Pyrimidine Nucleotides & Anti-Folate Mechanisms

Question 1

what are pyrimidines synthesized from in de novo pathway?

Answer 1

glutamine
CO2
aspartate

Question 2

key regulatory site for de novo pyrimidine synthesis

Answer 2

Carbamoyl phosphate synthetase II (CPSII)

Question 3

how is CPSII regulated

Answer 3

-: UTP

Question 4

what enzyme/cofactor are necessary for pyrimidine salvage?

Answer 4

Enzyme: pyrimidine phosphoribosyltransferases
Cofactor: PRPP

Question 5

what happens to degraded pyrimidines?

Answer 5

pyrimidine ring is degraded to soluble molecules alpha-alanin and beta-aminoisobutyrate) that can enter CAC

Question 6

Ribonucleotide reductase - action and regulation

Answer 6

Action: ribonucleotides –> dexoxyribonucleotides
Regulation: transcriptional and allosteric mechanisms

Question 7

What is adenosine deaminase deficiency (ADA)?

Answer 7

conversion of adenosine to inosine is blocked; causes SCID b/c B and T cell dysfunction

Question 8

what does thymidylate synthase do?

Answer 8

dUMP –> dTMP; req THF

Question 9

what is produced by de novo pyrimidine synthesis pathway?

Answer 9

UMP, which is coverted –> UDP –> UTP –> CTP