Lecture 11 - nitrogen

Nitrogenase

An enzyme in bacteria and archaea that performs nitrogen fixation (converting atmospheric nitrogen into ammonia) . only enzyme that can break the CN triple bond

• diazatroph

• needs a lot of energy

• 2 components: dinitrogenase reductase dinitrogenase

diazatroph

Something that can fix atmospheric nitrogen

dinitrogenase reductase

Electron-delivery compontent of nitrogenase

1. Dinitrogenase reductase (Fe protein) → delivers electrons

2. Dinitrogenase → uses those electrons to fix nitrogen into ammonia

Glutamine synthetase

Converts glutamate to glutamine via ammonia and ATP

Ammonia incorporation

Nitrogen in ammonia assimilates into amino acids (glutamate, glutamine)

Transaminase

Transfers amide from amino acids onto substrates

What is the main point of regulation for ammonia cycling in the cell?

Glutamine synthetase

What regulates glutamine synthetase?

Adenylation of the Tyr at the enzyme’s active site inactivates the enzyme (inhibition)

Essential amino acids

AAs that can only be taken from diet

Nonessential amino acids

AAs that your body can make

• the body uses nitrogen from ammonia to help synthesize nonessential amino acids