Purine metabolism is the process by which purines are broken down to uric acid. Purines are found in many foods, including meat, poultry, fish, and legumes. Uric acid is the end product of purine metabolism and is excreted in urine.
The first step in purine metabolism is the breakdown of purines to form ammonia and carbon dioxide. This reaction is catalyzed by the enzyme purine nucleosidase. Ammonia is then converted to urea by the enzyme urease. Urea is excreted in urine. The second step in purine metabolism is the conversion of ammonia to uric acid by the enzyme xanthine oxidase. Uric acid is also excreted in urine.
In humans,purine metabolism occurs primarily in the liver and kidney. The liver breaks down purines to form ammonia and carbon dioxide, which are then transported to the kidney for further processing. The kidney converts ammonia to urea and uric acid, which are both excreted in urine.