Mechanistic features of the Mo-containing nitrogenase

Nitrogenase is the complex metalloenzyme responsible for biological dinitro gen reduction. This reaction represents the single largest contributor to t he reductive portion of the global nitrogen cycle. Recent developments in u nderstanding the mechanism of the Mo-based nitrogenase are reviewed. Topics include how nucleotide binding and hydrolysis are coupled to electron tran sfer and substrate reduction, how electrons are accumulated and transferred within the MoFe-protein, and how substrates bind and are reduced at the ac tive site metal cluster.