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Modeling a central ligand in the nitrogenase FeMo cofactor
Berit Hinnemann1, Jens K Nørskov
1Center for Atomic-scale Materials Physics (CAMP), Department of Physics, Building 307, Technical University of Denmark, DK-2800 Lyngby, Denmark.
Journal of the American Chemical Society
|February 6, 2003
Summary
Density functional calculations suggest the central ligand in the FeMo cofactor of nitrogenase is nitrogen, not carbon. This finding aligns with recent X-ray crystallographic data.
Area of Science:
- Biochemistry and inorganic chemistry
- Computational chemistry and structural biology
Background:
- The FeMo cofactor is crucial for nitrogenase activity, enabling biological nitrogen fixation.
- A recent X-ray crystallographic study proposed a light atom (N, O, or C) as a central ligand, suggesting it is nitrogen.
Purpose of the Study:
- To computationally investigate the energetic stability and structural viability of nitrogen (N), oxygen (O), and carbon (C) as the central ligand in the FeMo cofactor.
- To compare computational results with experimental crystallographic data to determine the most probable identity of the central ligand.
Main Methods:
- Density functional theory (DFT) calculations were employed to model the FeMo cofactor.
- Energetic stability of different central ligand configurations was assessed.
- Calculated bond geometries were compared with experimentally determined values from X-ray crystallography.
Main Results:
- Density functional calculations indicate that both nitrogen (N) and oxygen (O) can form energetically stable FeMo cofactor structures.
- Carbon (C) was found to be energetically unfavorable as a central ligand.
- Comparison of calculated bond geometries with crystallographic data strongly supports nitrogen as the central ligand.
Conclusions:
- The central ligand in the FeMo cofactor is most likely nitrogen, based on energetic stability and structural geometry.
- Computational modeling provides crucial insights complementing experimental structural data for metalloenzymes.
- This study refines our understanding of the active site structure of nitrogenase, vital for biological nitrogen fixation.
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