hypoxanthine

6-Oxypurine; purin-6(1H)-one; a purine present in the muscles and other tissues, formed during purine catabolism by deamination of adenine; elevated in molybdenum-cofactor deficiency. SYN: 6-hydroxypurine.

- h. guanine phosphoribosyltransferase (HGPRT) SYN: h. phosphoribosyltransferase.

- h. oxidase SYN: xanthine oxidase.

- h. phosphoribosyltransferase an enzyme present in human tissue that converts h. and guanine to their respective 5′ nucleotides, with 5-phosphoribose 1-diphosphate as the ribose-phosphate donor; a partial deficiency of this enzyme can result in elevated purine biosynthesis resulting in gout; another level of deficiency is associated with Lesch-Nyhan syndrome. SYN: h. guanine phosphoribosyltransferase.

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hy·po·xan·thine .hī-pō-'zan-.thēn n a purine base C₅H₄N₄O found in plant and animal tissues that yields xanthine on oxidation and is an intermediate in uric acid synthesis

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hy·po·xan·thine (hi″po-zanґthēn) 6-oxypurine, a purine base formed as an intermediate in the degradation of purines and purine nucleosides to uric acid and in the salvage of free purines. It is found in some transfer RNA molecules and occurs complexed with ribose as the nucleoside inosine.