Purine

One of the two classes of bases in DNA and RNA. The purine bases are guanine (G) and adenine (A). Uric acid, the offending substance in gout, is a purine end-product.

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The parent substance of adenine, guanine, and other naturally occurring p. “bases”; not known to exist as such in mammals.

- p.-nucleoside phosphorylase a ribosyltransferase that reversibly catalyzes the phosphorolysis of a p. nucleoside with orthophosphate to produce a p. and α-d-ribose 1-phosphate; an inherited deficiency of this enzyme leads to cellular immunodeficiency.

- p. ribonucleoside SYN: nebularine.

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pu·rine 'pyu̇(ə)r-.ēn n

1) a crystalline base C₅H₄N₄ that is the parent of compounds of the uric-acid group

2) a derivative of purine esp a base (as adenine or guanine) that is a constituent of DNA or RNA

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n.

a nitrogen-containing compound with a two-ring molecular structure. Examples of purines are adenine and guanine, which form the nucleotide of nucleic acids, and uric acid, which is the end-product of purine metabolism.

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pu·rine (puґrēn) [L. purum pure + urine] a heterocyclic compound, C₅H₄N₄, which is not found free in nature, but is variously substituted to produce a group of compounds known as purines or purine bases (see illustration under base), of which uric acid is a metabolic end product. The purine bases include adenine and guanine, which are constituents of nucleic acids, and hypoxanthine and xanthine.