Abstract: The direct electrochemistry of cytochrome C551 from pseudomonas aeruginosa has been investigated at indium-doped tin oxide(ITO) optically transparent electrodes without any surface promoters or mediators. The cyclic voltammograms show a quasi-reversible electrode reaction. Plots of peak reduction current against square root of scan rate are linear over the range 5 mV•s－1 to 100 mV•s－1. The diffusion coefficient of C551 is calculated from the slope of the line. The rate constant for heterogeneous electron transfer is determined by measuring cyclic voltammetry peak separation as a function of scan rate.

Key words: Cytochrome C₅₅₁, ITO electrode, Direct electrochemistry