r`ĭk), white, odorless, tasteless crystalline substance formed as a result of purine purine, type of organic base found in the nucleotides and nucleic acids of plant and animal tissue. The German chemist Emil Fischer did much of the basic work on purines and introduced the term into the chemical literature in the early 20th cent...... Click the link for more information. degradation in man, other primates, dalmatians, birds, snakes, and lizards. The last three groups of animals also channel all amino acid amino acid (əmē`nō)
..... Click the link for more information. degradation into the formation of glycine glycine (glī`sēn), organic compound, one of the 20 amino acids commonly found in animal proteins.
..... Click the link for more information. , aspartic acid aspartic acid (əspär`tĭk), organic compound, one of the 20 amino acids commonly found in animal proteins.
..... Click the link for more information. , and glutamine glutamine (gl
..... Click the link for more information. , which combine to form purines and finally uric acid; these so-called uricotelic organisms thus excrete uric acid as the major end-product of the metabolism of all nitrogen-containing compounds. Uric acid is a very weak organic acid that is barely soluble in water and insoluble in alcohol and ether. The urates are its salts. Uric acid is present in human urine only in extremely small amounts but constitutes a large part of the body waste matter of birds (see guano guano (gwä`nō), dried excrement of sea birds and bats found principally on the coastal islands of Peru, Africa, Chile, and the West
..... Click the link for more information. ) and of reptiles. It collects sometimes in the human kidneys or bladder in calculi, or stones, and is responsible, when present in tissues or deposited upon bones in the form of urates, for gouty conditions (see gout gout, condition that manifests itself as recurrent attacks of acute arthritis, which may become chronic and deforming. It results from deposits of uric acid crystals in connective tissue or joints.
..... Click the link for more information. ). It occurs also in normal human blood. The pure acid is obtained from guano and other similar substances. Upon decomposition urea is obtained. A common test for the presence of the acid in urine depends upon the formation of murexide (an ammonium salt), which is an intense reddish purple. Nitric acid is added to the urine, which is then evaporated. If uric acid is present, murexide is formed when ammonia is added to the residue.
uric acid
Heterocyclic compound of the purine type, the end product of metabolism of the purines in nucleic acids in many animals, including humans. It is excreted by reptiles and birds as the chief nitrogenous end product of protein breakdown. Small quantities are normally found in human blood; in gout, levels are abnormally high. Uric acid is used industrially in organic synthesis.
uric acid
uric acid [′yu̇r·ik ′as·əd]
Uric acid
The main excretory end product of protein metabolism in certain species of birds and reptiles. In mammals, uric acid is derived from purines; in higher primates, including humans, it is excreted as such and is not oxidized to allantoin, the main excretory purine metabolism product of most species. In humans, uric acid levels are increased following excessive intake of dietary purines, primary synthesis in certain diseases (gout, Lesch-Nyhan syndrome), endogenous nucleic acid metabolism (leukemia, an abnormal number of erythrocytes in blood, chemotherapy-induced tumor lysis), and restricted renal excretion (renal diseases, ketoacidosis, lacticidosis, diuretics). Uric acid levels are lowered by the use of drugs causing increased uric acid excretion, and by renal tubular defects. See Liver, Nucleic acid, Protein metabolism, Purine
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