Hydrogenase: Structure, Function, Maturation, and Application

Book excerpt: Molecular hydrogen (H2) is an important molecule in the metabolism of diverse microorganisms. It is used either as energy source or for the disposal of reducing equivalents depending on environmental conditions. Furthermore, H2 transmits energy between different species within microbial communities. The enzymes that split or evolve H2 are called hydrogenases and these metalloproteins can be divided into three phylogenetically unrelated classes distinguishable by the metal composition of their active sites, namely [Fe]-, [FeFe]-, and [NiFe]- hydrogenases. Following a century of hydrogenase research, it is now possible to isolate, handle, and investigate these fragile enzymes. There have been numerous advances in understanding the regulation, function, structures, and maturation of these enzymes, as well as their involvement in important processes such as microbial pathogenesis and biogeochemical cycling. The employment of hydrogenases and hydrogenase-based applications could also potentially facilitate the world’s transition to a future sustainable H2-based energy economy.