Nitrogen metabolism 1

What is nitrogen fixation?
Biological conversion of atmospheric nitrogen to ammonia (Only carried out in certain bacteria and algae) E.g. rhizobium in legume root nodules
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Describe the nitrogenase complex
A 2 enzyme complex that reduces nitrogen, 2 components (Nitrogenase and nitrogenase reductase), reaction requires ~16ATP and also the reducing power of ferredoxin
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Nitrogenase reductase
(Component 2) Fe-protein, small molecule (4 Fe and 4 S atoms/ molecule), 1 or 2 nitrogenase reductase molecules in a nitrogenase complex, reduced by accepting electrons from ferredoxin, re-oxidised when it passes e's to nitrogenase
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Nitrogenase
Large protein made up of several subunits, reduced by accepting electrons from nitrogenase reductase and is re-oxidised when they are transferred to N2 and H+ to form ammonia
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What is ammonia assimilation?
The incorporation of inorganic nitrogen into organic nitrogen
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What are the 2 routes by which assimilation can take place?
Glutamate dehydrogenase (GDH) and Glutamine synthase (GS)
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Glutamate dehydrogenase
No requirement for ATP, low affinity for NH3, meaning it is almost inactive when NH3 is low, most energetically efficient (most efficient at high NH3 levels)
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Glutamine synthase
Requires ATP, high affinity for NH3, meaning when NH3 is low, it has high activity (Least energetically efficient and most efficient at low NH3 levels
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What is the formula for the GDH reaction?
2-oxo-glutarate + NAHPH+H +NH3 ----> Glutamate + NADP+ +H2O
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What is the formula for the GS reaction?
Glutamate + ATP + NH3 ---> ADP+Pi + Glutamine
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Card 2

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Describe the nitrogenase complex

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A 2 enzyme complex that reduces nitrogen, 2 components (Nitrogenase and nitrogenase reductase), reaction requires ~16ATP and also the reducing power of ferredoxin

Card 3

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Nitrogenase reductase

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Card 4

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Nitrogenase

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Card 5

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What is ammonia assimilation?

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