Metalloprotein mimics – old tools in a new light

• Hydrogenases and nitrogenases generate hydrogen and ammonium under ambient conditions.
• Chemical mimics of the hydrogenase cofactor fully restore hydrogenase activity.
• Design of mimics and scaffolds helps to develop new artificial biocatalysts.

Metalloproteins utilize metal cofactors to catalyze essential reactions in all organisms. They carry out thermodynamically challenging substrate conversions such as the oxidation of water or hydrocarbons, the reduction of nitrogen to ammonium, and generation of molecular hydrogen. Besides their fundamental role in nature, metalloenzymes have promising biotechnological applications that aim to generate high-value chemicals, drugs, nutrients, biofuels, or electricity. Recent reports that a chemically synthesized compound is able to reconstitute [2Fe]-hydrogenases, harboring an especially elaborate and highly efficient metal cofactor, promise to pave the way for gaining much deeper insight into the function of even complex metal enzymes. What is more, synthetic biology approaches such as the chemical synthesis of artificial hydrogenases seem to be in reach.