A Multi-Heme Flavoenzyme as a Solar Conversion Catalyst

The enzyme flavocytochrome c(3) (fcc(3)), which catalyzes hydrogenation across a C=C double bond (fumarate to succinate), is used to carry out the fuel-forming reaction in an artificial photosynthesis system. When immobilized on dye-sensitized TiO2 nanopartides, fcc(3) catalyzes visible-light-driven succinate production in aqueous suspension. Solar-to-chemical conversion using neutral water as the oxidant is achieved with a photo-electrochemical cell comprising an fcc(3)-modified indium tin oxide cathode linked to a cobalt phosphate-modified BiVO4 photoanode. The results reinforce new directions in the area of artificial photosynthesis, in particular for solar-energy-driven synthesis of organic chemicals and commodities, moving away from simple fuels as target molecules.