Structural insights into the catalysis of the [FeFe] hydrogenase from Desulfovibrio desulfuricans
Ingrid Span1, Konstantin Bikbaev1, James Birrell2, Maria Martini2
1Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany,
2Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr, Germany
Hydrogen is considered to be an ideal primary energy carrier for a future society based on renewable energy due to its high energy density and clean combustion. At present H2 is produced mostly from fossil fuels or by water electrolysis using expensive noble metal catalysts. Nature has provided us with a series of enzymes that efficiently produce hydrogen with active sites containing only Fe or Ni and Fe. [FeFe] hydrogenases are the most active H2-converting catalysts in nature, but their extreme oxygen sensitivity is a major problem still to overcome. The [FeFe] hydrogenases from the sulfate-reducing bacterium Desulfovibrio desulfuricans (DdHydAB) is the most active H2-producing bio-catalyst, and it can be isolated in an O2-stable, inactive state called Hinact. We have obtained insights into the mechanism of O2- protection, the activation of the Hinact state, the catalytic mechanism of DdHydAB, and its inhibition by CO using a combination of X-ray crystallography and spectroscopy. Our results provide snapshots of the enzyme in different states and contribute to a better understanding of the function of [FeFe] hydrogenases.