Voltammetric behavior of cytochromes c2 and c′ from Rhodospirillum rubrum at an ITO electrode

The direct electrochemical redox behavior of Rhodospirillum rubrum cytochromes c(2) and c(.) could be observed at an ITO electrode pretreated with a few surfactants or with 1 M HNO3. Well-defined redox waves were observed on the voltammograms with + 310 mV of formal redox potential for cyt. c(2) and -15 mV for cyt. c(.), corresponding to a quasireversible one-electron system. The reversible redox reaction of cytochrome c(2) could be observed at a moderately hydrophilic ITO surface, while the highly hydrophilic surface was necessary for cytochrome c(.).