Direct Wiring of Cytochrome c's Heme Unit to an Electrode:  Electrochemical Studies

A novel strategy for the immobilization of cytochrome c on the surface of chemically modified electrodes is demonstrated and used to investigate the protein's electron-transfer kinetics. Mixed monolayer films of alkanethiols and omega-terminated alkanethiols (terminated with pyridine, imidazole, or nitrile groups that are able to ligate with the heme) are used to adsorb cytochrome c to the surface of gold electrodes. The use of mixed films, as opposed to pure films, allows the concentration of adsorbed cytochrome to remain dilute and ensures a higher degree of homogeneity in their environment. The adsorbed protein is studied using electrochemical methods and scanning tunneling microscopy.