Nitrogen Metabolism Overview
Terms in this set (41)
inert gas, unreactive, not biologically useful.
What's the problem with N2 reduction into 2NH3
it's energetically favorable by has a crazy high activation energy
Haber Process Conditions
500 0C; 300 psi; Fe catalyst; 225 kcal/mol
Where does all nitrogen come from in the cell?
Nitrogen goes from the environment into Glutamine and Glutamate
What does Nitrogen Fixation, nitrification, and denitrification have in common?
They are REDOX reactions
where nitrogen in fixed in plants
What does almost all NH3 become?
NO2- , converted by soil bacteria, a good fertilizer
How is Rhizobium and a plant in true symbiosis?
The bacteria fixes N2 for the plant, and creates heme group for leghemoglobin. The plant supplies ATP for enzyme use and produces the leghemoglobin
Difference leghemoglobin and hemoglobin
It binds O2 ten times stronger, effectively creating an anaerobic environment
REDOX Nitrogen Fixation
N2 + 8H+ +8e- + 16ATP ---> 2NH3 + H2 + 16ADP
Reduction of nitrogen
nitrogen-->diimine-->hydrazine-->Ammonia (2 e- and 2 H+ added each step)
Dimer of dimers
What does each reduction reaction require in Nitrogenase complex?
2 ATP must be hydrolysized per 1 e- transfer
What are the 3 possible fates of N2 ad NH3?
3)Carbamoyl phosphate (Urea cycle)
Uses NADPH from a-ketoglutarate and NH4+ with glutamatease dehydrgenase
From Glutamate and NH4+, uses ATP and glutamine synthetase
6 Amino Acid families
glutamate, Aspartate, Serine, Pyruvate, Aromatic, Histidine
Glutamate family carbon skeleton
Aspartate family carbon skeleton
serine family carbon family
Pyruvate family carbon skeleton
Aromatic carbon family
histidine carbon family
How can you determine an essential or non-essential amino acid?
diet restriction experiment by removing 1 Amino Acid from the diet each time
PLP (pyridoxal phosphate)
When is the nitrogen donated directly from Glu
high concentration of ammonia
When is nitrogen donated from Gln
Occurs in low concentration ammonia
How can organisms get rid of ammonia?
Organisms that secrete ammonia
Amoniotellic orgnaisms (fish+aquatics)
Organisms that secrete uric acid
Uriotellic organisms (non-toxic, birds)
Organisms that secrete urea
Carbamoyl Phosphate Synthesis
Carbonate and NH3 combined with ATP through Carbamoyl Phosphate synthetase
Start and end molecule
Where do the nitrogen come from in urea
1 each from carbamoyl phosphate and Aspartate
Where does the Urea cycle occur?
Mostly in the cytosol of liver cells, but aspartate and citrulline come from the mitrochondrial matrix.
formed from ornithine and carbomyl phosphate