Details

Autor(en) / Beteiligte

• Van Stappen, Casey
• Thorhallsson, Albert Thor
• Decamps, Laure
• Bjornsson, Ragnar
• DeBeer, Serena

Titel

Resolving the structure of the E1 state of Mo nitrogenase through Mo and Fe K-edge EXAFS and QM/MM calculations† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c9sc02187f

Ist Teil von

• Chemical science (Cambridge), 2019-09, Vol.10 (42), p.9807-9821

Ort / Verlag

Royal Society of Chemistry

Erscheinungsjahr

2019

Link zum Volltext

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• The FeMoco cluster of Mo nitrogenase undergoes minor distortions upon reduction to E 1 , supporting iron-based reduction and belt sulfide protonation. Biological nitrogen fixation is predominately accomplished through Mo nitrogenase, which utilizes a complex MoFe 7 S 9 C catalytic cluster to reduce N 2 to NH 3 . This cluster requires the accumulation of three to four reducing equivalents prior to binding N 2 ; however, despite decades of research, the intermediate states formed prior to N 2 binding are still poorly understood. Herein, we use Mo and Fe K-edge X-ray absorption spectroscopy and QM/MM calculations to investigate the nature of the E 1 state, which is formed following the addition of the first reducing equivalent to Mo nitrogenase. By analyzing the extended X-ray absorption fine structure (EXAFS) region, we provide structural insight into the changes that occur in the metal clusters of the protein when forming the E 1 state, and use these metrics to assess a variety of possible models of the E 1 state. The combination of our experimental and theoretical results supports that formation of E 1 involves an Fe-centered reduction combined with the protonation of a belt-sulfide of the cluster. Hence, these results provide critical experiment and computational insight into the mechanism of this important enzyme.