Molecular Properties and Reaction Mechanism of Multicopper Oxidases Related to Their Use in Biofuel Cells

The multicopper oxidases (MCOs) are a ubiquitous family of proteins that carry out four single-electron oxidations of substrates coupled to the four-electron reduction of dioxygen to water. The combination of solution and electrochemical experiments has the potential to enhance our understanding of the MCOs in general and for biofuel cell applications in particular. Ambiguous redox peaks observed electrochemically might be difficult to assign without direct chemical insight from solution studies. Likewise, chemical effects on MCO activity, including high potential and chloride inhibition, are difficult to interpret only by electrochemistry. The rate-determining step in the organic oxidases is the oxidation of substrate (ET from substrate to T1), which limits the elucidation of fast kinetic processes including intramolecular ET from the T1 to the TNC. Compared to the native enzyme, this could result in new chemistry at the active site that would be inaccessible in solution.