Substrate: Nitrogen gas,N2 +2H +2H ⊙0 ⊙⊙ NN ⑧0 Reduction Reduction Nitro- genase Binding of substrate Product: ⊙ Ammonia,NH3 +2H ②國 包⊙ @90o a8996 NN 0 Release of Reduction product Free nitrogenase can bind another molecule of N2 生物固氮生物固氮