Characterization of isolated nitrogenase FeVco

Area of Science:

• Biochemistry
• Bioinorganic Chemistry
• Enzymology

Background:

• Nitrogenases catalyze essential nitrogen fixation. Vanadium-nitrogenase cofactors (FeVco) are homologous to molybdenum-nitrogenase cofactors (FeMoco) but have distinct catalytic roles.
• Previous isolation of FeVco lacked full catalytic activity, limiting mechanistic studies.
• Azotobacter vinelandii is a key organism for nitrogenase research.

Purpose of the Study:

• To isolate and characterize a fully active FeVco species from A. vinelandii.
• To compare the structural and electronic properties of FeVco with FeMoco.
• To establish a foundation for future investigations into FeVco's catalytic mechanism.

Main Methods:

• Isolation and purification of FeVco from A. vinelandii.
• Metal analysis and enzyme activity assays (C2H2 reduction, N2 fixation).
• Electron Paramagnetic Resonance (EPR) and X-ray Absorption Spectroscopy (XAS/EXAFS) for structural and electronic characterization.

Main Results:

• Successfully isolated a fully active FeVco species capable of N2 reduction to NH3.
• FeVco demonstrated catalytic activity in reducing C2H2 to C2H6.
• EPR and XAS/EXAFS data revealed FeVco is similar to, yet distinct from, FeMoco in electronic properties and structure.

Conclusions:

• The isolation of fully active FeVco provides a crucial tool for studying nitrogen fixation.
• The findings suggest FeVco's unique electronic and structural properties dictate its distinct reactivity compared to FeMoco.
• This study presents the first EXAFS-based structural model of isolated FeVco, paving the way for future research.