Only certain microbes, armed with enzymes called nitrogenases, can split nitrogen and convert it into ammonia, a form essential for life. There are three classes of nitrogenases, distinguished by the metals they contain: molybdenum (Mo), vanadium (V), or iron (Fe). Instead, it helps nearby iron atoms grip nitrogen more tightly, making it easier to start breaking the nitrogen-nitrogen triple bond. In the first study, led by Tong Wu and Madeleine Ehweiner, researchers swapped different metals into simplified iron-sulfur clusters. The influence of heterometals on dinitrogen binding at synthetic iron-sulfur clusters.