Nitrogenase

Nitrogenases are enzymes (EC 1.18.6.1EC 1.19.6.1) that are produced by certain bacteria, such as cyanobacteria (blue-green algae). These enzymes are responsible for the reduction of nitrogen (N2) to ammonia (NH3). Nitrogenases are the only family of enzymes known to catalyze this reaction, which is a key step in the process of nitrogen fixation. Nitrogen fixation is required for all forms of life, with nitrogen being essential for the biosynthesis of molecules (nucleotides, amino acids) that create plants, animals and other organisms. They are encoded by the Nif genes or homologs. They are related to protochlorophyllide reductase.N2 + 8 H+ + 8 e− + 16 MgATP → 2 NH3 + H2 + 16 MgADP + 16 Pi     (1)N2 + 14 H+ + 12 e− + 40 MgATP → 2 NH4+ + 3 H2 + 40 MgADP + 40 Pi     (2) Nitrogenases are enzymes (EC 1.18.6.1EC 1.19.6.1) that are produced by certain bacteria, such as cyanobacteria (blue-green algae). These enzymes are responsible for the reduction of nitrogen (N2) to ammonia (NH3). Nitrogenases are the only family of enzymes known to catalyze this reaction, which is a key step in the process of nitrogen fixation. Nitrogen fixation is required for all forms of life, with nitrogen being essential for the biosynthesis of molecules (nucleotides, amino acids) that create plants, animals and other organisms. They are encoded by the Nif genes or homologs. They are related to protochlorophyllide reductase. The equilibrium formation of ammonia from molecular hydrogen and nitrogen has an overall negative enthalpy of reaction ( Δ H 0 = − 45.2   k J m o l − 1 N H 3 {displaystyle Delta H^{0}=-45.2 mathrm {kJ} ,mathrm {mol^{-1}} ;mathrm {NH_{3}} } ), the activation energy is very high ( E A = 230 − 420   k J m o l − 1 {displaystyle E_{mathrm {A} }=230-420 mathrm {kJ} ,mathrm {mol^{-1}} } ). Nitrogenase acts as a catalyst, reducing this energy barrier such that the reaction can take place at ambient temperatures.