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- Title
Site‐Specific Oxidation State Assignments of the Iron Atoms in the [4Fe:4S]<sup>2+/1+/0</sup> States of the Nitrogenase Fe‐Protein.
- Authors
Wenke, Belinda B.; Spatzal, Thomas; Rees, Douglas C.
- Abstract
The nitrogenase iron protein (Fe‐protein) contains an unusual [4Fe:4S] iron‐sulphur cluster that is stable in three oxidation states: 2+, 1+, and 0. Here, we use spatially resolved anomalous dispersion (SpReAD) refinement to determine oxidation assignments for the individual irons for each state. Additionally, we report the 1.13‐Å resolution structure for the ADP bound Fe‐protein, the highest resolution Fe‐protein structure presently determined. In the dithionite‐reduced [4Fe:4S]1+ state, our analysis identifies a solvent exposed, delocalized Fe2.5+ pair and a buried Fe2+ pair. We propose that ATP binding by the Fe‐protein promotes an internal redox rearrangement such that the solvent‐exposed Fe pair becomes reduced, thereby facilitating electron transfer to the nitrogenase molybdenum iron‐protein. In the [4Fe:4S]0 and [4Fe:4S]2+ states, the SpReAD analysis supports oxidation states assignments for all irons in these clusters of Fe2+ and valence delocalized Fe2.5+, respectively.
- Subjects
NITROGENASES; OXIDATION; REARRANGEMENTS (Chemistry); IRON proteins; SULFUR
- Publication
Angewandte Chemie, 2019, Vol 131, Issue 12, p3934
- ISSN
0044-8249
- Publication type
Article
- DOI
10.1002/ange.201813966