1. Nitrogen

2.  Occurrence: 1. ~ 80% atmosphere 2. NaNO 3 salpeter 3. Living: 1,4% (human body)

3. Nitrogen fixation N N 940 kJ/mol N 2  N 2 + + e - 1500 kJ/mol 1.Chemical: - Haber-Bosch: N 2 + 3 H 2 - Mild conditions:- large amount of red. agent - non-aqueous conditions 500°C 250 atm 2 NH 3

4. Nitrogen fixation 2.Biological fixation PROKARYIOTS other living syst. Higher animals (humans)

5. Biological Nitrogen Comes from N 2 10 11 kg of N 2 fixed annually

6. *Nitrogen Fixation and Nitrogenase *The fixed nitrogen (NH 3, NO 2 -, and NO 3 - ) is consumed by plants and then eaten by animals. *Animal waste and dead plants are attacked by bacteria that break down the fixed nitrogen and produce N 2 gas for the atmosphere.

7. *Nitrogen Fixation and Nitrogenase

8. 1. Nitrogenase: dinitrogenase12 - 14 mol ATP reductase 2.Ferredoxin (electron carrier!) Mo - Fe - protein+2 Fe - protein NITROGENASE

9. FeMo co complex

11. Nitrogen Fixation electron donors vary ATP hydrolysis required H 2 generated as a by-product FeMo Cluster

12. Nitrogenase Mechanism

13. Ch 19http://astro.temple.edu/~keyer13 The Nitrogen Cycle Atmospheric nitrogen Atmospheric fixation and deposition Animal manures and biosolids Industrial fixation (commercial fertilizers) Crop harvest Volatilization Denitrification Runoff and erosion Leaching Organic nitrogen Ammonium (NH 4 ) Nitrate (NO 3 ) Plant residues Biological fixation by legume plants Plant uptake Immobilization Mineralization Input to soil Component Loss from soil - +