A purine-requiring mutant (strain W-11) of Escherichia coli strain K-12, has been shown to synthesize 5-aminoimidazole riboside precursors (Love and Gots, 1955). This strain was thought to lack the enzymes responsible for the conversion of aminoimidazole ribotide to purines. On the basis of information on the biosynthesis of purines carried out with enzyme systems from pigeon liver (Buchanan et...

The effects of 9-butyl-6-thioguanine (9-BTG)1 on the utilization of preformed purines by the Ehrlich ascites tumor were studied in vivo.The results showed that 9-BTG inhibited the utilization of preformed purines for DNA synthesis under conditions in which UNA synthesis and the incorporation of glycine into proteins and nucleic acids were unaffected. Studies on the incorporation of glycine-2-C1...

The pattern of formate-Cl4 incorporation by Ehrlich ascites tumor cells has been found to be remarkably different in vitro from the pattern of incorporation in vivo (3-5). Thus, after incubation of cells with formate-Cl4 in vitro, the specific activity of the DNA thymine was 10 to 30 times higher than that of the DNA purines. In contrast, after incorporation of formateCl4 by these cells in viva...

BACKGROUND The aim of the study was to measure the content of methylated purines that appear as admixtures in uric acid stones. METHODS We analyzed urinary calculi from 48 residents of Western Pomerania who underwent surgery at the urology ward in Szczecin. Stone samples were dissolved in 0.1 mol/L NaOH. Extracts were diluted in 50 mmol/L KH(2)PO(4) and analyzed by reversed-phase HPLC with ul...

Nucleotide metabolism results in the synthesis of the four nucleotides that form DNA. These are further divided in two categories: purines and pyrimidines. Their construction and degradation takes place in a progression of single steps, while different enzymes and cofactors are involved in the process. Beside degradation, there is also a form of reprocessing purine and pyrimidine nucleotides, d...

Armitt & Woods (1970) and Lomax & Woods (1973) reported the isolation of a series of mutants of Saccharomyces cerevisiae that did not require purines for growth, but excreted substantial amounts of purines into the growth medium. Genetic studies have assigned these yeast strains to six unlinked genes (purl, pur2, pur3, pur4, pur.5, pzv6), of which one, pur6, had both recessive and dominant (PUR...

2,2'-Disubstitutedamino-4-4'-bis-pyrimidines (3a-m) have been prepared by linking 2,4-dichloro-6-methyl-5-nitropyrimidine (1) with several diamines and subsequent reaction with suitable amines. Some of these compounds (3c and 3j) which were reduced catalitically, on treatment with nitrous acid, urea in pyridine, and boiling thionyl chloride gave the corresponding bistriazolopyrimidin (6), ...

Recent data have provided evidence that microglia, the brain-resident macrophage-like cells, modulate neuronal activity in both physiological and pathophysiological conditions, and microglia are therefore now recognized as synaptic partners. Among different neuromodulators, purines, which are produced and released by microglia, have emerged as promising candidates to mediate interactions betwee...

The pathways of purine biosynthesis and degradation have been elucidated during the last 30 years; the regulation of the mechanisms involved is not yet fully understood, particularly with respect to quantitative aspects. Research into inborn errors of purine metabolism has provided valuable insights into purine synthesis and salvage pathways. Nutrition experiments using purine-free formula diet...

The 50 non-coding bases immediately internal to the telomeric repeats in the two 5' ends of macronuclear DNA molecules of a group of hypotrichous ciliates are anomalous in composition, consisting of 61% purines and 39% pyrimidines, A>T (ratio of 44:32), and G>C (ratio of 17:7). These ratio imbalances violate parity rule 2, according to which A should equal T and G should equal C within a DNA st...