Investigation of the electrode reaction of cytochrome c at self-assembled monolauers

Abstract

Self-Assembled monolayers of carboxyl-terminated alkanethiols, which is negatively charged in pH 7.0, were used to facilitate the electron transfer between the positively charged protein and the electrode. Mercaptoacetic acid, 3-mercapto acetic acid and L-cysteine were investigated as promoters for the electron transfer between cytochrome c and electrode. In case of L-cysteine, as it has both positive and negative group, it can be a candidate for a new modifier to facilitate positively charged protein or negatively charged protein. Our investigation of L-cysteine shows that the electron transfer occurs successfully to both cytochrome c (Cyt c) and pyrroloquinoline quinone (PQQ). The covalent bond is made by 1-ethhy-3-(3-dimethlyaminopropyl carbodiimide (EDC) between Cyt. c and monolayer. Then PQQ was electrostatically adsorbed same monolayer. Cyclic voltammograms show that both molecules do not interfere each other and electron transfer is appreciable.