The nitrogenase complex The dinitrogenase reductase(dimer The dinitrogenase reducto dimer) st oike dinitrogenase (tetramer) Fe-Mo cofactor ADP 4Fe-4s CHa CHa 4Fe-4S HO-C-COO 4Fe-4S ADP COO (P-cluster) Homocitrate
The nitrogenase complex The dinitrogenase (tetramer) The dinitrogenase reductase (dimer) The dinitrogenase reductase (dimer) ADP ADP 4Fe-4S 4Fe-4S 4Fe-4S (P-cluster) Fe-Mo cofactor
2. Electrons are transferred through a series- of carriers to 2 r its reduction on the nitrogenase complex Eight electrons are believed to be needed for each round of fixation reaction: with six for reducing one n2 and two for reducing 2 H** (to form H2) The electrons mainly come from reduced ferredoxin(from photophosphorylation) or reduced flavodoxin(from oxidative ph hosphorylation) and are transferred to dinitrogenase via dinitrogenase reductase
2. Electrons are transferred through a series of carriers to N2 for its reduction on the nitrogenase complex • Eight electrons are believed to be needed for each round of fixation reaction: with six for reducing one N2 and two for reducing 2 H+ (to form H2 ). • The electrons mainly come from reduced ferredoxin (from photophosphorylation) or reduced flavodoxin (from oxidative phosphorylation) and are transferred to dinitrogenase via dinitrogenase reductase
For each electron to be transferred from dinitrogenase reductase to dinitrogenase, two ATPs are hydrolyzed causing a conformational change which reduces the electron affinity for the reductase (i.e, an increased reducing power) The oxidized and reduced dinitrogenase reductase dissociates from and associates with the dinitrogenase, respectively The overall reaction catalyzed is N,+8H++8+16ATP+16H,O 2NH +H+16ADP+16P
• For each electron to be transferred from dinitrogenase reductase to dinitrogenase, two ATPs are hydrolyzed causing a conformational change which reduces the electron affinity for the reductase (i.e., an increased reducing power). • The oxidized and reduced dinitrogenase reductase dissociates from and associates with the dinitrogenase, respectively. • The overall reaction catalyzed is: • N2 + 8H+ +8e - + 16ATP + 16H2O → • 2NH3 + H2 + 16ADP + 16Pi