capable to recognize chlorogenic acid and related phenolic compound. A peptide designed by this procedure was synthesized and characterized by circular dichroism and fluores-cence spectroscopy, cyclic voltammetry and differential pulse voltammetry. We found that the peptide is selective for chlorogenic acid against other ortho-diphenols such as caffeic acid, and mono-phenols as ferulic and coumaric acid. Indeed, when chlorogenic or caffeic acid are bound to the cyclic peptide, the ortho-diphenol moiety capable to undergo oxidation is not available to electrode surface due to diffusion limitation and steric hindrance. This phenomenon did not occur for cumaric and ferulic acid possibly because of limited complex formation with the cyclic peptide. In an electrochemical sensing system the peptide can therefore discriminate ortho-diphenols in a mixture of phenols.