The transition metal molybdenum is generally present in these nitrogenases as a MoFe cofactor. Recently, another nitrogenase has been identified in a few cyanobacteria, containing a VFe cofactor.
Hliðarmálmurinn mólýbden er hluti af slíkum nitrogenösum sem MoFe hjálparþáttur en nýlega hefur greinst nitrogenasi sem notar vanadín í stað mólýbdens, sem VFe hjálparþátt.