Enzymes FTM 2

Question 1

PRPP Synthetase

Answer 1

Synthesis of PRPP for purine and pyrimidine nucleotide synthesis

Question 2

Phosphoribosyl Amidotransferase

Answer 2

Regulated/committed enzyme of purine nucleotide synthesis; Activators: PRPP; inhibitors: ATP and GTP

Question 3

Xanthine oxidase

Answer 3

Enzyme of purine degradation; forms uric acid from xanthine; Also forms xanthine from hypoxanthine; Inhibitor: Allopurinol

Question 4

HGPRT

Answer 4

Enzyme of Purine salvage pathway; Deficiency causes Lesch Nyhan syndrome

Question 5

CPS-II

Answer 5

Regulated enzyme of pyrimidine biosynthesis (Inhibited by UTP; Activated by PRPP); Cytosolic enzyme

Question 6

UMP Synthase (OPRT and OMP decarboxylase)

Answer 6

Enzyme of pyrimidine biosynthesis; deficiency of the enzyme results in Orotic aciduria

Question 7

Ribonucleotide reductase

Answer 7

Converts ribonucleotides to deoxyribonucleotides; Inhibitor: Hydroxyurea

Question 8

Thymidylate synthase

Answer 8

Forms dTMP from dUMP for DNA synthesis

Inhibitors: 5-Fluorouracil, methotrexate (dihydrofolate reductase inhibitor)

Question 9

Sulfa Drugs (sulfonamides)

Answer 9

Inhibit bacterial folate synthesis from PABA

Question 10

Trimethoprim

Answer 10

Inhibit bacterial dihydrofolate reductase

Question 11

Methotrexate

Answer 11

Inhibit eukaryotic dihydrofolate reductase (used as an anticancer agent)

Question 12

Hydroxyurea

Answer 12

Inhibits ribonucleotide reductase (this enzyme converts ribonucleotides to deoxyribonucleotides)

Question 13

Mycophenolic acid

Answer 13

Inhibit GMP synthesis from IMP (Purine nucleotide biosynthesis)

Question 14

5-fluorouracil

Answer 14

Inhibit thymidylate synthase (This enzyme converts dUMP to dTMP and requires tetrahydrofolate)

Question 15

Allopurinol

Answer 15

Inhibits xanthine oxidase (this enzyme converts hypoxanthine to xanthine and xanthine to uric acid)

Question 16

NSAID and aspirin

Answer 16

Inhibit cyclooxygenase and used as anti-inflammatory drug