Light-Driven CO₂ Reduction by Co-Cytochrome b ₅₆₂

The current trend in atmospheric carbon dioxide concentrations is causing increasing concerns for its environmental impacts, and spurring the developments of sustainable methods to reduce CO₂ to usable molecules. We report the light-driven CO₂ reduction in water in mild conditions by artificial protein catalysts based on cytochrome b ₅₆₂ and incorporating cobalt protoporphyrin IX as cofactor. Incorporation into the protein scaffolds enhances the intrinsic reactivity of the cobalt porphyrin toward proton reduction and CO generation. Mutations around the binding site modulate the activity of the enzyme, pointing to the possibility of further improving catalytic activity through rational design or directed evolution.