Tornheim NT Mechanisms

Question 1

Carbamoyl-P Synthase II: Inhibitors and which step?

Answer 1

Inhibited by products of the pyrimidine synthesis pathway
- First step of the pyrimidine synthesis pathway

Question 2

CP Syn 2 and Aspartate Transcarbamoylase are both activated by which compound?

Answer 2

ATP

Question 3

Aspartate Transcarbamoylase: Inhibitors and which step?

Answer 3

Inhibited by CTP
- Second step of pyrimidine synthesis pathway

Question 4

Dihydrofolate Reductase: Inhibitors and which step?

Answer 4

Inhibited by Aminopterin, Amethopterin (Methotrexate)
- First step in reducing Dihydrofolate to Trihydrofolate

Question 5

Thymidylate Synthase: Inhibitors and which step?

Answer 5

F-dUMP from Fluorouracil, Fluorodeoxyuridine
- Converts dUMP to dTMP

Question 6

The AMP branch of purine synthesis uses which amino acid?

Answer 6

Aspartate

Question 7

The GMP branch of purine synthesis uses which amino acid?

Answer 7

Glutamine -> Glutamate

Question 8

Glutamine is used how many times in purine and pyrimidine synthesis and in which steps?

Answer 8

5 times
- PRPP to 5-phosphoribosylamine
- 5-phosphoribosylamine to IMP
- XMP to GMP
- 2 ATP, CO2, Glutamine to Carbamoyl-P
- UTP to CTP

Question 9

Aspartate is used how many times in purine and pyrimidine synthesis, and which steps?

Answer 9

3 times
- 5-phosphoribosylamine to IMP
- IMP to Adenylosuccinate
- Carbamoyl-P to Carbamoyl-Aspartate

Question 10

How many CO2 does the production of CTP produce?

Answer 10

1, right after creation of OMP

Question 11

When is PRPP added in pyrimidine synthesis?

Answer 11

Combined with Orotate to create OMP

Question 12

What amino acid is consumed to produce N10-MTHF in dTMP synthesis?

Answer 12

Serine, used to produce Glycine

Question 13

Site 1 of Ribonucleotide Reductase is inhibited by the binding of which compound?

Answer 13

dATP, NOT ATP

Question 14

Site 2 of Ribonucleotide Reductase regulation