Pyrimidine Synthesis

Question 1

Who is the precursor amino acid for Pyrimidines?

Answer 1

Aspartate: donates 3C and an amine.

Question 2

Draw the structure of a Pyrimidine with the precursors.

Question 3

What is an amino-acid similarity between Purine and Pyrimidine synthesis.

Answer 3

Glutamine always donates a nitrogen.

Question 4

What is a difference between purine and pyrimidine synthesis?

Answer 4

Aspartate donates its back bone in Purines and pyrimidines. Only pyrimidines keep the whole thing.

Question 5

What is the first step of Pyrimidine synthesis?

Answer 5

Production of Carbamoyl-Phosphate.

Question 6

What is the reaction equation of carbamoyl phosphate synthesis?

Answer 6

Glutamine + CO2 + ATP + ATP = Carbomoyl Phosphate + 2 ADP + pi + Glutamate

The Enzyme is called Carbamoyl Synthetase II

Question 7

What are the other reactions that follow Carbomoyl Phosphate Synthesis?

Answer 7

1. Add aspartate (Condensation).

=Carbamoyl aspartate

2. Close the ring (Remove water)

= Di hydro orotate

3. Oxidation = orotate.
4. Add PRPP = ortidylate
5. Remove CO2 (Decarboxylation) =UMP