Nitrogenase is the enzyme of biological nitrogen fixation. The most wide-spread and most efficient nitrogenase contains a molybdenum cofactor. This protein family, AnfK, represents the beta subunit of the iron-only alternative nitrogenase. It is homologous to NifK and VnfK, of the molybdenum-containing and the vanadium (V)-containing types, respectively. [Central intermediary metabolism, Nitrogen fixation]
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