Vanadium(v) is reduced by the ‘as isolated’ nitrogenase Fe-protein at neutral pH

Abstract

Orthovanadate has been investigated in the presence of the nitrogenase Fe-protein. Electron paramagnetic resonance (EPR) spectra demonstrate that vanadium(V) is reduced by the reduced Fe-protein to vanadium(IV) which then probably binds to the nucleotide binding site in place of the Mg²⁺ which is normally present. In contrast, the oxidized Fe-protein is unable to reduce vanadate. In this case vanadate has potential for use as a phosphate analogue where it acts as transition state mimic for hydrolysis.