Secondary structure changes as the potential H sensing mechanism of group D [FeFe]-hydrogenases.

[FeFe]-hydrogenases function as both H catalysts and sensors. While catalysis is well investigated, details regarding the H sensing mechanism are limited. Here, we relate protein structure changes to H sensing, similar to light-driven bio-sensors.

Kinetic Modeling of the Reversible or Irreversible Electrochemical Responses of FeFe-Hydrogenases.

The enzyme FeFe-hydrogenase catalyzes H evolution and oxidation at an active site that consists of a [4Fe-4S] cluster bridged to a [Fe(CO)(CN)(azadithiolate)] subsite. Previous investigations of its mechanism were mostly conducted on a few "prototypical" FeFe-hydrogenases, such as that from (Cr HydA1), but atypical hydrogenases have recently been characterized in an effort to explore the diversity of this class of enzymes. We aim at understanding why prototypical hydrogenases are active in either direction of the reaction in response to a small deviation from equilibrium, whereas the homologous enzyme from (Tam HydS) shows activity only under conditions of very high driving force, a behavior that was referred to as "irreversible catalysis".

Novel concepts and engineering strategies for heterologous expression of efficient hydrogenases in photosynthetic microorganisms.

Hydrogen is considered one of the key enablers of the transition towards a sustainable and net-zero carbon economy. When produced from renewable sources, hydrogen can be used as a clean and carbon-free energy carrier, as well as improve the sustainability of a wide range of industrial processes. Photobiological hydrogen production is considered one of the most promising technologies, avoiding the need for renewable electricity and rare earth metal elements, the demands for which are greatly increasing due to the current simultaneous electrification and decarbonization goals.