Redox enzymes catalyse oxidation or reduction reactions in biological systems with unrivalled selectivity and efficiency. The design features embedded within the enzyme active site act to both select a specific substrate and activate the substrate for a redox reaction. Enzyme electrochemistry harnesses these ideal catalytic properties while providing the fuel for the reaction via an electrical current. In this proposal we aim to improve on Nature by stripping back all accessory redox cofactors from sulfite oxidising enzymes to leave the active site domain alone to carry out its function. This novel approach will for the first time define the minimal amount of redox machinery that is required for electrochemical catalytic function.