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Title: Localized Electronic Structure of Nitrogenase FeMoco Revealed by Selenium K-Edge High Resolution X-ray Absorption Spectroscopy

Journal Article · · Journal of the American Chemical Society
ORCiD logo [1]; ORCiD logo [1];  [2];  [3];  [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [1]
  1. Max Planck Inst. for Chemical Energy Conversion, Mülheim (Germany)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States). Photon Ultrafast Laser Science and Engineering Inst. (PULSE)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States).
  4. PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
  5. California Inst. of Technology (CalTech), Pasadena, CA (United States). Div. o Chemistry and Chemical Engineering

The size and complexity of Mo-dependent nitrogenase, a multicomponent enzyme capable of reducing dinitrogen to ammonia, have made a detailed understanding of the FeMo cofactor (FeMoco) active site electronic structure an ongoing challenge. Selective substitution of sulfur by selenium in FeMoco affords a unique probe wherein local Fe-Se interactions can be directly interrogated via high-energy resolution fluorescence detected X-ray absorption spectroscopic (HERFD XAS) and extended X-ray absorption fine structure (EXAFS) studies. These studies reveal a significant asymmetry in the electronic distribution of the FeMoco, suggesting a more localized electronic structure picture than is typically assumed for iron-sulfur clusters. Supported by experimental small molecule model data in combination with time dependent density functional theory (TDDFT) calculations, the HERFD XAS data is consistent with an assignment of Fe2/Fe6 as an antiferromagnetically coupled diferric pair. HERFD XAS and EXAFS have also been applied to Se-substituted CO-inhibited MoFe protein, demonstrating the ability of these methods to reveal electronic and structural changes that occur upon substrate binding. These results emphasize the utility of Se HERFD XAS and EXAFS for selectively probing the local electronic and geometric structure of FeMoco.

Research Organization:
Max Planck Institute for Chemical Energy Conversion, Mülheim (Germany)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC02-76SF00515
OSTI ID:
1557383
Alternate ID(s):
OSTI ID: 1559864
Journal Information:
Journal of the American Chemical Society, Vol. 141, Issue 34; ISSN 0002-7863
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 40 works
Citation information provided by
Web of Science

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Cited By (4)


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