Recent developments in the mechanism and application of the catalytic reaction of [NiFe] hydrogenase.

Hydrogenase (H2ase) catalyzes the oxidation of dihydrogen and the reduction of protons with remarkable efficiency, attracting considerable attention in the energy field due to their biotechnological potential. For this simple reaction, [NiFe] H2ase has developed a sophisticated but intricate mechanism with the heterolytic cleavage of dihydrogen, where its Ni-Fe active site exhibits various redox states. Recently, new spectroscopic and crystal structure studies of [NiFe] H2ases have been reported, providing significant insights into the catalytic reaction mechanism, hydrophobic gas-access tunnel, proton transfer pathway, and electron transfer pathway of [NiFe] H2ases. In addition, [NiFe] H2ases have been shown to play an important role in biofuel cell and solar dihydrogen production. This concept provides an overview of the biocatalytic reaction mechanism and biochemical application of [NiFe] H2ases based on the new findings.