Electron Transfer and Nano-Scale Motions in Nitrogenase Fe-Protein

During biological nitrogen fixation, the nitrogenase Fe-protein containing the [4Fe-4S] metal cluster has been shown to function in electron transfer to the MoFe-protein. This function of the Fe-protein is dependent on its conformational state and the metal cluster of the active site. This review will summarize the structures of the nucleotide bound (or "off") and amino-acid-substituted Fe-protein as well as the properties of the metal cluster in Fe-protein. The conformational changes in the nucleotide-dependent switch regions increase the driving force, leading to intermolecular electron transfer and macromolecular complex formation from the [4Fe-4S] metal cluster of the Fe-protein to the substrate reduction site of the MoFe-protein.