Chemical maturation of hydrogenases : an insight into artificial and biohybrid systems
- Authors
- Publication Date
- Nov 07, 2016
- Source
- Kaleidoscope Open Archive
- Keywords
- Language
- English
- License
- Unknown
- External links
Abstract
There is a general agreement that the building of a sustainable H2 economy relies on the availability of cheap, abundant and efficient catalysts. Nature has provided attractive solutions, hydrogenases. However, these enzymes are difficult to produce and so far only few HydAs have been completely characterized showing diversity despite the same active site. This core, H-cluster, is composed of a [4Fe–4S] cluster bound via a Cys to a diiron complex which has 3 CO, 2 CN and an azadithiolate ligands. Recently, it has been showed that hydrogenases can be easily produced through the insertion of a biomimetic [Fe2(adt)(CO)4(CN)2]2– complex inside the heterologously produced apo-enzyme, resulting in a full activation. Part of the PhD has been focused on the chemical maturation of new HydA from Megasphaera elsdenii and its truncated version, MeH-HydA, containing only the H-cluster. The assembly of all metal cofactors via the chemical reconstitution of the [Fe–S] clusters and the maturation through the [Fe2(adt)(CO)4(CN)2]2–complex has been carried out. Interestingly, HydF hybrids synthesized incorporating biomimetic [Fe2(xdt)(CO)4(CN)2]2– complexes onto the [4Fe–4S] cluster HydF protein, have a 6Fe core reminiscent of the H-cluster. HydFs from different organisms were purified and subsequently the [4Fe–4S] cluster has been reconstituted. For the first time, an X-ray structure of HydF with its [4Fe-4S] cluster has been obtained. The 6Fe cluster of HydF has been also prepared chemically with diiron complexes mimicking the active site of HydA. The metallo-cofactors have been spectroscopically characterized (EPR, FTIR, HYSCORE), hydrogenase activities evaluated.
