Nucleotide synthesis

Question 1

PRPP synthetase catalyzes which reaction? What are inhibitors and activators?

Answer 1

Takes ribose-5-phosphate and phosphorylates it to ribose-5-phosphate PRPP
Inhibited by ADP and GDP

Question 2

What enzyme catalyzes PRPP to PRA?

What are its allosteric regulators?

Answer 2

Amidoribosyltransferase
Activated by PRPP
Inhibited by GMP, AMP

Question 3

What is the enzyme that catalyzes IMP to adenylosuccinate? Regulation?

Answer 3

Adenylosuccinate synthase

Inhibited by AMP (end product)

Question 4

What is the enzyme that catalyzes IMP to Xanthosine-5’-monophosphate? Regulation?

Answer 4

IMP dehydrogenase

Inhibited by GMP

Question 5

Allopurinol is converted to what, which inhibits what enzyme?

Answer 5

Oxypurinol, inhibiting Xanthine oxidase

Question 6

What is the enzyme that converts UTP to CTP? Where does the amino group come from?

Answer 6

CTP synthase.

Q

Question 7

Carbamoyl Phosphate synthetase II is regulated how?

Answer 7

Inhibited by UTP

Activated by PRPP

Question 8

What enzyme takes nucleoside 2’-diphosphates nucleotides to 2’DEoxynucleotide 5’-phosphates?

Answer 8

Ribonucloetide reductase

Question 9

What chemical must be oxidized in the process of ribonucleotide reductase’s activity? How is it reduced back?

Answer 9

Thioredoxin

NADPH

Question 10

What is the pharmacological inhibitor of ribonucleotide reductase? What is the consequence of this drug?

Answer 10

Hydroxyurea.

Inhibited cell proliferation

Question 11

What reaction does Thymidylate synthase catalyze? What is oxidized in the process?

Answer 11

dUMP to dTMP

N5,N10 methyl THF to dihydrofolate