Electrochemistry at the tetrathiafulvalene tetracyanoquinodimethane electrodes. Application to the study of c-type cytochromes

Electrodes made from pastes of the conducting organic sail, tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ), are prepared and characterized using electrochemical techniques. These electrodes behave as conventional solid electrodes within their stable potential range. An attractive property is their capability to achieve direct electrochemistry of c-type cytochromes (horse heart cytochrome c, cytochrome c(552) from Thiobacillus ferrooxidans). Results on pH-dependence and kinetic data for these metalloproteins agree with previously published data. It is suggested that favorable interactions occur between the TTF-TCNQ electrode surface and redox protein sites. Moreover, the analytical advantage of using permselective-membrane TTF-TCNQ electrode is demonstrated.