Purines, Pyrimidines and Nucleosides

PC was being used already 25 years ago for fractionation and quantitative analysis of these substances in nucleic acid hydrolysates [45, 46, 99, 105]. Randerath was the first to report the thin-layer chromatographic separation of nucleic acid constituents on silica gel G [59] and cellulose [60]. He found TLC on cellulose layers to be superior to PC [59, 61]. TLC on finely powdered cellulose layers yields smaller and more sharply defined spots than PC on the fibrous paper under comparable conditions [60] moreover, thin-layer chromatographic separation of nucleic acid derivatives requires only a fraction of the time needed in PC [60, 61]. 

Ion exchange-layers like DEAE- and ECTEOLA-cellulose [11, 35,59, 78] and PP-cellulose [55] also are suitable for separating bases and nucleosides. 

Procedures for preparing the various layers are given in Chapter B, p. 47. 

Water has been used as solvent on DEAE- and ECTEOLA-cellulose layers [11, 59] and also 0.005N hydrochloric acid [11] and isobutyric acid-conc. ammonium hydroxide-water (66 + 2 + 32) on the former [11]. Saturated ammonium sulphate solution-N sodium acetate-isopropanol (80 -f 18 + 2), a solvent which was developed for the PC [45] and TLC (cellulose) [60] of nucleotides, is particularly good for separating purine and pyrimidine bases on layers of DEAE-cellulose [11]. 

The photoprint procedure for photographic detection in UV light cannot of course be used with coated glass plates. 

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Voelter W, Records R, Bunnenberg E, Djerassi C (1968) Magnetic circular dichroism studies, vi. investigation of some purines, pyrimidines, and nucleosides. J Am Chem Soc 90 6163—6170... 

Purines, pyrimidines, and nucleosides, for example cytidine, condense with the vinylphosphonium salt (92) to yield (93), which on treatment with alkali eliminate triphenylphosphine. ... 

Determination of purines, pyrimidines, and nucleosides Although several LC procedures are available for separating mixtures of purines, pyrimidines, and nucleosides, it is generally more convenient to use specific columns for differentiating between these different classes of compounds. 

The luminescence properties of purines, pyrimidines, and nucleosides have been extensively investigated, mainly from a physicochemical standpoint. These compounds generally have low fluorescence quantum yields, between 0.01 and 0.06, according to the molecule, in glycol-water (1 1), pH 7, and at a low temperature (77 K). The fluorescence intensities of purines and pyrimidines are practically nil or very weak at room temperature, preventing the analytical use of this method. 

The s5mibols are intended to be applicable to both deoxyribonucleic and ribonucleic acids. In circumstances where confusion between DNA and RNA is likely the sequence may be prefixed with the lower-case letter d or r. Similarly, no distinction will be made in the symbols between base, nucleoside, and nucleotide. There are also corresponding three-letter symbols for the purines, pyrimidines, and nucleosides. The one-letter symbols were designed for pol3nner representation. The three-letter symbols should be used whenever chemical changes involving nucleosides or nucleotides are being discussed. 

Compound classes labeled by heterogeneous metal-catalyzed tritium exchange from water include amino acids, peptides and proteins, sugars, polycyclic aromatic hydrocarbons, purines, pyrimidines and nucleosides, alkyl-substituted aromatics, alicyclic compounds and steroids, A-heterocycles and anilines and some O- and 5-heterocycles. The method is firmly fixed in the repertoire of methods of the commercial custom labeling industry. 

Purines, pyrimidines and their nucleosides and nucleoside triphosphates are synthesized... 

Purines, pyrimidines, and the corresponding nucleosides have been separated in reversed phase systems. The five mqior nucleosides as well as inosine and xanthosine and the corresponding seven bases were separated by Hartwick and Brown (405). The selective determination of adenosine in the presence of other serum components has been reported (406). 

None of the extracts from unchlorinated model compounds were significantly different from the negative controls. Extracts of chlorinated purines-pyrimidines and chlorinated nucleosides-nucleotides were also found to be not significantly mutagenic. However, the extracts of all three chlorinated humic acids and the chlorinated amino acids were... 

Purines, pyrimidines and their nucleosides and nucleoside triphosphates are synthesized in the cytoplasm. At this stage the antifolate drugs (sulphonamides and dihydrofolate reductase inhibitors) act by interfering with the synthesis and recycling of the co-factor dihydrofolic acid (DHF). Thymidylic acid (2-deoxy-thymidine monophosphate, dTMP) is an essential nucleotide precursor of DNA synthesis. It is produced by the enzyme thymidylate synthetase by transfer of a methyl group from tetrahydrofolic acid (THF) to the uracil base on uridylic acid (2-deoxyuridine monophosphate, dUMP) (Fig. 12.5). THF is converted to DHF in this process and must be reverted to THF by the enzyme dihydrofolate reductase (DHFR) before... 

Two Nitrogen Atoms (it is self-sub divided into 1,2-Heterocycles, 1,3-Heterocycles Monocyclic Pyrimidines and Hydropyrimidines Except Pyrimidine Nucleoside Bases and Nucleosides, Annulated Pyrimidines Except Purines, Pteridines, and Flavins, Pyrimidine Nucleoside Bases and Purines, Nucleotides and Nucleosides, Nucleic Acids, Pyrazines, and Hydropyrazines). 

R. Carrington, G. Shaw, and W. Wilson, Purines, pyrimidines and imidazoles. XXIII. The use of P-D-ribosyl azide 5-phosphate in a new direct synthesis of nucleosides, J. Chem. Soc., 1965, 6864-6870. 

Jardetzky CD, Jardetzky O (1960) Investigation of the structure of purines, pyrimidines, ribose nucleosides and nucleotides by proton magnetic resonance.il. J Am Chem Soc... 

T. J. Kistenmacher and L. G. Marzilli, Chelate Metal Complexes of Purines Pyrimidines and Their Nucleosides Metal-Ligand and Ligand-Ligand Interactions. Jerusalem Symp. Quantum Chem. Biochem. 9(1), 7-40 (1977). 

Spectrometric methods are extremely useful for structural investigation and identification of purines, pyrimidines, nucleosides, and nucleotides. They allow the provisional identification of these compounds, made on the basis of chromatographic and electrophoretic behavior, to be confirmed. The application of MS, UV absorption spectrophotometry, and phosphorescence spectrometry to the identification and determination of purines, pyrimidines, and their derivatives is reviewed in the following sections. 

Nucleoside antibiotics purine or pyrimidine nucleosides with antibiotic activity. They act as antimetabolites of natural substrates, and inhibit the growth of microoiganisms by blocking the metabolism of purines, pyrimidines and proteins Some N.a. (e.g. showdomycin) contain an analog base, others (e.g. gougerotin) contain an analog sugar, or both moieties may be modified (e.g. puromycin) (see Table). 

The chemistry and metabolism of purines, pyrimidines, and their nucleosides and nucleotides constitute one of the oldest subjects of biochemistry, beginning as it does with the identification of uric acid in 1776. It is ironic that it has taken longer to work out the pathways of the synthesis, interconversion, and catabolism of these compounds than those of many other metabolites. 

Nutrition experiments showed that dietary nucleic acids or purines diminish allopurinol induced orotic aciduria (Zollner and Grobner 1971, Zollner and Grobner 1977). Using lymphoblasts cultures we showed that this might be due to an inhibition of pyrimidine synthesis by purines (Banholzer et al. 1980, Banholzer et al. 1981). In this study the influence of purine bases and nucleosides as well as of oxipurinol on pyrimidine biosynthesis was investigated usii rat hepatocytes in suspension. 

Purines, pyrimidines and their nucleosides and nucleotides are available commercially (Firms 26, 31, 80, 86, 98, 124, 130). Enzymes for degradation of nucleic acids are also obtainable (Firms 26, 154). 

Table 193. hRf-values of some purines, pyrimidines and their nucleosides from paper-and thin layer-chromatographic separations using water as developing solvent [59]... 

It is well established that aza analogs of purines, pyrimidines and their nucleosides possess significant but varying potency as antineoplastic agents [1-7]. Thus, for example, 6-azacytidine is an inhibitor for orotidylic acid decarboxylase [3] and 6-azauracil inhibits the development of animal tumors [4] and human acute leukemia [5] similarly, 8-azaguanine is a highly effective anti-neoplastic agent [6] and also inhibits animal tumors [7]. 

Boron-containing analogs of the biochemical precursors of nucleic acids, including purines, pyrimidines, thymines, nucleosides, and nucleotides, have been synthesized and several were evaluated in cellular and animal studies. Figure 10.8 shows several representative molecules of this class (35-42) containing carborane cages linked via various spacers to either the base or the carbohydrate... 

Purine and pyrimidine bases Nucleosides Nucleotides Nucleic acids... 

The most important derivatives of pyrimidines and purines are nucleosides Nucleosides are N glycosides m which a pyrimidine or purine nitrogen is bonded to the anomeric carbon of a carbohydrate The nucleosides listed m Table 28 2 are the mam building blocks of nucleic acids In RNA the carbohydrate component is d ribofuranose m DNA It IS 2 deoxy d ribofuranose... 

Table 28 2 doesn t include all of the nucleoside components of nucleic acids The presence of methyl groups on pyrimidine and purine rings is a common and often important variation on the general theme... 

Section 28 2 Nucleosides are carbohydrate derivatives of pyrimidine and purine bases The most important nucleosides are derived from d ribose and 2 deoxy D ribose... 

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