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Uric acid displays lactam–lactim tautomerism. [4] Uric acid crystallizes in the lactam form, [5] with computational chemistry also indicating that tautomer to be the most stable. [6] Uric acid is a diprotic acid with pK a1 = 5.4 and pK a2 = 10.3. [7] At physiological pH, urate predominates in solution. [medical citation needed]
An evolutionary loss of urate oxidase (uricase), which breaks down uric acid, in humans and higher primates has made this condition common. [5] The triggers for precipitation of uric acid are not well understood. While it may crystallize at normal levels, it is more likely to do so as levels increase.
Rasburicase, sold under the brand name Elitek in the US and Fasturtec in the EU, is a medication that helps to clear uric acid from the blood. It is a recombinant version of urate oxidase, an enzyme that metabolizes uric acid to allantoin. Urate oxidase is known to be present in many mammals but does not naturally occur in humans. [3]
Unless high blood levels of uric acid are determined in a clinical laboratory, hyperuricemia may not cause noticeable symptoms in most people. [4] Development of gout – which is a painful, short-term disorder – is the most common consequence of hyperuricemia, which causes deposition of uric acid crystals usually in joints of the extremities, but may also induce formation of kidney stones ...
Because xanthine oxidase is a metabolic pathway for uric acid formation, the xanthine oxidase inhibitor allopurinol is used in the treatment of gout. Since xanthine oxidase is involved in the metabolism of 6-mercaptopurine, caution should be taken before administering allopurinol and 6-mercaptopurine, or its prodrug azathioprine, in conjunction.
Uricosurics are often used in the treatment of gout, a disease in which uric acid crystals form deposits in the joints. By decreasing plasma uric acid levels, help dissolve these crystals, while limiting the formation of new ones. However, the increased uric acid levels in urine can contribute to kidney stones.
Uric acid has the highest concentration of any blood antioxidant [69] and provides over half of the total antioxidant capacity of human serum. [75] Uric acid's antioxidant activities are also complex, given that it does not react with some oxidants, such as superoxide, but does act against peroxynitrite, [76] peroxides, and hypochlorous acid. [77]
The starting material for the reaction sequence was uric acid (8), which had been isolated from kidney stones by Carl Wilhelm Scheele in 1776. [12] Uric acid was reacted with PCl 5 to give 2,6,8-trichloropurine, which was converted with HI and PH 4 I to give 2,6-diiodopurine. The product was reduced to purine using zinc dust.