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Disorders of Purine and Pyrimidine Metabolism

  1. Functions of Nucleotides
    • - Nucleotides serve as carriers of activated intermediates in the synthesis of
    •             Carbohydrataes - e.g. UDP-glucose
    •             Lipids - e.g. CDP-choline
    •             Conjugated proteins – e.g. Helicase enzymes
    • - Nucleotides also act as “second messengers”
    •          e.g. cyclic AMP
    • - Nucleotides hold onto and transmit directed energy
    •           (i.e. ATP and GTP as “Energy Currency”)
  2. T and U differ only in that Thimine................
    Thimine has an additional (1 carbon) methyl group
  3. How purine is degraded?
    • Phosphodiesterase enzymes cleave oligosaccharides into mononucleotides
    • Nucleotidase enzymes then remove the phosphate, giving nucleosides
  4. - ............. is the “end product” of purine breakdown
    - Formed primarily in...................
    • Uric acid is the “end product” of purine breakdown
    • Formed primarily in intestinal mucosal cells
  5. - Uric acid is formed from..................
    Hypoxanthine 
  6. What happens when Uric Acid crystallizes?
    • - It deposits and forms Gout
    • - If it deposits in the Kidney form Kidney Stones
  7. The vast majority of gout happens because of inadequate excretion 
    • 1- Defects in kidney function
    • 2- Lactate acidosis (which could lower the pH of urine and cause more urate to become insoluble)
    • 3- Environmental factors, or taking certain drugs
  8. How you treat Gout?
    1- Lessen the amount of inflammation (i.e use steroids, NSAIDS)

    • 2- Get rid of the excess uric acid
    • a- Use Uricosuric Agents to increase renal excretion.           -------Probenecid
    • -------Sulfinpyrazone
    • B- Use Allopuranol (a structural analog of hypoxanthine) to inhibit synthesis of Uric Acid

    • 3- Make it more soluble 
    • ----Urate Oxidase – that converts Uric Acid into Allantoin
    • ---Allantoin is five to ten times more soluble than uric acid, so renal excretion is more effective
  9. The key regulated step in the pyrimidine synthesis is making of ----------------
    Carbamoyl phosphate
  10. There are 2 Carbamoyl Phosphate Synthesis
    (CPS) enzymes (I and II).
    CPS I contributes to synthesis.............
    CPS II contributes to synthesis..............
    • There are 2 Carbamoyl Phosphate Synthesis
    • (CPS) enzymes (I and II).
    • CPS I contributes to synthesis of urea;
    • CPS II contributes to synthesis of pyrimidines
Author
mgeorgi1
ID
174616
Card Set
Disorders of Purine and Pyrimidine Metabolism
Description
Biochemistry
Updated

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