Nucleotide Metabolism

Question 1

What is the starting point of nucleotide synthesis?

Answer 1

The creation of PRPP (from ribose-5-P and ATP)

Question 2

Carbon and nitrogen are added from what to form inosine monophosphate (IMP)? (4 species)

Answer 2

tetrahydrofolate, carbon dioxide, glutamine and aspartate

Question 3

If ADP and GDP are phosphorylated, they are led to form what?

Answer 3

RNA

Question 4

Name the disease:
Deficiency in purine nucleoside phosphorylase (PNP)
Symptoms:
Low but not absent T-cells, chronic infections, failure to thrive (FTT), neurlologic symptoms.

Answer 4

CID

Question 5

Name the disease:
Deficiency in adenosine deaminase (ADA). ADA deficiency leads to accumulation of 2-deoxyadenosine in the blood. This is toxic to lymphocytes.

Symptoms:
Low Lymphocytes
Costrochondral junction dysplasia (skeletal abnormalities)

Treatment:
Bone marrow transplant, +/- chemotherapy

Answer 5

SCID

Question 6

Name the disease:
Rare X linked syndrome, inherited deficiency in hypoxanthine-guanine phosphoribosyltransferase
Symptoms:
Characterized by self injury, often biting of the fingers and lips.
Elevated uric acid in urine, mental retardation, dystonia, recurrent vomiting

Answer 6

Lesch – Nyhan Disease (LND)

Question 7

How is gout and GMP and AMP connected?

Answer 7

GMP and AMP are degraded to xanthine, which is oxidized to uric acid by xanthine oxidase. When uric acid crystals build up, gout follows.

Question 8

What enzyme converts Glutamine + CO2 and 2ATP to Carbomyl Phosphate?

Answer 8

Cytosolic carbamoyl phosphate synthase (CPS II) uses glutamine as an amine donor to form carbamoyl phosphate.