Lecture 14 - Purine Synthesis (de novo biosynthesis)

Question 1

Step 1

Answer 1

Ribose 5-P -> phosphoribosyl pyrophosphate (PRPP)

Question 2

Enzyme of step 1

Answer 2

PRPP synthetase

Question 3

Cofactor of step 1

Answer 3

ATP -> AMP

Question 4

Step 2

Answer 4

Phosphoribosyl pyrophosphate -> phosphoribosyl amine

Question 5

Enzyme of step 2

Answer 5

Amido phosphoribosyl transferase

Question 6

Cofactor of step 2

Answer 6

• Glutamine -> glutamate

- PPi out

Question 7

Step 4a (adenine)

Answer 7

Inosine monophosphate -> adenylsuccinate

Question 8

Enzyme of step 4a (adenine)

Answer 8

Adenylosuccinate synthetase

Question 9

Cofactor of step 4a (adenine)

Answer 9

• Aspartate in

- GTP -> GDP + Pi

Question 10

Step 5a (adenine)

Answer 10

Adenylsuccinate -> adenosine-5’-monophosphate

Question 11

Enzyme of step 5a (adenine)

Answer 11

Adenylosuccinate lyase

Question 12

Cofactor of step 5a (adenine)

Answer 12

Fumarate out

Question 13

Step 4b (guanine)

Answer 13

Inosine monophosphate -> xanthylic acid

Question 14

Enzyme of step 4b (guanine)

Answer 14

Inosine monophosphate dehydrogenase

Question 15

Cofactor of step 4b (guanine)

Answer 15

NAD+ + H2O -> NADH + H+

Question 16

Step 5b (guanine)

Answer 16

Xanthylic acid -> guanosine-5’-monophosphate

Question 17

Enzyme of step 5b (guanine)

Answer 17

GMP synthetase

Question 18

Cofactor of step 5b (guanine)

Answer 18

• Glutamine -> glutamate

- ATP -> AMP + PPi

Question 19

What happens to the fumarate that is produced from adenine synthesis?

Answer 19

Converted back to aspartate, which is consumed in adenine synthesis

Question 20

Purines are made on the sugar base using _ ATP

Answer 20

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