Fe is an important component of enzymes

Fe is an important component of all the given enzymes that are nitrogenase, nitrate reductase, and nitrite reductase. All these are enzymes responsible for nitrogen fixation.
Iron is an essential cofactor for a variety of redox reactions in plant metabolism and Fe requires enzymes to catalyze reactions that also involve oxygen, as a reagent or product of the reaction itself or as an entry or end point a metabolic pathway.