Abstract
The mechanism of the reduction of the hydrated uranyl cation, [UO 2]2+, by the cytochromes G. sulfurreducens and D. acetoxidans has been studied using density functional theory calculations. We propose that the initial electron transfer step from the heme is to a cation-cation complex in the case of D. acetoxidans, but for G. sulfurreducens, it is to a single uranyl cation, which then forms a U(V)-U(VI) complex with a second uranyl cation. For both enzymes, the subsequent catalytic pathways are very similar. A U(V)-U(V) complex is formed, which then undergoes disproportionation via two successive protonation steps of one uranyl group, to give a U(VI)-U(IV) complex which dissociates to individual U(VI) and U(IV) species, the former being bound at the enzyme active site. Intermediate structures along the catalytic pathway are consistent with EXAFS data. © 2008 American Chemical Society.
Original language | English |
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Pages (from-to) | 4451-4457 |
Number of pages | 6 |
Journal | Journal of Physical Chemistry A |
Volume | 112 |
Issue number | 19 |
DOIs | |
Publication status | Published - 15 May 2008 |
Keywords
- EFFECTIVE CORE POTENTIALS
- AUTOMATED DOCKING
- ELECTRON-TRANSFER
- AQUO
- COMPLEXES
- FREE-ENERGY
- CHEMISTRY
- URANIUM
- COORDINATION
- ION
- CARBONATE