 From normal turnover of cellular nucleic acids  Obtained from the diet  Reutilization of adenine, hypoxanthine, and guanine  Two enzymes: 1. Adenine phosphoribosyltransferase 2. Hypoxanthine-guanine phosphoribosyltransferase

Hypoxanthine Xanthine Xanthine dehydrogenase Allopurinol

Build up of hypoxanthine and guanine Degradation of hypoxanthine and guanine results in increased uric acid Absence of Hypoxanthine-guanine phosphoribosyltransferase. Excess uric acid in urine often results in orange crystals in the diaper of affected children Severe mental retardation Self-mutilation Involuntary movements Gout Lesch-Nyhan Syndrome

Very Important!

Guanine-Cytosine Adenine-Thymine DNA Base Pairing

 %A = %T and %G = %C  In DNA, 1:1 ratio between purines and pyrimidines Organism%A%G%C%TA/TG/C%GC%AT φX Maize Octopus Chicken Rat Human Grasshopper Sea Urchin Wheat Yeast E. Coli

 Purines: Uric acid  Reutilization of adenine, hypoxanthine and guanine  End product: Urate (a.k.a.: Uric Acid )  Altered metabolism: Gout  Pyrimidines: Citric acid intermediates  Acetyl-CoA derived from Cytosine and Uracil degradation; Propionyl-CoA (Succinoyl-CoA) from Thymine degradation  Ammonia and CO 2  Ring undergoes complete degradation