H₂ production under stress: [FeFe]‑hydrogenases reveal strong stability in high pressure environments

Hydrogenases are a diverse group of metalloenzymes that catalyze the conversion of H₂ into protons and electrons and the reverse reaction. A subgroup is formed by the [FeFe]‑hydrogenases, which are the most efficient enzymes of microbes for catalytic H₂ conversion. We have determined the stability and activity of two [FeFe]‑hydrogenases under high temperature and pressure conditions employing FTIR spectroscopy and the high-pressure stopped-flow methodology in combination with fast UV/Vis detection. Our data show high temperature stability and an increase in activity up to the unfolding temperatures of the enzymes. Remarkably, both enzymes reveal a very high pressure stability of their structure, even up to pressures of several kbars. Their high pressure-stability enables high enzymatic activity up to 2 kbar, which largely exceeds the pressure limit encountered by organisms in the deep sea and sub-seafloor on Earth.