Ammonia Metabolism

Question 0

Aspartate

Answer 0

Oxaloacetate(TCA cycle intermediate)- donates nitrogen to the urea cycle, can take nitrogen from other aas and donate it directly to a molecule of urea that can be excreted

Question 1

Glutamate

Answer 1

Alpha-ketoglutatate- the direct link between TCA cycle and the amine pool- there is a lot of glutamate in the cell and it usually acts as a nitrogen donor (amino group pool of the cell)

Question 2

Alanine

Answer 2

Pyruvate (involved in many metabolic pathways) - A key role in gluconeogenesis - major transporter of nitrogen to the liver for the urea cycle

Question 3

Glutamine

Answer 3

Glutamate- has 2 amino groups, an important circulating amine pool, transports nitrogen to the liver for urea cycle

Question 4

What three enzymes fix free ammonium?

Answer 4

Glutamate dehydrogenase (oxidizes NADPH to form a carbon bond- one way to make glutamate from alphaketoglutarate), glutamate synthetase (uses ATP to fix an ammonium ion to glutamate in order to form Glutamine) & car amour phosphate synthase (urea cycle)