vnfG Nitrogenase vanadium-iron protein delta chain Nitrogenase component I 113 Dinitrogenase 2 subunit delta The key enzymatic reactions in nitrogen fixation are catalyzed by the nitrogenase complex, which has 2 components: the iron protein (component 2) and a component 1 which is either a molybdenum-iron protein, a vanadium-iron, or an iron-iron protein. VNFG_AZOVI MSQSHLDDLFAYVEERCLWQFFSRTWDREENIEGVLNQVGRLLTGQEPLRGTPQERLFYADALAMANDVRERFPWASQVNKEEIEFLLDGLKSRLVDVTITRSTNRELNHHLY