17 - NUCLEOTIDES

PRPP glutamyl amidotransferase

Rate-limiting enzyme of purine synthesis

Carbamoyl phosphate synthetase II

Rate-limiting enzyme of pyrimidine synthesis

Glutamine, Aspartate

Carbon Dioxide

Donors of atoms that make up the pyrimidine ring

Glutamine, Aspartate,

Carbon Dioxide, Glycine

N10-formyltetrahydrofolate

Donors of atoms that make up the purine ring

Ribonucleotide reductase

Multi-subunit enzyme that reduces nucleoside diphosphates to their deoxy forms

N5, N10-methylene tetrahydrofolate

Co-factor of thymidylate synthase required to convert dUMP to thymine

5-phosphoribosyl-1-pyrophosphate (PRPP)

Donor of ribose 5-phosphate of nucleotides

Uric acid

Product of degradation of purine metabolism

β-alanine

β-aminoisobutyrate

Water-soluble, less likely to accumulate

Products of degradation of pyrimidine metabolism

Orotic aciduria

Disease associated with accumulation of pyrimidines

5-fluorouracil (5FU)

Chemotherapy drug that inhibits thymidylate synthase

Mycophenolate mofetil

Reversible inhibitor of IMP dehydrogenase, depriving lymphocytes of nucleic acids

Methotrexate

Inhibits dihydrofolate reductase

Sulfonamides

Structural analog of PABA that inhibits dihydropteroate synthase

Trimethoprim

Structural analog of folate that inhibits bacterial dihydrofolate reductase

Febuxostat

Allopurinol is a purine analog inhibitor of xanthine oxidase

Non-purine inhibitor of xanthine oxidase used in the treatment of hyperuricemia

Brain, RBCs, PMNs

Organs/cells dependent on exogenous purines

APRT: Adenosine phosphoribosyltransferase

HGPRT:

Hypoxanthine-Guanine phosphoribosyltransferase

Irreversible enzymes in the purine salvage pathway

HGPRT

Enzyme deficient in Lesch-Nyhan Syndrome, leading to self-mutilation & mental retardation

Severe Combined Immunodeficiency

Disease caused by deficiency of adenosine deaminase, presenting with absent lymphocyte production and overwhelming infection