| A | B |
|---|
| purine | adenine and guanine |
| purine nucleotide cycle | generates ammonia and fumarate in muscle |
| pyrimidines | catabolized to ammonia, bicarbonate, and either acetyl CoA or succinyl CoA |
| CTP | formed by the amination of UTP |
| IMP | can be converted to AMP or GMP |
| de novo | a synthesis of purine nucleotides that leads to IMP |
| deoxyribonucleotides | synthesized by the reduction of ribonucleotides at C-2 catalyzed by ribonucleotide reductase |
| nitrogen | excreted as uric acid from amino acids and purine nucleotides |
| AMP deaminase | an enzyme of purine catabolism that catalyzes the deamination of AMP to IMP |
| phosphorolysis | guanosine produces guanine or inosine produces hypoxanthine |
| gout | a disease caused by the overproduction or inadequate excretion of uric acid |
| allopurinol | given to treat gout |
| xanthine dehydrogenase | catalyzes the oxidation of allopurinol |
| pyrimidine | thymine, cytosine, and uracil |
| thymidylate synthase | converts dUMP to dTMP |
| thymidylate | required for DNA synthesis |
| CTP synthetase | catalyzes the ATP-dependent transfer of the amide nitrogen from glutamine to C-4 of UTP, forming CTP |
| ATP and GTP | when these increase, the rates of pyrimidine nucleotide synthesis also increases |
| carbamoyl phosphate synthetase | allosterically inhibited by UMP |
| adenylosuccinate synthetase | inhibited in vitro by AMP |
