title: Probing the effects of one-electron reduction and protonation on the electronic properties of the Fe-S clusters in the active-ready form of [FeFe]-hydrogenases. A QM/MM investigation.
abstract: A QM/MM investigation of the active-ready (H(ox)) form of [FeFe]-hydrogenase from D. desulfuricans, in which the electronic properties of all Fe-S clusters (H, F and F') have been simultaneously described using DFT, was carried out with the aim of disclosing a possible interplay between the H-cluster and the accessory iron-sulfur clusters in the initial steps of the catalytic process leading to H(2) formation. It turned out that one-electron addition to the active-ready form leads to reduction of the F'-cluster and not of the H-cluster. Protonation of the H-cluster in H(ox) is unlikely, and in any case it would not trigger electron transfer from the accessory Fe(4)S(4) clusters to the active site. Instead, one-electron reduction and protonation of the active-ready form trigger electron transfer within the protein, a key event in the catalytic cycle. In particular, protonation of the H-cluster after one-electron reduction of the enzyme lowers the energy of the lowest unoccupied molecular orbitals localized on the H-cluster to such an extent that a long-range electron transfer from the F'-cluster towards the H-cluster itself is allowed.
authors.affiliation: Department of Biotechnology and Biosciences, University of Milan-Bicocca, Piazza della Scienza, 2-20126 Milan, Italy. claudio.greco@unimib.it
authors.forename: Claudio
authors.initials: C
authors.lastname: Greco
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bruschi
authors.forename: Piercarlo
authors.initials: P
authors.lastname: Fantucci
authors.forename: Ulf
authors.initials: U
authors.lastname: Ryde
authors.forename: Luca
authors.initials: L
authors.lastname: De Gioia
mesh_terms: D055162:Biocatalysis; D020134:Catalytic Domain; D045285:Desulfovibrio desulfuricans / Q000201:enzymology; D004583:Electrons; D006859:Hydrogen / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011522:Protons; D011789:Quantum Theory; D013455:Sulfur / Q000737:chemistry*
chemical_list: D007506:Iron-Sulfur Proteins; D011522:Protons; D013455:Sulfur; D006859:Hydrogen; D007501:Iron; C118830:iron hydrogenase; D006864:Hydrogenase