Fehydrogenase

Fehydrogenase is a term used for hydrogenase enzymes in which iron plays a central role in the active site. These enzymes catalyze the reversible interconversion of molecular hydrogen (H2) and protons/electrons, enabling microbial energy metabolism and hydrogen cycling in anaerobic environments. Hydrogenases are divided by metal content into [Fe]-hydrogenases, [FeFe]-hydrogenases, and [NiFe]-hydrogenases. The [Fe]-hydrogenases (often called Hmd) are relatively rare and occur in certain methanogenic archaea; they possess a distinctive iron-centered active site and often a unique iron-containing cofactor. [FeFe]-hydrogenases are more widespread among bacteria and algae and are characterized by a diiron active site coordinated by unusual ligands, enabling efficient H2 uptake and production. [NiFe]-hydrogenases have a nickel-iron active site and also include iron-sulfur clusters that shuttle electrons; despite the name, these enzymes are iron-containing and are commonly studied in environmental microbiology and bioenergy research.

Fehydrogenases function bidirectionally under physiological conditions, converting H2 to protons and electrons or using electrons to reduce protons to H2. Their activity is highly sensitive to oxygen and can be inhibited by reactive oxygen species, which affects their stability in biotechnological applications. In nature, they support anaerobic respiration and fermentation, participate in methane and hydrogen cycles, and contribute to energy conservation in microbial communities.

Research on Fehydrogenases aims to understand mechanism, improve stability, and develop catalytic systems for sustainable hydrogen production, biosensing, and bioelectrocatalysis.