Electrochemical characterization of molecular orientation effect on self-assembled recombinant ferredoxin

Electrochemical characterization of the modified ferredoxin was performed on a gold electrode. The genetically modified ferredoxin containing iron–sulfur cluster was immobilized by two kinds of different molecular interaction (Au–thiol and electrostatic interaction), respectively. The change of molecular configuration was investigated with the estimated thickness of the fabricated thin film as function of applied concentration and atomic force microscopy (AFM). Oxidation–reduction of the immobilized ferredoxin was dependent on its molecular configuration on the electrode, which was considered due to the distance of the redox center from the electrode. When the modified ferredoxin was immobilized by means of electrostatic interaction on l-cysteine monolayer, well-ordered molecular configuration could be observed with AFM. Cyclic voltammetry showed that the redox potential of the immobilized ferredoxin has a formal midpoint potential of −300 mV (versus Ag/AgCl). Experiment results showed that the recombinant ferredoxin could be worked out for electron transfer with redox center close to electrode and pinhole free surface structure.