نتایج جستجو برای: purine de rivatives
تعداد نتایج: 1541505 فیلتر نتایج به سال:
Evidence has been presented for a metabolic multienzyme complex, the purinosome, that participates in de novo purine biosynthesis to form clusters in the cytoplasm of living cells under purine-depleted conditions. Here we identified, using fluorescent live cell imaging, that a microtubule network appears to physically control the spatial distribution of purinosomes in the cytoplasm. Application...
1. The effect of an 18, 30 or 40 h fast on the rate of purine biosynthesis de novo as measured by the incorporation of [14C]formate into formylglycinamide ribonucleotide during azaserine block has been examined in the rat spleen. 2. There is a reproducible fall in the rate of purine biosynthesis de novo during fasting. Values at 40 h were approximately one-third of the values in the colony-fed ...
It has been hypothesized that components of enzymatic pathways might organize into intracellular assemblies to improve their catalytic efficiency or lead to coordinate regulation. Accordingly, de novo purine biosynthesis enzymes may form a purinosome in the absence of purines, and a punctate intracellular body has been identified as the purinosome. We investigated the mechanism by which human d...
The cultured rat embryo undergoing organogenesis (9.5-11.5 days of gestation) together with its associated yolk sac synthesize purine nucleotides via the de novo synthetic pathway. Although both the embryo and its yolk sac contain significant levels of the purine base salvage enzymes adenine phosphoribosyltransferase and hypoxanthine phosphoribosyltransferase, the culture medium that consists l...
Purines are molecules essential for many cell processes, including RNA and DNA synthesis, regulation of enzyme activity, protein synthesis and function, energy metabolism and transfer, essential coenzyme function, and cell signaling. Purines are produced via the de novo purine biosynthesis pathway. Mutations in purine biosynthetic genes, for example phosphoribosylaminoimidazole carboxylase/phos...
Enzymes in the de novo purine biosynthesis pathway are recruited to form a dynamic metabolic complex referred to as the purinosome. Previous studies have demonstrated that purinosome assembly responds to purine levels in culture medium. Purine-depleted medium or 2-dimethylamino4,5,6,7-tetrabromo-1H-benzimidazole (DMAT) treatment stimulates the purinosome assembly in HeLa cells. Here, several me...
Exogenous purines are known to suppress purine synthesis de novo in bacteria (2-4), HeLa and L cells (5), and ascites cells (6) growing in culture. High levels of purines, especially adenine, inhibit accumulation of late purine precursors in the media of bacteria with blocks in the pathway of purine synthesis (2, 3), or of formylglycinamide ribonucleotide in Ehrlich ascites cells grown in the p...
Purine nucleotides are essential components to sustain plant growth and development. In plants they are either synthesized "de novo" during the process of purine biosynthesis or are recycled from purine bases and purine nucleosides throughout the salvage pathway. Comparison between animals, microorganisms and Arabidopsis, the first plant species with a completely sequenced genome, shows that pl...
Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acid synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenosine and guanine nucleotides. We describe a distinct early-onset neurodegenerative condition resulting from mutations in the adenosine monophosphate ...
The purine metabolism of several genera of parasitic protozoa, is of interest partly due to their sensitivity to purine analogues, and to differences in the enzymes of purine metabolism compared to mammalian systems [l-6]. Trichomonas vaginalis, the causative agent of trichomonal vaginitis, a mild, but very common, sexually-transmitted disease, has not been studied in this respect; there is a g...
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