According to PCI

1. CatabolismofPyrimidine
nucleotides
By : Ishika Choudhary
ARKA JAIN UNIVERSITY
Jamshedpur

2. Introduction :
• Nucleic acids (DNA , RNA) are formed by the polymerisation of
nucleotide subunits.
• Nucleotides are made up of a ribose sugar, a nitrogenous
base, and phosphate group(s) .
• Nucleotides are the structural units of nucleic acids, and also
perform various cellular functions.
• Nucleotides contain two types of nitrogenous base :
• purines(adenine and guanine)
• pyrimidines(cytosine, thymine and uracil)
• DNA contains thymine base , while the RNA contains uracil
base.

5. Catabolism of pyrimidine
nucleotides :
• Pyrimidine is catabolised into highly water
soluble compounds.
• This make it different from purine which on
catabolism gives uric acid (a sparingly soluble
products).

7. The end products of
pyrimidine metabolism are :
•CO2
•NH3
•Beta-alanine , and
•Beta-aminoisobutyrate .

8. Catabolism of pyrimidine

9. • Possibly , in humans beta-aminoisobutyrate is
transaminated into methylmalonate semi-
aldehyde , which is then converted into succinyl-
coA via methylmalonyl-coA .
• The beta-alanine can serve as precursor of
acetyl-coA .
• Thus , the malonyl-coA diverts to fatty acid
synthesis and succinyl-coA enters the citric acid
cycle .