Nitrogenase (Component I)

The enzyme system responsible for N 2 reduction, called the nitrogenase complex, consists of two separate proteins. As outlined in Figure 20.4, one protein-called component I, nitrogenase, or molybdenumiron protein-catalyzes the reduction of N 2, and the other-called component II, nitrogenase reductase, or iron protein-transfers electrons from ferredoxin or flavodoxin to component I. Both component I and component II contain Fe 4S 4 iron-sulfur clusters, and component I also contains molybdenum, in the form of a tightly bound iron-molybdenum cofactor (FeMoCo).

See also: Metalloenzymes, Nitrogenase, Nitrogen Fixation, Figure 20.2, Ferredoxin, Nitrogen Fixation, Nitrogenase Reductase