Nitrogenase Enzyme Complex

Question 1

Fixation of nitrogen equation

Answer 1

N2 + 16ATP + 8e- + 8H+ —> 2NH3 + H2 + 16 ADP + 16 Pi

Question 2

Proton donor

Answer 2

Ferrodoxin

Question 3

Nitrate reductase subunits

Answer 3

NO3-

Question 4

Nitrate reductase regulation

Answer 4

Enzyme: protein phosphatase (light + carbohydrates)
Activate: dephosphorylate (OH) serine residue (phosphatase)
Deactivate: phosphorylate Ser-Thr (kinase)

Question 5

NO2- to ammonium

Answer 5

Nitrite reductase

6Fd-red + 8H+ + 6e- makes 2H2O

Question 6

Glutamate to glutamine

Answer 6

Glutamine Synthetase (ATP and cofactor Mg2+)

Question 7

Glutamine to glutamate

Answer 7

Glutamate synthase

2-oxoglutarate + NADH/Fd-red = 2 glutamate

Question 8

2-oxoglutarate to glutamate

Answer 8

Glutamate dehydrogenase (ammonia must be at toxic levels for mammals)
NADPH
makes water

Question 9

Glutamate and oxaloacetate

Answer 9

Aspartate aminotransferase

Aspartate and 2-oxoglutarate

Question 10

Glutamine and aspartate

Answer 10

Asparagine Synthetase
ATP—> AMP
Asparagine and glutamate
Inhibited by light and carbohydrates

Question 11

Nitrogenase enzymes transfer strong e- acceptor O2 to

Answer 11

Heterocysts

-lack photosystem 2