Nitrogen
Occurrence: 1. ~ 80% atmosphere 2. NaNO 3 salpeter 3. Living: 1,4% (human body)
Nitrogen fixation N N 940 kJ/mol N 2 N e kJ/mol 1.Chemical: - Haber-Bosch: N H 2 - Mild conditions:- large amount of red. agent - non-aqueous conditions 500°C 250 atm 2 NH 3
Nitrogen fixation 2.Biological fixation PROKARYIOTS other living syst. Higher animals (humans)
Biological Nitrogen Comes from N kg of N 2 fixed annually
*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.
*Nitrogen Fixation and Nitrogenase
1. Nitrogenase: dinitrogenase mol ATP reductase 2.Ferredoxin (electron carrier!) Mo - Fe - protein+2 Fe - protein NITROGENASE
FeMo co complex
Nitrogen Fixation electron donors vary ATP hydrolysis required H 2 generated as a by-product FeMo Cluster
Nitrogenase Mechanism
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 - +