Dinitrogen reduction by nitrogenase: if N2 isn't broken, it can't be fixed

Nitrogenase consists of two component metalloproteins, the iron protein and molybdenum-iron protein, which together catalyze the ATP-dependent reduction of dinitrogen to ammonia during biological nitrogen fixation. With the recent crystal structure determinations of both proteins, a structural framework is now available for interpreting the mechanism of nitrogenase at the molecular level.