| purine ribonucleoside | A toxic nucleoside isolated from the mushroom Agaricus nebularis and from Streptomyces sp. Synonym: 9-beta-ribofuranosylpurine, purine ribonucleoside, ribosylpurine. (05 Mar 2000) |
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| ribonucleoside | <biochemistry> A nucleoside in which purine or pyrimidine base is linked to a ribose molecule. (09 Oct 1997) |
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| ribonucleoside diphosphate reductase | <enzyme> An enzyme of the oxidoreductase class that catalyses the formation of 2'-deoxyribonucleotides from the corresponding ribonucleotides using NADPH as the ultimate electron donor. The deoxyribonucleoside diphosphates are used in DNA synthesis. Chemical name: 2'-Deoxyribonucleoside-diphosphate:oxidised-thioredoxin 2'-oxidoreductase Registry number: EC 1.17.4.1 (12 Dec 1998) |
| ribonucleoside-triphosphate reductase | <enzyme> Requires a cobamide coenzyme and ATP Registry number: EC 1.17.4.2 Synonym: rtp reductase (26 Jun 1999) |
| cytosine ribonucleoside | <biochemistry> Nucleoside consisting of D ribose and the pyrimidine base cytosine. (18 Nov 1997) |
| xanthine ribonucleoside | 9-beta-d-ribosylxanthine;the deamination product of guanosine (O replacing -NH2). Synonym: xanthine ribonucleoside. Abbreviation: Xao (05 Mar 2000) |
| purine | <biochemistry, molecular biology> A heterocyclic compound with a fused pyrimidine/imidazole ring. Planar and aromatic in character. The parent compound for the purine bases of nucleic acids. (18 Nov 1997) |
| purine 5'-nucleotidase | <enzyme> Associated with some immunologic deficiency diseases Registry number: EC 3.1.3.- (26 Jun 1999) |
| purine base | A purine. (05 Mar 2000) |
| purine-free diet | A diet containing a minimal quantity of purine bases (meats); liver, kidney, and sweetbread especially are excluded and replaced by dairy products, fruits, and cereals; alcoholic beverages also are excluded. Synonym: purine-free diet. (05 Mar 2000) |
| purine imidazole-ring cyclase | <enzyme> Recyclises ring-opened purine formamidopyrimidines in irradiated DNA, restoring the c-8 to n-9 band, does not require ATP Registry number: EC 6.3.3.- Synonym: purir cyclase (26 Jun 1999) |
| purine-nucleoside phosphorylase | <enzyme> An enzyme that catalyses the reaction between a purine nucleoside and orthophosphate to form a free purine plus ribose-5-phosphate. Chemical name: Purine-nucleoside:orthophosphate ribosyltransferase Registry number: EC 2.4.2.1 (12 Dec 1998) |
| purine permease | <chemical> Enzyme in transport system of purines in yeast pichia guillermondii Chemical name: permease, purine (26 Jun 1999) |
| purine phosphoribosyltransferase | <enzyme> Specific purine phosphoribosyltransferases are EC 2.4.2.7 and 2.4.2.8. Registry number: EC 2.4.2.- (26 Jun 1999) |
| purine-restricted diet | See: gout diet. (05 Mar 2000) |
| low purine diet | A diet low in precursors of purines (such as tissues rich in cells with abundant nuclei, as in liver, glandular meats, etc.) to minimise formation of uric acid. Useful in treatment of patients with gout or urate-containing renal calculi. (05 Mar 2000) |