Now, the enzyme that catalyzes this step is known as a connotase. And this aconitase actually contains an iron sulfur component. And that's why this molecule, the connotase enzyme, is known as an iron sulfur enzyme. An iron sulfur protein now actually contains a ratio of four iron to four sulfur inorganic sulfide atoms. And this complex is found on the active side, and it binds not the hydroxyl onto the carboxylate ion group of the citrate. And that holds the citrate molecules within the active side and allows the catalysis to actually take place.