Moving towards the biological production of H2
Structure of the metal-based catalytic centre
Oeiras, 03.03.10
While certainly an attractive alternative, the biological production of hydrogen has been hampered by the high sensitivity of hydrogenases – the enzymes catalyzing the production of H2 – to oxygen. ITQB researchers from the Bacterial Energy Metabolism Lab, the Industry and Medicine Applied Crystallography Lab, and the Protein Modeling Lab have been working on a highly active bacterial hydrogenase that exhibits an increased tolerance to oxygen inactivation. The crystal structure of the [NiFeSe] hydrogenase from Desulfovibrio vulgaris Hildenborough in the oxidized state, now published in Journal of Molecular Biology, exposes the molecular basis for its oxygen tolerance.
The promise of a hydrogen-based economy requires the production of hydrogen from renewable sources but the seemingly simple reaction of producing H2 from water is actually very difficult to achieve. Conversely, nature has devised extremely efficient enzymes for the production and oxidation of H2 in ambient conditions. These hydrogenases contain a complex metal-based catalytic cofactor deeply buried within the protein and are vital for anaerobic metabolism. The technological application of hydrogenases is, however, held back because oxygen is able to react with the catalytic centre, inactivating the enzyme. The inactivation is irreversible for [FeFe] hydrogenases but reversible for [NiFe] hydrogenases, which for this reason become more attractive for hydrogen production strategies.
Analyzing the crystal structure of [NiFeSe] hydrogenase from Desulfovibrio vulgaris Hildenborough in the oxidized state, researchers found that a sulfur atom bound to the selenocysteine that is a ligand to the Ni prevents oxygen from reaching and inactivating the NiFe site. This is the first example of a hydrogenase from the [NiFe] family that in its oxidized state does not contain an oxygen species bound to its active site. The results now published represent an important step towards engineering more robust enzymes / microorganisms or developing biomimetic catalysts for hydrogen production.
Original Article
J. Mol. Biol. (2010) 396, 893–907
The Three-Dimensional Structure of [NiFeSe] Hydrogenase from Desulfovibrio vulgaris Hildenborough: A Hydrogenase without a Bridging Ligand in the Active Site in Its Oxidised, “as-Isolated” State
Marta C. Marques, Ricardo Coelho, Antonio L. De Lacey,Inês A. C. Pereira and Pedro M. Matias
