Biochem 67

Question 1

Leflunomide inhibits which enzyme in nucleic acid synthesis?

Answer 1

Dihydroorotate dehydrogenase

Question 2

Mycophenolate and ribavirin inhibits which enzyme in nucleic acid synthesis?

Answer 2

IMP dehydrogenase

Question 3

Which enzyme is involved in de novo pyrimidine synthesis as well as the urea cycle?

Answer 3

Carbamoyl Phosphate

Question 4

Which enzyme converts ribonucleotides to deoxyribonucelotides?

Answer 4

ribonucleotide reductase

Question 5

Which drug inhibits ribonucleotide reductase?

Answer 5

Hydroxyurea

Question 6

Which drug and its prodrug inhibit de novo purine synthesis?

Answer 6

6-mercaptopurine (6-MP)

Azathioprine (prodrug)

Question 7

Pyrimidine base production requires which amino acid?

Answer 7

Aspartate

Question 8

Pyrimidine base production is initiated with what 2 molecules?

Answer 8

Glutamine + CO2

Question 9

Which drug inhibits thymidylate synthase (leading to dec deoxythymidine monophosphate aka dTMP)

Answer 9

5-Fluorouracil

Question 10

Which drugs inhibit dihydrofolate reductase ( leading to dec dTMP) in:

1) Humans
2) Bacteria
3) Protozoa

Answer 10

1) Methotrexate (MTX)
2) Trimethoprim (TMP)
3) Pyrimethamine