A pH-Induced Reversible Conformational Switch Able to Control the Photocurrent Efficiency in a Peptide Supramolecular System.

Affiliation

Kubitzky S(1), Venanzi M(2), Biondi B(3), Lettieri R(2), De Zotti M(3), Gatto E(2).
Author information:
(1)Faculty of Engineering and Natural Sciences, Technische Hochschule Wildau, Wildau, 15745, Germany.
(2)Department of Chemical Science and Technologies, University of Rome Tor Vergata, 00133, Rome, Italy.
(3)Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131, Padova, Italy.

Abstract

External stimuli are potent tools that Nature uses to control protein function and activity. For instance, during viral entry and exit, pH variations are known to trigger large protein conformational changes. In Nature, also the electron transfer (ET) properties of ET proteins are influenced by pH-induced conformational changes. In this work, a pH-controlled, reversible 310 -helix to α-helix conversion (from acidic to highly basic pH values and vice versa) of a peptide supramolecular system built on a gold surface is described. The effect of pH on the ability of the peptide SAM to generate a photocurrent was investigated, with particular focus on the effect of the pH-induced conformational change on photocurrent efficiency. The films were characterized by electrochemical and spectroscopic techniques, and were found to be very stable over time, also in contact with a solution. They were also able to generate current under illumination, with an efficiency that is the highest recorded so far with biomolecular systems.