| 释义 |
purine Phys. Chem.|ˈpjʊəriːn|
Also unsystematically purin.
[ad. Ger. purin, according to the inventor, Emil Fischer, ‘combined from the L. words pūrum pure, and ūricum uric (acid)’. By the Chemical Society spelt purine, as a base: see -ine5.]
A white crystalline basic substance C5H4N4, having a bicyclic structure consisting of fused imidazole and pyrimidine rings, which when oxidized forms uric acid (C5H4N4O3), and of which adenine, caffeine, xanthine, etc., are also derivatives, and known as the purines or members of the purine group; spec. adenine or guanine, two substituted purines found in nucleic acids, etc. Freq. attrib.
(The group C5N4H4 was so named by Fischer in 1884 as the source of derivatives then prepared and named by him, methyl-purin and trichlor-methylpurin; the substance itself was not isolated by him till 1898, 14 years after it had been named. See Berichte d. deutsch. chem. Gesellsch. XVII. 329 (1884), and XXXI. 2564 (1898).
1898Chem. News 16 Dec. 304/1 (heading) Molecular transformation in the group of purines. 1899Jrnl. Chem. Soc. LXXVI. i. 175 Purine,..is a readily soluble, well crystallised substance, which forms salts both with acids and with bases, and as regards its character in general falls naturally in the series uric acid, xanthine, hypoxanthine, purine. 1902Brit. Med. Jrnl. No. 2163, 14 June 1461 Under the term ‘purin’ all the substances that contain the nucleus C5N4 may be included. Ibid., The Estimation of Purin Bodies in food-stuffs... By the use of purin-free foods they ascertained the average amount of urinary purin in various individuals. 1921Spectator 21 May 658/1 Purin bodies, precursors of uric acid, and purin-free diets have likewise had their day, although as inculcating abstemiousness the latter played a useful part. 1952Sci. News XXIV. 43 The DNA isolated from different organs of the same animal species seems to be constant in composition with respect to the relative amounts of purine and pyrimidine bases but differs from samples obtained from other species. 1954New Biol. XVI. 15 Nucleic acids appear to consist of alternate purine and pyrimidine nucleotides arranged in a chain. In desoxyribose nucleic acid the purine is either adenine or guanine. 1970Nature 25 July 379/2 Naturally occurring cytokinins known so far have a purine nucleus as the essential moiety. 1973R. G. Krueger et al. Introd. Microbiol. x. 307/2 Pairings between purines would distort the helix because of the large size of the molecules. |