Abstract
Nitrogen-fixing bacteria contain the enzyme nitrogenase that enables them to convert atmospheric nitrogen into ammonia, which can then be used by plants for growth. In a Perspective, [Smith][1] discusses a new structural analysis of the MoFe protein of nitrogenase, which reveals the existence of an interstitial atom in the active site that may be nitrogen. This unexpected finding could help chemists to design a more efficient method for producing ammonia from atmospheric nitrogen. [1]: http://www.sciencemag.org/cgi/content/full/297/5587/1654