Catabolism of Purine Nucleotides

• Catabolism of Purine Nucleotides involves the breakdown of nucleotides into their constituent components, ultimately leading to the formation of uric acid.
• Catabolism of Purine Nucleotides process occurs mainly in the liver and involves several key enzymes.

Steps in Purine Catabolism

• Degradation of AMP and GMP:

  1. AMP Catabolism:

     • AMP is deaminated to inosine monophosphate (IMP) by the enzyme AMP deaminase.
     • IMP is hydrolyzed to inosine by the enzyme nucleosidase.
     • Inosine is further hydrolyzed to hypoxanthine by purine nucleoside phosphorylase (PNP).

  2. GMP Catabolism:

     • GMP is hydrolyzed to guanosine by nucleosidase.
     • Guanosine is converted to guanine by PNP.
     • Guanine is deaminated to xanthine by the enzyme guanine deaminase.

  3. Conversion to Uric Acid:

     • Hypoxanthine and xanthine are oxidized to uric acid by the enzyme xanthine oxidase.
     • Hypoxanthine is first converted to xanthine and then xanthine to uric acid.

Key Enzymes:

• AMP Deaminase
• Nucleotidases
• Purine Nucleoside Phosphorylase (PNP)
• Guanine Deaminase
• Xanthine Oxidase

Pathway Summary of Catabolism of Purine Nucleotides:

• AMP  →  IMP  →  Inosine  →  Hypoxanthine  →  Xanthine  →  Uric Acid
• GMP  →  Guanosine  →  Guanine  →  Xanthine  →  Uric Acid

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