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Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C 5 H 4 N 4 O 3. It forms ions and salts known as urates and acid urates, such as ammonium acid urate. Uric acid is a product of the metabolic breakdown of purine nucleotides, and it is a normal component of urine. [1]
Uric acid has the highest concentration of any blood antioxidant [58] and provides over half of the total antioxidant capacity of human serum. [64] 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, [65] peroxides, and hypochlorous acid. [66]
Uricotelism is the excretion of excess nitrogen in the form of uric acid. [4] Uricotelic animals include insects , birds and most reptiles . Though requiring more metabolic energy to make than urea, uric acid's low toxicity and low solubility in water allow it to be concentrated into a small volume of pasty white suspension in feces, compared ...
Urate oxidase is the first enzyme in a pathway of three enzymes to convert uric acid to S-(+)-allantoin. After uric acid is converted to 5-hydroxyisourate by urate oxidase, 5-hydroxyisourate (HIU) is converted to 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) by HIU hydrolase, and then to S-(+)-allantoin by 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase (OHCU decarboxylase).
Mutations in the gene lead to hyperuricemia.At least 67 disease-causing mutations in this gene have been discovered: [5] Some men have partial (up to 20% less activity of the enzyme) HGPRT deficiency that causes high levels of uric acid in the blood, which leads to the development of gouty arthritis and the formation of uric acid stones in the urinary tract.
However the last enzyme is absent in humans, explaining the disease known as gout, caused by the accumulation of uric acid. Certain enzymes within the peroxisome, by using molecular oxygen, remove hydrogen atoms from specific organic substrates (labeled as R), in an oxidative reaction, producing hydrogen peroxide (H 2 O 2 , itself toxic):
U.S. President-elect Donald Trump refused on Tuesday to rule out using military or economic action to pursue acquisition of the Panama Canal and Greenland, part of a broader expansionist agenda he ...
The other purine nucleoside, guanosine, is cleaved to form guanine. Guanine is then deaminated via guanine deaminase to form xanthine which is then converted to uric acid. Oxygen is the final electron acceptor in the degradation of both purines. Uric acid is then excreted from the body in different forms depending on the animal. [5]