Principles of Biochemistry Volume 2 - A. Lehninger 1985

Bioenergetics and Metabolism
Biosynthesis of Amino Acids and Nucleotides
Excessive production of uric acid causes gout

Long mistakenly dismissed as a "disease of gourmets," Gout is caused by elevated levels of uric acid in Blood serum and Tissues. It is a joint disorder that predominantly affects men. The attacks of gouty Arthritis—characterized by severe pain, redness, and Swelling around the joints—are triggered by extensive deposits of urates (sodium urate crystals). The Kidneys are also affected because excess urates accumulate in the renal tubules. The exact cause of gout remains unknown; it is believed to stem from a hereditary partial deficiency of one of the Enzymes involved in purine METABOLISM.

Effective Treatment of gout is achieved by combining an appropriate diet with pharmacological therapy. Foods high in NUCLEOTIDES and Nucleic Acids, such as Liver, as well as coffee and tea, which contain the Purines caffeine and theobromine, are excluded from the diet. The Use of allopurinol yields excellent therapeutic results; this drug acts as an inhibitor of xanthine oxidase, the enzyme responsible for converting purines into uric acid (Fig. 22-25).

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Fig. 22-25. Allopurinol is an inhibitor of xanthine oxidase. A minor structural modification (highlighted against a red Background) in hypoxanthine (the enzyme's substrate) yields a potent enzyme inhibitor with therapeutic properties. Allopurinol, a highly effective medication, was specifically designed as a competitive inhibitor of xanthine oxidase.