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Sample records for regulates purine nucleotide

  1. Degradation of brown adipocyte purine nucleotides regulates uncoupling protein 1 activity

    Directory of Open Access Journals (Sweden)

    Tobias Fromme

    2018-02-01

    Full Text Available Objective: Non-shivering thermogenesis in mammalian brown adipose tissue depends on thermogenic uncoupling protein 1. Its activity is triggered by free fatty acids while purine nucleotides mediate inhibition. During activation, it is thought that free fatty acids overcome purine-mediated inhibition. We measured the cellular concentration and the release of purine nucleotide metabolites to uncover a possible role of purine nucleotide degradation in uncoupling protein 1 activation. Methods: With mass spectrometry, purine nucleotide metabolites were quantified in cellular homogenates and supernatants of cultured primary brown adipocytes. We also determined oxygen consumption in response to a β-adrenergic agonist. Results: Upon adrenergic activation, brown adipocytes decreased the intracellular concentration of inhibitory nucleotides (ATP, ADP, GTP and GDP and released the respective degradation products. At the same time, an increase in cellular calcium occurred. None of these phenomena occurred in white adipocytes or myotubes. The brown adipocyte expression of enzymes implicated in purine metabolic remodeling is altered upon cold exposure. Pharmacological and genetic interference of purine metabolism altered uncoupling protein 1 mediated uncoupled respiration. Conclusion: Adrenergic stimulation of brown adipocytes lowers the intracellular concentration of purine nucleotides, thereby contributing to uncoupling protein 1 activation. Keywords: Purine nucleotides, Uncoupling protein 1, Brown adipose tissue, Non-shivering thermogenesis, HILIC-MS/MS, Guanosine monophosphate reductase

  2. Involvement of the ribose operon repressor RbsR in regulation of purine nucleotide synthesis in Escherichia coli.

    Science.gov (United States)

    Shimada, Tomohiro; Kori, Ayako; Ishihama, Akira

    2013-07-01

    Escherichia coli is able to utilize d-ribose as its sole carbon source. The genes for the transport and initial-step metabolism of d-ribose form a single rbsDACBK operon. RbsABC forms the ABC-type high-affinity d-ribose transporter, while RbsD and RbsK are involved in the conversion of d-ribose into d-ribose 5-phosphate. In the absence of inducer d-ribose, the ribose operon is repressed by a LacI-type transcription factor RbsR, which is encoded by a gene located downstream of this ribose operon. At present, the rbs operon is believed to be the only target of regulation by RbsR. After Genomic SELEX screening, however, we have identified that RbsR binds not only to the rbs promoter but also to the promoters of a set of genes involved in purine nucleotide metabolism. Northern blotting analysis indicated that RbsR represses the purHD operon for de novo synthesis of purine nucleotide but activates the add and udk genes involved in the salvage pathway of purine nucleotide synthesis. Taken together, we propose that RbsR is a global regulator for switch control between the de novo synthesis of purine nucleotides and its salvage pathway. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  3. Antinociceptive effect of purine nucleotides.

    Science.gov (United States)

    Mello, C F; Begnini, J; De-La-Vega, D D; Lopes, F P; Schwartz, C C; Jimenez-Bernal, R E; Bellot, R G; Frussa-Filho, R

    1996-10-01

    The antinociceptive effect of purine nucleotides administered systematically (sc) was determined using the formalin and writhing tests in adult male albino mice. The mechanisms underlying nucleotide-induced antinociception were investigated by preinjecting the animals (sc) with specific antagonists for opioid (naloxone, 1 mg/kg), purinergic P1 (caffeine, 5, 10, of 30 mg/kg); theophylline, 10 mg/kg) or purinergic P2 receptors (suramin, 100 mg/kg; Coomassie blue, 30-300 mg/kg; quinidine, 10 mg/kg). Adenosine, adenosine monophosphate (AMP), diphosphate (ADP) and triphosphate (ATP) caused a reduction in the number of writhes and in the time of licking the formalin-injected paw. Naloxone had no effect on adenosine- or adenine nucleotide-induced antinociception. Caffeine (30 mg/kg) and theophylline (10 mg/kg) reversed the antinociceptive action of adenosine and adenine nucleotide derivatives in both tests. P2 antagonists did not reverse adenine nucleotide-induced antinociception. These results suggest that antinociceptive effect of adenine nucleotides is mediated by adenosine.

  4. The PurR regulon in Lactococcus lactis – transcriptional regulation of the purine nucleotide metabolism and translational machinery

    DEFF Research Database (Denmark)

    Jendresen, Christian Bille; Martinussen, Jan; Kilstrup, Mogens

    2012-01-01

    Purine nucleotides are either synthesized de novo from 5-phosphoribosyl-1-pyrophosphate (PRPP) or salvaged from the environment. In Lactococcus lactis, transcription of the de novo synthesis operons, purCSQLF and purDEK, has genetically been shown to be activated by the PurR protein when bound to......-related functions. Of special interest is the presence of PurBox motifs in rrn promoters, suggesting a novel connection between nucleotide availability and the translational machinery....

  5. The regulation of aortic endothelial cells by purines and pyrimidines involves co-existing P2y-purinoceptors and nucleotide receptors linked to phospholipase C.

    Science.gov (United States)

    Wilkinson, G F; Purkiss, J R; Boarder, M R

    1993-03-01

    1. We have examined the phospholipase C responses in bovine aortic endothelial cells to purines (ATP, ADP and analogues) and the pyrimidine, uridine triphosphate (UTP). 2. The cells responded to purines in a manner consistent with the presence of P2y purinoceptors; both 2-methylthioadenosine 5'-triphosphate (2MeSATP) and adenosine 5'-0-(2-thiodiphosphate) (ADP beta S) were potent agonists (EC50 0.41 microM and 0.85 microM respectively) while beta, gamma-methylene ATP at 300 microM was not. 3. The cells also responded to UTP. The maximal response to UTP was less than that for either 2MeSATP and ADP beta S while adenosine 5'-0-(3-thiotriphosphate) (ATP gamma S) gave the largest maximal response. 4. The concentration-effect curve to UTP was additive in the presence of either 2MeSATP or ADP beta S. However, the concentration-effect curves to ATP gamma S reached the same maximum in the presence or absence of UTP. 5. Suramin, at concentrations between 10 microM and 100 microM was a competitive antagonist for the response to ADP beta S and 2MeSATP but not the response to UTP. 6. The results show that there are two separate, co-existing, receptor populations: P2y-purinoceptors (responding to purines) and nucleotide receptors (responding to both purines and pyrimidines). We conclude that purines such as ATP/ADP may regulate aortic endothelial cells by interacting with two phospholipase C-linked receptors.

  6. The regulation of aortic endothelial cells by purines and pyrimidines involves co-existing P2y-purinoceptors and nucleotide receptors linked to phospholipase C.

    OpenAIRE

    Wilkinson, G. F.; Purkiss, J. R.; Boarder, M. R.

    1993-01-01

    1. We have examined the phospholipase C responses in bovine aortic endothelial cells to purines (ATP, ADP and analogues) and the pyrimidine, uridine triphosphate (UTP). 2. The cells responded to purines in a manner consistent with the presence of P2y purinoceptors; both 2-methylthioadenosine 5'-triphosphate (2MeSATP) and adenosine 5'-0-(2-thiodiphosphate) (ADP beta S) were potent agonists (EC50 0.41 microM and 0.85 microM respectively) while beta, gamma-methylene ATP at 300 microM was not. 3....

  7. Enhanced activity of the purine nucleotide cycle of the exercising muscle in patients with hyperthyroidism.

    Science.gov (United States)

    Fukui, H; Taniguchi , S; Ueta, Y; Yoshida, A; Ohtahara, A; Hisatome, I; Shigemasa, C

    2001-05-01

    Myopathy frequently develops in patients with hyperthyroidism, but its precise mechanism is not clearly understood. In this study we focused on the purine nucleotide cycle, which contributes to ATP balance in skeletal muscles. To investigate purine metabolism in muscles, we measured metabolites related to the purine nucleotide cycle using the semiischemic forearm test. We examined the following four groups: patients with untreated thyrotoxic Graves' disease (untreated group), patients with Graves' disease treated with methimazole (treated group), patients in remission (remission group), and healthy volunteers (control group). To trace the glycolytic process, we measured glycolytic metabolites (lactate and pyruvate) as well as purine metabolites (ammonia and hypoxanthine). In the untreated group, the levels of lactate, pyruvate, and ammonia released were remarkably higher than those in the control group. Hypoxanthine release also increased in the untreated group, but the difference among the patient groups was not statistically significant. The accelerated purine catabolism did not improve after 3 months of treatment with methimazole, but it was completely normalized in the remission group. This indicated that long-term maintenance of thyroid function was necessary for purine catabolism to recover. We presume that an unbalanced ATP supply or conversion of muscle fiber type may account for the acceleration of the purine nucleotide cycle under thyrotoxicosis. Such acceleration of the purine nucleotide cycle is thought to be in part a protective mechanism against a rapid collapse of the ATP energy balance in exercising muscles of patients with hyperthyroidism.

  8. Inhibitory effect of extracellular purine nucleotide and nucleoside concentrations on T cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Weiler, Monica [Department of Medicine III and Transfusion Medicine, University Hospital Grosshadern, Ludwig-Maximilians-University, Munich (Germany); Schmetzer, Helga [Helmholtz Center Munich (Germany); German Research Center for Environmental Health, Munich (Germany); Braeu, Marion; Buhmann, Raymund [Helmholtz Center Munich (Germany); German Research Center for Environmental Health, Munich (Germany); Department of Medicine III and Transfusion Medicine, University Hospital Grosshadern, Ludwig-Maximilians-University, Munich (Germany)

    2016-11-15

    The release of nucleic acids and derivatives after tissue-injury may affect cellular immune-response. We studied the impact of extracellular ribo-, desoxyribonucleotides and nucleosides on T-cell immunity. Peripheral-blood-mononuclear-cells (PBMCs) or isolated CD3{sup +}T-cells obtained from 6 healthy donors were stimulated via CD3/CD28 Dynabeads or dendritic cells (DCs) in the presence or absence of pyrimidine-, purine-nucleotides and -nucleosides (range 2–200 µM). Addition of deoxy-, guanosine-triphosphate (dGTP, GTP) and guanosine resulted concentration dependent in a complete, adenosine-triphosphate (ATP) in a partial inhibition of the induced T-cell-proliferation. Deoxyadenosine-triphosphate (dATP), adenosine and the pyrimidine-ribo- and -deoxyribonucleotides displayed no inhibitory capacity. Inhibitory effects of dGTP and GTP, but not of guanosine and ATP were culture-media-dependent and could be almost abrogated by use of the serum-free lymphocyte-culture-media X-Vivo15 instead of RPMI1640 with standard-supplementation. In contrast to RPMI1640, X-Vivo15 resulted in a significant down-regulation of the cell-surface-located ectonucleotidases CD39 (Ecto-Apyrase) and CD73 (Ecto-5′-Nucleotidase), critical for the extracellular nucleotides-hydrolysis to nucleosides, explaining the loss of inhibition mediated by dGTP and GTP, but not Guanosine. In line with previous findings ATP was found to exert immunosuppressive effects on T-cell-proliferation. Purine-nucleotides, dGTP and GTP displayed a higher inhibitory capacity, but seem to be strictly dependent on the microenvironmental conditions modulating the responsiveness of the respective T-lymphocytes. Further evaluation of experimental and respective clinical settings should anticipate these findings.

  9. Inhibitory effect of extracellular purine nucleotide and nucleoside concentrations on T cell proliferation

    International Nuclear Information System (INIS)

    Weiler, Monica; Schmetzer, Helga; Braeu, Marion; Buhmann, Raymund

    2016-01-01

    The release of nucleic acids and derivatives after tissue-injury may affect cellular immune-response. We studied the impact of extracellular ribo-, desoxyribonucleotides and nucleosides on T-cell immunity. Peripheral-blood-mononuclear-cells (PBMCs) or isolated CD3 + T-cells obtained from 6 healthy donors were stimulated via CD3/CD28 Dynabeads or dendritic cells (DCs) in the presence or absence of pyrimidine-, purine-nucleotides and -nucleosides (range 2–200 µM). Addition of deoxy-, guanosine-triphosphate (dGTP, GTP) and guanosine resulted concentration dependent in a complete, adenosine-triphosphate (ATP) in a partial inhibition of the induced T-cell-proliferation. Deoxyadenosine-triphosphate (dATP), adenosine and the pyrimidine-ribo- and -deoxyribonucleotides displayed no inhibitory capacity. Inhibitory effects of dGTP and GTP, but not of guanosine and ATP were culture-media-dependent and could be almost abrogated by use of the serum-free lymphocyte-culture-media X-Vivo15 instead of RPMI1640 with standard-supplementation. In contrast to RPMI1640, X-Vivo15 resulted in a significant down-regulation of the cell-surface-located ectonucleotidases CD39 (Ecto-Apyrase) and CD73 (Ecto-5′-Nucleotidase), critical for the extracellular nucleotides-hydrolysis to nucleosides, explaining the loss of inhibition mediated by dGTP and GTP, but not Guanosine. In line with previous findings ATP was found to exert immunosuppressive effects on T-cell-proliferation. Purine-nucleotides, dGTP and GTP displayed a higher inhibitory capacity, but seem to be strictly dependent on the microenvironmental conditions modulating the responsiveness of the respective T-lymphocytes. Further evaluation of experimental and respective clinical settings should anticipate these findings.

  10. The effect of exhaustive exercise on the concentration of purine nucleotides and their metabolites in erythrocytes

    OpenAIRE

    E Skotnicka; I Baranowska-Bosiacka; W Dudzińska; M Suska; R Nowak; K Krupecki; AJ Hłyńczak

    2008-01-01

    In this study we tried to obtain a complete overview of purine nucleotide metabolism in erythrocytes before and during an incremental, intermittent exhaustive exercise bout protocol for sportsmen (high-performance rowers) and untrained, healthy, active volunteers. Erythrocyte levels of the main nucleotides (ATP, ADP, AMP, GTP, GDP, GMP, IMP, NAD and NADP ), nucleosides (Ado, Guo, Ino) and the base Hyp were measured using the HPLC method. The parameters that can be deducted from their concent...

  11. Enzymatic Incorporation of Modified Purine Nucleotides in DNA.

    Science.gov (United States)

    Abu El Asrar, Rania; Margamuljana, Lia; Abramov, Mikhail; Bande, Omprakash; Agnello, Stefano; Jang, Miyeon; Herdewijn, Piet

    2017-12-14

    A series of nucleotide analogues, with a hypoxanthine base moiety (8-aminohypoxanthine, 1-methyl-8-aminohypoxanthine, and 8-oxohypoxanthine), together with 5-methylisocytosine were tested as potential pairing partners of N 8 -glycosylated nucleotides with an 8-azaguanine or 8-aza-9-deazaguanine base moiety by using DNA polymerases (incorporation studies). The best results were obtained with the 5-methylisocytosine nucleotide followed by the 1-methyl-8-aminohypoxanthine nucleotide. The experiments demonstrated that small differences in the structure (8-azaguanine versus 8-aza-9-deazaguanine) might lead to significant differences in recognition efficiency and selectivity, base pairing by Hoogsteen recognition at the polymerase level is possible, 8-aza-9-deazaguanine represents a self-complementary base pair, and a correlation exists between in vitro incorporation studies and in vivo recognition by natural bases in Escherichia coli, but this recognition is not absolute (exceptions were observed). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. De novo synthesis of purine nucleotides in different fiber types of rat skeletal muscle

    International Nuclear Information System (INIS)

    Tullson, P.C.; John-Alder, H.; Hood, D.A.; Terjung, R.L.

    1986-01-01

    The contribution of de novo purine nucleotide synthesis to nucleotide metabolism in skeletal muscles is not known. The authors have determined rates of de novo synthesis in soleus (slow-twitch red), red gastrocnemius (fast-twitch red), and white gastrocnemius (fast-twitch white) using the perfused rat hindquarter. 14 C glycine incorporation into ATP was linear after 1 and 2 hours of perfusion with 0.2 mM added glycine. The intracellular (I) and extracellular (E) specific activity of 14 C glycine was determined by HPLC of phenylisothiocyanate derivatives of neutralized PCA extracts. The rates of de novo synthesis when expressed relative to muscle ATP content show slow and fast-twitch red muscles to be similar and about twice as great as fast-twitch white muscles. This could represent a greater turnover of the adenine nucleotide pool in more oxidative red muscle types

  13. Imidazopyridine- and purine-thioacetamide derivatives: potent inhibitors of nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1).

    Science.gov (United States)

    Chang, Lei; Lee, Sang-Yong; Leonczak, Piotr; Rozenski, Jef; De Jonghe, Steven; Hanck, Theodor; Müller, Christa E; Herdewijn, Piet

    2014-12-11

    Nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) belongs to the family of ecto-nucleotidases, which control extracellular nucleotide, nucleoside, and (di)phosphate levels. To study the (patho)physiological roles of NPP1 potent and selective inhibitors with drug-like properties are required. Therefore, a compound library was screened for NPP1 inhibitors using a colorimetric assay with p-nitrophenyl 5'-thymidine monophosphate (p-Nph-5'-TMP) as an artificial substrate. This led to the discovery of 2-(3H-imidazo[4,5-b]pyridin-2-ylthio)-N-(3,4-dimethoxyphenyl)acetamide (5a) as a hit compound with a Ki value of 217 nM. Subsequent structure-activity relationship studies led to the development of purine and imidazo[4,5-b]pyridine analogues with high inhibitory potency (Ki values of 5.00 nM and 29.6 nM, respectively) when assayed with p-Nph-5'-TMP as a substrate. Surprisingly, the compounds were significantly less potent when tested versus ATP as a substrate, with Ki values in the low micromolar range. A prototypic inhibitor was investigated for its mechanism of inhibition and found to be competitive versus both substrates.

  14. Plasma Membrane-Located Purine Nucleotide Transport Proteins Are Key Components for Host Exploitation by Microsporidian Intracellular Parasites

    Science.gov (United States)

    Heinz, Eva; Hacker, Christian; Dean, Paul; Mifsud, John; Goldberg, Alina V.; Williams, Tom A.; Nakjang, Sirintra; Gregory, Alison; Hirt, Robert P.; Lucocq, John M.; Kunji, Edmund R. S.; Embley, T. Martin

    2014-01-01

    Microsporidia are obligate intracellular parasites of most animal groups including humans, but despite their significant economic and medical importance there are major gaps in our understanding of how they exploit infected host cells. We have investigated the evolution, cellular locations and substrate specificities of a family of nucleotide transport (NTT) proteins from Trachipleistophora hominis, a microsporidian isolated from an HIV/AIDS patient. Transport proteins are critical to microsporidian success because they compensate for the dramatic loss of metabolic pathways that is a hallmark of the group. Our data demonstrate that the use of plasma membrane-located nucleotide transport proteins (NTT) is a key strategy adopted by microsporidians to exploit host cells. Acquisition of an ancestral transporter gene at the base of the microsporidian radiation was followed by lineage-specific events of gene duplication, which in the case of T. hominis has generated four paralogous NTT transporters. All four T. hominis NTT proteins are located predominantly to the plasma membrane of replicating intracellular cells where they can mediate transport at the host-parasite interface. In contrast to published data for Encephalitozoon cuniculi, we found no evidence for the location for any of the T. hominis NTT transporters to its minimal mitochondria (mitosomes), consistent with lineage-specific differences in transporter and mitosome evolution. All of the T. hominis NTTs transported radiolabelled purine nucleotides (ATP, ADP, GTP and GDP) when expressed in Escherichia coli, but did not transport radiolabelled pyrimidine nucleotides. Genome analysis suggests that imported purine nucleotides could be used by T. hominis to make all of the critical purine-based building-blocks for DNA and RNA biosynthesis during parasite intracellular replication, as well as providing essential energy for parasite cellular metabolism and protein synthesis. PMID:25474405

  15. Plasma membrane-located purine nucleotide transport proteins are key components for host exploitation by microsporidian intracellular parasites.

    Directory of Open Access Journals (Sweden)

    Eva Heinz

    2014-12-01

    Full Text Available Microsporidia are obligate intracellular parasites of most animal groups including humans, but despite their significant economic and medical importance there are major gaps in our understanding of how they exploit infected host cells. We have investigated the evolution, cellular locations and substrate specificities of a family of nucleotide transport (NTT proteins from Trachipleistophora hominis, a microsporidian isolated from an HIV/AIDS patient. Transport proteins are critical to microsporidian success because they compensate for the dramatic loss of metabolic pathways that is a hallmark of the group. Our data demonstrate that the use of plasma membrane-located nucleotide transport proteins (NTT is a key strategy adopted by microsporidians to exploit host cells. Acquisition of an ancestral transporter gene at the base of the microsporidian radiation was followed by lineage-specific events of gene duplication, which in the case of T. hominis has generated four paralogous NTT transporters. All four T. hominis NTT proteins are located predominantly to the plasma membrane of replicating intracellular cells where they can mediate transport at the host-parasite interface. In contrast to published data for Encephalitozoon cuniculi, we found no evidence for the location for any of the T. hominis NTT transporters to its minimal mitochondria (mitosomes, consistent with lineage-specific differences in transporter and mitosome evolution. All of the T. hominis NTTs transported radiolabelled purine nucleotides (ATP, ADP, GTP and GDP when expressed in Escherichia coli, but did not transport radiolabelled pyrimidine nucleotides. Genome analysis suggests that imported purine nucleotides could be used by T. hominis to make all of the critical purine-based building-blocks for DNA and RNA biosynthesis during parasite intracellular replication, as well as providing essential energy for parasite cellular metabolism and protein synthesis.

  16. The hormonal regulation of purine biosynthesis: control of the inosinic acid branch point

    International Nuclear Information System (INIS)

    Pizzichini, M.; Di Stefano, A.; Marinello, E.; Pompucci, G.

    1986-01-01

    This paper studies the behavior of purine biosynthesis de novo in the levator animal muscle (LAM) of adult rats, before, after castration, and after testosterone administration. The incorporation of C 14-formate into the acid-soluble bases was performed as an index of the overall rate of purine nucleotide synthesis. It is shown that castration reduces the content, the specific activity of total bases and of the single bases in the LAM, indicating an inferior turnover. The increased turnover of guanylic acid, which is always present although not as much as adenylic acid, will favor the sunthesis of RNA in the sexual organs

  17. Purine nucleotide synthesis from exogenous adenine and guanine in rodent small intestine

    International Nuclear Information System (INIS)

    Gross, C.J.; Karlberg, P.K.; Savaiano, D.A.

    1986-01-01

    14 C-Adenine and 14 C-guanine uptake was studied in isolated guinea pig enterocytes. Cells were incubated in Hank's buffer and separated from the medium by centrifugation through silicone oil into 1M PCA. Uptake was temperature and concentration dependent. Both compounds were incorporated into nucleotides as measured by HPLC and HVE. Adenine was more extensively incorporated into nucleotides than was guanine. Adenine nucleotides accounted for about 70% of the intracellular label after 30 min with a majority being ADP and ATP (medium concentration = 10 μM). Guanine nucleotides accounted for only 30% of the intracellular label after 30 min. Labeled intracellular free adenine or guanine were not detected. Significantly more guanine vs. adenine was converted to uric acid. After 30 min, 11.5 +/- 3.9% (n=3) and 83.0 +/- 8.4% (n=4) of the label was present as uric acid in the medium when adenine and guanine, respectively, were the substrate. After 1 min, 34.8 +/- 3.4% (n=4) of the label in the medium was present as uric acid when guanine was the substrate. Decreasing the concentration of adenine resulted in an increase in the percent of uric acid in the medium. 14 C-adenine (75 nmol) was injected into 1 gm segments of rat jejunum. After 5 min., segments were quickly flushed and the tissue homogenized in 1M PCA. Only uric acid was present after 5 min (n=6). In contrast, in animals fasted 3 to 5 days, less conversion to uric acid was observed in the intestinal content (50-80% of the same dose was still present as adenine after 5 min) and nucleotide formation was observed in the tissue. The results indicate that uric acid and nucleotide synthesis from exogenous adenine and guanine are concentration dependent and affected by nutritional state

  18. Removal of oxygen free-radical-induced 5′,8-purine cyclodeoxynucleosides from DNA by the nucleotide excision-repair pathway in human cells

    Science.gov (United States)

    Kuraoka, Isao; Bender, Christina; Romieu, Anthony; Cadet, Jean; Wood, Richard D.; Lindahl, Tomas

    2000-01-01

    Exposure of cellular DNA to reactive oxygen species generates several classes of base lesions, many of which are removed by the base excision-repair pathway. However, the lesions include purine cyclodeoxynucleoside formation by intramolecular crosslinking between the C-8 position of adenine or guanine and the 5′ position of 2-deoxyribose. This distorting form of DNA damage, in which the purine is attached by two covalent bonds to the sugar-phosphate backbone, occurs as distinct diastereoisomers. It was observed here that both diastereoisomers block primer extension by mammalian and microbial replicative DNA polymerases, using DNA with a site-specific purine cyclodeoxynucleoside residue as template, and consequently appear to be cytotoxic lesions. Plasmid DNA containing either the 5′R or 5′S form of 5′,8-cyclo-2-deoxyadenosine was a substrate for the human nucleotide excision-repair enzyme complex. The R diastereoisomer was more efficiently repaired than the S isomer. No correction of the lesion by direct damage reversal or base excision repair was detected. Dual incision around the lesion depended on the core nucleotide excision-repair protein XPA. In contrast to several other types of oxidative DNA damage, purine cyclodeoxynucleosides are chemically stable and would be expected to accumulate at a slow rate over many years in the DNA of nonregenerating cells from xeroderma pigmentosum patients. High levels of this form of DNA damage might explain the progressive neurodegeneration seen in XPA individuals. PMID:10759556

  19. Nitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hiroyuki; Fukao, Taishi; Minami, Hirotake; Ukai, Masatoshi [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588 (Japan); Fujii, Kentaro; Yokoya, Akinari [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Fukuda, Yoshihiro; Saitoh, Yuji [Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Sayo-gun, Hyougo 679-5148 (Japan)

    2014-08-07

    The N K-edge X-ray absorption near edge structure (XANES) spectra of the purine-containing nucleotide, guanosine 5{sup ′}-monophosphate (GMP), in aqueous solution are measured under various pH conditions. The spectra show characteristic peaks, which originate from resonant excitations of N 1s electrons to π* orbitals inside the guanine moiety of GMP. The relative intensities of these peaks depend on the pH values of the solution. The pH dependence is explained by the core-level shift of N atoms at specific sites caused by protonation and deprotonation. The experimental spectra are compared with theoretical spectra calculated by using density functional theory for GMP and the other purine-containing nucleotides, adenosine 5{sup ′}-monophosphate, and adenosine 5{sup ′}-triphosphate. The N K-edge XANES spectra for all of these nucleotides are classified by the numbers of N atoms with particular chemical bonding characteristics in the purine moiety.

  20. Purine 3':5'-cyclic nucleotides with the nucleobase in a syn orientation: cAMP, cGMP and cIMP.

    Science.gov (United States)

    Řlepokura, Katarzyna Anna

    2016-06-01

    Purine 3':5'-cyclic nucleotides are very well known for their role as the secondary messengers in hormone action and cellular signal transduction. Nonetheless, their solid-state conformational details still require investigation. Five crystals containing purine 3':5'-cyclic nucleotides have been obtained and structurally characterized, namely adenosine 3':5'-cyclic phosphate dihydrate, C10H12N5O6P·2H2O or cAMP·2H2O, (I), adenosine 3':5'-cyclic phosphate 0.3-hydrate, C10H12N5O6P·0.3H2O or cAMP·0.3H2O, (II), guanosine 3':5'-cyclic phosphate pentahydrate, C10H12N5O7P·5H2O or cGMP·5H2O, (III), sodium guanosine 3':5'-cyclic phosphate tetrahydrate, Na(+)·C10H11N5O7P(-)·4H2O or Na(cGMP)·4H2O, (IV), and sodium inosine 3':5'-cyclic phosphate tetrahydrate, Na(+)·C10H10N4O7P(-)·4H2O or Na(cIMP)·4H2O, (V). Most of the cyclic nucleotide zwitterions/anions [two from four cAMP present in total in (I) and (II), cGMP in (III), cGMP(-) in (IV) and cIMP(-) in (V)] are syn conformers about the N-glycosidic bond, and this nucleobase arrangement is accompanied by Crib-H...Npur hydrogen bonds (rib = ribose and pur = purine). The base orientation is tuned by the ribose pucker. An analysis of data obtained from the Cambridge Structural Database made in the context of syn-anti conformational preferences has revealed that among the syn conformers of various purine nucleotides, cyclic nucleotides and dinucleotides predominate significantly. The interactions stabilizing the syn conformation have been indicated. The inter-nucleotide contacts in (I)-(V) have been systematized in terms of the chemical groups involved. All five structures display three-dimensional hydrogen-bonded networks.

  1. Synthesis of 8-amino and 8-substituted amino derivatives of acyclic purine nucleoside and nucleotide analogs. Alkylation of 8-substituted purine bases

    Czech Academy of Sciences Publication Activity Database

    Janeba, Zlatko; Holý, Antonín

    2001-01-01

    Roč. 20, 4-7 (2001), s. 1103-1106 ISSN 1525-7770 R&D Projects: GA ČR GV203/96/K001 Institutional research plan: CEZ:AV0Z4055905 Keywords : nucleotide analogs Subject RIV: CC - Organic Chemistry Impact factor: 0.508, year: 2001

  2. Synthesis of analogues of purine nucleotides selectively labeled by tritium on the C-8 of the purine ring and evaluation of the stability of tritium label

    Czech Academy of Sciences Publication Activity Database

    Elbert, Tomáš

    2010-01-01

    Roč. 53, č. 3 (2010), s. 156-157 ISSN 0362-4803. [Workshop of the International Isotope Society - Central European Division. The Synthesis and applications of Isotopes and Isotopically Labelled Compounds /16./. 01.10.2009-02.10.2009, Bad Soden] Institutional research plan: CEZ:AV0Z40550506 Keywords : acyclic nucleotide analogues * tritium Subject RIV: CC - Organic Chemistry

  3. Ionization of Purine Tautomers in Nucleobases, Nucleosides, and Nucleotides: From the Gas Phase to the Aqueous Environment

    Czech Academy of Sciences Publication Activity Database

    Pluhařová, Eva; Jungwirth, Pavel; Bradforth, S. E.; Slavíček, P.

    2011-01-01

    Roč. 115, č. 5 (2011), s. 1294-1305 ISSN 1520-6106 R&D Projects: GA MŠk LC512; GA ČR GA203/08/0114 Grant - others:GA ČR(CZ) GA203/09/0422 Program:GA Institutional research plan: CEZ:AV0Z40550506 Keywords : DNA bases * purines * ab initio Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.696, year: 2011

  4. Regulation of nucleotide excision repair through ubiquitination

    Institute of Scientific and Technical Information of China (English)

    Jia Li; Audesh Bhat; Wei Xiao

    2011-01-01

    Nucleotide excision repair (NER) is the most versatile DNA-repair pathway in all organisms.While bacteria require only three proteins to complete the incision step of NER,eukaryotes employ about 30 proteins to complete the same step.Here we summarize recent studies demonstrating that ubiquitination,a post-translational modification,plays critical roles in regulating the NER activity either dependent on or independent of ubiquitin-proteolysis.Several NER components have been shown as targets of ubiquitination while others are actively involved in the ubiquitination process.We argue through this analysis that ubiquitination serves to coordinate various steps of NER and meanwhile connect NER with other related pathways to achieve the efficient global DNA-damage response.

  5. Multiple sclerosis: evaluation of purine nucleotide metabolism in central nervous system in association with serum levels of selected fat-soluble antioxidants.

    Science.gov (United States)

    Kuračka, Lubomír; Kalnovičová, Terézia; Kucharská, Jarmila; Turčáni, Peter

    2014-01-01

    In the pathogenesis of demyelinating diseases including multiple sclerosis (MS) an important role is played by oxidative stress. Increased energy requirements during remyelination of axons and mitochondria failure is one of the causes of axonal degeneration and disability in MS. In this context, we analyzed to what extent the increase in purine catabolism is associated with selected blood lipophilic antioxidants and if there is any association with alterations in serum levels of coenzyme Q10. Blood serum and cerebrospinal fluid (CSF) samples from 42 patients with diagnosed MS and 34 noninflammatory neurologic patients (control group) were analyzed. Compared to control group, MS patients had significantly elevated values of all purine nucleotide metabolites, except adenosine. Serum lipophilic antioxidants γ -tocopherol, β -carotene, and coenzyme Q10 for the vast majority of MS patients were deficient or moved within the border of lower physiological values. Serum levels of TBARS, marker of lipid peroxidation, were increased by 81% in the MS patients. The results indicate that the deficit of lipophilic antioxidants in blood of MS patients may have a negative impact on bioenergetics of reparative remyelinating processes and promote neurodegeneration.

  6. Distribution of 3H within purine nucleotides of Ehrlich mouse ascites tumour cells after intraabdominal injection of myo-[2-3H]inositol

    DEFF Research Database (Denmark)

    Christensen, Søren; Klenow, H.; Overgaard-Hansen, Kay

    2000-01-01

    /desorption the nucleotides were dephosphorylated, enriched with [U-14C]adenosine, and exposed to purine-nucleoside specific enzymes. Reverse phase HPLC and radioactivity measurement demonstrated that for adenosine about 82% of total stable 3H label was in ribose and thus about 18% in adenine. For guanosine about 89...

  7. Deregulation of purine pathway in Bacillus subtilis and its use in riboflavin biosynthesis

    Science.gov (United States)

    2014-01-01

    Background Purine nucleotides are essential metabolites for living organisms because they are involved in many important processes, such as nucleic acid synthesis, energy supply, and biosynthesis of several amino acids and riboflavin. Owing to the pivotal roles of purines in cell physiology, the pool of intracellular purine nucleotides must be maintained under strict control, and hence the de novo purine biosynthetic pathway is tightly regulated by transcription repression and inhibition mechanism. Deregulation of purine pathway is essential for this pathway engineering in Bacillus subtilis. Results Deregulation of purine pathway was attempted to improve purine nucleotides supply, based on a riboflavin producer B. subtilis strain with modification of its rib operon. To eliminate transcription repression, the pur operon repressor PurR and the 5’-UTR of pur operon containing a guanine-sensing riboswitch were disrupted. Quantitative RT-PCR analysis revealed that the relative transcription levels of purine genes were up-regulated about 380 times. Furthermore, site-directed mutagenesis was successfully introduced into PRPP amidotransferase (encoded by purF) to remove feedback inhibition by homologous alignment and analysis. Overexpression of the novel mutant PurF (D293V, K316Q and S400W) significantly increased PRPP amidotransferase activity and triggered a strong refractory effect on purine nucleotides mediated inhibition. Intracellular metabolite target analysis indicated that the purine nucleotides supply in engineered strains was facilitated by a stepwise gene-targeted deregulation. With these genetic manipulations, we managed to enhance the metabolic flow through purine pathway and consequently increased riboflavin production 3-fold (826.52 mg/L) in the purF-VQW mutant strain. Conclusions A sequential optimization strategy was applied to deregulate the rib operon and purine pathway of B. subtilis to create genetic diversities and to improve riboflavin production

  8. Enzymatic production of dietary nucleotides from low-soluble purine bases by an efficient, thermostable and alkali-tolerant biocatalyst.

    Science.gov (United States)

    Del Arco, J; Cejudo-Sanches, J; Esteban, I; Clemente-Suárez, V J; Hormigo, D; Perona, A; Fernández-Lucas, J

    2017-12-15

    Traditionally, enzymatic synthesis of nucleoside-5'-monophosphates (5'-NMPs) using low water-soluble purine bases has been described as less efficient due to their low solubility in aqueous media. The use of enzymes from extremophiles, such as thermophiles or alkaliphiles, offers the potential to increase solubilisation of these bases by employing high temperatures or alkaline pH. This study describes the cloning, expression and purification of hypoxanthine-guanine-xanthine phosphoribosyltransferase from Thermus thermophilus (TtHGXPRT). Biochemical characterization indicates TtHGXPRT as a homotetramer with excellent activity and stability across a broad range of temperatures (50-90°C) and ionic strengths (0-500mMNaCl), but it also reveals an unusually high activity and stability under alkaline conditions (pH range 8-11). In order to explore the potential of TtHGXPRT as an industrial biocatalyst, enzymatic production of several dietary 5'-NMPs, such as 5'-GMP and 5'-IMP, was carried out at high concentrations of guanine and hypoxanthine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. [Features of influence adenosine, AMP and hyperadrenalinemiya on the immune status, metabolic enzymes of purine nucleotides and the antioxidant defense system].

    Science.gov (United States)

    Tapbergenov, S O; Sovetov, B S; Tapbergenov, A T

    2016-11-01

    Administration of a large dose of adrenaline (4 mg/kg 60 min before analysis) increased blood levels of total leukocytes, lymphocytes, decreased T-cell suppressors, leukocyte migration inhibition reaction (LMIR) and NBT test, but increased the level of conjugated dienes (CD). Administration of AMPand adenosine increased levels of total leukocytes, lymphocytes, T- lymphocytes, T-helpers, decreased the level of malondialdehyde (MDA), LMIR, and T-cell suppressors. Sympathetic hyperactivation induced by administration of a large dose of adrenaline (4 mg/kg 60 min before analysis) was accompanied by an increase in heart and liver activities of glutathione peroxidase (GPx), catalase, AMP deaminase (AMPD), and adenosine deaminase (AD). Administration of AMP or adenosine caused a decrease in activities of glutathione reductase (GR), GPx, catalase, a decrease in the MDA level and an increase in activities of AMPD and AD in the heart. In the liver AMP and adenosine also caused a decrease in activities of glutathione reductase (GR), GPx, a decrease in the MDA level and an increase in activities of AMPD and AD. The data obtained suggest that administration of adrenaline, AMP, and adenosine influences activity of enzymes involved in purine nucleotide metabolism. However, in contrast to adrenaline, administration of AMP or adenosine does not provoke stress reaction.

  10. Nucleotide sequence, transcript mapping, and regulation of the RAD2 gene of Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Madura, K.; Prakash, S.

    1986-01-01

    The authors determined the nucleotide sequence, mapped the 5' and 3' nRNA termini, and examined the regulation of the RAD2 gene of Saccharomyces cerevisiae. A long open reading frame within the RAD2 transcribed region encodes a protein of 1031 amino acids with a calculated molecular weight of 117,847. A disruption of the RAD2 gene that deletes the 78 carboxyl terminal codons results in loss of RAD2 function. The 5' ends of RAD2 mRNA show considerable heterogeneity, mapping 5 to 62 nucleotides upstream of the first ATG codon of the long RAD2 open reading frame. The longest RAD2 transcripts also contain a short open reading frame of 37 codons that precedes and overlaps the 5' end of the long RAD2 open reading frame. The RAD2 3' nRNA end maps 171 nucleotides downstream of the TAA termination codon and 20 nucleotides downstream from a 12-base-pair inverted repeat that might function in transcript termination. Northern blot analysis showed a ninefold increase in steady-state levels of RAD2 mRNA after treatment of yeast cells with UV light. The 5' flanking region of the RAD2 gene contains several direct and inverted repeats and a 44-nuclotide-long purine-rich tract. The sequence T G G A G G C A T T A A found at position - 167 to -156 in the RAD2 gene is similar to at sequence present in the 5' flanking regions of the RAD7 and RAD10 genes

  11. Cross-coupling reactions of unprotected halopurine bases, nucleosides, nucleotides and nucleoside triphosphates with 4-boronophenylalanine in water. Synthesis of (purin-8-yl)- and (purin-6-yl)phenylalanines

    Czech Academy of Sciences Publication Activity Database

    Čapek, Petr; Pohl, Radek; Hocek, Michal

    2006-01-01

    Roč. 4, č. 11 (2006), s. 2278-2284 ISSN 1477-0520 R&D Projects: GA AV ČR(CZ) 1QS400550501; GA MŠk(CZ) 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : amino acids * purines * nucleosides * cross-coupling reactions Subject RIV: CC - Organic Chemistry Impact factor: 2.874, year: 2006

  12. Synthesis and spectroscopy of clay intercalated Cu(II) bio-monomer complexes: coordination of Cu(II) with purines and nucleotides

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Leeman, H.; Schoonheydt, R.A.

    1999-01-01

    The spectroscopic properties of Cu(bio-monomer)nm+ complexes [BM=bio-monomer (purine, adenine, guanine, hypoxanthine, 5-ADP and 5-GMP)] in saponite clays have been investigated by diffuse reflectance spectroscopy (DRS) in the UV-Vis-NIR region and electron paramagnetic resonance (EPR) at X-band.

  13. Multiple Sclerosis: Evaluation of Purine Nucleotide Metabolism in Central Nervous System in Association with Serum Levels of Selected Fat-Soluble Antioxidants

    OpenAIRE

    Kuračka, Ľubomír; Kalnovičová, Terézia; Kucharská, Jarmila; Turčáni, Peter

    2014-01-01

    In the pathogenesis of demyelinating diseases including multiple sclerosis (MS) an important role is played by oxidative stress. Increased energy requirements during remyelination of axons and mitochondria failure is one of the causes of axonal degeneration and disability in MS. In this context, we analyzed to what extent the increase in purine catabolism is associated with selected blood lipophilic antioxidants and if there is any association with alterations in serum levels of coenzyme Q10....

  14. Synthesis of carbon-11-labeled imidazopyridine- and purine-thioacetamide derivatives as new potential PET tracers for imaging of nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1).

    Science.gov (United States)

    Gao, Mingzhang; Wang, Min; Zheng, Qi-Huang

    2016-03-01

    The target tracer carbon-11-labeled imidazopyridine- and purine-thioacetamide derivatives, N-(3-[(11)C]methoxy-4-methoxyphenyl)-2-((5-methoxy-3H-imidazo[4,5-b]pyridin-2-yl)thio)acetamide (3-[(11)C]4a) and N-(4-[(11)C]methoxy-3-methoxyphenyl)-2-((5-methoxy-3H-imidazo[4,5-b]pyridin-2-yl)thio)acetamide (4-[(11)C]4a); 2-((6-amino-9H-purin-8-yl)thio)-N-(3-[(11)C]methoxy-4-methoxyphenyl)acetamide (3-[(11)C]8a) and 2-((6-amino-9H-purin-8-yl)thio)-N-(4-[(11)C]methoxy-3-methoxyphenyl)acetamide (4-[(11)C]8a), were prepared by O-[(11)C]methylation of their corresponding precursors with [(11)C]CH3OTf under basic condition (2N NaOH) and isolated by a simplified solid-phase extraction (SPE) method in 50-60% radiochemical yields based on [(11)C]CO2 and decay corrected to end of bombardment (EOB). The overall synthesis time from EOB was 23min, the radiochemical purity was >99%, and the specific activity at end of synthesis (EOS) was 185-555GBq/μmol. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Regulation of Cell Wall Plasticity by Nucleotide Metabolism in Lactococcus lactis*

    Science.gov (United States)

    Solopova, Ana; Formosa-Dague, Cécile; Courtin, Pascal; Furlan, Sylviane; Veiga, Patrick; Péchoux, Christine; Armalyte, Julija; Sadauskas, Mikas; Kok, Jan; Hols, Pascal; Dufrêne, Yves F.; Kuipers, Oscar P.; Chapot-Chartier, Marie-Pierre; Kulakauskas, Saulius

    2016-01-01

    To ensure optimal cell growth and separation and to adapt to environmental parameters, bacteria have to maintain a balance between cell wall (CW) rigidity and flexibility. This can be achieved by a concerted action of peptidoglycan (PG) hydrolases and PG-synthesizing/modifying enzymes. In a search for new regulatory mechanisms responsible for the maintenance of this equilibrium in Lactococcus lactis, we isolated mutants that are resistant to the PG hydrolase lysozyme. We found that 14% of the causative mutations were mapped in the guaA gene, the product of which is involved in purine metabolism. Genetic and transcriptional analyses combined with PG structure determination of the guaA mutant enabled us to reveal the pivotal role of the pyrB gene in the regulation of CW rigidity. Our results indicate that conversion of l-aspartate (l-Asp) to N-carbamoyl-l-aspartate by PyrB may reduce the amount of l-Asp available for PG synthesis and thus cause the appearance of Asp/Asn-less stem peptides in PG. Such stem peptides do not form PG cross-bridges, resulting in a decrease in PG cross-linking and, consequently, reduced PG thickness and rigidity. We hypothesize that the concurrent utilization of l-Asp for pyrimidine and PG synthesis may be part of the regulatory scheme, ensuring CW flexibility during exponential growth and rigidity in stationary phase. The fact that l-Asp availability is dependent on nucleotide metabolism, which is tightly regulated in accordance with the growth rate, provides L. lactis cells the means to ensure optimal CW plasticity without the need to control the expression of PG synthesis genes. PMID:27022026

  16. Effects of hypokinesia on cyclic nucleotides and hormonal regulation ...

    African Journals Online (AJOL)

    PTH), calcitonin (CT), cyclic nucleotides (cAMP, cGMP) and calcium in the blood of rats, while in urine - phosphate, calcium and cyclic nucleotides. Design: Laboratory based experiment. Setting: Laboratory in the Department of Biochemistry, ...

  17. Anion-exchange analysis of isotopically labelled nucleotides, nucleosides, and bases in metabolic disorders

    International Nuclear Information System (INIS)

    Nissinen, E.A.O.

    1987-01-01

    This paper on the importance of cellular purines and pyrimidines is evidenced by the multitude of diseases, such as hyperuricemia, orotic aciduria, gout, Lesch-Nyhan syndrome, immunodeficiencies with B- and T-cell dysfunctions, etc. which result from aberrant metabolism. In addition, the use of purine and pyrimidine analogs in chemotherapy is of growing interest. Purine metabolism consists of a complex network of biochemical pathway. These pathways are under complicated feedback regulation and there also exists a close relationship between purine and pyrimidine metabolism. In addition, these pathways interact with those of the carbohydrate, amino acid, and energy metabolism. Since metabolic pathways are closely interrelated, a change in the concentration of a particular metabolite may lead to many changes in the overall metabolic profiles. For instance, in the area of nucleotide metabolism, the inhibition of IMP dehydrogenase by mycophenolic acid leads to various changes in both purine and pyrimidine nucleotide pools. Inhibition of de nova purine biosynthesis by methotrexate leads to many changes in purine and pyrimidine ribonucleotides and deoxyribonucleotides. Thus, the simultaneous measurement of all cellular purine and pyrimidine metabolites from individuals whose metabolism is altered, either by a metabolic disease or by the action of drugs, may further our understanding of cellular metabolism

  18. Changes by short-term hypoxia in the membrane properties of pyramidal cells and the levels of purine and pyrimidine nucleotides in slices of rat neocortex; effects of agonists and antagonists of ATP-dependent potassium channels.

    Science.gov (United States)

    Pissarek, M; Garcia de Arriba, S; Schäfer, M; Sieler, D; Nieber, K; Illes, P

    1998-10-01

    - to diphosphate ratios progressively declined for ATP/ADP and GTP/GDP, but not for UTP/UDP when the duration of hypoxia was increased from 5 to 30 min. Hence, the rapid fall in the ratios of nucleoside tri- to diphosphates without the induction of a potassium current failed to indicate an allosteric regulation of a plasmalemmal K(ATP) channel by purine and pyrimidine nucleotides. Diazoxide had no effect on neocortical pyramidal neurons and was effective only in combination with a hypoxic stimulus; it is suggested that both plasmalemmal and mitochondrial K(ATP) channels are involved under these conditions. The hypoxic depolarization may be due to blockade of K+,Na+-ATPase by limitation of energy supplying substrate.

  19. Metabolic Reprogramming During Purine Stress in the Protozoan Pathogen Leishmania donovani

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Jessica L.; Yates, Phillip A.; Soysa, Radika; Alfaro, Joshua F.; Yang, Feng; Burnum-Johnson, Kristin E.; Petyuk, Vladislav A.; Weitz, Karl K.; Camp, David G.; Smith, Richard D.; Wilmarth, Phillip A.; David, Larry L.; Ramasamy, Gowthaman; Myler, Peter J.; Carter, Nicola S.

    2014-02-27

    The ability of Leishmania to survive in their insect or mammalian host is dependent upon an ability to sense and adapt to changes in the microenvironment. However, little is known about the molecular mechanisms underlying the parasite response to environmental changes, such as nutrient availability. To elucidate nutrient stress response pathways in Leishmania donovani, we have used purine starvation as the paradigm. The salvage of purines from the host milieu is obligatory for parasite replication; nevertheless, purine-starved parasites can persist in culture without supplementary purine for over 3 months, indicating that the response to purine starvation is robust and engenders parasite survival under conditions of extreme scarcity. To understand metabolic reprogramming during purine starvation we have employed global approaches. Whole proteome comparisons between purine-starved and purine-replete parasites over a 6-48 h span have revealed a temporal and coordinated response to purine starvation. Purine transporters and enzymes involved in acquisition at the cell surface are upregulated within a few hours of purine removal from the media, while other key purine salvage components are upregulated later in the time-course and more modestly. After 48 h, the proteome of purine-starved parasites is extensively remodeled and adaptations to purine stress appear tailored to deal with both purine deprivation and general stress. To probe the molecular mechanisms affecting proteome remodeling in response to purine starvation, comparative RNA-seq analyses, qRT-PCR, and luciferase reporter assays were performed on purine-starved versus purine-replete parasites. While the regulation of a minority of proteins tracked with changes at the mRNA level, for many regulated proteins it appears that proteome remodeling during purine stress occurs primarily via translational and/or post-translational mechanisms.

  20. Regulation of Ca2+ release from mitochondria by the oxidation-reduction state of pyridine nucleotides

    Science.gov (United States)

    Lehninger, Albert L.; Vercesi, Anibal; Bababunmi, Enitan A.

    1978-01-01

    Mitochondria from normal rat liver and heart, and also Ehrlich tumor cells, respiring on succinate as energy source in the presence of rotenone (to prevent net electron flow to oxygen from the endogenous pyridine nucleotides), rapidly take up Ca2+ and retain it so long as the pyridine nucleotides are kept in the reduced state. When acetoacetate is added to bring the pyridine nucleotides into a more oxidized state, Ca2+ is released to the medium. A subsequent addition of a reductant of the pyridine nucleotides such as β-hydroxybutyrate, glutamate, or isocitrate causes reuptake of the released Ca2+. Successive cycles of Ca2+ release and uptake can be induced by shifting the redox state of the pyridine nucleotides to more oxidized and more reduced states, respectively. Similar observations were made when succinate oxidation was replaced as energy source by ascorbate oxidation or by the hydrolysis of ATP. These and other observations form the basis of a hypothesis for feedback regulation of Ca2+-dependent substrate- or energy-mobilizing enzymatic reactions by the uptake or release of mitochondrial Ca2+, mediated by the cytosolic phosphate potential and the ATP-dependent reduction of mitochondrial pyridine nucleotides by reversal of electron transport. Images PMID:25436

  1. Cytosolic nucleotides block and regulate the Arabidopsis vacuolar anion channel AtALMT9.

    Science.gov (United States)

    Zhang, Jingbo; Martinoia, Enrico; De Angeli, Alexis

    2014-09-12

    The aluminum-activated malate transporters (ALMTs) form a membrane protein family exhibiting different physiological roles in plants, varying from conferring tolerance to environmental Al(3+) to the regulation of stomatal movement. The regulation of the anion channels of the ALMT family is largely unknown. Identifying intracellular modulators of the activity of anion channels is fundamental to understanding their physiological functions. In this study we investigated the role of cytosolic nucleotides in regulating the activity of the vacuolar anion channel AtALMT9. We found that cytosolic nucleotides modulate the transport activity of AtALMT9. This modulation was based on a direct block of the pore of the channel at negative membrane potentials (open channel block) by the nucleotide and not by a phosphorylation mechanism. The block by nucleotides of AtALMT9-mediated currents was voltage dependent. The blocking efficiency of intracellular nucleotides increased with the number of phosphate groups and ATP was the most effective cellular blocker. Interestingly, the ATP block induced a marked modification of the current-voltage characteristic of AtALMT9. In addition, increased concentrations of vacuolar anions were able to shift the ATP block threshold to a more negative membrane potential. The block of AtALMT9-mediated anion currents by ATP at negative membrane potentials acts as a gate of the channel and vacuolar anion tune this gating mechanism. Our results suggest that anion transport across the vacuolar membrane in plant cells is controlled by cytosolic nucleotides and the energetic status of the cell. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Cytosolic Nucleotides Block and Regulate the Arabidopsis Vacuolar Anion Channel AtALMT9*

    Science.gov (United States)

    Zhang, Jingbo; Martinoia, Enrico; De Angeli, Alexis

    2014-01-01

    The aluminum-activated malate transporters (ALMTs) form a membrane protein family exhibiting different physiological roles in plants, varying from conferring tolerance to environmental Al3+ to the regulation of stomatal movement. The regulation of the anion channels of the ALMT family is largely unknown. Identifying intracellular modulators of the activity of anion channels is fundamental to understanding their physiological functions. In this study we investigated the role of cytosolic nucleotides in regulating the activity of the vacuolar anion channel AtALMT9. We found that cytosolic nucleotides modulate the transport activity of AtALMT9. This modulation was based on a direct block of the pore of the channel at negative membrane potentials (open channel block) by the nucleotide and not by a phosphorylation mechanism. The block by nucleotides of AtALMT9-mediated currents was voltage dependent. The blocking efficiency of intracellular nucleotides increased with the number of phosphate groups and ATP was the most effective cellular blocker. Interestingly, the ATP block induced a marked modification of the current-voltage characteristic of AtALMT9. In addition, increased concentrations of vacuolar anions were able to shift the ATP block threshold to a more negative membrane potential. The block of AtALMT9-mediated anion currents by ATP at negative membrane potentials acts as a gate of the channel and vacuolar anion tune this gating mechanism. Our results suggest that anion transport across the vacuolar membrane in plant cells is controlled by cytosolic nucleotides and the energetic status of the cell. PMID:25028514

  3. Nucleotide Metabolism and its Control in Lactic Acid Bacteria

    DEFF Research Database (Denmark)

    Kilstrup, Mogens; Hammer, Karin; Jensen, Peter Ruhdal

    2005-01-01

    Most metabolic reactions are connected through either their utilization of nucleotides or their utilization of nucleotides or their regulation by these metabolites. In this review the biosynthetic pathways for pyrimidine and purine metabolism in lactic acid bacteria are described including...... the interconversion pathways, the formation of deoxyribonucleotides and the salvage pathways for use of exogenous precursors. The data for the enzymatic and the genetic regulation of these pathways are reviewed, as well as the gene organizations in different lactic acid bacteria. Mutant phenotypes and methods...... for manipulation of nucleotide pools are also discussed. Our aim is to provide an overview of the physiology and genetics of nucleotide metabolism and its regulation that will facilitate the interpretation of data arising from genetics, metabolomics, proteomics, and transcriptomics in lactic acid bacteria....

  4. A single nucleotide change affects fur-dependent regulation of sodB in H. pylori.

    Directory of Open Access Journals (Sweden)

    Beth M Carpenter

    Full Text Available Helicobacter pylori is a significant human pathogen that has adapted to survive the many stresses found within the gastric environment. Superoxide Dismutase (SodB is an important factor that helps H. pylori combat oxidative stress. sodB was previously shown to be repressed by the Ferric Uptake Regulator (Fur in the absence of iron (apo-Fur regulation [1]. Herein, we show that apo regulation is not fully conserved among all strains of H. pylori. apo-Fur dependent changes in sodB expression are not observed under iron deplete conditions in H. pylori strains G27, HPAG1, or J99. However, Fur regulation of pfr and amiE occurs as expected. Comparative analysis of the Fur coding sequence between G27 and 26695 revealed a single amino acid difference, which was not responsible for the altered sodB regulation. Comparison of the sodB promoters from G27 and 26695 also revealed a single nucleotide difference within the predicted Fur binding site. Alteration of this nucleotide in G27 to that of 26695 restored apo-Fur dependent sodB regulation, indicating that a single base difference is at least partially responsible for the difference in sodB regulation observed among these H. pylori strains. Fur binding studies revealed that alteration of this single nucleotide in G27 increased the affinity of Fur for the sodB promoter. Additionally, the single base change in G27 enabled the sodB promoter to bind to apo-Fur with affinities similar to the 26695 sodB promoter. Taken together these data indicate that this nucleotide residue is important for direct apo-Fur binding to the sodB promoter.

  5. Guanine nucleotide regulation of α1-adrenergic receptors of muscle and kidney eptihelial cells

    International Nuclear Information System (INIS)

    Terman, B.I.; Hughes, R.J.; Slivka, S.R.; Insel, P.A.

    1986-01-01

    The authors have examined the effect of guanine nucleotides on the interaction of adrenergic agents with α 1 -adrenergic receptors of two cell lines, the Madin-Darby Canine Kidney (MDCK) and BC3H-1 muscle cells. While gaunylylimidodiphosphoate (Gpp(NH)p) had no effect on the affinity or the total number of [ -3 H]prazosin binding sites in membranes prepared from these cells, the nucleotide decreased the apparent affinity of the agonist epinephrine in competing for [ 3 H]prazosin binding sites in both cell types. The EC 50 of Gpp(NH)p was ∼100 μM, and a maximal effect was seen at 500 μM. In contrast, 100 μM Gpp(NH)p yielding maximal shifts in binding of epinephrine to β-adrenergic receptors in BC3H-1 cell membranes. Guanine nucleotides were significantly more effective than adenine nucleotides in shifting agonist affinity for the α 1 -receptor and Mg ++ was required to observe a maximal effect. α 1 -receptor agonists activated phosphatidylinositol (PI) hydrolysis in both cell types, but have no direct effect on membrane adenylate cyclase activity. In intact BC3H-1 cells, α 1 -agonists inhibited β-adrenergic cAMP production, an effect which appears in preliminary studies not to result from enhanced phosphodieterase activity. These results show that agonist binding to α 1 -adrenergic receptors in mammalian kidney and muscle cells is regulated by guanine nucleotides. This regulation and inturn transmembrane signalling (PI hydrolysis) by these receptors appear to involve a guanine nucleotide binding (G) protein, which may be different than G/sub s/ and G/sub i/

  6. A generalized allosteric mechanism for cis-regulated cyclic nucleotide binding domains.

    Directory of Open Access Journals (Sweden)

    Alexandr P Kornev

    2008-04-01

    Full Text Available Cyclic nucleotides (cAMP and cGMP regulate multiple intracellular processes and are thus of a great general interest for molecular and structural biologists. To study the allosteric mechanism of different cyclic nucleotide binding (CNB domains, we compared cAMP-bound and cAMP-free structures (PKA, Epac, and two ionic channels using a new bioinformatics method: local spatial pattern alignment. Our analysis highlights four major conserved structural motifs: 1 the phosphate binding cassette (PBC, which binds the cAMP ribose-phosphate, 2 the "hinge," a flexible helix, which contacts the PBC, 3 the beta(2,3 loop, which provides precise positioning of an invariant arginine from the PBC, and 4 a conserved structural element consisting of an N-terminal helix, an eight residue loop and the A-helix (N3A-motif. The PBC and the hinge were included in the previously reported allosteric model, whereas the definition of the beta(2,3 loop and the N3A-motif as conserved elements is novel. The N3A-motif is found in all cis-regulated CNB domains, and we present a model for an allosteric mechanism in these domains. Catabolite gene activator protein (CAP represents a trans-regulated CNB domain family: it does not contain the N3A-motif, and its long range allosteric interactions are substantially different from the cis-regulated CNB domains.

  7. AMPD2 regulates GTP synthesis and is mutated in a potentially treatable neurodegenerative brainstem disorder.

    Science.gov (United States)

    Akizu, Naiara; Cantagrel, Vincent; Schroth, Jana; Cai, Na; Vaux, Keith; McCloskey, Douglas; Naviaux, Robert K; Van Vleet, Jeremy; Fenstermaker, Ali G; Silhavy, Jennifer L; Scheliga, Judith S; Toyama, Keiko; Morisaki, Hiroko; Sonmez, Fatma M; Celep, Figen; Oraby, Azza; Zaki, Maha S; Al-Baradie, Raidah; Faqeih, Eissa A; Saleh, Mohammed A M; Spencer, Emily; Rosti, Rasim Ozgur; Scott, Eric; Nickerson, Elizabeth; Gabriel, Stacey; Morisaki, Takayuki; Holmes, Edward W; Gleeson, Joseph G

    2013-08-01

    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 deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH) due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a potentially treatable early-onset neurodegenerative disease. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. AMPD2 Regulates GTP Synthesis and is Mutated in a Potentially-Treatable Neurodegenerative Brainstem Disorder

    Science.gov (United States)

    Akizu, Naiara; Cantagrel, Vincent; Schroth, Jana; Cai, Na; Vaux, Keith; McCloskey, Douglas; Naviaux, Robert K.; Vleet, Jeremy Van; Fenstermaker, Ali G.; Silhavy, Jennifer L.; Scheliga, Judith S.; Toyama, Keiko; Morisaki, Hiroko; Sonmez, Fatma Mujgan; Celep, Figen; Oraby, Azza; Zaki, Maha S.; Al-Baradie, Raidah; Faqeih, Eissa; Saleh, Mohammad; Spencer, Emily; Rosti, Rasim Ozgur; Scott, Eric; Nickerson, Elizabeth; Gabriel, Stacey; Morisaki, Takayuki; Holmes, Edward W.; Gleeson, Joseph G.

    2013-01-01

    Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acids synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenosine and guanine nucleotides. We describe a new distinct early-onset neurodegenerative condition resulting from mutations in the adenosine monophosphate deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH), due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a new, potentially treatable early-onset neurodegenerative disease. PMID:23911318

  9. Transcriptional and post-transcriptional regulation of nucleotide excision repair genes in human cells

    Energy Technology Data Exchange (ETDEWEB)

    Lefkofsky, Hailey B. [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Veloso, Artur [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Bioinformatics Program, Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI (United States); Ljungman, Mats, E-mail: ljungman@umich.edu [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI (United States)

    2015-06-15

    Nucleotide excision repair (NER) removes DNA helix-distorting lesions induced by UV light and various chemotherapeutic agents such as cisplatin. These lesions efficiently block the elongation of transcription and need to be rapidly removed by transcription-coupled NER (TC-NER) to avoid the induction of apoptosis. Twenty-nine genes have been classified to code for proteins participating in nucleotide excision repair (NER) in human cells. Here we explored the transcriptional and post-transcriptional regulation of these NER genes across 13 human cell lines using Bru-seq and BruChase-seq, respectively. Many NER genes are relatively large in size and therefore will be easily inactivated by UV-induced transcription-blocking lesions. Furthermore, many of these genes produce transcripts that are rather unstable. Thus, these genes are expected to rapidly lose expression leading to a diminished function of NER. One such gene is ERCC6 that codes for the CSB protein critical for TC-NER. Due to its large gene size and high RNA turnover rate, the ERCC6 gene may act as dosimeter of DNA damage so that at high levels of damage, ERCC6 RNA levels would be diminished leading to the loss of CSB expression, inhibition of TC-NER and the promotion of cell death.

  10. Transcriptional and Posttranslational Regulation of Nucleotide Excision Repair: The Guardian of the Genome against Ultraviolet Radiation

    Directory of Open Access Journals (Sweden)

    Jeong-Min Park

    2016-11-01

    Full Text Available Ultraviolet (UV radiation from sunlight represents a constant threat to genome stability by generating modified DNA bases such as cyclobutane pyrimidine dimers (CPD and pyrimidine-pyrimidone (6-4 photoproducts (6-4PP. If unrepaired, these lesions can have deleterious effects, including skin cancer. Mammalian cells are able to neutralize UV-induced photolesions through nucleotide excision repair (NER. The NER pathway has multiple components including seven xeroderma pigmentosum (XP proteins (XPA to XPG and numerous auxiliary factors, including ataxia telangiectasia and Rad3-related (ATR protein kinase and RCC1 like domain (RLD and homologous to the E6-AP carboxyl terminus (HECT domain containing E3 ubiquitin protein ligase 2 (HERC2. In this review we highlight recent data on the transcriptional and posttranslational regulation of NER activity.

  11. The regulated secretory pathway and human disease: insights from gene variants and single nucleotide polymorphisms

    Directory of Open Access Journals (Sweden)

    Stephen eSalton

    2013-08-01

    Full Text Available The regulated secretory pathway provides critical control of peptide, growth factor, and hormone release from neuroendocrine and endocrine cells, and neurons, maintaining physiological homeostasis. Propeptides and prohormones are packaged into dense core granules (DCGs, where they frequently undergo tissue-specific processing as the DCG matures. Proteins of the granin family are DCG components, and although their function is not fully understood, data suggest they are involved in DCG formation and regulated protein/peptide secretion, in addition to their role as precursors of bioactive peptides. Association of gene variation, including single nucleotide polymorphisms (SNPs, with neuropsychiatric, endocrine and metabolic diseases, has implicated specific secreted proteins and peptides in disease pathogenesis. For example, a SNP at position 196 (G/A of the human brain-derived neurotrophic factor (BDNF gene dysregulates protein processing and secretion and leads to cognitive impairment. This suggests more generally that variants identified in genes encoding secreted growth factors, peptides, hormones, and proteins involved in DCG biogenesis, protein processing, and the secretory apparatus, could provide insight into the process of regulated secretion as well as disorders that result when it is impaired.

  12. Pediatric neurological syndromes and inborn errors of purine metabolism.

    Science.gov (United States)

    Camici, Marcella; Micheli, Vanna; Ipata, Piero Luigi; Tozzi, Maria Grazia

    2010-02-01

    This review is devised to gather the presently known inborn errors of purine metabolism that manifest neurological pediatric syndromes. The aim is to draw a comprehensive picture of these rare diseases, characterized by unexpected and often devastating neurological symptoms. Although investigated for many years, most purine metabolism disorders associated to psychomotor dysfunctions still hide the molecular link between the metabolic derangement and the neurological manifestations. This basically indicates that many of the actual functions of nucleosides and nucleotides in the development and function of several organs, in particular central nervous system, are still unknown. Both superactivity and deficiency of phosphoribosylpyrophosphate synthetase cause hereditary disorders characterized, in most cases, by neurological impairments. The deficiency of adenylosuccinate lyase and 5-amino-4-imidazolecarboxamide ribotide transformylase/IMP cyclohydrolase, both belonging to the de novo purine synthesis pathway, is also associated to severe neurological manifestations. Among catabolic enzymes, hyperactivity of ectosolic 5'-nucleotidase, as well as deficiency of purine nucleoside phosphorylase and adenosine deaminase also lead to syndromes affecting the central nervous system. The most severe pathologies are associated to the deficiency of the salvage pathway enzymes hypoxanthine-guanine phosphoribosyltransferase and deoxyguanosine kinase: the former due to an unexplained adverse effect exerted on the development and/or differentiation of dopaminergic neurons, the latter due to a clear impairment of mitochondrial functions. The assessment of hypo- or hyperuricemic conditions is suggestive of purine enzyme dysfunctions, but most disorders of purine metabolism may escape the clinical investigation because they are not associated to these metabolic derangements. This review may represent a starting point stimulating both scientists and physicians involved in the study of

  13. DMPD: Critical role of toll-like receptors and nucleotide oligomerisation domain inthe regulation of health and disease. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available and nucleotide oligomerisation domain inthe regulation of health and disease. Pu...bmedID 17535871 Title Critical role of toll-like receptors and nucleotide oligomerisation domain inthe regulation of health...17535871 Critical role of toll-like receptors and nucleotide oligomerisation domain inthe regulation of heal...th and disease. Mitchell JA, Paul-Clark MJ, Clarke GW, McMaster SK, Cartwright N. J

  14. Cyclic nucleotide dependent dephosphorylation of regulator of G-protein signaling 18 in human platelets.

    LENUS (Irish Health Repository)

    Gegenbauer, Kristina

    2013-11-01

    Regulator of G-protein signaling 18 (RGS18) is a GTPase-activating protein that turns off Gq signaling in platelets. RGS18 is regulated by binding to the adaptor protein 14-3-3 via phosphorylated serine residues S49 and S218 on RGS18. In this study we confirm that thrombin, thromboxane A2, or ADP stimulate the interaction of RGS18 and 14-3-3 by increasing the phosphorylation of S49. Cyclic AMP- and cyclic GMP-dependent kinases (PKA, PKG) inhibit the interaction of RGS18 and 14-3-3 by phosphorylating S216. To understand the effect of S216 phosphorylation we studied the phosphorylation kinetics of S49, S216, and S218 using Phos-tag gels and phosphorylation site-specific antibodies in transfected cells and in platelets. Cyclic nucleotide-induced detachment of 14-3-3 from RGS18 coincides initially with double phosphorylation of S216 and S218. This is followed by dephosphorylation of S49 and S218. Dephosphorylation of S49 and S218 might be mediated by protein phosphatase 1 (PP1) which is linked to RGS18 by the regulatory subunit PPP1R9B (spinophilin). We conclude that PKA and PKG induced S216 phosphorylation triggers the dephosphorylation of the 14-3-3 binding sites of RGS18 in platelets.

  15. Señales purinérgicas Purinergic signals

    Directory of Open Access Journals (Sweden)

    Eduardo R Lazarowski

    2009-04-01

    Full Text Available En la última década se ha aportado clara evidencia de que tanto nucleósidos como nucleótidos de adenina y uridina pueden funcionar como factores de señalización extracelular. Su acción es mediada por dos tipos principales de receptores de superficie denominados purinérgicos. Los receptores P1 se activan por adenosina, y son todos metabotrópicos, mientras que los receptores de nucleótidos (ATP, ADP, UTP y UDP y nucleótidos-azúcares (UDP-glucosa y UDP-galactosa pueden ser metabotrópicos (P2Y o ionotrópicos (P2X. La importancia y complejidad de este sistema de señalización se evidencia por la diversidad de mecanismos de liberación de nucleótidos al medio extracelular y por la distribución ubicua de varios grupos de ectonucleotidasas capaces de catalizar la degradación y conversión de nucleótidos. Hasta el momento se han descrito y clonado una veintena de estos receptores que modulan una variedad de respuestas, como el impulso nervioso, la respuesta inflamatoria, la secreción de insulina, la regulación del tono vascular y la percepción del dolor. En la presente revisión se describen las características estructurales y farmacológicas de los receptores purinérgicos y se analiza la interacción dinámica entre estos receptores, los nucleósidos y nucleótidos, y las ectonucleotidasas, con especial atención a la dinámica de la agregación plaquetaria, la respuesta inmune y la hidratación de las mucosas respiratorias.In the last decade evidence accumulated that nucleosides and nucleotides of both uridine and adenine can act as extracellular signaling factors. Their action is mediated by two main types of surface receptors commonly known as purinergic. P1 receptors are metabotropic and activated by adenosine, whereas receptors for nucleotides (ATP, ADP, UTP and UDP and nucleotide-sugars (UDP-glucose and UDP-galactose can be either metabotropic (P2Y or ionotropic (P2X. The importance and complexity of this signaling system

  16. The guanine nucleotide exchange factor RIC8 regulates conidial germination through Gα proteins in Neurospora crassa.

    Directory of Open Access Journals (Sweden)

    Carla J Eaton

    Full Text Available Heterotrimeric G protein signaling is essential for normal hyphal growth in the filamentous fungus Neurospora crassa. We have previously demonstrated that the non-receptor guanine nucleotide exchange factor RIC8 acts upstream of the Gα proteins GNA-1 and GNA-3 to regulate hyphal extension. Here we demonstrate that regulation of hyphal extension results at least in part, from an important role in control of asexual spore (conidia germination. Loss of GNA-3 leads to a drastic reduction in conidial germination, which is exacerbated in the absence of GNA-1. Mutation of RIC8 leads to a reduction in germination similar to that in the Δgna-1, Δgna-3 double mutant, suggesting that RIC8 regulates conidial germination through both GNA-1 and GNA-3. Support for a more significant role for GNA-3 is indicated by the observation that expression of a GTPase-deficient, constitutively active gna-3 allele in the Δric8 mutant leads to a significant increase in conidial germination. Localization of the three Gα proteins during conidial germination was probed through analysis of cells expressing fluorescently tagged proteins. Functional TagRFP fusions of each of the three Gα subunits were constructed through insertion of TagRFP in a conserved loop region of the Gα subunits. The results demonstrated that GNA-1 localizes to the plasma membrane and vacuoles, and also to septa throughout conidial germination. GNA-2 and GNA-3 localize to both the plasma membrane and vacuoles during early germination, but are then found in intracellular vacuoles later during hyphal outgrowth.

  17. Molecular analysis of "de novo" purine biosynthesis in solanaceous species and in Arabidopsis thaliana

    DEFF Research Database (Denmark)

    van der Graaff, Eric; Hooykaas, Paul; Lein, Wolfgang

    2004-01-01

    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...... biosynthesis pathway in plants, and the in planta functional analysis of PRPP (5-phosphoribosyl-1-pyrophoshate) amidotransferase (ATase), catalyzing the first committed step of the "de novo" purine biosynthesis. The cloning of the genes involved in the purine biosynthesis pathway was attained by a screening...... strategy with heterologous cDNA probes and by using S. cerevisiae mutants for complementation. Southern hybridization showed a complex genomic organization for these genes in solanaceous species and their organ- and developmental specific expression was analyzed by Northern hybridization. The specific role...

  18. Simultaneous quantification by HPLC of purines in umami soup stock and evaluation of their effects on extracellular and intracellular purine metabolism.

    Science.gov (United States)

    Fukuuchi, T; Iyama, N; Yamaoka, N; Kaneko, K

    2018-04-13

    Ribonucleotide flavor enhancers such as inosine monophosphate (IMP) and guanosine monophosphate (GMP) provide umami taste, similarly to glutamine. Japanese cuisine frequently uses soup stocks containing these nucleotides to enhance umami. We quantified 18 types of purines (nucleotides, nucleosides, and purine bases) in three soup stocks (chicken, consommé, and dried bonito soup). IMP was the most abundant purine in all umami soup stocks, followed by hypoxanthine, inosine, and GMP. The IMP content of dried bonito soup was the highest of the three soup stocks. We also evaluated the effects of these purines on extracellular and intracellular purine metabolism in HepG2 cells after adding each umami soup stock to the cells. An increase in inosine and hypoxanthine was evident 1 h and 4 h after soup stock addition, and a low amount of xanthine and guanosine was observed in the extracellular medium. The addition of chicken soup stock resulted in increased intracellular and extracellular levels of uric acid and guanosine. Purine metabolism may be affected by ingredients present in soups.

  19. Proteomic analysis of Rac1 signaling regulation by guanine nucleotide exchange factors.

    Science.gov (United States)

    Marei, Hadir; Carpy, Alejandro; Macek, Boris; Malliri, Angeliki

    2016-08-02

    The small GTPase Rac1 is implicated in various cellular processes that are essential for normal cell function. Deregulation of Rac1 signaling has also been linked to a number of diseases, including cancer. The diversity of Rac1 functioning in cells is mainly attributed to its ability to bind to a multitude of downstream effectors following activation by Guanine nucleotide Exchange Factors (GEFs). Despite the identification of a large number of Rac1 binding partners, factors influencing downstream specificity are poorly defined, thus hindering the detailed understanding of both Rac1's normal and pathological functions. In a recent study, we demonstrated a role for 2 Rac-specific GEFs, Tiam1 and P-Rex1, in mediating Rac1 anti- versus pro-migratory effects, respectively. Importantly, via conducting a quantitative proteomic screen, we identified distinct changes in the Rac1 interactome following activation by either GEF, indicating that these opposing effects are mediated through GEF modulation of the Rac1 interactome. Here, we present the full list of identified Rac1 interactors together with functional annotation of the differentially regulated Rac1 binding partners. In light of this data, we also provide additional insights into known and novel signaling cascades that might account for the GEF-mediated Rac1-driven cellular effects.

  20. Structural basis for solute transport, nucleotide regulation, and immunological recognition of Neisseria meningitidis PorB

    Energy Technology Data Exchange (ETDEWEB)

    Tanabe, Mikio; Nimigean, Crina M.; Iverson, T.M. (Weill-Med); (Vanderbilt)

    2010-06-25

    PorB is the second most prevalent outer membrane protein in Neisseria meningitidis. PorB is required for neisserial pathogenesis and can elicit a Toll-like receptor mediated host immune response. Here, the x-ray crystal structure of PorB has been determined to 2.3 {angstrom} resolution. Structural analysis and cocrystallization studies identify three putative solute translocation pathways through the channel pore: One pathway transports anions nonselectively, one transports cations nonselectively, and one facilitates the specific uptake of sugars. During infection, PorB likely binds host mitochondrial ATP, and cocrystallization with the ATP analog AMP-PNP suggests that binding of nucleotides regulates these translocation pathways both by partial occlusion of the pore and by restricting the motion of a putative voltage gating loop. PorB is located on the surface of N. meningitidis and can be recognized by receptors of the host innate immune system. Features of PorB suggest that Toll-like receptor mediated recognition outer membrane proteins may be initiated with a nonspecific electrostatic attraction.

  1. Guanine nucleotide binding to the Bateman domain mediates the allosteric inhibition of eukaryotic IMP dehydrogenases

    Science.gov (United States)

    Buey, Rubén M.; Ledesma-Amaro, Rodrigo; Velázquez-Campoy, Adrián; Balsera, Mónica; Chagoyen, Mónica; de Pereda, José M.; Revuelta, José L.

    2015-11-01

    Inosine-5'-monophosphate dehydrogenase (IMPDH) plays key roles in purine nucleotide metabolism and cell proliferation. Although IMPDH is a widely studied therapeutic target, there is limited information about its physiological regulation. Using Ashbya gossypii as a model, we describe the molecular mechanism and the structural basis for the allosteric regulation of IMPDH by guanine nucleotides. We report that GTP and GDP bind to the regulatory Bateman domain, inducing octamers with compromised catalytic activity. Our data suggest that eukaryotic and prokaryotic IMPDHs might have developed different regulatory mechanisms, with GTP/GDP inhibiting only eukaryotic IMPDHs. Interestingly, mutations associated with human retinopathies map into the guanine nucleotide-binding sites including a previously undescribed non-canonical site and disrupt allosteric inhibition. Together, our results shed light on the mechanisms of the allosteric regulation of enzymes mediated by Bateman domains and provide a molecular basis for certain retinopathies, opening the door to new therapeutic approaches.

  2. Regulation of mitotic spindle formation by the RhoA guanine nucleotide exchange factor ARHGEF10

    Directory of Open Access Journals (Sweden)

    Satoh Takaya

    2009-07-01

    Full Text Available Abstract Background The Dbl family guanine nucleotide exchange factor ARHGEF10 was originally identified as the product of the gene associated with slowed nerve-conduction velocities of peripheral nerves. However, the function of ARHGEF10 in mammalian cells is totally unknown at a molecular level. ARHGEF10 contains no distinctive functional domains except for tandem Dbl homology-pleckstrin homology and putative transmembrane domains. Results Here we show that RhoA is a substrate for ARHGEF10. In both G1/S and M phases, ARHGEF10 was localized in the centrosome in adenocarcinoma HeLa cells. Furthermore, RNA interference-based knockdown of ARHGEF10 resulted in multipolar spindle formation in M phase. Each spindle pole seems to contain a centrosome consisting of two centrioles and the pericentriolar material. Downregulation of RhoA elicited similar phenotypes, and aberrant mitotic spindle formation following ARHGEF10 knockdown was rescued by ectopic expression of constitutively activated RhoA. Multinucleated cells were not increased upon ARHGEF10 knockdown in contrast to treatment with Y-27632, a specific pharmacological inhibitor for the RhoA effector kinase ROCK, which induced not only multipolar spindle formation, but also multinucleation. Therefore, unregulated centrosome duplication rather than aberration in cytokinesis may be responsible for ARHGEF10 knockdown-dependent multipolar spindle formation. We further isolated the kinesin-like motor protein KIF3B as a binding partner of ARHGEF10. Knockdown of KIF3B again caused multipolar spindle phenotypes. The supernumerary centrosome phenotype was also observed in S phase-arrested osteosarcoma U2OS cells when the expression of ARHGEF10, RhoA or KIF3B was abrogated by RNA interference. Conclusion Collectively, our results suggest that a novel RhoA-dependent signaling pathway under the control of ARHGEF10 has a pivotal role in the regulation of the cell division cycle. This pathway is not involved in

  3. Tye7 regulates yeast Ty1 retrotransposon sense and antisense transcription in response to adenylic nucleotides stress.

    Science.gov (United States)

    Servant, Géraldine; Pinson, Benoit; Tchalikian-Cosson, Aurélie; Coulpier, Fanny; Lemoine, Sophie; Pennetier, Carole; Bridier-Nahmias, Antoine; Todeschini, Anne Laure; Fayol, Hélène; Daignan-Fornier, Bertrand; Lesage, Pascale

    2012-07-01

    Transposable elements play a fundamental role in genome evolution. It is proposed that their mobility, activated under stress, induces mutations that could confer advantages to the host organism. Transcription of the Ty1 LTR-retrotransposon of Saccharomyces cerevisiae is activated in response to a severe deficiency in adenylic nucleotides. Here, we show that Ty2 and Ty3 are also stimulated under these stress conditions, revealing the simultaneous activation of three active Ty retrotransposon families. We demonstrate that Ty1 activation in response to adenylic nucleotide depletion requires the DNA-binding transcription factor Tye7. Ty1 is transcribed in both sense and antisense directions. We identify three Tye7 potential binding sites in the region of Ty1 DNA sequence where antisense transcription starts. We show that Tye7 binds to Ty1 DNA and regulates Ty1 antisense transcription. Altogether, our data suggest that, in response to adenylic nucleotide reduction, TYE7 is induced and activates Ty1 mRNA transcription, possibly by controlling Ty1 antisense transcription. We also provide the first evidence that Ty1 antisense transcription can be regulated by environmental stress conditions, pointing to a new level of control of Ty1 activity by stress, as Ty1 antisense RNAs play an important role in regulating Ty1 mobility at both the transcriptional and post-transcriptional stages.

  4. Pyridine nucleotides in regulation of cell death and survival by redox and non-redox reactions.

    Science.gov (United States)

    Novak Kujundžić, Renata; Žarković, Neven; Gall Trošelj, Koraljka

    2014-01-01

    Changes of the level and ratios of pyridine nucleotides determine metabolism- dependent cellular redox status and the activity of poly(ADP-ribose) polymerases (PARPs) and sirtuins, thereby influencing several processes closely related to cell survival and death. Pyridine nucleotides participate in numerous metabolic reactions whereby their net cellular level remains constant, but the ratios of NAD+/NADP+ and NADH/NADPH oscillate according to metabolic changes in response to diverse stress signals. In non-redox reactions, NAD+ is degraded and quickly, afterward, resynthesized in the NAD+ salvage pathway, unless overwhelming activation of PARP-1 consumes NAD+ to the point of no return, when the cell can no longer generate enough ATP to accommodate NAD+ resynthesis. The activity of PARP-1 is mandatory for the onset of cytoprotective autophagy on sublethal stress signals. It has become increasingly clear that redox status, largely influenced by the metabolism-dependent composition of the pyridine nucleotides pool, plays an important role in the synthesis of pro-apoptotic and anti-apoptotic sphingolipids. Awareness of the involvement of the prosurvival sphingolipid, sphingosine-1-phosphate, in transition from inflammation to malignant transformation has recently emerged. Here, the participation of pyridine nucleotides in redox and non-redox reactions, sphingolipid metabolism, and their role in cell fate decisions is reviewed.

  5. A Bifunctional Intronic Element Regulates the Expression of the Arginine/Lysine Transporter Cat-1 via Mechanisms Involving the Purine-rich Element Binding Protein A (Purα)*

    Science.gov (United States)

    Huang, Charlie C.; Chiribau, Calin-Bogdan; Majumder, Mithu; Chiang, Cheng-Ming; Wek, Ronald C.; Kelm, Robert J.; Khalili, Kamel; Snider, Martin D.; Hatzoglou, Maria

    2009-01-01

    Expression of the arginine/lysine transporter Cat-1 is highly induced in proliferating and stressed cells via mechanisms that include transcriptional activation. A bifunctional INE (intronic element) within the first intron of the Cat-1 gene was identified and characterized in this study. The INE had high sequence homology to an amino acid response element and was shown to act as a transcriptional enhancer in unstressed cells by binding the transcription factor, purine-rich element binding protein A (Purα). During endoplasmic reticulum stress, binding of Purα to the INE decreased; the element acted as a positive regulator in early stress by binding of the transcription factor ATF4 and as a negative regulator in prolonged stress by binding the stress-induced C/EBP family member, CHOP. We conclude that transcriptional control of the Cat-1 gene is tightly controlled by multiple cis-DNA elements, contributing to regulation of cationic amino acid transport for cell growth and proliferation. In addition, we propose that genes may use stress-response elements such as the INE to support basal expression in the absence of stress. PMID:19720825

  6. Noninvasive microelectrode ion flux estimation technique (MIFE) for the study of the regulation of root membrane transport by cyclic nucleotides

    KAUST Repository

    Ordoñ ez, Natalia Maria; Shabala, Lana; Gehring, Christoph A; Shabala, Sergey Nikolayevich

    2013-01-01

    Changes in ion permeability and subsequently intracellular ion concentrations play a crucial role in intracellular and intercellular communication and, as such, confer a broad array of developmental and adaptive responses in plants. These changes are mediated by the activity of plasma-membrane based transport proteins many of which are controlled by cyclic nucleotides and/or other signaling molecules. The MIFE technique for noninvasive microelectrode ion flux measuring allows concurrent quantification of net fluxes of several ions with high spatial (μm range) and temporal (ca. 5 s) resolution, making it a powerful tool to study various aspects of downstream signaling events in plant cells. This chapter details basic protocols enabling the application of the MIFE technique to study regulation of root membrane transport in general and cyclic nucleotide mediated transport in particular. © Springer Science+Business Media New York 2013.

  7. Noninvasive microelectrode ion flux estimation technique (MIFE) for the study of the regulation of root membrane transport by cyclic nucleotides

    KAUST Repository

    Ordoñez, Natalia Maria

    2013-09-03

    Changes in ion permeability and subsequently intracellular ion concentrations play a crucial role in intracellular and intercellular communication and, as such, confer a broad array of developmental and adaptive responses in plants. These changes are mediated by the activity of plasma-membrane based transport proteins many of which are controlled by cyclic nucleotides and/or other signaling molecules. The MIFE technique for noninvasive microelectrode ion flux measuring allows concurrent quantification of net fluxes of several ions with high spatial (μm range) and temporal (ca. 5 s) resolution, making it a powerful tool to study various aspects of downstream signaling events in plant cells. This chapter details basic protocols enabling the application of the MIFE technique to study regulation of root membrane transport in general and cyclic nucleotide mediated transport in particular. © Springer Science+Business Media New York 2013.

  8. Purine content of some Philippine foods

    International Nuclear Information System (INIS)

    Lontoc, A.V.; Ladines, E.O.; Jalandoon, S.A.

    1993-01-01

    To facilitate dietary advice for prevention and management of hyperuricemia, the content of individual purines, namely: adenine, hypoxanthine, guanine and xanthine was determined in market samples of 161 legumes and dried beans, 41 organ meats, and 25 finfishes and shellfishes using Waters HPLC Model ALC/GPC 244. Analysis for moisture, protein and purines were conducted on the slurries or dried forms of the edible portions of the food samples. Food samples were subsequently classified into three categories adapted from Williams' dietary guide for purines, expressed in decreasing levels of total purines per 100 g serving. Category 1 foods are those that contain very large amount (150 to 1000 mg) of total purines; category 2 foods are those that contain a large amount (75-<150 mg) of total purines; and category 3 foods are those that contain a moderate amount (up to 75 mg) of total purines. (auth.). 17 refs.; 8 tabs

  9. A Steric-inhibition model for regulation of nucleotide exchange via the Dock180 family of GEFs.

    Science.gov (United States)

    Lu, Mingjian; Kinchen, Jason M; Rossman, Kent L; Grimsley, Cynthia; Hall, Matthew; Sondek, John; Hengartner, Michael O; Yajnik, Vijay; Ravichandran, Kodi S

    2005-02-22

    CDM (CED-5, Dock180, Myoblast city) family members have been recently identified as novel, evolutionarily conserved guanine nucleotide exchange factors (GEFs) for Rho-family GTPases . They regulate multiple processes, including embryonic development, cell migration, apoptotic-cell engulfment, tumor invasion, and HIV-1 infection, in diverse model systems . However, the mechanism(s) of regulation of CDM proteins has not been well understood. Here, our studies on the prototype member Dock180 reveal a steric-inhibition model for regulating the Dock180 family of GEFs. At basal state, the N-terminal SH3 domain of Dock180 binds to the distant catalytic Docker domain and negatively regulates the function of Dock180. Further studies revealed that the SH3:Docker interaction sterically blocks Rac access to the Docker domain. Interestingly, ELMO binding to the SH3 domain of Dock180 disrupted the SH3:Docker interaction, facilitated Rac access to the Docker domain, and contributed to the GEF activity of the Dock180/ELMO complex. Additional genetic rescue studies in C. elegans suggested that the regulation of the Docker-domain-mediated GEF activity by the SH3 domain and its adjoining region is evolutionarily conserved. This steric-inhibition model may be a general mechanism for regulating multiple SH3-domain-containing Dock180 family members and may have implications for a variety of biological processes.

  10. Isotopically labelled pyrimidines and purines

    International Nuclear Information System (INIS)

    Balaban, A.T.; Bally, I.

    1987-01-01

    Among the three diazines, pyrimidine is by far the most important one because its derivatives uracil, thymine and cytosine are constituents of the ubiquitous deoxynucleic acids (DNA) and ribonucleic acids (RNA). Other derivatives of pyrimidine without condensed rings include barbiturates, alloxan, orotic acid and thiamine or vitamin B 1 . From the polycyclic derivatives of pyrimidine such as pteridine, alloxazine, and purine, the latter, through its derivatives adenine and guanine complete the list of bases which occur in DNA and RNA: in addition, other purine derivatives such as hypoxanthine, xanthine, theobromine, theophylline, caffeine and uric acid are important natural products with biological activity. The paper presents methods for preparing isotopically labeled pyrimidines as well as purine derivatives. For convenience, the authors describe separately carbon-labeled with radioisotopes 11 C (T 1/2 = 20.3 min) and 14 C (T 1/2 = 5736 years) or the stable isotope 13 C (natural abundance 1.1%) and then hydrogen-labeled systems with the radioisotope 3 H ≡ T (T 1/2 = 12.346 years) or with the stable isotope 2 H ≡ D (natural abundance 0.015%). We do not separate stable from radioactive isotopes because the synthetic methods are identical for the same element; however, the introduction of hydrogen isotopes into organic molecules is often performed by reactions such as isotope exchange which cannot take place in the case of carbon isotopes

  11. Differential Rac1 signalling by guanine nucleotide exchange factors implicates FLII in regulating Rac1-driven cell migration

    Science.gov (United States)

    Marei, Hadir; Carpy, Alejandro; Woroniuk, Anna; Vennin, Claire; White, Gavin; Timpson, Paul; Macek, Boris; Malliri, Angeliki

    2016-01-01

    The small GTPase Rac1 has been implicated in the formation and dissemination of tumours. Upon activation by guanine nucleotide exchange factors (GEFs), Rac1 associates with a variety of proteins in the cell thereby regulating various functions, including cell migration. However, activation of Rac1 can lead to opposing migratory phenotypes raising the possibility of exacerbating tumour progression when targeting Rac1 in a clinical setting. This calls for the identification of factors that influence Rac1-driven cell motility. Here we show that Tiam1 and P-Rex1, two Rac GEFs, promote Rac1 anti- and pro-migratory signalling cascades, respectively, through regulating the Rac1 interactome. In particular, we demonstrate that P-Rex1 stimulates migration through enhancing the interaction between Rac1 and the actin-remodelling protein flightless-1 homologue, to modulate cell contraction in a RhoA-ROCK-independent manner. PMID:26887924

  12. Purines and Carotid Body: New Roles in Pathological Conditions

    Directory of Open Access Journals (Sweden)

    Silvia V. Conde

    2017-12-01

    Full Text Available It is known that adenosine and adenosine-5′-triphosphate (ATP are excitatory mediators involved in carotid body (CB hypoxic signaling. The CBs are peripheral chemoreceptors classically defined by O2, CO2, and pH sensors. When hypoxia activates the CB, it induces the release of neurotransmitters from chemoreceptor cells leading to an increase in the action potentials frequency at the carotid sinus nerve (CSN. This increase in the firing frequency of the CSN is integrated in the brainstem to induce cardiorespiratory compensatory responses. In the last decade several pathologies, as, hypertension, diabetes, obstructive sleep apnea and heart failure have been associated with CB overactivation. In the first section of the present manuscript we review in a concise manner fundamental aspects of purine metabolism. The second section is devoted to the role of purines on the hypoxic response of the CB, providing the state-of-the art for the presence of adenosine and ATP receptors in the CB; for the role of purines at presynaptic level in CB chemoreceptor cells, as well as, its metabolism and regulation; at postsynaptic level in the CSN activity; and on the ventilatory responses to hypoxia. Recently, we have showed that adenosine is involved in CB hypersensitization during chronic intermittent hypoxia (CIH, which mimics obstructive sleep apnea, since caffeine, a non-selective adenosine receptor antagonist that inhibits A2A and A2B adenosine receptors, decreased CSN chemosensory activity in animals subjected to CIH. Apart from this involvement of adenosine in CB sensitization in sleep apnea, it was recently found that P2X3 ATP receptor in the CB contributes to increased chemoreflex hypersensitivity and hypertension in spontaneously hypertension rats. Therefore the last section of this manuscript is devoted to review the recent findings on the role of purines in CB-mediated pathologies as hypertension, diabetes and sleep apnea emphasizing the potential

  13. Guanine nucleotide-binding protein regulation of melatonin receptors in lizard brain

    International Nuclear Information System (INIS)

    Rivkees, S.A.; Carlson, L.L.; Reppert, S.M.

    1989-01-01

    Melatonin receptors were identified and characterized in crude membrane preparations from lizard brain by using 125 I-labeled melatonin ( 125 I-Mel), a potent melatonin agonist. 125 I-Mel binding sites were saturable; Scatchard analysis revealed high-affinity and lower affinity binding sites, with apparent K d of 2.3 ± 1.0 x 10 -11 M and 2.06 ± 0.43 x 10 -10 M, respectively. Binding was reversible and inhibited by melatonin and closely related analogs but not by serotonin or norepinephrine. Treatment of crude membranes with the nonhydrolyzable GTP analog guanosine 5'-[γ-thio]triphosphate (GTP[γS]), significantly reduced the number of high-affinity receptors and increased the dissociation rate of 125 I-Mel from its receptor. Furthermore, GTP[γS] treatment of ligand-receptor complexes solubilized by Triton X-100 also led to a rapid dissociation of 125 I-Mel from solubilized ligand-receptor complexes. Gel filtration chromatography of solubilized ligand-receptor complexes revealed two major peaks of radioactivity corresponding to M r > 400,000 and M r ca. 110,000. This elution profile was markedly altered by pretreatment with GTP[γS] before solubilization; only the M r 110,000 peak was present in GTP[γS]-pretreated membranes. The results strongly suggest that 125 I-mel binding sites in lizard brain are melatonin receptors, with agonist-promoted guanine nucleotide-binding protein (G protein) coupling and that the apparent molecular size of receptors uncoupled from G proteins is about 110,000

  14. Effects of caffeine on purine metabolism and ultraviolet light-induced lethality in cultured mammalian cells

    International Nuclear Information System (INIS)

    Waldren, C.A.; Patterson, D.

    1979-01-01

    Caffeine, at doses which enhance the killing action of ultraviolet light, inhibits both de novo synthesis and the utilization of exogenous purines in cultured CHO-K1, a Chinese hamster ovary cell line. The effect is dose dependent, with a caffeine concentration of 7.5 mM producing a 90% reduction in 15 min. Interference with utilization of exogenous purines was seen as a substantial decrease in the conversion of [14C]hypoxanthine, [14C]adenine, or [14C]guanine into their respective di- and triphosphates in the presence of caffeine. Thus, one of the ways by which antimetabolites and caffeine act to enhance ultraviolet light killing may be by interference with the supply of purine nucleotides needed for repair

  15. Three-dimensional structure of E. Coli purine nucleoside phosphorylase at 0.99 Å resolution

    Energy Technology Data Exchange (ETDEWEB)

    Timofeev, V. I., E-mail: tostars@mail.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Abramchik, Yu. A., E-mail: ugama@yandex.ru [Russian Academy of Sciences, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry (Russian Federation); Zhukhlistova, N. E., E-mail: inna@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Muravieva, T. I.; Esipov, R. S. [Russian Academy of Sciences, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry (Russian Federation); Kuranova, I. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2016-03-15

    Purine nucleoside phosphorylases (PNPs) catalyze the reversible phosphorolysis of nucleosides and are key enzymes involved in nucleotide metabolism. They are essential for normal cell function and can catalyze the transglycosylation. Crystals of E. coli PNP were grown in microgravity by the capillary counterdiffusion method through a gel layer. The three-dimensional structure of the enzyme was determined by the molecular-replacement method at 0.99 Å resolution. The structural features are considered, and the structure of E. coli PNP is compared with the structures of the free enzyme and its complexes with purine base derivatives established earlier. A comparison of the environment of the purine base in the complex of PNP with formycin A and of the pyrimidine base in the complex of uridine phosphorylase with thymidine revealed the main structural features of the base-binding sites. Coordinates of the atomic model determined with high accuracy were deposited in the Protein Data Bank (PDB-ID: 4RJ2).

  16. Single Nucleotide Polymorphisms Can Create Alternative Polyadenylation Signals and Affect Gene Expression through Loss of MicroRNA-Regulation

    Science.gov (United States)

    Thomas, Laurent F.; Sætrom, Pål

    2012-01-01

    Alternative polyadenylation (APA) can for example occur when a protein-coding gene has several polyadenylation (polyA) signals in its last exon, resulting in messenger RNAs (mRNAs) with different 3′ untranslated region (UTR) lengths. Different 3′UTR lengths can give different microRNA (miRNA) regulation such that shortened transcripts have increased expression. The APA process is part of human cells' natural regulatory processes, but APA also seems to play an important role in many human diseases. Although altered APA in disease can have many causes, we reasoned that mutations in DNA elements that are important for the polyA process, such as the polyA signal and the downstream GU-rich region, can be one important mechanism. To test this hypothesis, we identified single nucleotide polymorphisms (SNPs) that can create or disrupt APA signals (APA-SNPs). By using a data-integrative approach, we show that APA-SNPs can affect 3′UTR length, miRNA regulation, and mRNA expression—both between homozygote individuals and within heterozygote individuals. Furthermore, we show that a significant fraction of the alleles that cause APA are strongly and positively linked with alleles found by genome-wide studies to be associated with disease. Our results confirm that APA-SNPs can give altered gene regulation and that APA alleles that give shortened transcripts and increased gene expression can be important hereditary causes for disease. PMID:22915998

  17. Callus induction of leaf explant Piper betle L. Var Nigra with combination of plant growth regulators indole-3-acetic acid (IAA), benzyl amino purin (BAP) and kinetin

    Science.gov (United States)

    Junairiah, Zuraidassanaaz, Nabilah Istighfari; Izdihar, Fairuz Nabil; Manuhara, Yosephine Sri Wulan

    2017-09-01

    The purpose of this research was to determine the combination of plant growth regulators IAA, BAP and kinetin towards callus induction and growth of leaf explants Piper betle L. VarNigra. Explants from leaf of Piper betle L. VarNigra was cultured on MS medium with 24 treatment combinations of plant growth regulators IAA and BAP and 24 treatment combinations of plant growth regulators IAA and kinetin with 0.0;0.5;1.0;1.5;2.0 mg/L concentration respectively, the observed variable were the length of time the formation of callus, callus morphology, fresh and dry weight of callus. The results of this research showed that the combination of growth regulators IAA with BAP and kinetin had effects on leaf growth of Piper betle L. VarNigra. During 8 weeks observation, it indicated that the combination of concentration IAA 0.5 mg/L and BAP 2.0 mg/L showed fastest callus formation at 8.5 days. Combination of concentration IAA 1.0 mg/L and BAP 1.5 mg/L showed the highest of fresh weight at 0.6596 grams, and the highest dry weight was obtained from the combination of concentration IAA 0.5 mg/L and BAP 0.5 mg/L at 0.0727 grams. Combination of concentration IAA 1.0 mg/L and kinetin 1.5 mg/L had the highest of fresh weight at 0.2972 grams and the highest dry weight at 0.1660 grams. Callus of Piper betle L. VarNigra had two textures, that were compact and friable, and also showed various kind of colors, like white, greenish white, yellowish white, tanned white, brown and black. Based on this research, that concentration IAA 1.0 mg/L and 1.5 mg/L kinetin was the best combination for induction of callus from leaf of Piper betle L. Var Nigra.

  18. Nucleotide synthesis is regulated by cytoophidium formation during neurodevelopment and adaptive metabolism

    Directory of Open Access Journals (Sweden)

    Gabriel N. Aughey

    2014-10-01

    Full Text Available The essential metabolic enzyme CTP synthase (CTPsyn can be compartmentalised to form an evolutionarily-conserved intracellular structure termed the cytoophidium. Recently, it has been demonstrated that the enzymatic activity of CTPsyn is attenuated by incorporation into cytoophidia in bacteria and yeast cells. Here we demonstrate that CTPsyn is regulated in a similar manner in Drosophila tissues in vivo. We show that cytoophidium formation occurs during nutrient deprivation in cultured cells, as well as in quiescent and starved neuroblasts of the Drosophila larval central nervous system. We also show that cytoophidia formation is reversible during neurogenesis, indicating that filament formation regulates pyrimidine synthesis in a normal developmental context. Furthermore, our global metabolic profiling demonstrates that CTPsyn overexpression does not significantly alter CTPsyn-related enzymatic activity, suggesting that cytoophidium formation facilitates metabolic stabilisation. In addition, we show that overexpression of CTPsyn only results in moderate increase of CTP pool in human stable cell lines. Together, our study provides experimental evidence, and a mathematical model, for the hypothesis that inactive CTPsyn is incorporated into cytoophidia.

  19. The immediate nucleotide precursor, guanosine triphosphate, in the riboflavin biosynthetic pathway

    International Nuclear Information System (INIS)

    Mitsuda, Hisateru; Nakajima, Kenji; Nadamoto, Tomonori

    1977-01-01

    In the present paper, the nucleotide precursor of riboflavin was investigated by experiments with labeled purines using non-growing cells of Eremothecium ashbyii. The added purines, at 10 -4 M, were effectively incorporated into riboflavin at an early stage of riboflavin biosynthesis under the experimental conditions. In particular, both labeled xanthine and labeled guanine were specifically transported to guanosine nucleotides, GMP, GDP, GDP-Mannose and GTP, in the course of the riboflavin biosynthesis. A comparison of specific activities of labeled guanosine nucleotides and labeled riboflavin indicated that the nucleotide precursor of riboflavin is guanosine triphosphate. From the results obtained, a biosynthetic pathway of riboflavin is proposed. (auth.)

  20. Preliminary crystallographic studies of purine nucleoside phosphorylase from the cariogenic pathogen Streptococcus mutans

    International Nuclear Information System (INIS)

    Hou, Qiao-Ming; Liu, Xiang; Brostromer, Erik; Li, Lan-Fen; Su, Xiao-Dong

    2009-01-01

    Purine nucleoside phosphorylase (PNP), which is a pivotal enzyme in the nucleotide-salvage pathway, has been expressed in Escherichia coli strain BL21 (DE3) in a soluble form at a high level. After purification of the PNP enzyme, the protein was crystallized using the sitting-drop vapour-diffusion technique. The punA gene of the cariogenic pathogen Streptococcus mutans encodes purine nucleoside phosphorylase (PNP), which is a pivotal enzyme in the nucleotide-salvage pathway, catalyzing the phosphorolysis of purine nucleosides to generate purine bases and α-ribose 1-phosphate. In the present work, the PNP protein was expressed in Escherichia coli strain BL21 (DE3) in a soluble form at a high level. After purification of the PNP enzyme, the protein was crystallized using the sitting-drop vapour-diffusion technique; the crystals diffracted to 1.6 Å resolution at best. The crystals belonged to space group H3, with unit-cell parameters a = b = 113.0, c = 60.1 Å

  1. Differential regulation of inositol 1,4,5-trisphosphate by co-existing P2Y-purinoceptors and nucleotide receptors on bovine aortic endothelial cells.

    Science.gov (United States)

    Purkiss, J R; Wilkinson, G F; Boarder, M R

    1994-03-01

    1. We have examined the inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) responses in bovine aortic endothelial (BAE) cells to purines (ATP, ADP and analogues) and the pyrimidine, uridine triphosphate (UTP). 2. Exchange of medium on BAE cells in the absence of agonist was found to be a stimulus for Ins(1,4,5)P3 generation. BAE cells stimulated with 100 microM ATP, 30 microM 2MeSATP (an agonist at P2Y-purinoceptors but not nucleotide receptors) or 100 microM UTP (an agonist at nucleotide receptors but not P2Y-purinoceptors) gave Ins(1,4,5)P3 responses above that caused by exchange of medium. The time course was rapid, with peak response within the first 5 s and levels returning close to basal after 30 s of stimulation. 3. Significant differences in Ins(1,4,5)P3 responses to 100 microM UTP and 30 microM 2MeSATP stimulation were observed. The response to UTP was reproducibly more sustained than that to 2MeSATP. 4. Stimulation of BAE cells with 100 microM UTP plus 30 microM 2MeSATP produced a response statistically indistinguishable from that predicted by addition of the responses to the two agonists in isolation. 5. The Ins(1,4,5)P3 response to UTP was attenuated to 25% of control by pretreatment of BAE cells with pertussis toxin. Responses to 2MeSATP and ADP were essentially unaffected. ATP stimulation was reduced to 65% of control. 6. Activation of protein kinase C with tetradecanoyl phorbol acetate (TPA) profoundly inhibited Ins(1,4,5)P3 responses to 2MeSATP and ADP but had no effect on UTP stimulation. The protein kinase C inhibitor, Ro 31-8220, enhanced responses to 2MeSATP, ADP and ATP but no effect was observed on UTP stimulation. 7. These observations show that nucleotide and P2Y-receptors mobilise the second messenger Ins(1,4,5)P3 by separate routes resulting in different patterns of generation and suggest that while ATP activates both receptors, ADP principally influences these cells by interacting with the P2Y-purinoceptors.

  2. Nucleotide Metabolism

    DEFF Research Database (Denmark)

    Martinussen, Jan; Willemoës, M.; Kilstrup, Mogens

    2011-01-01

    Metabolic pathways are connected through their utilization of nucleotides as supplier of energy, allosteric effectors, and their role in activation of intermediates. Therefore, any attempt to exploit a given living organism in a biotechnological process will have an impact on nucleotide metabolis...

  3. Different characteristics and nucleotide binding properties of inosine monophosphate dehydrogenase (IMPDH isoforms.

    Directory of Open Access Journals (Sweden)

    Elaine C Thomas

    Full Text Available We recently reported that Inosine Monophosphate Dehydrogenase (IMPDH, a rate-limiting enzyme in de novo guanine nucleotide biosynthesis, clustered into macrostructures in response to decreased nucleotide levels and that there were differences between the IMPDH isoforms, IMPDH1 and IMPDH2. We hypothesised that the Bateman domains, which are present in both isoforms and serve as energy-sensing/allosteric modules in unrelated proteins, would contribute to isoform-specific differences and that mutations situated in and around this domain in IMPDH1 which give rise to retinitis pigmentosa (RP would compromise regulation. We employed immuno-electron microscopy to investigate the ultrastructure of IMPDH macrostructures and live-cell imaging to follow clustering of an IMPDH2-GFP chimera in real-time. Using a series of IMPDH1/IMPDH2 chimera we demonstrated that the propensity to cluster was conferred by the N-terminal 244 amino acids, which includes the Bateman domain. A protease protection assay suggested isoform-specific purine nucleotide binding characteristics, with ATP protecting IMPDH1 and AMP protecting IMPDH2, via a mechanism involving conformational changes upon nucleotide binding to the Bateman domain without affecting IMPDH catalytic activity. ATP binding to IMPDH1 was confirmed in a nucleotide binding assay. The RP-causing mutation, R224P, abolished ATP binding and nucleotide protection and this correlated with an altered propensity to cluster. Collectively these data demonstrate that (i the isoforms are differentially regulated by AMP and ATP by a mechanism involving the Bateman domain, (ii communication occurs between the Bateman and catalytic domains and (iii the RP-causing mutations compromise such regulation. These findings support the idea that the IMPDH isoforms are subject to distinct regulation and that regulatory defects contribute to human disease.

  4. Guanine nucleotide regulation of muscarinic receptor-mediated inositol phosphate formation in permeabilized 1321N1 cells

    International Nuclear Information System (INIS)

    Orellana, S.A.; Trilivas, I.; Brown, J.H.

    1986-01-01

    Carbachol and guanine nucleotides stimulate formation of the ( 3 H)inositol phosphates IP, IP2, and IP3 in saponin-permeabilized monolayers labelled with ( 3 H) inositol. Carbachol alone has little effect on formation of the ( 3 H) inositol phosphates (IPs), but GTPγS causes synergistic accumulation of ( 3 H)IPs to levels similar to those seen in intact cells. GTP, GppNHp, and GTPγS all support formation of the ( 3 H)IPs, with or without hormone, but GTPγS is the most effective. In the presence of GTPγS, the effect of carbachol is dose-dependent. Half-maximal and maximal accumulation of the ( 3 H)IPs occur at ∼ 5 μM and ∼ 100 μM carbachol, respectively; values close to those seen in intact cells. GTPγS alone stimulates formation of the ( 3 H)IPs after a brief lag time. The combination of GTPγS and carbachol both increases the rate of, and decreases the lag in, formation of the ( 3 H)IPs. LiCl increases ( 3 H)IP and IP2, but not IP3, accumulation; while 2,3-diphosphoglycerate substantially increases that of ( 3 H)IP3. GTPγS and carbachol cause formation of ( 3 H)IPs in the absence of Ca ++ , but formation induced by GTPγS with or without carbachol is Ca ++ -sensitive over a range of physiological concentrations. Although carbachol, Ca ++ , and GTPγS all have effects on formation of ( 3 H)IPs, GTPγS appears to be a primary and obligatory regulator of phosphoinositide hydrolysis in the permeabilized 1321N1 astrocytoma cell

  5. Identification of sugarcane genes involved in the purine synthesis pathway

    Directory of Open Access Journals (Sweden)

    Mario A. Jancso

    2001-12-01

    Full Text Available Nucleotide synthesis is of central importance to all cells. In most organisms, the purine nucleotides are synthesized de novo from non-nucleotide precursors such as amino acids, ammonia and carbon dioxide. An understanding of the enzymes involved in sugarcane purine synthesis opens the possibility of using these enzymes as targets for chemicals which may be effective in combating phytopathogen. Such an approach has already been applied to several parasites and types of cancer. The strategy described in this paper was applied to identify sugarcane clusters for each step of the de novo purine synthesis pathway. Representative sequences of this pathway were chosen from the National Center for Biotechnology Information (NCBI database and used to search the translated sugarcane expressed sequence tag (SUCEST database using the available basic local alignment search tool (BLAST facility. Retrieved clusters were further tested for the statistical significance of the alignment by an implementation (PRSS3 of the Monte Carlo shuffling algorithm calibrated using known protein sequences of divergent taxa along the phylogenetic tree. The sequences were compared to each other and to the sugarcane clusters selected using BLAST analysis, with the resulting table of p-values indicating the degree of divergence of each enzyme within different taxa and in relation to the sugarcane clusters. The results obtained by this strategy allowed us to identify the sugarcane proteins participating in the purine synthesis pathway.A via de síntese de purino nucleotídeos é considerada uma via de central importância para todas as células. Na maioria dos organismos, os purino nucleotídeos são sintetizados ''de novo'' a partir de precursores não-nucleotídicos como amino ácidos, amônia e dióxido de carbono. O conhecimento das enzimas envolvidas na via de síntese de purinas da cana-de-açúcar vai abrir a possibilidade do uso dessas enzimas como alvos no desenho

  6. Bias of purine stretches in sequenced chromosomes

    DEFF Research Database (Denmark)

    Ussery, David; Soumpasis, Dikeos Mario; Brunak, Søren

    2002-01-01

    /pur tracts was slightly less than expected, with an average of 0.8%. One of the most surprising findings is a clear difference in the length distributions of the regions studied between prokaryotes and eukaryotes. Whereas short-range correlations can explain the length distributions in prokaryotes......, in eukaryotes there is an abundance of long stretches of purines or alternating purine/pyrimidine tracts, which cannot be explained in this way; these sequences are likely to play an important role in eukaryotic chromosome organisation....

  7. Crystallographic and single-particle analyses of native- and nucleotide-bound forms of the cystic fibrosis transmembrane conductance regulator (CFTR) protein.

    Science.gov (United States)

    Awayn, N H; Rosenberg, M F; Kamis, A B; Aleksandrov, L A; Riordan, J R; Ford, R C

    2005-11-01

    Cystic fibrosis, one of the major human inherited diseases, is caused by defects in the CFTR (cystic fibrosis transmembrane conductance regulator), a cell-membrane protein. CFTR acts as a chloride channel which can be opened by ATP. Low-resolution structural studies of purified recombinant human CFTR are described in the present paper. Localization of the C-terminal decahistidine tag in CFTR was achieved by Ni2+-nitriloacetate nanogold labelling, followed by electron microscopy and single-particle analysis. The presence of the gold label appears to improve the single-particle-alignment procedure. Projection structures of CFTR from two-dimensional crystals analysed by electron crystallography displayed two alternative conformational states in the presence of nucleotide and nanogold, but only one form of the protein was observed in the quiescent (nucleotide-free) state.

  8. Characterization of a depurinated-DNA purine-base-insertion activity from Drosophila.

    Science.gov (United States)

    Deutsch, W A; Spiering, A L

    1985-01-01

    An activity that binds preferentially to depurinated DNA and inserts purines into those sites was partially purified from Drosophila melanogaster embryos. The protein has a sedimentation coefficient of 4.9 S and is devoid of AP (apurinic/apyrimidinic) endonuclease activity. Upon incorporation of purines into apurinic DNA, the number of alkali-labile sites decreases, thus establishing the conversion of depurinated sites into normal nucleotides. The activity requires K+, and is totally inhibited by caffeine or EDTA. Guanine is specifically incorporated into partially depurinated poly(dG-dC) and adenine is specifically incorporated into poly(dA-dT), thus demonstrating the apparent template specificity of the enzyme. PMID:2417589

  9. Genetics Home Reference: purine nucleoside phosphorylase deficiency

    Science.gov (United States)

    ... the expand/collapse boxes. Description Purine nucleoside phosphorylase deficiency is one of several disorders that damage the immune system and cause severe combined immunodeficiency (SCID). People with SCID lack virtually all immune protection from foreign invaders such as bacteria, viruses, and ...

  10. "Plug and play" logic gates based on fluorescence switching regulated by self-assembly of nucleotide and lanthanide ions.

    Science.gov (United States)

    Pu, Fang; Ren, Jinsong; Qu, Xiaogang

    2014-06-25

    Molecular logic gates in response to chemical, biological, or optical input signals at a molecular level have received much interest over the past decade. Herein, we construct "plug and play" logic systems based on the fluorescence switching of guest molecules confined in coordination polymer nanoparticles generated from nucleotide and lanthanide ions. In the system, the addition of new modules directly enables new logic functions. PASS 0, YES, PASS 1, NOT, IMP, OR, and AND gates are successfully constructed in sequence. Moreover, different logic gates (AND, INH, and IMP) can be constructed using different guest molecules and the same input combinations. The work will be beneficial to the future logic design and expand the applications of coordination polymers.

  11. Regulation of formyl peptide receptor binding to rabbit neutrophil plasma membranes. Use of monovalent cations, guanine nucleotides, and bacterial toxins to discriminate among different states of the receptor

    International Nuclear Information System (INIS)

    Feltner, D.E.; Marasco, W.A.

    1989-01-01

    The regulation by monovalent cations, guanine nucleotides, and bacterial toxins of [3H]FMLP binding to rabbit neutrophil plasma membranes was studied by using dissociation techniques to identify regulatory effects on separate receptor states. Under conditions of low receptor occupancy (1 nM [3H]FMLP) and in both Na+ and K+ buffers, dissociation is heterogenous, displaying two distinct, statistically significant off rates. [3H]FMLP binding was enhanced by substituting other monovalent cations for Na+. In particular, enhanced binding in the presence of K+ relative to Na+ was caused by additional binding to both rapidly and slowly dissociating receptors. Three receptor dissociation rates, two of which appear to correspond to the two affinity states detected in equilibrium binding studies, were defined by specific GTP and pertussis toxin (PT) treatments. Neither GTP, nor PT or cholera toxins (CT) had an effect on the rate of dissociation of [3H]FMLP from the rapidly dissociating form of the receptor. Both 100 microM GTP and PT treatments increased the percentage of rapidly dissociating receptors, correspondingly decreasing the percentage of slowly dissociating receptors. The observed changes in the rapidly and slowly dissociating receptors after GTP, PT, and CT treatments were caused by an absolute decrease in the amount of binding to the slowly dissociating receptors. However, complete inhibition of slowly dissociating receptor binding by GTP, PT, or both was never observed. Both GTP and PT treatments, but not CT treatment, increased by two-fold the rate of dissociation of 1 nM [3H]FMLP from the slowly dissociating form of the receptor, resulting in a third dissociation rate. Thus, slowly dissociating receptors comprise two different receptor states, a G protein-associated guanine nucleotide and PT-sensitive state and a guanine nucleotide-insensitive state

  12. BIG1, a brefeldin A-inhibited guanine nucleotide-exchange protein regulates neurite development via PI3K-AKT and ERK signaling pathways.

    Science.gov (United States)

    Zhou, C; Li, C; Li, D; Wang, Y; Shao, W; You, Y; Peng, J; Zhang, X; Lu, L; Shen, X

    2013-12-19

    The elongation of neuron is highly dependent on membrane trafficking. Brefeldin A (BFA)-inhibited guanine nucleotide-exchange protein 1 (BIG1) functions in the membrane trafficking between the Golgi apparatus and the plasma membrane. BFA, an uncompetitive inhibitor of BIG1 can inhibit neurite outgrowth and polarity development. In this study, we aimed to define the possible role of BIG1 in neurite development and to further investigate the potential mechanism. By immunostaining, we found that BIG1 was extensively colocalized with synaptophysin, a marker for synaptic vesicles in soma and partly in neurites. The amount of both protein and mRNA of BIG1 were up-regulated during rat brain development. BIG1 depletion significantly decreased the neurite length and inhibited the phosphorylation of phosphatidylinositide 3-kinase (PI3K) and protein kinase B (AKT). Inhibition of BIG1 guanine nucleotide-exchange factor (GEF) activity by BFA or overexpression of the dominant-negative BIG1 reduced PI3K and AKT phosphorylation, indicating regulatory effects of BIG1 on PI3K-AKT signaling pathway is dependent on its GEF activity. BIG1 siRNA or BFA treatment also significantly reduced extracellular signal-regulated kinase (ERK) phosphorylation. Overexpression of wild-type BIG1 significantly increased ERK phosphorylation, but the dominant-negative BIG1 had no effect on ERK phosphorylation, indicating the involvement of BIG1 in ERK signaling regulation may not be dependent on its GEF activity. Our result identified a novel function of BIG1 in neurite development. The newly recognized function integrates the function of BIG1 in membrane trafficking with the activation of PI3K-AKT and ERK signaling pathways which are critical in neurite development. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  13. Classifying Coding DNA with Nucleotide Statistics

    Directory of Open Access Journals (Sweden)

    Nicolas Carels

    2009-10-01

    Full Text Available In this report, we compared the success rate of classification of coding sequences (CDS vs. introns by Codon Structure Factor (CSF and by a method that we called Universal Feature Method (UFM. UFM is based on the scoring of purine bias (Rrr and stop codon frequency. We show that the success rate of CDS/intron classification by UFM is higher than by CSF. UFM classifies ORFs as coding or non-coding through a score based on (i the stop codon distribution, (ii the product of purine probabilities in the three positions of nucleotide triplets, (iii the product of Cytosine (C, Guanine (G, and Adenine (A probabilities in the 1st, 2nd, and 3rd positions of triplets, respectively, (iv the probabilities of G in 1st and 2nd position of triplets and (v the distance of their GC3 vs. GC2 levels to the regression line of the universal correlation. More than 80% of CDSs (true positives of Homo sapiens (>250 bp, Drosophila melanogaster (>250 bp and Arabidopsis thaliana (>200 bp are successfully classified with a false positive rate lower or equal to 5%. The method releases coding sequences in their coding strand and coding frame, which allows their automatic translation into protein sequences with 95% confidence. The method is a natural consequence of the compositional bias of nucleotides in coding sequences.

  14. The Stringent Response Induced by Phosphate Limitation Promotes Purine Salvage in Agrobacterium fabrum.

    Science.gov (United States)

    Sivapragasam, Smitha; Deochand, Dinesh K; Meariman, Jacob K; Grove, Anne

    2017-10-31

    Agrobacterium fabrum induces tumor growth in susceptible plant species. The upregulation of virulence genes that occurs when the bacterium senses plant-derived compounds is enhanced by acidic pH and limiting inorganic phosphate. Nutrient starvation may also trigger the stringent response, and purine salvage is among the pathways expected to be favored under such conditions. We show here that phosphate limitation induces the stringent response, as evidenced by production of (p)ppGpp, and that the xdhCSML operon encoding the purine salvage enzyme xanthine dehydrogenase is upregulated ∼15-fold. The xdhCSML operon is under control of the TetR family transcription factor XdhR; direct binding of ppGpp to XdhR attenuates DNA binding, and the enhanced xdhCSML expression correlates with increased cellular levels of (p)ppGpp. Xanthine dehydrogenase may also divert purines away from salvage pathways to form urate, the ligand for the transcription factor PecS, which in the plant pathogen Dickeya dadantii is a key regulator of virulence gene expression. However, urate levels remain low under conditions that produce increased levels of xdhCSML expression, and neither acidic pH nor limiting phosphate results in induction of genes under control of PecS. Instead, expression of such genes is induced only by externally supplemented urate. Taken together, our data indicate that purine salvage is favored during the stringent response induced by phosphate starvation, suggesting that control of this pathway may constitute a novel approach to modulating virulence. Because bacterial purine catabolism appears to be unaffected, as evidenced by the absence of urate accumulation, we further propose that the PecS regulon is induced by only host-derived urate.

  15. Modeling compositional dynamics based on GC and purine contents of protein-coding sequences

    KAUST Repository

    Zhang, Zhang; Yu, Jun

    2010-01-01

    Background: Understanding the compositional dynamics of genomes and their coding sequences is of great significance in gaining clues into molecular evolution and a large number of publically-available genome sequences have allowed us to quantitatively predict deviations of empirical data from their theoretical counterparts. However, the quantification of theoretical compositional variations for a wide diversity of genomes remains a major challenge.Results: To model the compositional dynamics of protein-coding sequences, we propose two simple models that take into account both mutation and selection effects, which act differently at the three codon positions, and use both GC and purine contents as compositional parameters. The two models concern the theoretical composition of nucleotides, codons, and amino acids, with no prerequisite of homologous sequences or their alignments. We evaluated the two models by quantifying theoretical compositions of a large collection of protein-coding sequences (including 46 of Archaea, 686 of Bacteria, and 826 of Eukarya), yielding consistent theoretical compositions across all the collected sequences.Conclusions: We show that the compositions of nucleotides, codons, and amino acids are largely determined by both GC and purine contents and suggest that deviations of the observed from the expected compositions may reflect compositional signatures that arise from a complex interplay between mutation and selection via DNA replication and repair mechanisms.Reviewers: This article was reviewed by Zhaolei Zhang (nominated by Mark Gerstein), Guruprasad Ananda (nominated by Kateryna Makova), and Daniel Haft. 2010 Zhang and Yu; licensee BioMed Central Ltd.

  16. Modeling compositional dynamics based on GC and purine contents of protein-coding sequences

    KAUST Repository

    Zhang, Zhang

    2010-11-08

    Background: Understanding the compositional dynamics of genomes and their coding sequences is of great significance in gaining clues into molecular evolution and a large number of publically-available genome sequences have allowed us to quantitatively predict deviations of empirical data from their theoretical counterparts. However, the quantification of theoretical compositional variations for a wide diversity of genomes remains a major challenge.Results: To model the compositional dynamics of protein-coding sequences, we propose two simple models that take into account both mutation and selection effects, which act differently at the three codon positions, and use both GC and purine contents as compositional parameters. The two models concern the theoretical composition of nucleotides, codons, and amino acids, with no prerequisite of homologous sequences or their alignments. We evaluated the two models by quantifying theoretical compositions of a large collection of protein-coding sequences (including 46 of Archaea, 686 of Bacteria, and 826 of Eukarya), yielding consistent theoretical compositions across all the collected sequences.Conclusions: We show that the compositions of nucleotides, codons, and amino acids are largely determined by both GC and purine contents and suggest that deviations of the observed from the expected compositions may reflect compositional signatures that arise from a complex interplay between mutation and selection via DNA replication and repair mechanisms.Reviewers: This article was reviewed by Zhaolei Zhang (nominated by Mark Gerstein), Guruprasad Ananda (nominated by Kateryna Makova), and Daniel Haft. 2010 Zhang and Yu; licensee BioMed Central Ltd.

  17. Roles of the Amino Group of Purine Bases in the Thermodynamic Stability of DNA Base Pairing

    Directory of Open Access Journals (Sweden)

    Shu-ichi Nakano

    2014-08-01

    Full Text Available The energetic aspects of hydrogen-bonded base-pair interactions are important for the design of functional nucleotide analogs and for practical applications of oligonucleotides. The present study investigated the contribution of the 2-amino group of DNA purine bases to the thermodynamic stability of oligonucleotide duplexes under different salt and solvent conditions, using 2'-deoxyriboinosine (I and 2'-deoxyribo-2,6-diaminopurine (D as non-canonical nucleotides. The stability of DNA duplexes was changed by substitution of a single base pair in the following order: G•C > D•T ≈ I•C > A•T > G•T > I•T. The apparent stabilization energy due to the presence of the 2-amino group of G and D varied depending on the salt concentration, and decreased in the water-ethanol mixed solvent. The effects of salt concentration on the thermodynamics of DNA duplexes were found to be partially sequence-dependent, and the 2-amino group of the purine bases might have an influence on the binding of ions to DNA through the formation of a stable base-paired structure. Our results also showed that physiological salt conditions were energetically favorable for complementary base recognition, and conversely, low salt concentration media and ethanol-containing solvents were effective for low stringency oligonucleotide hybridization, in the context of conditions employed in this study.

  18. Distinct Purine Distribution in Carbonaceous Chondrites

    Science.gov (United States)

    Callahan, Michael P.; Smith, Karen E.; Cleaves, Henderson J.; Ruzicka, Josef; Stern, Jennifer C.; Glavin, Daniel P.; House, Christopher H.; Dworkin, Jason P.

    2011-01-01

    Carbonaceous chondrite meteorites are known to contain a diverse suite of organic compounds, many of which are essential components of biochemistry. Amino acids, which are the monomers of proteins, have been extensively studied in such meteorites (e.g. Botta and Bada 2002; Pizzarello et aI., 2006). The origin of amino acids in meteorites has been firmly established as extraterrestrial based on their detection typically as racemic mixtures of amino acids, the presence of many non-protein amino acids, and non-terrestrial values for compound-specific deuterium, carbon, and nitrogen isotopic measurements. In contrast to amino acids, nucleobases in meteorites have been far less studied. Nucleobases are substituted one-ring (pyrimidine) or two-ring (purine) nitrogen heterocyclic compounds and serve as the information carriers of nucleic acids and in numerous coenzymes. All of the purines (adenine, guanine, hypoxanthine, and xanthine) and pyrimidines (uracil) previously reported in meteorites are biologically common and could be interpreted as the result of terrestrial contamination (e.g. van del' Velden and Schwartz, 1974.) Unlike other meteoritic organics, there have been no observations of stochastic molecular diversity of purines and pyrimidines in meteorites, which has been a criterion for establishing extraterrestrial origin. Maltins et al. (2008) performed compound-specific stable carbon isotope measurements for uracil and xanthine in the Murchison meteorite. They assigned a non-terrestrial origin for these nucleobases; however, the possibility that interfering indigenous molecules (e.g. carboxylic acids) contributed to the 13C-enriched isotope values for these nucleobases cannot be completely ruled out. Thus, the origin of these meteoritic nucleobases has never been established unequivocally. Here we report on our investigation of extracts of II different carbonaceous chondrites covering various petrographic types (Cl, CM, and CR) and degrees of aqueous alteration

  19. Structure, stability, and thermodynamics of a short intermolecular purine-purine-pyrimidine triple helix

    International Nuclear Information System (INIS)

    Pilch, D.S.; Shafer, R.H.; Levenson, C.

    1991-01-01

    The authors have investigated the structure and physical chemistry of the d(C 3 T 4 C 3 )·2[d(G 3 A 4 G 3 )] triple helix by polyacrylamide gel electrophoresis (PAGE), 1 H NMR, and ultraviolet (UV) absorption spectroscopy. The triplex was stabilized with MgCl 2 at neutral pH. PAGE studies verify the stoichiometry of the strands comprising the triplex and indicate that the orientation of the third strand in purine-purine-pyrimidine (pur-pur-pyr) triplexes is antiparallel with respect to the purine strand of the underlying duplex. Imino proton NMR spectra provide evidence for the existence of new purine-purine (pur·pur) hydrogen bonds, in addition to those of the Watson-Crick (W-C) base pairs, in the triplex structure. These new hydrogen bonds are likely to correspond to the interaction between third-strand guanine NH1 imino protons and the N7 atoms of guanine residues on the puring strand of the underlying duplex. Thermal denaturation of the triplex proceeds to single strands in one step, under the conditions used in this study. Binding of the third strand appears to enhance the thermal stability of the duplex by 1-3 C, depending on the DNA concentration. This marked enhancement in stability, coupled with the lack of an acidic pH requirement, suggests that pur-pur-pyr triplexes are appealing choices for use in applications involving oligonucleotide targeting of duplex DNA in vitro and in vivo

  20. Heterosis and heritability estimates of purine alkaloids and ...

    African Journals Online (AJOL)

    Dry cocoa beans displayed high content of purine alkaloids (2.1 and 8.8 mg g-1 for caffein and theobromine, respectively), and polyphenols (25 and 2978 μg g-1 for catechin and epicatechin, respectively). Among the five cocoa clones, SNK16 was the highest in purine alkaloid (caffein and theobromin) and flavanol ...

  1. 1,3,5-Triazine-based analogues of purine: from isosteres to privileged scaffolds in medicinal chemistry.

    Science.gov (United States)

    Lim, Felicia Phei Lin; Dolzhenko, Anton V

    2014-10-06

    Purines can be considered as the most ubiquitous and functional N-heterocyclic compounds in nature. Structural modifications of natural purines, particularly using isosteric ring systems, have been in the focus of many drug discovery programs. Fusion of 1,3,5-triazine ring with pyrrole, pyrazole, imidazole, 1,2,3-triazole or 1,2,4-triazole results in seven bicyclic heterocyclic systems isosteric to purine. Application of the isosterism concept for the development of new compounds with therapeutic potential in areas involving purinergic regulation or purine metabolism led to significant advances in medicinal chemistry of the azolo[1,3,5]triazines. These 1,3,5-triazine-based purine-like scaffolds significantly increase level of molecular diversity and allow covering chemical space in the important areas of medicinal chemistry. Some of these azolo[1,3,5]triazine systems have become privileged scaffolds in the development of inhibitors of various kinases, phosphodiesterase, xanthine oxidase, and thymidine phosphorylase, antagonists of adenosine and corticotropin-releasing hormone receptors, anticancer and antiviral agents. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  2. Hormone regulation system and cyclic nucleotids in the Chernobyl accident liquidators with doses absorbed less then 1 Gy

    International Nuclear Information System (INIS)

    Kovalenko, A.N.

    1997-01-01

    During 6 years after the accident (1987-1992) a functional state of endocrine system that regulate the adaptation, reproduction, metabolism, vessels tonicity and water-electrolyte balance were investigated in 249 liquidators with doses absorbed less then 1 Gy. The changes of these systems activity in state of basal secretion and peculiarities of their reactions under influence of perturbation (adrenaline, insulin) were revealed. Post-irradiation endocrinopathy was characterized and its role in decrease of the organism's adaptation and in mechanism of sanogenesis and pathogenesis was found. (author)

  3. HHR23A, a human homolog of Saccharomyces cerevisiae Rad23, regulates xeroderma pigmentosum C protein and is required for nucleotide excision repair

    International Nuclear Information System (INIS)

    Hsieh, Hui-Chuan; Hsieh, Yi-Hsuan; Huang, Yu-Hsin; Shen, Fan-Ching; Tsai, Han-Ni; Tsai, Jui-He; Lai, Yu-Ting; Wang, Yu-Ting; Chuang, Woei-Jer; Huang, Wenya

    2005-01-01

    HHR23A and hHR23B are the human homologs of Saccharomyces cerevisiae Rad23. hHR23B is associated with the nucleotide excision repair (NER) factor xeroderma pigmentosum C (XPC) protein and is required for global genome repair. The function of hHR23A is not yet clear. In this study, the potential function of the hHR23A protein was investigated using RNA interference techniques. The hHR23A knock-down (KD) construct diminished the RNA level of hHR23A protein by approximately 60%, and it did not interfere with expression of the hHR23B gene. Based on Southwestern immunoblot and host-cell reactivation assays, hHR23A KD cells were found to be deficient in DNA repair activity against the DNA damage caused by UVC irradiation. In these hHR23A KD cells, the XPC gene was not normally induced by UVC irradiation, indicating that the hHR23A protein is involved in NER through regulation of the DNA damage recognition protein XPC. Co-immunoprecipitation experiments revealed that hHR23A was associated with a small portion of hHR23B and the majority of p53 protein, indicating that hHR23A regulates the function of XPC by its association with the NER activator p53

  4. A Histidine pH sensor regulates activation of the Ras-specific guanine nucleotide exchange factor RasGRP1.

    Science.gov (United States)

    Vercoulen, Yvonne; Kondo, Yasushi; Iwig, Jeffrey S; Janssen, Axel B; White, Katharine A; Amini, Mojtaba; Barber, Diane L; Kuriyan, John; Roose, Jeroen P

    2017-09-27

    RasGRPs are guanine nucleotide exchange factors that are specific for Ras or Rap, and are important regulators of cellular signaling. Aberrant expression or mutation of RasGRPs results in disease. An analysis of RasGRP1 SNP variants led to the conclusion that the charge of His 212 in RasGRP1 alters signaling activity and plasma membrane recruitment, indicating that His 212 is a pH sensor that alters the balance between the inactive and active forms of RasGRP1. To understand the structural basis for this effect we compared the structure of autoinhibited RasGRP1, determined previously, to those of active RasGRP4:H-Ras and RasGRP2:Rap1b complexes. The transition from the autoinhibited to the active form of RasGRP1 involves the rearrangement of an inter-domain linker that displaces inhibitory inter-domain interactions. His 212 is located at the fulcrum of these conformational changes, and structural features in its vicinity are consistent with its function as a pH-dependent switch.

  5. Stabilization of a nucleotide-binding domain of the cystic fibrosis transmembrane conductance regulator yields insight into disease-causing mutations.

    Science.gov (United States)

    Vernon, Robert M; Chong, P Andrew; Lin, Hong; Yang, Zhengrong; Zhou, Qingxian; Aleksandrov, Andrei A; Dawson, Jennifer E; Riordan, John R; Brouillette, Christie G; Thibodeau, Patrick H; Forman-Kay, Julie D

    2017-08-25

    Characterization of the second nucleotide-binding domain (NBD2) of the cystic fibrosis transmembrane conductance regulator (CFTR) has lagged behind research into the NBD1 domain, in part because NBD1 contains the F508del mutation, which is the dominant cause of cystic fibrosis. Research on NBD2 has also been hampered by the overall instability of the domain and the difficulty of producing reagents. Nonetheless, multiple disease-causing mutations reside in NBD2, and the domain is critical for CFTR function, because channel gating involves NBD1/NBD2 dimerization, and NBD2 contains the catalytically active ATPase site in CFTR. Recognizing the paucity of structural and biophysical data on NBD2, here we have defined a bioinformatics-based method for manually identifying stabilizing substitutions in NBD2, and we used an iterative process of screening single substitutions against thermal melting points to both produce minimally mutated stable constructs and individually characterize mutations. We present a range of stable constructs with minimal mutations to help inform further research on NBD2. We have used this stabilized background to study the effects of NBD2 mutations identified in cystic fibrosis (CF) patients, demonstrating that mutants such as N1303K and G1349D are characterized by lower stability, as shown previously for some NBD1 mutations, suggesting a potential role for NBD2 instability in the pathology of CF. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Nucleotide sequences of the Erwinia chrysanthemi ogl and pelE genes negatively regulated by the kdgR gene product.

    Science.gov (United States)

    Reverchon, S; Huang, Y; Bourson, C; Robert-Baudouy, J

    1989-12-21

    The nucleotide sequences of the coding and regulatory regions of the genes encoding oligoglacturonate lyase (OGL) and pectate lyase e isoenzyme (PLe) from Erwinia chrysanthemi 3937 were determined. The ogl sequence contains an open reading frame (ORF) of 1164 bp coding for a 388-amino acid (aa) polypeptide with a predicted Mr of 44,124. A possible transcriptional start signal showing homology with the Escherichia coli promoter consensus sequence was detected. In addition, a sequence 3' to the coding region was found to be able to form a secondary structure which may function as an Rho-independent transcriptional termination signal. For the pelE sequence, a long ORF of 1212 bp coding for a 404-aa polypeptide was detected. PLe is secreted into the external medium by E. chrysanthemi, and a potential signal peptide sequence was identified in the pelE gene. In the 5' upstream pelE coding region, a putative promoter resembling E. coli promoter consensus sequences was detected. Furthermore, the region immediately 3' to the pelE translational stop codon may function as an Rho-independent translational termination signal. In strain 3937, the synthesis of OGL and PLe, as well as the other enzymes involved in the pectin-degradative pathway (particularly the kdgT product), are known to be regulated by the KdgR repressor, which mediates galacturonate and polygalacturonate induction. Synthesis of these enzymes is also regulated by the CRP-cAMP complex which mediates catabolite repression. Analysis of the regulatory regions of ogl and pelE allowed us to identify possible CRP-binding sites for these two genes.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. The role of an ancestral hyperpolarization-activated cyclic nucleotide-gated K+ channel in branchial acid-base regulation in the green crab, Carcinus maenas.

    Science.gov (United States)

    Fehsenfeld, Sandra; Weihrauch, Dirk

    2016-03-01

    Numerous electrophysiological studies on branchial K(+) transport in brachyuran crabs have established an important role for potassium channels in osmoregulatory ion uptake and ammonia excretion in the gill epithelium of decapod crustaceans. However, hardly anything is known of the actual nature of these channels in crustaceans. In the present study, the identification of a hyperpolarization-activated cyclic nucleotide-gated potassium channel (HCN) in the transcriptome of the green crab Carcinus maenas and subsequent performance of quantitative real-time PCR revealed the ubiquitous expression of this channel in this species. Even though mRNA expression levels in the cerebral ganglion were found to be approximately 10 times higher compared with all other tissues, posterior gills still expressed significant levels of HCN, indicating an important role for this transporter in branchial ion regulation. The relatively unspecific K(+)-channel inhibitor Ba(2+), as well as the HCN-specific blocker ZD7288, as applied in gill perfusion experiments and electrophysiological studies employing the split gill lamellae revealed the presence of at least two different K(+)/NH4(+)-transporting structures in the branchial epithelium of C. maenas. Furthermore, HCN mRNA levels in posterior gill 7 decreased significantly in response to the respiratory or metabolic acidosis that was induced by acclimation of green crabs to high environmental PCO2 and ammonia, respectively. Consequently, the present study provides first evidence that HCN-promoted NH4(+) epithelial transport is involved in both branchial acid-base and ammonia regulation in an invertebrate. © 2016. Published by The Company of Biologists Ltd.

  8. Impact of the [delta]F508 Mutation in First Nucleotide-binding Domain of Human Cystic Fibrosis Transmembrane Conductance Regulator on Domain Folding and Structure

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Hal A.; Zhao, Xun; Wang, Chi; Sauder, J. Michael; Rooney, Isabelle; Noland, Brian W.; Lorimer, Don; Kearins, Margaret C.; Conners, Kris; Condon, Brad; Maloney, Peter C.; Guggino, William B.; Hunt, John F.; Emtage, Spencer (SG); (Columbia); (JHU)

    2010-07-19

    Cystic fibrosis is caused by defects in the cystic fibrosis transmembrane conductance regulator (CFTR), commonly the deletion of residue Phe-508 (DeltaF508) in the first nucleotide-binding domain (NBD1), which results in a severe reduction in the population of functional channels at the epithelial cell surface. Previous studies employing incomplete NBD1 domains have attributed this to aberrant folding of DeltaF508 NBD1. We report structural and biophysical studies on complete human NBD1 domains, which fail to demonstrate significant changes of in vitro stability or folding kinetics in the presence or absence of the DeltaF508 mutation. Crystal structures show minimal changes in protein conformation but substantial changes in local surface topography at the site of the mutation, which is located in the region of NBD1 believed to interact with the first membrane spanning domain of CFTR. These results raise the possibility that the primary effect of DeltaF508 is a disruption of proper interdomain interactions at this site in CFTR rather than interference with the folding of NBD1. Interestingly, increases in the stability of NBD1 constructs are observed upon introduction of second-site mutations that suppress the trafficking defect caused by the DeltaF508 mutation, suggesting that these suppressors might function indirectly by improving the folding efficiency of NBD1 in the context of the full-length protein. The human NBD1 structures also solidify the understanding of CFTR regulation by showing that its two protein segments that can be phosphorylated both adopt multiple conformations that modulate access to the ATPase active site and functional interdomain interfaces.

  9. Coordinated regulation by two VPS9 domain-containing guanine nucleotide exchange factors in small GTPase Rab5 signaling pathways in fission yeast

    International Nuclear Information System (INIS)

    Tsukamoto, Yuta; Kagiwada, Satoshi; Shimazu, Sayuri; Takegawa, Kaoru; Noguchi, Tetsuko; Miyamoto, Masaaki

    2015-01-01

    The small GTPase Rab5 is reported to regulate various cellular functions, such as vesicular transport and endocytosis. VPS9 domain-containing proteins are thought to activate Rab5(s) by their guanine-nucleotide exchange activities. Numerous VPS9 proteins have been identified and are structurally conserved from yeast to mammalian cells. However, the functional relationships among VPS9 proteins in cells remain unclear. Only one Rab5 and two VPS9 proteins were identified in the Schizosaccharomyces pombe genome. Here, we examined the cellular function of two VPS9 proteins and the relationship between these proteins in cellular functions. Vps901-GFP and Vps902-GFP exhibited dotted signals in vegetative and differentiated cells. vps901 deletion mutant (Δvps901) cells exhibited a phenotype deficient in the mating process and responses to high concentrations of ions, such as calcium and metals, and Δvps901Δvps902 double mutant cells exhibited round cell shapes similar to ypt5-909 (Rab5 mutant allele) cells. Deletion of both vps901 and vps902 genes completely abolished the mating process and responses to various stresses. A lack of vacuole formation and aberrant inner cell membrane structures were also observed in Δvps901Δvps902 cells by electron microscopy. These data strongly suggest that Vps901 and Vps902 are cooperatively involved in the regulation of cellular functions, such as cell morphology, sexual development, response to ion stresses, and vacuole formation, via Rab5 signaling pathways in fission yeast cells. - Highlights: • Roles of Rab5 activator VPS9 proteins in cellular functions. • Cooperation between VPS9 proteins in Rab5 signaling pathway. • Roles of each VPS9 protein in Rab5 signaling pathway are discussed

  10. Coordinated regulation by two VPS9 domain-containing guanine nucleotide exchange factors in small GTPase Rab5 signaling pathways in fission yeast

    Energy Technology Data Exchange (ETDEWEB)

    Tsukamoto, Yuta [Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Kagiwada, Satoshi [Department of Biological Sciences, Faculty of Science, Nara Women' s University, Kitauoyanishi-machi, Nara 630-8506 (Japan); Shimazu, Sayuri [Center for Supports to Research and Education Activities, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Takegawa, Kaoru [Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Noguchi, Tetsuko [Department of Biological Sciences, Faculty of Science, Nara Women' s University, Kitauoyanishi-machi, Nara 630-8506 (Japan); Miyamoto, Masaaki, E-mail: miya@kobe-u.ac.jp [Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Center for Supports to Research and Education Activities, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan)

    2015-03-20

    The small GTPase Rab5 is reported to regulate various cellular functions, such as vesicular transport and endocytosis. VPS9 domain-containing proteins are thought to activate Rab5(s) by their guanine-nucleotide exchange activities. Numerous VPS9 proteins have been identified and are structurally conserved from yeast to mammalian cells. However, the functional relationships among VPS9 proteins in cells remain unclear. Only one Rab5 and two VPS9 proteins were identified in the Schizosaccharomyces pombe genome. Here, we examined the cellular function of two VPS9 proteins and the relationship between these proteins in cellular functions. Vps901-GFP and Vps902-GFP exhibited dotted signals in vegetative and differentiated cells. vps901 deletion mutant (Δvps901) cells exhibited a phenotype deficient in the mating process and responses to high concentrations of ions, such as calcium and metals, and Δvps901Δvps902 double mutant cells exhibited round cell shapes similar to ypt5-909 (Rab5 mutant allele) cells. Deletion of both vps901 and vps902 genes completely abolished the mating process and responses to various stresses. A lack of vacuole formation and aberrant inner cell membrane structures were also observed in Δvps901Δvps902 cells by electron microscopy. These data strongly suggest that Vps901 and Vps902 are cooperatively involved in the regulation of cellular functions, such as cell morphology, sexual development, response to ion stresses, and vacuole formation, via Rab5 signaling pathways in fission yeast cells. - Highlights: • Roles of Rab5 activator VPS9 proteins in cellular functions. • Cooperation between VPS9 proteins in Rab5 signaling pathway. • Roles of each VPS9 protein in Rab5 signaling pathway are discussed.

  11. Prolonged fasting increases purine recycling in post-weaned northern elephant seals.

    Science.gov (United States)

    Soñanez-Organis, José Guadalupe; Vázquez-Medina, José Pablo; Zenteno-Savín, Tania; Aguilar, Andres; Crocker, Daniel E; Ortiz, Rudy M

    2012-05-01

    Northern elephant seals are naturally adapted to prolonged periods (1-2 months) of absolute food and water deprivation (fasting). In terrestrial mammals, food deprivation stimulates ATP degradation and decreases ATP synthesis, resulting in the accumulation of purines (ATP degradation byproducts). Hypoxanthine-guanine phosphoribosyl transferase (HGPRT) salvages ATP by recycling the purine degradation products derived from xanthine oxidase (XO) metabolism, which also promotes oxidant production. The contributions of HGPRT to purine recycling during prolonged food deprivation in marine mammals are not well defined. In the present study we cloned and characterized the complete and partial cDNA sequences that encode for HGPRT and xanthine oxidoreductase (XOR) in northern elephant seals. We also measured XO protein expression and circulating activity, along with xanthine and hypoxanthine plasma content in fasting northern elephant seal pups. Blood, adipose and muscle tissue samples were collected from animals after 1, 3, 5 and 7 weeks of their natural post-weaning fast. The complete HGPRT and partial XOR cDNA sequences are 771 and 345 bp long and encode proteins of 218 and 115 amino acids, respectively, with conserved domains important for their function and regulation. XOR mRNA and XO protein expression increased 3-fold and 1.7-fold with fasting, respectively, whereas HGPRT mRNA (4-fold) and protein (2-fold) expression increased after 7 weeks in adipose tissue and muscle. Plasma xanthine (3-fold) and hypoxanthine (2.5-fold) levels, and XO (1.7- to 20-fold) and HGPRT (1.5- to 1.7-fold) activities increased during the last 2 weeks of fasting. Results suggest that prolonged fasting in elephant seal pups is associated with increased capacity to recycle purines, which may contribute to ameliorating oxidant production and enhancing the supply of ATP, both of which would be beneficial during prolonged food deprivation and appear to be adaptive in this species.

  12. NUCLEOTIDES IN INFANT FEEDING

    Directory of Open Access Journals (Sweden)

    L.G. Mamonova

    2007-01-01

    Full Text Available The article reviews the application of nucleotides-metabolites, playing a key role in many biological processes, for the infant feeding. The researcher provides the date on the nucleotides in the women's milk according to the lactation stages. She also analyzes the foreign experience in feeding newborns with nucleotides-containing milk formulas. The article gives a comparison of nucleotides in the adapted formulas represented in the domestic market of the given products.Key words: children, feeding, nucleotides.

  13. An Expanding Role For Purine Uptake Permease (PUP -like Transporters In Plant Secondary Metabolism.

    Directory of Open Access Journals (Sweden)

    John G. Jelesko

    2012-05-01

    Full Text Available For the past decade, our understanding of the plant purine uptake permease (PUP transporter family of was primarily oriented on purine nucleobase substrates and their tissue-specific expression patterns in Arabidopsis. However, a tobacco PUP-like homolog demonstrating nicotine uptake permease (NUP activity was recently shown to affect both nicotine metabolism and root cell growth. These new findings expand the physiological role for PUP-like transporters to include plant secondary metabolism. Molecular evolution analyses of PUP-like transporters indicate they are distinct group within an ancient super family of drug and metabolite transporters (DMTs. The PUP-like family originated during terrestrial plant evolution sometime between the bryophytes and the lycophytes. A phylogenetic analysis indicates that the PUP-like transporters were likely were derived from a pre-existing nucleotide sugar transporter family within the DMT super family. Within the lycophyte Selaginella, there are three paralogous groups of PUP-like transporters. One of the three PUP-like paralogous groups showed an extensive pattern of gene duplication and diversification within the angiosperm lineage, whereas the other two more ancestral PUP-like paralogous groups did not. Biochemical characterization of four closely-related PUP-like paralogs together with model-based phylogenetic analyses indicate both subfunctionalization and neofunctionalization during the molecular evolution of angiosperm PUP-like transporters. These findings suggest that members of the PUP-like family of DMT transporters are likely involved in diverse primary and secondary plant metabolic pathways.

  14. Associations between purine metabolites and clinical symptoms in schizophrenia.

    Directory of Open Access Journals (Sweden)

    Jeffrey K Yao

    Full Text Available The antioxidant defense system, which is known to be dysregulated in schizophrenia, is closely linked to the dynamics of purine pathway. Thus, alterations in the homeostatic balance in the purine pathway may be involved in the pathophysiology of schizophrenia.Breakdown products in purine pathway were measured using high-pressure liquid chromatography coupled with a coulometric multi-electrode array system for 25 first-episode neuroleptic-naïve patients with schizophrenia at baseline and at 4-weeks following initiation of treatment with antipsychotic medication. Associations between these metabolites and clinical and neurological symptoms were examined at both time points. The ratio of uric acid and guanine measured at baseline predicted clinical improvement following four weeks of treatment with antipsychotic medication. Baseline levels of purine metabolites also predicted clinical and neurological symtpoms recorded at baseline; level of guanosine was associated with degree of clinical thought disturbance, and the ratio of xanthosine to guanosine at baseline predicted degree of impairment in the repetition and sequencing of actions.Findings suggest an association between optimal levels of purine byproducts and dynamics in clinical symptoms and adjustment, as well as in the integrity of sensory and motor processing. Taken together, alterations in purine catabolism may have clinical relevance in schizophrenia pathology.

  15. Brain purine metabolism and xanthine dehydrogenase/oxidase conversion in hyperammonemia are under control of NMDA receptors and nitric oxide.

    Science.gov (United States)

    Kaminsky, Yury; Kosenko, Elena

    2009-10-19

    In hyperammonemia, a decrease in brain ATP can be a result of adenine nucleotide catabolism. Xanthine dehydrogenase (XD) and xanthine oxidase (XO) are the end steps in the purine catabolic pathway and directly involved in depletion of the adenylate pool in the cell. Besides, XD can easily be converted to XO to produce reactive oxygen species in the cell. In this study, the effects of acute ammonia intoxication in vivo on brain adenine nucleotide pool and xanthine and hypoxanthine, the end degradation products of adenine nucleotides, during the conversion of XD to XO were studied. Injection of rats with ammonium acetate was shown to lead to the dramatic decrease in the ATP level, adenine nucleotide pool size and adenylate energy charge and to the great increase in hypoxanthine and xanthine 11 min after the lethal dose indicating rapid degradation of adenylates. Conversion of XD to XO in hyperammonemic rat brain was evidenced by elevated XO/XD activity ratio. Injection of MK-801, a NMDA receptor blocker, prevented ammonia-induced catabolism of adenine nucleotides and conversion of XD to XO suggesting that in vivo these processes are mediated by activation of NMDA receptors. The in vitro dose-dependent effects of sodium nitroprusside, a NO donor, on XD and XO activities are indicative of the direct modification of the enzymes by nitric oxide. This is the first report evidencing the increase in brain xanthine and hypoxanthine levels and adenine nucleotide breakdown in acute ammonia intoxication and NMDA receptor-mediated prevention of these alterations.

  16. Stable Human Hepatoma Cell Lines for Efficient Regulated Expression of Nucleoside/Nucleotide Analog Resistant and Vaccine Escape Hepatitis B Virus Variants and Woolly Monkey Hepatitis B Virus.

    Directory of Open Access Journals (Sweden)

    Xin Cheng

    Full Text Available Hepatitis B virus (HBV causes acute and chronic hepatitis B (CHB. Due to its error-prone replication via reverse transcription, HBV can rapidly evolve variants that escape vaccination and/or become resistant to CHB treatment with nucleoside/nucleotide analogs (NAs. This is particularly problematic for the first generation NAs lamivudine and adefovir. Though now superseded by more potent NAs, both are still widely used. Furthermore, resistance against the older NAs can contribute to cross-resistance against more advanced NAs. For lack of feasible HBV infection systems, the biology of such variants is not well understood. From the recent discovery of Na+-taurocholate cotransporting polypeptide (NTCP as an HBV receptor new in vitro infection systems are emerging, yet access to the required large amounts of virions, in particular variants, remains a limiting factor. Stably HBV producing cell lines address both issues by allowing to study intracellular viral replication and as a permanent source of defined virions. Accordingly, we generated a panel of new tetracycline regulated TetOFF HepG2 hepatoma cell lines which produce six lamivudine and adefovir resistance-associated and two vaccine escape variants of HBV as well as the model virus woolly monkey HBV (WMHBV. The cell line-borne viruses reproduced the expected NA resistance profiles and all were equally sensitive against a non-NA drug. The new cell lines should be valuable to investigate under standardized conditions HBV resistance and cross-resistance. With titers of secreted virions reaching >3 x 10(7 viral genome equivalents per ml they should also facilitate exploitation of the new in vitro infection systems.

  17. The radiation chemistry of the purine bases within DNA and related model compounds

    International Nuclear Information System (INIS)

    Cadet, J.; Berger, M.; Shaw, A.

    1986-01-01

    Both the direct and indirect effects of ionizing radiations are believed to contribute to the chemical changes induced in cellular DNA. Relevant information on the possible degradation pathways has been provided by studies using DNA model compounds, the major proportion of which have focused on pyrimidine components and sugar derivatives. With the development of powerful analytical tools such as high performance liquid chromatography and soft ionization mass spectrometry techniques, progress has recently been made in the elucidation of the nature of the radiation-induced chemical modifications of purine bases in DNA and related nucleosides and nucleotides. This short review details recent aspects of the radiation-induced degradation of adenine and guanine bases in DNA and its model compounds as the result of both direct and indirect effects. 11 refs., 2 figs., 1 tab

  18. The effect of cyclophosphamide and gamma irradiation on adenosine deaminase and purine nucleoside phosphorylase in mice

    International Nuclear Information System (INIS)

    Hosek, B.; Bohaecek, J.; Sikulova, J.

    1991-01-01

    Changes in ADA and PNP activities in the spleens and thymuses of mice were studied after a single administration of cyclophosphamide and after whole-body gamma irradiation, applied alone or three days after CY application, In the first days after the treatment the enzyme activities were significantly depressed with the exception of ADA in the spleen, where a high elevation in relation to controls was observed. During the regeneration period a pronounced rise of PNP activity in the spleen occurred mainly after a combined application of CY and irradiation. In the thymus the regeneration was manifested by a mild increase of both ADA and PNP activities towards control values. The findings suggest that the expressive changes of ADA and PNP activities, participating in the purine salvage pathway, may, after a cytotoxic treatment, influence the nucleotide pool and DNA synthesis in lymphoid organs

  19. Targeting a Novel Plasmodium falciparum Purine Recycling Pathway with Specific Immucillins

    International Nuclear Information System (INIS)

    Ting, L; Shi, W; Lewandowicz, A; Singh, V; Mwakingwe, A; Birck, M R; Taylor Ringia, E A; Bench, G; Madrid, D C; Tyler, P C; Evans, G B; Furneaux, R H; Schramm, V L; Kim, K.

    2004-01-01

    Plasmodium falciparum is unable to synthesize purine bases and relies upon purine salvage and purine recycling to meet its purine needs. We report that purines formed as products of the polyamine pathway are recycled in a novel pathway in which 5'-methylthioinosine is generated by adenosine deaminase. The action of P. falciparum purine nucleoside phosphorylase is a convergent step of purine salvage, converting both 5'-methylthioinosine and inosine to hypoxanthine. We used accelerator mass spectrometry to verify that 5'-methylthioinosine is an active nucleic acid precursor in P. falciparum. Prior studies have shown that inhibitors of purine salvage enzymes kill malaria, but potent malaria-specific inhibitors of these enzymes have not previously been described. 5'-methylthio-Immucillin-H, a transition state analogue inhibitor that is selective for malarial over human purine nucleoside phosphorylase, kills P. falciparum in culture. Immucillins are currently in clinical trials for other indications and may have application as antimalarials

  20. Purine Metabolism in Acute Cerebral Ischemia

    Directory of Open Access Journals (Sweden)

    Ye. V. Oreshnikov

    2008-01-01

    Full Text Available Objective: to study the specific features of purine metabolism in clinically significant acute cerebral ischemia. Subjects and materials. Three hundred and fifty patients with the acutest cerebral ischemic stroke were examined. The parameters of gas and electrolyte composition, acid-base balance, the levels of malonic dialdehyde, adenine, guanine, hypox-anthine, xanthine, and uric acid, and the activity of xanthine oxidase were determined in arterial and venous bloods and spinal fluid. Results. In ischemic stroke, hyperuricemia reflects the severity of cerebral metabolic disturbances, hemodynamic instability, hypercoagulation susceptiility, and the extent of neurological deficit. In ischemic stroke, hyperuri-corachia is accompanied by the higher spinal fluid levels of adenine, guanine, hypoxanthine, and xanthine and it is an indirect indicator of respiratory disorders of central genesis, systemic acidosis, hypercoagulation susceptibility, free radical oxidation activation, the intensity of a stressor response to cerebral ischemia, cerebral metabolic disturbances, the depth of reduced consciousness, and the severity of neurological deficit. Conclusion. The high venous blood activity of xanthine oxidase in ischemic stroke is associated with the better neurological parameters in all follow-up periods, the better early functional outcome, and lower mortality rates. Key words: hyperuricemia, stroke, xanthine oxidase, uric acid, cerebral ischemia.

  1. Classification of pseudo pairs between nucleotide bases and amino acids by analysis of nucleotide-protein complexes.

    Science.gov (United States)

    Kondo, Jiro; Westhof, Eric

    2011-10-01

    Nucleotide bases are recognized by amino acid residues in a variety of DNA/RNA binding and nucleotide binding proteins. In this study, a total of 446 crystal structures of nucleotide-protein complexes are analyzed manually and pseudo pairs together with single and bifurcated hydrogen bonds observed between bases and amino acids are classified and annotated. Only 5 of the 20 usual amino acid residues, Asn, Gln, Asp, Glu and Arg, are able to orient in a coplanar fashion in order to form pseudo pairs with nucleotide bases through two hydrogen bonds. The peptide backbone can also form pseudo pairs with nucleotide bases and presents a strong bias for binding to the adenine base. The Watson-Crick side of the nucleotide bases is the major interaction edge participating in such pseudo pairs. Pseudo pairs between the Watson-Crick edge of guanine and Asp are frequently observed. The Hoogsteen edge of the purine bases is a good discriminatory element in recognition of nucleotide bases by protein side chains through the pseudo pairing: the Hoogsteen edge of adenine is recognized by various amino acids while the Hoogsteen edge of guanine is only recognized by Arg. The sugar edge is rarely recognized by either the side-chain or peptide backbone of amino acid residues.

  2. The Purine Bias of Coding Sequences is Determined by Physicochemical Constraints on Proteins.

    Science.gov (United States)

    Ponce de Leon, Miguel; de Miranda, Antonio Basilio; Alvarez-Valin, Fernando; Carels, Nicolas

    2014-01-01

    For this report, we analyzed protein secondary structures in relation to the statistics of three nucleotide codon positions. The purpose of this investigation was to find which properties of the ribosome, tRNA or protein level, could explain the purine bias (Rrr) as it is observed in coding DNA. We found that the Rrr pattern is the consequence of a regularity (the codon structure) resulting from physicochemical constraints on proteins and thermodynamic constraints on ribosomal machinery. The physicochemical constraints on proteins mainly come from the hydropathy and molecular weight (MW) of secondary structures as well as the energy cost of amino acid synthesis. These constraints appear through a network of statistical correlations, such as (i) the cost of amino acid synthesis, which is in favor of a higher level of guanine in the first codon position, (ii) the constructive contribution of hydropathy alternation in proteins, (iii) the spatial organization of secondary structure in proteins according to solvent accessibility, (iv) the spatial organization of secondary structure according to amino acid hydropathy, (v) the statistical correlation of MW with protein secondary structures and their overall hydropathy, (vi) the statistical correlation of thymine in the second codon position with hydropathy and the energy cost of amino acid synthesis, and (vii) the statistical correlation of adenine in the second codon position with amino acid complexity and the MW of secondary protein structures. Amino acid physicochemical properties and functional constraints on proteins constitute a code that is translated into a purine bias within the coding DNA via tRNAs. In that sense, the Rrr pattern within coding DNA is the effect of information transfer on nucleotide composition from protein to DNA by selection according to the codon positions. Thus, coding DNA structure and ribosomal machinery co-evolved to minimize the energy cost of protein coding given the functional

  3. Phenolic Amides Are Potent Inhibitors of De Novo Nucleotide Biosynthesis.

    Science.gov (United States)

    Pisithkul, Tippapha; Jacobson, Tyler B; O'Brien, Thomas J; Stevenson, David M; Amador-Noguez, Daniel

    2015-09-01

    An outstanding challenge toward efficient production of biofuels and value-added chemicals from plant biomass is the impact that lignocellulose-derived inhibitors have on microbial fermentations. Elucidating the mechanisms that underlie their toxicity is critical for developing strategies to overcome them. Here, using Escherichia coli as a model system, we investigated the metabolic effects and toxicity mechanisms of feruloyl amide and coumaroyl amide, the predominant phenolic compounds in ammonia-pretreated biomass hydrolysates. Using metabolomics, isotope tracers, and biochemical assays, we showed that these two phenolic amides act as potent and fast-acting inhibitors of purine and pyrimidine biosynthetic pathways. Feruloyl or coumaroyl amide exposure leads to (i) a rapid buildup of 5-phosphoribosyl-1-pyrophosphate (PRPP), a key precursor in nucleotide biosynthesis, (ii) a rapid decrease in the levels of pyrimidine biosynthetic intermediates, and (iii) a long-term generalized decrease in nucleotide and deoxynucleotide levels. Tracer experiments using (13)C-labeled sugars and [(15)N]ammonia demonstrated that carbon and nitrogen fluxes into nucleotides and deoxynucleotides are inhibited by these phenolic amides. We found that these effects are mediated via direct inhibition of glutamine amidotransferases that participate in nucleotide biosynthetic pathways. In particular, feruloyl amide is a competitive inhibitor of glutamine PRPP amidotransferase (PurF), which catalyzes the first committed step in de novo purine biosynthesis. Finally, external nucleoside supplementation prevents phenolic amide-mediated growth inhibition by allowing nucleotide biosynthesis via salvage pathways. The results presented here will help in the development of strategies to overcome toxicity of phenolic compounds and facilitate engineering of more efficient microbial producers of biofuels and chemicals. Copyright © 2015, Pisithkul et al.

  4. Phenolic Amides Are Potent Inhibitors of De Novo Nucleotide Biosynthesis

    Science.gov (United States)

    Pisithkul, Tippapha; Jacobson, Tyler B.; O'Brien, Thomas J.; Stevenson, David M.

    2015-01-01

    An outstanding challenge toward efficient production of biofuels and value-added chemicals from plant biomass is the impact that lignocellulose-derived inhibitors have on microbial fermentations. Elucidating the mechanisms that underlie their toxicity is critical for developing strategies to overcome them. Here, using Escherichia coli as a model system, we investigated the metabolic effects and toxicity mechanisms of feruloyl amide and coumaroyl amide, the predominant phenolic compounds in ammonia-pretreated biomass hydrolysates. Using metabolomics, isotope tracers, and biochemical assays, we showed that these two phenolic amides act as potent and fast-acting inhibitors of purine and pyrimidine biosynthetic pathways. Feruloyl or coumaroyl amide exposure leads to (i) a rapid buildup of 5-phosphoribosyl-1-pyrophosphate (PRPP), a key precursor in nucleotide biosynthesis, (ii) a rapid decrease in the levels of pyrimidine biosynthetic intermediates, and (iii) a long-term generalized decrease in nucleotide and deoxynucleotide levels. Tracer experiments using 13C-labeled sugars and [15N]ammonia demonstrated that carbon and nitrogen fluxes into nucleotides and deoxynucleotides are inhibited by these phenolic amides. We found that these effects are mediated via direct inhibition of glutamine amidotransferases that participate in nucleotide biosynthetic pathways. In particular, feruloyl amide is a competitive inhibitor of glutamine PRPP amidotransferase (PurF), which catalyzes the first committed step in de novo purine biosynthesis. Finally, external nucleoside supplementation prevents phenolic amide-mediated growth inhibition by allowing nucleotide biosynthesis via salvage pathways. The results presented here will help in the development of strategies to overcome toxicity of phenolic compounds and facilitate engineering of more efficient microbial producers of biofuels and chemicals. PMID:26070680

  5. Purine biosynthesis de novo by lymphocytes in gout

    International Nuclear Information System (INIS)

    Kamoun, P.; Chanard, J.; Brami, M.; Funck-Brentano, J.L.

    1978-01-01

    A method of measurement in vitro of purine biosynthesis de novo in human circulating blood lymphocytes is proposed. The rate of early reactions of purine biosynthesis de novo was determined by the incorporation of [ 14 C]formate into N-formyl glycinamide ribonucleotide when the subsequent reactions of the metabolic pathway were completely inhibited by the antibiotic azaserine. Synthesis of 14 C-labelled N-formyl glycinamide ribonucleotide by lymphocytes was measured in healthy control subjects and patients with primary gout or hyperuricaemia secondary to renal failure, with or without allopurinol therapy. The average synthesis was higher in gouty patients without therapy than in control subjects, but the values contained overlap the normal range. In secondary hyperuricaemia the synthesis was at same value as in control subjects. These results are in agreement with the inconstant acceleration of purine biosynthesis de novo in gouty patients as seen by others with measurement of [ 14 C]glycine incorporation into urinary uric acid. (author)

  6. Functionalized Solid Electrodes for Electrochemical Biosensing of Purine Nucleobases and Their Analogues: A Review

    Czech Academy of Sciences Publication Activity Database

    Sharma, V.K.; Jelen, František; Trnková, L.

    2015-01-01

    Roč. 15, č. 1 (2015), s. 1564-1600 ISSN 1424-8220 Institutional support: RVO:68081707 Keywords : purine derivatives * electrochemistry of purines * carbon electrode Subject RIV: BO - Biophysics Impact factor: 2.033, year: 2015

  7. Direct N9-arylation of purines with aryl halides

    DEFF Research Database (Denmark)

    Larsen, Anders Foller; Ulven, Trond

    2014-01-01

    An efficient method for N-arylation of purines is reported. The N-arylation is catalysed by Cu(i) and 4,7-bis(2-hydroxyethylamino)-1,10-phenanthroline (BHPhen) in aqueous DMF or ethanol. The reaction generally proceeds with high selectivity for the N(9)-position.......An efficient method for N-arylation of purines is reported. The N-arylation is catalysed by Cu(i) and 4,7-bis(2-hydroxyethylamino)-1,10-phenanthroline (BHPhen) in aqueous DMF or ethanol. The reaction generally proceeds with high selectivity for the N(9)-position....

  8. Stretches of alternating pyrimidine/purines and purines are respectively linked with pathogenicity and growth temperature in prokaryotes

    DEFF Research Database (Denmark)

    Ussery, David; Bohlin, J; Hardy, SP

    2009-01-01

    BACKGROUND: The genomic fractions of purine (RR) and alternating pyrimidine/purine (YR) stretches of 10 base pairs or more, have been linked to genomic AT content, the formation of different DNA helices, strand-biased gene distribution, DNA structure, and more. Although some of these factors are ...... phyla. RR stretches are overrepresented in all phyla except for the Actinobacteria and beta-Proteobacteria. In contrast, YR tracts are underrepresented in all phyla except for the beta-Proteobacterial group. YR-stretches are associated with phylum, pathogenicity and habitat, whilst RR...

  9. Synthesis of (Purin-6-yl)methylphosphonate Bases and Nucleosides

    Czech Academy of Sciences Publication Activity Database

    Hasník, Zbyněk; Pohl, Radek; Hocek, Michal

    2010-01-01

    Roč. 51, č. 18 (2010), s. 2464-2466 ISSN 0040-4039 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : purines * nucleosides * phosphonates * cross-coupling Subject RIV: CC - Organic Chemistry Impact factor: 2.618, year: 2010

  10. Purine derivative excretion and microbial protein synthesis in sheep ...

    African Journals Online (AJOL)

    In a 3 x 3 Latin square design experiment, urinary excretions of purine derivatives (allantoin N, Uric acid N, Xanthine + Hypoxanthine N) were measured and used to estimate microbial N yield in 9 sheep fed roughage- based diet supplemented with 0, 150 and 300g DM grass silage respectively. Daily urinary excretions of ...

  11. Purines and Neuronal Excitability: Links to the Ketogenic Diet

    Science.gov (United States)

    Masino, SA; Kawamura, M; Ruskin, DN; Geiger, JD; Boison, D

    2011-01-01

    ATP and adenosine are purines that play dual roles in cell metabolism and neuronal signaling. Acting at the A1 receptor (A1R) subtype, adenosine acts directly on neurons to inhibit excitability and is a powerful endogenous neuroprotective and anticonvulsant molecule. Previous research showed an increase in ATP and other cell energy parameters when an animal is administered a ketogenic diet, an established metabolic therapy to reduce epileptic seizures, but the relationship among purines, neuronal excitability and the ketogenic diet was unclear. Recent work in vivo and in vitro tested the specific hypothesis that adenosine acting at A1Rs is a key mechanism underlying the success of ketogenic diet therapy and yielded direct evidence linking A1Rs to the antiepileptic effects of a ketogenic diet. Specifically, an in vitro mimic of a ketogenic diet revealed an A1R-dependent metabolic autocrine hyperpolarization of hippocampal neurons. In parallel, applying the ketogenic diet in vivo to transgenic mouse models with spontaneous electrographic seizures revealed that intact A1Rs are necessary for the seizure-suppressing effects of the diet. This is the first direct in vivo evidence linking A1Rs to the antiepileptic effects of a ketogenic diet. Other predictions of the relationship between purines and the ketogenic diet are discussed. Taken together, recent research on the role of purines may offer new opportunities for metabolic therapy and insight into its underlying mechanisms. PMID:21880467

  12. Molecular and biochemical characterization of caffeine synthase and purine alkaloid concentration in guarana fruit.

    Science.gov (United States)

    Schimpl, Flávia Camila; Kiyota, Eduardo; Mayer, Juliana Lischka Sampaio; Gonçalves, José Francisco de Carvalho; da Silva, José Ferreira; Mazzafera, Paulo

    2014-09-01

    Guarana seeds have the highest caffeine concentration among plants accumulating purine alkaloids, but in contrast with coffee and tea, practically nothing is known about caffeine metabolism in this Amazonian plant. In this study, the levels of purine alkaloids in tissues of five guarana cultivars were determined. Theobromine was the main alkaloid that accumulated in leaves, stems, inflorescences and pericarps of fruit, while caffeine accumulated in the seeds and reached levels from 3.3% to 5.8%. In all tissues analysed, the alkaloid concentration, whether theobromine or caffeine, was higher in young/immature tissues, then decreasing with plant development/maturation. Caffeine synthase activity was highest in seeds of immature fruit. A nucleotide sequence (PcCS) was assembled with sequences retrieved from the EST database REALGENE using sequences of caffeine synthase from coffee and tea, whose expression was also highest in seeds from immature fruit. The PcCS has 1083bp and the protein sequence has greater similarity and identity with the caffeine synthase from cocoa (BTS1) and tea (TCS1). A recombinant PcCS allowed functional characterization of the enzyme as a bifunctional CS, able to catalyse the methylation of 7-methylxanthine to theobromine (3,7-dimethylxanthine), and theobromine to caffeine (1,3,7-trimethylxanthine), respectively. Among several substrates tested, PcCS showed higher affinity for theobromine, differing from all other caffeine synthases described so far, which have higher affinity for paraxanthine. When compared to previous knowledge on the protein structure of coffee caffeine synthase, the unique substrate affinity of PcCS is probably explained by the amino acid residues found in the active site of the predicted protein. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Polymerization properties of the Thermotoga maritima actin MreB: roles of temperature, nucleotides, and ions.

    Science.gov (United States)

    Bean, Greg J; Amann, Kurt J

    2008-01-15

    MreB is a bacterial orthologue of actin that affects cell shape, polarity, and chromosome segregation. Although a significant body of work has explored its cellular functions, we know very little about the biochemical behavior of MreB. We have cloned, overexpressed in Escherichia coli, and purified untagged MreB1 from Thermotoga maritima. We have characterized the conditions that regulate its monomer-to-polymer assembly reaction, the critical concentrations of that reaction, the manner in which MreB uses nucleotides, its stability, and the structure of the assembled polymer. MreB requires a bound purine nucleotide for polymerization and rapidly hydrolyzes it following assembly. MreB assembly contains two distinct components, one that does not require divalent cations and one that does, which may comprise the nucleation and elongation phases of assembly, respectively. MreB assembly is strongly favored by increasing temperature or protein concentration but inhibited differentially by high concentrations of monovalent salts. The polymerization rate increases and the bulk critical concentration decreases with increasing temperature, but in contrast to previous reports, MreB is capable of polymerizing across a broad range of temperatures. MreB polymers are shorter and stiffer and scatter more light than eukaryotic actin filaments. Due to rapid ATP hydrolysis and phosphate release, we suggest that most assembled MreB in cells is in the ADP-bound state. Because of only moderate differences between the ATP and ADP critical concentrations, treadmilling may occur, but we do not predict dynamic instability in cells. Because of the relatively low cellular concentration of MreB and the observed structural properties of the polymer, a single MreB assembly may exist in cells.

  14. Purine biosynthesis in archaea: variations on a theme

    Directory of Open Access Journals (Sweden)

    Brown Anne M

    2011-12-01

    Full Text Available Abstract Background The ability to perform de novo biosynthesis of purines is present in organisms in all three domains of life, reflecting the essentiality of these molecules to life. Although the pathway is quite similar in eukaryotes and bacteria, the archaeal pathway is more variable. A careful manual curation of genes in this pathway demonstrates the value of manual curation in archaea, even in pathways that have been well-studied in other domains. Results We searched the Integrated Microbial Genome system (IMG for the 17 distinct genes involved in the 11 steps of de novo purine biosynthesis in 65 sequenced archaea, finding 738 predicted proteins with sequence similarity to known purine biosynthesis enzymes. Each sequence was manually inspected for the presence of active site residues and other residues known or suspected to be required for function. Many apparently purine-biosynthesizing archaea lack evidence for a single enzyme, either glycinamide ribonucleotide formyltransferase or inosine monophosphate cyclohydrolase, suggesting that there are at least two more gene variants in the purine biosynthetic pathway to discover. Variations in domain arrangement of formylglycinamidine ribonucleotide synthetase and substantial problems in aminoimidazole carboxamide ribonucleotide formyltransferase and inosine monophosphate cyclohydrolase assignments were also identified. Manual curation revealed some overly specific annotations in the IMG gene product name, with predicted proteins without essential active site residues assigned product names implying enzymatic activity (21 proteins, 2.8% of proteins inspected or Enzyme Commission (E. C. numbers (57 proteins, 7.7%. There were also 57 proteins (7.7% assigned overly generic names and 78 proteins (10.6% without E.C. numbers as part of the assigned name when a specific enzyme name and E. C. number were well-justified. Conclusions The patchy distribution of purine biosynthetic genes in archaea is

  15. Regulation of Ecto-5´-Nucleotidase by Docosahexaenoic Acid in Human Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Vu Thi Thom

    2013-08-01

    Full Text Available Background/Aims: Modulation of extracellular adenine nucleotide and adenosine concentrations is one potential mechanism by which docosahexaenoic acid (DHA may exert beneficial effects in critically ill patients. This study assessed DHA effects on extracellular adenine purines. Methods: Experiments used human pulmonary endothelial cells (HPMEC and umbilical vein endothelial cells (HUVEC treated with DHA (48 h. mRNA level (real-time PCR, expression (western blot, flow cytometry and activities (hydrolysis of etheno(ε-purines and fluorescence HPLC of CD73 (ecto-5´-nucleotidase and CD39 (ecto-NTPDase-1 were quantified. Results: DHA elevated total CD73 membrane protein expression concentration-dependently but CD73 mRNA level did not change. Increased expression was paralleled by increased enzyme activity. Effects observed on membrane level were reversed in intact cells, in which ε-AMP hydrolysis decreased after DHA. In intact endothelial cells ATP release was enhanced and CD39 activity blunted following DHA treatment. Hence, extracellular ATP and ADP concentrations increased and this inhibited ε-AMP hydrolysis. Conclusion: In human endothelial cells DHA caused 1 up-regulation of CD73 protein content and increased AMP hydrolysis at the cell membrane level, 2 increased cellular ATP release, and 3 decreased extracellular ATP/ADP hydrolysis. Thus, reorganization of the extracellular adenine-nucleotide-adenosine axis in response to DHA resulted in an increased extracellular ATP/adenosine ratio.

  16. Regulation of follitropin-sensitive adenylate cyclase by stimulatory and inhibitory forms of the guanine nucleotide regulatory protein in immature rat Sertoli cells

    International Nuclear Information System (INIS)

    Johnson, G.P.

    1987-01-01

    Studies have been designed to examine the role of guanine nucleotides in mediating FSH-sensitive adenylate cyclase activity in Sertoli cell plasma membranes. Analysis of [ 3 H]GDP binding to plasma membranes suggested a single high affinity site with a K d = 0.24 uM. Competition studies indicated that GTP γ S was 7-fold more potent than GDP β S. Bound GDP could be released by FSH in the presence of GTP γ S, but not by FSH alone. Adenylate cyclase activity was enhanced 5-fold by FSH in the presence of GTP. Addition of GDP β S to the activated enzyme (FSH plus GTP) resulted in a time-dependent decay to basal activity within 20 sec. GDP β S competitively inhibited GTP γ S-stimulated adenylate cyclase activity with a K i = 0.18 uM. Adenylate cyclase activity was also demonstrated to be sensitive to the nucleotide bound state. In the presence of FSH, only the GTP γ S-bound form persisted even if GDP β S previously occupied all available binding sites. Two membrane proteins, M r = 43,000 and 48,000, were ADP·ribosylated using cholera toxin and labeling was enhanced 2 to 4-fold by GTP γ S but not by GDP β S. The M r = 43,000 and 48,000 proteins represented variant forms of G S . A single protein of M r = 40,000 (G i ) was ADP-ribosylated by pertussis toxin in vitro. GTP inhibited forskolin-stimulated adenylate cyclase activity with an IC 50 = 0.1 uM. The adenosine analog, N 6 ·phenylisopropyl adenosine enhanced GTP inhibition of forskolin-stimulated adenylate cyclase activity by an additional 15%. GTP-dependent inhibition of forskolin-sensitive adenylate cyclase activity was abolished in membranes prepared from Sertoli cells treated in culture with pertussis toxin

  17. Metabolic Interactions of Purine Derivatives with Human ABC Transporter ABCG2: Genetic Testing to Assess Gout Risk.

    Science.gov (United States)

    Ishikawa, Toshihisa; Aw, Wanping; Kaneko, Kiyoko

    2013-11-04

    In mammals, excess purine nucleosides are removed from the body by breakdown in the liver and excretion from the kidneys. Uric acid is the end product of purine metabolism in humans. Two-thirds of uric acid in the human body is normally excreted through the kidney, whereas one-third undergoes uricolysis (decomposition of uric acid) in the gut. Elevated serum uric acid levels result in gout and could be a risk factor for cardiovascular disease and diabetes. Recent studies have shown that human ATP-binding cassette transporter ABCG2 plays a role of renal excretion of uric acid. Two non-synonymous single nucleotide polymorphisms (SNPs), i.e., 421C>A (major) and 376C>T (minor), in the ABCG2 gene result in impaired transport activity, owing to ubiquitination-mediated proteosomal degradation and truncation of ABCG2, respectively. These genetic polymorphisms are associated with hyperuricemia and gout. Allele frequencies of those SNPs are significantly higher in Asian populations than they are in African and Caucasian populations. A rapid and isothermal genotyping method has been developed to detect the SNP 421C>A, where one drop of peripheral blood is sufficient for the detection. Development of simple genotyping methods would serve to improve prevention and early therapeutic intervention for high-risk individuals in personalized healthcare.

  18. Metabolic Interactions of Purine Derivatives with Human ABC Transporter ABCG2: Genetic Testing to Assess Gout Risk

    Directory of Open Access Journals (Sweden)

    Kiyoko Kaneko

    2013-11-01

    Full Text Available In mammals, excess purine nucleosides are removed from the body by breakdown in the liver and excretion from the kidneys. Uric acid is the end product of purine metabolism in humans. Two-thirds of uric acid in the human body is normally excreted through the kidney, whereas one-third undergoes uricolysis (decomposition of uric acid in the gut. Elevated serum uric acid levels result in gout and could be a risk factor for cardiovascular disease and diabetes. Recent studies have shown that human ATP-binding cassette transporter ABCG2 plays a role of renal excretion of uric acid. Two non-synonymous single nucleotide polymorphisms (SNPs, i.e., 421C>A (major and 376C>T (minor, in the ABCG2 gene result in impaired transport activity, owing to ubiquitination-mediated proteosomal degradation and truncation of ABCG2, respectively. These genetic polymorphisms are associated with hyperuricemia and gout. Allele frequencies of those SNPs are significantly higher in Asian populations than they are in African and Caucasian populations. A rapid and isothermal genotyping method has been developed to detect the SNP 421C>A, where one drop of peripheral blood is sufficient for the detection. Development of simple genotyping methods would serve to improve prevention and early therapeutic intervention for high-risk individuals in personalized healthcare.

  19. Main: Nucleotide Analysis [KOME

    Lifescience Database Archive (English)

    Full Text Available Nucleotide Analysis Japonica genome blast search result Result of blastn search against jap...onica genome sequence kome_japonica_genome_blast_search_result.zip kome_japonica_genome_blast_search_result ...

  20. Purine analogs as phosphatidylinositol 4-kinase III beta inhibitors

    Czech Academy of Sciences Publication Activity Database

    Šála, Michal; Kögler, Martin; Plačková, Pavla; Mejdrová, Ivana; Hřebabecký, Hubert; Procházková, Eliška; Strunin, Dmytro; Lee, G.; Birkuš, G.; Weber, Jan; Mertlíková-Kaiserová, Helena; Nencka, Radim

    2016-01-01

    Roč. 26, č. 11 (2016), s. 2706-2712 ISSN 0960-894X R&D Projects: GA ČR GA15-09310S; GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : phosphatidylinositol 4-kinase * purine * PI4K III beta * antiviral agent * hepatitis C virus Subject RIV: CC - Organic Chemistry Impact factor: 2.454, year: 2016

  1. Biological treatment in clarificated purines pilot plant; Depuracion biologica en plant piloto del clarificado de los purines

    Energy Technology Data Exchange (ETDEWEB)

    Bosque Hernandez, J. L. del; Martin Sanchez, J. L. [Universidad de Salamanca (Spain)

    2004-07-01

    With the purpose of eliminating the environmental problem that suppose the residuals, denominated. Purines, it is necessary to treat them so that they can take advantage. for it, in the part I of the work, the treatment that facilitates the operation of separation of the solid in suspension of the raw purin that allows to decrease the matter organic present in the liquid phase, settled down as well as, the increase of the power fertilizer in the solid phase. The part II of this investigation have as purpose the treatment of the phase it liquidates obtained previously to adapt it for their use like water of industrial type and the solid phase as fertilizer. (Author) 5 refs.

  2. Erythrocytic Adenosine Monophosphate as an Alternative Purine Source in Plasmodium falciparum*

    Science.gov (United States)

    Cassera, María B.; Hazleton, Keith Z.; Riegelhaupt, Paul M.; Merino, Emilio F.; Luo, Minkui; Akabas, Myles H.; Schramm, Vern L.

    2008-01-01

    Plasmodium falciparum is a purine auxotroph, salvaging purines from erythrocytes for synthesis of RNA and DNA. Hypoxanthine is the key precursor for purine metabolism in Plasmodium. Inhibition of hypoxanthine-forming reactions in both erythrocytes and parasites is lethal to cultured P. falciparum. We observed that high concentrations of adenosine can rescue cultured parasites from purine nucleoside phosphorylase and adenosine deaminase blockade but not when erythrocyte adenosine kinase is also inhibited. P. falciparum lacks adenosine kinase but can salvage AMP synthesized in the erythrocyte cytoplasm to provide purines when both human and Plasmodium purine nucleoside phosphorylases and adenosine deaminases are inhibited. Transport studies in Xenopus laevis oocytes expressing the P. falciparum nucleoside transporter PfNT1 established that this transporter does not transport AMP. These metabolic patterns establish the existence of a novel nucleoside monophosphate transport pathway in P. falciparum. PMID:18799466

  3. Occurrence of theobromine synthase genes in purine alkaloid-free species of Camellia plants.

    Science.gov (United States)

    Ishida, Mariko; Kitao, Naoko; Mizuno, Kouichi; Tanikawa, Natsu; Kato, Misako

    2009-02-01

    Caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine) are purine alkaloids that are present in high concentrations in plants of some species of Camellia. However, most members of the genus Camellia contain no purine alkaloids. Tracer experiments using [8-(14)C]adenine and [8-(14)C]theobromine showed that the purine alkaloid pathway is not fully functional in leaves of purine alkaloid-free species. In five species of purine alkaloid-free Camellia plants, sufficient evidence was obtained to show the occurrence of genes that are homologous to caffeine synthase. Recombinant enzymes derived from purine alkaloid-free species showed only theobromine synthase activity. Unlike the caffeine synthase gene, these genes were expressed more strongly in mature tissue than in young tissue.

  4. Structural and catalytic effects of an invariant purine substitution in the hammerhead ribozyme: implications for the mechanism of acid–base catalysis

    Science.gov (United States)

    Schultz, Eric P.; Vasquez, Ernesto E.; Scott, William G.

    2014-01-01

    The hammerhead ribozyme catalyzes RNA cleavage via acid–base catalysis. Whether it does so by general acid–base catalysis, in which the RNA itself donates and abstracts protons in the transition state, as is typically assumed, or by specific acid–base catalysis, in which the RNA plays a structural role and proton transfer is mediated by active-site water molecules, is unknown. Previous biochemical and crystallographic experiments implicate an invariant purine in the active site, G12, as the general base. However, G12 may play a structural role consistent with specific base catalysis. To better understand the role of G12 in the mechanism of hammerhead catalysis, a 2.2 Å resolution crystal structure of a hammerhead ribozyme from Schistosoma mansoni with a purine substituted for G12 in the active site of the ribozyme was obtained. Comparison of this structure (PDB entry 3zd4), in which A12 is substituted for G, with three previously determined structures that now serve as important experimental controls, allows the identification of structural perturbations that are owing to the purine substitution itself. Kinetic measurements for G12 purine-substituted schistosomal hammerheads confirm a previously observed dependence of rate on the pK a of the substituted purine; in both cases inosine, which is similar to G in pK a and hydrogen-bonding properties, is unexpectedly inactive. Structural comparisons indicate that this may primarily be owing to the lack of the exocyclic 2-amino group in the G12A and G12I substitutions and its structural effect upon both the nucleotide base and phosphate of A9. The latter involves the perturbation of a previously identified and well characterized metal ion-binding site known to be catalytically important in both minimal and full-length hammerhead ribozyme sequences. The results permit it to be suggested that G12 plays an important role in stabilizing the active-site structure. This result, although not inconsistent with the

  5. Structural and catalytic effects of an invariant purine substitution in the hammerhead ribozyme: implications for the mechanism of acid-base catalysis.

    Science.gov (United States)

    Schultz, Eric P; Vasquez, Ernesto E; Scott, William G

    2014-09-01

    The hammerhead ribozyme catalyzes RNA cleavage via acid-base catalysis. Whether it does so by general acid-base catalysis, in which the RNA itself donates and abstracts protons in the transition state, as is typically assumed, or by specific acid-base catalysis, in which the RNA plays a structural role and proton transfer is mediated by active-site water molecules, is unknown. Previous biochemical and crystallographic experiments implicate an invariant purine in the active site, G12, as the general base. However, G12 may play a structural role consistent with specific base catalysis. To better understand the role of G12 in the mechanism of hammerhead catalysis, a 2.2 Å resolution crystal structure of a hammerhead ribozyme from Schistosoma mansoni with a purine substituted for G12 in the active site of the ribozyme was obtained. Comparison of this structure (PDB entry 3zd4), in which A12 is substituted for G, with three previously determined structures that now serve as important experimental controls, allows the identification of structural perturbations that are owing to the purine substitution itself. Kinetic measurements for G12 purine-substituted schistosomal hammerheads confirm a previously observed dependence of rate on the pK(a) of the substituted purine; in both cases inosine, which is similar to G in pK(a) and hydrogen-bonding properties, is unexpectedly inactive. Structural comparisons indicate that this may primarily be owing to the lack of the exocyclic 2-amino group in the G12A and G12I substitutions and its structural effect upon both the nucleotide base and phosphate of A9. The latter involves the perturbation of a previously identified and well characterized metal ion-binding site known to be catalytically important in both minimal and full-length hammerhead ribozyme sequences. The results permit it to be suggested that G12 plays an important role in stabilizing the active-site structure. This result, although not inconsistent with the potential

  6. T.C.G triplet in an antiparallel purine.purine.pyrimidine DNA triplex. Conformational studies by NMR.

    Science.gov (United States)

    Dittrich, K; Gu, J; Tinder, R; Hogan, M; Gao, X

    1994-04-12

    The antiparallel purine.purine.pyrimidine DNA triplex, RRY6, which contains a T.C.G inverted triplet in the center of the sequence, was examined by proton and phosphorous two-dimensional NMR spectroscopy. The local conformation of the T.C.G triplet (T4.C11.G18) and the effect of this triplet on the global helical structure were analyzed in detail. The formation of the T.C.G triplet is confirmed by a set of cross-strand NOEs, including unusual cross-strand NOEs between the third strand and the pyrimidine strand as opposed to the purine strand of the duplex. NMR data suggest that the T.C.G triplet may be present in an equilibrium between a non-hydrogen-bonded form and a T(O4)-C(NH2) hydrogen-bonded form and that there is a distortion of the in-plane alignment of the three bases. The flanking G.G.C base triplets are well-defined on the 5'-side of T4, but somewhat interrupted on the 3'-side of T4. The effect of the third strand binding on the Watson-Crick duplex was probed by an NMR study of the free duplex RY6. NMR parameters are affected mostly around the T.C.G inversion site. The perturbations extend to at least two adjacent base triplets on either side. The binding of the third purine strand and the accommodation of a central T.C.G inversion in RRY6 does not require a readjustment in sugar pucker, which remains in the range of C2'-endo. 31P resonances of RRY6 distribute over a range of 2.2 ppm. The H-P coupling patterns of the third strand differ from those of the duplex. General spectral patterns defined by the marker protons of the RRY and YRY triplexes are compared.

  7. Loss of nitric oxide-mediated inhibition of purine neurotransmitter release in the colon in the absence of interstitial cells of Cajal.

    Science.gov (United States)

    Durnin, Leonie; Lees, Andrea; Manzoor, Sheerien; Sasse, Kent C; Sanders, Kenton M; Mutafova-Yambolieva, Violeta N

    2017-11-01

    Regulation of colonic motility depends on the integrity of enteric inhibitory neurotransmission mediated by nitric oxide (NO), purine neurotransmitters, and neuropeptides. Intramuscular interstitial cells of Cajal (ICC-IM) and platelet-derived growth factor receptor-α-positive (PDGFRα + ) cells are involved in generating responses to NO and purine neurotransmitters, respectively. Previous studies have suggested a decreased nitrergic and increased purinergic neurotransmission in Kit W /Kit W-v ( W/W v ) mice that display lesions in ICC-IM along the gastrointestinal tract. However, contributions of NO to these phenotypes have not been evaluated. We used small-chamber superfusion assays and HPLC to measure the spontaneous and electrical field stimulation (EFS)-evoked release of nicotinamide adenine dinucleotide (NAD + )/ADP-ribose, uridine adenosine tetraphosphate (Up4A), adenosine 5'-triphosphate (ATP), and metabolites from the tunica muscularis of human, monkey, and murine colons and circular muscle of monkey colon, and we tested drugs that modulate NO levels or blocked NO receptors. NO inhibited EFS-evoked release of purines in the colon via presynaptic neuromodulation. Colons from W/W v , Nos1 -/- , and Prkg1 -/- mice displayed augmented neural release of purines that was likely due to altered nitrergic neuromodulation. Colons from W/W v mice demonstrated decreased nitrergic and increased purinergic relaxations in response to nerve stimulation. W/W v mouse colons demonstrated reduced Nos1 expression and reduced NO release. Our results suggest that enhanced purinergic neurotransmission may compensate for the loss of nitrergic neurotransmission in muscles with partial loss of ICC. The interactions between nitrergic and purinergic neurotransmission in the colon provide novel insight into the role of neurotransmitters and effector cells in the neural regulation of gastrointestinal motility. NEW & NOTEWORTHY This is the first study investigating the role of nitric

  8. Oligomeric interface modulation causes misregulation of purine 5'-nucleotidase in relapsed leukemia

    Czech Academy of Sciences Publication Activity Database

    Hnízda, Aleš; Škerlová, Jana; Fábry, Milan; Pachl, Petr; Šinalová, Martina; Vrzal, Lukáš; Man, Petr; Novák, Petr; Řezáčová, Pavlína; Veverka, Václav

    2016-01-01

    Roč. 14, Oct 19 (2016), č. článku 91. ISSN 1741-7007 R&D Projects: GA ČR GA15-06582S; GA MŠk(CZ) LK11205; GA MŠk(CZ) LO1304; GA MŠk LO1302; GA MŠk(CZ) LD15089; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61388963 ; RVO:68378050 ; RVO:61388971 Keywords : nucleotidase * cancer mutations * relapsed ALL * purine metabolism * allosteric regulation Subject RIV: CE - Biochemistry; EE - Microbiology, Virology (MBU-M) Impact factor: 6.779, year: 2016 http://bmcbiol.biomedcentral.com/articles/10.1186/s12915-016-0313-y

  9. Estimation of rumen microbial-nitrogen of sheep using urinary excretion of purine derivatives

    International Nuclear Information System (INIS)

    Liu Dasen; Shan Anshan

    2004-01-01

    Determination of rumen microbial-nitrogen of sheep using urinary excretion of purine derivative was studied. Uric acid and xanthine + hypoxanthine were not affected by diets, but total purine derivatives for 1 mg borax/kg diet was higher than other diets (p<0.05). Microbial-nitrogen estimated from allantoin was not affected by diets, but that of 1 mg borax/kg diet estimated from total purine derivatives was higher than other diets (p<0.05). Microbial-nitrogen estimated from total purine derivatives was higher than that from allantoin

  10. Glucagon infusion increases rate of purine synthesis de novo in rat liver

    International Nuclear Information System (INIS)

    Itakura, Mitsuo; Maeda, Noriaki; Tsuchiya, Masami; Yamashita, Kamejiro

    1987-01-01

    Based on the parallel increases of glucagon, the second peak of hepatic cAMP, and the rate of purine synthesis de novo in the prereplicative period in regenerating rate liver after a 70% hepatectomy, it was hypothesized that glucagon is responsible for the increased rate of purine synthesis de novo. To test this hypothesis, the effect of glucagon or dibutyryl cAMP infusion on the rate of purine synthesis de novo in rat liver was studied. Glucagon infusion but not insulin or glucose infusion increased the rate of purine synthesis de novo, which was assayed by [ 14 C]glycine or [ 14 C]formate incorporation, by 2.7- to 4.3-fold. Glucagon infusion increased cAMP concentrations by 4.9-fold and 5-phosphoribosyl-1-pyrophosphate concentrations by 1.5-fold in liver but did not change the specific activity of amidophosphoribosyltransferase or purine ribonucleotide concentrations. Dibutyryl cAMP infusion also increased the rate of purine synthesis de novo by 2.2- to 4.0-fold. Because glucagon infusion increased the rate of purine synthesis de novo in the presence of unchanged purine ribonucleotide concentrations, it is concluded that glucagon after infusion or in animals after a 70% hepatectomy is playing an anabolic role to increase the rate of purine synthesis de novo by increasing cAMP and 5-phosphoribosyl-1-pyrophosphate concentrations

  11. Experimental and theoretical dipole moments of purines in their ground and lowest excited singlet states

    Science.gov (United States)

    Aaron, Jean-Jacques; Diabou Gaye, Mame; Párkányi, Cyril; Cho, Nam Sook; Von Szentpály, László

    1987-01-01

    The ground-state dipole moments of seven biologically important purines (purine, 6-chloropurine, 6-mercaptopurine, hypoxanthine, theobromine, theophylline and caffeine) were determined at 25°C in acetic acid (all the above compounds with the exception of purine) and in ethyl acetate (purine, theophylline and caffeine). Because of its low solubility, it was not possible to measure the dipole moment of uric acid. The first excited singlet-state dipole moments were obtained on the basis of the Bakhshiev and Chamma—Viallet equations using the variation of the Stokes shift with the solvent dielectric constant-refractive index term. The theoretical dipole moments for all the purines listed above and including uric acid were calculated by combining the use of the PPP (π-LCI-SCF-MO) method for the π-contribution to the overall dipole moment with the σ-contribution obtained as a vector sum of the σbond moments and group moments. The experimental and theoretical values were compared with the data available in the literature for some of the purines under study. For several purines, the calculations were carried out for different tautomeric forms. Excited singlet-state dipole moments are smaller than the ground-state values by 0.8 to 2.2 Debye units for all purines under study with the exception of 6-chloropurine. The effects of the structure upon the ground- and excited-state dipole moments of the purines are discussed.

  12. Genetic Control of Biosynthesis and Transport of Riboflavin and Flavin Nucleotides and Construction of Robust Biotechnological Producers†

    Science.gov (United States)

    Abbas, Charles A.; Sibirny, Andriy A.

    2011-01-01

    Summary: Riboflavin [7,8-dimethyl-10-(1′-d-ribityl)isoalloxazine, vitamin B2] is an obligatory component of human and animal diets, as it serves as the precursor of flavin coenzymes, flavin mononucleotide, and flavin adenine dinucleotide, which are involved in oxidative metabolism and other processes. Commercially produced riboflavin is used in agriculture, medicine, and the food industry. Riboflavin synthesis starts from GTP and ribulose-5-phosphate and proceeds through pyrimidine and pteridine intermediates. Flavin nucleotides are synthesized in two consecutive reactions from riboflavin. Some microorganisms and all animal cells are capable of riboflavin uptake, whereas many microorganisms have distinct systems for riboflavin excretion to the medium. Regulation of riboflavin synthesis in bacteria occurs by repression at the transcriptional level by flavin mononucleotide, which binds to nascent noncoding mRNA and blocks further transcription (named the riboswitch). In flavinogenic molds, riboflavin overproduction starts at the stationary phase and is accompanied by derepression of enzymes involved in riboflavin synthesis, sporulation, and mycelial lysis. In flavinogenic yeasts, transcriptional repression of riboflavin synthesis is exerted by iron ions and not by flavins. The putative transcription factor encoded by SEF1 is somehow involved in this regulation. Most commercial riboflavin is currently produced or was produced earlier by microbial synthesis using special selected strains of Bacillus subtilis, Ashbya gossypii, and Candida famata. Whereas earlier RF overproducers were isolated by classical selection, current producers of riboflavin and flavin nucleotides have been developed using modern approaches of metabolic engineering that involve overexpression of structural and regulatory genes of the RF biosynthetic pathway as well as genes involved in the overproduction of the purine precursor of riboflavin, GTP. PMID:21646432

  13. Genetic control of biosynthesis and transport of riboflavin and flavin nucleotides and construction of robust biotechnological producers.

    Science.gov (United States)

    Abbas, Charles A; Sibirny, Andriy A

    2011-06-01

    Riboflavin [7,8-dimethyl-10-(1'-d-ribityl)isoalloxazine, vitamin B₂] is an obligatory component of human and animal diets, as it serves as the precursor of flavin coenzymes, flavin mononucleotide, and flavin adenine dinucleotide, which are involved in oxidative metabolism and other processes. Commercially produced riboflavin is used in agriculture, medicine, and the food industry. Riboflavin synthesis starts from GTP and ribulose-5-phosphate and proceeds through pyrimidine and pteridine intermediates. Flavin nucleotides are synthesized in two consecutive reactions from riboflavin. Some microorganisms and all animal cells are capable of riboflavin uptake, whereas many microorganisms have distinct systems for riboflavin excretion to the medium. Regulation of riboflavin synthesis in bacteria occurs by repression at the transcriptional level by flavin mononucleotide, which binds to nascent noncoding mRNA and blocks further transcription (named the riboswitch). In flavinogenic molds, riboflavin overproduction starts at the stationary phase and is accompanied by derepression of enzymes involved in riboflavin synthesis, sporulation, and mycelial lysis. In flavinogenic yeasts, transcriptional repression of riboflavin synthesis is exerted by iron ions and not by flavins. The putative transcription factor encoded by SEF1 is somehow involved in this regulation. Most commercial riboflavin is currently produced or was produced earlier by microbial synthesis using special selected strains of Bacillus subtilis, Ashbya gossypii, and Candida famata. Whereas earlier RF overproducers were isolated by classical selection, current producers of riboflavin and flavin nucleotides have been developed using modern approaches of metabolic engineering that involve overexpression of structural and regulatory genes of the RF biosynthetic pathway as well as genes involved in the overproduction of the purine precursor of riboflavin, GTP.

  14. Purine Restriction Induces Pronounced Translational Upregulation of the NT1 Adenosine/Pyrimidine Nucleoside Transporter in Leishmania major

    OpenAIRE

    Ortiz, Diana; Valdés, Raquel; Sanchez, Marco A.; Hayenga, Johanna; Elya, Carolyn; Detke, Siegfried; Landfear, Scott M.

    2010-01-01

    Leishmania and other parasitic protozoa are unable to synthesize purines de novo and are reliant upon purine nucleoside and nucleobase transporters to import preformed purines from their hosts. To study the roles of the four purine permeases NT1-NT4 in Leishmania major, null mutants in each transporter gene were prepared and the effect of each gene deletion on purine uptake was monitored. Deletion of the NT3 purine nucleobase transporter gene or both NT3 and the NT2 nucleoside transporter gen...

  15. Cyclic nucleotides and radioresistnace

    International Nuclear Information System (INIS)

    Kulinskij, V.I.; Mikheeva, G.A.; Zel'manovich, B.M.

    1982-01-01

    The addition of glucose to meat-peptone broth does not change the radiosensitizing effect (RSE) of cAMP at the logarithmic phase (LP) and the radioprotective effect (RPE) at the stationary phase (SP), but sensitization, characteristic of cGMP, disappears in SP and turns into RPE in LP. Introduction of glucose into the broth for 20 min eliminates all the effects of both cyclic nucleotides in the cya + strain while cya - mutant exhibits RSE. RSE of both cyclic nucleotides is only manifested on minimal media. These data brought confirmation of the dependence of the influence of cyclic media. These data brought confirmation of the dependence of the influence of cyclic nucleotides on radioresistance upon the metabolic status of the cell [ru

  16. Invasive Streptococcus mutans induces inflammatory cytokine production in human aortic endothelial cells via regulation of intracellular toll-like receptor 2 and nucleotide-binding oligomerization domain 2.

    Science.gov (United States)

    Nagata, E; Oho, T

    2017-04-01

    Streptococcus mutans, the primary etiologic agent of dental caries, can gain access to the bloodstream and has been associated with cardiovascular disease. However, the roles of S. mutans in inflammation in cardiovascular disease remain unclear. The aim of this study was to examine cytokine production induced by S. mutans in human aortic endothelial cells (HAECs) and to evaluate the participation of toll-like receptors (TLRs) and cytoplasmic nucleotide-binding oligomerization domain (NOD) -like receptors in HAECs. Cytokine production by HAECs was determined using enzyme-linked immunosorbent assays, and the expression of TLRs and NOD-like receptors was evaluated by real-time polymerase chain reaction, flow cytometry and immunocytochemistry. The involvement of TLR2 and NOD2 in cytokine production by invaded HAECs was examined using RNA interference. The invasion efficiencies of S. mutans strains were evaluated by means of antibiotic protection assays. Five of six strains of S. mutans of various serotypes induced interleukin-6, interleukin-8 and monocyte chemoattractant protein-1 production by HAECs. All S. mutans strains upregulated TLR2 and NOD2 mRNA levels in HAECs. Streptococcus mutans Xc upregulated the intracellular TLR2 and NOD2 protein levels in HAECs. Silencing of the TLR2 and NOD2 genes in HAECs invaded by S. mutans Xc led to a reduction in interleukin-6, interleukin-8 and monocyte chemoattractant protein-1 production. Cytokine production induced by invasive S. mutans via intracellular TLR2 and NOD2 in HAECs may be associated with inflammation in cardiovascular disease. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Single Nucleotide Polymorphisms in Regulator-Encoding Genes Have an Additive Effect on Virulence Gene Expression in a Vibrio cholerae Clinical Isolate.

    Science.gov (United States)

    Carignan, Bailey M; Brumfield, Kyle D; Son, Mike S

    2016-01-01

    Vibrio cholerae is the etiological agent of the infectious disease cholera, which is characterized by vomiting and severe watery diarrhea. Recently, V. cholerae clinical isolates have demonstrated increased virulence capabilities, causing more severe symptoms with a much higher rate of disease progression than previously observed. We have identified single nucleotide polymorphisms (SNPs) in four virulence-regulatory genes (hapR, hns, luxO, and vieA) of a hypervirulent V. cholerae clinical isolate, MQ1795. Herein, all SNPs and SNP combinations of interest were introduced into the prototypical El Tor reference strain N16961, and the effects on the production of numerous virulence-related factors, including cholera toxin (CT), the toxin-coregulated pilus (TCP), and ToxT, were analyzed. Our data show that triple-SNP (hapR hns luxO and hns luxO vieA) and quadruple-SNP combinations produced the greatest increases in CT, TCP, and ToxT production. The hns and hns luxO SNP combinations were sufficient for increased TCP and ToxT production. Notably, the hns luxO vieA triple-SNP combination strain produced TCP and ToxT levels similar to those of MQ1795. Certain SNP combinations (hapR and hapR vieA) had the opposite effect on CT, TCP, and ToxT expression. Interestingly, the hns vieA double-SNP combination strain increased TCP production while decreasing CT production. Our findings suggest that SNPs identified in the four regulatory genes, in various combinations, are associated with increased virulence capabilities observed in V. cholerae clinical isolates. These studies provide insight into the evolution of highly virulent strains. IMPORTANCE Cholera, an infectious disease of the small intestine caused by the aquatic bacterium Vibrio cholerae, often results in vomiting and acute watery diarrhea. If left untreated or if the response is too slow, the symptoms can quickly lead to extreme dehydration and ultimately death of the patient. Recent anecdotal evidence of cholera

  18. Gene set analysis of purine and pyrimidine antimetabolites cancer therapies.

    Science.gov (United States)

    Fridley, Brooke L; Batzler, Anthony; Li, Liang; Li, Fang; Matimba, Alice; Jenkins, Gregory D; Ji, Yuan; Wang, Liewei; Weinshilboum, Richard M

    2011-11-01

    Responses to therapies, either with regard to toxicities or efficacy, are expected to involve complex relationships of gene products within the same molecular pathway or functional gene set. Therefore, pathways or gene sets, as opposed to single genes, may better reflect the true underlying biology and may be more appropriate units for analysis of pharmacogenomic studies. Application of such methods to pharmacogenomic studies may enable the detection of more subtle effects of multiple genes in the same pathway that may be missed by assessing each gene individually. A gene set analysis of 3821 gene sets is presented assessing the association between basal messenger RNA expression and drug cytotoxicity using ethnically defined human lymphoblastoid cell lines for two classes of drugs: pyrimidines [gemcitabine (dFdC) and arabinoside] and purines [6-thioguanine and 6-mercaptopurine]. The gene set nucleoside-diphosphatase activity was found to be significantly associated with both dFdC and arabinoside, whereas gene set γ-aminobutyric acid catabolic process was associated with dFdC and 6-thioguanine. These gene sets were significantly associated with the phenotype even after adjusting for multiple testing. In addition, five associated gene sets were found in common between the pyrimidines and two gene sets for the purines (3',5'-cyclic-AMP phosphodiesterase activity and γ-aminobutyric acid catabolic process) with a P value of less than 0.0001. Functional validation was attempted with four genes each in gene sets for thiopurine and pyrimidine antimetabolites. All four genes selected from the pyrimidine gene sets (PSME3, CANT1, ENTPD6, ADRM1) were validated, but only one (PDE4D) was validated for the thiopurine gene sets. In summary, results from the gene set analysis of pyrimidine and purine therapies, used often in the treatment of various cancers, provide novel insight into the relationship between genomic variation and drug response.

  19. 9-Benzyl-6-benzylsulfanyl-9H-purin-2-amine

    Directory of Open Access Journals (Sweden)

    Maywan Hariono

    2014-03-01

    Full Text Available In the title compound, C19H17N5S, the dihedral angles between the purine ring system (r.m.s. deviation = 0.009 Å and the S-bound and methylene-bound phenyl rings are 74.67 (8 and 71.28 (7°, respectively. In the crystal, inversion dimers linked by pairs of N—H...N hydrogen bonds generate R22(8 loops. C—H...N interactions link the dimers into (100 sheets.

  20. Purine nucleoside phosphorylase deficiency in two unrelated Saudi patients

    International Nuclear Information System (INIS)

    Alangari, Abdullah; AlHarbi, Abdullah; AlGhonaium Abdulaziz; Santisteban, Ines; Hershfield, Michael

    2009-01-01

    Purine nucleoside phosphorylase (PNP) deficiency is a rare autosomal recessive metabolic disorder that results in combined immunodeficiency, neurologic dysfunction and autoimmunity. PNP deficiency has never been reported from Saudi Arabia or in patients with an Arabic ethnic background. We report on two Saudi girls with PNP deficiency. Both showed severe lymphopenia and neurological involvement. Sequencing of the PNP gene of one girl revealed a novel missense mutation Pro146>Leu in exon 4 due to a change in the codon from CCT>CTT. Expression of PNP (146L) cDNA in E coli indicated that the mutation greatly reduced, but did not completely eliminate PNP activity. (author)

  1. Modification of nucleotide metabolism in relationship with differentiation and in response to irradiation in human tumour cells

    International Nuclear Information System (INIS)

    Wei, Shuang

    1998-01-01

    This research thesis reports the study of the metabolism of nucleotides in human tumour cells. The first part addresses the modifications of nucleotide (more specifically purine) metabolism in relationship with human melanoma cell proliferation and differentiation. The second part addresses the modifications of this metabolism in response to an irradiation in human colon tumour cells. For each part, the author proposes a bibliographic synthesis, and a presentation of studied cells and of methods used to grow cells, and respectively to proliferate and differentiate them or to irradiate them, and then discusses the obtained results [fr

  2. Two purine nucleoside phosphorylases in Bacillus subtilis. Purification and some properties of the adenosine-specific phosphorylase

    DEFF Research Database (Denmark)

    Jensen, Kaj Frank

    1978-01-01

    Two purine nucleoside phosphorylases (purine-nucleoside:orthophosphate ribosyltransferase, EC 2.4.2.1) were purified from vegetative Bacillus subtilis cells. One enzyme, inosine-guanosine phosphorylase, showed great similarity to the homologous enzyme of Bacillus cereus. It appeared...

  3. Purine Bases in Blood Plasma of Patients with Chronic Pulmonary Diseases

    Directory of Open Access Journals (Sweden)

    Larissa E. Muravluyova

    2012-09-01

    Full Text Available The article is focused on the study of purine bases and intermediates of purine catabolism in plasma of patients with chronic obstructive bronchitis and idiopathic interstitial pneumonia. Decrease of adenine and hypoxantine in plasma of patients with idiopathic interstitial pneumonia was registered. Increase of guanine in plasma of patients with chronic obstructive pulmonary disease was established.

  4. Purine derivate content and amino acid profile in larval stages of three edible insects.

    Science.gov (United States)

    Bednářová, Martina; Borkovcová, Marie; Komprda, Tomáš

    2014-01-15

    Considering their high content of protein, insects are a valuable alternative protein source. However, no evaluation of their purine content has so far been done. High content of purine derivates may lead to the exclusion of such food from the diet of people with specific diseases. The aim of this study was to analyse the content of selected purine derivates and amino acid profile in the three insect species most often used for entomophagy in Europe and compare them with the purine content in egg white and chicken breast. The content of individual purine derivates and their total content were significantly dependent on insect species. The purine content in all three species was significantly higher (P < 0.05) than in egg white, but some values were significantly lower (P < 0.05) than in chicken breast. The total protein content was 548.9 g kg(-1) dry matter (DM) in mealworm (Tenebrio molitor), 551.6 g kg(-1) DM in superworm (Zophobas atratus) and 564.9 g kg(-1) DM in cricket (Gryllus assimilis). Larvae of mealworm and superworm are protein-rich and purine-low meat alternatives. In contrast, cricket nymphs are protein-rich and purine-rich and cannot be recommended for people with hyperuricemia or gout. © 2013 Society of Chemical Industry.

  5. MUTATIONAL SYNERGISM BETWEEN RADIATIONS AND METHYLATED PURINES IN ESCHERICHIA COLI

    Science.gov (United States)

    Doneson, Ira N.; Shankel, Delbert M.

    1964-01-01

    Doneson, Ira N. (University of Kansas, Lawrence), and Delbert M. Shankel. Mutational synergism between radiations and methylalted purines in Escherichia coli. J. Bacteriol. 87:61–67. 1964.—A synergistic mutational effect was demonstrated between low doses of ultraviolet light and the methylated purines caffeine, theophylline, and theobromine. Caffeine produced the greatest effect and theobromine the least effect. The magnitude of the synergism was inversely related to the ultraviolet dosage. A large percentage of the synergistic effect could be “photoprevented” by exposure of the ultraviolet-treated cells to white light prior to exposure to the analogues. The consequence of the combined treatment occurred only when the chemical treatment followed the ultraviolet treatment. Furthermore, it was necessary to administer the chemical treatment soon after the ultraviolet treatment or the mutants were “lost.” When cells were treated with low dosages of ultraviolet light and of X irradiation (X ray), the result was merely additive, and combinations of X ray and chemical treatment yielded no synergism. Synchronous growth studies indicated that a particular growth stage of the organisms was most susceptible to the synergistic effect. The mutation studied was that of Escherichia coli B/r to high-level streptomycin resistance. PMID:14102875

  6. Single Nucleotide Polymorphism

    DEFF Research Database (Denmark)

    Børsting, Claus; Pereira, Vania; Andersen, Jeppe Dyrberg

    2014-01-01

    Single nucleotide polymorphisms (SNPs) are the most frequent DNA sequence variations in the genome. They have been studied extensively in the last decade with various purposes in mind. In this chapter, we will discuss the advantages and disadvantages of using SNPs for human identification...... of SNPs. This will allow acquisition of more information from the sample materials and open up for new possibilities as well as new challenges....

  7. The arabidopsis cyclic nucleotide interactome

    KAUST Repository

    Donaldson, Lara Elizabeth; Meier, Stuart Kurt; Gehring, Christoph A

    2016-01-01

    Cyclic nucleotides have been shown to play important signaling roles in many physiological processes in plants including photosynthesis and defence. Despite this, little is known about cyclic nucleotide-dependent signaling mechanisms

  8. Regulation of bovine kidney alpha-ketoglutarate dehydrogenase complex by calcium ion and adenine nucleotides. Effects on S0.5 for alpha-ketoglutarate.

    Science.gov (United States)

    Lawlis, V B; Roche, T E

    1981-04-28

    Regulation of bovine kidney alpha-ketoglutarate dehydrogenase complex by energy-linked metabolites was investigated. Ca2+, ADP, or inorganic phosphate markedly enhanced the activity of the complex, and ATP or, to a lesser extent, GTP decreased the activity of the complex. Initial velocity studies with alpha-ketoglutarate as the varied substrate demonstrated that these modulators induced large changes in S0.5 for alpha-ketoglutarate (based on analysis in Hill plots) with no change in the maximum velocity (as determined by double-reciprocal plots). For all conditions studied, the Hill coefficients were significantly less than 1.0 with slopes that were linear over wide ranges of alpha-ketoglutarate concentrations, indicating negative cooperativity that probably resulted from multiple site-site interactions. Ca2+ (maintained at 10 muM by a Ca2+ buffer) decreased the S0.5 for alpha-ketoglutarate 63-fold (from 25 to 0.40 mM); even in the presence of a positive effector, ADP or phosphate, Ca2+ decreased the S0.5 for alpha-ketoglutarate 7.8- or 28-fold, respectively. Consistent with a mechanism of action dependent of Ca2+, ADP (1.60 mM) or phosphate (20 mM) reduced the S0.5 for alpha-ketoglutarate in the presence of Ca2+ (i.e., 4.5- or 1.67-fold, respectively); however, these effectors elicited larger decreases in S0.5 in the absence of Ca2+ (i.e., 37- or 3.7-fold, respectively). ATP (1.6 mM) increased the S0.5 for alpha-ketoglutarate, and Ca2+ appreciably reduced the effect, lowering the S0.5 98-fold from 66 to 0.67 mM. Thus the activity of the kidney alpha-ketoglutarate dehydrogenase complex is poised to increase as the energy potential in mitochondria declines, and Ca2+ has a pronounced modulatory effect. Comparative studies on bovine heart alpha-ketoglutarate dehydrogenase complex and the effects of varying the ADP/ATP ratio in the presence or absence of Ca2+ or phosphate are also described.

  9. Anopheles gambiae Purine Nucleoside Phosphorylase: Catalysis, Structure, and Inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Taylor,E.; Rinaldo-Matthis, A.; Li, L.; Ghanem, M.; Hazleton, K.; Cassera, M.; Almo, S.; Schramm, V.

    2007-01-01

    The purine salvage pathway of Anopheles gambiae, a mosquito that transmits malaria, has been identified in genome searches on the basis of sequence homology with characterized enzymes. Purine nucleoside phosphorylase (PNP) is a target for the development of therapeutic agents in humans and purine auxotrophs, including malarial parasites. The PNP from Anopheles gambiae (AgPNP) was expressed in Escherichia coli and compared to the PNPs from Homo sapiens (HsPNP) and Plasmodium falciparum (PfPNP). AgPNP has kcat values of 54 and 41 s-1 for 2'-deoxyinosine and inosine, its preferred substrates, and 1.0 s-1 for guanosine. However, the chemical step is fast for AgPNP at 226 s-1 for guanosine in pre-steady-state studies. 5'-Deaza-1'-aza-2'-deoxy-1'-(9-methylene)-Immucillin-H (DADMe-ImmH) is a transition-state mimic for a 2'-deoxyinosine ribocation with a fully dissociated N-ribosidic bond and is a slow-onset, tight-binding inhibitor with a dissociation constant of 3.5 pM. This is the tightest-binding inhibitor known for any PNP, with a remarkable Km/Ki* of 5.4 x 107, and is consistent with enzymatic transition state predictions of enhanced transition-state analogue binding in enzymes with enhanced catalytic efficiency. Deoxyguanosine is a weaker substrate than deoxyinosine, and DADMe-Immucillin-G is less tightly bound than DADMe-ImmH, with a dissociation constant of 23 pM for AgPNP as compared to 7 pM for HsPNP. The crystal structure of AgPNP was determined in complex with DADMe-ImmH and phosphate to a resolution of 2.2 Angstroms to reveal the differences in substrate and inhibitor specificity. The distance from the N1' cation to the phosphate O4 anion is shorter in the AgPNP{center_dot}DADMe-ImmH{center_dot}PO4 complex than in HsPNP{center_dot}DADMe-ImmH{center_dot}SO4, offering one explanation for the stronger inhibitory effect of DADMe-ImmH for AgPNP.

  10. Purine biosynthesis is the bottleneck in trimethoprim-treated Bacillus subtilis.

    Science.gov (United States)

    Stepanek, Jennifer Janina; Schäkermann, Sina; Wenzel, Michaela; Prochnow, Pascal; Bandow, Julia Elisabeth

    2016-10-01

    Trimethoprim is a folate biosynthesis inhibitor. Tetrahydrofolates are essential for the transfer of C 1 units in several biochemical pathways including purine, thymine, methionine, and glycine biosynthesis. This study addressed the effects of folate biosynthesis inhibition on bacterial physiology. Two complementary proteomic approaches were employed to analyze the response of Bacillus subtilis to trimethoprim. Acute changes in protein synthesis rates were monitored by radioactive pulse labeling of newly synthesized proteins and subsequent 2DE analysis. Changes in protein levels were detected using gel-free quantitative MS. Proteins involved in purine and histidine biosynthesis, the σ B -dependent general stress response, and sporulation were upregulated. Most prominently, the PurR-regulon required for de novo purine biosynthesis was derepressed indicating purine depletion. The general stress response was activated energy dependently and in a subpopulation of treated cultures an early onset of sporulation was observed, most likely triggered by low guanosine triphosphate levels. Supplementation of adenosine triphosphate, adenosine, and guanosine to the medium substantially decreased antibacterial activity, showing that purine depletion becomes the bottleneck in trimethoprim-treated B. subtilis. The frequently prescribed antibiotic trimethoprim causes purine depletion in B. subtilis, which can be complemented by supplementing purines to the medium. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Purine Turnover Metabolites and Selected Antioxidants in Blood of Goats during the Periparturient Period

    Directory of Open Access Journals (Sweden)

    Ewa Skotnicka

    2010-01-01

    Full Text Available The aim of this study was to examine the relationships between the erythrocyte concentrations of ATP, ADP, AMP, NAD+, NADP+ and adenylate energy charge (AEC and their metabolites: inosine (Ino, hypoxanthine (Hyp, uric acid (UA, selected blood antioxidants: superoxide dismutase (SOD, glutathione reductase (GR of goats during the periparturient period. The study was conducted on 12 clinically healthy pregnant goats (Capra hircus - 75% genotype of the Polish noble white aged between 2-3 years. Blood was taken from the external jugular vein early in the morning before feeding and obtained twice (4 weeks and 1 week before delivery and twice (2 and 3 weeks after delivery. The ATP concentration did not change significantly. One week before delivery ADP, AMP and Ino concentrations were significantly higher and AEC value significantly lower compared to values in the third week after delivery (p ≤ 0.02, p ≤ 0.05, p ≤ 0.03 and p ≤ 0.01, respectively. One week before and two weeks after delivery we observed a significant increase in SOD and GR activities and an increase in NAD+ and NADP+ concentrations but a significant decrease in Hyp and UA concentrations. Constant ATP concentration and the changes in the dynamics and tendency of Hyp and UA concentrations show that in the periparturient period in goats, purine metabolism undergoes adaptive changes. The balance between resynthetic processes and adenine nucleotide degradation is retained in order to level the oxygen and energy lacks. The results of our study show that the maintenance of prooxidative homeostasis in goats of peripartal period depends mainly on enzymatic mechanisms.

  12. Purine receptor P2Y_6 mediates cellular response to γ-ray-induced DNA damage

    International Nuclear Information System (INIS)

    Ide, Shunta; Nishimaki, Naoko; Tsukimoto, Mitsutoshi; Kojima, Shuji

    2014-01-01

    We previously showed that nucleotide P2 receptor agonists such as ATP and UTP amplify γ-ray-induced focus formation of phosphorylated histone H2A variant H2AX (γH2AX), which is considered to be an indicator of DNA damage so far, by activating purine P2Y_6 and P2Y_1_2 receptors. Therefore, we hypothesized that these P2 receptors play a role in inducing the repair response to γ-ray-induced DNA damage. In the present study, we tested this idea by using human lung cancer A549 cells. First, reverse-transcription polymerase chain reaction (RT-PCR) showed that P2Y_6 receptor is highly expressed in A549 cells, but P2Y_1_2 receptor is only weakly expressed. Next, colony formation assay revealed that P2Y_6 receptor antagonist MRS2578 markedly reduced the survival rate of γ-ray-exposed A549 cells. The survival rate was also significantly reduced in P2Y_6-knock-down cells, compared with scramble siRNA-transfected cells. Since it has reported that phosphorylation of ERK1/2 after activation of EGFR via P2Y_6 and P2Y_1_2 receptors is involved in the repair response to γ-ray-induced DNA damage, we next examined whether γ-ray-induced phosphorylation of ERK1/2 was also inhibited by MRS2578 in A549 cells. We found that it was. Taken together, these findings indicate that purinergic signaling through P2Y_6 receptor, followed by ERK1/2 activation, promotes the cellular repair response to γ-ray-induced DNA damage. (author)

  13. Using purine skews to predict genes in AT-rich poxviruses

    Directory of Open Access Journals (Sweden)

    Upton Chris

    2005-02-01

    Full Text Available Abstract Background Clusters or runs of purines on the mRNA synonymous strand have been found in many different organisms including orthopoxviruses. The purine bias that is exhibited by these clusters can be observed using a purine skew and in the case of poxviruses, these skews can be used to help determine the coding strand of a particular segment of the genome. Combined with previous findings that minor ORFs have lower than average aspartate and glutamate composition and higher than average serine composition, purine content can be used to predict the likelihood of a poxvirus ORF being a "real gene". Results Using purine skews and a "quality" measure designed to incorporate previous findings about minor ORFs, we have found that in our training case (vaccinia virus strain Copenhagen, 59 of 65 minor (small and unlikely to be a real genes ORFs were correctly classified as being minor. Of the 201 major (large and likely to be real genes vaccinia ORFs, 192 were correctly classified as being major. Performing a similar analysis with the entomopoxvirus amsacta moorei (AMEV, it was found that 4 major ORFs were incorrectly classified as minor and 9 minor ORFs were incorrectly classified as major. The purine abundance observed for major ORFs in vaccinia virus was found to stem primarily from the first codon position with both the second and third codon positions containing roughly equal amounts of purines and pyrimidines. Conclusion Purine skews and a "quality" measure can be used to predict functional ORFs and purine skews in particular can be used to determine which of two overlapping ORFs is most likely to be the real gene if neither of the two ORFs has orthologs in other poxviruses.

  14. Inhibition of DNA glycosylases via small molecule purine analogs.

    Directory of Open Access Journals (Sweden)

    Aaron C Jacobs

    Full Text Available Following the formation of oxidatively-induced DNA damage, several DNA glycosylases are required to initiate repair of the base lesions that are formed. Recently, NEIL1 and other DNA glycosylases, including OGG1 and NTH1 were identified as potential targets in combination chemotherapeutic strategies. The potential therapeutic benefit for the inhibition of DNA glycosylases was validated by demonstrating synthetic lethality with drugs that are commonly used to limit DNA replication through dNTP pool depletion via inhibition of thymidylate synthetase and dihydrofolate reductase. Additionally, NEIL1-associated synthetic lethality has been achieved in combination with Fanconi anemia, group G. As a prelude to the development of strategies to exploit the potential benefits of DNA glycosylase inhibition, it was necessary to develop a reliable high-throughput screening protocol for this class of enzymes. Using NEIL1 as the proof-of-principle glycosylase, a fluorescence-based assay was developed that utilizes incision of site-specifically modified oligodeoxynucleotides to detect enzymatic activity. This assay was miniaturized to a 1536-well format and used to screen small molecule libraries for inhibitors of the combined glycosylase/AP lyase activities. Among the top hits of these screens were several purine analogs, whose postulated presence in the active site of NEIL1 was consistent with the paradigm of NEIL1 recognition and excision of damaged purines. Although a subset of these small molecules could inhibit other DNA glycosylases that excise oxidatively-induced DNA adducts, they could not inhibit a pyrimidine dimer-specific glycosylase.

  15. Isolation and characterization of human glycophorin A cDNAs using a synthetic oligonucleotide approach: nucleotide sequence, mRNA structure and regulation by 12-O-tetradecanoylphorbol 13-acetate (TPA)

    International Nuclear Information System (INIS)

    Siebert, P.D.; Fukuda, M.

    1986-01-01

    The authors have previously shown that treatment of human erythroleukemic K562 cells with the tumor-promoting phorbol ester, TPA, results in a diminished expression of glycophorin A at the level of protein biosynthesis and in vitro mRNA translation activity. To further examine the structure, relationships and expression of human glycophorins they have successfully isolated and sequenced several glycophorin A specific cDNA clones derived from K562 cells, by making extensive use of mixed and exact synthetic oligonucleotides as primers and radioactively labeled probes. The nucleotide sequence obtained from the largest glycophorin A cDNA suggests the presence of a hydrophobic leader-like peptide of at least 19 amino acids. Northern gel analysis using both whole cDNA-plasmid and synthetic oligonucleotide probes revealed the existence of multiple mRNAs, three of which they believe to be glycophorin A-specific, whereas a fourth and smaller mRNA appears to be glycophorin B-specific. Furthermore, the abundance of all four glycophorin mRNAs were found to be extensively reduced following treatment of K562 cells with TPA suggesting coordinate regulation, possibly at the level of gene transcription

  16. Nucleotides and regulation of bone cell function

    National Research Council Canada - National Science Library

    Burnstock, Geoffrey; Arnett, Timothy R

    2007-01-01

    ...) International Standard Book Number-13: 978-0-8493-3368-2 (Hardcover) This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permis...

  17. Versatile synthesis and biological evaluation of novel 3’-fluorinated purine nucleosides

    Directory of Open Access Journals (Sweden)

    Hang Ren

    2015-12-01

    Full Text Available A unified synthetic strategy accessing novel 3'-fluorinated purine nucleoside derivatives and their biological evaluation were achieved. Novel 3’-fluorinated analogues were constructed from a common 3’-deoxy-3’-fluororibofuranose intermediate. Employing Suzuki and Stille cross-coupling reactions, fifteen 3’-fluororibose purine nucleosides 1–15 and eight 3’-fluororibose 2-chloro/2-aminopurine nucleosides 16–23 with various substituents at position 6 of the purine ring were efficiently synthesized. Furthermore, 3’-fluorine analogs of natural products nebularine and 6-methylpurine riboside were constructed via our convergent synthetic strategy. Synthesized nucleosides were tested against HT116 (colon cancer and 143B (osteosarcoma cancer tumor cell lines. We have demonstrated 3’-fluorine purine nucleoside analogues display potent tumor cell growth inhibition activity at sub- or low micromolar concentration.

  18. The Purine-Utilizing Bacterium Clostridium acidurici 9a: A Genome-Guided Metabolic Reconsideration

    OpenAIRE

    Hartwich, Katrin; Poehlein, Anja; Daniel, Rolf

    2012-01-01

    Clostridium acidurici is an anaerobic, homoacetogenic bacterium, which is able to use purines such as uric acid as sole carbon, nitrogen, and energy source. Together with the two other known purinolytic clostridia C. cylindrosporum and C. purinilyticum, C. acidurici serves as a model organism for investigation of purine fermentation. Here, we present the first complete sequence and analysis of a genome derived from a purinolytic Clostridium. The genome of C. acidurici 9a consists ...

  19. Role of Metal Oxides in Chemical Evolution: Interaction of Ribose Nucleotides with Alumina

    Science.gov (United States)

    Arora, Avnish Kumar; Kamaluddin

    2009-03-01

    Interaction of ribonucleotides—namely, 5‧-AMP, 5‧-GMP, 5‧-CMP, and 5‧-UMP—with acidic, neutral, and basic alumina has been studied. Purine nucleotides showed higher adsorption on alumina in comparison with pyrimidine nucleotides under acidic conditions. Adsorption data obtained followed Langmuir adsorption isotherm, and Xm and KL values were calculated. On the basis of infrared spectral studies of ribonucleotides, alumina, and ribonucleotide-alumina adducts, we propose that the nitrogen base and phosphate moiety of the ribonucleotides interact with the positive charge surface of alumina. Results of the present study may indicate the importance of alumina in concentrating organic molecules from dilute aqueous solutions in primeval seas in the course of chemical evolution on Earth.

  20. Functional and Structural Characterization of Purine Nucleoside Phosphorylase from Kluyveromyces lactis and Its Potential Applications in Reducing Purine Content in Food.

    Science.gov (United States)

    Mahor, Durga; Priyanka, Anu; Prasad, Gandham S; Thakur, Krishan Gopal

    2016-01-01

    Consumption of foods and beverages with high purine content increases the risk of hyperuricemia, which causes gout and can lead to cardiovascular, renal, and other metabolic disorders. As patients often find dietary restrictions challenging, enzymatically lowering purine content in popular foods and beverages offers a safe and attractive strategy to control hyperuricemia. Here, we report structurally and functionally characterized purine nucleoside phosphorylase (PNP) from Kluyveromyces lactis (KlacPNP), a key enzyme involved in the purine degradation pathway. We report a 1.97 Å resolution crystal structure of homotrimeric KlacPNP with an intrinsically bound hypoxanthine in the active site. KlacPNP belongs to the nucleoside phosphorylase-I (NP-I) family, and it specifically utilizes 6-oxopurine substrates in the following order: inosine > guanosine > xanthosine, but is inactive towards adenosine. To engineer enzymes with broad substrate specificity, we created two point variants, KlacPNPN256D and KlacPNPN256E, by replacing the catalytically active Asn256 with Asp and Glu, respectively, based on structural and comparative sequence analysis. KlacPNPN256D not only displayed broad substrate specificity by utilizing both 6-oxopurines and 6-aminopurines in the order adenosine > inosine > xanthosine > guanosine, but also displayed reversal of substrate specificity. In contrast, KlacPNPN256E was highly specific to inosine and could not utilize other tested substrates. Beer consumption is associated with increased risk of developing gout, owing to its high purine content. Here, we demonstrate that KlacPNP and KlacPNPN256D could be used to catalyze a key reaction involved in lowering beer purine content. Biochemical properties of these enzymes such as activity across a wide pH range, optimum activity at about 25°C, and stability for months at about 8°C, make them suitable candidates for food and beverage industries. Since KlacPNPN256D has broad substrate specificity, a

  1. Purine-Metabolizing Ectoenzymes Control IL-8 Production in Human Colon HT-29 Cells

    Directory of Open Access Journals (Sweden)

    Fariborz Bahrami

    2014-01-01

    Full Text Available Interleukin-8 (IL-8 plays key roles in both chronic inflammatory diseases and tumor modulation. We previously observed that IL-8 secretion and function can be modulated by nucleotide (P2 receptors. Here we investigated whether IL-8 release by intestinal epithelial HT-29 cells, a cancer cell line, is modulated by extracellular nucleotide metabolism. We first identified that HT-29 cells regulated adenosine and adenine nucleotide concentration at their surface by the expression of the ectoenzymes NTPDase2, ecto-5′-nucleotidase, and adenylate kinase. The expression of the ectoenzymes was evaluated by RT-PCR, qPCR, and immunoblotting, and their activity was analyzed by RP-HPLC of the products and by detection of Pi produced from the hydrolysis of ATP, ADP, and AMP. In response to poly (I:C, with or without ATP and/or ADP, HT-29 cells released IL-8 and this secretion was modulated by the presence of NTPDase2 and adenylate kinase. Taken together, these results demonstrate the presence of 3 ectoenzymes at the surface of HT-29 cells that control nucleotide levels and adenosine production (NTPDase2, ecto-5′-nucleotidase and adenylate kinase and that P2 receptor-mediated signaling controls IL-8 release in HT-29 cells which is modulated by the presence of NTPDase2 and adenylate kinase.

  2. Pertumbuhan Plantlet Anggrek Cattleya sp. dengan Perlakuan Benzyl Amino Purine pada Media Dasar Pupuk Daun Modifikasi

    Directory of Open Access Journals (Sweden)

    HESTIN YUSWANTI

    2015-09-01

    Full Text Available Growth of Plantlets of Cattleya Orchid on The Fooliar Fertilizer-Based Medium added with Benzyl Amino Purine. The aim of the current research was to investigate the appropriate concentrationof plant growth regulator BAP on the growth of Cattleya plantlet. The experiment was utilized a Randomized Completely Design with five treatments and six replications. The basal medium used was modification of foliar fertilizer of Growmore (trade mark with addition of fish emulsion, Vitamin B1 and active charcoal. BAP concentration used as treatment were 0 ppm, 0.5 ppm, 1.0 ppm, 1.5 ppm and 2.0 ppm. Variables observed were height, leaf number, root number, root length, fresh weight and dry weight of plantlets. The result showed that concentration of 1 ppm BAP resulted in the highest value for plantlet height (5.67 cm, leaf number (4.67, root length (2.07 cm, fresh weight (0.36 g and dry weight (0.043 g.

  3. Design, Synthesis and Antiviral Activity of 5-Hydroxymethyl-3-phosphonyl-4,5-dihydrofuran Analogs of Nucleotides

    International Nuclear Information System (INIS)

    Lee, Hee Yoon; Lee, Ki Ho; Hah, Jung Hwan; Moon, Deuk Kyu; Lee, Chong Kyo

    2010-01-01

    We have designed and synthesized functionalized dihydrofurylphosphonates that are constrained analogs of 1-alkenyl-phosphonate derivatives of purine/pyrimidine nucleotides as they bear phosphonyl groups at the 3-position and bases at the methyl group of the 5-position of the furan ring. This newly designed dihydrofurylphosphonate analogs of nucleotide showed antiviral activity. Through the current synthetic strategy, structural diversification can be easily attainable for structure activity relationship study and for the better antiviral compounds. Phosphonate esters play an important role in studying the biological system as a hydrolytically stable replacement of phosphate groups and as prodrugs of phosphonates. In continuation of our study on the chemistry of 1-alkenylphosphonates, we were interested in designing and developing versatile synthetic routes to conformationally constrained structures of al-kenylphosphonate nucleotide analogs

  4. The arabidopsis cyclic nucleotide interactome

    KAUST Repository

    Donaldson, Lara Elizabeth

    2016-05-11

    Background Cyclic nucleotides have been shown to play important signaling roles in many physiological processes in plants including photosynthesis and defence. Despite this, little is known about cyclic nucleotide-dependent signaling mechanisms in plants since the downstream target proteins remain unknown. This is largely due to the fact that bioinformatics searches fail to identify plant homologs of protein kinases and phosphodiesterases that are the main targets of cyclic nucleotides in animals. Methods An affinity purification technique was used to identify cyclic nucleotide binding proteins in Arabidopsis thaliana. The identified proteins were subjected to a computational analysis that included a sequence, transcriptional co-expression and functional annotation analysis in order to assess their potential role in plant cyclic nucleotide signaling. Results A total of twelve cyclic nucleotide binding proteins were identified experimentally including key enzymes in the Calvin cycle and photorespiration pathway. Importantly, eight of the twelve proteins were shown to contain putative cyclic nucleotide binding domains. Moreover, the identified proteins are post-translationally modified by nitric oxide, transcriptionally co-expressed and annotated to function in hydrogen peroxide signaling and the defence response. The activity of one of these proteins, GLYGOLATE OXIDASE 1, a photorespiratory enzyme that produces hydrogen peroxide in response to Pseudomonas, was shown to be repressed by a combination of cGMP and nitric oxide treatment. Conclusions We propose that the identified proteins function together as points of cross-talk between cyclic nucleotide, nitric oxide and reactive oxygen species signaling during the defence response.

  5. Measurement of purine derivatives and creatinine in urine by HPLC

    International Nuclear Information System (INIS)

    Piani, B.; Fabro, C.; Susmel, P.

    2004-01-01

    Two HPLC methods to measure the purine derivatives (PD, including allantoin, uric acid, hypoxanthine and xanthine) and creatinine content in urine are described. PD separation and quantification were achieved using two Spherisorb ODS 2 reversed phase columns connected in series (4.6 x 250 mm) and a Spherisorb ODS 2 Waters pre-column and a Perkin Elmer pump with an auto sampler. The mobile phase was NH 4 H 2 PO 4 :NH 4 H 2 PO 4 -acetonitrile (80:20), which was used at a flow rate of 0.8 ml/min and the detection wavelength was at 190 nm. The average recoveries of standard compounds added to urine samples were satisfactory (92-106%) and the low detection limits (0.7-3.4 μM) permitted the precise determination of these compounds in urine. Separation and quantification of creatinine was achieved using one Spherisorb ODS 2 reversed phase column (4.6 x 250 mm) and one Spherisorb ODS 2 Waters pre-column and a Perkin Elmer pump with an auto sampler. The mobile phase was NH 4 H 2 PO 4 :NH 4 H 2 PO 4 -acetonitrile (80:20), used at a flow rate of 1.00 ml/min and the detection was at 190 nm. The mean recovery (3 measurements) of standard solution added to urine samples was 101%; detection limit was 7.9 μM. (author)

  6. Synthesis of (purin-6-yl)acetates and 6-(2-hydroxyethyl)purines via cross-couplings of 6-chloropurines with the Reformatsky reagent

    Czech Academy of Sciences Publication Activity Database

    Hasník, Zbyněk; Šilhár, Peter; Hocek, Michal

    2007-01-01

    Roč. 48, č. 32 (2007), s. 5589-5592 ISSN 0040-4039 R&D Projects: GA MŠk 1M0508; GA AV ČR 1QS400550501 Institutional research plan: CEZ:AV0Z40550506 Keywords : purines * nucleosides * cross-coupling reactions Subject RIV: CC - Organic Chemistry Impact factor: 2.615, year: 2007

  7. Bacterial nucleotide-based second messengers.

    Science.gov (United States)

    Pesavento, Christina; Hengge, Regine

    2009-04-01

    In all domains of life nucleotide-based second messengers transduce signals originating from changes in the environment or in intracellular conditions into appropriate cellular responses. In prokaryotes cyclic di-GMP has emerged as an important and ubiquitous second messenger regulating bacterial life-style transitions relevant for biofilm formation, virulence, and many other bacterial functions. This review describes similarities and differences in the architecture of the cAMP, (p)ppGpp, and c-di-GMP signaling systems and their underlying signaling principles. Moreover, recent advances in c-di-GMP-mediated signaling will be presented and the integration of c-di-GMP signaling with other nucleotide-based signaling systems will be discussed.

  8. Nucleotides, Nucleosides, and Nucleobases

    DEFF Research Database (Denmark)

    Jensen, Kaj Frank; Dandanell, Gert; Hove-Jensen, Bjarne

    2008-01-01

    We review literature on the metabolism of ribo- and deoxyribonucleotides, nucleosides, and nucleobases in Escherichia coli and Salmonella,including biosynthesis, degradation, interconversion, and transport. Emphasis is placed on enzymology and regulation of the pathways, at both the level of gene...

  9. The Role of Cyclic Nucleotide Signaling Pathways in Cancer: Targets for Prevention and Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, Alexandra M.; Piazza, Gary A. [Drug Discovery Research Center, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Ave, Suite 3029, Mobile, AL 36604 (United States); Tinsley, Heather N., E-mail: htinsley@montevallo.edu [Department of Biology, Chemistry, and Mathematics, University of Montevallo, Station 6480, Montevallo, AL 35115 (United States)

    2014-02-26

    For more than four decades, the cyclic nucleotides cyclic AMP (cAMP) and cyclic GMP (cGMP) have been recognized as important signaling molecules within cells. Under normal physiological conditions, cyclic nucleotides regulate a myriad of biological processes such as cell growth and adhesion, energy homeostasis, neuronal signaling, and muscle relaxation. In addition, altered cyclic nucleotide signaling has been observed in a number of pathophysiological conditions, including cancer. While the distinct molecular alterations responsible for these effects vary depending on the specific cancer type, several studies have demonstrated that activation of cyclic nucleotide signaling through one of three mechanisms—induction of cyclic nucleotide synthesis, inhibition of cyclic nucleotide degradation, or activation of cyclic nucleotide receptors—is sufficient to inhibit proliferation and activate apoptosis in many types of cancer cells. These findings suggest that targeting cyclic nucleotide signaling can provide a strategy for the discovery of novel agents for the prevention and/or treatment of selected cancers.

  10. Association of poly-purine/poly-pyrimidine sequences with meiotic recombination hot spots

    Directory of Open Access Journals (Sweden)

    Pitt Joel PW

    2006-07-01

    Full Text Available Abstract Background Meiotic recombination events have been found to concentrate in 1–2.5 kilo base regions, but these recombination hot spots do not share a consensus sequence and why they occur at specific sites is not fully understood. Some previous evidence suggests that poly-purine/poly-pyrimidine (poly-pu/py tracts (PPTs, a class of sequence with distinctive biochemical properties, could be involved in recombination, but no general association of PPTs with meiotic recombination hot spots has previously been reported. Results We used computational methods to investigate in detail the relationship between PPTs and hot spots. We show statistical associations of PPT frequency with hot spots of meiotic recombination initiating lesions, double-strand breaks, in the genome of the yeast S. cerevisiae and with experimentally well characterized human meiotic recombination hot spots. Supporting a possible role of poly-pu/py-rich sequences in hot spot recombination, we also found that all three single nucleotide polymorphisms previously shown to be associated with human hot spot activity changes occur within sequence contexts of 14 bp or longer that are 85% or more poly-pu/py and at least 70% G/C. These polymorphisms are all close to the hot spot mid points. Comparing the sequences of experimentally characterized human hot spots with the orthologous regions of the chimpanzee genome previously shown not to contain hot spots, we found that in all five cases in which comparisons for the hot spot central regions are possible with publicly available sequence data, there are differences near the human hot spot mid points within sequences 14 bp or longer consisting of more than 80% poly-pu/py and at least 50% G/C. Conclusion Our results, along with previous evidence for the unique biochemical properties and recombination-stimulating potential of poly-pu/py-rich sequences, suggest that the possible functional involvement of this type of sequence in meiotic

  11. Photogeneration and reactivity of naphthoquinone methides as purine selective DNA alkylating agents.

    Science.gov (United States)

    Verga, Daniela; Nadai, Matteo; Doria, Filippo; Percivalle, Claudia; Di Antonio, Marco; Palumbo, Manlio; Richter, Sara N; Freccero, Mauro

    2010-10-20

    A one-step protecting-group-free synthesis of both 6-hydroxy-naphthalene-2-carbaldehyde and the bifunctional binaphthalenyl derivative afforded 6-hydroxymethylnaphthalen-2-ol, 6-methylaminomethyl-naphthalen-2-ol, [(2-hydroxy-3-naphthyl)methyl]trimethyl ammonium iodide, and a small library of bifunctional binol analogues in good yields. Irradiation of naphthol quaternary ammonium salt and binol-derivatives (X = OH, NHR, NMe(3)(+), OCOCH(3), and L-proline) at 310 and 360 nm resulted in the photogeneration of the 2,6-naphthoquinone-6-methide (NQM) and binol quinone methide analogues (BQMs) by a water-mediated excited-state proton transfer (ESPT). The hydration, the mono- and bis-alkylation reactions of morpholine and 2-ethanethiol, as N and S prototype nucleophiles, by the transient NQM (λ(max) 310, 330 nm) and BQMs (λ(max) 360 nm) were investigated in water by product distribution analysis and laser flash photolysis (LFP). Both the photogeneration and the reactivity of NQM and BQMs exhibited striking differences. BQMs were at least 2 orders of magnitude more reactive than NQM, and they were generated much more efficiently from a greater variety of photoprecursors including the hydroxymethyl, quaternary ammonium salt and several binol-amino acids. On the contrary, the only efficient precursor of NQM was the quaternary ammonium salt. All water-soluble BQM precursors were further investigated for their ability to alkylate and cross-link plasmid DNA and oligonucleotides by gel electrophoresis: the BQMs were more efficient than the isomeric o-BQM (binol quinone methide analogue of 2,3-naphthoquinone-3-methide). Sequence analysis by gel electrophoresis, HPLC, and MS showed that the alkylation occurred at purines, with a preference for guanine. In particular, a BQM was able to alkylate N7 of guanines resulting in depurination at the oligonucleotide level, and ribose loss at the nucleotide level. The photoreactivity of BQM precursors translated into photocytotoxic and

  12. Reduction of the degradation activity of umami-enhancing purinic ribonucleotide supplement in miso by the targeted suppression of acid phosphatases in the Aspergillus oryzae starter culture.

    Science.gov (United States)

    Marui, Junichiro; Tada, Sawaki; Fukuoka, Mari; Wagu, Yutaka; Shiraishi, Yohei; Kitamoto, Noriyuki; Sugimoto, Tatsuya; Hattori, Ryota; Suzuki, Satoshi; Kusumoto, Ken-Ichi

    2013-09-02

    Miso (fermented soybean paste) is a traditional Japanese fermented food, and is now used worldwide. The solid-state culture of filamentous fungus, Aspergillus oryzae, grown on rice is known as rice-koji, and is important as a starter for miso fermentation because of its prominent hydrolytic enzyme activities. Recently, commercial miso products have been supplemented with purinic ribonucleotides, such as inosine monophosphate (IMP) and guanine monophosphate, to enhance the characteristic umami taste of glutamate in miso. Because the purinic ribonucleotides are degraded by enzymes such as acid phosphatases in miso, heat inactivation is required prior to the addition of these flavorings. However, heat treatment is a costly process and reduces the quality of miso. Therefore, an approach to lower acid phosphatase activities in koji culture is necessary. Transcriptional analysis using an A. oryzae KBN8048 rice-koji culture showed that eight of the 13 acid phosphatase (aph) genes were significantly down-regulated by the addition of phosphoric acid in the preparation of the culture in a concentration-dependent manner, while aphC expression was markedly up-regulated under the same conditions. The eight down-regulated genes might be under the control of the functional counterpart of the Saccharomyces cerevisiae transcriptional activator Pho4, which specifically regulates phosphatase genes in response to the ambient phosphate availability. However, the regulatory mechanism of aphC was not clear. The IMP dephosphorylation activities in rice-koji cultures of KBN8048 and the aphC deletion mutant (ΔaphC) were reduced by up to 30% and 70%, respectively, in cultures with phosphoric acid, while protease and amylase activity, which is important for miso fermentation, was minimally affected. The miso products fermented using the rice-koji cultures of KBN8048 and ΔaphC prepared with phosphoric acid had reductions in IMP dephosphorylation activity of 80% and 90%, respectively, without

  13. Trichomonas vaginalis NTPDase and ecto-5'-nucleotidase hydrolyze guanine nucleotides and increase extracellular guanosine levels under serum restriction.

    Science.gov (United States)

    Menezes, Camila Braz; Durgante, Juliano; de Oliveira, Rafael Rodrigues; Dos Santos, Victor Hugo Jacks Mendes; Rodrigues, Luiz Frederico; Garcia, Solange Cristina; Dos Santos, Odelta; Tasca, Tiana

    2016-05-01

    Trichomonas vaginalis is the aethiologic agent of trichomoniasis, the most common non-viral sexually transmitted disease in the world. The purinergic signaling pathway is mediated by extracellular nucleotides and nucleosides that are involved in many biological effects as neurotransmission, immunomodulation and inflammation. Extracellular nucleotides can be hydrolyzed by a family of enzymes known as ectonucleotidases including the ecto-nucleoside triphosphate diphosphohydrolases (E-NTPDases) family which hydrolyses nucleosides triphosphate and diphosphate as preferential substrates and ecto-5'-nucleotidase which catalyzes the conversion of monophosphates into nucleosides. In T. vaginalis the E-NTPDase and ecto-5'-nucleotidase activities upon adenine nucleotides have already been characterized in intact trophozoites but little is known concerning guanine nucleotides and nucleoside. These enzymes may exert a crucial role on nucleoside generation, providing the purine sources for the synthesis de novo of these essential nutrients, sustaining parasite growth and survival. In this study, we investigated the hydrolysis profile of guanine-related nucleotides and nucleoside in intact trophozoites from long-term-grown and fresh clinical isolates of T. vaginalis. Knowing that guanine nucleotides are also substrates for T. vaginalis ectoenzymes, we evaluated the profile of nucleotides consumption and guanosine uptake in trophozoites submitted to a serum limitation condition. Results show that guanine nucleotides (GTP, GDP, GMP) were substrates for T. vaginalis ectonucleotidases, with expected kinetic parameters for this enzyme family. Different T. vaginalis isolates (two from the ATCC and nine fresh clinical isolates) presented a heterogeneous hydrolysis profile. The serum culture condition increased E-NTPDase and ecto-5'-nucleotidase activities with high consumption of extracellular GTP generating enhanced GDP, GMP and guanosine levels as demonstrated by HPLC, with final

  14. Research on urinary excretion of purine derivatives in ruminants: Past, present and future

    International Nuclear Information System (INIS)

    Chen, X.B.; Orskov, E.R.

    2004-01-01

    Research on urinary excretion of purine derivatives (PD), namely allantoin, uric acid, xanthine and hypoxanthine, in ruminants have been carried out with an objective to use the excretion of these purine metabolites as a parameter to estimate the intestinal flow of microbial protein. This paper reviews the published literature, from the first paper in 1931 to the current date. The current status of understanding in some key topics is discussed. The topics include: endogenous excretion, modelling the response of PD excretion to purine absorption, calculation of microbial N supply from PD excretion, use of spot urine measurement, possible use of plasma or milk PD as an alterative index, and applications in ruminant nutrition research. This review also covers the current understanding of PD excretion in different animal species, including sheep, cattle, goats, buffaloes, llamas, camels, yak and deer. Progress in analytical methods for the determination of purine derivatives is also discussed. Finally, areas of future research are highlighted. The paper stresses the need for more studies on metabolism of PD in the tissue, the kinetics of PD in the blood and physiological processes of renal excretion, so as to understand better the mechanism that accounts for the between-species and within species variation in PD excretion. Development of simpler and more rapid methods for defining the endogenous excretion and purine input-output relationship is also an area for future work. (author)

  15. Classification of pseudo pairs between nucleotide bases and amino acids by analysis of nucleotide–protein complexes

    Science.gov (United States)

    Kondo, Jiro; Westhof, Eric

    2011-01-01

    Nucleotide bases are recognized by amino acid residues in a variety of DNA/RNA binding and nucleotide binding proteins. In this study, a total of 446 crystal structures of nucleotide–protein complexes are analyzed manually and pseudo pairs together with single and bifurcated hydrogen bonds observed between bases and amino acids are classified and annotated. Only 5 of the 20 usual amino acid residues, Asn, Gln, Asp, Glu and Arg, are able to orient in a coplanar fashion in order to form pseudo pairs with nucleotide bases through two hydrogen bonds. The peptide backbone can also form pseudo pairs with nucleotide bases and presents a strong bias for binding to the adenine base. The Watson–Crick side of the nucleotide bases is the major interaction edge participating in such pseudo pairs. Pseudo pairs between the Watson–Crick edge of guanine and Asp are frequently observed. The Hoogsteen edge of the purine bases is a good discriminatory element in recognition of nucleotide bases by protein side chains through the pseudo pairing: the Hoogsteen edge of adenine is recognized by various amino acids while the Hoogsteen edge of guanine is only recognized by Arg. The sugar edge is rarely recognized by either the side-chain or peptide backbone of amino acid residues. PMID:21737431

  16. Effects of salicylic acid on post-ischaemic ventricular function and purine efflux in isolated mouse hearts.

    Science.gov (United States)

    Farthing, Don; Gehr, Lynne; Karnes, H Thomas; Sica, Domenic; Gehr, Todd; Larus, Terri; Farthing, Christine; Xi, Lei

    2007-01-01

    Acetyl salicylic acid (aspirin) is one of the most widely used drugs in the world. Various plasma concentrations of aspirin and its predominant metabolite, salicylic acid, are required for its antiarthritic (1.5-2.5 mM), anti-inflammatory (0.5-5.0 mM) or antiplatelet (0.18-0.36 mM) actions. A recent study demonstrated the inhibitory effects of both aspirin and salicylic acid on oxidative phosphorylation and ATP synthesis in isolated rat cardiac mitochondria in a dose-dependent manner (0-10 mM concentration range). In this context, the present study was conducted to determine the effects of salicylic acid on inosine efflux (a potential biomarker of acute cardiac ischaemia) as well as cardiac contractile function in the isolated mouse heart following 20 min of zero-flow global ischaemia. Inosine efflux was found at significantly higher concentrations in ischaemic hearts perfused with Krebs buffer fortified with 1.0 mM salicylic acid compared with those without salicylic acid (12575+/-3319 vs. 1437+/-348 ng ml(-1) min(-1), mean+/-SEM, n=6 per group, psalicylic acid potentiates 8.8-fold ATP nucleotide purine catabolism into its metabolites (e.g. inosine, hypoxanthine). Salicylic acid (0.1 or 1.0 mM) did not appreciably inhibit purine nucleoside phosphorylase (the enzyme converts inosine to hypoxanthine) suggesting the augmented inosine efflux was due to the salicylic acid effect on upstream elements of cellular respiration. Whereas post-ischaemic cardiac function was further depressed by 1.0 mM salicylic acid, perfusion with 0.1 mM salicylic acid led to a remarkable functional improvement despite moderately increased inosine efflux (2.7-fold). We conclude that inosine is a sensitive biomarker for detecting cardiac ischaemia and salicylic acid-induced effects on cellular respiration. However, the inosine efflux level appears to be a poor predictor of the individual post-ischaemic cardiac functional recovery in this ex vivo model.

  17. Enzymatic Regulation of Cytosolic Thymidine Kinase 1 and Mitochondrial Thymidine Kinase 2

    DEFF Research Database (Denmark)

    Munch-Petersen, Birgitte

    2010-01-01

    The central enzyme on the de novo pathway for synthesis of DNA precursors, the deoxyribonucleoside triphosphates, is ribonucleotide reductase (RNR). Deoxythymidine triphosphate (dTTP) has a key role in control of RNR activity shifting the specificity from pyrimidine to purine nucleotide reduction...

  18. Functionalized Solid Electrodes for Electrochemical Biosensing of Purine Nucleobases and Their Analogues: A Review

    Science.gov (United States)

    Sharma, Vimal Kumar; Jelen, Frantisek; Trnkova, Libuse

    2015-01-01

    Interest in electrochemical analysis of purine nucleobases and few other important purine derivatives has been growing rapidly. Over the period of the past decade, the design of electrochemical biosensors has been focused on achieving high sensitivity and efficiency. The range of existing electrochemical methods with carbon electrode displays the highest rate in the development of biosensors. Moreover, modification of electrode surfaces based on nanomaterials is frequently used due to their extraordinary conductivity and surface to volume ratio. Different strategies for modifying electrode surfaces facilitate electron transport between the electrode surface and biomolecules, including DNA, oligonucleotides and their components. This review aims to summarize recent developments in the electrochemical analysis of purine derivatives, as well as discuss different applications. PMID:25594595

  19. Measurement and application of purine derivatives: Creatinine ratio in spot urine samples of ruminants

    International Nuclear Information System (INIS)

    Chen, X.B.; Jayasuriya, M.C.N.; Makkar, H.P.S.

    2004-01-01

    The daily excretion of purine derivatives in urine has been used to estimate the supply of microbial protein to ruminant animals. The method provides a simple and non-invasive tool to indicate the nutritional status of farm animals. However due to the need for complete collection of urine the potential application at farm level is restricted. Research conducted under the FAO/IAEA Co-ordinated Research Project has indicated that it is possible to use the purine derivatives:creatinine ratio measured in several spot urine samples collected within a day, as an index of microbial protein supply in a banding system for farm application. Some theoretical and experimental aspects in the measurement of purine derivatives:creatinine ratio in spot urine samples and the possible application of the banding system at the farm level are discussed. (author)

  20. Growth in rice cells requires de novo purine biosynthesis by the blast fungus Magnaporthe oryzae

    Science.gov (United States)

    Fernandez, Jessie; Yang, Kuan Ting; Cornwell, Kathryn M.; Wright, Janet D.; Wilson, Richard A.

    2013-01-01

    Increasing incidences of human disease, crop destruction and ecosystem perturbations are attributable to fungi and threaten socioeconomic progress and food security on a global scale. The blast fungus Magnaporthe oryzae is the most devastating pathogen of cultivated rice, but its metabolic requirements in the host are unclear. Here we report that a purine-requiring mutant of M. oryzae could develop functional appressoria, penetrate host cells and undergo the morphogenetic transition to elaborate bulbous invasive hyphae from primary hyphae, but further in planta growth was aborted. Invasive hyphal growth following rice cell ingress is thus dependent on de novo purine biosynthesis by the pathogen and, moreover, plant sources of purines are neither available to the mutant nor required by the wild type during the early biotrophic phase of infection. This work provides new knowledge about the metabolic interface between fungus and host that might be applicable to other important intracellular fungal pathogens. PMID:23928947

  1. Functionalized Solid Electrodes for Electrochemical Biosensing of Purine Nucleobases and Their Analogues: A Review

    Directory of Open Access Journals (Sweden)

    Vimal Kumar Sharma

    2015-01-01

    Full Text Available Interest in electrochemical analysis of purine nucleobases and few other important purine derivatives has been growing rapidly. Over the period of the past decade, the design of electrochemical biosensors has been focused on achieving high sensitivity and efficiency. The range of existing electrochemical methods with carbon electrode displays the highest rate in the development of biosensors. Moreover, modification of electrode surfaces based on nanomaterials is frequently used due to their extraordinary conductivity and surface to volume ratio. Different strategies for modifying electrode surfaces facilitate electron transport between the electrode surface and biomolecules, including DNA, oligonucleotides and their components. This review aims to summarize recent developments in the electrochemical analysis of purine derivatives, as well as discuss different applications.

  2. Purine restriction induces pronounced translational upregulation of the NT1 adenosine/pyrimidine nucleoside transporter in Leishmania major.

    Science.gov (United States)

    Ortiz, Diana; Valdés, Raquel; Sanchez, Marco A; Hayenga, Johanna; Elya, Carolyn; Detke, Siegfried; Landfear, Scott M

    2010-10-01

    Leishmania and other parasitic protozoa are unable to synthesize purines de novo and are reliant upon purine nucleoside and nucleobase transporters to import preformed purines from their hosts. To study the roles of the four purine permeases NT1-NT4 in Leishmania major, null mutants in each transporter gene were prepared and the effect of each gene deletion on purine uptake was monitored. Deletion of the NT3 purine nucleobase transporter gene or both NT3 and the NT2 nucleoside transporter gene resulted in pronounced upregulation of adenosine and uridine uptake mediated by the NT1 permease and also induced up to a 200-fold enhancement in the level of the NT1 protein but not mRNA. A similar level of upregulation of NT1 was achieved in wild-type promastigotes that were transferred to medium deficient in purines. Pulse labelling and treatment of cells with the translation inhibitor cycloheximide revealed that control of NT1 expression occurs primarily at the level of translation and not protein turnover. These observations imply the existence of a translational control mechanism that enhances the ability of Leishmania parasites to import essential purines when they are present at limiting concentrations. © 2010 Blackwell Publishing Ltd.

  3. Excretion of purine base derivatives after intake of bacterial protein meal in pigs

    DEFF Research Database (Denmark)

    Hellwing, Anne Louise Frydendahl; Tauson, Anne-Helene; Skrede, A.

    2007-01-01

    Bacterial protein meal has a high content ofprotein but also of RNA and DNA. Sixteen barrows were allocated to four diets containing increasing levels of bacterial protein meal (BPM), from weaning to 80 kg live weight, to evaluate whether the RNA and DNA contents of BPM influenced the retention...... of nitrogen. It was hypothesised that an increased intake of RNA and DNA would lead to an increased urinary excretion of purine base derivatives and increased plasma concentrations. Retention of nitrogen was unaffected by dietary content of BPM (P=0.08) and the urinary excretion of purine base derivatives...

  4. Caracterización de la microbiota bacteriana presente en biorreactores de microalgas alimentados con purines

    OpenAIRE

    Prado Carrascal, Ana Isabel

    2016-01-01

    La producción intensiva ganadera, con una alta concentración de animales estabulados, conlleva la generación de grandes cantidades de residuos semilíquidos o purines, cuyo vertido no controlado puede generar contaminación tanto en los suelos como en las aguas superficiales y subterráneas, lo que provoca importantes problemas ambientales que han obligado a legislar su gestión. El tratamiento de los purines tiene por objetivo básico reducir la materia orgánica y el contenido de nutrientes, lo q...

  5. Partition coefficients of some purine derivatives and its application to pharmacokinetics.

    Science.gov (United States)

    Chrzanowska, M; Sobiak, J; Kuehn, M; Dorawa, E; Hermann, T

    2009-12-01

    Metazathioprine (MAZA), a methylated derivative of azathioprine (AZA), demonstrated the greatest values of apparent and specific partition coefficients in n-octanol/phosphate buffer at pH 5.7 and pH 7.4 among purine derivatives such as 6-mercaptopurine (6-MP), 6-thioguanine (6-TG) and AZA. Introduction of a methyl group into the imidazole ring of AZA increases lipophilic properties of MAZA compared to AZA. Mass balance of purine derivatives in n-octanol and in phosphate buffer indicated their chemical stability in those media.

  6. An unusual mode of DNA duplex association: Watson-Crick interaction of all-purine deoxyribonucleic acids.

    Science.gov (United States)

    Battersby, Thomas R; Albalos, Maria; Friesenhahn, Michel J

    2007-05-01

    Nucleic acid duplexes associating through purine-purine base pairing have been constructed and characterized in a remarkable demonstration of nucleic acids with mixed sequence and a natural backbone in an alternative duplex structure. The antiparallel deoxyribose all-purine duplexes associate specifically through Watson-Crick pairing, violating the nucleobase size-complementarity pairing convention found in Nature. Sequence-specific recognition displayed by these structures makes the duplexes suitable, in principle, for information storage and replication fundamental to molecular evolution in all living organisms. All-purine duplexes can be formed through association of purines found in natural ribonucleosides. Key to the formation of these duplexes is the N(3)-H tautomer of isoguanine, preferred in the duplex, but not in aqueous solution. The duplexes have relevance to evolution of the modern genetic code and can be used for molecular recognition of natural nucleic acids.

  7. Direct determination of tautomerism in purine derivatives by low-temperature NMR spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Sečkářová, P.; Marek, R.; Maliňáková, K.; Kolehmainen, E.; Hocková, Dana; Hocek, Michal; Sklenář, V.

    2004-01-01

    Roč. 45, č. 33 (2004), s. 6259-6263 ISSN 0040-4039 R&D Projects: GA MŠk LN00A016 Institutional research plan: CEZ:AV0Z4055905 Keywords : purine * NMR * tautomerism Subject RIV: CC - Organic Chemistry Impact factor: 2.484, year: 2004

  8. An Efficient and Facile Methodology for Bromination of Pyrimidine and Purine Nucleosides with Sodium Monobromoisocyanurate (SMBI

    Directory of Open Access Journals (Sweden)

    Roger Stromberg

    2013-10-01

    Full Text Available An efficient and facile strategy has been developed for bromination of nucleosides using sodium monobromoisocyanurate (SMBI. Our methodology demonstrates bromination at the C-5 position of pyrimidine nucleosides and the C-8 position of purine nucleosides. Unprotected and also several protected nucleosides were brominated in moderate to high yields following this procedure.

  9. 2,6,9-Trisubstituted purines as CRK3 kinase inhibitors with antileishmanial activity in vitro

    Czech Academy of Sciences Publication Activity Database

    Řezníčková, Eva; Popa, Alexandr; Gucký, Tomáš; Zatloukal, Marek; Havlíček, Libor; Bazgier, Václav; Berka, K.; Jorda, Radek; Popa, Igor; Nasereddin, A.; Jaffe, Ch. L.; Kryštof, Vladimír; Strnad, Miroslav

    2015-01-01

    Roč. 25, č. 11 (2015), s. 2298-2301 ISSN 0960-894X R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Purine * Cyclin-dependent kinase * Leishmania Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.486, year: 2015

  10. Catalytic carbene transfer allows the direct customization of cyclic purine dinucleotides.

    Science.gov (United States)

    Fei, Na; Häussinger, Daniel; Blümli, Seraina; Laventie, Benoît-Joseph; Bizzini, Lorenzo D; Zimmermann, Kaspar; Jenal, Urs; Gillingham, Dennis

    2014-08-11

    We describe a simple method for the direct modification of nucleobases in cyclic purine dinucleotides, important signalling molecules in both prokaryotes and eukaryotes. The method tolerates all members of the cyclic dinucleotide family and could be used to modulate their function or introduce useful side-chains such as fluorophores and photo-crosslinking groups.

  11. Absorption and Intermediary Metabolism of Purines and Pyrimidines in Lactating Dairy Cows

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Stentoft; Røjen, Betina Amdisen; Jensen, Søren Krogh

    2015-01-01

    About 20 % of ruminal microbial N in dairy cows derives from purines and pyrimidines; however, their intermediary metabolism and contribution to the overall N metabolism has sparsely been described. In the present study, the postprandial patterns of net portal-drained viscera (PDV) and hepatic...

  12. Aplicaci??n de humedales artificiales para la depuraci??n de purines de granjas porcinas

    OpenAIRE

    Blanco Rubio, Iv??n

    2014-01-01

    204 p. El principal objetivo de este trabajo de investigaci??n es proporcionar informaci??n relevante sobre el funcionamiento y dimensionado de los sistemas de humedales artificiales de tipo horizontal para el tratamiento de la fracci??n l??quida de purines de cerdo

  13. Interactions of trimeric purine nucleoside phosphorylases with ground state analogues - calorimetric and fluorimetric studies

    Czech Academy of Sciences Publication Activity Database

    Wielgus-Kutrowska, B.; Frank, J.; Holý, Antonín; Koellner, G.; Bzowska, A.

    2003-01-01

    Roč. 22, 5/8 (2003), s. 1695-1698 ISSN 1525-7770 Grant - others:PCSR(PL) 6 P04A04416; PCSR(PL) 3 P04A03524 Institutional research plan: CEZ:AV0Z4055905 Keywords : purine nucleoside phosphorylase * fluorescence Subject RIV: CC - Organic Chemistry Impact factor: 0.813, year: 2003

  14. Urinary excretion of purine derivatives in Yerli Kara cattle

    International Nuclear Information System (INIS)

    Cetinkaya, N.; Guecues, A. I.; Oezcan, H.; Ulutuerk, S.; Yaman, S.

    2000-01-01

    The urinary excretion of purine derivatives (PD) was measured in four Yerli Kara bulls in two experiments, a fasting experiment lasting for 7 days and the other , where animals were given a diet containing 30% wheat straw and 70% compounded feed at four levels of intake (40,60,80 and 95% of voluntary feed intake). In the second experiment, which was carried out according to a 4x4 Latin Square design, four animals receiving 60 and 95% levels of intake were also given a single injection of 8- ''1''4C - uric acid via a jugular catheter. In Addition to the above two experiments the activity of xanthine oxidase and uricase in plasma, liver and intestinal mucosa obtained from Yerli Kara cattle was also determined.In the first experiment,fasting PD excretion averaged 0.691 (±0.053) mmol/kgW''0''.''7''5/d. Glomerular filtration rate GFR), tubular load and net re-absorption of allantoin between pre fasting and fasting were statistically significant (P<0.05). In the second experiment the recovery of injected 8 - ''1''4C - uric acid as total PD was 72.5 and 89.9% for 60 and 95% feeding levels, respectively. The average recovery was 81%. Plasma kinetics measured by 8 - ''1''4C - uric acid indicated that the total compartment pool size was 214.0 (±43.8) and 250.3 L (±29.5) for 60 and 95% feeding levels, respectively. GFR, tubular load and net re-absorption of uric acid and allantoin were not affected by feed intake. The allantoin : PD molar ratios changed between 0.78 to 0.93 for the four levels feed intake. There were significant correlations between PD excretion (expressed as mmol/d and μmol/kg W''0''.''7''5/d) and DDMI (kg/d and kg/kg W''0''.''7''5/d) and DOMI (kg/d)(r=0.99, P<0.01). The rate of PD excretion as a linear function of feed intake was 16.4 mmol/kg W''0''.''7''5 DDMI, 19.8 mmol/kg DDMI and 22.7 mmol/kg DOMI. Xanthine oxidase and uricase activities were; 1.34 (±0.72) and .44 (±0.05) and 0.13 (±0.03) and 0.08 (±0.03) unit/g fresh tissue in liver and

  15. Evolutionary convergence in the biosyntheses of the imidazole moieties of histidine and purines.

    Directory of Open Access Journals (Sweden)

    Alberto Vázquez-Salazar

    Full Text Available The imidazole group is an ubiquitous chemical motif present in several key types of biomolecules. It is a structural moiety of purines, and plays a central role in biological catalysis as part of the side-chain of histidine, the amino acid most frequently found in the catalytic site of enzymes. Histidine biosynthesis starts with both ATP and the pentose phosphoribosyl pyrophosphate (PRPP, which is also the precursor for the de novo synthesis of purines. These two anabolic pathways are also connected by the imidazole intermediate 5-aminoimidazole-4-carboxamide ribotide (AICAR, which is synthesized in both routes but used only in purine biosynthesis. Rather surprisingly, the imidazole moieties of histidine and purines are synthesized by different, non-homologous enzymes. As discussed here, this phenomenon can be understood as a case of functional molecular convergence.In this work, we analyze these polyphyletic processes and argue that the independent origin of the corresponding enzymes is best explained by the differences in the function of each of the molecules to which the imidazole moiety is attached. Since the imidazole present in histidine is a catalytic moiety, its chemical arrangement allows it to act as an acid or a base. On the contrary, the de novo biosynthesis of purines starts with an activated ribose and all the successive intermediates are ribotides, with the key β-glycosidic bondage joining the ribose and the imidazole moiety. This prevents purine ribonucleotides to exhibit any imidazole-dependent catalytic activity, and may have been the critical trait for the evolution of two separate imidazole-synthesizing-enzymes. We also suggest that, in evolutionary terms, the biosynthesis of purines predated that of histidine.As reviewed here, other biosynthetic routes for imidazole molecules are also found in extant metabolism, including the autocatalytic cyclization that occurs during the formation of creatinine from creatine phosphate

  16. Influence of infection by Toxoplasma gondii on purine levels and E-ADA activity in the brain of mice experimentally infected mice.

    Science.gov (United States)

    Tonin, Alexandre A; Da Silva, Aleksandro S; Casali, Emerson A; Silveira, Stephanie S; Moritz, Cesar E J; Camillo, Giovana; Flores, Mariana M; Fighera, Rafael; Thomé, Gustavo R; Morsch, Vera M; Schetinger, Maria Rosa C; Rue, Mario De La; Vogel, Fernanda S F; Lopes, Sonia T A

    2014-07-01

    The aim of this study was to assess the purine levels and E-ADA activity in the brain of mice (BALB/c) experimentally infected with Toxoplasma gondii. In experiment I (n=24) the mice were infected with RH strain of T. gondii, while in experiment II (n=36) they were infected with strain ME-49 of T. gondii. Our results showed that, for RH strain (acute phase), an increase in both periods in the levels of ATP, ADP, AMP, adenosine, hypoxanthine, xanthine (only on day 6 PI) and uric acid (only on day 6 PI). By the other hand, the RH strain led, on days 4 and 6 PI, to a reduction in the concentration of inosine. ME-49, a cystogenic strain, showed some differences in acute and chronic phase, since on day 6 PI the levels of ATP and ADP were increased, while on day 30 these same nucleotides were reduced. On day 60 PI, ME-49 induced a reduction in the levels of ATP, ADP, AMP, adenosine, inosine and xanthine, while uric acid was increased. A decrease of E-ADA activity was observed in brain on days 4 and 6 PI (RH), and 30 PI (ME-49); however on day 60 PI E-ADA activity was increased for infection by ME-49 strain. Therefore, it was possible to conclude that infection with T. gondii changes the purine levels and the activity of E-ADA in brain, which may be associated with neurological signs commonly observed in this disease. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Nucleotide excision repair in yeast

    NARCIS (Netherlands)

    Eijk, Patrick van

    2012-01-01

    Nucleotide Excision Repair (NER) is a conserved DNA repair pathway capable of removing a broad spectrum of DNA damage. In human cells a defect in NER leads to the disorder Xeroderma pigmentosum (XP). The yeast Saccharomyces cerevisiae is an excellent model organism to study the mechanism of NER. The

  18. Single nucleotide polymorphisms in the 5'-flanking region of the ...

    African Journals Online (AJOL)

    Prolactin (PRL), a polypeptide hormone synthesized and secreted by the animal's anterior pituitary gland, plays an important role in the regulation of mammalian lactation and avian reproduction. Considering the significant association between single nucleotide polymorphisms (SNPs) in the 5'-flanking region of PRL and ...

  19. Ethanol-induced activation of adenine nucleotide turnover. Evidence for a role of acetate

    International Nuclear Information System (INIS)

    Puig, J.G.; Fox, I.H.

    1984-01-01

    Consumption of alcohol causes hyperuricemia by decreasing urate excretion and increasing its production. Our previous studies indicate that ethanol administration increases uric acid production by increasing ATP degradation to uric acid precursors. To test the hypothesis that ethanol-induced increased urate production results from acetate metabolism and enhanced adenosine triphosphate turnover, we gave intravenous sodium acetate, sodium chloride and ethanol (0.1 mmol/kg per min for 1 h) to five normal subjects. Acetate plasma levels increased from 0.04 +/- 0.01 mM (mean +/- SE) to peak values of 0.35 +/- 0.07 mM and to 0.08 +/- 0.01 mM during acetate and ethanol infusions, respectively. Urinary oxypurines increased to 223 +/- 13% and 316 +/- 44% of the base-line values during acetate and ethanol infusions, respectively. Urinary radioactivity from the adenine nucleotide pool labeled with [8-14C] adenine increased to 171 +/- 27% and to 128 +/- 8% of the base-line values after acetate and ethanol infusions. These data indicate that both ethanol and acetate increase purine nucleotide degradation by enhancing the turnover of the adenine nucleotide pool. They support the hypothesis that acetate metabolism contributes to the increased production of urate associated with ethanol intake

  20. A Cascade of Thermophilic Enzymes As an Approach to the Synthesis of Modified Nucleotides.

    Science.gov (United States)

    Esipov, R S; Abramchik, Yu A; Fateev, I V; Konstantinova, I D; Kostromina, M A; Muravyova, T I; Artemova, K G; Miroshnikov, A I

    2016-01-01

    We propose a new approach for the synthesis of biologically important nucleotides which includes a multi-enzymatic cascade conversion of D -pentoses into purine nucleotides. The approach exploits nucleic acid exchange enzymes from thermophilic microorganisms: ribokinase, phosphoribosylpyrophosphate synthetase, and adenine phosphoribosyltransferase. We cloned the ribokinase gene from Thermus sp . 2.9, as well as two different genes of phosphoribosylpyrophosphate synthetase (PRPP-synthetase) and the adenine phosphoribosyltransferase (APR-transferase) gene from Thermus thermophilus HB27 into the expression vectors, generated high-yield E. coli producer strains, developed methods for the purification of the enzymes, and investigated enzyme substrate specificity. The enzymes were used for the conversion of D -pentoses into 5-phosphates that were further converted into 5-phospho-α- D -pentofuranose 1-pyrophosphates by means of ribokinase and PRPP-synthetases. Target nucleotides were obtained through the condensation of the pyrophosphates with adenine and its derivatives in a reaction catalyzed by APR-transferase. 2-Chloro- and 2-fluoroadenosine monophosphates were synthesized from D -ribose and appropriate heterobases in one pot using a system of thermophilic enzymes in the presence of ATP, ribokinase, PRPP-synthetase, and APR-transferase.

  1. The first 3':5'-cyclic nucleotide-amino acid complex: L-His-cIMP.

    Science.gov (United States)

    Slepokura, Katarzyna

    2012-08-01

    In the crystal structure of the L-His-cIMP complex, i.e. L-histidinium inosine 3':5'-cyclic phosphate [systematic name: 5-(2-amino-2-carboxyethyl)-1H-imidazol-3-ium 7-hydroxy-2-oxo-6-(6-oxo-6,9-dihydro-1H-purin-9-yl)-4a,6,7,7a-tetrahydro-4H-1,3,5,2λ(5)-furo[3,2-d][1,3,2λ(5)]dioxaphosphinin-2-olate], C(6)H(10)N(3)O(2)(+)·C(10)H(10)N(4)O(7)P(-), the Hoogsteen edge of the hypoxanthine (Hyp) base of cIMP and the Hyp face are engaged in specific amino acid-nucleotide (His···cIMP) recognition, i.e. by abutting edge-to-edge and by π-π stacking, respectively. The Watson-Crick edge of Hyp and the cIMP phosphate group play a role in nonspecific His···cIMP contacts. The interactions between the cIMP anions (anti/C3'-endo/trans-gauche/chair conformers) are realized mainly between riboses and phosphate groups. The results for this L-His-cIMP complex, compared with those for the previously reported solvated L-His-IMP crystal structure, indicate a different nature of amino acid-nucleotide recognition and interactions upon the 3':5'-cyclization of the nucleotide phosphate group.

  2. Development of Equation Based on Urinary Purine Derivatives to Estimate Rumen Microbial Protein Production in Goats

    International Nuclear Information System (INIS)

    Jetana, Thongsuk; Abdullah, Norhani; Liang, Boo Juan; Syed Salim, Syed Jalaludin; Ho, Wan Yin

    2003-06-01

    Three experiments were conducted at the farm of the Universiti Putra Malaysia, Serdang, Selangor, Malaysia, to establish a model as an index for estimating rumen microbial protein production. In Experiment 1, six Ferral male goats (wt. 40.2±4.6 kg) were used to determine the endogenous purine derivatives (PD) excreted in the urine by fasting. In Experiment 2, four Ferral male goats (wt. 39.6±1.8 kg) were used to measure the proportion of plasma PD excreted in the urine by using [ 14 C]-uric acid as a marker at two levels of feed intake (40% and 80% voluntary intake), using an incomplete 2x4 Latin square experimental design. The feed consisted of 40% oil palm frond and 60% concentrate (OPFC). In Experiment 3, four Ferral male goats fed (OPFC)) were slaughtered and rumen contents were taken for measurements of purine and total nitrogen contents of mixed rumen microbes. The results showed that endogenous PD (allantoin, uric acid, xanthine and hypoxanthine) excreted in the urine obtained by the fasting trial was 202±17 μmol/kg BW 0 . 75 d - 1. The average percentage recovery of plasma PD excretion in the urine by using [ 14 C)-uric acid as a marker was 83±2.0% (cv=6.88, ranged 76.3-91.4%, n=8). Percentage recovery was not affected by levels of feed intake. The ratio of purine N: total N in the mixed rumen liquid associated bacteria (LAB) was 0.085. In this study, a preliminary model for goats was established by using the information from the recovery of labeled PD [ 14 C]-uric acid and the fasting PD excretion. The model obtained was Y 0.83X + 0.202 x BW 0 . 75 , where Y = PD excretion in the urine (mmol/d) X PD absorption at small intestine (mmol/d) BW 0 . 75 = Metabolic body weight (kg) Thus the microbial nitrogen based on total PD (MNpd) can be calculated as follows: MNpd = 70 x X = 0.992 x X (g/d) 0.085 x 0.83 x 1000 where 0.085 is the ratio of purine-N: total N in mixed rumen microbes, 0.83 is the average of digestibility of microbial purine from published

  3. Contents and retentions of free and total purine bases in lamb meat cooked by several household methods

    Directory of Open Access Journals (Sweden)

    P. Anfossi

    2011-03-01

    Full Text Available Concerns about the content of total and free purine bases in muscle foods and their retentions upon cooking have been since long established (Brulé et al., 1988. Recently, though, an important rôle has been acknowledged to dietary sources of preformed purines for the growth of tissues with a rapid turnover and for optimal function of the cellular immune response, up to the point that the positive features of these nutrients seem to outweigh by far the negative ones (ILSI, 1998. Scanty information exists about the total purine content of raw ovine meat, the only available sources of data being a survey by Herbel and Montag (1987 on purine and pyrimidine contents of protein-rich foods and the comprehensive collection of food composition tables compiled by Scherz and Senser (1994...

  4. Can Crystal Symmetry and Packing Influence the Active Site Conformation of Homohexameric Purine Nucleoside Phosphorylases?

    Directory of Open Access Journals (Sweden)

    Marija Luić

    2016-06-01

    Full Text Available It is generaly believed that enzymes retain most of their functionality in the crystal form due to the large solvent content of protein crystals. This is facilitated by the fact that their natural environment in solution is not too far from the one found in the crystal form. Nevertheless, if the nature of the enzyme is such to require conformational changes, overcoming of the crystal packing constraints may prove to be too difficult. Such conformational change is present in one class of enzymes (purine nucleoside phosphorylases, that is the subject of our scientific interest for many years. The influence of crystal symmetry and crystal packing on the conformation of the active sites in the case of homohexameric purine nucleoside phosphorylases is presented and analysed. This work is licensed under a Creative Commons Attribution 4.0 International License.

  5. Increase in urinary purines and pyrimidines in patients with methylmalonic aciduria combined with homocystinuria.

    Science.gov (United States)

    Porcu, Simona; Corda, Marcella; Lilliu, Franco; Contini, Liliana; Era, Benedetta; Traldi, Pietro; Fais, Antonella

    2010-06-03

    Methylmalonic aciduria combined with homocystinuria (MMA-HC) is the biochemical trait of a metabolic disorder resulting from impaired conversion of dietary cobalamin (cbl, or vitamin B12) to its two metabolically active forms. Effects on urinary purine and pyrimidine levels have not been described for this condition. Urine samples were collected from three patients with methylmalonic aciduria combined with homocystinuria and from 70 healthy subjects. Urinary purine and pyrimidine levels were quantitated by the use of LC/UV-Vis and LC/ESI/MS. Higher urine levels of pyrimidines were detected with both methods in patients compared to controls. Methylmalonic aciduria with homocystinuria is due to deficiency of the enzyme, cobalamin reductase. The enzyme defect leads to altered hepatic metabolism, which appears to modify circulating pyrimidine levels. Copyright 2010 Elsevier B.V. All rights reserved.

  6. Abiotic synthesis of purines and other heterocyclic compounds by the action of electrical discharges

    Science.gov (United States)

    Yuasa, S.; Flory, D.; Basile, B.; Oro, J.

    1984-01-01

    The synthesis of purines and pyrimidines using Oparin-Urey-type primitive earth atmospheres has been demonstrated by reacting methane, ethane, and ammonia in electrical discharges. Adenine, guaine, 4-aminoimidazole-5-carboxamide (AICA), and isocytosine have been identified by UV spectrometry and paper chromatography as the products of the reaction. The total yields of the identified heterocyclic compounds are 0.0023 percent. It is concluded that adenine synthesis occurs at a much lower concentration of hydrogen cyanide than has been shown by earlier studies. Pathways for the synthesis of purines from hydrogen cyanide are discussed, and a comparison of the heterocyclic compounds that have been identified in meteorites and in prebiotic reactions is presented.

  7. Estimation of microbial protein supply in ruminants using urinary purine derivatives

    International Nuclear Information System (INIS)

    Makkar, H.P.S.; Chen, X.B.

    2004-01-01

    This publication presents various models, describing the quantitative excretion of purine derivatives in urine, developed for various breeds of cattle and for sheep, goat, camel and buffalo and their use for estimation of microbial protein supply in ruminant livestock. It also describes progress made over the last decade in analytical methods for determining purine derivatives, and a unique approach for estimating microbial protein supply using spot urine samples developed under the FAO/IAEA CRP. This approach of using spot urine samples dispenses with quantitative recovery of urine, enabling its use by field and extension workers for evaluation of the nutritional status of farm animals. Future areas of research are also highlighted in the book. This book is a good source of reference for research workers, students and extension workers alike

  8. Synthesis and Cytotoxic Activity of Some New 2,6-Substituted Purines

    Directory of Open Access Journals (Sweden)

    Nageswara Rao Kode

    2011-07-01

    Full Text Available A seriesof twenty four acyclic unsaturated 2,6-substututed purines 5a-20b were synthesized. These compounds were evaluated for cytotoxic activity against NCI-60 DTP human tumor cell line screen at 10µMconcentration. N9-[(Z-4'-chloro-2'-butenyl-1'-yl]-2,6-dichloropurine(5a, N9-[4'-chloro-2'-butynyl-1'-yl]-2,6-dichloropurine(10a, N9-[(E-2',3'-dibromo-4'-chloro-2'-butenyl-1'-yl]-6-methoxypurine(14and N9-[4'-chloro-2'-butynyl-1'-yl]-6-(4-methoxyphenyl-purine(19exhibited highly potent cytotoxic activity with GI50 values in the 1–5 µM range for most human tumor cell lines. Other compounds exhibited moderate activity.

  9. Formate supplementation enhances folate-dependent nucleotide biosynthesis and prevents spina bifida in a mouse model of folic acid-resistant neural tube defects.

    Science.gov (United States)

    Sudiwala, Sonia; De Castro, Sandra C P; Leung, Kit-Yi; Brosnan, John T; Brosnan, Margaret E; Mills, Kevin; Copp, Andrew J; Greene, Nicholas D E

    2016-07-01

    The curly tail mouse provides a model for neural tube defects (spina bifida and exencephaly) that are resistant to prevention by folic acid. The major ct gene, responsible for spina bifida, corresponds to a hypomorphic allele of grainyhead-like 3 (Grhl3) but the frequency of NTDs is strongly influenced by modifiers in the genetic background. Moreover, exencephaly in the curly tail strain is not prevented by reinstatement of Grhl3 expression. In the current study we found that expression of Mthfd1L, encoding a key component of mitochondrial folate one-carbon metabolism (FOCM), is significantly reduced in ct/ct embryos compared to a partially congenic wild-type strain. This expression change is not attributable to regulation by Grhl3 or the genetic background at the Mthfd1L locus. Mitochondrial FOCM provides one-carbon units as formate for FOCM reactions in the cytosol. We found that maternal supplementation with formate prevented NTDs in curly tail embryos and also resulted in increased litter size. Analysis of the folate profile of neurulation-stage embryos showed that formate supplementation resulted in an increased proportion of formyl-THF and THF but a reduction in proportion of 5-methyl THF. In contrast, THF decreased and 5-methyl THF was relatively more abundant in the liver of supplemented dams than in controls. In embryos cultured through the period of spinal neurulation, incorporation of labelled thymidine and adenine into genomic DNA was suppressed by supplemental formate, suggesting that de novo folate-dependent biosynthesis of nucleotides (thymidylate and purines) was enhanced. We hypothesise that reduced Mthfd1L expression may contribute to susceptibility to NTDs in the curly tail strain and that formate acts as a one-carbon donor to prevent NTDs. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  10. The crystal structure of the hexameric purine nucleoside phosphorylase from Bacillus subtilis in complex with adenosine

    Energy Technology Data Exchange (ETDEWEB)

    Giuseppe, P.O.; Meza, A.N.; Martins, N.H.; Santos, C.R.; Murakami, M.T. [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil)

    2012-07-01

    Full text: Purine nucleoside phosphorylases (PNPs) play a key role in the purine-salvage pathway in both prokaryotes and eukaryotes. Its ribosyltransferase activity is of great biotechnological interest due to potential application in the synthesis of nucleoside analogues used in the treatment of antiviral infections and in anticancer chemotherapy. Trimeric PNPs are found mainly in vertebrates and are specific for 6-oxo-purines whereas hexameric PNPs are prevalent in prokaryotes and exhibit a broad range of substrates including 6-oxo and 6-amino purines. BsPNP233, the hexameric PNP from B. subtilis, is able to catalyze the bioconversion of ribavirin, an anti-viral drug, and is relatively thermostable, being a good target for industrial use. Here we report the crystal structures of BsPNP233 in the apo form and in complex with adenosine solved at 2.65 and 1.91 resolution, respectively. The apo and ligand-bound BsPNP233 subunits superposed with an overall r.m.s. deviation of 0.31 for all C{alpha} atoms, which suggests that no major conformational changes occur upon substrate binding. Based on the crystal structure of BsPNP233 in complex with adenosine we have defined the active site residues implicated in binding the ribose (H4{sup *}, R43{sup *}, M64, R87, E178, M179, E180) and the nitrogenous base (S90, C91, G92, S202, V177, F159). These residues are highly conserved among the bacterial hexameric PNPs, suggesting they share the same mode of interaction with the substrates. This work will probably contribute to a better understanding of the molecular basis for the broad substrate specificity of hexameric PNPs and to projects aiming the rational design of PNPs for industrial purposes. (author)

  11. Stacking of purines in water: the role of dipolar interactions in caffeine.

    Science.gov (United States)

    Tavagnacco, L; Di Fonzo, S; D'Amico, F; Masciovecchio, C; Brady, J W; Cesàro, A

    2016-05-11

    During the last few decades it has been ascertained that base stacking is one of the major contributions stabilizing nucleic acid conformations. However, the understanding of the nature of the interactions involved in the stacking process remains under debate and it is a subject of theoretical and experimental studies. Structural similarity between purine bases (guanine and adenine) in DNA and the caffeine molecule makes caffeine an excellent model for the purine bases. The present study clearly shows that dipolar interactions play a fundamental role in determining stacking of purine molecules in solution. In order to reach this achievement, polarized ultraviolet Raman resonant scattering experiments have been carried out on caffeine aqueous solutions as a function of concentration and temperature. The investigation pointed out at the aggregation and solvation properties, particularly at elevated temperatures. Kubo-Anderson theory was used as a framework to investigate the non-coincidence effect (NCE) occurring in the totally symmetric breathing modes of the purine rings, and in the bending modes of the methyl groups of caffeine. The NCE concentration dependence shows that caffeine aggregation at 80 °C occurs by planar stacking of the hydrophobic faces. The data clearly indicate that dipolar interactions determine the reorientational motion of the molecules in solution and are the driving force for the stacking of caffeine. In parallel, the observed dephasing times imply a change in caffeine interactions as a function of temperature and concentration. A decrease, at low water content, of the dephasing time for the ring breathing vibration mode indicates that self-association alters the solvation structure that is detectable at low concentration. These results are in agreement with simulation predictions and serve as an important validation of the models used in those calculations.

  12. Novel modified purine bases and nucleosides: new methodologies of synthesis and biological activity

    Czech Academy of Sciences Publication Activity Database

    Hocek, Michal

    -, č. 49 (2005), s. 29-30 ISSN 0261-3166. [International Symposium on Nucleic Acids Chemistry /4./. Fukuoka, 20.09.2005-22.09.2005] R&D Projects: GA ČR(CZ) GA203/03/0035; GA MŠk(CZ) 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : purines * nucleosides * synthesis Subject RIV: CC - Organic Chemistry

  13. Unraveling the cellular context of cyclic nucleotide signaling proteins by chemical proteomics

    NARCIS (Netherlands)

    Corradini, E.

    2015-01-01

    Understanding the molecular mechanisms which regulate signal transduction is fundamental to the development of therapeutic molecules for the treatment of several diseases. In particular, signaling proteins, such as cyclic nucleotide dependent enzymes are the orchestrators of many tissue functions.

  14. Effect of physiological status on endogenous excretion of purine derivatives in cattle

    International Nuclear Information System (INIS)

    Balcells, J.; Vicente, F.; Orellana-Boero, P.; Martin-Orue, S.; Gonzalez-Ronquillo, M.

    2004-01-01

    The present study examined the endogenous urinary excretion of purine derivatives (PD: allantoin and uric acid) in normally fed animals in different physiological states. Animals fitted with a simple rumen cannula and a T-shaped duodenal cannula were used in three separate experiments. In Experiment I, three heifers (about 8 months old; 225 ± 4.4 kg) fed a cereal based diet were used. In Experiment 11, two Friesian dry cows (about 24 months old; 696 ± 21 kg) fed at maintenance level on chopped barley straw and barley grain (50:50). In Experiment 3, three multiparous crossbreed Holstein-Friesian cows (560 ± 10 kg, average milk yield 25 ± 3.2 kg/d) in their third lactation were used. The cows were fed a mixed diet (48:52; roughage:concentrate). 15 N ammonium phosphate was infused continuously into the rumen to label microbial purine bases (PB). Duodenal flow of digesta and PB was determined using a dual marker system. After 72-80 h purine enrichment had reached plateau values in body pools and in urine. Daily endogenous PD excretion (μmol/W 0.75 ) obtained in dry cows (310 ± 31.0) were not significantly different from that obtained in growing steers (236 ± 6.0) but were consistently higher (512.4 ± 36.4) in lactating cows. (author)

  15. The Formation of Nucleobases from the Ultraviolet Photoirradiation of Purine in Simple Astrophysical Ice Analogues.

    Science.gov (United States)

    Materese, Christopher K; Nuevo, Michel; Sandford, Scott A

    2017-08-01

    Nucleobases are the informational subunits of RNA and DNA and are essential to all known forms of life. The nucleobases can be divided into two groups of molecules: the pyrimidine-based compounds that include uracil, cytosine, and thymine, and the purine-based compounds that include adenine and guanine. Previous work in our laboratory has demonstrated that uracil, cytosine, thymine, and other nonbiological, less common nucleobases can form abiotically from the UV photoirradiation of pyrimidine in simple astrophysical ice analogues containing combinations of H 2 O, NH 3 , and CH 4 . In this work, we focused on the UV photoirradiation of purine mixed with combinations of H 2 O and NH 3 ices to determine whether or not the full complement of biological nucleobases can be formed abiotically under astrophysical conditions. Room-temperature analyses of the resulting photoproducts resulted in the detection of adenine, guanine, and numerous other functionalized purine derivatives. Key Words: Pyrimidine-Nucleobases-Interstellar; Ices-Cometary; Ices-Molecular processes-Prebiotic chemistry. Astrobiology 17, 761-770.

  16. Substitution of Active Site Tyrosines with Tryptophan Alters the Free Energy for Nucleotide Flipping by Human Alkyladenine DNA Glycosylase†

    Science.gov (United States)

    Hendershot, Jenna M.; Wolfe, Abigail E.; O'Brien, Patrick J.

    2011-01-01

    Human alkyladenine DNA glycosylase (AAG) locates and excises a wide variety of structurally diverse alkylated and oxidized purine lesions from DNA to initiate the base excision repair pathway. Recognition of a base lesion requires flipping of the damaged nucleotide into a relatively open active site pocket between two conserved tyrosine residues, Y127 and Y159. We have mutated each of these amino acids to tryptophan and measured the kinetic effects on the nucleotide flipping and base excision steps. The Y127W and Y159W mutant proteins have robust glycosylase activity toward DNA containing 1,N6-ethenoadenine (εA), within 4-fold of that of the wildtype enzyme, raising the possibility that tryptophan fluorescence could be used to probe the DNA binding and nucleotide flipping steps. Stopped-flow fluorescence was used to compare the time-dependent changes in tryptophan fluorescence and εA fluorescence. For both mutants, the tryptophan fluorescence exhibited two-step binding with essentially identical rate constants as were observed for the εA fluorescence changes. These results provide evidence that AAG forms an initial recognition complex in which the active site pocket is perturbed and the stacking of the damaged base is disrupted. Upon complete nucleotide flipping, there is further quenching of the tryptophan fluorescence with coincident quenching of the εA fluorescence. Although these mutations do not have large effects on the rate constant for excision of εA, there are dramatic effects on the rate constants for nucleotide flipping that result in 40 to 100-fold decreases in the flipping equilibrium relative to wildtype. Most of this effect is due to an increased rate of unflipping, but surprisingly the Y159W mutation causes a 5-fold increase in the rate constant for flipping. The large effect on the equilibrium for nucleotide flipping explains the greater deleterious effects that these mutations have on the glycosylase activity toward base lesions that are in

  17. Regulation of adult neural progenitor cell functions by purinergic signaling.

    Science.gov (United States)

    Tang, Yong; Illes, Peter

    2017-02-01

    Extracellular purines are signaling molecules in the neurogenic niches of the brain and spinal cord, where they activate cell surface purinoceptors at embryonic neural stem cells (NSCs) and adult neural progenitor cells (NPCs). Although mRNA and protein are expressed at NSCs/NPCs for almost all subtypes of the nucleotide-sensitive P2X/P2Y, and the nucleoside-sensitive adenosine receptors, only a few of those have acquired functional significance. ATP is sequentially degraded by ecto-nucleotidases to ADP, AMP, and adenosine with agonistic properties for distinct receptor-classes. Nucleotides/nucleosides facilitate or inhibit NSC/NPC proliferation, migration and differentiation. The most ubiquitous effect of all agonists (especially of ATP and ADP) appears to be the facilitation of cell proliferation, usually through P2Y1Rs and sometimes through P2X7Rs. However, usually P2X7R activation causes necrosis/apoptosis of NPCs. Differentiation can be initiated by P2Y2R-activation or P2X7R-blockade. A key element in the transduction mechanism of either receptor is the increase of the intracellular free Ca 2+ concentration, which may arise due to its release from intracellular storage sites (G protein-coupling; P2Y) or due to its passage through the receptor-channel itself from the extracellular space (ATP-gated ion channel; P2X). Further research is needed to clarify how purinergic signaling controls NSC/NPC fate and how the balance between the quiescent and activated states is established with fine and dynamic regulation. GLIA 2017;65:213-230. © 2016 Wiley Periodicals, Inc.

  18. Nucleotide-binding oligomerization domain 1 regulates Porphyromonas gingivalis-induced vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 expression in endothelial cells through NF-κB pathway.

    Science.gov (United States)

    Wan, M; Liu, J; Ouyang, X

    2015-04-01

    Porphyromonas gingivalis has been shown to actively invade endothelial cells and induce vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) overexpression. Nucleotide-binding oligomerization domain 1 (NOD1) is an intracellular pattern recognition reporter, and its involvement in this process was unknown. This study focused on endothelial cells infected with P. gingivalis, the detection of NOD1 expression and the role that NOD1 plays in the upregulation of VCAM-1 and ICAM-1. The human umbilical vein endothelial cell line (ECV-304) was intruded by P. gingivalis W83, and cells without any treatment were the control group. Expression levels of NOD1, VCAM-1, ICAM-1, phosphorylated P65 between cells with and without treatment on both mRNA and protein levels were compared. Then we examined whether mesodiaminopimelic acid (NOD1 agonist) could increase VCAM-1 and ICAM-1 expression, meanwhile, NOD1 gene silence by RNA interference could reduce VCAM-1, ICAM-1 and phosphorylated P65 release. At last, we examined whether inhibition of NF-κB by Bay117082 could reduce VCAM-1 and ICAM- 1 expression. The mRNA levels were measured by real-time polymerase chain reaction, and protein levels by western blot or electrophoretic mobility shift assays (for phosphorylated P65). P. gingivalis invasion showed significant upregulation of NOD1, VCAM-1 and ICAM-1. NOD1 activation by meso-diaminopimelic acid increased VCAM-1 and ICAM-1 expression, and NOD1 gene silence reduced VCAM-1 and ICAM-1 release markedly. The NF-κB signaling pathway was activated by P. gingivalis, while NOD1 gene silence decreased the activation of NF-κB. Moreover, inhibition of NF-κB reduced VCAM-1 and ICAM-1 expression induced by P. gingivalis in endothelial cells. The results revealed that P. gingivalis induced NOD1 overexpression in endothelial cells and that NOD1 played an important role in the process of VCAM-1 and ICAM-1 expression in endothelial cells infected with P

  19. Heterogeneity and dynamics of the ligand recognition mode in purine-sensing riboswitches.

    Science.gov (United States)

    Jain, Niyati; Zhao, Liang; Liu, John D; Xia, Tianbing

    2010-05-04

    High-resolution crystal structures and biophysical analyses of purine-sensing riboswitches have revealed that a network of hydrogen bonding interactions appear to be largey responsible for discrimination of cognate ligands against structurally related compounds. Here we report that by using femtosecond time-resolved fluorescence spectroscopy to capture the ultrafast decay dynamics of the 2-aminopurine base as the ligand, we have detected the presence of multiple conformations of the ligand within the binding pockets of one guanine-sensing and two adenine-sensing riboswitches. All three riboswitches have similar conformational distributions of the ligand-bound state. The known crystal structures represent the global minimum that accounts for 50-60% of the population, where there is no significant stacking interaction between the ligand and bases of the binding pocket, but the hydrogen-bonding cage collectively provides an electronic environment that promotes an ultrafast ( approximately 1 ps) charge transfer pathway. The ligand also samples multiple conformations in which it significantly stacks with either the adenine or the uracil bases of the A21-U75 and A52-U22 base pairs that form the ceiling and floor of the binding pocket, respectively, but favors the larger adenine bases. These alternative conformations with well-defined base stacking interactions are approximately 1-1.5 kcal/mol higher in DeltaG degrees than the global minimum and have distinct charge transfer dynamics within the picosecond to nanosecond time regime. Inside the pocket, the purine ligand undergoes dynamic motion on the low nanosecond time scale, sampling the multiple conformations based on time-resolved anisotropy decay dynamics. These results allowed a description of the energy landscape of the bound ligand with intricate details and demonstrated the elastic nature of the ligand recognition mode by the purine-sensing riboswitches, where there is a dynamic balance between hydrogen bonding

  20. Astrocyte dysfunction following molybdenum-associated purine loading could initiate Parkinson's disease with dementia.

    Science.gov (United States)

    Bourke, Christopher A

    2018-01-01

    Sporadic or idiopathic Parkinson's disease is a movement disorder with a worldwide distribution, a long pre-clinical latent period and a frequent association with dementia. The combination of molybdenum deficiency and purine ingestion could explain the movement disorder, the distribution, the latent period and the dementia association. Recent studies in sheep have shown that molybdenum deficiency enables some dietary purines to accumulate in the central nervous system. This causes astrocyte dysfunction, altered neuromodulation and eventually irreversible central nervous system disease. Humans and sheep share the ability to salvage purines and this ability places humans at risk when they ingest xanthosine, inosine, adenosine and guanosine. Adenosine ingestion in molybdenum-deficient humans will lead to adenosine loading and potentially a disturbance to the A2a adenosine receptors in the nigro-striatum. This could result in Parkinson's disease. Guanosine ingestion in molybdenum-deficient humans will lead to guanosine loading and potentially a disturbance to the guanosine receptors in the hippocampus, amygdala and ventral striatum. This could result in dementia. The molybdenum content of the average daily diet in the United States is 0.07 ppm and in the United Kingdom 0.04 ppm. Central nervous system disease occurs in sheep at <0.04 ppm. Consistent with the role proposed for molybdenum deficiency in Parkinson's disease is the observation that affected individuals have elevated sulfur amino acid levels, depressed sulfate levels, and depressed uric acid levels. Likewise the geographical distribution of Parkinson's dementia complex on Guam corresponds with the distribution of molybdenum-deficient soils hence molybdenum-deficient food gardens on that island.

  1. The purine-utilizing bacterium Clostridium acidurici 9a: a genome-guided metabolic reconsideration.

    Directory of Open Access Journals (Sweden)

    Katrin Hartwich

    Full Text Available Clostridium acidurici is an anaerobic, homoacetogenic bacterium, which is able to use purines such as uric acid as sole carbon, nitrogen, and energy source. Together with the two other known purinolytic clostridia C. cylindrosporum and C. purinilyticum, C. acidurici serves as a model organism for investigation of purine fermentation. Here, we present the first complete sequence and analysis of a genome derived from a purinolytic Clostridium. The genome of C. acidurici 9a consists of one chromosome (3,105,335 bp and one small circular plasmid (2,913 bp. The lack of candidate genes encoding glycine reductase indicates that C. acidurici 9a uses the energetically less favorable glycine-serine-pyruvate pathway for glycine degradation. In accordance with the specialized lifestyle and the corresponding narrow substrate spectrum of C. acidurici 9a, the number of genes involved in carbohydrate transport and metabolism is significantly lower than in other clostridia such as C. acetobutylicum, C. saccharolyticum, and C. beijerinckii. The only amino acid that can be degraded by C. acidurici is glycine but growth on glycine only occurs in the presence of a fermentable purine. Nevertheless, the addition of glycine resulted in increased transcription levels of genes encoding enzymes involved in the glycine-serine-pyruvate pathway such as serine hydroxymethyltransferase and acetate kinase, whereas the transcription levels of formate dehydrogenase-encoding genes decreased. Sugars could not be utilized by C. acidurici but the full genetic repertoire for glycolysis was detected. In addition, genes encoding enzymes that mediate resistance against several antimicrobials and metals were identified. High resistance of C. acidurici towards bacitracin, acriflavine and azaleucine was experimentally confirmed.

  2. The purine-utilizing bacterium Clostridium acidurici 9a: a genome-guided metabolic reconsideration.

    Science.gov (United States)

    Hartwich, Katrin; Poehlein, Anja; Daniel, Rolf

    2012-01-01

    Clostridium acidurici is an anaerobic, homoacetogenic bacterium, which is able to use purines such as uric acid as sole carbon, nitrogen, and energy source. Together with the two other known purinolytic clostridia C. cylindrosporum and C. purinilyticum, C. acidurici serves as a model organism for investigation of purine fermentation. Here, we present the first complete sequence and analysis of a genome derived from a purinolytic Clostridium. The genome of C. acidurici 9a consists of one chromosome (3,105,335 bp) and one small circular plasmid (2,913 bp). The lack of candidate genes encoding glycine reductase indicates that C. acidurici 9a uses the energetically less favorable glycine-serine-pyruvate pathway for glycine degradation. In accordance with the specialized lifestyle and the corresponding narrow substrate spectrum of C. acidurici 9a, the number of genes involved in carbohydrate transport and metabolism is significantly lower than in other clostridia such as C. acetobutylicum, C. saccharolyticum, and C. beijerinckii. The only amino acid that can be degraded by C. acidurici is glycine but growth on glycine only occurs in the presence of a fermentable purine. Nevertheless, the addition of glycine resulted in increased transcription levels of genes encoding enzymes involved in the glycine-serine-pyruvate pathway such as serine hydroxymethyltransferase and acetate kinase, whereas the transcription levels of formate dehydrogenase-encoding genes decreased. Sugars could not be utilized by C. acidurici but the full genetic repertoire for glycolysis was detected. In addition, genes encoding enzymes that mediate resistance against several antimicrobials and metals were identified. High resistance of C. acidurici towards bacitracin, acriflavine and azaleucine was experimentally confirmed.

  3. Effect of training load structure on purine metabolism in middle-distance runners.

    Science.gov (United States)

    Zieliński, Jacek; Kusy, Krzysztof; Rychlewski, Tadeusz

    2011-09-01

    There are no studies analyzing the effect of training loads on purine metabolism during long training periods. The study's purpose was to evaluate the effect of training load changes and subsequent detraining on purine metabolism in middle-distance runners during a 1-yr cycle. In four characteristic points of the training cycle, loads assigned to five intensity zones, pre- and postexercise plasma hypoxanthine (Hx) and uric acid, and erythrocyte Hx-guanine phosphoribosyltransferase (HGPRT) activity were determined in 11 male middle-distance runners at the national level, practicing competitive sport for 8.1 ± 0.3 yr and with a mean age of 22.3 ± 0.7 yr, body mass of 73.0 ± 3.4 kg, and body height of 180 ± 2.2 cm. In the competition phase (CP), training loads in aerobic compensation and threshold zones decreased by 65.4% and by 20.5%, respectively. At the same time, anaerobic training loads increased by 132.5% in the VO(2max) zone and by 74.6% in the lactic acid tolerance zone. Postexercise Hx decreased significantly in CP by 6.2 μmol·L(-1). and increased in the transition phase (TP) by 17.4 μmol·L(-1). Both pre- and postexercise HGPRT activity increased significantly in CP by 9.3 nmol·mg(-1)·h(-1). and by 4.9 nmol·mg(-1)·h(-1). , respectively, and decreased significantly in TP by 10.6 nmol·mg(-1)·h(-1). and by 12.0 nmol·mg(-1)·h(-1). , respectively. A significant uric acid increase of 54 μmol·L(-1). was revealed merely in TP. The effect of anaerobic training on purine metabolism is significant despite of a very short total duration of anaerobic loads. Elevated preexercise HGPRT activity in CP suggests adaptation changes consisting in a "permanent readiness" for purine salvage. The detraining in TP leads to reverse adaptation changes. Probably, plasma Hx concentration and erythrocyte HGPRT activity may be considered as a useful measure of training status.

  4. Effect of purines on calcium-independent acetylcholine release at the mouse neuromuscular junction.

    Science.gov (United States)

    Veggetti, M; Muchnik, S; Losavio, A

    2008-07-17

    At the mouse neuromuscular junction, activation of adenosine A(1) and P2Y receptors inhibits acetylcholine release by an effect on voltage dependent calcium channels related to spontaneous and evoked secretion. However, an effect of purines upon the neurotransmitter-releasing machinery downstream of Ca(2+) influx cannot be ruled out. An excellent tool to study neurotransmitter exocytosis in a Ca(2+)-independent step is the hypertonic response. Intracellular recordings were performed on diaphragm fibers of CF1 mice to determine the action of the specific adenosine A(1) receptor agonist 2-chloro-N(6)-cyclopentyl-adenosine (CCPA) and the P2Y(12-13) agonist 2-methylthio-adenosine 5'-diphosphate (2-MeSADP) on the hypertonic response. Both purines significantly decreased such response (peak and area under the curve), and their effect was prevented by specific antagonists of A(1) and P2Y(12-13) receptors, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and N-[2-(methylthioethyl)]-2-[3,3,3-trifluoropropyl]thio-5'-adenylic acid, monoanhydride with dichloromethylenebiphosphonic acid, tetrasodium salt (AR-C69931MX), respectively. Moreover, incubation of preparations only with the antagonists induced a higher response compared with controls, suggesting that endogenous ATP/ADP and adenosine are able to modulate the hypertonic response by activating their specific receptors. To search for the intracellular pathways involved in this effect, we studied the action of CCPA and 2-MeSADP in hypertonicity in the presence of inhibitors of several pathways. We found that the effect of CPPA was prevented by the calmodulin antagonist N-(6-aminohexil)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) while that of 2-MeSADP was occluded by the protein kinase C antagonist chelerythrine and W-7. On the other hand, the inhibitors of protein kinase A (N-(2[pbromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide, H-89) and phosphoinositide-3 kinase (PI3K) (2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran

  5. Estimating rumen microbial protein supply for indigenous ruminants using nuclear and purine excretion techniques in Indonesia

    International Nuclear Information System (INIS)

    Soejono, M.; Yusiati, L.M.; Budhi, S.P.S.; Widyobroto, B.P.; Bachrudin, Z.

    1999-01-01

    The microbial protein supply to ruminants can be estimated based on the amount of purine derivatives (PD) excreted in the urine. Four experiments were conducted to evaluate the PD excretion method for Bali and Ongole cattle. In the first experiment, six male, two year old Bali cattle (Bos sondaicus) and six Ongole cattle (Bos indicus) of similar sex and age, were used to quantify the endogenous contribution to total PD excretion in the urine. In the second experiment, four cattle from each breed were used to examine the response of PD excretion to feed intake. 14 C-uric acid was injected in one single dose to define the partitioning ratio of renal:non-renal losses of plasma PD. The third experiment was conducted to examine the ratio of purine N:total N in mixed rumen microbial population. The fourth experiment measured the enzyme activities of blood, liver and intestinal tissues concerned with PD metabolism. The results of the first experiment showed that endogenous PD excretion was 145 ± 42.0 and 132 ± 20.0 μmol/kg W 0.75 /d, for Bali and Ongole cattle, respectively. The second experiment indicated that the proportion of plasma PD excreted in the urine of Bali and Ongole cattle was 0.78 and 0.77 respectively. Hence, the prediction of purine absorbed based on PD excretion can be stated as Y = 0.78 X + 0.145 W 0.75 and Y = 0.77 X + 0.132 W 0.75 for Bali and Ongole cattle, respectively. The third experiment showed that there were no differences in the ratio of purine N:total N in mixed rumen microbes of Bali and Ongole cattle (17% vs 18%). The last experiment, showed that intestinal xanthine oxidase activity of Bali cattle was lower than that of Ongole cattle (0.001 vs 0.015 μmol uric acid produced/min/g tissue) but xanthine oxidase activity in the blood and liver of Bali cattle was higher than that of Ongole cattle (3.48 vs 1.34 μmol/min/L plasma and 0.191 vs 0.131 μmol/min/g liver tissue). Thus, there was no difference in PD excretion between these two breeds

  6. Purine and its analogues and radiation damage in Bacillus megaterium spores

    International Nuclear Information System (INIS)

    Powers, E.L.

    1986-01-01

    As an extension of results obtained from radiation studies on caffeine both in other laboratories and more recently in this laboratory using the bacterial spore as the test system, six compounds with chemical structures closely resembling that of caffeine were tested as radiation modifiers. Of these compounds, purine, adenine and hypoxanthine resembled caffeine in sensitizing spores to radiation, while theobromine, xanthine and theophylline did not. These responses are discussed in relation to the electron sequestration hypothesis of cellular sensitization to high-energy radiation. (author)

  7. Purine and its analogues and radiation damage in Bacillus megaterium spores

    Energy Technology Data Exchange (ETDEWEB)

    Powers, E.L.

    1986-12-01

    As an extension of results obtained from radiation studies on caffeine both in other laboratories and more recently in this laboratory using the bacterial spore as the test system, six compounds with chemical structures closely resembling that of caffeine were tested as radiation modifiers. Of these compounds, purine, adenine and hypoxanthine resembled caffeine in sensitizing spores to radiation, while theobromine, xanthine and theophylline did not. These responses are discussed in relation to the electron sequestration hypothesis of cellular sensitization to high-energy radiation.

  8. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

    Science.gov (United States)

    Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  9. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions.

    Science.gov (United States)

    Coari, Kristin M; Martin, Rebecca C; Jain, Kopal; McGown, Linda B

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  10. pH dependent interaction of biofunctionalized CdS nanoparticles with nucleobases and nucleotides: A fluorimetric study

    International Nuclear Information System (INIS)

    Chatterjee, Anindita; Priyam, Amiya; Bhattacharya, Subhash C.; Saha, Abhijit

    2007-01-01

    The interaction of DNA bases and corresponding nucleotides with CdS nanoparticles (NPs), biofunctionalized by cysteine, has been investigated by absorption and fluorescence spectroscopy. Unique enhancement effect of adenine, in contrast to other nucleobases, on the luminescence of cysteine capped CdS (cys-CdS) NPs at both pH 7.5 and 10.5 was found, the extent of enhancement being much higher at pH 10.5. At the latter pH, the difference optical absorption spectra show development of new peak at 278 nm with corresponding decrease in the absorption of adenine at 260 nm, which is attributed to binding of adenine anion to the CdS surface through N7 of the purine ring. Appearance of a new band at 478 cm -1 and concomitant shift in the C 8 -N 7 vibrations to 1610 cm -1 in the FTIR spectra of cys-CdS NPs with adenine also suggest Cd-N7 binding on the particle surface. Amongst various nucleotides, ATP exhibited maximum luminescence enhancement on CdS NPs for a given change in concentration in the micro-molar range at physiological pH. A quantitative correlation between ATP concentration and PL enhancement of CdS NPs has been established, a step which in future might assist in developing new protocols for fluorescence sensing of adenine nucleotides under certain pathological conditions

  11. Nucleotide compositional asymmetry between the leading and lagging strands of eubacterial genomes

    KAUST Repository

    Qu, Hongzhu; Wu, Hao; Zhang, Tongwu; Zhang, Zhang; Hu, Songnian; Yu, Jun

    2010-01-01

    Nucleotide compositional asymmetry (NCA) between leading and lagging strands (LeS and LaS) is dynamic and diverse among eubacterial genomes due to different mutation and selection forces. A thorough investigation is needed in order to study the relationship between nucleotide composition dynamics and gene distribution biases. Based on a collection of 364 eubacterial genomes that were grouped according to a DnaE-based scheme (DnaE1-DnaE1, DnaE2-DnaE1, and DnaE3-PolC), we investigated NCA and nucleotide composition gradients at three codon positions and found that there was universal G-enrichment on LeS among all groups. This was due to a strong selection for G-heading (codon position1 or cp1) codons and mutation pressure that led to more G-ending (cp3) codons. Moreover, a slight T-enrichment of LeS due to the mutation of cytosine deamination at cp3 was universal among DnaE1-DnaE1 and DnaE2-DnaE1 genomes, but was not clearly seen among DnaE3-PolC genomes, in which A-enrichment of LeS was proposed to be the effect of selections unique to polC and a mutation bias toward A-richness at cp1 that may be a result of transcription-coupled DNA repair mechanisms. Furthermore, strand-biased gene distribution enhances the purine-richness of LeS for DnaE3-PolC genomes and T-richness of LeS for DnaE1-DnaE1 and DnaE2-dnaE1 genomes. © 2010 Institut Pasteur.

  12. Nucleotide compositional asymmetry between the leading and lagging strands of eubacterial genomes

    KAUST Repository

    Qu, Hongzhu

    2010-12-01

    Nucleotide compositional asymmetry (NCA) between leading and lagging strands (LeS and LaS) is dynamic and diverse among eubacterial genomes due to different mutation and selection forces. A thorough investigation is needed in order to study the relationship between nucleotide composition dynamics and gene distribution biases. Based on a collection of 364 eubacterial genomes that were grouped according to a DnaE-based scheme (DnaE1-DnaE1, DnaE2-DnaE1, and DnaE3-PolC), we investigated NCA and nucleotide composition gradients at three codon positions and found that there was universal G-enrichment on LeS among all groups. This was due to a strong selection for G-heading (codon position1 or cp1) codons and mutation pressure that led to more G-ending (cp3) codons. Moreover, a slight T-enrichment of LeS due to the mutation of cytosine deamination at cp3 was universal among DnaE1-DnaE1 and DnaE2-DnaE1 genomes, but was not clearly seen among DnaE3-PolC genomes, in which A-enrichment of LeS was proposed to be the effect of selections unique to polC and a mutation bias toward A-richness at cp1 that may be a result of transcription-coupled DNA repair mechanisms. Furthermore, strand-biased gene distribution enhances the purine-richness of LeS for DnaE3-PolC genomes and T-richness of LeS for DnaE1-DnaE1 and DnaE2-dnaE1 genomes. © 2010 Institut Pasteur.

  13. Different effects of guanine nucleotides (GDP and GTP) on protein-mediated mitochondrial proton leak.

    Science.gov (United States)

    Woyda-Ploszczyca, Andrzej M; Jarmuszkiewicz, Wieslawa

    2014-01-01

    In this study, we compared the influence of GDP and GTP on isolated mitochondria respiring under conditions favoring oxidative phosphorylation (OXPHOS) and under conditions excluding this process, i.e., in the presence of carboxyatractyloside, an adenine nucleotide translocase inhibitor, and/or oligomycin, an FOF1-ATP synthase inhibitor. Using mitochondria isolated from rat kidney and human endothelial cells, we found that the action of GDP and GTP can differ diametrically depending on the conditions. Namely, under conditions favoring OXPHOS, both in the absence and presence of linoleic acid, an activator of uncoupling proteins (UCPs), the addition of 1 mM GDP resulted in the state 4 (non-phosphorylating respiration)-state 3 (phosphorylating respiration) transition, which is characteristic of ADP oxidative phosphorylation. In contrast, the addition of 1 mM GTP resulted in a decrease in the respiratory rate and an increase in the membrane potential, which is characteristic of UCP inhibition. The stimulatory effect of GDP, but not GTP, was also observed in inside-out submitochondrial particles prepared from rat kidney mitochondria. However, the effects of GDP and GTP were more similar in the presence of OXPHOS inhibitors. The importance of these observations in connection with the action of UCPs, adenine nucleotide translocase (or other carboxyatractyloside-sensitive carriers), carboxyatractyloside- and purine nucleotide-insensitive carriers, as well as nucleoside-diphosphate kinase (NDPK) are considered. Because the measurements favoring oxidative phosphorylation better reflect in vivo conditions, our study strongly supports the idea that GDP cannot be considered a significant physiological inhibitor of UCP. Moreover, it appears that, under native conditions, GTP functions as a more efficient UCP inhibitor than GDP and ATP.

  14. Effect of tempe waste on excreation of purine derivatives and microbial–N supply in lactating Etawah crossbred goats

    Directory of Open Access Journals (Sweden)

    D.A Astuti

    2002-10-01

    Full Text Available The aim of this study was to evaluate excretion of purine derivatives and microbial–N supply in lactating Etawah crossbred goats fed with fermented soybean waste. Sixteen first lactating goats were randomly allotted into four dietary treatment groups that received 50% king grass plus R1: 50% concentrate, R2: 25% concentrate and 25% fresh tempe waste, R3: 25% concentrate and 25% fermented tempe waste, and R4: 25% concentrate and 25% gelatinizing of liquid tempe waste. Fermented tempe waste was made by fermentation of tempe waste (seed content of soybean using Aspergillus niger, while for the gellatinizing of liquid tempe waste was made by gelatinized with maize flour. Protein balance studies were conducted during two week trial and at the end of the research. Urinary protein and purine derivatives were collected for analysis. Microbial–N supply was calculated from purine derivatives excretion. Results showed that nitrogen consumptions were significantly different between R4 and three other treatments and apparent digestible nitrogen in R3 were higher than that of R4 (P<0.05. The nitrogen retention in R1 and R3 were higher than that of R2 and R4. Urinary purine derivatives in this study showed that allantoin, xanthine and hypoxanthine in R3 were higher than that of R4, while R1 and R2 were the same and the highest uric acid excretion and total purine derivatives were observed in R3. Microbial–N supply were significantly different between all treatments where R3 was the highest. This research concluded that fermented soybean waste had the highest total purine derivatives excretion and microbial–N supply to the lactating Etawah crossbred goats.

  15. Exploiting nucleotide composition to engineer promoters.

    Directory of Open Access Journals (Sweden)

    Manfred G Grabherr

    Full Text Available The choice of promoter is a critical step in optimizing the efficiency and stability of recombinant protein production in mammalian cell lines. Artificial promoters that provide stable expression across cell lines and can be designed to the desired strength constitute an alternative to the use of viral promoters. Here, we show how the nucleotide characteristics of highly active human promoters can be modelled via the genome-wide frequency distribution of short motifs: by overlapping motifs that occur infrequently in the genome, we constructed contiguous sequence that is rich in GC and CpGs, both features of known promoters, but lacking homology to real promoters. We show that snippets from this sequence, at 100 base pairs or longer, drive gene expression in vitro in a number of mammalian cells, and are thus candidates for use in protein production. We further show that expression is driven by the general transcription factors TFIIB and TFIID, both being ubiquitously present across cell types, which results in less tissue- and species-specific regulation compared to the viral promoter SV40. We lastly found that the strength of a promoter can be tuned up and down by modulating the counts of GC and CpGs in localized regions. These results constitute a "proof-of-concept" for custom-designing promoters that are suitable for biotechnological and medical applications.

  16. Bacillus subtilis guanine deaminase is encoded by the yknA gene and is induced during growth with purines as the nitrogen source

    DEFF Research Database (Denmark)

    Nygaard, P.; Bested, S. M.; Andersen, K. A. K.

    2000-01-01

    amino acid polypeptide and was preceded by a promoter sequence that is recognized by the A form of RNA polymerase. High levels of GDEase were found in cells grown with purines and intermediary compounds of the purine catabolic pathway as nitrogen sources. Allantoic acid, most likely, is a low molecular...

  17. Nucleotide sequence preservation of human mitochondrial DNA

    International Nuclear Information System (INIS)

    Monnat, R.J. Jr.; Loeb, L.A.

    1985-01-01

    Recombinant DNA techniques have been used to quantitate the amount of nucleotide sequence divergence in the mitochondrial DNA population of individual normal humans. Mitochondrial DNA was isolated from the peripheral blood lymphocytes of five normal humans and cloned in M13 mp11; 49 kilobases of nucleotide sequence information was obtained from 248 independently isolated clones from the five normal donors. Both between- and within-individual differences were identified. Between-individual differences were identified in approximately = to 1/200 nucleotides. In contrast, only one within-individual difference was identified in 49 kilobases of nucleotide sequence information. This high degree of mitochondrial nucleotide sequence homogeneity in human somatic cells is in marked contrast to the rapid evolutionary divergence of human mitochondrial DNA and suggests the existence of mechanisms for the concerted preservation of mammalian mitochondrial DNA sequences in single organisms

  18. Scambio, a novel guanine nucleotide exchange factor for Rho

    Directory of Open Access Journals (Sweden)

    Groffen John

    2004-04-01

    Full Text Available Abstract Background Small GTPases of the Rho family are critical regulators of various cellular functions including actin cytoskeleton organization, activation of kinase cascades and mitogenesis. For this reason, a major objective has been to understand the mechanisms of Rho GTPase regulation. Here, we examine the function of a novel protein, Scambio, which shares homology with the DH-PH domains of several known guanine nucleotide exchange factors for Rho family members. Results Scambio is located on human chromosome 14q11.1, encodes a protein of around 181 kDa, and is highly expressed in both heart and skeletal muscle. In contrast to most DH-PH-domain containing proteins, it binds the activated, GTP-bound forms of Rac and Cdc42. However, it fails to associate with V14RhoA. Immunofluorescence studies indicate that Scambio and activated Rac3 colocalize in membrane ruffles at the cell periphery. In accordance with these findings, Scambio does not activate either Rac or Cdc42 but rather, stimulates guanine nucleotide exchange on RhoA and its close relative, RhoC. Conclusion Scambio associates with Rac in its activated conformation and functions as a guanine nucleotide exchange factor for Rho.

  19. Alterations in tryptophan and purine metabolism in cocaine addiction: a metabolomic study.

    Science.gov (United States)

    Patkar, Ashwin A; Rozen, Steve; Mannelli, Paolo; Matson, Wayne; Pae, Chi-Un; Krishnan, K Ranga; Kaddurah-Daouk, Rima

    2009-10-01

    Mapping metabolic "signatures" can provide new insights into addictive mechanisms and potentially identify biomarkers and therapeutic targets. We examined the differences in metabolites related to the tyrosine, tryptophan, purine, and oxidative stress pathways between cocaine-dependent subjects and healthy controls. Several of these metabolites serve as biological indices underlying the mechanisms of reinforcement, toxicity, and oxidative stress. Metabolomic analysis was performed in 18 DSM-IV-diagnosed cocaine-dependent individuals with at least 2 weeks of abstinence and ten drug-free controls. Plasma concentrations of 37 known metabolites were analyzed and compared using a liquid chromatography electrochemical array platform. Multivariate analyses were used to study the relationship between severity of drug use [Addiction Severity Index (ASI) scores] and biological measures. Cocaine subjects showed significantly higher levels of n-methylserotonin (p cocaine and control groups with no overlap. Alterations in the methylation processes in the serotonin pathways and purine metabolism seem to be associated with chronic exposure to cocaine. Given the preliminary nature and cross-sectional design of the study, the findings need to be confirmed in larger samples of cocaine-dependent subjects, preferably in a longitudinal design.

  20. Genetic Screen Reveals the Role of Purine Metabolism in Staphylococcus aureus Persistence to Rifampicin

    Directory of Open Access Journals (Sweden)

    Rebecca Yee

    2015-12-01

    Full Text Available Chronic infections with Staphylococcus aureus such as septicemia, osteomyelitis, endocarditis, and biofilm infections are difficult to treat because of persisters. Despite many efforts in understanding bacterial persistence, the mechanisms of persister formation in S. aureus remain elusive. Here, we performed a genome-wide screen of a transposon mutant library to study the molecular mechanisms involved in persistence of community-acquired S. aureus. Screening of the library for mutants defective in persistence or tolerance to rifampicin revealed many genes involved in metabolic pathways that are important for antibiotic persistence. In particular, the identified mutants belonged to metabolic pathways involved in carbohydrate, amino acid, lipid, vitamin and purine biosynthesis. Five mutants played a role in purine biosynthesis and two mutants, purB, an adenylosuccinate lyase, and purM, a phosphoribosylaminoimidazole synthetase, were selected for further confirmation. Mutants purB and purM showed defective persistence compared to the parental strain USA300 in multiple stress conditions including various antibiotics, low pH, and heat stress. The defect in persistence was restored by complementation with the wildtype purB and purM gene in the respective mutants. These findings provide new insights into the mechanisms of persistence in S. aureus and provide novel therapeutic targets for developing more effective treatment for persistent infections due to S. aureus.

  1. The effect of plane of nutrition on the urinary purine derivative excretion in sheep and goats

    International Nuclear Information System (INIS)

    Poshiwa, X.; Tigere, A.; Ngongoni, N.T.; Manyuchi, B.; Chakoma, C.

    2004-01-01

    An experiment was conducted to determine the effect of plane of nutrition on purine derivative excretion and to develop a set of model equations that relate intake to the purine derivative (PD) excretion in sheep and goats. Four male Sabi sheep and four male Small-East African goats (four months old) were used. The trial was a 4 x 4 Latin square cross-over design to examine the response of PD excretion to feed intake. The four diets consisted of star grass (Cynodon nlemfuensis) hay fed ad libitum, and at 85, 70 or 55% of ad libitum. Total PD excretion increased with the increase in feed intake for both sheep and goats. However, the increase did not reach statistical significance (P > 0.05). The model equations relating digestible organic matter intake (X) to PD excretion (Y) were Y = 2.97 X + 0.15 (R 2 =0.72) and Y = 5.86 X - 0.33 (R 2 =0.99) for sheep and goats respectively. (author)

  2. A novel family of katanin-like 2 protein isoforms (KATNAL2), interacting with nucleotide-binding proteins Nubp1 and Nubp2, are key regulators of different MT-based processes in mammalian cells.

    Science.gov (United States)

    Ververis, Antonis; Christodoulou, Andri; Christoforou, Maria; Kamilari, Christina; Lederer, Carsten W; Santama, Niovi

    2016-01-01

    Katanins are microtubule (MT)-severing AAA proteins with high phylogenetic conservation throughout the eukaryotes. They have been functionally implicated in processes requiring MT remodeling, such as spindle assembly in mitosis and meiosis, assembly/disassembly of flagella and cilia and neuronal morphogenesis. Here, we uncover a novel family of katanin-like 2 proteins (KATNAL2) in mouse, consisting of five alternatively spliced isoforms encoded by the Katnal2 genomic locus. We further demonstrate that in vivo these isoforms are able to interact with themselves, with each other and moreover directly and independently with MRP/MinD-type P-loop NTPases Nubp1 and Nubp2, which are integral components of centrioles, negative regulators of ciliogenesis and implicated in centriole duplication in mammalian cells. We find KATNAL2 localized on interphase MTs, centrioles, mitotic spindle, midbody and the axoneme and basal body of sensory cilia in cultured murine cells. shRNAi of Katnal2 results in inefficient cytokinesis and severe phenotypes of enlarged cells and nuclei, increased numbers of centrioles and the manifestation of aberrant multipolar mitotic spindles, mitotic defects, chromosome bridges, multinuclearity, increased MT acetylation and an altered cell cycle pattern. Silencing or stable overexpression of KATNAL2 isoforms drastically reduces ciliogenesis. In conclusion, KATNAL2s are multitasking enzymes involved in the same cell type in critically important processes affecting cytokinesis, MT dynamics, and ciliogenesis and are also implicated in cell cycle progression.

  3. Activating omega-6 polyunsaturated fatty acids and inhibitory purine nucleotides are high affinity ligands for novel mitochondrial uncoupling proteins UCP2 and UCP3

    Czech Academy of Sciences Publication Activity Database

    Žáčková, Markéta; Škobisová, Eva; Urbánková, Eva; Ježek, Petr

    2003-01-01

    Roč. 278, č. 23 (2003), s. 20761-20769 ISSN 0021-9258 R&D Projects: GA AV ČR IAA5011106; GA ČR GA301/02/1215; GA MŠk ME 389 Institutional research plan: CEZ:AV0Z5011922 Keywords : uncoupling protein-2 * polyunsaturated fatty acids * recombinant yeast expression Subject RIV: CE - Biochemistry Impact factor: 6.482, year: 2003

  4. Nucleotide sequence, organization and expression of rdgA and rdgB genes that regulate pectin lyase production in the plant pathogenic bacterium Erwinia carotovora subsp. carotovora in response to DNA-damaging agents.

    Science.gov (United States)

    Liu, Y; Chatterjee, A; Chatterjee, A K

    1994-12-01

    In most soft-rotting Erwinia spp., including E. carotovora subsp. carotovora strain 71 (Ecc71), production of the plant cell wall degrading enzyme pectin lyase (Pnl) is activated by DNA-damaging agents such as mitomycin C (MC). Induction of Pnl production in Ecc71 requires a functional recA gene and the rdg locus. DNA sequencing and RNA analyses revealed that the rdg locus contains two regulatory genes, rdgA and rdgB, in separate transcriptional units. There is high homology between RdgA and repressors of lambdoid phages, specially phi 80. RdgB, however, has significant homology with transcriptional activators of Mu phage. Both RdgA and RdgB are also predicted to possess helix-turn-helix motifs. By replacing the rdgB promoter with the IPTG-inducible tac promoter, we have determined that rdgB by itself can activate Pnl production in Escherichia coli. However, deletion analysis of rdg+ DNA indicated that, when driven by their native promoters, functions of both rdgA and rdgB are required for the induction of pnlA expression by MC treatment. While rdgB transcription occurs only after MC treatment, a substantial level of rdgA mRNA is detected in the absence of MC treatment. Moreover, upon induction with MC, a new rdgA mRNA species, initiated from a different start site, is produced at a high level. Thus, the two closely linked rdgA and rdgB genes, required for the regulation of Pnl production, are expressed differently in Ecc71.

  5. The purine efflux pump PbuE in Bacillus subtilis modulates expression of the PurR and G-box (XptR) regulons by adjusting the purine base pool size

    DEFF Research Database (Denmark)

    Nygaard, P.; Saxild, Hans Henrik

    2005-01-01

    a functional PbuE pump. In a mutant defective in the metabolism of adenine, the ade apt mutant, we found a high intracellular level of adenine and constitutive high levels of PbuE. A growth test using a purine auxotroph provided further evidence for the role of PbuE in lowering the intracellular concentration...

  6. Regulation

    International Nuclear Information System (INIS)

    Ballereau, P.

    1999-01-01

    The different regulations relative to nuclear energy since the first of January 1999 are given here. Two points deserve to be noticed: the decree of the third august 1999 authorizing the national Agency for the radioactive waste management to install and exploit on the commune of Bures (Meuse) an underground laboratory destined to study the deep geological formations where could be stored the radioactive waste. The second point is about the uranium residues and the waste notion. The judgment of the administrative tribunal of Limoges ( 9. july 1998) forbidding the exploitation of a storage installation of depleted uranium considered as final waste and qualifying it as an industrial waste storage facility has been annulled bu the Court of Appeal. It stipulated that, according to the law number 75663 of the 15. july 1965, no criteria below can be applied to depleted uranium: production residue (possibility of an ulterior enrichment), abandonment of a personal property or simple intention to do it ( future use aimed in the authorization request made in the Prefecture). This judgment has devoted the primacy of the waste notion on this one of final waste. (N.C.)

  7. Effects of pH, temperature, and chemical structure on the stability of S-(purin-6-yl)-L-cysteine: evidence for a novel molecular rearrangement mechanism to yield N-(purin-6-yl)-L-cysteine.

    Science.gov (United States)

    Elfarra, A A; Hwang, I Y

    1996-01-01

    The stability of S-(purin-6-yl)-L-cysteine (SPC), a kidney-selective prodrug of 6-mercaptopurine and a putative metabolite of 6-chloropurine, was investigated under various pH and temperature conditions. At room temperature, the half-life (t 1/2) of SPC at either highly acidic (pH 3.6) or basic conditions (pH 9.6) was longer than at neutral or slightly acidic or basic conditions (pH 5.7-8.75). The primary degradation product, N-(purin-6-yl)-L-cysteine (NPC), was isolated using Sephadex LH-20 chromatography and characterized by 1H NMR and FAB/MS after derivatization with 2-iodoacetic acid. These results reveal novel stability requirements and implicate the cysteinyl amino group and the purinyl N-1 nitrogen in the mechanism of SPC rearrangement to NPC. Further evidence for this hypothesis was provided by the findings that the stability of SPC in phosphate buffer (pH 7.4) at 37 degrees C was similar to that of S-(guanin-6-yl)-L-cysteine, whereas S-(purin-6-yl)-N-acetyl-L-cysteine and S-(purin-6-yl)glutathione which have their cysteine amino groups blocked were much more stable than SPC. S-(Purin-6-yl)-L-homocysteine (SPHC) was also more stable than SPC, possibly because the formation of a 6-membered ring transition state as would be expected with SPHC is kinetically less favored than the formation of a 5-membered ring transition state as would be expected with SPC. These results may explain previous in vivo metabolism results of SPC and its analogs and may contribute to a better understanding of stability of structurally related cysteine S-conjugates.

  8. Subcellular location of the enzymes of purine breakdown in the yeast Candida famata grown on uric acid

    NARCIS (Netherlands)

    Large, Peter J.; Waterham, Hans R.; Veenhuis, Marten

    1990-01-01

    The subcellular location of the enzymes of purine breakdown in the yeast Candida famata, which grows on uric acid as sole carbon and nitrogen source, has been examined by subcellular fractionation methods. Uricase was confirmed as being peroxisomal, but the other three enzymes, allantoinase,

  9. The optimized microwave-assisted decomposition of formamides and its synthetic utility in the amination reactions of purines

    Czech Academy of Sciences Publication Activity Database

    Čechová, Lucie; Jansa, Petr; Šála, Michal; Dračínský, Martin; Holý, Antonín; Janeba, Zlatko

    2011-01-01

    Roč. 67, č. 5 (2011), s. 866-871 ISSN 0040-4020 R&D Projects: GA MŠk 1M0508; GA AV ČR KJB400550903 Institutional research plan: CEZ:AV0Z40550506 Keywords : microwave-assisted synthesis * DMF * formamides * dehalogenative amination * purines Subject RIV: CC - Organic Chemistry Impact factor: 3.025, year: 2011

  10. TD-DFT Investigation of the Magnetic Circular Dichroism Spectra of Some Purine and Pyrimidine Bases of Nucleic Acids

    DEFF Research Database (Denmark)

    Fahleson, Tobias; Kauczor, Joanna; Norman, Patrick

    2015-01-01

    We present a computational study of the magnetic circular dichroism (MCD) spectra in the 200–300 nm wavelength region of purine and its derivative hypoxanthine, as well as of the pyrimidine bases of nucleic acids uracil, thymine, and cytosine, using the B3LYP and CAM–B3LYP functionals. Solvent...

  11. Urinary purine derivatives as a tool to estimate dry matter intake in cattle: a meta-analysis

    Science.gov (United States)

    The objectives of this study were: 1) to investigate the relationship between dry matter intake (DMI) and urinary purine derivatives (PD) excretion in order to develop equations to predict DMI, and 2) to determine the endogenous excretion of PD for beef and dairy cattle using a meta-analytic approac...

  12. Consortium analysis of gene and gene–folate interactions in purine and pyrimidine metabolism pathways with ovarian carcinoma risk

    DEFF Research Database (Denmark)

    Kelemen, Linda E; Terry, Kathryn L; Goodman, Marc T

    2014-01-01

    SCOPE: We reevaluated previously reported associations between variants in pathways of one-carbon (1-C) (folate) transfer genes and ovarian carcinoma (OC) risk, and in related pathways of purine and pyrimidine metabolism, and assessed interactions with folate intake. METHODS AND RESULTS: Odds rat...

  13. TD-DFT investigation of the magnetic circular dichroism spectra of some purine and pyrimidine bases of nucleic acids.

    Science.gov (United States)

    Fahleson, Tobias; Kauczor, Joanna; Norman, Patrick; Santoro, Fabrizio; Improta, Roberto; Coriani, Sonia

    2015-05-28

    We present a computational study of the magnetic circular dichroism (MCD) spectra in the 200-300 nm wavelength region of purine and its derivative hypoxanthine, as well as of the pyrimidine bases of nucleic acids uracil, thymine, and cytosine, using the B3LYP and CAM-B3LYP functionals. Solvent effects are investigated within the polarizable continuum model and by inclusion of explicit water molecules. In general, the computed spectra are found to be in good agreement with the experimental ones, apart from some overall blue shifts. Both the pseudo-A term shape of the MCD spectra of the purines and the B term shape of the spectra of pyrimidine bases are reproduced. Our calculations also correctly reproduce the reversed phase of the MCD bands in purine compared to that of its derivatives present in nucleic acids. Solvent effects are sizable and system specific, but they do not in general alter the qualitative shape of the spectra. The bands are dominated by the bright π → π* transitions, and our calculations in solution nicely reproduce their energy differences, improving the estimates obtained in the gas phase. Shoulders are predicted for purine and uracil due to n → π* excitations, but they are too weak to be observed in the experiment.

  14. Synthesis of purines bearing functionalized C-substituents by the conjugate addition of nucleophiles to 6-vinylpurines and 6-ethynylpurines

    Czech Academy of Sciences Publication Activity Database

    Kuchař, Martin; Pohl, Radek; Votruba, Ivan; Hocek, Michal

    -, č. 22 (2006), s. 5083 -5098 ISSN 1434-193X R&D Projects: GA MŠk(CZ) 1M0508; GA AV ČR(CZ) 1QS400550501 Institutional research plan: CEZ:AV0Z40550506 Keywords : purines * Michael addition * conjugate additions * cross-coupling Subject RIV: CC - Organic Chemistry Impact factor: 2.769, year: 2006

  15. Nucleotide diversity and phylogenetic relationships among ...

    Indian Academy of Sciences (India)

    2017-03-03

    Mar 3, 2017 ... 2Department of Botany, D. S. B. Campus, Kumaun University, Nainital 263 001, India ... Rana T. S. 2017 Nucleotide diversity and phylogenetic relationships ... Anderson and Park 1989). ..... Edgewood Press, Edgewood, USA.

  16. Nucleotide excision repair in the test tube.

    NARCIS (Netherlands)

    N.G.J. Jaspers (Nicolaas); J.H.J. Hoeijmakers (Jan)

    1995-01-01

    textabstractThe eukaryotic nucleotide excision-repair pathway has been reconstituted in vitro, an achievement that should hasten the full enzymological characterization of this highly complex DNA-repair pathway.

  17. Urinary excretion of purine derivatives as an index of microbial protein synthesis in the camel (Camelus dromedarius).

    Science.gov (United States)

    Guerouali, Abdelhai; El Gass, Youssef; Balcells, Joaquim; Belenguer, Alvaro; Nolan, John

    2004-08-01

    Five experiments were carried out to extend knowledge of purine metabolism in the camel (Camelus dromedarius) and to establish a model to enable microbial protein outflow from the forestomachs to be estimated from the urinary excretion of purine derivatives (PD; i.e. xanthine, hypoxanthine, uric acid, allantoin). In experiment 1, four camels were fasted for five consecutive days to enable endogenous PD excretion in urine to be determined. Total PD excretion decreased during the fasting period to 267 (SE 41.5) micromol/kg body weight (W)0.75 per d. Allantoin and xanthine + hypoxanthine were consistently 86 and 6.1 % of total urinary PD during this period but uric acid increased from 3.6 % to 7.4 %. Xanthine oxidase activity in tissues (experiment 2) was (micromol/min per g fresh tissue) 0.038 in liver and 0.005 in gut mucosa but was not detected in plasma. In experiment 3, the duodenal supply of yeast containing exogenous purines produced a linear increase in urinary PD excretion rate with the slope indicating that 0.63 was excreted in urine. After taking account of endogenous PD excretion, the relationship can be used to predict purine outflow from the rumen. From the latter prediction, and also the purine:protein ratio in bacteria determined in experiment 5, we predicted the net microbial outflow from the rumen. In experiment 4, with increasing food intake, the rate of PD excretion in the urine increased linearly by about 11.1 mmol PD/kg digestible organic matter intake (DOMI), equivalent to 95 g microbial protein/kg DOMI.

  18. Prediction of rumen microbial outflow based on urinary excretion of purine derivatives

    International Nuclear Information System (INIS)

    Nolan, J.V.

    1999-01-01

    The method for predicting microbial protein outflow from the rumen based on the excretion of purine derivatives (PD) in the urine is being increasingly used by nutritionists. In contrast to methods that depend on estimates of digesta flow, the PD method does not require animals to be fitted surgically with cannulae into the gut, and studies can be performed with minimal disturbance to the experimental animals. Methods of analysis of PD have been improved and standardized. Certain assumptions, however, are required that could lead to errors when this method is used to predict microbial protein outflow from the rumen. The need for further investigation of these assumptions by means of isotopic tracers and other techniques is examined. (author)

  19. Modification of Purine and Pyrimidine Nucleosides by Direct C-H Bond Activation

    Directory of Open Access Journals (Sweden)

    Yong Liang

    2015-03-01

    Full Text Available Transition metal-catalyzed modifications of the activated heterocyclic bases of nucleosides as well as DNA or RNA fragments employing traditional cross-coupling methods have been well-established in nucleic acid chemistry. This review covers advances in the area of cross-coupling reactions in which nucleosides are functionalized via direct activation of the C8-H bond in purine and the C5-H or C6-H bond in uracil bases. The review focuses on Pd/Cu-catalyzed couplings between unactivated nucleoside bases with aryl halides. It also discusses cross-dehydrogenative arylations and alkenylations as well as other reactions used for modification of nucleoside bases that avoid the use of organometallic precursors and involve direct C-H bond activation in at least one substrate. The scope and efficiency of these coupling reactions along with some mechanistic considerations are discussed.

  20. Highly regioselective synthesis of undecylenic acid esters of purine nucleosides catalyzed by Candida antarctica lipase B.

    Science.gov (United States)

    Gao, Wen-Li; Li, Ning; Zong, Min-Hua

    2011-11-01

    Regioselective undecylenoylation of purine nucleosides as potential dual prodrugs was achieved by Candida antarctica lipase B using adenosine as a model reactant. The optimum organic solvent, molar ratio of vinyl ester to nucleoside, enzyme dosage, reaction temperature and molecular sieve amount were anhydrous THF, 5:1, 20 U/ml, 45°C and 75 mg/ml, respectively. Under the optimum conditions, the initial reaction rate, yield and 5'-regioselectivity were 1.1 mM/h, 90% and >99%, respectively. The enzymatic acylation of various nucleosides furnished the desired 5'-ester derivatives with the yields of 60-95% and 5'-regioselectivities of >99%. In addition, the lipase displayed excellent operational stability in THF, and retained 96% of its initial activity after reused for five batches.

  1. Inhibition and Structure of Trichomonas vaginalis Purine Nucleoside Phosphorylase with Picomolar Transition State Analogues

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldo-Matthis,A.; Wing, C.; Ghanem, M.; Deng, H.; Wu, P.; Gupta, A.; Tyler, P.; Evans, G.; Furneaux, R.; et al.

    2007-01-01

    Trichomonas vaginalis is a parasitic protozoan purine auxotroph possessing a unique purine salvage pathway consisting of a bacterial type purine nucleoside phosphorylase (PNP) and a purine nucleoside kinase. Thus, T. vaginalis PNP (TvPNP) functions in the reverse direction relative to the PNPs in other organisms. Immucillin-A (ImmA) and DADMe-Immucillin-A (DADMe-ImmA) are transition stte mimics of adenosine with geometric and electrostatic features that resemble early and late transition states of adenosine at the transition state stabilized by TvPNP. ImmA demonstrates slow-onset tight-binding inhibition with TvPNP, to give an equilibrium dissociation constant of 87 pM, an inhibitor release half-time of 17.2 min, and a K{sub m}/K{sub d} ratio of 70,100. DADMe-ImmA resembles a late ribooxacarbenium ion transition state for TvPNP to give a dissociation constant of 30 pM, an inhibitor release half-time of 64 min, and a K{sub m}/K{sub d} ratio of 203,300. The tight binding of DADMe-ImmA supports a late S{sub N}1 transition state. Despite their tight binding to TvPNP, ImmA and DADMe-ImmA are weak inhibitors of human and P. falciparum PNPs. The crystal structures of the TvPNP-ImmA{center_dot}PO{sub 4} and TvPNP{center_dot}DADMe-ImmA{center_dot}PO{sub 4} ternary complexes differ from previous structures with substrate anologues. The tight binding with DADMe-ImmA is in part due to a 2.7 {angstrom} ionic interaction between a PO{sub 4} oxygen and the N1 cation of the hydroxypyrrolidine and is weaker in the TvPNP{center_dot}ImmA{center_dot}PO{sub 4} structure at 3.5 {angstrom}. However, the TvPNP{center_dot}ImmA{center_dot}PO{sub 4} structure includes hydrogen bonds between the 2'-hydroxyl and the protein that are not present in TvPNP{center_dot}DADMe-ImmA{center_dot}PO{sub 4}. These structures explain why DADMe-ImmA binds tighter than ImmA. Immucillin-H is a 12 nM inhibitor of TvPNP but a 56 pM inhibitor of human PNP. And this difference is explained by isotope

  2. Measurements of purine derivatives and creatinine in spot urine samples of Chinese yellow cattle

    International Nuclear Information System (INIS)

    Xing, Z.; Xi, W.B.; Mo, F.; Liu, J.W.; Yang, Y.F.; Chen, X.B.

    2004-01-01

    An experiment was conducted using 18 Chinese Yellow Cattle located in 5 farms to study how supplementation of fermentable energy to low quality straw-based rations would improve rumen microbial protein synthesis. Within each farm, the animals were fed on five diets. Diets 1-2 were typical rice straw + by-products used by farmers and were low in fermentable energy content; Diets 3- 5 were more balanced, containing a higher content of fermentable energy. Purine derivatives (PD) and creatinine in spot urine samples were measured. The results showed that the PD to creatinine ratio was significantly higher with Diets 3-5 than with Diets 1-2. Organic matter digestibility and thus organic matter intake was also higher with Diets 3-5 compared to Diets 1-2. The results indicted that the efficiency of microbial protein synthesis could be improved by balancing the diet. (author)

  3. Purine nitrogen index, potentially a new parameter for rapid feed evaluation in ruminants

    International Nuclear Information System (INIS)

    Chen, X.B.; Oerskov, E.R.; Subba, D.B.; Jayasuriya, M.C.N.

    1999-01-01

    The concept of a new parameter 'Purine Nitrogen Index (PNI)' for feed evaluation in ruminants is discussed. PNI refers to the ratio of purine derivative (PD) nitrogen to total nitrogen in urine. It is suggested that PNI can potentially be used as an indicator of the efficiency with which degradable dietary nitrogen is converted to microbial protein in the rumen. The excretion of PD in the urine provides an estimation of the intestinal flow of microbial protein, and therefore, PNI effectively corresponds to the amount of microbial protein produced in the rumen relative to the nitrogen loss in the urine. If a diet or a dietary regime has a high conversion efficiency, proportionally more rumen degradable nitrogen is converted to microbial protein and less nitrogen is excreted in the urine, resulting in a high PNI. Conversely, if a diet has a poor conversion efficiency, proportionally less dietary nitrogen is converted to microbial protein and more is excreted in the urine, resulting in a low PNI. Preliminary data from six experiments involving 34 sheep confirmed a positive correlation between PNI and the nitrogen conversion efficiency, and suggested that a dietary regime with a PNI lower than 0.08 for sheep appeared to be a less efficient in the production of microbial protein and have a greater loss of nitrogen in the urine. PNI can theoretically be determined in spot urine samples, and has the potential to serve as a 'dipstick' method for the rapid evaluation of ruminant feeds. However, more research with a mathematical modelling approach is required to evaluate and develop the concept further. (author)

  4. One-electron oxidation reactions of purine and pyrimidine bases in cellular DNA.

    Science.gov (United States)

    Cadet, Jean; Wagner, J Richard; Shafirovich, Vladimir; Geacintov, Nicholas E

    2014-06-01

    The aim of this survey is to critically review the available information on one-electron oxidation reactions of nucleobases in cellular DNA with emphasis on damage induced through the transient generation of purine and pyrimidine radical cations. Since the indirect effect of ionizing radiation mediated by hydroxyl radical is predominant in cells, efforts have been made to selectively ionize bases using suitable one-electron oxidants that consist among others of high intensity UVC laser pulses. Thus, the main oxidation product in cellular DNA was found to be 8-oxo-7,8-dihydroguanine as a result of direct bi-photonic ionization of guanine bases and indirect formation of guanine radical cations through hole transfer reactions from other base radical cations. The formation of 8-oxo-7,8-dihydroguanine and other purine and pyrimidine degradation products was rationalized in terms of the initial generation of related radical cations followed by either hydration or deprotonation reactions in agreement with mechanistic pathways inferred from detailed mechanistic studies. The guanine radical cation has been shown to be implicated in three other nucleophilic additions that give rise to DNA-protein and DNA-DNA cross-links in model systems. Evidence was recently provided for the occurrence of these three reactions in cellular DNA. There is growing evidence that one-electron oxidation reactions of nucleobases whose mechanisms have been characterized in model studies involving aqueous solutions take place in a similar way in cells. It may also be pointed out that the above cross-linked lesions are only produced from the guanine radical cation and may be considered as diagnostic products of the direct effect of ionizing radiation.

  5. Purine nitrogen index, potentially a new parameter for rapid feed evaluation in ruminants

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X B; Oerskov, E R [Rowett Research Institute, Bucksburn, Aberdeen (United Kingdom); Subba, D B [Pakhribas Agricultural Centre, Dhankuta, Kathmandu (Nepal); Jayasuriya, M C.N. [International Atomic Energy Agency, Animal Production and Health Section, Vienna (Austria)

    1999-06-01

    The concept of a new parameter `Purine Nitrogen Index (PNI)` for feed evaluation in ruminants is discussed. PNI refers to the ratio of purine derivative (PD) nitrogen to total nitrogen in urine. It is suggested that PNI can potentially be used as an indicator of the efficiency with which degradable dietary nitrogen is converted to microbial protein in the rumen. The excretion of PD in the urine provides an estimation of the intestinal flow of microbial protein, and therefore, PNI effectively corresponds to the amount of microbial protein produced in the rumen relative to the nitrogen loss in the urine. If a diet or a dietary regime has a high conversion efficiency, proportionally more rumen degradable nitrogen is converted to microbial protein and less nitrogen is excreted in the urine, resulting in a high PNI. Conversely, if a diet has a poor conversion efficiency, proportionally less dietary nitrogen is converted to microbial protein and more is excreted in the urine, resulting in a low PNI. Preliminary data from six experiments involving 34 sheep confirmed a positive correlation between PNI and the nitrogen conversion efficiency, and suggested that a dietary regime with a PNI lower than 0.08 for sheep appeared to be a less efficient in the production of microbial protein and have a greater loss of nitrogen in the urine. PNI can theoretically be determined in spot urine samples, and has the potential to serve as a `dipstick` method for the rapid evaluation of ruminant feeds. However, more research with a mathematical modelling approach is required to evaluate and develop the concept further. (author) 15 refs, 5 figs, 4 tabs

  6. Catalase increases ethanol oxidation through the purine catabolism in rat liver.

    Science.gov (United States)

    Villalobos-García, Daniel; Hernández-Muñoz, Rolando

    2017-08-01

    Hepatic ethanol oxidation increases according to its concentration and is raised to near-saturation levels of alcohol dehydrogenase (ADH); therefore, re-oxidation of NADH becomes rate limiting in ethanol metabolism by the liver. Adenosine is able to increase liver ethanol oxidation in both in vivo and in vitro conditions; the enhancement being related with the capacity of the nucleoside to accelerate the transport of cytoplasmic reducing equivalents to mitochondria, by modifying the subcellular distribution of the malate-aspartate shuttle components. In the present study, we explored the putative effects of adenosine and other purines on liver ethanol oxidation mediated by non-ADH pathways. Using the model of high precision-cut rat liver slices, a pronounced increase of ethanol oxidation was found in liver slices incubated with various intermediates of the purine degradation pathway, from adenosine to uric acid (175-230%, over controls). Of these, urate had the strongest (230%), whereas xanthine had the less pronounced effect (178% over controls). The enhancement was not abolished by 4-methylpyrazole, indicating that the effect was independent of alcohol dehydrogenase. Conversely, aminotriazole, a catalase inhibitor, completely abolished the effect, pointing out that this enhanced ethanol oxidation is mediated by catalase activity. It is concluded that the H 2 O 2 needed for catalase activity is derived from the oxidation of (hypo)xanthine by xanthine oxidase and the oxidation of urate by uricase. The present and previous data led us to propose that, depending on the metabolic conditions, adenosine might be able to stimulate the metabolism of ethanol through different pathways. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Efecto antagónico in vitro de actinomicetos aislados de purines de chipaca (bidens pilosa l.) frente a phytophthora infestans (mont) de bary

    OpenAIRE

    Fonseca Ardila, Yudy Astrid; Castellanos Suárez, Diana Edith; León Sicard, Tomás Enrique

    2011-01-01

    Se estudió el efecto inhibidor de los actinomicetos presentes en purines o extractos fermentados de plantas de chipaca (Bidens pilosa L.), sobre el crecimiento de Phytophthora infestans (Mont) de Bary, causante del tizón tardío de la papa. Se elaboraron cuatro purines de flores, raíces, hojas-tallos y su mezcla. De estos purines se obtuvieron 25 aislamientos de actinomicetos, cada uno de los cuales se enfrentó con P. infestans en placas de medio de cultivo, utilizando la técnica de anillos de...

  8. Tools and drugs for uracil nucleotide-activated P2Y receptors.

    Science.gov (United States)

    Rafehi, Muhammad; Müller, Christa E

    2018-04-13

    P2Y receptors (P2YRs) are a family of G protein-coupled receptors activated by extracellular nucleotides. Physiological P2YR agonists include purine and pyrimidine nucleoside di- and triphosphates, such as ATP, ADP, UTP, UDP, nucleotide sugars, and dinucleotides. Eight subtypes exist, P2Y 1 , P2Y 2 , P2Y 4 , P2Y 6 , P2Y 11 , P2Y 12 , P2Y 13 , and P2Y 14 , which represent current or potential future drug targets. Here we provide a comprehensive overview of ligands for the subgroup of the P2YR family that is activated by uracil nucleotides: P2Y 2 (UTP, also ATP and dinucleotides), P2Y 4 (UTP), P2Y 6 (UDP), and P2Y 14 (UDP, UDP-glucose, UDP-galactose). The physiological agonists are metabolically unstable due to their fast hydrolysis by ectonucleotidases. A number of agonists with increased potency, subtype-selectivity and/or enzymatic stability have been developed in recent years. Useful P2Y 2 R agonists include MRS2698 (6-01, highly selective) and PSB-1114 (6-05, increased metabolic stability). A potent and selective P2Y 2 R antagonist is AR-C118925 (10-01). For studies of the P2Y 4 R, MRS4062 (3-15) may be used as a selective agonist, while PSB-16133 (10-06) represents a selective antagonist. Several potent P2Y 6 R agonists have been developed including 5-methoxyuridine 5'-O-((R p )α-boranodiphosphate) (6-12), PSB-0474 (3-11), and MRS2693 (3-26). The isocyanate MRS2578 (10-08) is used as a selective P2Y 6 R antagonist, although its reactivity and low water-solubility are limiting. With MRS2905 (6-08), a potent and metabolically stable P2Y 14 R agonist is available, while PPTN (10-14) represents a potent and selective P2Y 14 R antagonist. The radioligand [ 3 H]UDP can be used to label P2Y 14 Rs. In addition, several fluorescent probes have been developed. Uracil nucleotide-activated P2YRs show great potential as drug targets, especially in inflammation, cancer, cardiovascular and neurodegenerative diseases. Copyright © 2018. Published by Elsevier Inc.

  9. A Nucleotide Phosphatase Activity in the Nucleotide Binding Domain of an Orphan Resistance Protein from Rice*

    Science.gov (United States)

    Fenyk, Stepan; de San Eustaquio Campillo, Alba; Pohl, Ehmke; Hussey, Patrick J.; Cann, Martin J.

    2012-01-01

    Plant resistance proteins (R-proteins) are key components of the plant immune system activated in response to a plethora of different pathogens. R-proteins are P-loop NTPase superfamily members, and current models describe their main function as ATPases in defense signaling pathways. Here we show that a subset of R-proteins have evolved a new function to combat pathogen infection. This subset of R-proteins possesses a nucleotide phosphatase activity in the nucleotide-binding domain. Related R-proteins that fall in the same phylogenetic clade all show the same nucleotide phosphatase activity indicating a conserved function within at least a subset of R-proteins. R-protein nucleotide phosphatases catalyze the production of nucleoside from nucleotide with the nucleotide monophosphate as the preferred substrate. Mutation of conserved catalytic residues substantially reduced activity consistent with the biochemistry of P-loop NTPases. Kinetic analysis, analytical gel filtration, and chemical cross-linking demonstrated that the nucleotide-binding domain was active as a multimer. Nuclear magnetic resonance and nucleotide analogues identified the terminal phosphate bond as the target of a reaction that utilized a metal-mediated nucleophilic attack by water on the phosphoester. In conclusion, we have identified a group of R-proteins with a unique function. This biochemical activity appears to have co-evolved with plants in signaling pathways designed to resist pathogen attack. PMID:22157756

  10. A nucleotide phosphatase activity in the nucleotide binding domain of an orphan resistance protein from rice.

    Science.gov (United States)

    Fenyk, Stepan; Campillo, Alba de San Eustaquio; Pohl, Ehmke; Hussey, Patrick J; Cann, Martin J

    2012-02-03

    Plant resistance proteins (R-proteins) are key components of the plant immune system activated in response to a plethora of different pathogens. R-proteins are P-loop NTPase superfamily members, and current models describe their main function as ATPases in defense signaling pathways. Here we show that a subset of R-proteins have evolved a new function to combat pathogen infection. This subset of R-proteins possesses a nucleotide phosphatase activity in the nucleotide-binding domain. Related R-proteins that fall in the same phylogenetic clade all show the same nucleotide phosphatase activity indicating a conserved function within at least a subset of R-proteins. R-protein nucleotide phosphatases catalyze the production of nucleoside from nucleotide with the nucleotide monophosphate as the preferred substrate. Mutation of conserved catalytic residues substantially reduced activity consistent with the biochemistry of P-loop NTPases. Kinetic analysis, analytical gel filtration, and chemical cross-linking demonstrated that the nucleotide-binding domain was active as a multimer. Nuclear magnetic resonance and nucleotide analogues identified the terminal phosphate bond as the target of a reaction that utilized a metal-mediated nucleophilic attack by water on the phosphoester. In conclusion, we have identified a group of R-proteins with a unique function. This biochemical activity appears to have co-evolved with plants in signaling pathways designed to resist pathogen attack.

  11. Optimization of the operation of separation of the solids in suspension of the purines (Part I); Optimizacion de la operacion de separacion de los solidos en suspension de los purines (Parte I)

    Energy Technology Data Exchange (ETDEWEB)

    Bosque Hernandez, J. L. del; Martin Sanchez, J. L.

    2004-07-01

    The swinish cattle raising you can calculate in our country m 18 million heads. Locating the Spanish cattle cabin in the second position of the European Union. This sector is of great importance in the economy, having big possibilities of growth, due to the great existent demand. However, the generated residuals, denominated purines, they suppose a great obstacle for the expansion of this sector. The purines mammoth production and other cattle residuals outline a serious problem of environmental contamination; for what is necessary to establish the approaches for an appropriate treatment of the same ones, with the purpose of achieving the elimination of the problems of environmental contamination that you/they generate and, in special way, those contamination of the waters. (Author) 5 refs.

  12. Substituent and noncovalent interaction effects in the reactivity of purine derivatives with tetracarboxylato-dirhodium(II) units. Rationalization of a rare binding mode via N3.

    Science.gov (United States)

    Amo-Ochoa, Pilar; Castillo, Oscar; Harrington, Ross W; Zamora, Félix; Houlton, Andrew

    2013-02-18

    Reactions between [Rh(2)(CH(3)COO)(4)] with 2,6-diaminopurine (HDap) or 6-chloro-2-aminopurine (HClap) and [Rh(2)((CH(3))(3)CCOO)(4)] with HClap produce, three new dirhodium(II) carboxylate complexes of the general form, [Rh(2)(RCOO)(4)(Purine)(2)] (R = CH(3), (CH(3))(3)C). Single crystal X-ray diffraction studies confirm that in all cases the purine coordinates to the axial position of the dirhodium(II)tetracarboxylate unit. However, while the complex obtained with HDap features the typical purine binding mode via N(7), complexes containing HClap show unusual N3 coordination. This is an extremely rare instance of an unrestricted purine binding via N3. Some rationalization of these data is offered based on a series of DFT calculations.

  13. Nucleobases, nucleosides, and nucleotides: versatile biomolecules for generating functional nanomaterials.

    Science.gov (United States)

    Pu, Fang; Ren, Jinsong; Qu, Xiaogang

    2018-02-21

    The incorporation of biomolecules into nanomaterials generates functional nanosystems with novel and advanced properties, presenting great potential for applications in various fields. Nucleobases, nucleosides and nucleotides, as building blocks of nucleic acids and biological coenzymes, constitute necessary components of the foundation of life. In recent years, as versatile biomolecules for the construction or regulation of functional nanomaterials, they have stimulated interest in researchers, due to their unique properties such as structural diversity, multiplex binding sites, self-assembly ability, stability, biocompatibility, and chirality. In this review, strategies for the synthesis of nanomaterials and the regulation of their morphologies and functions using nucleobases, nucleosides, and nucleotides as building blocks, templates or modulators are summarized alongside selected applications. The diverse applications range from sensing, bioimaging, and drug delivery to mimicking light-harvesting antenna, the construction of logic gates, and beyond. Furthermore, some perspectives and challenges in this emerging field are proposed. This review is directed toward the broader scientific community interested in biomolecule-based functional nanomaterials.

  14. Purine salvage in the apicomplexan Sarcocystis neurona, and generation of hypoxanthine-xanthine-guanine phosphoribosyltransferase-deficient clones for positive-negative selection of transgenic parasites.

    Science.gov (United States)

    Dangoudoubiyam, Sriveny; Zhang, Zijing; Howe, Daniel K

    2014-09-01

    Sarcocystis neurona is an apicomplexan parasite that causes severe neurological disease in horses and marine mammals. The Apicomplexa are all obligate intracellular parasites that lack purine biosynthesis pathways and rely on the host cell for their purine requirements. Hypoxanthine-xanthine-guanine phosphoribosyltransferase (HXGPRT) and adenosine kinase (AK) are key enzymes that function in two complementary purine salvage pathways in apicomplexans. Bioinformatic searches of the S. neurona genome revealed genes encoding HXGPRT, AK and all of the major purine salvage enzymes except purine nucleoside phosphorylase. Wild-type S. neurona were able to grow in the presence of mycophenolic acid (MPA) but were inhibited by 6-thioxanthine (6-TX), suggesting that the pathways involving either HXGPRT or AK are functional in this parasite. Prior work with Toxoplasma gondii demonstrated the utility of HXGPRT as a positive-negative selection marker. To enable the use of HXGPRT in S. neurona, the SnHXGPRT gene sequence was determined and a gene-targeting plasmid was transfected into S. neurona. SnHXGPRT-deficient mutants were selected with 6-TX, and single-cell clones were obtained. These Sn∆HXG parasites were susceptible to MPA and could be complemented using the heterologous T. gondii HXGPRT gene. In summary, S. neurona possesses both purine salvage pathways described in apicomplexans, thus allowing the use of HXGPRT as a positive-negative drug selection marker in this parasite.

  15. Trisubstituted purine inhibitors of PDGFR alpha and their antileukemic activity in the human eosinophilic cell line EOL-1

    Czech Academy of Sciences Publication Activity Database

    Malínková, Veronika; Řezníčková, Eva; Jorda, Radek; Gucký, T.; Kryštof, Vladimír

    2017-01-01

    Roč. 25, č. 24 (2017), s. 6523-6535 ISSN 0968-0896 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : dependent kinase inhibitors * src tyrosine kinase * 2,6,9-trisubstituted purines * therapeutic target * potent inhibitor * imatinib * leukemia * mutations * mutant * domain Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Hematology Impact factor: 2.930, year: 2016

  16. Study of copper and purine-copper complexes on modified carbon electrodes by cyclic and elimination voltammetry

    Czech Academy of Sciences Publication Activity Database

    Trnková, L.; Zerzánková, L.; Dyčka, F.; Mikelová, R.; Jelen, František

    2008-01-01

    Roč. 8, č. 1 (2008), s. 429-444 ISSN 1424-8220 R&D Projects: GA AV ČR(CZ) IAA100040602; GA AV ČR(CZ) IAA400040804 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : copper-purine complexes * paraffin-impregnated graphite electrode * mercury-film electrode Subject RIV: BO - Biophysics Impact factor: 1.870, year: 2008

  17. Distribution coefficients of purine alkaloids in water-ammonium sulfate-alkyl acetate-dialkyl phthalate systems

    Science.gov (United States)

    Korenman, Ya. I.; Krivosheeva, O. A.; Mokshina, N. Ya.

    2012-12-01

    The distribution of purine alkaloids (caffeine, theobromine, theophylline) was studied in the systems: alkyl acetates-dialkyl phtalate-salting-out agent (ammonium sulfate). The quantitative characteristics of the extraction-distribution coefficients ( D) and the degree of extraction ( R, %) are calculated. The relationships between the distribution coefficients of alkaloids and the length of the hydrocarbon radical in the molecule of alkyl acetate (dialkyl phtalate) are determined. The possibility of predicting the distribution coefficients is demonstrated.

  18. Synthesis of some glycoside analogs and related compounds from 9-amino-6-(methylthio)-9H-purine.

    Science.gov (United States)

    Temple, C; Kussner, C L; Montgomery, J A

    1975-12-01

    Additional information on the anticancer activity of 9-amino-9H-purine-6(1H)-thione and its derivatives was sought by the synthesis of some 9-(substituted amino)-6-(methylthio)-9H-purines in which the 9-substituent contained functional groups capable of either reversible or irreversible binding with an enzymatic site. Condensation of 9-amino-6-(methylthio)-9H-purine (1) with some carbonyl compounds followed by hydride reduction of the azomethine linkage in the intermediates leads to the 2-pyrrolylmethyl (8), 2,3,4-trihydroxybutyl (10), and the 1,5-dihydroxy-2- and 3-pentyl (11 and 12) compounds. A 4-hydroxybutyl derivative (13) was obtained by alkylation of 18, the 9-acetyl derivative of 1, with 4-chlorobutyl acetate followed by saponification. The cyclization of 13 and 11 with a sulfonyl chloride gave the 9-pyrrolidin-1-yl (27) and the 9-[2-(tosyloxymethyl)pyrrolidin-1-yl] (28), respectively. Acylation of 1 with ethyl L-2-pyrrolidine-5-carboxylate and ethyl 1-methyl-5-pyrrolidone-3-carboxylate, respectively, in Me2SO containing NaH gave the corresponding amides 15 and 17. Alkylation of 18 with 1-bromo-2-chloroethane and epichlorohydrin gave the N-(2-chloroethyl) and N-(1,2-epoxy-3-propyl) derivatives 19 and 20. The chloro group of the chlorobutyl derivative of 18 was displaced with KSCN and NaN3, respectively, to give the thiocyanate and azido derivatives 23 and 24. Hydrogenation of the latter gave the amine (25), which was acylated with ethyl chloroformate to give the (ethoxycarbonyl)amino compound 26. None of these compounds showed activity against L1210 leukemia cells implanted ip in mice on a single-dose schedule, suggesting that the activity observed in the simpler 9-aminopurines resulted from cleavage of the hydrazino linkage to give pH-purine-6(1H)-thione.

  19. Kinetics and mechanism of carbon-8 methylation of purine bases and nucleosides by methyl radical

    International Nuclear Information System (INIS)

    Zady, M.F.; Wong, J.L.

    1977-01-01

    The kinetics of homolytic methylation of the model purine compound caffeine at carbon-8 were determined as a function of several reaction variables. The methyl radical was generated from tert-butyl peracetate (BPA) either thermally (65 to 95 0 C) or photochemically (greater than 300 nm, 25 0 C). The thermal reaction k (25 0 C) was found to be 3.09 x 10 -8 s -1 from the linear log k (pseudo-first-order) vs. l/T plot. The light reactions using the 450- and 1200-W mercury lamps proceeded with k (25 0 C) 450- and 2160-fold greater, respectively. The derived activation energies are consistent with an S/sub E/Ar reaction. Increasing the concentration of caffeine from 0.25 M to 1.67 M in the presence of 3 molar equiv of BPA did not cause any side reaction. The pH-rate profile can be predicted by rate equations, which are derived on the basis of an electrophilic substitution occurring on the free base and conjugate acid of a heteroaromatic system. A competition study using tetrahydrofuran reveals the presence of a radical sigma complex IIIa and a charge transfer complex IIIb as intermediates for methylation under neutral and acidic conditions, respectively. Their rate-determining nature was indicated by the small positive kinetic isotope effect and the inverse solvent isotope effects: k/sub H 3 O + //k/sub D 3 O + / = 0.87 and k/sub H 2 O//k/sub D 2 O/ = 0.32. Thus, in acidic medium, a preequilibrium proton transfer to form the caffeine conjugate acid precedes the rate-controlling formation of IIIb. In neutral solution, the rate-determining step appears to be the protonation of the radical nitrogen in IIIa converting it to III. The acid-catalyzed caffeine-BPA reaction was shown to be general for other purines such as adenine, adenosine, guanine, guanosine, hypoxanthine, and inosine

  20. Synthesis of modified oligonucleotides that contain purine and pyrimidine radio-induced base lesions

    International Nuclear Information System (INIS)

    Romieu, Anthony

    1999-01-01

    Different factors as oxidizing or carcinogenesis agents, UV and ionizing radiations,.... can generate a wide, spectrum of DNA base damages. In order to study the biochemical and structural features of these DNA damages, it is important to prepare short DNA fragments (20 to 50 bases long) bearing a single or several modifications at specific sites in their sequences. The chemical synthesis is a powerful tool to prepare such modified DNA fragments. This work focusses on the chemical incorporation of several modified nucleosides formed in DNA by ionizing radiations or by photo-sensitization. The first part of this study describes the preparation of a phosphoramidite synthon of 5-hydroxy-2'-deoxyuridine and its subsequent incorporation into synthetic oligonucleotides ranging from 14 to 33 bases long. In a second part (chapters Ill and IV), the synthesis and incorporation of original radiation-induced tandem lesions: the carbon-bridged cyclo-nucleosides are presented. Both (5'R)- and (5'S) diastereomers of 5',8-cyclo-2'-deoxyadenosine and 5',8-cyclo-2'-deoxyguanosine have been individually inserted into various different oligonucleotides (3 to 22 bases long) by using the standard phosphoramidite chemistry. The chemical incorporation of a pyrimidine analogue: (5'S, 6S)-5',6-cyclo-5,6-dihydro-thymidine has been also achieved. The loss of aromaticity of this modified nucleoside and its poor reactivity required the development of a synthetic strategy entirely different from that used for the preparation and subsequent incorporation of the phosphoramidite synthons of 5',8-cyclo-purine-2'-deoxyribo-nucleosides. The third part of this study deals with the synthesis of a phosphoramidite synthon of 4-hydroxy-8-oxo-4,8-dihydro-2'-deoxyguanosine. The two (4R)- and (4S)- diastereomers of this oxidized purine have been separated and individually inserted in several synthetic DNA fragments. No epimerization of C-4 position was observed during the solid-phase synthesis and during the

  1. Altered Mitochondria, Protein Synthesis Machinery, and Purine Metabolism Are Molecular Contributors to the Pathogenesis of Creutzfeldt-Jakob Disease.

    Science.gov (United States)

    Ansoleaga, Belén; Garcia-Esparcia, Paula; Llorens, Franc; Hernández-Ortega, Karina; Carmona Tech, Margarita; Antonio Del Rio, José; Zerr, Inga; Ferrer, Isidro

    2016-06-12

    Neuron loss, synaptic decline, and spongiform change are the hallmarks of sporadic Creutzfeldt-Jakob disease (sCJD), and may be related to deficiencies in mitochondria, energy metabolism, and protein synthesis. To investigate these relationships, we determined the expression levels of genes encoding subunits of the 5 protein complexes of the electron transport chain, proteins involved in energy metabolism, nucleolar and ribosomal proteins, and enzymes of purine metabolism in frontal cortex samples from 15 cases of sCJD MM1 and age-matched controls. We also assessed the protein expression levels of subunits of the respiratory chain, initiation and elongation translation factors of protein synthesis, and localization of selected mitochondrial components. We identified marked, generalized alterations of mRNA and protein expression of most subunits of all 5 mitochondrial respiratory chain complexes in sCJD cases. Expression of molecules involved in protein synthesis and purine metabolism were also altered in sCJD. These findings point to altered mRNA and protein expression of components of mitochondria, protein synthesis machinery, and purine metabolism as components of the pathogenesis of CJD. © 2016 American Association of Neuropathologists, Inc. All rights reserved.

  2. Adaptive evolution to a high purine and fat diet of carnivorans revealed by gut microbiomes and host genomes.

    Science.gov (United States)

    Zhu, Lifeng; Wu, Qi; Deng, Cao; Zhang, Mengjie; Zhang, Chenglin; Chen, Hua; Lu, Guoqing; Wei, Fuwen

    2018-05-01

    Carnivorous members of the Carnivora reside at the apex of food chains and consume meat-only diets, rich in purine, fats and protein. Here, we aimed to identify potential adaptive evolutionary signatures compatible with high purine and fat metabolism based on analysis of host genomes and symbiotic gut microbial metagenomes. We found that the gut microbiomes of carnivorous Carnivora (e.g., Felidae, Canidae) clustered in the same clade, and other clades comprised omnivorous and herbivorous Carnivora (e.g., badgers, bears and pandas). The relative proportions of genes encoding enzymes involved in uric acid degradation were higher in the gut microbiomes of meat-eating carnivorans than plant-eating species. Adaptive amino acid substitutions in two enzymes, carnitine O-palmitoyltransferase 1 (CPT1A) and lipase F (LIPF), which play a role in fat digestion, were identified in Felidae-Candidae species. Carnivorous carnivorans appear to endure diets high in purines and fats via gut microbiomic and genomic adaptations. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Flow of nucleic acids from the rumen and recovery of purine derivatives in the urine of cattle and buffaloes

    International Nuclear Information System (INIS)

    Soejono, M.; Yusiati, L.M.; Bachrudin, Z.; Budhi, S.P.S.; Widyobroto, B.P.; Utomo, R.

    2004-01-01

    An experiment was conducted to determine the flow of nucleic acids from the rumen to duodenum. Two duodenal-cannulated each of male Ongole cattle and buffaloes aged three to four years were used and fed a mixture of king grass and rice bran (70:30 DM basis). At 95% and 60% of the voluntary intake in three weeks each before morning feeding period. Cr-mordanted alfalfa was used as a marker. The excretion of allantoin, uric acid, purine derivatives, and creatinine and the PDC index were higher in cattle than buffaloes at both levels of intake (P < 0.05). There were no difference between cattle and buffaloes with regard to the flow of RNA when expressed on digestible organic matter intake (DOMI), flow rate of RNA/kg DOMI, or flow rate of crude protein/kg DOMI. It can be concluded that the differences in urine excretion of purine derivatives between cattle and buffalo is not due to the differences in the amount of rumen microbial protein synthesis, but due to differences in purine metabolism between cattle and buffaloes. (author)

  4. Regio- and Enantioselective N-Allylations of Imidazole, Benzimidazole, and Purine Heterocycles Catalyzed by Single-Component Metallacyclic Iridium Complexes

    Science.gov (United States)

    Stanley, Levi M.

    2010-01-01

    Highly regio- and enantioselective iridium-catalyzed N-allylations of benzimidazoles, imidazoles, and purines have been developed. N-Allylated benzimidazoles and imidazoles were isolated in high yields (up to 97%) with high branched-to-linear selectivity (up to 99:1) and enantioselectivity (up to 98% ee) from the reactions of benzimidazole and imidazole nucleophiles with unsymmetrical allylic carbonates in the presence of single component, ethylene-bound, metallacyclic iridium catalysts. N-Allylated purines were also obtained in high yields (up to 91%) with high N9:N7 selectivity (up to 96:4), high branched-to-linear selectivity (98:2), and high enantioselectivity (up to 98% ee) under similar conditions. The reactions encompass a range of benzimidazole, imidazole, and purine nucleophiles, as well as a variety of unsymmetrical aryl, heteroaryl, and aliphatic allylic carbonates. Competition experiments between common amine nucleophiles and the heterocyclic nitrogen nucleophiles studied in this work illustrate the effect of nucleophile pKa on the rate of iridium-catalyzed N-allylation reactions. Kinetic studies on the allylation of benzimidazole catalyzed by metallacyclic iridium-phosphoramidite complexes, in combination with studies on the deactivation of these catalysts in the presence of heterocyclic nucleophiles, provide insight into the effects of the structure of the phosphoramidite ligands on the stability of the metallacyclic catalysts. The data obtained from these studies has led to the development of N-allylations of benzimidazoles and imidazoles in the absence of an exogenous base. PMID:19480431

  5. Studies on the energy metabolism of opossum (Didelphis virginiana) erythrocytes: V. Utilization of hypoxanthine for the synthesis of adenine and guanine nucleotides in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Bethlenfalvay, N.C.; White, J.C.; Chadwick, E.; Lima, J.E. (Fitzsimons Army Medical Center, Aurora, CO (USA))

    1990-06-01

    High pressure liquid radiochromatography was used to test the ability of opossum erythrocytes to incorporate tracer amounts of (G-{sup 3}H) hypoxanthine (Hy) into ({sup 3}H) labelled triphosphates of adenine and guanine. In the presence of supraphysiologic (30 mM) phosphate which is optimal for PRPP synthesis, both ATP and GTP are extensively labelled. When physiologic (1 mM) medium phosphate is used, red cells incubated under an atmosphere of nitrogen accumulate ({sup 3}H) ATP in a linear fashion suggesting ongoing PRPP synthesis in red cells whose hemoglobin is deoxygenated. In contrast, a lesser increase of labelled ATP is observed in cells incubated under oxygen, suggesting that conditions for purine nucleotide formation from ambient Hy are more favorable in the venous circulation.

  6. Studies on the energy metabolism of opossum (Didelphis virginiana) erythrocytes: V. Utilization of hypoxanthine for the synthesis of adenine and guanine nucleotides in vitro

    International Nuclear Information System (INIS)

    Bethlenfalvay, N.C.; White, J.C.; Chadwick, E.; Lima, J.E.

    1990-01-01

    High pressure liquid radiochromatography was used to test the ability of opossum erythrocytes to incorporate tracer amounts of [G- 3 H] hypoxanthine (Hy) into [ 3 H] labelled triphosphates of adenine and guanine. In the presence of supraphysiologic (30 mM) phosphate which is optimal for PRPP synthesis, both ATP and GTP are extensively labelled. When physiologic (1 mM) medium phosphate is used, red cells incubated under an atmosphere of nitrogen accumulate [ 3 H] ATP in a linear fashion suggesting ongoing PRPP synthesis in red cells whose hemoglobin is deoxygenated. In contrast, a lesser increase of labelled ATP is observed in cells incubated under oxygen, suggesting that conditions for purine nucleotide formation from ambient Hy are more favorable in the venous circulation

  7. Effect of root application of 6-benzylamine purine on auxin transport in Malus domestica

    International Nuclear Information System (INIS)

    Stutte, G.

    1987-01-01

    The effect of 6-benzylamine purine (BA) on movement of napthalene acetic acid (NAA) applied to the shoot was investigated. Three-month-old York apple seedlings in sand culture were placed under mercury halide lamps (285 μmol m -2 s -1 ) at 22 0 C for 24 hours; then 13.8, 27.5 or 55 μMol of BA was applied as a soil drench. [ 14 C]-NAA was injected into the shoot at petiole base of 4th mature leaf. After 24 hours plants were harvested and movement of label acropetally to new shoot growth and basipetally to old shoot growth or roots determined. Seventeen (S.E. 3.3) percent of applied label was recovered away from application site. In controls, 67% of 14 C that moved was recovered from new shoot growth, 9% in roots and 24% in old shoot tissue. The 13.8 μMol treatment resulted in 37% of label being recovered in root tissue and 48% in new growth. The 27.5 and 55 μMol applications increased the amount recovered in old shoot tissue but did not increase labelling of root tissues

  8. The antibacterial activity and toxicity of enrofloxacin are decreased by nanocellulose conjugated with aminobenzyl purin.

    Science.gov (United States)

    Yasini, Seyed Ali; Zadeh, Mohammad Hossein Balal; Shahdadi, Hossein

    2015-11-01

    The first aim of this study was to synthesize nanocellulose conjugated with aminobenzyl purin (NCABP), and the second aim was to evaluate the effect of NCABP on both toxicity and antibacterial activity of enrofloxacin. Here, the adsorption of enrofloxacin by NCABP was first modeled by molecular dynamic (MD) simulation. In the next step, NCABP was synthesized, and was exposed to enrofloxacin, 1000 μg mL(-1), at various conditions. Then, the quantity of adsorption and release was separately measured. Furthermore, both toxicity and antibacterial activity of NCABP, enrofloxacin, and (NCABP+enrofloxacin) were separately evaluated. In this study, MD simulation clearly showed the adsorption after 50 picoseconds. The adsorption tests revealed that the increase of incubation time and NCABP concentration, at range of 50-200 μg mL(-1), led to increase of adsorption. Moreover, the decrease of pH led to increase of adsorption. Interestingly, NCABP could adsorb enrofloxacin, up to 1000 μg mL(-1), in different types of meat. Moreover, the increase of incubation time and temperature did not release enrofloxacin, but the increase of pH increased release. This study showed that both toxicity and antibacterial activity of enrofloxacin were decreased when exposed together with NCABP. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Effect of Purine Nucleoside Analogue-Acyclovir on The Sperm Parameters and Testosterone Production in Rats

    Directory of Open Access Journals (Sweden)

    Vahid Nejati

    2013-01-01

    Full Text Available Background: Acyclovir (ACV, a synthetic purine nucleoside analogue derived fromguanosine, is known to be toxic to gonads and the aim of this study was to evaluate theeffect of ACV on the sperm parameters and testosterone production in rat.Materials and Methods: In this experimental study, forty adult male Wistar rats (220± 20 g were randomly divided into five groups (n=8 for each group. One groupserved as control and one group served as sham control [distilled water was intraperitoneally(i.p. injected]. ACV was administered intraperitoneally in the drugtreatment groups (4, 16 and 48 mg/kg/day for 15 days. Eighteen days after the lastinjection, rats were sacrificed by CO2 inhalation. After that, cauda epididymideswere removed surgically. At the end, sperm concentrations in the cauda epididymis,sperm motility, morphology, viability, chromatin quality and DNA integrity wereanalyzed. Serum testosterone concentrations were determined.Results: The results showed that ACV did not affect sperm count, but decreased spermmotility and sperm viability at 16 and 48 mg/kg dose-levels. Sperm abnormalities increasedat 48 mg/kg dose-level of ACV. Further, ACV significantly increases DNA damageat 16 and 48 mg/kg dose-levels and chromatin abnormality at all doses. Besides, asignificant decrease in serum testosterone concentrations was observed at 16 and 48 mg/kg doses.Conclusion: The present results highly support the idea that ACV induces testicular toxicityby adverse effects on the sperm parameters and serum level of testosterone in malerats.

  10. Estimation of rumen microbial protein production from urinary purine derivatives in zebu cattle and water buffalo

    International Nuclear Information System (INIS)

    Liang, J.B.; Pimpa, O.; Abdullah, N.; Jelan, Z.A.; Nolan, J.V.

    1999-01-01

    Two experiments were conducted in order to develop equations for predicting rumen microbial protein production for indigenous Kedah-Kelantan (KK) cattle and swamp buffaloes in Malaysia, using urinary purine derivatives (PD) excretion rates. Endogenous PD excretion rates determined by a fasting procedure for KK cattle and swamp buffalo were 275 and 370 μmol/kg W 0.75 /day, respectively. Urinary PD excretion rate per kg digestible organic matter intake (DOMI) for KK cattle was higher than that for swamp buffalo, reconfirming the earlier findings. Glomerular filtration rate, allantoin and uric acid tubular load and PD re-absorption rate for swamp buffalo were generally higher than those for KK cattle. However, due to the large variations among animals within species, these parameters were not significantly different between species. Nevertheless, the higher PD reabsorption in swamp buffalo provides support for the earlier postulation that the lower urinary PD excretion rate of swamp buffalo was due to their higher recycling of plasma PD as compared to KK cattle. Labelled 8- 14 C uric acid was used to estimate the ratio of renal to non-renal PD excretion. The recovery rates of the radioactive tracer via the renal route for both species were much lower than values reported previously for unlabelled PD for European cattle. (author)

  11. Purine derivatives/creatinine ratio as an index of microbial protein synthesis in lactating Holstein cows

    International Nuclear Information System (INIS)

    Orellana, R.; Pulido, P.; Briones, M.; Sarabia, A.

    2004-01-01

    Three experiments were conducted to study creatinine excretion in milking cows, and its relationship to food intake and purine derivatives (PD) excretion as an index of microbial N synthesized in the rumen. In the first experiment, differences in creatinine determination method were studied: creatinine excretion was 26.8 ± 1.2 and 27.4 ± 2.2 mg/kg live weight, or 1,175.39 ± 74.69 and 1,199.9 ± 103.9 mmol/kgW 0.75 respectively for HPLC and colorimetry analysis. In the second experiment, the effect of concentrate supplement on the PDC index was studied. The inclusion of different levels of concentrate (0, 16, 33 and 50%) increased the PDC index significantly. The PDC index (Y) also showed a significant relationship with DOMI (X, kg/d): Y 16.85 X + 6.23; R 2 =0.84. Total PD excretion was calculated assuming constant daily excretion of creatinine (1.199 mmol/kgW 0.75 ). In the third experiment the effect of different roughage on the PDC index was studied. The substitution of a 23% of rye grass (Lolium sp.) silage by alkali treated wheat straw did not modify DOMI and the PDC index although among groups there was a significant decrease in milk production (1.5 L/cow/d) and in growth rate (-380 g/cow/d). (author)

  12. Radiochromatographic determination of activity of adenosine deaminase and purine nucleoside phosphorylase in blood cells

    International Nuclear Information System (INIS)

    Pechan, I.; Rendekova, V.; Pechanova, E.; Krizko, J.

    1982-01-01

    Expeditious and sensitive methods are described for determining the activities of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) in human lymphocytes and erythrocytes. ADA and PNP activity is determined on the basis of the reaction of (U- 14 C)adenosine or (8- 14 C)inosine with the lysate of human blood cells. Reaction products are separated using paper chromatography. Following the measurement of the radioactivity of spots of adenosine, inosine and hypoxanthine, a calculation is made of ADA and PNP activity from the results of the said measurements. On a sample of 52 clinically healthy people average ADA and PNP activity in isolated lymphocytes was found to be (51.6+-18.8) and (185.6+-94.7) pcat/10 6 cells and in erythrocytes (9.8+-2.98) and (17.1+-3.19) pcat/mg of proteins, respectively. The advantage of the method is the small amount of sample needed (1 to 2 ml) which allows its application in pediatrics. (Ha)

  13. Synthesis, Characterization, and Thermal and Antimicrobial Activities of Some Novel Organotin(IV: Purine Base Complexes

    Directory of Open Access Journals (Sweden)

    Reena Jain

    2013-01-01

    Full Text Available A new series of organotin(IV complexes with purine bases theophylline (HL1 and theobromine (L2 of the types R3Sn(L1, R2Sn(L1Cl, R3Sn(L2Cl, and R2Sn(L2Cl2 (R = C6H5CH2–; p-ClC6H4CH2– have been synthesized in anhydrous THF. The complexes were characterized by elemental analysis, conductance measurements, molecular weight determinations, UV-vis, IR, 1H, 13C NMR, and mass spectral studies. Various kinetic and thermodynamic parameters of these complexes have also been determined using TG/DTA technique. The thermal decomposition techniques indicate the formation of SnO2 as a residue. The results show that the ligands act as bidentate, forming a five-member chelate ring. All the complexes are 1 : 1 metal-ligand complexes. In order to assess their antimicrobial activity, the ligands and their corresponding complexes have also been tested in vitro against bacteria (E. coli, S. aureus, and P. pyocyanea and fungi (Rhizopus oryzae and Aspergillus flavus. All the complexes exhibit remarkable activity, and the results provide evidence that the studied complexes might indeed be a potential source of antimicrobial agents.

  14. Enzymatic synthesis of RNAs capped with nucleotide analogues reveals the molecular basis for substrate selectivity of RNA capping enzyme: impacts on RNA metabolism.

    Directory of Open Access Journals (Sweden)

    Moheshwarnath Issur

    Full Text Available RNA cap binding proteins have evolved to specifically bind to the N7-methyl guanosine cap structure found at the 5' ends of eukaryotic mRNAs. The specificity of RNA capping enzymes towards GTP for the synthesis of this structure is therefore crucial for mRNA metabolism. The fact that ribavirin triphosphate was described as a substrate of a viral RNA capping enzyme, raised the possibility that RNAs capped with nucleotide analogues could be generated in cellulo. Owing to the fact that this prospect potentially has wide pharmacological implications, we decided to investigate whether the active site of the model Paramecium bursaria Chlorella virus-1 RNA capping enzyme was flexible enough to accommodate various purine analogues. Using this approach, we identified several key structural determinants at each step of the RNA capping reaction and generated RNAs harboring various different cap analogues. Moreover, we monitored the binding affinity of these novel capped RNAs to the eIF4E protein and evaluated their translational properties in cellulo. Overall, this study establishes a molecular rationale for the specific selection of GTP over other NTPs by RNA capping enzyme It also demonstrates that RNAs can be enzymatically capped with certain purine nucleotide analogs, and it also describes the impacts of modified RNA caps on specific steps involved in mRNA metabolism. For instance, our results indicate that the N7-methyl group of the classical N7-methyl guanosine cap is not always indispensable for binding to eIF4E and subsequently for translation when compensatory modifications are present on the capped residue. Overall, these findings have important implications for our understanding of the molecular determinants involved in both RNA capping and RNA metabolism.

  15. Assay of cyclic nucleotide phosphodiesterase using radiolabeled and fluorescent substrates

    International Nuclear Information System (INIS)

    Kincaid, R.L.; Manganiello, V.C.

    1988-01-01

    There are four major classes of phosphodiesterase with different specificities for cAMP and cGMP and different allosteric regulators. Type I phosphodiesterase is activated by calmodulin plus Ca/sup 2+/ and has a higher affinity for cGMP than cAMP. Type II phosphodiesterase likewise has a higher affinity for cGMP than cAMP, but the activity toward one substrate is markedly stimulated by low (micromolar) concentrations of the other nucleotide. Type III phosphodiesterase has a higher affinity for cAMP than cGMP; its activity is increased in responsive cells by certain hormones, e.g., insulin, isoproterenol. Type IV phosphodiesterase is the cGMP-specific enzyme, which also has an allosteric binding site for cGMP. An example of this class of enzyme is the one from retinal rod outer segments, which is activated by light via rhodopsin and the guanine nucleotide-binding protein transducin. There appears to be little structural relatedness among these enzymes based on immunologic analysis, consistent with the possibility that divergent forms evolved from an ancestral enzyme. Determination of the amount of a specific form of phosphodiesterase in crude material is often difficult. Modification of assay conditions by judicious choice of substrate and/or inhibitor concentrations may selectively favor (or reduce) the activity of a particular form; in many instances, however, some fractionation of enzymes may be necessary. This is discussed more fully in the final section of this chapter

  16. The International Nucleotide Sequence Database Collaboration.

    Science.gov (United States)

    Cochrane, Guy; Karsch-Mizrachi, Ilene; Nakamura, Yasukazu

    2011-01-01

    Under the International Nucleotide Sequence Database Collaboration (INSDC; http://www.insdc.org), globally comprehensive public domain nucleotide sequence is captured, preserved and presented. The partners of this long-standing collaboration work closely together to provide data formats and conventions that enable consistent data submission to their databases and support regular data exchange around the globe. Clearly defined policy and governance in relation to free access to data and relationships with journal publishers have positioned INSDC databases as a key provider of the scientific record and a core foundation for the global bioinformatics data infrastructure. While growth in sequence data volumes comes no longer as a surprise to INSDC partners, the uptake of next-generation sequencing technology by mainstream science that we have witnessed in recent years brings a step-change to growth, necessarily making a clear mark on INSDC strategy. In this article, we introduce the INSDC, outline data growth patterns and comment on the challenges of increased growth.

  17. Nucleotide Manipulatives to Illustrate the Central Dogma

    OpenAIRE

    Sonja B. Yung; Todd P. Primm

    2015-01-01

    The central dogma is a core concept that is critical for introductory biology and microbiology students to master. However, students often struggle to conceptualize the processes involved, and fail to move beyond simply memorizing the basic facts. To encourage critical thinking, we have designed a set of magnetic nucleotide manipulatives that allow students to model DNA structure, along with the processes of replication, transcription, and translation.

  18. Nucleotide Manipulatives to Illustrate the Central Dogma

    Directory of Open Access Journals (Sweden)

    Sonja B. Yung

    2015-08-01

    Full Text Available The central dogma is a core concept that is critical for introductory biology and microbiology students to master. However, students often struggle to conceptualize the processes involved, and fail to move beyond simply memorizing the basic facts. To encourage critical thinking, we have designed a set of magnetic nucleotide manipulatives that allow students to model DNA structure, along with the processes of replication, transcription, and translation.

  19. Histone displacement during nucleotide excision repair

    DEFF Research Database (Denmark)

    Dinant, C.; Bartek, J.; Bekker-Jensen, S.

    2012-01-01

    Nucleotide excision repair (NER) is an important DNA repair mechanism required for cellular resistance against UV light and toxic chemicals such as those found in tobacco smoke. In living cells, NER efficiently detects and removes DNA lesions within the large nuclear macromolecular complex called...... of histone variants and histone displacement (including nucleosome sliding). Here we review current knowledge, and speculate about current unknowns, regarding those chromatin remodeling activities that physically displace histones before, during and after NER....

  20. Pyrrolidine nucleotide analogs with a tunable conformation

    Czech Academy of Sciences Publication Activity Database

    Poštová Slavětínská, Lenka; Rejman, Dominik; Pohl, Radek

    2014-01-01

    Roč. 10, Aug 22 (2014), s. 1967-1980 ISSN 1860-5397 R&D Projects: GA ČR GA13-24880S Institutional support: RVO:61388963 Keywords : conformation * NMR * nucleic acids * nucleotide analog * phosphonic acid * pseudorotation * pyrrolidine Subject RIV: CC - Organic Chemistry Impact factor: 2.762, year: 2014 http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-10-205

  1. A fluorimetric readout reporting the kinetics of nucleotide-induced human ribonucleotide reductase oligomerization.

    Science.gov (United States)

    Fu, Yuan; Lin, Hongyu; Wisitpitthaya, Somsinee; Blessing, William A; Aye, Yimon

    2014-11-24

    Human ribonucleotide reductase (hRNR) is a target of nucleotide chemotherapeutics in clinical use. The nucleotide-induced oligomeric regulation of hRNR subunit α is increasingly being recognized as an innate and drug-relevant mechanism for enzyme activity modulation. In the presence of negative feedback inhibitor dATP and leukemia drug clofarabine nucleotides, hRNR-α assembles into catalytically inert hexameric complexes, whereas nucleotide effectors that govern substrate specificity typically trigger α-dimerization. Currently, both knowledge of and tools to interrogate the oligomeric assembly pathway of RNR in any species in real time are lacking. We therefore developed a fluorimetric assay that reliably reports on oligomeric state changes of α with high sensitivity. The oligomerization-directed fluorescence quenching of hRNR-α, covalently labeled with two fluorophores, allows for direct readout of hRNR dimeric and hexameric states. We applied the newly developed platform to reveal the timescales of α self-assembly, driven by the feedback regulator dATP. This information is currently unavailable, despite the pharmaceutical relevance of hRNR oligomeric regulation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Vacuum ultraviolet photoionization of carbohydrates and nucleotides

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Joong-Won, E-mail: jshin@govst.edu [Division of Science, Governors State University, University Park, Illinois 60484-0975 (United States); Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872 (United States); Bernstein, Elliot R., E-mail: erb@lamar.colostate.edu [Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872 (United States)

    2014-01-28

    Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5{sup ′}-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C–C and C–O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results.

  3. Vacuum ultraviolet photoionization of carbohydrates and nucleotides

    International Nuclear Information System (INIS)

    Shin, Joong-Won; Bernstein, Elliot R.

    2014-01-01

    Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5 ′ -monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C–C and C–O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results

  4. Identification of cyclic nucleotide gated channels using regular expressions

    KAUST Repository

    Zelman, Alice K.; Dawe, Adam Sean; Berkowitz, Gerald A.

    2013-01-01

    Cyclic nucleotide-gated channels (CNGCs) are nonselective cation channels found in plants, animals, and some bacteria. They have a six-transmembrane/one- pore structure, a cytosolic cyclic nucleotide-binding domain, and a cytosolic calmodulin

  5. Computational learning on specificity-determining residue-nucleotide interactions

    KAUST Repository

    Wong, Ka-Chun; Li, Yue; Peng, Chengbin; Moses, Alan M.; Zhang, Zhaolei

    2015-01-01

    The protein–DNA interactions between transcription factors and transcription factor binding sites are essential activities in gene regulation. To decipher the binding codes, it is a long-standing challenge to understand the binding mechanism across different transcription factor DNA binding families. Past computational learning studies usually focus on learning and predicting the DNA binding residues on protein side. Taking into account both sides (protein and DNA), we propose and describe a computational study for learning the specificity-determining residue-nucleotide interactions of different known DNA-binding domain families. The proposed learning models are compared to state-of-the-art models comprehensively, demonstrating its competitive learning performance. In addition, we describe and propose two applications which demonstrate how the learnt models can provide meaningful insights into protein–DNA interactions across different DNA binding families.

  6. Computational learning on specificity-determining residue-nucleotide interactions

    KAUST Repository

    Wong, Ka-Chun

    2015-11-02

    The protein–DNA interactions between transcription factors and transcription factor binding sites are essential activities in gene regulation. To decipher the binding codes, it is a long-standing challenge to understand the binding mechanism across different transcription factor DNA binding families. Past computational learning studies usually focus on learning and predicting the DNA binding residues on protein side. Taking into account both sides (protein and DNA), we propose and describe a computational study for learning the specificity-determining residue-nucleotide interactions of different known DNA-binding domain families. The proposed learning models are compared to state-of-the-art models comprehensively, demonstrating its competitive learning performance. In addition, we describe and propose two applications which demonstrate how the learnt models can provide meaningful insights into protein–DNA interactions across different DNA binding families.

  7. Guanylic nucleotide starvation affects Saccharomyces cerevisiae mother-daughter separation and may be a signal for entry into quiescence

    Directory of Open Access Journals (Sweden)

    Sagot Isabelle

    2005-05-01

    Full Text Available Abstract Background Guanylic nucleotides are both macromolecules constituents and crucial regulators for a variety of cellular processes. Therefore, their intracellular concentration must be strictly controlled. Consistently both yeast and mammalian cells tightly correlate the transcription of genes encoding enzymes critical for guanylic nucleotides biosynthesis with the proliferation state of the cell population. Results To gain insight into the molecular relationships connecting intracellular guanylic nucleotide levels and cellular proliferation, we have studied the consequences of guanylic nucleotide limitation on Saccharomyces cerevisiae cell cycle progression. We first utilized mycophenolic acid, an immunosuppressive drug that specifically inhibits inosine monophosphate dehydrogenase, the enzyme catalyzing the first committed step in de novo GMP biosynthesis. To approach this system physiologically, we next developed yeast mutants for which the intracellular guanylic nucleotide pools can be modulated through changes of growth conditions. In both the pharmacological and genetic approaches, we found that guanylic nucleotide limitation generated a mother-daughter separation defect, characterized by cells with two unseparated daughters. We then showed that this separation defect resulted from cell wall perturbations but not from impaired cytokinesis. Importantly, cells with similar separation defects were found in a wild type untreated yeast population entering quiescence upon nutrient limitation. Conclusion Our results demonstrate that guanylic nucleotide limitation slows budding yeast cell cycle progression, with a severe pause in telophase. At the cellular level, guanylic nucleotide limitation causes the emergence of cells with two unseparated daughters. By fluorescence and electron microscopy, we demonstrate that this phenotype arises from defects in cell wall partition between mother and daughter cells. Because cells with two unseparated

  8. The evolutionary fate of the genes encoding the purine catabolic enzymes in hominoids, birds, and reptiles.

    Science.gov (United States)

    Keebaugh, Alaine C; Thomas, James W

    2010-06-01

    Gene loss has been proposed to play a major role in adaptive evolution, and recent studies are beginning to reveal its importance in human evolution. However, the potential consequence of a single gene-loss event upon the fates of functionally interrelated genes is poorly understood. Here, we use the purine metabolic pathway as a model system in which to explore this important question. The loss of urate oxidase (UOX) activity, a necessary step in this pathway, has occurred independently in the hominoid and bird/reptile lineages. Because the loss of UOX would have removed the functional constraint upon downstream genes in this pathway, these downstream genes are generally assumed to have subsequently deteriorated. In this study, we used a comparative genomics approach to empirically determine the fate of UOX itself and the downstream genes in five hominoids, two birds, and a reptile. Although we found that the loss of UOX likely triggered the genetic deterioration of the immediate downstream genes in the hominoids, surprisingly in the birds and reptiles, the UOX locus itself and some of the downstream genes were present in the genome and predicted to encode proteins. To account for the variable pattern of gene retention and loss after the inactivation of UOX, we hypothesize that although gene loss is a common fate for genes that have been rendered obsolete due to the upstream loss of an enzyme a metabolic pathway, it is also possible that same lack of constraint will foster the evolution of new functions or allow the optimization of preexisting alternative functions in the downstream genes, thereby resulting in gene retention. Thus, adaptive single-gene losses have the potential to influence the long-term evolutionary fate of functionally interrelated genes.

  9. Autoimmune dysregulation and purine metabolism in adenosine deaminase (ADA-deficiency

    Directory of Open Access Journals (Sweden)

    Aisha Vanessa Sauer

    2012-08-01

    Full Text Available Genetic defects in the adenosine deaminase (ADA gene are among the most common causes for severe combined immunodeficiency (SCID. ADA-SCID patients suffer from lymphopenia, severely impaired cellular and humoral immunity, failure to thrive and recurrent infections. Currently available therapeutic options for this otherwise fatal disorder include bone marrow transplantation (BMT, enzyme replacement therapy with bovine ADA (PEG-ADA or hematopoietic stem cell gene therapy (HSC-GT. Although varying degrees of immune reconstitution can be achieved by these treatments, breakdown of tolerance is a major concern in ADA-SCID. Immune dysregulation such as autoimmune hypothyroidism, diabetes mellitus, hemolytic anemia, and immune thrombocytopenia are frequently observed in milder forms of the disease. However, several reports document similar complications also in patients on long-term PEG-ADA and after BMT or GT treatment.A skewed repertoire and decreased immune functions have been implicated in autoimmunity observed in certain B-cell and/or T-cell immunodeficiencies, but it remains unclear to what extent specific mechanisms of tolerance are affected in ADA deficiency. Herein we provide an overview about ADA-SCID and the autoimmune manifestations reported in these patients before and after treatment. We also assess the value of the ADA-deficient mouse model as a useful tool to study both immune and metabolic disease mechanisms. With focus on regulatory T and B cells we discuss the lymphocyte subpopulations particularly prone to contribute to the loss of self-tolerance and onset of autoimmunity in ADA deficiency. Moreover we address which aspects of immune dysregulation are specifically related to alterations in purine metabolism caused by the lack of ADA and the subsequent accumulation of metabolites with immunomodulatory properties.

  10. Four Generations of Transition State Analogues for Human Purine Nucleoside Phosphorylase

    Energy Technology Data Exchange (ETDEWEB)

    Ho, M.; Shi, W; Rinaldo-Mathis, A; Tyler, P; Evans, G; Almo, S; Schramm, V

    2010-01-01

    Inhibition of human purine nucleoside phosphorylase (PNP) stops growth of activated T-cells and the formation of 6-oxypurine bases, making it a target for leukemia, autoimmune disorders, and gout. Four generations of ribocation transition-state mimics bound to PNP are structurally characterized. Immucillin-H (K*{sub i} = 58 pM, first-generation) contains an iminoribitol cation with four asymmetric carbons. DADMe-Immucillin-H (K*{sub i} = 9 pM, second-generation), uses a methylene-bridged dihydroxypyrrolidine cation with two asymmetric centers. DATMe-Immucillin-H (K*{sub i} = 9 pM, third-generation) contains an open-chain amino alcohol cation with two asymmetric carbons. SerMe-ImmH (K*{sub i} = 5 pM, fourth-generation) uses achiral dihydroxyaminoalcohol seramide as the ribocation mimic. Crystal structures of PNPs establish features of tight binding to be; (1) ion-pair formation between bound phosphate (or its mimic) and inhibitor cation, (2) leaving-group interactions to N1, O6, and N7 of 9-deazahypoxanthine, (3) interaction between phosphate and inhibitor hydroxyl groups, and (4) His257 interacting with the 5{prime}-hydroxyl group. The first generation analogue is an imperfect fit to the catalytic site with a long ion pair distance between the iminoribitol and bound phosphate and weaker interactions to the leaving group. Increasing the ribocation to leaving-group distance in the second- to fourth-generation analogues provides powerful binding interactions and a facile synthetic route to powerful inhibitors. Despite chemical diversity in the four generations of transition-state analogues, the catalytic site geometry is almost the same for all analogues. Multiple solutions in transition-state analogue design are available to convert the energy of catalytic rate enhancement to binding energy in human PNP.

  11. Nucleotide Interdependency in Transcription Factor Binding Sites in the Drosophila Genome.

    Science.gov (United States)

    Dresch, Jacqueline M; Zellers, Rowan G; Bork, Daniel K; Drewell, Robert A

    2016-01-01

    A long-standing objective in modern biology is to characterize the molecular components that drive the development of an organism. At the heart of eukaryotic development lies gene regulation. On the molecular level, much of the research in this field has focused on the binding of transcription factors (TFs) to regulatory regions in the genome known as cis-regulatory modules (CRMs). However, relatively little is known about the sequence-specific binding preferences of many TFs, especially with respect to the possible interdependencies between the nucleotides that make up binding sites. A particular limitation of many existing algorithms that aim to predict binding site sequences is that they do not allow for dependencies between nonadjacent nucleotides. In this study, we use a recently developed computational algorithm, MARZ, to compare binding site sequences using 32 distinct models in a systematic and unbiased approach to explore nucleotide dependencies within binding sites for 15 distinct TFs known to be critical to Drosophila development. Our results indicate that many of these proteins have varying levels of nucleotide interdependencies within their DNA recognition sequences, and that, in some cases, models that account for these dependencies greatly outperform traditional models that are used to predict binding sites. We also directly compare the ability of different models to identify the known KRUPPEL TF binding sites in CRMs and demonstrate that a more complex model that accounts for nucleotide interdependencies performs better when compared with simple models. This ability to identify TFs with critical nucleotide interdependencies in their binding sites will lead to a deeper understanding of how these molecular characteristics contribute to the architecture of CRMs and the precise regulation of transcription during organismal development.

  12. GDP-bound and nucleotide-free intermediates of the guanine nucleotide exchange in the Rab5·Vps9 system.

    Science.gov (United States)

    Uejima, Tamami; Ihara, Kentaro; Goh, Tatsuaki; Ito, Emi; Sunada, Mariko; Ueda, Takashi; Nakano, Akihiko; Wakatsuki, Soichi

    2010-11-19

    Many GTPases regulate intracellular transport and signaling in eukaryotes. Guanine nucleotide exchange factors (GEFs) activate GTPases by catalyzing the exchange of their GDP for GTP. Here we present crystallographic and biochemical studies of a GEF reaction with four crystal structures of Arabidopsis thaliana ARA7, a plant homolog of Rab5 GTPase, in complex with its GEF, VPS9a, in the nucleotide-free and GDP-bound forms, as well as a complex with aminophosphonic acid-guanylate ester and ARA7·VPS9a(D185N) with GDP. Upon complex formation with ARA7, VPS9 wedges into the interswitch region of ARA7, inhibiting the coordination of Mg(2+) and decreasing the stability of GDP binding. The aspartate finger of VPS9a recognizes GDP β-phosphate directly and pulls the P-loop lysine of ARA7 away from GDP β-phosphate toward switch II to further destabilize GDP for its release during the transition from the GDP-bound to nucleotide-free intermediates in the nucleotide exchange reaction.

  13. Poly(alizarin red)/Graphene modified glassy carbon electrode for simultaneous determination of purine and pyrimidine

    Energy Technology Data Exchange (ETDEWEB)

    Ba Xi; Luo Liqiang [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Ding Yaping, E-mail: wdingyp@sina.com [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Zhang Zhen [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Chu Yuliang [Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444 (China); Wang Bijun; Ouyang Xiaoqian [Department of Chemistry, Shanghai University, Shanghai 200444 (China)

    2012-11-08

    Graphical abstract: DPVs of PAR/Graphene/GCE (a) and the bare GCE (c) in 0.1 M PBS containing 50.0 {mu}M G, 50.0 {mu}M A, 100.0 {mu}M T and 100.0 {mu}M C, (b) PAR/Graphene/GCE in 0.1 M PBS. Highlights: Black-Right-Pointing-Pointer The sensor exhibited well-separated peaks and low detection limit. Black-Right-Pointing-Pointer The sensor possesses high sensitivity and wide linear range. Black-Right-Pointing-Pointer The sensor was used for simultaneous detection of G, A, T and C successfully. Black-Right-Pointing-Pointer The sensor was applied in a fish sperm DNA sample with satisfactory results. Black-Right-Pointing-Pointer The proposed sensor has good stability and reproducibility. - Abstract: In this work, a poly(alizarin red)/Graphene composite film modified glassy carbon electrode (PAR/Graphene/GCE) was prepared for simultaneous determination of four DNA bases (guanine, adenine, thymine and cytosine) without any pretreatment. The morphology and interface property of PAR/Graphene films were examined by scanning electron microscopy and electrochemical impedance spectroscopy. The PAR/Graphene/GCE exhibited excellent electrocatalytic activity toward purine (guanine and adenine) and pyrimidine (thymine and cytosine) in 0.1 M phosphate buffer solution (pH 7.4). Under optimum conditions, differential pulse voltammetry was used to detect the oxidation of purine and pyrimidine. The results showed that PAR/Graphene/GCE exhibited well-separated peaks, low detection limit, high sensitivity and wide linear range for simultaneous detection of purine and pyrimidine. The proposed sensor also has good stability and reproducibility. Furthermore, the modified electrode was applied for the detection of DNA bases in a fish sperm DNA sample with satisfactory results.

  14. Poly(alizarin red)/Graphene modified glassy carbon electrode for simultaneous determination of purine and pyrimidine

    International Nuclear Information System (INIS)

    Ba Xi; Luo Liqiang; Ding Yaping; Zhang Zhen; Chu Yuliang; Wang Bijun; Ouyang Xiaoqian

    2012-01-01

    Graphical abstract: DPVs of PAR/Graphene/GCE (a) and the bare GCE (c) in 0.1 M PBS containing 50.0 μM G, 50.0 μM A, 100.0 μM T and 100.0 μM C, (b) PAR/Graphene/GCE in 0.1 M PBS. Highlights: ► The sensor exhibited well-separated peaks and low detection limit. ► The sensor possesses high sensitivity and wide linear range. ► The sensor was used for simultaneous detection of G, A, T and C successfully. ► The sensor was applied in a fish sperm DNA sample with satisfactory results. ► The proposed sensor has good stability and reproducibility. - Abstract: In this work, a poly(alizarin red)/Graphene composite film modified glassy carbon electrode (PAR/Graphene/GCE) was prepared for simultaneous determination of four DNA bases (guanine, adenine, thymine and cytosine) without any pretreatment. The morphology and interface property of PAR/Graphene films were examined by scanning electron microscopy and electrochemical impedance spectroscopy. The PAR/Graphene/GCE exhibited excellent electrocatalytic activity toward purine (guanine and adenine) and pyrimidine (thymine and cytosine) in 0.1 M phosphate buffer solution (pH 7.4). Under optimum conditions, differential pulse voltammetry was used to detect the oxidation of purine and pyrimidine. The results showed that PAR/Graphene/GCE exhibited well-separated peaks, low detection limit, high sensitivity and wide linear range for simultaneous detection of purine and pyrimidine. The proposed sensor also has good stability and reproducibility. Furthermore, the modified electrode was applied for the detection of DNA bases in a fish sperm DNA sample with satisfactory results.

  15. [Separation of purines, pyrimidines, pterins and flavonoids on magnolol-bonded silica gel stationary phase by high performance liquid chromatography].

    Science.gov (United States)

    Chen, Hong; Li, Laishen; Zhang, Yang; Zhou, Rendan

    2012-10-01

    A new magnolol-bonded silica gel stationary phase (MSP) was used to separate the basic drugs including four purines, eight pyrimidines, four pterins and five flavonoids as polar representative samples by high performance liquid chromatography (HPLC). To clarify the separation mechanism, a commercial ODS column was also tested under the same chromatographic conditions. The high selectivities and fast baseline separations of the above drugs were achieved by using simple mobile phases on MSP. Although there is no end-caped treatment, the peak shapes of basic drugs containing nitrogen such as purines, pyrimidines and pterins were rather symmetrical on MSP, which indicated the the magnolol as ligand with multi-sites could shield the side effect of residual silanol groups on the surface of silica gel. Although somewhat different in the separation resolution, it was found that the elution orders of some drugs were generally similar on both MSP and ODS. The hydrophobic interaction should play a significant role in the separations of the above basic drugs, which was attributed to their reversed-phase property in the nature. However, MSP could provide the additional sites for many polar solutes, which was a rational explanation for the high selectivity of MSP. For example, in the separation of purines, pyrimidines and pterins on MSP, hydrogen-bonding and dipole-dipole interactions played leading roles besides hydrophobic interaction. Some solute molecules (such as mercaptopurine, vitexicarpin) and MSP can form the strong pi-pi stacking in the separation process. All enhanced the retention and improved the separation selectivity of MSP, which facilitated the separation of the basic drugs.

  16. Identification of genes containing expanded purine repeats in the human genome and their apparent protective role against cancer.

    Science.gov (United States)

    Singh, Himanshu Narayan; Rajeswari, Moganty R

    2016-01-01

    Purine repeat sequences present in a gene are unique as they have high propensity to form unusual DNA-triple helix structures. Friedreich's ataxia is the only human disease that is well known to be associated with DNA-triplexes formed by purine repeats. The purpose of this study was to recognize the expanded purine repeats (EPRs) in human genome and find their correlation with cancer pathogenesis. We developed "PuRepeatFinder.pl" algorithm to identify non-overlapping EPRs without pyrimidine interruptions in the human genome and customized for searching repeat lengths, n ≥ 200. A total of 1158 EPRs were identified in the genome which followed Wakeby distribution. Two hundred and ninety-six EPRs were found in geneic regions of 282 genes (EPR-genes). Gene clustering of EPR-genes was done based on their cellular function and a large number of EPR-genes were found to be enzymes/enzyme modulators. Meta-analysis of 282 EPR-genes identified only 63 EPR-genes in association with cancer, mostly in breast, lung, and blood cancers. Protein-protein interaction network analysis of all 282 EPR-genes identified proteins including those in cadherins and VEGF. The two observations, that EPRs can induce mutations under malignant conditions and that identification of some EPR-gene products in vital cell signaling-mediated pathways, together suggest the crucial role of EPRs in carcinogenesis. The new link between EPR-genes and their functionally interacting proteins throws a new dimension in the present understanding of cancer pathogenesis and can help in planning therapeutic strategies. Validation of present results using techniques like NGS is required to establish the role of the EPR genes in cancer pathology.

  17. Interpretation of substituent effects on 13C and 15N NMR chemical shifts in 6-substituted purines

    Czech Academy of Sciences Publication Activity Database

    Standara, Stanislav; Bouzková, K.; Straka, Michal; Zacharová, Z.; Hocek, Michal; Marek, J.; Marek, R.

    2011-01-01

    Roč. 13, č. 35 (2011), s. 15854-15864 ISSN 1463-9076 R&D Projects: GA ČR GA203/09/2037 Grant - others:CEITEC(XE) CZ.1.05/1.1.00/02.0068; 7th European Community Framework (XE) 230955; GA MŠk(CZ) LC06030 Program:LC Institutional research plan: CEZ:AV0Z40550506 Keywords : purine * nuclear magnetic shielding * localized molecular orbitals * conformational dependence Subject RIV: CC - Organic Chemistry Impact factor: 3.573, year: 2011

  18. Influence of sap's mixture of the plantain and the burdock on energetic and purine exchange of irradiated organism under stress

    International Nuclear Information System (INIS)

    Raisov, T.K.; Agafonova, I.P.; Zhetpisbaev, B.A.

    1996-01-01

    One of immuno correctors under development of common adaptive syndrome is saps's mixture of the plantain and the burdock. Research of influence of saps's mixture of the plantain and the burdock on enzymes activity of energetic and purine exchange under stress was carried out. There were 2 series of experiments with 120 white rats. Results showed that the irradiated animals on the background phyto therapy had high enzymes activity under stress during all of the investigation periods. The preparations from plantain and burdock biomass increase unspecific resistivity of organism and helps of energetic exchange's rise irradiated organs's sells of animals under stress

  19. Purine derivatives excretion function in relation to the fiber/protein ratio in the diet of alpacas (Vicugna pacos)

    OpenAIRE

    Rúa M., Viviana; Olazábal L., Juan; San Martín H., Felipe

    2017-01-01

    The aim of this study was to evaluate the relationship of the neutral detergent fibre/ crude protein on urinary excretion of purine derivatives (PD) in alpacas. The experimental design was a 3x3 Latin Square. Three male Huacaya alpacas, 2.5 years old, confined in individual pens were used. Feed was provided once daily and water ad libitum. Three treatments based on oat hay were used where the ratios of fibre/protein was obtained according to the proportions of stems and leaves. The treatments...

  20. Functional analysis of 14 genes that constitute the purine catabolic pathway in Bacillus subtilis and evidence for a novel regulon controlled by the PucR transcription activator

    DEFF Research Database (Denmark)

    Schultz, Anna Charlotte; Nygaard, P.; Saxild, Hans Henrik

    2001-01-01

    The soil bacterium Bacillus subtilis has developed a highly controlled system for the utilization of a diverse array of low molecular-weight compounds as a nitrogen source when the preferred nitrogen sources, e.g., glutamate plus ammonia, are exhausted. We have identified such a system...... for the utilization of purines as nitrogen source in B. subtilis. Based on growth studies of strains with knockout mutations in genes, complemented with enzyme analysis, we could ascribe functions to 14 genes encoding enzymes or proteins of the purine degradation pathway. A functional xanthine dehydrogenase requires......ABCDE unit was decreased 16-fold, while expression of pucR was decreased 4-fold in the presence of allantoin. We have identified genes of the purine degradation pathway in B. subtilis and showed that their expression is subject to both general nitrogen catabolite control and pathway-specific control....

  1. Ribose Supplementation Alone or with Elevated Creatine Does Not Preserve High Energy Nucleotides or Cardiac Function in the Failing Mouse Heart.

    Directory of Open Access Journals (Sweden)

    Kiterie M E Faller

    Full Text Available Reduced levels of creatine and total adenine nucleotides (sum of ATP, ADP and AMP are hallmarks of chronic heart failure and restoring these pools is predicted to be beneficial by maintaining the diseased heart in a more favourable energy state. Ribose supplementation is thought to support both salvage and re-synthesis of adenine nucleotides by bypassing the rate-limiting step. We therefore tested whether ribose would be beneficial in chronic heart failure in control mice and in mice with elevated myocardial creatine due to overexpression of the creatine transporter (CrT-OE.FOUR GROUPS WERE STUDIED: sham; myocardial infarction (MI; MI+ribose; MI+CrT-OE+ribose. In a pilot study, ribose given in drinking water was bioavailable, resulting in a two-fold increase in myocardial ribose-5-phosphate levels. However, 8 weeks post-surgery, total adenine nucleotide (TAN pool was decreased to a similar amount (8-14% in all infarcted groups irrespective of the treatment received. All infarcted groups also presented with a similar and substantial degree of left ventricular (LV dysfunction (3-fold reduction in ejection fraction and LV hypertrophy (32-47% increased mass. Ejection fraction closely correlated with infarct size independently of treatment (r(2 = 0.63, p<0.0001, but did not correlate with myocardial creatine or TAN levels.Elevating myocardial ribose and creatine levels failed to maintain TAN pool or improve post-infarction LV remodeling and function. This suggests that ribose is not rate-limiting for purine nucleotide biosynthesis in the chronically failing mouse heart and that alternative strategies to preserve TAN pool should be investigated.

  2. Novel, Highly Specific N-Demethylases Enable Bacteria To Live on Caffeine and Related Purine Alkaloids

    Science.gov (United States)

    Summers, Ryan M.; Louie, Tai Man; Yu, Chi-Li; Gakhar, Lokesh; Louie, Kailin C.

    2012-01-01

    The molecular basis for the ability of bacteria to live on caffeine as a sole carbon and nitrogen source is unknown. Pseudomonas putida CBB5, which grows on several purine alkaloids, metabolizes caffeine and related methylxanthines via sequential N-demethylation to xanthine. Metabolism of caffeine by CBB5 was previously attributed to one broad-specificity methylxanthine N-demethylase composed of two subunits, NdmA and NdmB. Here, we report that NdmA and NdmB are actually two independent Rieske nonheme iron monooxygenases with N1- and N3-specific N-demethylation activity, respectively. Activity for both enzymes is dependent on electron transfer from NADH via a redox-center-dense Rieske reductase, NdmD. NdmD itself is a novel protein with one Rieske [2Fe-2S] cluster, one plant-type [2Fe-2S] cluster, and one flavin mononucleotide (FMN) per enzyme. All ndm genes are located in a 13.2-kb genomic DNA fragment which also contained a formaldehyde dehydrogenase. ndmA, ndmB, and ndmD were cloned as His6 fusion genes, expressed in Escherichia coli, and purified using a Ni-NTA column. NdmA-His6 plus His6-NdmD catalyzed N1-demethylation of caffeine, theophylline, paraxanthine, and 1-methylxanthine to theobromine, 3-methylxanthine, 7-methylxanthine, and xanthine, respectively. NdmB-His6 plus His6-NdmD catalyzed N3-demethylation of theobromine, 3-methylxanthine, caffeine, and theophylline to 7-methylxanthine, xanthine, paraxanthine, and 1-methylxanthine, respectively. One formaldehyde was produced from each methyl group removed. Activity of an N7-specific N-demethylase, NdmC, has been confirmed biochemically. This is the first report of bacterial N-demethylase genes that enable bacteria to live on caffeine. These genes represent a new class of Rieske oxygenases and have the potential to produce biofuels, animal feed, and pharmaceuticals from coffee and tea waste. PMID:22328667

  3. Measuring microbial protein supply from purine excretion in Yerli Kara cattle in Turkey

    International Nuclear Information System (INIS)

    Cetinkaya, N.; Gucus, A.I.; Ozcan, H.; Uluturk, S.; Yaman, S.

    1999-01-01

    The urinary excretion of purine derivatives (PD) was measured in four Yerli Kara (Bos indicus) bulls in two experiments, a fasting experiment lasting for 7 days and the other, where animals were given a diet containing 30% wheat straw and 70% compounded feed at four levels of intake (40, 60, 80 and 95% of voluntary feed intake). In the second experiment, which was carried out according to a 4 x 4 Latin Square design, four animals receiving 60 and 95% levels of intake were also given a single injection of 8- 14 C-uric acid via a jugular catheter. In addition to the above two experiments, the activity of xanthine oxidase and uricase in plasma, liver and intestinal mucosa obtained from Yerli Kara cattle was also determined. In the first experiment, fasting PD excretion averaged 0.691 (± 0.053) mmol/kg W 0.75 /d. Glomerular filtration rate (GFR), tubular load and net re-absorption of allantoin between pre-fasting and fasting were statistically significant (P 14 C-uric acid as total PD was 72.5 and 89.9% for 60 and 95% feeding levels, respectively. The average recovery was 81%. Plasma kinetics measured by 8- 14 C-uric acid indicated that the total compartment pool size was 214.0 (± 43.8) and 250.3 L (± 29.5) for 60 and 95% feeding levels, respectively. GFR, tubular load and net re-absorption of uric acid and allantoin were not affected by feed intake. The allantoin:PD molar ratios changed between 0.78 to 0.93 for the four levels feed intake. There were significant correlations between PD excretion (mmol/d), and DDMI (kg/d) and DOMI (kg/d) (r = 0.99, P 0.75 DDMI, 19.8 mmol/kg DDMI and 22.7 mmol/kg DOMI. Xanthine oxidase and uricase activities were: 1.34 (± 0.72) and 0.44 (± 0.05), and 0.13 (± 0.03) and 0.08 (± 0.03) unit/g fresh tissue in liver and intestinal mucosa, respectively. In plasma xanthine oxidase activity was 5.0 (± 1.2) unit/L while uricase activity was absent. (author)

  4. Development of a neutral network model to predict the excretion of purine derivatives in the urine of cows

    International Nuclear Information System (INIS)

    Volpe, V.; Stefanon, B.; Moscardini, S.; Susmel, P.; Gruber, L.

    1999-01-01

    A Neural Network Model to predict the urinary excretion of purine derivative nitrogen (UPDN) in cows is presented. The input variables of the model are dry matter intake (DMINT), NDF intake (NDFINT), total soluble nitrogen (SP), total soluble non-protein dry matter (SNPDM), total degradable nitrogen (DCP), total degradable non-protein dry matter (DNPDM), hourly available CP in the rumen (HACP), hourly available non-protein dry matter (HANPDM), three different gross indexes of synchronization, namely SYNCA (SP/SNPDM), SYNCB (DCP/DNPDM) and SYNCK (HACP/HANPDM) and two variables describing some metabolic aspects of purine derivative excretion such as live weight of the cow (LW) and milk yield (MILKY). The Model developed uses the Multi Layer Perceptron (MLP) utility, with 13 nodes in the input layer, 8 nodes in the hidden layer and 1 node in the output layer. The Model performances have been tested over 24 observations not previously used to train the model. When compared to a linear regression approach, the Neural Network model showed better performance but under predicted the daily excretion of UPDN for values around 20 g/day. When evaluated in terms of behaviour and depicted scenario the model responded to changes of live weight (LW) and milk yield (MILKY) and to modifications of the pattern of nutrients supplied to rumen microbes. (author)

  5. Comparison of purine derivatives and creatinine in plasma and urine between local cattle and buffaloes in Vietnam

    International Nuclear Information System (INIS)

    Vo Thi Kim Thanh; Dao Thi Phuong; Tran Thi Thu Hong; Phung Thi Luu; Ngo Mau Dung; Hoang Quoc Hung; Orskov, E.R.

    2004-01-01

    In Experiment I, 4 female swamp buffaloes and 4 local cattle fed with the diet based on young maize and rice straw (80/20), and in experiment II, the same number and types of animals as in Experiment I were fed with the diet based on rice straw and rice bran (70/30). The animals were fed twice a day with the diets at 40, 60, 80, 95% of ad libitum intake. The digestibility of nutrients and N excretion were similar for cattle and buffaloes. The purine derivative:creatinine ratio (PDC) index was significantly affected by the level of feed intake (P < 0.001) in both the species. Large differences in urinary purine derivative (PD) excretion were observed, being much lower in buffaloes than in cattle. The regression analysis showed that urinary PD excretion rate per kg of digestible organic matter intake for cattle was higher than that for buffalo. The PDC index also followed the same pattern. The nitrogen retention increased with the supply of energy, both in cattle and buffaloes, indicating that the protein supply was similar. There was no consistent effect of time of day on spot sampling in buffalo and cattle. Buffaloes urinated less frequently than cattle, so sampling time was not really relevant. (author)

  6. A Multitarget Approach toward the Development of 8-Substituted Purines for Photoprotection and Prevention of UV-Related Damage.

    Science.gov (United States)

    Djuidje, Ernestine N; Dissette, Valeria; Bino, Alessia; Benetti, Simonetta; Balzarini, Jan; Liekens, Sandra; Manfredini, Stefano; Vertuani, Silvia; Baldisserotto, Anna

    2017-05-22

    Ultraviolet (UV) light is the most abundant and significant modifiable risk factor for skin cancer and many other skin diseases such as early photo-aging. Across the solar radiation spectrum, UV light is the main cause behind skin problems. In the search for novel photoprotective compounds, a new series of 8-substituted purines were synthesized from commercially available 6-hydroxy-4,5-diaminopyrimidine hemisulfate or 4,5-diaminopyrimidine. All title compounds were investigated for their UV filtering, antioxidant, antifungal, and antiproliferative activities. For the photoprotection assays we used a diffuse transmittance technique to determine the sun protection factor (SPF) in vitro, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP) tests for evaluating the antioxidant activity of the more potent compounds. Among them, 8-(2,5-dihydroxyphenyl)-7H-purin-6-ol (compound 26) proved to be a good radical scavenger and is also endowed with broad-spectrum UVA filtering capabilities, suitable for further development as a protective molecule. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Development of a neutral network model to predict the excretion of purine derivatives in the urine of cows

    Energy Technology Data Exchange (ETDEWEB)

    Volpe, V; Stefanon, B; Moscardini, S; Susmel, P [University of Udine, Department of Animal Production Science, Pagnacco, UD (Italy); Gruber, L [Federal Research Institute for Agriculture in the Alpine Regions, Irdning (Austria)

    1999-06-01

    A Neural Network Model to predict the urinary excretion of purine derivative nitrogen (UPDN) in cows is presented. The input variables of the model are dry matter intake (DMINT), NDF intake (NDFINT), total soluble nitrogen (SP), total soluble non-protein dry matter (SNPDM), total degradable nitrogen (DCP), total degradable non-protein dry matter (DNPDM), hourly available CP in the rumen (HACP), hourly available non-protein dry matter (HANPDM), three different gross indexes of synchronization, namely SYNCA (SP/SNPDM), SYNCB (DCP/DNPDM) and SYNCK (HACP/HANPDM) and two variables describing some metabolic aspects of purine derivative excretion such as live weight of the cow (LW) and milk yield (MILKY). The Model developed uses the Multi Layer Perceptron (MLP) utility, with 13 nodes in the input layer, 8 nodes in the hidden layer and 1 node in the output layer. The Model performances have been tested over 24 observations not previously used to train the model. When compared to a linear regression approach, the Neural Network model showed better performance but under predicted the daily excretion of UPDN for values around 20 g/day. When evaluated in terms of behaviour and depicted scenario the model responded to changes of live weight (LW) and milk yield (MILKY) and to modifications of the pattern of nutrients supplied to rumen microbes. (author) 16 refs, 11 figs, 1 tab

  8. Ni2+-binding RNA motifs with an asymmetric purine-rich internal loop and a G-A base pair.

    Science.gov (United States)

    Hofmann, H P; Limmer, S; Hornung, V; Sprinzl, M

    1997-01-01

    RNA molecules with high affinity for immobilized Ni2+ were isolated from an RNA pool with 50 randomized positions by in vitro selection-amplification. The selected RNAs preferentially bind Ni2+ and Co2+ over other cations from first series transition metals. Conserved structure motifs, comprising about 15 nt, were identified that are likely to represent the Ni2+ binding sites. Two conserved motifs contain an asymmetric purine-rich internal loop and probably a mismatch G-A base pair. The structure of one of these motifs was studied with proton NMR spectroscopy and formation of the G-A pair at the junction of helix and internal loop was demonstrated. Using Ni2+ as a paramagnetic probe, a divalent metal ion binding site near this G-A base pair was identified. Ni2+ ions bound to this motif exert a specific stabilization effect. We propose that small asymmetric purine-rich loops that contain a G-A interaction may represent a divalent metal ion binding site in RNA. PMID:9409620

  9. Trisubstituted purine inhibitors of PDGFRα and their antileukemic activity in the human eosinophilic cell line EOL-1.

    Science.gov (United States)

    Malínková, Veronika; Řezníčková, Eva; Jorda, Radek; Gucký, Tomáš; Kryštof, Vladimír

    2017-12-15

    Inhibition of protein kinases is a validated concept for pharmacological intervention in cancers. Many kinase inhibitors have been approved for clinical use, but their practical application is often limited. Here, we describe a collection of 23 novel 2,6,9-trisubstituted purine derivatives with nanomolar inhibitory activities against PDGFRα, a receptor tyrosine kinase often found constitutively activated in various tumours. The compounds demonstrated strong and selective cytotoxicity in the human eosinophilic leukemia cell line EOL-1, whereas several other cell lines were substantially less sensitive. The cytotoxicity in EOL-1, which is known to express the FIP1L1-PDGFRA fusion gene encoding an oncogenic kinase, correlated significantly with PDGFRα inhibition. EOL-1 cells treated with the compounds also exhibited dose-dependent inhibition of PDGFRα autophosphorylation and suppression of its downstream signaling pathways with concomitant G 1 phase arrest, confirming the proposed mechanism of action. Our results show that substituted purines can be used as platforms for preparing tyrosine kinase inhibitors with specific activity towards eosinophilic leukemia. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Genome-wide screening for genes whose deletions confer sensitivity to mutagenic purine base analogs in yeast

    Directory of Open Access Journals (Sweden)

    Kozmin Stanislav G

    2005-06-01

    Full Text Available Abstract Background N-hydroxylated base analogs, such as 6-hydroxylaminopurine (HAP and 2-amino-6-hydroxylaminopurine (AHA, are strong mutagens in various organisms due to their ambiguous base-pairing properties. The systems protecting cells from HAP and related noncanonical purines in Escherichia coli include specialized deoxyribonucleoside triphosphatase RdgB, DNA repair endonuclease V, and a molybdenum cofactor-dependent system. Fewer HAP-detoxification systems have been identified in yeast Saccharomyces cerevisiae and other eukaryotes. Cellular systems protecting from AHA are unknown. In the present study, we performed a genome-wide search for genes whose deletions confer sensitivity to HAP and AHA in yeast. Results We screened the library of yeast deletion mutants for sensitivity to the toxic and mutagenic action of HAP and AHA. We identified novel genes involved in the genetic control of base analogs sensitivity, including genes controlling purine metabolism, cytoskeleton organization, and amino acid metabolism. Conclusion We developed a method for screening the yeast deletion library for sensitivity to the mutagenic and toxic action of base analogs and identified 16 novel genes controlling pathways of protection from HAP. Three of them also protect from AHA.

  11. NMR and molecular modeling evidence for a G·A mismatch base pair in a purine-rich DNA duplex

    International Nuclear Information System (INIS)

    Li, Ying; Wilson, W.D.; Zon, G.

    1991-01-01

    1 H NMR experiments indicate that the oligomer 5'-d(ATGAGCGAATA) forms an unusual 10-base-pair duplex with 4 G·A base pairs and a 3' unpaired adenosine. NMR results indicate that guanoxine imino protons of the F·A mismatches are not hydrogen bonded but are stacked in the helix. A G→ I substitution in either G·A base pair causes a dramatic decrtease in duplex stability and indicates that hydrogen bonding of the guanosine amino group is critical. Nuclear Overhauser effect spectroscopy (NOESY) and two-dimensional correlated spectroscopy (COSY) results indicate that the overall duplex conformation is in the B-family. Cross-strand NOEs in two-dimensional NOESY spectra between a mismatched AH2 and an AH1' of the other mismatched base pair and between a mismatched GH8 and GNH1 of the other mismatch establish a purine-purine stacking pattern, adenosine over adenosine and guanosine over guanosine, which strongly stabilizes the duplex. A computer graphics molecular model of the ususual duplex was constructed with G·A base pairs containing A-NH 2 to GN3 and G-NH 2 to AN7 hydrogen bonds and B-form base pairs on both sides of the G·A pairs [5'-d(ATGAGC)]. The energy-minimized duplex satisfies all experimental constraints from NOESY and COSY results. A hydrogen bond from G-NH 2 of the mismatch to a phosphate oxygen is predicted

  12. Errores innatos del metabolismo de las purinas y otras enfermedades relacionadas Inborn purine metabolism errors and other related diseases

    Directory of Open Access Journals (Sweden)

    Jiovanna Contreras Roura

    2012-06-01

    Full Text Available Los errores innatos en el metabolismo de las purinas son trastornos hereditarios complejos de gran impacto clínico, que presentan síntomas variables de acuerdo con el tipo de enfermedad. Pueden presentarse problemas renales de origen desconocido, retardo mental con manifestaciones neurológicas, retardo del crecimiento, infecciones recurrentes, automutilación, inmunodeficiencias, anemia hemolítica inexplicable, artritis gotosa, historia familiar, consanguinidad y reacciones adversas a fármacos que son análogos de las purinas. Las investigaciones de estas enfermedades comienzan generalmente con la cuantificación del ácido úrico en suero y en orina, por ser el producto final del metabolismo de las purinas en humanos. La dieta y el consumo de medicamentos, entre otras condiciones patológicas, fisiológicas y clínicas, también pueden modificar los niveles de este compuesto. Esta revisión pretende divulgar información de los errores innatos en el metabolismo de las purinas, y facilitar la interpretación de los niveles del ácido úrico y otros marcadores bioquímicos útiles en el diagnóstico de estas enfermedades. Se incluyen tablas que relacionan estas enfermedades con los niveles de excreción de ácido úrico y otros marcadores bioquímicos, las enzimas alteradas, los síntomas clínicos, el modo de herencia y, en algunos casos, el tratamiento propuesto. Este trabajo nos permite afirmar que las variaciones en los niveles del ácido úrico y la presencia de otros marcadores bioquímicos en orina, constituyen una herramienta importante en la pesquisa de algunos errores innatos en el metabolismo de las purinas, así como de otras condiciones patológicas relacionadas.Inborn purine metabolism errors are complex inherited disorders of great clinical impact that present with variable symptoms according to the type of disease. It might occur renal problems of unknown origin, metal retardation with neurological manifestations, retarded

  13. Long term expression of Drosophila melanogaster nucleoside kinase in thymidine kinase 2-deficient mice with no lethal effects caused by nucleotide pool imbalances.

    Science.gov (United States)

    Krishnan, Shuba; Paredes, João A; Zhou, Xiaoshan; Kuiper, Raoul V; Hultenby, Kjell; Curbo, Sophie; Karlsson, Anna

    2014-11-21

    Mitochondrial DNA depletion caused by thymidine kinase 2 (TK2) deficiency can be compensated by a nucleoside kinase from Drosophila melanogaster (Dm-dNK) in mice. We show that transgene expression of Dm-dNK in Tk2 knock-out (Tk2(-/-)) mice extended the life span of Tk2(-/-) mice from 3 weeks to at least 20 months. The Dm-dNK(+/-)Tk2(-/-) mice maintained normal mitochondrial DNA levels throughout the observation time. A significant difference in total body weight due to the reduction of subcutaneous and visceral fat in the Dm-dNK(+/-)Tk2(-/-) mice was the only visible difference compared with control mice. This indicates an effect on fat metabolism mediated through residual Tk2 deficiency because Dm-dNK expression was low in both liver and fat tissues. Dm-dNK expression led to increased dNTP pools and an increase in the catabolism of purine and pyrimidine nucleotides but these alterations did not apparently affect the mice during the 20 months of observation. In conclusion, Dm-dNK expression in the cell nucleus expanded the total dNTP pools to levels required for efficient mitochondrial DNA synthesis, thereby compensated the Tk2 deficiency, during a normal life span of the mice. The Dm-dNK(+/-) mouse serves as a model for nucleoside gene or enzyme substitutions, nucleotide imbalances, and dNTP alterations in different tissues. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Palindromic nucleotide analysis in human T cell receptor rearrangements.

    Directory of Open Access Journals (Sweden)

    Santosh K Srivastava

    Full Text Available Diversity of T cell receptor (TCR genes is primarily generated by nucleotide insertions upon rearrangement from their germ line-encoded V, D and J segments. Nucleotide insertions at V-D and D-J junctions are random, but some small subsets of these insertions are exceptional, in that one to three base pairs inversely repeat the sequence of the germline DNA. These short complementary palindromic sequences are called P nucleotides. We apply the ImmunoSeq deep-sequencing assay to the third complementarity determining region (CDR3 of the β chain of T cell receptors, and use the resulting data to study P nucleotides in the repertoire of naïve and memory CD8(+ and CD4(+ T cells. We estimate P nucleotide distributions in a cross section of healthy adults and different T cell subtypes. We show that P nucleotide frequency in all T cell subtypes ranges from 1% to 2%, and that the distribution is highly biased with respect to the coding end of the gene segment. Classification of observed palindromic sequences into P nucleotides using a maximum conditional probability model shows that single base P nucleotides are very rare in VDJ recombination; P nucleotides are primarily two bases long. To explore the role of P nucleotides in thymic selection, we compare P nucleotides in productive and non-productive sequences of CD8(+ naïve T cells. The naïve CD8(+ T cell clones with P nucleotides are more highly expanded.

  15. Wobble↔Watson-Crick tautomeric transitions in the homo-purine DNA mismatches: a key to the intimate mechanisms of the spontaneous transversions.

    Science.gov (United States)

    Brovarets', Ol'ha O; Hovorun, Dmytro M

    2015-01-01

    The intrinsic capability of the homo-purine DNA base mispairs to perform wobble↔Watson-Crick/Topal-Fresco tautomeric transitions via the sequential intrapair double proton transfer was discovered for the first time using QM (MP2/DFT) and QTAIM methodologies that are crucial for understanding the microstructural mechanisms of the spontaneous transversions.

  16. Cyclotrimerization of 6-ethynylpurines. Synthesis of 1,2,4- and 1,3,5-tris(purin-6-yl)benzenes as novel Hoogsteen-triplet analogues

    Czech Academy of Sciences Publication Activity Database

    Hocek, Michal; Stará, Irena G.; Starý, Ivo; Dvořáková, H.

    2001-01-01

    Roč. 42, č. 3 (2001), s. 519-521 ISSN 0040-4039 R&D Projects: GA ČR GA203/00/0036; GA ČR GA203/99/1448 Institutional research plan: CEZ:AV0Z4055905 Keywords : purines * cyclotrimerizations Subject RIV: CC - Organic Chemistry Impact factor: 2.280, year: 2001

  17. Anti-proliferative activity of 2,6-dichloro-9- or 7-(ethoxycarbonylmethyl)-9H- or 7H-purines against several human solid tumour cell lines.

    Science.gov (United States)

    Morales, Fátima; Ramírez, Alberto; Conejo-García, Ana; Morata, Cynthia; Marchal, Juan A; Campos, Joaquín M

    2014-04-09

    As leads we took several benzo-fused seven- and six-membered scaffolds linked to the pyrimidine or purine moieties with notable anti-proliferative activity against human breast, colon and melanoma cancerous cell lines. We then decided to maintain the double-ringed nitrogenous bases and change the other components to the ethyl acetate moiety. This way six purine and two 5-fluorouracil derivatives were obtained and evaluated against the MCF-7, HCT-116, A-375 and G-361 cancer cell lines. Two QSARs are obtained between the anti-proliferative IC₅₀ values for compounds 26-33 and the clog P against the melanoma cell lines A-375 and G-361. Our results show that two of the analogues [ethyl 2-(2,6-dichloro-9H- or 7H-purine-9- or 7-yl)acetates (30 and 33, respectively)] are potent cytotoxic agents against all the tumour cell lines assayed, showing single-digit micromolar IC₅₀ values. This exemplifies the potential of our previously reported purine compounds to qualify as lead structures for medicinal chemistry campaigns, affording simplified analogues easy to synthesize and with a noteworthy bioactivity. The selective activity of 30 and 33 against the melanoma cell line A-375, via apoptosis, supposes a great advantage for a future therapeutic use. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  18. A quantitative histochemical procedure for the demonstration of purine nucleoside phosphorylase activity in rat and human liver using Tetranitro BT and xanthine oxidase as auxiliary enzyme

    NARCIS (Netherlands)

    Frederiks, W. M.; Bosch, K. S.; van Gulik, T.

    1993-01-01

    A quantitative histochemical procedure was developed for the demonstration of purine nucleoside phosphorylase in rat liver using unfixed cryostat sections and the auxiliary enzyme xanthine oxidase. The optimum incubation medium contained 18% (w/v) poly(vinyl alcohol), 100 mM phosphate buffer, pH

  19. Influence of oxidized purine processing on strand directionality of mismatch repair.

    Science.gov (United States)

    Repmann, Simone; Olivera-Harris, Maite; Jiricny, Josef

    2015-04-17

    Replicative DNA polymerases are high fidelity enzymes that misincorporate nucleotides into nascent DNA with a frequency lower than [1/10(5)], and this precision is improved to about [1/10(7)] by their proofreading activity. Because this fidelity is insufficient to replicate most genomes without error, nature evolved postreplicative mismatch repair (MMR), which improves the fidelity of DNA replication by up to 3 orders of magnitude through correcting biosynthetic errors that escaped proofreading. MMR must be able to recognize non-Watson-Crick base pairs and excise the misincorporated nucleotides from the nascent DNA strand, which carries by definition the erroneous genetic information. In eukaryotes, MMR is believed to be directed to the nascent strand by preexisting discontinuities such as gaps between Okazaki fragments in the lagging strand or breaks in the leading strand generated by the mismatch-activated endonuclease of the MutL homologs PMS1 in yeast and PMS2 in vertebrates. We recently demonstrated that the eukaryotic MMR machinery can make use also of strand breaks arising during excision of uracils or ribonucleotides from DNA. We now show that intermediates of MutY homolog-dependent excision of adenines mispaired with 8-oxoguanine (G(O)) also act as MMR initiation sites in extracts of human cells or Xenopus laevis eggs. Unexpectedly, G(O)/C pairs were not processed in these extracts and failed to affect MMR directionality, but extracts supplemented with exogenous 8-oxoguanine DNA glycosylase (OGG1) did so. Because OGG1-mediated excision of G(O) might misdirect MMR to the template strand, our findings suggest that OGG1 activity might be inhibited during MMR. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Coupling of guanine nucleotide inhibitory protein to somatostatin receptors on pancreatic acinar membranes

    International Nuclear Information System (INIS)

    Sakamoto, C.; Matozaki, T.; Nagao, M.; Baba, S.

    1987-01-01

    Guanine nucleotides and pertussis toxin were used to investigate whether somatostatin receptors interact with the guanine nucleotide inhibitory protein (NI) on pancreatic acinar membranes in the rat. Guanine nucleotides reduced 125 I-[Tyr 1 ]somatostatin binding to acinar membranes up to 80%, with rank order of potency being 5'-guanylyl imidodiphosphate [Gpp(NH)p]>GTP>TDP>GMP. Scatchard analysis revealed that the decrease in somatostatin binding caused by Gpp(NH)p was due to the decrease in the maximum binding capacity without a significant change in the binding affinity. The inhibitory effect of Gpp(NH)p was partially abolished in the absence of Mg 2+ . When pancreatic acini were treated with 1 μg/ml pertussis toxin for 4 h, subsequent 125 I-[Tyr 1 ]somatostatin binding to acinar membranes was reduced. Pertussis toxin treatment also abolished the inhibitory effect of somatostatin on vasoactive intestinal peptide-stimulated increase in cellular content of adenosine 3',5'-cyclic monophosphate (cAMP) in the acini. The present results suggest that 1) somatostatin probably functions in the pancreas to regulate adenylate cyclase enzyme system via Ni, 2) the extent of modification of Ni is correlated with the ability of somatostatin to inhibit cAMP accumulation in acini, and 3) guanine nucleotides also inhibit somatostatin binding to its receptor

  1. Rasp21 sequences opposite the nucleotide binding pocket are required for GRF-mediated nucleotide release

    DEFF Research Database (Denmark)

    Leonardsen, L; DeClue, J E; Lybaek, H

    1996-01-01

    The substrate requirements for the catalytic activity of the mouse Cdc25 homolog Guanine nucleotide Release Factor, GRF, were determined using the catalytic domain of GRF expressed in insect cells and E. coli expressed H-Ras mutants. We found a requirement for the loop 7 residues in Ras (amino ac...... and the human Ras like proteins RhoA, Rap1A, Rac1 and G25K revealed a strict Ras specificity; of these only S. pombe Ras was GRF sensitive....

  2. Cyclic nucleotide specific phosphodiesterases of Leishmania major

    Directory of Open Access Journals (Sweden)

    Linder Markus

    2006-03-01

    Full Text Available Abstract Background Leishmania represent a complex of important human pathogens that belong to the systematic order of the kinetoplastida. They are transmitted between their human and mammalian hosts by different bloodsucking sandfly vectors. In their hosts, the Leishmania undergo several differentiation steps, and their coordination and optimization crucially depend on numerous interactions between the parasites and the physiological environment presented by the fly and human hosts. Little is still known about the signalling networks involved in these functions. In an attempt to better understand the role of cyclic nucleotide signalling in Leishmania differentiation and host-parasite interaction, we here present an initial study on the cyclic nucleotide-specific phosphodiesterases of Leishmania major. Results This paper presents the identification of three class I cyclic-nucleotide-specific phosphodiesterases (PDEs from L. major, PDEs whose catalytic domains exhibit considerable sequence conservation with, among other, all eleven human PDE families. In contrast to other protozoa such as Dictyostelium, or fungi such as Saccharomyces cerevisiae, Candida ssp or Neurospora, no genes for class II PDEs were found in the Leishmania genomes. LmjPDEA contains a class I catalytic domain at the C-terminus of the polypeptide, with no other discernible functional domains elsewhere. LmjPDEB1 and LmjPDEB2 are coded for by closely related, tandemly linked genes on chromosome 15. Both PDEs contain two GAF domains in their N-terminal region, and their almost identical catalytic domains are located at the C-terminus of the polypeptide. LmjPDEA, LmjPDEB1 and LmjPDEB2 were further characterized by functional complementation in a PDE-deficient S. cerevisiae strain. All three enzymes conferred complementation, demonstrating that all three can hydrolyze cAMP. Recombinant LmjPDEB1 and LmjPDEB2 were shown to be cAMP-specific, with Km values in the low micromolar range

  3. Feed intake and urinary excretion of nitrogen and purine derivatives in pregnant suckler cows fed alternative roughage-based diets

    DEFF Research Database (Denmark)

    Jardstedt, M.; Hessle, A.; Nørgaard, P.

    2017-01-01

    This study compared intake of alternative roughage-based diets and of common late-cut grass silage and related intake to urinary nitrogen (N), urea-N and purine derivative (PD) excretion, where PD is an indicator of rumen microbial crude protein (MCP) synthesis. Total urine was collected from 36...... Hereford cows, blocked into three groups based on expected calving date. Cows within calving groups were randomly assigned to one of four roughage diets: common mixed grass silage (MGS), festulolium silage plus urea (FLS), reed canarygrass silage (RCS) and barley straw plus urea and rapeseed meal (BRM...... diets stimulated rumen MCP production to a greater extent than the BRM diet, as indicated by the higher urinary output of PD in cows fed the grass silage-based diets (P

  4. Effect of benzyl amino purine and indole-3-acetic acid on propagation of Sterculia foetida in vitro

    Science.gov (United States)

    Yuniastuti, E.; Widodo, C. E.; Samanhudi; Delfianti, M. N. I.

    2018-03-01

    Sterculia foetida is an oval seed plants that can be used as biofuel, which is one of the environmental friendly fuels. This plant is quite hard to find because not many peoples cultivate the plants. An in vitro propagation is one way to preserve the plant. This research aimed to determine optimum concentration of benzyl amino purine (BAP) and indole-3-acetic acid (IAA) to propagate S. foetida in vitro. The results showed that woody plant medium (WPM) added by 4 mg L BAP-1 and 0.5 mg L IAA-1 was able to produce complete plantlet, whereas those added by 4 mg L BAP-1 and 1 mg L IAA-1 generated the best growth of shoot and leaves.

  5. Purine biosynthesis in L1210 leukemia cells is inhibited by 7-hydroxymethotrexate (7-OH-MTX) polyglutamates (PGS)

    International Nuclear Information System (INIS)

    Seither, R.L.; Matherly, L.H.; Goldman, I.D.

    1986-01-01

    The biochemical basis for 7-OH-MTX cytotoxicity was examined in L1210 tumor cells. Cells were exposed to 100 μM 7-OH-MTX (approx. 50% growth inhibition) or 10 μM methotrexate (MTX) (approx. 95% growth inhibition) for 6 hrs to allow high levels of PGS to accumulate. Dihydrofolate reductase (DHFR) activity was assessed by dihydrofolate (FH 2 ) pools labeled with 5-formyl-[ 3 H]-tetrahydrofolate (5μM) or 3 H-folic acid (1 μM). FH 2 was not elevated above control levels in 7-OH-MTX treated cells, in contrast to MTX treated cells in which FH 2 increased 4- to 7-fold. 3 H-Deoxyuridine incorporation into DNA was not inhibited in cells containing high levels (11.5 nmol/g dry wt.) of 7-OH-MTX tetraglutamate (7-OH-4-NH 2 -10-CH 3 -PteGlu 4 ), well in excess of the DHFR-binding capacity (7.3 +/- 0.9 nmol/g), indicating a normal rate of thymidylate synthesis. Although small amounts of 7-OH-MTX and its PGS were bound to DHFR in L1210 cells, as assessed by gel filtration, there was evidence for the preferential binding of 7-OH-MTX tetraglutamate. In all cases this was well below the DHFR binding capacity, consistent with normal rates of deoxyuridine metabolism and FH 2 levels in the cell. Incorporation of 14 C-formate (60 min) into thymidylate and amino acids was unaffected by 7-OH-MTX, yet incorporation into purines was inhibited over 50%, supporting a block(s) in de novo purine biosynthesis

  6. Synthesis 1-(5-oxohexyl)-3,7-dimethyl-xanthyne labelled with tritium into 8 position from purinic ring

    International Nuclear Information System (INIS)

    Mihaila, V.; Corol, D.

    1999-01-01

    This paper presents the work on synthesis of 1-(5-oxohexyl)-3,7-dimethyl-xanthyne labelled with tritium into 8 position from purinic ring. The obtaining of tritium labelled compound is realized by initial labelling of theobromine with tritium into 8 position and by coupling the purinic derivative to 1-Br-5-hexanone. Theobromine-8- 3 H was obtained by the bromination of theobromine with elementary bromine and after that the bromine was substituted with tritium i.e.: C 7 H 8 O 2 N 4 theobromine Br 2 /(-HBr) C 7 H 7 O 2 N 4 Br (8-Br-theobromine) ( 3 H 2 /cat)/(-KOH) C 7 H 7 3 HO 2 N 4 (theobromine-8- 3 H). Theobromine-8- 3 H was purified by thin layer chromatography with a solvent system i.e. n-BuOH:AcOH:H 2 O (4:1:1, v/v/v) and characterized radiochemically. It was then diluted by unlabelled theobromine to specific activity of 50 mCi/g. After dilution, theobromine-8- 3 H was coupled to 1-Br-5-hexanone i.e.: C 7 H 7 3 HO 2 N 4 (theobromine-8- 3 H) + Br-(CH 2 ) 4 -CO-CH 3 (1-Br-5-hexanone) (NaOH)/(CH 3 OH) C 13 H 17 3 HO 3 N 4 (1-(5-oxohexyl)- 3,7-dimethyl-xanthine-8- 3 H). The raw compound was purified by recrystallization from 2-propanol and it was characterized radiochemically. (authors)

  7. Regulation of ribonucleotide reductase by Spd1 involves multiple mechanisms

    DEFF Research Database (Denmark)

    Nestoras, Konstantinos; Mohammed, Asma Hadi; Schreurs, Ann-Sofie

    2010-01-01

    The correct levels of deoxyribonucleotide triphosphates and their relative abundance are important to maintain genomic integrity. Ribonucleotide reductase (RNR) regulation is complex and multifaceted. RNR is regulated allosterically by two nucleotide-binding sites, by transcriptional control, and...

  8. Supplementary Material for: The arabidopsis cyclic nucleotide interactome

    KAUST Repository

    Donaldson, Lara; Meier, Stuart; Gehring, Christoph A

    2016-01-01

    Abstract Background Cyclic nucleotides have been shown to play important signaling roles in many physiological processes in plants including photosynthesis and defence. Despite this, little is known about cyclic nucleotide-dependent signaling mechanisms in plants since the downstream target proteins remain unknown. This is largely due to the fact that bioinformatics searches fail to identify plant homologs of protein kinases and phosphodiesterases that are the main targets of cyclic nucleotides in animals. Methods An affinity purification technique was used to identify cyclic nucleotide binding proteins in Arabidopsis thaliana. The identified proteins were subjected to a computational analysis that included a sequence, transcriptional co-expression and functional annotation analysis in order to assess their potential role in plant cyclic nucleotide signaling. Results A total of twelve cyclic nucleotide binding proteins were identified experimentally including key enzymes in the Calvin cycle and photorespiration pathway. Importantly, eight of the twelve proteins were shown to contain putative cyclic nucleotide binding domains. Moreover, the identified proteins are post-translationally modified by nitric oxide, transcriptionally co-expressed and annotated to function in hydrogen peroxide signaling and the defence response. The activity of one of these proteins, GLYGOLATE OXIDASE 1, a photorespiratory enzyme that produces hydrogen peroxide in response to Pseudomonas, was shown to be repressed by a combination of cGMP and nitric oxide treatment. Conclusions We propose that the identified proteins function together as points of cross-talk between cyclic nucleotide, nitric oxide and reactive oxygen species signaling during the defence response.

  9. In-silico single nucleotide polymorphisms (SNP) mining of Sorghum ...

    African Journals Online (AJOL)

    Single nucleotide polymorphisms (SNPs) may be considered the ultimate genetic markers as they represent the finest resolution of a DNA sequence (a single nucleotide), and are generally abundant in populations with a low mutation rate. SNPs are important tools in studying complex genetic traits and genome evolution.

  10. Condensing the information in DNA with double-headed nucleotides

    DEFF Research Database (Denmark)

    Hornum, Mick; Sharma, Pawan K; Reslow-Jacobsen, Charlotte

    2017-01-01

    A normal duplex holds as many Watson-Crick base pairs as the number of nucleotides in its constituent strands. Here we establish that single nucleotides can be designed to functionally imitate dinucleotides without compromising binding affinity. This effectively allows sequence information...

  11. Implication of SUMO E3 ligases in nucleotide excision repair.

    Science.gov (United States)

    Tsuge, Maasa; Kaneoka, Hidenori; Masuda, Yusuke; Ito, Hiroki; Miyake, Katsuhide; Iijima, Shinji

    2015-08-01

    Post-translational modifications alter protein function to mediate complex hierarchical regulatory processes that are crucial to eukaryotic cellular function. The small ubiquitin-like modifier (SUMO) is an important post-translational modification that affects transcriptional regulation, nuclear localization, and the maintenance of genome stability. Nucleotide excision repair (NER) is a very versatile DNA repair system that is essential for protection against ultraviolet (UV) irradiation. The deficiencies in NER function remarkably increase the risk of skin cancer. Recent studies have shown that several NER factors are SUMOylated, which influences repair efficiency. However, how SUMOylation modulates NER has not yet been elucidated. In the present study, we performed RNAi knockdown of SUMO E3 ligases and found that, in addition to PIASy, the polycomb protein Pc2 affected the repair of cyclobutane pyrimidine dimers. PIAS1 affected both the removal of 6-4 pyrimidine pyrimidone photoproducts and cyclobutane pyrimidine dimers, whereas other SUMO E3 ligases did not affect the removal of either UV lesion.

  12. Domestication rewired gene expression and nucleotide diversity patterns in tomato.

    Science.gov (United States)

    Sauvage, Christopher; Rau, Andrea; Aichholz, Charlotte; Chadoeuf, Joël; Sarah, Gautier; Ruiz, Manuel; Santoni, Sylvain; Causse, Mathilde; David, Jacques; Glémin, Sylvain

    2017-08-01

    Plant domestication has led to considerable phenotypic modifications from wild species to modern varieties. However, although changes in key traits have been well documented, less is known about the underlying molecular mechanisms, such as the reduction of molecular diversity or global gene co-expression patterns. In this study, we used a combination of gene expression and population genetics in wild and crop tomato to decipher the footprints of domestication. We found a set of 1729 differentially expressed genes (DEG) between the two genetic groups, belonging to 17 clusters of co-expressed DEG, suggesting that domestication affected not only individual genes but also regulatory networks. Five co-expression clusters were enriched in functional terms involving carbohydrate metabolism or epigenetic regulation of gene expression. We detected differences in nucleotide diversity between the crop and wild groups specific to DEG. Our study provides an extensive profiling of the rewiring of gene co-expression induced by the domestication syndrome in one of the main crop species. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  13. SYNTHESIS OF NEW TWO DERIVATIVES OF 6-MERCAPTOPURINE (6MP) 6-[5-PYRIDINE-4-YL- 1, 2, 3, 4-OXADIAZOLE-2-YL)DITHIOL]-9H-PURINE (38) AND 9H-PURINE-6-YL-BENYLDITHIOCARBAMATE (45) WITH CYTOTOXICITY RESULTS FROM THE NATIONAL CANCER INSTITUTE'S ANTICANCER DRUG SCREEN

    OpenAIRE

    Mohammed Hassan Mohammed et al

    2012-01-01

    6-[(5-pyridine-yl-1, 2, 3, 4-oxadiazole-2-yl)dithiol]-9H-purine (38) and 9H-purine-6yl-benzyldithiocarbamate (45) are synthesized as possible prodrugs for 6-mercaptopurine(6-MP). The generation of the compounds 38, 42, 45 and 48 were accomplished following multistep reaction procedures. The reaction and purity of the products were checked by TLC, the structure of the final compounds and their intermediates were confirmed by their melting points, infra red spectroscopy and whether differences ...

  14. Adenine nucleotide depletion from endothelial cells exposed to xanthine oxidase

    International Nuclear Information System (INIS)

    Aalto, T.K.; Raivio, K.O.

    1990-01-01

    Hypoxia causes breakdown of cellular nucleotides, accumulation of hypoxanthine (HX), and conversion of xanthine dehydrogenase into xanthine oxidase (XO). Upon reoxygenation, the HX-XO reaction generates free radicals, one potential mechanism of tissue damage. Because endothelial cells contain XO and are exposed to circulating HX, they are a likely target for damage. We studied the effect of XO and/or HX at physiologically relevant concentrations on nucleotide metabolism of cultured endothelial cells from human umbilical veins. Cells were labeled with [14C]adenine and incubated for up to 6 h with HX, XO, or both, in the absence or presence of serum. Adenine nucleotides from cell extracts and nucleotide breakdown products (HX, xanthine, and urate) from the medium were separated and counted. HX alone had no effect. XO (80 mU/ml) alone caused a 70% (no serum) or 40% (with serum) fall in adenine nucleotides and an equivalent increase of xanthine and urate. The combination of HX and XO caused a 90% (no serum) or 70% (with serum) decrease in nucleotides, decrease in energy charge, and detachment of cells from the culture plate. Nucleotide depletion was not accounted for by proteolytic activity in the XO preparation. Albumin was only half as effective as serum in preventing nucleotide loss. Thus exogenous XO, in the presence of endogenous HX, triggers adenine nucleotide catabolism, but endogenous XO activity is too low to influence nucleotide levels even at high exogenous HX concentrations. Serum limits the catabolic effect of XO and thus protects cells from free radical damage

  15. Molecular cloning and complete nucleotide sequence of a human ventricular myosin light chain 1

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, E; Shi, Q W; Floroff, M; Mickle, D A.G.; Wu, T W; Olley, P M; Jackowski, G

    1988-03-25

    Human ventricular plasmid library was constructed. The library was screened with the oligonucleotide probe (17-mer) corresponding to a conserve region of myosin light chain 1 near the carboxy terminal. Full length cDNA recombinant plasmid containing 1100 bp insert was isolated. RNA blot hybridization with this insert detected a message of approximately 1500 bp corresponding to the size of VLCl and mRNA. Complete nucleotide sequence of the coding region was determined in M13 subclones using dideoxy chain termination method. With the isolation of this clone (pCD HLVCl), the publication of the complete nucleotide sequence of HVLCl and the predicted secondary structure of this protein will aid in understanding of the biochemistry of myosin and its function in contraction, the evolution of myosin light genes and the genetic, developmental and physiological regulation of myosin genes.

  16. Effect of ionizing radiation on calcium and cyclic nucleotides metabolism in rats of different age

    International Nuclear Information System (INIS)

    Efimova, N.I.; Libenson, S.V.

    1982-01-01

    Some features of mechanism of calcium homeostasis and cyclic nucleotide exchange breakage in case of acute radiation injury of rats of various age were studied. It is established that calcium level in blood in nonpuberal animals, calcium and cAMP excretion with urine are minimal and reach maximum at puberal age. cGMP excretion with urine and concentrational levels of cAMP and cGMP in blood do not change with age. It is shown that calcium excretion with urine decreases adaptively in conditions of acute radiation injury in rats of all age groups. Maximal shifts in cAMP/cGMP ratio were noted in nonpuberal animals, whereas maximal adaptive-compensatory abilities in the regulation system of calcium homeostasis and cyclic nucleotides are typical to adolescent puberal animals

  17. The effect of nucleotides and adenosine on stimulus-evoked glutamate release from rat brain cortical slices

    OpenAIRE

    Bennett, Gillian C; Boarder, Michael R

    2000-01-01

    Evidence has previously been presented that P1 receptors for adenosine, and P2 receptors for nucleotides such as ATP, regulate stimulus-evoked release of biogenic amines from nerve terminals in the brain. Here we investigated whether adenosine and nucleotides exert presynaptic control over depolarisation-elicited glutamate release.Slices of rat brain cortex were perfused and stimulated with pulses of 46 mM K+ in the presence of the glutamate uptake inhibitor L-trans-pyrrolidine-2,4-dicarboxyl...

  18. Nucleotide excision repair in differentiated cells

    Energy Technology Data Exchange (ETDEWEB)

    Wees, Caroline van der [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Department of Cardiology, Leiden University Medical Center, Leiden (Netherlands); Jansen, Jacob [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Vrieling, Harry [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Laarse, Arnoud van der [Department of Cardiology, Leiden University Medical Center, Leiden (Netherlands); Zeeland, Albert van [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Mullenders, Leon [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands)]. E-mail: l.mullenders@lumc.nl

    2007-01-03

    Nucleotide excision repair (NER) is the principal pathway for the removal of a wide range of DNA helix-distorting lesions and operates via two NER subpathways, i.e. global genome repair (GGR) and transcription-coupled repair (TCR). Although detailed information is available on expression and efficiency of NER in established mammalian cell lines, little is known about the expression of NER pathways in (terminally) differentiated cells. The majority of studies in differentiated cells have focused on repair of UV-induced cyclobutane pyrimidine dimers (CPD) and 6-4-photoproducts (6-4PP) because of the high frequency of photolesions at low level of toxicity and availability of sensitive technologies to determine photolesions in defined regions of the genome. The picture that emerges from these studies is blurred and rather complex. Fibroblasts and terminally differentiated myocytes of the rat heart display equally efficient GGR of 6-4PP but poor repair of CPD due to the absence of p48 expression. This repair phenotype is clearly different from human terminal differentiated neurons. Furthermore, both cell types were found to carry out TCR of CPD, thus mimicking the repair phenotype of established rodent cell lines. In contrast, in intact rat spermatogenic cells repair was very inefficient at the genome overall level and in transcriptionally active genes indicating that GGR and TCR are non-functional. Also, non-differentiated mouse embryonic stem (ES) cells exhibit low levels of NER after UV irradiation. However, the mechanisms that lead to low NER activity are clearly different: in differentiated spermatogenic cells differences in chromatin compaction and sequestering of NER proteins may underlie the lack of NER activity in pre-meiotic cells, whereas in non-differentiated ES cells NER is impaired by a strong apoptotic response.

  19. Postjunctional effects and neural release of purine compounds in the guinea-pig vas deferens

    Energy Technology Data Exchange (ETDEWEB)

    Westfall, D P; Stitzel, R E; Rowe, J N [West Virginia Univ., Morgantown (USA). Medical Center

    1978-07-01

    The smooth muscle of the in vitro guinea-pig vas deferens was shown to contract upon addition of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP), the order of potency being ATP>ADP>AMP. Adenosine did not produce contraction. Pretreatment of animals with reserpine or treatment of tissues with an ..cap alpha..-adrenoceptor blocking agent failed to alter the dose-response relationship for ATP. Because ATP is both a potent agent and is present in the adrenergic storage complex, evidence was sought for the role of ATP as a possible co-transmitter following neural stimulation. Tissues preincubated in /sup 3/H-adenosine, a procedure which results in the incorporation of label into /sup 3/H-adenine nucleotides in the vas deferens, released significant amounts of tritium upon transmural simulation. Because contraction per se can contribute to the tritium overflow, experiments were conducted with bathing solution made hypertonic with sucrose (12.5%). Hypertonic solution prevented the electrically induced tissue contraction, but failed to prevent a tetrodotoxin-sensitive release of tritium from tissue preincubated with either /sup 3/H-norepinephrine or /sup 3/H-adenosine. Because of the known association of ATP with norepinephrine in synaptic vesicles of adrenergic nerves and in view of the present evidence of a postjunctional action of ATP as well as the release of tritium from /sup 3/H-adenosine-treated vasa deferentia, it seems possible that in this tissue ATP, in addition to its other functions, may serve as a co-transmitter with norepinephrine.

  20. Nucleotide Excision Repair in Cellular Chromatin: Studies with Yeast from Nucleotide to Gene to Genome

    Directory of Open Access Journals (Sweden)

    Simon Reed

    2012-09-01

    Full Text Available Here we review our development of, and results with, high resolution studies on global genome nucleotide excision repair (GGNER in Saccharomyces cerevisiae. We have focused on how GGNER relates to histone acetylation for its functioning and we have identified the histone acetyl tranferase Gcn5 and acetylation at lysines 9/14 of histone H3 as a major factor in enabling efficient repair. We consider results employing primarily MFA2 as a model gene, but also those with URA3 located at subtelomeric sequences. In the latter case we also see a role for acetylation at histone H4. We then go on to outline the development of a high resolution genome-wide approach that enables one to examine correlations between histone modifications and the nucleotide excision repair (NER of UV-induced cyclobutane pyrimidine dimers throughout entire genomes. This is an approach that will enable rapid advances in understanding the complexities of how compacted chromatin in chromosomes is processed to access DNA damage and then returned to its pre-damaged status to maintain epigenetic codes.

  1. The possible role of human milk nucleotides as sleep inducers.

    Science.gov (United States)

    Sánchez, Cristina L; Cubero, Javier; Sánchez, Javier; Chanclón, Belén; Rivero, Montserrat; Rodríguez, Ana B; Barriga, Carmen

    2009-02-01

    Breast-milk contains a potent mixture of diverse components, such as the non-protein nitrogen fraction which includes nucleotides, whose variation in levels is evident throughout lactation. In addition, these substances play an important role in sleep homeostasis. In the present study, human milk samples were analyzed using a capillary electrophoresis system. The rhythmicity of each nucleotide was studied by cosinor analysis. It was found that the nucleotides 5'AMP, 5'GMP, 5'CMP, and 5'IMP have significant (P inducing the 'hypnotic' action of breast-milk at night in the infant.

  2. Nucleotide sequence of Hungarian grapevine chrome mosaic nepovirus RNA1.

    OpenAIRE

    Le Gall, O; Candresse, T; Brault, V; Dunez, J

    1989-01-01

    The nucleotide sequence of the RNA1 of hungarian grapevine chrome mosaic virus, a nepovirus very closely related to tomato black ring virus, has been determined from cDNA clones. It is 7212 nucleotides in length excluding the 3' terminal poly(A) tail and contains a large open reading frame extending from nucleotides 216 to 6971. The presumably encoded polyprotein is 2252 amino acids in length with a molecular weight of 250 kDa. The primary structure of the polyprotein was compared with that o...

  3. Synthesis of 9,9′-[1,2-Ethanediylbis(oxymethylene]bis-2-amino-1,9-dihydro-6H-purin-6-one, an Impurity of Acyclovir

    Directory of Open Access Journals (Sweden)

    Juan José Vaquero

    2012-07-01

    Full Text Available The synthesis of 9,9'-[1,2-ethanediylbis(oxymethylene]bis-2-amino-1,9-dihydro-6H-purin-6-one, a minor impurity of acyclovir, is described. Starting with commercial N-(9-acetyl-6-oxo-1H-purin-2-ylacetamide, the process uses an acid catalysed phase transfer catalysis (PTC process to produce the selective alkylation at the 9 position of the guanine ring.

  4. The immunosuppressives FK 506 and cyclosporin A inhibit the generation of protein factors binding to the two purine boxes of the interleukin 2 enhancer.

    Science.gov (United States)

    Brabletz, T; Pietrowski, I; Serfling, E

    1991-01-11

    Like Cyclosporin A (CsA), the macrolide FK 506 is a potent immunosuppressive that inhibits early steps of T cell activation, including the synthesis of Interleukin 2 (II-2) and numerous other lymphokines. The block of II-2 synthesis occurs at the transcriptional level. At concentrations that block T cell activation, FK 506 and CsA inhibit the proto-enhancer activity of Purine boxes of the II-2 promoter and the generation of lymphocyte-specific factors binding to the Purine boxes. Under the same conditions, the DNA binding of other II-2 enhancer factors remains unaffected by both compounds. These results support the view that FK 506 and CsA, which both inhibit the activity of peptidylprolyl cis/trans isomerases, suppress T cell activation by a similar, if not identical mechanism.

  5. Synthesis, Acidity Constants and Tautomeric Structure of the Diazonium Coupling Products of 2-(Benzylsulfanyl)-7H-purin-6-one in Its Ground and Excited States

    OpenAIRE

    Darwish, Elham S.; Mosselhi, Mosselhi A.; Altalbawy, Farag M.; Saad, Hosam A.

    2011-01-01

    A series of new 8-arylhydrazono-2-(benzylsulfanyl)-7H-purin-6-ones 6 were synthesized, their electronic absorption spectra in different organic solvents of varying polarities were investigated and their acid dissociation constants in both the ground and excited states were determined spectrophotometrically. The tautomeric structures of such products were elucidated by spectral analyses and correlation of their acid dissociation constants with the Hammett equation. The results indicated that t...

  6. Theoretical and experimental studies on the corrosion inhibition potentials of some purines for aluminum in 0.1 M HCl.

    Science.gov (United States)

    Eddy, Nnabuk O; Momoh-Yahaya, H; Oguzie, Emeka E

    2015-03-01

    Experimental aspect of the corrosion inhibition potential of adenine (AD), guanine (GU) and, hypoxanthine (HYP) was carried out using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods while the theoretical aspect of the work was carried out by calculations of semi-empirical parameters (for AM1, MNDO, CNDO, PM3 and RM1 Hamiltonians), Fukui functions and inhibitor-metal interaction energies. Results obtained from the experimental studies were in good agreement and indicated that adenine (AD), guanine (GU) and hypoxanthine (HYP) are good adsorption inhibitors for the corrosion of aluminum in solutions of HCl. Data obtained from electrochemical experiment revealed that the studied purines functioned by adsorption on the aluminum/HCl interface and inhibited the cathodic half reaction to a greater extent and anodic half reaction to a lesser extent. The adsorption of the purines on the metal surface was found to be exothermic and spontaneous. Deviation of the adsorption characteristics of the studied purines from the Langmuir adsorption model was compensated by the fitness of Flory Huggins and El Awardy et al. adsorption models. Quantum chemical studies revealed that the experimental inhibition efficiencies of the studied purines are functions of some quantum chemical parameters including total energy of the molecules (TE), energy gap (E L-H), electronic energy of the molecule (EE), dipole moment and core-core repulsion energy (CCR). Fukui functions analysis through DFT and MP2 theories indicated slight complications and unphysical results. However, results obtained from calculated Huckel charges, molecular orbital and interaction energies, the adsorption of the inhibitors proceeded through the imine nitrogen (N5) in GU, emanine nitrogen (N7) in AD and the pyridine nitrogen (N5) in HPY.

  7. The effect of novel [3-fluoro-(2-phosphonoethoxy)propyl]purines on the inhibition of Plasmodium falciparum, Plasmodium vivax and human hypoxanthine-guanine-(xanthine) phosphoribosyltransferases

    Czech Academy of Sciences Publication Activity Database

    Baszczyňski, Ondřej; Hocková, Dana; Janeba, Zlatko; Holý, Antonín; Jansa, Petr; Dračínský, Martin; Keough, D. T.; Guddat, L. W.

    2013-01-01

    Roč. 67, Sep (2013), s. 81-89 ISSN 0223-5234 R&D Projects: GA MV VG20102015046; GA ČR GAP207/11/0108 Grant - others:National Health and Madical Research Council(AU) 1030353; National Health and Medical Research Council(AU) 569703 Institutional support: RVO:61388963 Keywords : Malaria * nucleoside phosphonates * fluorine * purines * FPMP Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 3.432, year: 2013

  8. 2D QSAR studies of the inhibitory activity of a series of substituted purine derivatives against c-Src tyrosine kinase

    OpenAIRE

    Mukesh C. Sharma

    2016-01-01

    A series of 34 substituted purine analogues derivatives were subjected to quantitative structure-activity relationship analyses as inhibitors of c-Src tyrosine kinase. Partial least squares regression was applied to derive QSAR models, which were further validated for statistical significance by internal and external validation. The best QSAR model developed had a good predictive correlation coefficient (r2) of 0.8319, a significant cross-validated correlation coefficient (q2) of 0.7550, and ...

  9. N9-Substituted N(6)-[(3-methylbut-2-en-1-yl)amino]purine derivatives and their biological activity in selected cytokinin bioassays

    Czech Academy of Sciences Publication Activity Database

    Mik, V.; Szüčová, Lucie; Spíchal, Lukáš; Plíhal, O.; Nisler, Jaroslav; Zahajská, L.; Doležal, Karel; Strnad, Miroslav

    2011-01-01

    Roč. 19, č. 23 (2011), s. 7244-7251 ISSN 0968-0896 R&D Projects: GA MŠk ED0007/01/01; GA ČR GA522/09/1576 Keywords : N6-[(3-Methylbut-2-en-1-yl)amino]purine * Isopentenyladenine derivatives * N9-Substituted derivatives * Cytokinins * Cytokinin receptors Subject RIV: EF - Botanics Impact factor: 2.921, year: 2011

  10. Computational identification of candidate nucleotide cyclases in higher plants

    KAUST Repository

    Wong, Aloysius Tze; Gehring, Christoph A

    2013-01-01

    In higher plants guanylyl cyclases (GCs) and adenylyl cyclases (ACs) cannot be identified using BLAST homology searches based on annotated cyclic nucleotide cyclases (CNCs) of prokaryotes, lower eukaryotes, or animals. The reason is that CNCs

  11. A single nucleotide polymorphism (SNP) assay for population ...

    African Journals Online (AJOL)

    A single nucleotide polymorphism (SNP) assay for population stratification test ... phenotypes and unlinked candidate loci in case-control and cohort studies of ... Key words: Chinese, Japanese, population stratification, ancestry informative ...

  12. Mitochondrial DNA analysis reveals a low nucleotide diversity of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-06-17

    Jun 17, 2009 ... gene sequences of C. japonica in China to assess nucleotide sequence diversity (GenBank ... provide a scientific basis for the regional control of forestry .... population (AB015869) was downloaded from GenBank database.

  13. Extracellular nucleotide derivatives protect cardiomyctes against hypoxic stress

    DEFF Research Database (Denmark)

    Golan, O; Issan, Y; Isak, A

    2011-01-01

    assures cardioprotection. Treatment with extracellular nucleotides, or with tri/di-phosphate, administered under normoxic conditions or during hypoxic conditions, led to a decrease in reactive oxygen species production. CONCLUSIONS: Extracellular tri/di-phosphates are apparently the molecule responsible...

  14. Detection of DNA nucleotides on pretreated boron doped diamond electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Garbellini, Gustavo S.; Uliana, Carolina V.; Yamanaka, Hideko [UNESP, Araraquara, SP (Brazil). Inst. de Quimica

    2011-07-01

    The individual detection and equimolar mixture of DNA nucleotides guanosine monophosphate (GMP), adenosine monophosphate (AMP), thymidine (TMP) and cytidine (CMP) 5'-monophosphate using square wave voltammetry was performed on boron doped diamond (BDD) electrodes cathodically (Red-DDB) and anodically (Oxi-DDB) pretreated. The oxidation of individual DNA nucleotides was more sensitive on Oxi-BDD electrode. In a simultaneous detection of nucleotides, the responses of GMP, AMP, TMP and CMP were very adequate on both treated electrodes. Particularly, more sensitive and separate peaks for TMP and CMP on Oxi-BDD and Red-BDD electrodes, respectively, were observed after deconvolution procedure. The detection of nucleotides in aqueous solutions will certainly contribute for genotoxic evaluation of substances and hybridization reactions by immobilizing ss or ds-DNA on BDD surface. (author)

  15. Free amino acids and 5'-nucleotides in Finnish forest mushrooms.

    Science.gov (United States)

    Manninen, Hanna; Rotola-Pukkila, Minna; Aisala, Heikki; Hopia, Anu; Laaksonen, Timo

    2018-05-01

    Edible mushrooms are valued because of their umami taste and good nutritional values. Free amino acids, 5'-nucleotides and nucleosides were analyzed from four Nordic forest mushroom species (Lactarius camphoratus, Boletus edulis, Cantharellus cibarius, Craterellus tubaeformis) using high precision liquid chromatography analysis. To our knowledge, these taste components were studied for the first time from Craterellus tubaeformis and Lactarius camphoratus. The focus was on the umami amino acids and 5'-nucleotides. The free amino acid and 5'-nucleotide/nucleoside contents of studied species differed from each other. In all studied samples, umami amino acids were among five major free amino acids. The highest concentration of umami amino acids was on L. camphoratus whereas B. edulis had the highest content of sweet amino acids and C. cibarius had the highest content of bitter amino acids. The content of umami enhancing 5'-nucleotides were low in all studied species. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Efecto Antagónico in vitro de Actinomicetos Aislados de Purines de Chipaca (Bidens pilosa L. Frente a Phytophthora infestans (Mont de Bary In vitro Antagonistic Effect of Actinomycetes Isolated from Chipaca (Bidens pilosa L. Purins Against Phytophthora infestans (Mont de Bary

    Directory of Open Access Journals (Sweden)

    Yudy Astrid Fonseca Ardila

    2011-12-01

    Full Text Available Se estudió el efecto inhibidor de los actinomicetos presentes en purines o extractos fermentados de plantas de chipaca (Bidens pilosa L., sobre el crecimiento de Phytophthora infestans (Mont de Bary, causante del tizón tardío de la papa. Se elaboraron cuatro purines de flores, raíces, hojas-tallos y su mezcla. De estos purines se obtuvieron 25 aislamientos de actinomicetos, cada uno de los cuales se enfrentó con P. infestans en placas de medio de cultivo, utilizando la técnica de anillos de Gauze y estableciendo las concentraciones iniciales de esporas mediante conteos microscópicos en cámara de Neubauer. Los actinomicetos no crecieron en el purin de flores debido, posiblemente, a que en él no se utiliza suelo rizosférico o porque su pH (9 es mayor que el rango normal de crecimiento de estos microorganismos ( pH 6 -; 8. Se evidenció inhibición del crecimiento del oomycete por parte de 8 aislamientos de actinomicetos con porcentajes de inhibición entre 33,3 - 77,8%, provenientes de los purines de raíces, tallos-hojas y mezcla de partes de la planta. La mayor inhibición se obtuvo en los aislamientos AC001, AC010, AC011 y AC025 con conteos de 0,4, 6,0, 3,0, y 3,6 x10(5 esporas mL-1.Purins or liquid fermented extracts of chipaca (Bidens pilosa L. were prepared to establish the inhibitory effect of the actinomycetes found in such biopharmaceutical preparations on the growth of Phytophthora infestans (Mont de Bary, the causative of potato late blight disease. Four purins made from flowers, roots, leaf-steams and a mixture of them were prepared; 25 actinomycete isolates were obtained from these purins and their ability to resist challenge by P. infestans was ascertained in medium plates using the ring Gauze technique and establishing initial concentrations of spores by microscopic counting in Neubauer chamber. Actinomycetes did not grow in flower purin as rhizosphere soil was not used in its preparation or because this particular pH (9

  17. Purine-related metabolites and their converting enzymes are altered in frontal, parietal and temporal cortex at early stages of Alzheimer's disease pathology.

    Science.gov (United States)

    Alonso-Andrés, Patricia; Albasanz, José Luis; Ferrer, Isidro; Martín, Mairena

    2018-01-24

    Adenosine, hypoxanthine, xanthine, guanosine and inosine levels were assessed by HPLC, and the activity of related enzymes 5'-nucleotidase (5'-NT), adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) measured in frontal (FC), parietal (PC) and temporal (TC) cortices at different stages of disease progression in Alzheimer's disease (AD) and in age-matched controls. Significantly decreased levels of adenosine, guanosine, hypoxanthine and xanthine, and apparently less inosine, are found in FC from the early stages of AD; PC and TC show an opposing pattern, as adenosine, guanosine and inosine are significantly increased at least at determinate stages of AD whereas hypoxanthine and xanthine levels remain unaltered. 5'-NT is reduced in membranes and cytosol in FC mainly at early stages but not in PC, and only at advanced stages in cytosol in TC. ADA activity is decreased in AD when considered as a whole but increased at early stages in TC. Finally, PNP activity is increased only in TC at early stages. Purine metabolism alterations occur at early stages of AD independently of neurofibrillary tangles and β-amyloid plaques. Alterations are stage dependent and region dependent, the latter showing opposite patterns in FC compared with PC and TC. Adenosine is the most affected of the assessed purines. © 2018 International Society of Neuropathology.

  18. Statistical properties and fractals of nucleotide clusters in DNA sequences

    International Nuclear Information System (INIS)

    Sun Tingting; Zhang Linxi; Chen Jin; Jiang Zhouting

    2004-01-01

    Statistical properties of nucleotide clusters in DNA sequences and their fractals are investigated in this paper. The average size of nucleotide clusters in non-coding sequence is larger than that in coding sequence. We investigate the cluster-size distribution P(S) for human chromosomes 21 and 22, and the results are different from previous works. The cluster-size distribution P(S 1 +S 2 ) with the total size of sequential Pu-cluster and Py-cluster S 1 +S 2 is studied. We observe that P(S 1 +S 2 ) follows an exponential decay both in coding and non-coding sequences. However, we get different results for human chromosomes 21 and 22. The probability distribution P(S 1 ,S 2 ) of nucleotide clusters with the size of sequential Pu-cluster and Py-cluster S 1 and S 2 respectively, is also examined. In the meantime, some of the linear correlations are obtained in the double logarithmic plots of the fluctuation F(l) versus nucleotide cluster distance l along the DNA chain. The power spectrums of nucleotide clusters are also discussed, and it is concluded that the curves are flat and hardly changed and the 1/3 frequency is neither observed in coding sequence nor in non-coding sequence. These investigations can provide some insights into the nucleotide clusters of DNA sequences

  19. Synthesis and degradation of cyclic nucleotides in brain after a high dose of ionizing radiation

    International Nuclear Information System (INIS)

    Hunt, W.A.; Dalton, T.K.

    1981-01-01

    Previous data from our laboratory have indicated that a high dose of ionizing radiation can deplete the cyclic nucleotides guanosine 3',5'-cyclic monophosphate (cGMP) and adenosine 3',5'-cyclic monophosphate (cAMP) on several areas of the rat brain. cGMP is more sensitive to radiation than cAMP and does not recover for at least 24 h after irradiation. The response of cAMP is transient and recovery occurs within 4 h. The purpose of the present paper is to determine whether alternations in the activity of the synthetic and degradative enzymes that regulate cyclic nucleotide levels could account for the observed effects. Guanylate and adenylate cyclase and cGMP and cAMP phosphodiesterase activities were determined 10 min after irradiation with 10,000 rad of high-energy electrons. No alteration was detected under these experimental conditions. The data suggest that the reduction in cyclic nucleotides is not a direct effect on their metabolic enzymes and is probably secondary to some as yet-undefined action of radiation on the brain

  20. The nucleotide-binding domain of NLRC5 is critical for nuclear import and transactivation activity

    International Nuclear Information System (INIS)

    Meissner, Torsten B.; Li, Amy; Liu, Yuen-Joyce; Gagnon, Etienne; Kobayashi, Koichi S.

    2012-01-01

    Highlights: ► NLRC5 requires an intact NLS for its function as MHC class I transactivator. ► Nuclear presence of NLRC5 is required for MHC class I induction. ► Nucleotide-binding controls nuclear import and transactivation activity of NLRC5. -- Abstract: Major histocompatibility complex (MHC) class I and class II are crucial for the function of the human adaptive immune system. A member of the NLR (nucleotide-binding domain, leucine-rich repeat) protein family, NLRC5, has recently been identified as a transcriptional regulator of MHC class I and related genes. While a ‘master regulator’ of MHC class II genes, CIITA, has long been known, NLRC5 specifically associates with and transactivates the proximal promoters of MHC class I genes. In this study, we analyzed the molecular requirements of NLRC5 nuclear import and transactivation activity. We show that NLRC5-mediated MHC class I gene induction requires an intact nuclear localization signal and nuclear distribution of NLRC5. In addition, we find that the nucleotide-binding domain (NBD) of NLRC5 is critical not only for nuclear translocation but also for the transactivation of MHC class I genes. Changing the cellular localization of NLRC5 is likely to immediately impact MHC class I expression as well as MHC class I-mediated antigen presentation. NLRC5 may thus provide a promising target for the modulation of MHC class I antigen presentation, especially in the setting of transplant medicine.

  1. The Nucleotide Synthesis Enzyme CAD Inhibits NOD2 Antibacterial Function in Human Intestinal Epithelial Cells

    Science.gov (United States)

    Richmond, Amy L.; Kabi, Amrita; Homer, Craig R.; García, Noemí Marina; Nickerson, Kourtney P.; NesvizhskiI, Alexey I.; Sreekumar, Arun; Chinnaiyan, Arul M.; Nuñez, Gabriel; McDonald, Christine

    2013-01-01

    BACKGROUND & AIMS Polymorphisms that reduce the function of nucleotide-binding oligomerization domain (NOD)2, a bacterial sensor, have been associated with Crohn’s disease (CD). No proteins that regulate NOD2 activity have been identified as selective pharmacologic targets. We sought to discover regulators of NOD2 that might be pharmacologic targets for CD therapies. METHODS Carbamoyl phosphate synthetase/ aspartate transcarbamylase/dihydroorotase (CAD) is an enzyme required for de novo pyrimidine nucleotide synthesis; it was identified as a NOD2-interacting protein by immunoprecipitation-coupled mass spectrometry. CAD expression was assessed in colon tissues from individuals with and without inflammatory bowel disease by immunohistochemistry. The interaction between CAD and NOD2 was assessed in human HCT116 intestinal epithelial cells by immunoprecipitation, immunoblot, reporter gene, and gentamicin protection assays. We also analyzed human cell lines that express variants of NOD2 and the effects of RNA interference, overexpression and CAD inhibitors. RESULTS CAD was identified as a NOD2-interacting protein expressed at increased levels in the intestinal epithelium of patients with CD compared with controls. Overexpression of CAD inhibited NOD2-dependent activation of nuclear factor κB and p38 mitogen-activated protein kinase, as well as intracellular killing of Salmonella. Reduction of CAD expression or administration of CAD inhibitors increased NOD2-dependent signaling and antibacterial functions of NOD2 variants that are and are not associated with CD. CONCLUSIONS The nucleotide synthesis enzyme CAD is a negative regulator of NOD2. The antibacterial function of NOD2 variants that have been associated with CD increased in response to pharmacologic inhibition of CAD. CAD is a potential therapeutic target for CD. PMID:22387394

  2. Synthesis and Properties of a Novel Type of Acyclic Nucleoside Phosphonates: 2-(Purin-9-yl)ethoxyphenylphosphonic Acids

    Czech Academy of Sciences Publication Activity Database

    Hocková, Dana; Dračínský, Martin; Holý, Antonín

    -, č. 15 (2010), s. 2885-2892 ISSN 1434-193X R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleotides * phosphonates * cross-coupling Subject RIV: CC - Organic Chemistry Impact factor: 3.206, year: 2010

  3. Mesenchymal stem cells from different murine tissues have differential capacity to metabolize extracellular nucleotides.

    Science.gov (United States)

    Iser, Isabele C; Bracco, Paula A; Gonçalves, Carlos E I; Zanin, Rafael F; Nardi, Nance B; Lenz, Guido; Battastini, Ana Maria O; Wink, Márcia R

    2014-10-01

    Mesenchymal stem cells (MSCs) have shown a great potential for cell-based therapy and many different therapeutic purposes. Despite the recent advances in the knowledge of MSCs biology, their biochemical and molecular properties are still poorly defined. Ecto-nucleoside triphosphate diphosphohydrolases (E-NTPDases) and ecto-5'-nucleotidase (eNT/CD73) are widely expressed enzymes that hydrolyze extracellular nucleotides, generating an important cellular signaling cascade. Currently, studies have evidenced the relationship between the purinergic system and the development, maintenance, and differentiation of stem cells. The objective of this study is to identify the NTPDases and eNT/CD73 and compare the levels of nucleotide hydrolysis on MSCs isolated from different murine tissues (bone marrow, lung, vena cava, kidney, pancreas, spleen, skin, and adipose tissue). MSCs from all tissues investigated expressed the ectoenzymes at different levels. In MSCs from pancreas and adipose tissue, the hydrolysis of triphosphonucleosides was significantly higher when compared to the other cells. The diphosphonucleosides were hydrolyzed at a higher rate by MSC from pancreas when compared to MSC from other tissues. The differential nucleotide hydrolysis activity and enzyme expression in these cells suggests that MSCs play different roles in regulating the purinergic system in these tissues. Overall MSCs are an attractive adult-derived cell population for therapies, however, the fact that ecto-nucleotide metabolism can affect the microenvironment, modulating important events, such as immune response, makes the assessment of this metabolism an important part of the characterization of MSCs to be applied therapeutically. © 2014 Wiley Periodicals, Inc.

  4. Roles of phosphorylation and nucleotide binding domains in calcium transport by sarcoplasmic reticulum adenosinetriphosphatase

    International Nuclear Information System (INIS)

    Teruel, J.A.; Inesi, G.

    1988-01-01

    The roles of the phosphorylation (phosphorylated enzyme intermediate) and nucleotide binding domains in calcium transport were studied by comparing acetyl phosphate and ATP as substrates for the Ca 2+ -ATPase of sarcoplasmic reticulum vesicles. The authors found that the maximal level of phosphoenzyme obtained with either substrate is approximately 4 nmol/mg of protein, corresponding to the stoichiometry of catalytic sites in their preparation. The initial burst of phosphoenzyme formation observed in the transient state, following addition of either substrate, is accompanied by internalization of 2 mol of calcium per mole of phosphoenzyme. The internalized calcium is then translocated with a sequential pattern, independent of the substrate used. Following a rate-limiting step, the phosphoenzyme undergoes hydrolytic cleavage and proceeds to the steady-state activity which is soon back inhibited by the rise of Ca 2+ concentration in the lumen of the vesicles. When the back inhibition is released by the addition of oxalate, substrate utilization and calcium transport occur with a ratio of 1:2, independent of the substrate and its concentration. When the nucleotide binding site is derivatized with FITP, the enzyme can still utilize acetyl phosphate (but not ATP) for calcium transport. These observations demonstrate that the basic coupling mechanism of catalysis and calcium transport involves the phosphorylation and calcium binding domains, and not the nucleotide binding domain. On the other hand, occupancy of the FITC-sensitive nucleotide site is involved in kinetic regulation not only with respect to utilization of substrate for the phosphoryl transfer reaction but also for subsequent steps related to calcium translocation and phosphoenzyme turnover

  5. Single nucleotide resolution RNA-seq uncovers new regulatory mechanisms in the opportunistic pathogen Streptococcus agalactiae.

    Science.gov (United States)

    Rosinski-Chupin, Isabelle; Sauvage, Elisabeth; Sismeiro, Odile; Villain, Adrien; Da Cunha, Violette; Caliot, Marie-Elise; Dillies, Marie-Agnès; Trieu-Cuot, Patrick; Bouloc, Philippe; Lartigue, Marie-Frédérique; Glaser, Philippe

    2015-05-30

    Streptococcus agalactiae, or Group B Streptococcus, is a leading cause of neonatal infections and an increasing cause of infections in adults with underlying diseases. In an effort to reconstruct the transcriptional networks involved in S. agalactiae physiology and pathogenesis, we performed an extensive and robust characterization of its transcriptome through a combination of differential RNA-sequencing in eight different growth conditions or genetic backgrounds and strand-specific RNA-sequencing. Our study identified 1,210 transcription start sites (TSSs) and 655 transcript ends as well as 39 riboswitches and cis-regulatory regions, 39 cis-antisense non-coding RNAs and 47 small RNAs potentially acting in trans. Among these putative regulatory RNAs, ten were differentially expressed in response to an acid stress and two riboswitches sensed directly or indirectly the pH modification. Strikingly, 15% of the TSSs identified were associated with the incorporation of pseudo-templated nucleotides, showing that reiterative transcription is a pervasive process in S. agalactiae. In particular, 40% of the TSSs upstream genes involved in nucleotide metabolism show reiterative transcription potentially regulating gene expression, as exemplified for pyrG and thyA encoding the CTP synthase and the thymidylate synthase respectively. This comprehensive map of the transcriptome at the single nucleotide resolution led to the discovery of new regulatory mechanisms in S. agalactiae. It also provides the basis for in depth analyses of transcriptional networks in S. agalactiae and of the regulatory role of reiterative transcription following variations of intra-cellular nucleotide pools.

  6. Extracellular Purine Metabolism Is the Switchboard of Immunosuppressive Macrophages and a Novel Target to Treat Diseases With Macrophage Imbalances

    Directory of Open Access Journals (Sweden)

    Anna Ohradanova-Repic

    2018-04-01

    Full Text Available If misregulated, macrophage (Mϕ–T cell interactions can drive chronic inflammation thereby causing diseases, such as rheumatoid arthritis (RA. We report that in a proinflammatory environment, granulocyte-Mϕ (GM-CSF- and Mϕ colony-stimulating factor (M-CSF-dependent Mϕs have dichotomous effects on T cell activity. While GM-CSF-dependent Mϕs show a highly stimulatory activity typical for M1 Mϕs, M-CSF-dependent Mϕs, marked by folate receptor β (FRβ, adopt an immunosuppressive M2 phenotype. We find the latter to be caused by the purinergic pathway that directs release of extracellular ATP and its conversion to immunosuppressive adenosine by co-expressed CD39 and CD73. Since we observed a misbalance between immunosuppressive and immunostimulatory Mϕs in human and murine arthritic joints, we devised a new strategy for RA treatment based on targeted delivery of a novel methotrexate (MTX formulation to the immunosuppressive FRβ+CD39+CD73+ Mϕs, which boosts adenosine production and curtails the dominance of proinflammatory Mϕs. In contrast to untargeted MTX, this approach leads to potent alleviation of inflammation in the murine arthritis model. In conclusion, we define the Mϕ extracellular purine metabolism as a novel checkpoint in Mϕ cell fate decision-making and an attractive target to control pathological Mϕs in immune-mediated diseases.

  7. Purine Nucleoside Phosphorylase (PNP) Activity of Lymphocytes and T Cell Subsets in Peripheral Blood in Thyroid Tumors

    International Nuclear Information System (INIS)

    Kim, Dong Soo

    1992-01-01

    To elucidate alteration of purine nucleoside phosphorylase (PNP) activity of peripheral lymphocytes and helper/inducer and suppressor/cytototxic T cells in patients with thyroid tumors, the author examined PNP activity, and CD4 + and CD8 + cells of peripheral blood in 20 cases of simple goiter, 9 cases of thyroid adenoma and 20 cases of thyroid cancer as well as 11 cases of adult healthy subjects as control. Diagnoses were established on the basis of commonly accepted clinical and biochemical criteria in simple goiter and were confirmed histopathologically in thyroid adenoma and cancer. All blood was obtained from veins of the patients and control subjects in Pusan National University Hospital during the period of January to August, 1991. The results obtained were summarized as follows: 1) The PNP activity was significantly decreased or tended to be decreased in thyroid adenomas and cancers as compared with control subjects and simple goiters. 2) The percentage of CD8 cells was significantly decreased or tended to be decreased in thyroid cancers as compared with simple goiters, thyroid adenomas and control subjects. 3) The CD4/CD8 ratio was significantly increased or tended to be increased in thyroid cancer as compared with simple goiters, thyroid adenomas and control subjects. On the basis of the results, it can be suggested that the immunodysfunction in thyroid cancer may be due to decreased suppressor/cytotoxic T cells, and the estimation of PNP activity of peripheral lymphocyte is a helpful test in detecting the immune status in thyroid tumors.

  8. Site-Selective Ribosylation of Fluorescent Nucleobase Analogs Using Purine-Nucleoside Phosphorylase as a Catalyst: Effects of Point Mutations

    Directory of Open Access Journals (Sweden)

    Alicja Stachelska-Wierzchowska

    2015-12-01

    Full Text Available Enzymatic ribosylation of fluorescent 8-azapurine derivatives, like 8-azaguanine and 2,6-diamino-8-azapurine, with purine-nucleoside phosphorylase (PNP as a catalyst, leads to N9, N8, and N7-ribosides. The final proportion of the products may be modulated by point mutations in the enzyme active site. As an example, ribosylation of the latter substrate by wild-type calf PNP gives N7- and N8-ribosides, while the N243D mutant directs the ribosyl substitution at N9- and N7-positions. The same mutant allows synthesis of the fluorescent N7-β-d-ribosyl-8-azaguanine. The mutated form of the E. coli PNP, D204N, can be utilized to obtain non-typical ribosides of 8-azaadenine and 2,6-diamino-8-azapurine as well. The N7- and N8-ribosides of the 8-azapurines can be analytically useful, as illustrated by N7-β-d-ribosyl-2,6-diamino-8-azapurine, which is a good fluorogenic substrate for mammalian forms of PNP, including human blood PNP, while the N8-riboside is selective to the E. coli enzyme.

  9. Enzymatic Synthesis of Highly Fluorescent 8-Azapurine Ribosides Using a Purine Nucleoside Phosphorylase Reverse Reaction: Variable Ribosylation Sites

    Directory of Open Access Journals (Sweden)

    Goran Mikleušević

    2013-10-01

    Full Text Available Various forms of purine-nucleoside phosphorylase (PNP were used as catalysts of enzymatic ribosylation of selected fluorescent 8-azapurines. It was found that the recombinant calf PNP catalyzes ribosylation of 2,6-diamino-8-azapurine in a phosphate-free medium, with ribose-1-phosphate as ribose donor, but the ribosylation site is predominantly N7 and N8, with the proportion of N8/N7 ribosylated products markedly dependent on the reaction conditions. Both products are fluorescent. Application of the E. coli PNP gave a mixture of N8 and N9-substituted ribosides. Fluorescence of the ribosylated 2,6-diamino-8-azapurine has been briefly characterized. The highest quantum yield, ~0.9, was obtained for N9-β-d-riboside (λmax 365 nm, while for N8-β-d-riboside, emitting at ~430 nm, the fluorescence quantum yield was found to be close to 0.4. Ribosylation of 8-azaguanine with calf PNP as a catalyst goes exclusively to N9. By contrast, the E. coli PNP ribosylates 8-azaGua predominantly at N9, with minor, but highly fluorescent products ribosylated at N8/N7.

  10. Role of Achiral Nucleobases in Multicomponent Chiral Self-Assembly: Purine-Triggered Helix and Chirality Transfer.

    Science.gov (United States)

    Deng, Ming; Zhang, Li; Jiang, Yuqian; Liu, Minghua

    2016-11-21

    Chiral self-assembly is a basic process in biological systems, where many chiral biomolecules such as amino acids and sugars play important roles. Achiral nucleobases usually covalently bond to saccharides and play a significant role in the formation of the double helix structure. However, it remains unclear how the achiral nucleobases can function in chiral self-assembly without the sugar modification. Herein, we have clarified that purine nucleobases could trigger N-(9-fluorenylmethox-ycarbonyl) (Fmoc)-protected glutamic acid to self-assemble into helical nanostructures. Moreover, the helical nanostructure could serve as a matrix and transfer the chirality to an achiral fluorescence probe, thioflavin T (ThT). Upon chirality transfer, the ThT showed not only supramolecular chirality but also circular polarized fluorescence (CPL). Without the nucleobase, the self-assembly processes cannot happen, thus providing an example where achiral molecules played an essential role in the expression and transfer of the chirality. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. One-step enzymatic synthesis of nucleosides from low water-soluble purine bases in non-conventional media.

    Science.gov (United States)

    Fernández-Lucas, Jesús; Fresco-Taboada, Alba; de la Mata, Isabel; Arroyo, Miguel

    2012-07-01

    The effect of several water-miscible cosolvents on activity and stability of soluble and immobilized 2'-deoxyribosyltransferase from Lactobacillus reuteri on Sepabeads® has been studied in order to establish optimal conditions for enzymatic synthesis of nucleosides using purine bases with low solubility in aqueous buffer. As a rule of thumb, there was a general reduction of soluble enzyme activity when cosolvent content was gradually increased in reaction medium. In contrast, immobilized enzyme activity was enhanced 1.2-1.4-fold at 20% of methanol, ethanol, 2-propanol, diethylene glycol, and acetone; and at 10% and 30% acetonitrile. Likewise, highest increased activity (1.8-fold) was also obtained in presence of 20% acetonitrile. Immobilized enzyme was successfully used in the synthesis of 2'-deoxyxanthosine and 2'-deoxyguanosine using 2'-deoxyuridine as sugar donor and the corresponding poor water-soluble base in the presence of 30% of methanol, ethanol, 2-propanol, ethylene glycol, acetonitrile, and DMSO, giving high nucleoside yields at 4h. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Correlation of nucleotides and carbohydrates metabolism with pro-oxidant and antioxidant systems of erythrocytes depending on age in patients with colorectal cancer.

    Science.gov (United States)

    Zuikov, S A; Borzenko, B G; Shatova, O P; Bakurova, E M; Polunin, G E

    2014-06-01

    To examine the relationship between metabolic features of purine nucleotides and antioxidant system depending on the age of patients with colorectal cancer. The activity of adenosine deaminase, xanthine oxidase, glutathione peroxidase, superoxide dismutase and glucose-6-phosphate dehydrogenase, the NOx concentration and the oxidative modification of proteins were determined spectrophotometricaly in 50 apparently healthy people and 26 patients with colorectal cancer stage -III---IV, aged 40 to 79 years. Increase of pro-oxidant system of erythrocytes with the age against decrease in level of antioxidant protection in both healthy individuals and colorectal cancer patients was determined. A significant increase of pro-ducts of oxidative proteins modification in erythrocytes with ageing was shown. Statistically significant correlation between enzymatic and non enzymatic markers pro-oxidant system and the activity of antioxidant defense enzymes in erythrocytes of patient with colorectal cancer was determined. Obtained results have demonstrated the imbalance in the antioxidant system of erythrocytes in colorectal cancer patients that improve the survival of cancer cells that is more distinctly manifested in ageing.

  13. Long Term Expression of Drosophila melanogaster Nucleoside Kinase in Thymidine Kinase 2-deficient Mice with No Lethal Effects Caused by Nucleotide Pool Imbalances*

    Science.gov (United States)

    Krishnan, Shuba; Paredes, João A.; Zhou, Xiaoshan; Kuiper, Raoul V.; Hultenby, Kjell; Curbo, Sophie; Karlsson, Anna

    2014-01-01

    Mitochondrial DNA depletion caused by thymidine kinase 2 (TK2) deficiency can be compensated by a nucleoside kinase from Drosophila melanogaster (Dm-dNK) in mice. We show that transgene expression of Dm-dNK in Tk2 knock-out (Tk2−/−) mice extended the life span of Tk2−/− mice from 3 weeks to at least 20 months. The Dm-dNK+/−Tk2−/− mice maintained normal mitochondrial DNA levels throughout the observation time. A significant difference in total body weight due to the reduction of subcutaneous and visceral fat in the Dm-dNK+/−Tk2−/− mice was the only visible difference compared with control mice. This indicates an effect on fat metabolism mediated through residual Tk2 deficiency because Dm-dNK expression was low in both liver and fat tissues. Dm-dNK expression led to increased dNTP pools and an increase in the catabolism of purine and pyrimidine nucleotides but these alterations did not apparently affect the mice during the 20 months of observation. In conclusion, Dm-dNK expression in the cell nucleus expanded the total dNTP pools to levels required for efficient mitochondrial DNA synthesis, thereby compensated the Tk2 deficiency, during a normal life span of the mice. The Dm-dNK+/− mouse serves as a model for nucleoside gene or enzyme substitutions, nucleotide imbalances, and dNTP alterations in different tissues. PMID:25296759

  14. The pyrimidine nucleotide carrier PNC1 and mitochondrial trafficking of thymidine phosphates in cultured human cells

    Energy Technology Data Exchange (ETDEWEB)

    Franzolin, Elisa; Miazzi, Cristina; Frangini, Miriam; Palumbo, Elisa; Rampazzo, Chiara [Department of Biology, University of Padova, Via Ugo Bassi 58B, I-35131 Padova (Italy); Bianchi, Vera, E-mail: vbianchi@bio.unipd.it [Department of Biology, University of Padova, Via Ugo Bassi 58B, I-35131 Padova (Italy)

    2012-10-15

    In cycling cells cytosolic de novo synthesis of deoxynucleotides is the main source of precursors for mitochondrial (mt) DNA synthesis. The transfer of deoxynucleotides across the inner mt membrane requires protein carriers. PNC1, a SLC25 family member, exchanges pyrimidine nucleoside triphosphates in liposomes and its downregulation decreases mtUTP concentration in cultured cells. By an isotope-flow protocol we confirmed transport of uridine nucleotides by PNC1 in intact cultured cells and investigated PNC1 involvement in the mt trafficking of thymidine phosphates. Key features of our approach were the manipulation of PNC1 expression by RNA interference or inducible overexpression, the employment of cells proficient or deficient for cytosolic thymidine kinase (TK1) to distinguish the direction of flow of thymidine nucleotides across the mt membrane during short pulses with [{sup 3}H]-thymidine, the determination of mtdTTP specific radioactivity to quantitate the rate of mtdTTP export to the cytoplasm. Downregulation of PNC1 in TK1{sup -} cells increased labeled dTTP in mitochondria due to a reduced rate of export. Overexpression of PNC1 in TK1{sup +} cells increased mtdTTP pool size and radioactivity, suggesting an involvement in the import of thymidine phosphates. Thus PNC1 is a component of the network regulating the mtdTTP pool in human cells. -- Highlights: Black-Right-Pointing-Pointer Thymidine phosphates exchange between mitochondria and cytosol in mammalian cells. Black-Right-Pointing-Pointer siRNA-downregulation of PNC1 delays mitochondrial dTTP export in TK1{sup -} cells. Black-Right-Pointing-Pointer PNC1 overexpression accumulates dTTP in mitochondria of TK1{sup +} cells. Black-Right-Pointing-Pointer PNC1 exchanges thymidine nucleotides across the mitochondrial inner membrane. Black-Right-Pointing-Pointer PNC1 participates in the regulation of the mtdTTP pool supporting mtDNA synthesis.

  15. The pyrimidine nucleotide carrier PNC1 and mitochondrial trafficking of thymidine phosphates in cultured human cells

    International Nuclear Information System (INIS)

    Franzolin, Elisa; Miazzi, Cristina; Frangini, Miriam; Palumbo, Elisa; Rampazzo, Chiara; Bianchi, Vera

    2012-01-01

    In cycling cells cytosolic de novo synthesis of deoxynucleotides is the main source of precursors for mitochondrial (mt) DNA synthesis. The transfer of deoxynucleotides across the inner mt membrane requires protein carriers. PNC1, a SLC25 family member, exchanges pyrimidine nucleoside triphosphates in liposomes and its downregulation decreases mtUTP concentration in cultured cells. By an isotope-flow protocol we confirmed transport of uridine nucleotides by PNC1 in intact cultured cells and investigated PNC1 involvement in the mt trafficking of thymidine phosphates. Key features of our approach were the manipulation of PNC1 expression by RNA interference or inducible overexpression, the employment of cells proficient or deficient for cytosolic thymidine kinase (TK1) to distinguish the direction of flow of thymidine nucleotides across the mt membrane during short pulses with [ 3 H]-thymidine, the determination of mtdTTP specific radioactivity to quantitate the rate of mtdTTP export to the cytoplasm. Downregulation of PNC1 in TK1 − cells increased labeled dTTP in mitochondria due to a reduced rate of export. Overexpression of PNC1 in TK1 + cells increased mtdTTP pool size and radioactivity, suggesting an involvement in the import of thymidine phosphates. Thus PNC1 is a component of the network regulating the mtdTTP pool in human cells. -- Highlights: ► Thymidine phosphates exchange between mitochondria and cytosol in mammalian cells. ► siRNA-downregulation of PNC1 delays mitochondrial dTTP export in TK1 − cells. ► PNC1 overexpression accumulates dTTP in mitochondria of TK1 + cells. ► PNC1 exchanges thymidine nucleotides across the mitochondrial inner membrane. ► PNC1 participates in the regulation of the mtdTTP pool supporting mtDNA synthesis.

  16. Role of guanosine kinase in the utilization of guanosine for nucleotide synthesis in Escherichia coli

    DEFF Research Database (Denmark)

    Hove-Jensen, Bjarne; Nygaard, Per

    1989-01-01

    Using purine auxotrophic strains of Escherichia coli with additional genetic lesions in the pathways of interconversion and salvage of purine compounds, we demonstrated the in vivo function of guanosine kinase and inosine kinase. Mutants with increased ability to utilize guanosine were isolated b...... a purF, a purL or a purM mutation. A revised map location of the gsk gene is presented and the gene order established as proC-acrA-apt-adk-gsk-purE....

  17. Nucleotide sequence of Hungarian grapevine chrome mosaic nepovirus RNA1.

    Science.gov (United States)

    Le Gall, O; Candresse, T; Brault, V; Dunez, J

    1989-10-11

    The nucleotide sequence of the RNA1 of hungarian grapevine chrome mosaic virus, a nepovirus very closely related to tomato black ring virus, has been determined from cDNA clones. It is 7212 nucleotides in length excluding the 3' terminal poly(A) tail and contains a large open reading frame extending from nucleotides 216 to 6971. The presumably encoded polyprotein is 2252 amino acids in length with a molecular weight of 250 kDa. The primary structure of the polyprotein was compared with that of other viral polyproteins, revealing the same general genetic organization as that of other picorna-like viruses (comoviruses, potyviruses and picornaviruses), except that an additional protein is suspected to occupy the N-terminus of the polyprotein.

  18. DNA Nucleotide Sequence Restricted by the RI Endonuclease

    Science.gov (United States)

    Hedgpeth, Joe; Goodman, Howard M.; Boyer, Herbert W.

    1972-01-01

    The sequence of DNA base pairs adjacent to the phosphodiester bonds cleaved by the RI restriction endonuclease in unmodified DNA from coliphage λ has been determined. The 5′-terminal nucleotide labeled with 32P and oligonucleotides up to the heptamer were analyzed from a pancreatic DNase digest. The following sequence of nucleotides adjacent to the RI break made in λ DNA was deduced from these data and from the 3′-dinucleotide sequence and nearest-neighbor analysis obtained from repair synthesis with the DNA polymerase of Rous sarcoma virus [Formula: see text] The RI endonuclease cleavage of the phosphodiester bonds (indicated by arrows) generates 5′-phosphoryls and short cohesive termini of four nucleotides, pApApTpT. The most striking feature of the sequence is its symmetry. PMID:4343974

  19. Norbornane-based nucleoside and nucleotide analogues locked in North conformation

    Czech Academy of Sciences Publication Activity Database

    Dejmek, Milan; Šála, Michal; Hřebabecký, Hubert; Dračínský, Martin; Procházková, Eliška; Chalupská, Dominika; Klíma, Martin; Plačková, Pavla; Hájek, Miroslav; Andrei, G.; Naesens, L.; Leyssen, P.; Neyts, J.; Balzarini, J.; Bouřa, Evžen; Nencka, Radim

    2015-01-01

    Roč. 23, č. 1 (2015), s. 184-191 ISSN 0968-0896 R&D Projects: GA ČR GPP207/12/P625; GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : carbocyclic nucleosides * purines * norbornane * antiviral * PI4KIIalpha Subject RIV: CC - Organic Chemistry Impact factor: 2.923, year: 2015

  20. Effects of luminal flow and nucleotides on [Ca(2+)](i) in rabbit cortical collecting duct.

    Science.gov (United States)

    Woda, Craig B; Leite, Maurilo; Rohatgi, Rajeev; Satlin, Lisa M

    2002-09-01

    Nucleotide binding to purinergic P2 receptors contributes to the regulation of a variety of physiological functions in renal epithelial cells. Whereas P2 receptors have been functionally identified at the basolateral membrane of the cortical collecting duct (CCD), a final regulatory site of urinary Na(+), K(+), and acid-base excretion, controversy exists as to whether apical purinoceptors exist in this segment. Nor has the distribution of receptor subtypes present on the unique cell populations that constitute Ca(2+) the CCD been established. To examine this, we measured nucleotide-induced changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) in fura 2-loaded rabbit CCDs microperfused in vitro. Resting [Ca(2+)](i) did not differ between principal and intercalated cells, averaging approximately 120 nM. An acute increase in tubular fluid flow rate, associated with a 20% increase in tubular diameter, led to increases in [Ca(2+)](i) in both cell types. Luminal perfusion of 100 microM UTP or ATP-gamma-S, in the absence of change in flow rate, caused a rapid and transient approximately fourfold increase in [Ca(2+)](i) in both cell types (P < 0.05). Luminal suramin, a nonspecific P2 receptor antagonist, blocked the nucleotide- but not flow-induced [Ca(2+)](i) transients. Luminal perfusion with a P2X (alpha,beta-methylene-ATP), P2X(7) (benzoyl-benzoyl-ATP), P2Y(1) (2-methylthio-ATP), or P2Y(4)/P2Y(6) (UDP) receptor agonist had no effect on [Ca(2+)](i). The nucleotide-induced [Ca(2+)](i) transients were inhibited by the inositol-1,4,5-triphosphate receptor blocker 2-aminoethoxydiphenyl borate, thapsigargin, which depletes internal Ca(2+) stores, luminal perfusion with a Ca(2+)-free perfusate, or the L-type Ca(2+) channel blocker nifedipine. These results suggest that luminal nucleotides activate apical P2Y(2) receptors in the CCD via pathways that require both internal Ca(2+) mobilization and extracellular Ca(2+) entry. The flow-induced rise in [Ca(2+)](i) is

  1. Insights into phosphate cooperativity and influence of substrate modifications on binding and catalysis of hexameric purine nucleoside phosphorylases.

    Directory of Open Access Journals (Sweden)

    Priscila O de Giuseppe

    Full Text Available The hexameric purine nucleoside phosphorylase from Bacillus subtilis (BsPNP233 displays great potential to produce nucleoside analogues in industry and can be exploited in the development of new anti-tumor gene therapies. In order to provide structural basis for enzyme and substrates rational optimization, aiming at those applications, the present work shows a thorough and detailed structural description of the binding mode of substrates and nucleoside analogues to the active site of the hexameric BsPNP233. Here we report the crystal structure of BsPNP233 in the apo form and in complex with 11 ligands, including clinically relevant compounds. The crystal structure of six ligands (adenine, 2'deoxyguanosine, aciclovir, ganciclovir, 8-bromoguanosine, 6-chloroguanosine in complex with a hexameric PNP are presented for the first time. Our data showed that free bases adopt alternative conformations in the BsPNP233 active site and indicated that binding of the co-substrate (2'deoxyribose 1-phosphate might contribute for stabilizing the bases in a favorable orientation for catalysis. The BsPNP233-adenosine complex revealed that a hydrogen bond between the 5' hydroxyl group of adenosine and Arg(43* side chain contributes for the ribosyl radical to adopt an unusual C3'-endo conformation. The structures with 6-chloroguanosine and 8-bromoguanosine pointed out that the Cl(6 and Br(8 substrate modifications seem to be detrimental for catalysis and can be explored in the design of inhibitors for hexameric PNPs from pathogens. Our data also corroborated the competitive inhibition mechanism of hexameric PNPs by tubercidin and suggested that the acyclic nucleoside ganciclovir is a better inhibitor for hexameric PNPs than aciclovir. Furthermore, comparative structural analyses indicated that the replacement of Ser(90 by a threonine in the B. cereus hexameric adenosine phosphorylase (Thr(91 is responsible for the lack of negative cooperativity of phosphate binding

  2. Diagnosis of immunodeficiency caused by a purine nucleoside phosphorylase defect by using tandem mass spectrometry on dried blood spots.

    Science.gov (United States)

    la Marca, Giancarlo; Canessa, Clementina; Giocaliere, Elisa; Romano, Francesca; Malvagia, Sabrina; Funghini, Silvia; Moriondo, Maria; Valleriani, Claudia; Lippi, Francesca; Ombrone, Daniela; Della Bona, Maria Luisa; Speckmann, Carsten; Borte, Stephan; Brodszki, Nicholas; Gennery, Andrew R; Weinacht, Katja; Celmeli, Fatih; Pagel, Julia; de Martino, Maurizio; Guerrini, Renzo; Wittkowski, Helmut; Santisteban, Ines; Bali, Pawan; Ikinciogullari, Aydan; Hershfield, Michael; Notarangelo, Luigi D; Resti, Massimo; Azzari, Chiara

    2014-07-01

    Purine nucleoside phosphorylase (PNP) deficiency is a rare form of autosomal recessive combined primary immunodeficiency caused by a enzyme defect leading to the accumulation of inosine, 2'-deoxy-inosine (dIno), guanosine, and 2'-deoxy-guanosine (dGuo) in all cells, especially lymphocytes. Treatments are available and curative for PNP deficiency, but their efficacy depends on the early approach. PNP-combined immunodeficiency complies with the criteria for inclusion in a newborn screening program. This study evaluate whether mass spectrometry can identify metabolite abnormalities in dried blood spots (DBSs) from affected patients, with the final goal of individuating the disease at birth during routine newborn screening. DBS samples from 9 patients with genetically confirmed PNP-combined immunodeficiency, 10,000 DBS samples from healthy newborns, and 240 DBSs from healthy donors of different age ranges were examined. Inosine, dIno, guanosine, and dGuo were tested by using tandem mass spectrometry (TMS). T-cell receptor excision circle (TREC) and kappa-deleting recombination excision circle (KREC) levels were evaluated by using quantitative RT-PCR only for the 2 patients (patients 8 and 9) whose neonatal DBSs were available. Mean levels of guanosine, inosine, dGuo, and dIno were 4.4, 133.3, 3.6, and 3.8 μmol/L, respectively, in affected patients. No indeterminate or false-positive results were found. In patient 8 TREC levels were borderline and KREC levels were abnormal; in patient 9 TRECs were undetectable, whereas KREC levels were normal. TMS is a valid method for diagnosis of PNP deficiency on DBSs of affected patients at a negligible cost. TMS identifies newborns with PNP deficiency, whereas TREC or KREC measurement alone can fail. Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

  3. Ion Transport in Human Pancreatic Duct Epithelium, Capan-1 Cells, Is Regulated by Secretin, VIP, Acetylcholine, and Purinergic Receptors

    DEFF Research Database (Denmark)

    Wang, Jing; Novak, Ivana

    2013-01-01

    OBJECTIVES: The objective of the study was to establish a solid model of polarized epithelium for human pancreatic ducts, where electrical parameters could be measured as indicators of ion transport. Further, we aimed to determine functional expression of several receptors, in particular, puriner...... transport in human pancreatic duct epithelium, Capan-1 cells, is regulated by secretin, VIP, acetylcholine, adenosine, and purinergic P2 receptors; and this human model has a good potential for studies of physiology and pathophysiology of pancreatic duct ion transport....

  4. E2F1 and p53 Transcription Factors as Accessory Factors for Nucleotide Excision Repair

    Directory of Open Access Journals (Sweden)

    David G. Johnson

    2012-10-01

    Full Text Available Many of the biochemical details of nucleotide excision repair (NER have been established using purified proteins and DNA substrates. In cells however, DNA is tightly packaged around histones and other chromatin-associated proteins, which can be an obstacle to efficient repair. Several cooperating mechanisms enhance the efficiency of NER by altering chromatin structure. Interestingly, many of the players involved in modifying chromatin at sites of DNA damage were originally identified as regulators of transcription. These include ATP-dependent chromatin remodelers, histone modifying enzymes and several transcription factors. The p53 and E2F1 transcription factors are well known for their abilities to regulate gene expression in response to DNA damage. This review will highlight the underappreciated, transcription-independent functions of p53 and E2F1 in modifying chromatin structure in response to DNA damage to promote global NER.

  5. Effects of chicory inulin on serum metabolites of uric acid, lipids, glucose, and abdominal fat deposition in quails induced by purine-rich diets.

    Science.gov (United States)

    Lin, Zhijian; Zhang, Bing; Liu, Xiaoqing; Jin, Rui; Zhu, Wenjing

    2014-11-01

    Inulin, a group of dietary fibers, is reported to improve the metabolic disorders. In the present study, we investigated the effects of chicory inulin on serum metabolites of uric acid (UA), lipids, glucose, and abdominal fat deposition in quail model induced by a purine-rich diet. In this study, 60 male French quails were randomly allocated to five groups: CON (control group), MOD (model group), BEN (benzbromarone-treated group), CHI-H (high-dosage chicory inulin-treated group), and CHI-L (low-dosage chicory inulin-treated group). The serum UA level was significantly increased in the model group from days 7 to 28, as well as triglyceride (TG) and free fatty acid (FFA) increased later in the experimental period. The abdominal fat ratio was increased on day 28. Benzbromarone can decrease UA levels on days 14 and 28. The high and low dosage of chicory inulin also decreased serum UA levels on days 7, 14, and 28. The abdominal fat ratio, activity, and protein of acetyl-CoA carboxylase (ACC) were decreased in chicory inulin-treated groups. The activities of xanthine oxidase (XOD) and fatty acid synthase (FAS) were increased in the model group and decreased in the benzbromarone and chicory inulin groups. This study evaluated a quail model of induced hyperuricemia with other metabolic disorders caused by a high-purine diet. The results indicated that a purine-rich diet might contribute to the development of hyperuricemia, hypertriglyceridemia, and abdominal obesity. Chicory inulin decreased serum UA, TG, and abdominal fat deposition in a quail model of hyperuricemia by altering the ACC protein expression and FAS and XOD activities.

  6. Structural Analysis of DFG-in and DFG-out Dual Src-Abl Inhibitors Sharing a Common Vinyl Purine Template

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Tianjun; Commodore, Lois; Huang, Wei-Sheng; Wang, Yihan; Sawyer, Tomi K.; Shakespeare, William C.; Clackson, Tim; Zhu, Xiaotian; Dalgarno, David C. (ARIAD)

    2010-09-30

    Bcr-Abl is the oncogenic protein tyrosine kinase responsible for chronic myeloid leukemia (CML). Treatment of the disease with imatinib (Gleevec) often results in drug resistance via kinase mutations at the advanced phases of the disease, which has necessitated the development of new mutation-resistant inhibitors, notably against the T315I gatekeeper mutation. As part of our efforts to discover such mutation resistant Abl inhibitors, we have focused on optimizing purine template kinase inhibitors, leading to the discovery of potent DFG-in and DFG-out series of Abl inhibitors that are also potent Src inhibitors. Here we present crystal structures of Abl bound by two such inhibitors, based on a common N9-arenyl purine, and that represent both DFG-in and -out binding modes. In each structure the purine template is bound deeply in the adenine pocket and the novel vinyl linker forms a non-classical hydrogen bond to the gatekeeper residue, Thr315. Specific template substitutions promote either a DFG-in or -out binding mode, with the kinase binding site adjusting to optimize molecular recognition. Bcr-Abl T315I mutant kinase is resistant to all currently marketed Abl inhibitors, and is the focus of intense drug discovery efforts. Notably, our DFG-out inhibitor, AP24163, exhibits modest activity against this mutant, illustrating that this kinase mutant can be inhibited by DFG-out class inhibitors. Furthermore our DFG-out inhibitor exhibits dual Src-Abl activity, absent from the prototypical DFG-out inhibitor, imatinib as well as its analog, nilotinib. The data presented here provides structural guidance for the further design of novel potent DFG-out class inhibitors against Src, Abl and Abl T315I mutant kinases.

  7. Screening and characterization of purine nucleoside degrading lactic acid bacteria isolated from Chinese sauerkraut and evaluation of the serum uric acid lowering effect in hyperuricemic rats.

    Directory of Open Access Journals (Sweden)

    Ming Li

    Full Text Available Hyperuricemia is well known as the cause of gout. In recent years, it has also been recognized as a risk factor for arteriosclerosis, cerebrovascular and cardiovascular diseases, and nephropathy in diabetic patients. Foods high in purine compounds are more potent in exacerbating hyperuricemia. Therefore, the development of probiotics that efficiently degrade purine compounds is a promising potential therapy for the prevention of hyperuricemia. In this study, fifty-five lactic acid bacteria isolated from Chinese sauerkraut were evaluated for the ability to degrade inosine and guanosine, the two key intermediates in purine metabolism. After a preliminary screening based on HPLC, three candidate strains with the highest nucleoside degrading rates were selected for further characterization. The tested biological characteristics of candidate strains included acid tolerance, bile tolerance, anti-pathogenic bacteria activity, cell adhesion ability, resistance to antibiotics and the ability to produce hydrogen peroxide. Among the selected strains, DM9218 showed the best probiotic potential compared with other strains despite its poor bile resistance. Analysis of 16S rRNA sequences showed that DM9218 has the highest similarity (99% to Lactobacillus plantarum WCFS1. The acclimated strain DM9218-A showed better resistance to 0.3% bile salt, and its survival in gastrointestinal tract of rats was proven by PCR-DGGE. Furthermore, the effects of DM9218-A in a hyperuricemia rat model were evaluated. The level of serum uric acid in hyperuricemic rat can be efficiently reduced by the intragastric administration of DM9218-A (P<0.05. The preventive treatment of DM9218-A caused a greater reduction in serum uric acid concentration in hyperuricemic rats than the later treatment (P<0.05. Our results suggest that DM9218-A may be a promising candidate as an adjunctive treatment in patients with hyperuricemia during the onset period of disease. DM9218-A also has potential

  8. Urinary excretion of purine derivatives as an index of microbial protein supply in cross-bred (Bos indicus x Bos taurus) cattle in tropical environment

    International Nuclear Information System (INIS)

    Ojeda, A.; Parra, O.

    1999-01-01

    Four experiments were carried out to establish a response model between urinary excretion of purine derivatives (PD) and microbial production in Bos indicus x Bos taurus cross-bred cattle: LZ, MZ and HZ (3/8, 1/2 and 5/8 Bos indicus, respectively). The fasting PD excretion was considered as endogenous excretion and amounted to 268 (± 85.1), 294 (± 128.1) and 269 (± 68.4) μmol/kg W 0.75 for LZ, MZ and HZ, respectively. Urinary recovery of absorbed purine bases (PB) was calculated as the urinary recovery of a single dose of intrajugular infused uric acid (1,3- 15 N). In HZ crossbred cattle 83% (± 20.3) of infused uric acid was recovered in the urinary PD. The relationship between duodenal purine absorption (X, mmol/d) and urinary PD excretion (Y, mmol/d) was defined in HZ crossbred cattle as Y = 0.83 X + 0.269W 0.75 (± 85.1), assuming that the endogenous contribution was constant and independent of the exogenous PB supply. The activity of xanthine oxidase (EC 1.2.3.2.) was determined in HZ and MZ and was found to be higher in the liver (0.62 and 0.66 units/g, respectively) than in intestinal mucosa (0.09 and 0.03 units/g, respectively), whereas xanthine oxidase activity was practically absent in plasma of both cross breeds. The ratio PB:total N was determined in microbial extracts taken from rumen fluid of cows fed Bermuda grass (Cynodon dactylon) as the sole diet or supplemented (ratio of 80:20, grass: supplement) with gluten feed, soybean hulls or Gliricidia species and were found to range from 1.52-1.62 μmol PB/mg N. (author)

  9. Synthesis, Acidity Constants and Tautomeric Structure of the Diazonium Coupling Products of 2-(Benzylsulfanyl-7H-purin-6-one in Its Ground and Excited States

    Directory of Open Access Journals (Sweden)

    Hosam A. Saad

    2011-10-01

    Full Text Available A series of new 8-arylhydrazono-2-(benzylsulfanyl-7H-purin-6-ones 6 were synthesized, their electronic absorption spectra in different organic solvents of varying polarities were investigated and their acid dissociation constants in both the ground and excited states were determined spectrophotometrically. The tautomeric structures of such products were elucidated by spectral analyses and correlation of their acid dissociation constants with the Hammett equation. The results indicated that the studied compounds 6 exist predominantly in the hydrazone tautomeric form 6A in both the ground and excited states.

  10. Simultaneous quantification of purine and pyrimidine bases, nucleosides and their degradation products in bovine blood plasma by high performance liquid chromatography tandem mass spectrometry

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Stentoft; Vestergaard, Mogens; Løvendahl, Peter

    2014-01-01

    describes the development and validation of a sensitive and specific method for simultaneous determination of 20 purines (adenine, guanine, guanosine, inosine, 2′-deoxyguanosine, 2′-deoxyinosine, xanthine, hypoxanthine), pyrimidines (cytosine, thymine, uracil, cytidine, uridine, thymidine, 2′-deoxyuridine...... investigated. It was confirmed that using a log-calibration model rather than a linear calibration model resulted in lower CV% and a lack of fit test demonstrated a satisfying linear regression. The method covers concentration ranges for each metabolite according to that in actual samples, e.g. guanine: 0...... veins and, with a few exceptions, also for other species such as chicken, pig, mink, human and rat....

  11. Development of a single nucleotide polymorphism (SNP) marker for ...

    African Journals Online (AJOL)

    The nature of the single nucleotide polymorphism (SNP) marker was validated by DNA sequencing of the parental PCR products. Using high resolution melt (HRM) profiles and normalised difference plots, we successfully differentiated the homozygous dominant (wild type), homozygous recessive (LPA) and heterozygous ...

  12. Four new single nucleotide polymorphisms (SNPs) of toll-like ...

    African Journals Online (AJOL)

    In order to reveal the single nucleotide polymorphisms (SNPs), genotypes and allelic frequencies of each mutation site of TLR7 gene in Chinese native duck breeds, SNPs of duck TLR7 gene were detected by DNA sequencing. The genotypes of 465 native ducks from eight key protected duck breeds were determined by ...

  13. Detection of new single nucleotide polymorphisms by means of real ...

    Indian Academy of Sciences (India)

    Unknown

    amplified millions to billions of times by means of a PCR before the PCR product ... Keywords. Single nucleotide polymorphism; real time PCR; DNA melting curve analysis. ... VAL158MET SNP and alcoholism and to test for interac- tions between the .... indicate a heterozygote sample (VAL/MET genotype). The curve with ...

  14. Involvement of cyclic nucleotides in locust flight muscle metabolism

    NARCIS (Netherlands)

    Worm, R.A.A.

    1980-01-01

    1. Flight had no significant effect on the levels of c-AMP of c-GMP in the flight muscles of Locusta migratoria. 2. Injections of 0.01 or 0.1 corpus cardiacum equivalents into the abdominal cavity did not elicit any effect on cyclic nucleotide levels either. 3. Injection of A23187 resulted in

  15. Analysis of single nucleotide polymorphisms in case-control studies.

    Science.gov (United States)

    Li, Yonghong; Shiffman, Dov; Oberbauer, Rainer

    2011-01-01

    Single nucleotide polymorphisms (SNPs) are the most common type of genetic variants in the human genome. SNPs are known to modify susceptibility to complex diseases. We describe and discuss methods used to identify SNPs associated with disease in case-control studies. An outline on study population selection, sample collection and genotyping platforms is presented, complemented by SNP selection, data preprocessing and analysis.

  16. Subpicosecond Dynamics in Nucleotides Measured by Spontaneous Raman Spectroscopy

    NARCIS (Netherlands)

    Terpstra, P.A.; Terpstra, P.A.; Otto, Cornelis; Greve, Jan

    1997-01-01

    The band widths in Raman spectra are sensitive to dynamics active on a time scale from 0.1 to 10 ps. The band widths of nucleotide vibrations and their dependence on temperature, concentration, and structure are reported. From the experimental band widths and second moments, it is derived that the

  17. Nucleotide excision repair II: From yeast to mammals

    NARCIS (Netherlands)

    J.H.J. Hoeijmakers (Jan)

    1993-01-01

    textabstractAn intricate network of repair systems safeguards the integrity of genetic material, by eliminating DNA lesions induced by numerous environmental and endogenous genotoxic agents. Nucleotide excision repair (NER) is one of the most versatile DNA repair systems. Deficiencies in this

  18. Nucleotide excision repair I: from E.coli to yeast.

    NARCIS (Netherlands)

    J.H.J. Hoeijmakers (Jan)

    1993-01-01

    textabstractGenetic information is constantly deteriorating, mainly as a consequence of the action of numerous genotoxic agents. In order to cope with this fundamental problem, all living organisms have acquired a complex network of DNA repair systems to safeguard their genetic integrity. Nucleotide

  19. Characterization of single nucleotide polymorphism markers for eelgrass (Zostera marina)

    NARCIS (Netherlands)

    Ferber, Steven; Reusch, Thorsten B. H.; Stam, Wytze T.; Olsen, Jeanine L.

    We characterized 37 single nucleotide polymorphism (SNP) makers for eelgrass Zostera marina. SNP markers were developed using existing EST (expressed sequence tag)-libraries to locate polymorphic loci and develop primers from the functional expressed genes that are deposited in The ZOSTERA database

  20. DNA Nucleotides Detection via capacitance properties of Graphene

    Science.gov (United States)

    Khadempar, Nahid; Berahman, Masoud; Yazdanpanah, Arash

    2016-05-01

    In the present paper a new method is suggested to detect the DNA nucleotides on a first-principles calculation of the electronic features of DNA bases which chemisorbed to a graphene sheet placed between two gold electrodes in a contact-channel-contact system. The capacitance properties of graphene in the channel are surveyed using non-equilibrium Green's function coupled with the Density Functional Theory. Thus, the capacitance properties of graphene are theoretically investigated in a biological environment, and, using a novel method, the effect of the chemisorbed DNA nucleotides on electrical charges on the surface of graphene is deciphered. Several parameters in this method are also extracted including Electrostatic energy, Induced density, induced electrostatic potential, Electron difference potential and Electron difference density. The qualitative and quantitative differences among these parameters can be used to identify DNA nucleotides. Some of the advantages of this approach include its ease and high accuracy. What distinguishes the current research is that it is the first experiment to investigate the capacitance properties of gaphene changes in the biological environment and the effect of chemisorbed DNA nucleotides on the surface of graphene on the charge.

  1. Effects of Dietary Nucleotides on Growth Rate and Disease ...

    African Journals Online (AJOL)

    Effects of dietary nucleotides on growth and disease resistance of crustaceans were evaluated using axenic Artemia culture tests. Higher Artemia growth in xenic culture (15.6 ± 2.9 mm) than in axenic culture (9.2 ± 1.9 mm) reaffirmed the need to eliminate microbial populations known to influence growth and disease ...

  2. Adiponectin Single Nucleotide Polymorphism (+276G/T) and Its ...

    African Journals Online (AJOL)

    The present study was investigating the association between the single nucleotide polymorphism +276 G/T of the adiponectin gene with serum adiponectin level in patients with coronary artery disease (CAD). In this study 100 healthy controls and 100 Egyptian patients with coronary artery disease of both genders ...

  3. The nucleotide sequences of two leghemoglobin genes from soybean

    DEFF Research Database (Denmark)

    Wiborg, O; Hyldig-Nielsen, J J; Jensen, E O

    1982-01-01

    We present the complete nucleotide sequences of two leghemoglobin genes isolated from soybean DNA. Both genes contain three intervening sequences in identical positions. Comparison of the coding sequences with known amino-acid sequences of soybean leghemoglobins suggest that the two genes...

  4. Effects of Dietary Nucleotides on Growth Rate and Disease ...

    African Journals Online (AJOL)

    Nucleotides are low molecular weight biological compounds, which are ... nutrition and disease aspects of crustaceans (Overton and Bland 1981 .... additives on growth and disease resistance. Effects of ... metabolically active cells during stressful conditions ... in humans supplemented with Uracyl, which resulted in optimal ...

  5. Nucleotide diversity and gene expression of Catalase and Glutathione peroxidase in irradiated Scots pine (Pinus sylvestris L.) from the Chernobyl exclusion zone

    International Nuclear Information System (INIS)

    Vornam, Barbara; Arkhipov, Andrey; Finkeldey, Reiner

    2012-01-01

    In the Chernobyl exclusion zone forest trees have to tolerate and to adapt to ionizing radiation, therefore the molecular basis of their adaptive responses is of the utmost interest. Based on SNP analysis and real time PCR nucleotide diversity and expression profiles of gene fragments of catalase (Cat) and glutathione peroxidase (GPx), which are known as radical scavenging genes, were analysed in the needles of irradiated pine trees of the Chernobyl exclusion zone. In acutely and chronically irradiated trees (50 years old) planted before the accident a higher nucleotide diversity of Cat and more somatic mutations were found compared to their control. Chronically irradiated trees (20 years old) planted after the accident showed a similar nucleotide diversity of Cat compared to their control and in both collectives one somatic mutation was found. The nucleotide diversity of GPx was higher in all analysed trees compared to Cat. No somatic mutation events were found in GPx. For both gene fragments, no association between the received dose in a tree and the nucleotide diversity and mutation events was detected. The expression profiles of Cat and GPx in acutely and chronically and in chronically irradiated trees were similar. Compared to their corresponding control collectives, Cat was up-regulated and GPx slightly down-regulated.

  6. Elements in nucleotide sensing and hydrolysis of the AAA+ disaggregation machine ClpB: a structure-based mechanistic dissection of a molecular motor

    Energy Technology Data Exchange (ETDEWEB)

    Zeymer, Cathleen, E-mail: cathleen.zeymer@mpimf-heidelberg.mpg.de; Barends, Thomas R. M.; Werbeck, Nicolas D.; Schlichting, Ilme; Reinstein, Jochen, E-mail: cathleen.zeymer@mpimf-heidelberg.mpg.de [Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg (Germany)

    2014-02-01

    High-resolution crystal structures together with mutational analysis and transient kinetics experiments were utilized to understand nucleotide sensing and the regulation of the ATPase cycle in an AAA+ molecular motor. ATPases of the AAA+ superfamily are large oligomeric molecular machines that remodel their substrates by converting the energy from ATP hydrolysis into mechanical force. This study focuses on the molecular chaperone ClpB, the bacterial homologue of Hsp104, which reactivates aggregated proteins under cellular stress conditions. Based on high-resolution crystal structures in different nucleotide states, mutational analysis and nucleotide-binding kinetics experiments, the ATPase cycle of the C-terminal nucleotide-binding domain (NBD2), one of the motor subunits of this AAA+ disaggregation machine, is dissected mechanistically. The results provide insights into nucleotide sensing, explaining how the conserved sensor 2 motif contributes to the discrimination between ADP and ATP binding. Furthermore, the role of a conserved active-site arginine (Arg621), which controls binding of the essential Mg{sup 2+} ion, is described. Finally, a hypothesis is presented as to how the ATPase activity is regulated by a conformational switch that involves the essential Walker A lysine. In the proposed model, an unusual side-chain conformation of this highly conserved residue stabilizes a catalytically inactive state, thereby avoiding unnecessary ATP hydrolysis.

  7. Elements in nucleotide sensing and hydrolysis of the AAA+ disaggregation machine ClpB: a structure-based mechanistic dissection of a molecular motor

    International Nuclear Information System (INIS)

    Zeymer, Cathleen; Barends, Thomas R. M.; Werbeck, Nicolas D.; Schlichting, Ilme; Reinstein, Jochen

    2014-01-01

    High-resolution crystal structures together with mutational analysis and transient kinetics experiments were utilized to understand nucleotide sensing and the regulation of the ATPase cycle in an AAA+ molecular motor. ATPases of the AAA+ superfamily are large oligomeric molecular machines that remodel their substrates by converting the energy from ATP hydrolysis into mechanical force. This study focuses on the molecular chaperone ClpB, the bacterial homologue of Hsp104, which reactivates aggregated proteins under cellular stress conditions. Based on high-resolution crystal structures in different nucleotide states, mutational analysis and nucleotide-binding kinetics experiments, the ATPase cycle of the C-terminal nucleotide-binding domain (NBD2), one of the motor subunits of this AAA+ disaggregation machine, is dissected mechanistically. The results provide insights into nucleotide sensing, explaining how the conserved sensor 2 motif contributes to the discrimination between ADP and ATP binding. Furthermore, the role of a conserved active-site arginine (Arg621), which controls binding of the essential Mg 2+ ion, is described. Finally, a hypothesis is presented as to how the ATPase activity is regulated by a conformational switch that involves the essential Walker A lysine. In the proposed model, an unusual side-chain conformation of this highly conserved residue stabilizes a catalytically inactive state, thereby avoiding unnecessary ATP hydrolysis

  8. Computational Analysis of Single Nucleotide Polymorphisms Associated with Altered Drug Responsiveness in Type 2 Diabetes

    Directory of Open Access Journals (Sweden)

    Valerio Costa

    2016-06-01

    Full Text Available Type 2 diabetes (T2D is one of the most frequent mortality causes in western countries, with rapidly increasing prevalence. Anti-diabetic drugs are the first therapeutic approach, although many patients develop drug resistance. Most drug responsiveness variability can be explained by genetic causes. Inter-individual variability is principally due to single nucleotide polymorphisms, and differential drug responsiveness has been correlated to alteration in genes involved in drug metabolism (CYP2C9 or insulin signaling (IRS1, ABCC8, KCNJ11 and PPARG. However, most genome-wide association studies did not provide clues about the contribution of DNA variations to impaired drug responsiveness. Thus, characterizing T2D drug responsiveness variants is needed to guide clinicians toward tailored therapeutic approaches. Here, we extensively investigated polymorphisms associated with altered drug response in T2D, predicting their effects in silico. Combining different computational approaches, we focused on the expression pattern of genes correlated to drug resistance and inferred evolutionary conservation of polymorphic residues, computationally predicting the biochemical properties of polymorphic proteins. Using RNA-Sequencing followed by targeted validation, we identified and experimentally confirmed that two nucleotide variations in the CAPN10 gene—currently annotated as intronic—fall within two new transcripts in this locus. Additionally, we found that a Single Nucleotide Polymorphism (SNP, currently reported as intergenic, maps to the intron of a new transcript, harboring CAPN10 and GPR35 genes, which undergoes non-sense mediated decay. Finally, we analyzed variants that fall into non-coding regulatory regions of yet underestimated functional significance, predicting that some of them can potentially affect gene expression and/or post-transcriptional regulation of mRNAs affecting the splicing.

  9. Sirtuin1 single nucleotide polymorphism (A2191G is a diagnostic marker for vibration-induced white finger disease

    Directory of Open Access Journals (Sweden)

    Voelter-Mahlknecht Susanne

    2012-10-01

    Full Text Available Abstract Background Vibration-induced white finger disease (VWF, also known as hand-arm vibration syndrome, is a secondary form of Raynaud’s disease, affecting the blood vessels and nerves. So far, little is known about the pathogenesisof the disease. VWF is associated with an episodic reduction in peripheral blood flow. Sirtuin 1, a class III histone deacetylase, has been described to regulate the endothelium dependent vasodilation by targeting endothelial nitric oxide synthase. We assessed Sirt1single nucleotide polymorphisms in patients with VWF to further elucidate the role of sirtuin 1 in the pathogenesis of VWF. Methods Peripheral blood samples were obtained from 74 patients with VWF (male 93.2%, female 6.8%, median age 53 years and from 317 healthy volunteers (gender equally distributed, below 30 years of age. Genomic DNA was extracted from peripheral blood mononuclear cells and screened for potential Sirt1single nucleotide polymorphisms. Four putative genetic polymorphisms out of 113 within the Sirt1 genomic region (NCBI Gene Reference: NM_012238.3 were assessed. Allelic discrimination was performed by TaqMan-polymerasechainreaction-based allele-specific genotyping single nucleotide polymorphism assays. Results Sirt1single nucleotide polymorphism A2191G (Assay C_25611590_10, rs35224060 was identified within Sirt1 exon 9 (amino acid position 731, Ile → Val, with differing allelic frequencies in the VWF population (A/A: 70.5%, A/G: 29.5%, G/G: 0% and the control population (A/A: 99.7%, A/G: 0.3%, G/G: 0.5%, with significance levels of P U test (two-tailed P t-test and Chi-square test with Yates correction (all two-tailed: P Conclusion We identified theSirt1A2191Gsingle nucleotide polymorphism as a diagnostic marker for VWF.

  10. Effects of polymerization and nucleotide identity on the conformational dynamics of the bacterial actin homolog MreB.

    Science.gov (United States)

    Colavin, Alexandre; Hsin, Jen; Huang, Kerwyn Casey

    2014-03-04

    The assembly of protein filaments drives many cellular processes, from nucleoid segregation, growth, and division in single cells to muscle contraction in animals. In eukaryotes, shape and motility are regulated through cycles of polymerization and depolymerization of actin cytoskeletal networks. In bacteria, the actin homolog MreB forms filaments that coordinate the cell-wall synthesis machinery to regulate rod-shaped growth and contribute to cellular stiffness through unknown mechanisms. Like actin, MreB is an ATPase and requires ATP to polymerize, and polymerization promotes nucleotide hydrolysis. However, it is unclear whether other similarities exist between MreB and actin because the two proteins share low sequence identity and have distinct cellular roles. Here, we use all-atom molecular dynamics simulations to reveal surprising parallels between MreB and actin structural dynamics. We observe that MreB exhibits actin-like polymerization-dependent structural changes, wherein polymerization induces flattening of MreB subunits, which restructures the nucleotide-binding pocket to favor hydrolysis. MreB filaments exhibited nucleotide-dependent intersubunit bending, with hydrolyzed polymers favoring a straighter conformation. We use steered simulations to demonstrate a coupling between intersubunit bending and the degree of flattening of each subunit, suggesting cooperative bending along a filament. Taken together, our results provide molecular-scale insight into the diversity of structural states of MreB and the relationships among polymerization, hydrolysis, and filament properties, which may be applicable to other members of the broad actin family.

  11. Purine alkaloid formation and CO2 gas exchange in dependence of development and of environmental factors in leaves of Coffea arabica L.

    Science.gov (United States)

    Frischknecht, P M; Eller, B M; Baumann, T W

    1982-12-01

    In the leaves of Coffea arabica L., purine alkaloid formation was estimated by analyzing the theobromine and caffeine content and by measuring the methylation rate of [2-(14)C]theobromine to [2-(14)C]caffeine in short-term experiments (6-24 h). At the same time, growth (in terms of dry weight and area), net photosynthesis (NPS), and dark respiration were determined. During leaf development, which was considered to be terminated when NPS was at a maximum (60-80 μmol g(-1) s(-1)) and dark respiration at a minimum (5-7.5 μmol g(-1) s(-1)), the content of theobromine and the velocity of caffeine formation were both found to decrease by a factor of more than 100. The close correlation between the theobromine content and the methylation rate is suspended when purine alkaloid formation is influenced by factors other than leaf development. Among these factors, temperature is the most effective: the velocity of caffeine biosynthesis is increased by raising the temperature and vice versa. Although the plants were well irrigated, a drastic decrease of NPS in the afternoon was observed under all environmental conditions tested. Light saturation was reached between 170-360 μmol m(-2) s(-1). The temperature optimum of NPS was shown to be very broad (24-33°C)m provided the adaptation time was sufficiently long.

  12. A pilot study on genetic variation in purine-rich elements in the nephrin gene promoter in type 2 diabetic patients

    Directory of Open Access Journals (Sweden)

    RODRIGO GONZÁLEZ

    2007-01-01

    Full Text Available Diabetic nephropathy (DN is one of the major complications of type 2 diabetes and is associated with coronary disease. Nephrin, a protein mainly expressed in glomeruli, is decreased in DN and other kidney diseases. Since insulin levels are misregulated in type 2 diabetes, a possible connection between DN and its decreased nephrin expression could be the presence of regulatory elements responsive to insulin in the nephrin gene (NPHS1 promoter region. In this work, using bioinformatic tools, we identified a purine-rich GAGA element in the nephrin gene promoter and conducted a genomic study in search of the presence of polymorphisms in this element and its possible association with DN in type 2 diabetic patients. We amplified and sequenced a 514 bp promoter region of 100 individuals and found no genetic variants in the purine-rich GAGA-box of the nephrin gene promoter between groups of patients with diabetes type 2 with and without renal and coronary complications, control patients without diabetes and healthy controls

  13. Purine derivative excretion and recovery of 14C-uric acid in urine of Ongole cattle given different levels of feed intake

    International Nuclear Information System (INIS)

    Soejono, M.; Yusiati, L.M.; Budhi, S.P.S.; Widyobroto, B.P.; Bachrudin, Z.

    2004-01-01

    The microbial protein supply to ruminants can be estimated based on the amount of purine derivatives (PD) excreted in the urine. Two experiments were conducted to evaluate the purine derivatives method for Ongole cattle. In the first experiment, 4 four-year old male Ongole cattle (Bos indicus) were used to calibrate the PD technique using the most common locally available feed at four levels of intake (95, 80, 60 and 40% of voluntary intake). The diet consisted of king grass and rice bran (70:30 on DM basis). The cattle at the level of 95% intake were injected with [ 14 C]-uric acid in a single dose to define the renal:non-renal partitioning ratio of plasma PD excreted in the urine. The results showed that PD excretion responded positively to the level of feed intake. The relative proportion of urinary allantoin and uric acid to PD excretion was 0.87 and 0.13 respectively. The proportion of urea N to total N ranged from 83 to 93%. The glomerular filtration rate and tubular load of PD increased due to the increasing level of feed intake. Nitrogen balance became negative when the level of feed intake decreased to 60%. The proportion of plasma PD excreted in the urine was 0.67. (author)

  14. The effect of ultraviolet light on the cyclic nucleotide system of human fibroblasts

    International Nuclear Information System (INIS)

    Fertel, R.H.; Tejwani, G.A.; Albrightson, C.R.; Hart, R.W.

    1981-01-01

    The concentrations of cyclic AMP and cyclic GMP in in human skin fibroblasts in culture were determined after exposing the cells to varying fluences of UV (254 nm) light. The cyclic nucleotide concentrations of cells irradiated in the log phase of growth were unchanged relative to controls. In contrast, there was a rise in the concentration of cyclic AMP in cells irradiated after they reached confluency. The increase in concentration was observed as early as 30 min after irradiation, reached a maximum of about 200% of control at 4 to 6 h after exposure, and returned to control values by 24 h after irradiation. The effect was proportional to a UV fluence from 5 to 20 J/m 2 , and was blocked by the addition of the UV absorbing agent para-aminobenzoic acid. In contrast, the results indicated that UV light had no effect on the concentration of cyclic GMP in human fibroblast cell cultures. Because of the importance of cyclic nucleotides in the regulation of cellular function, it is reasonable to hypothesize that changes in cyclic AMP induced by UV light may effect the extranuclear functions of irradiated cells. (author)

  15. Nucleotide excision repair- and p53-deficient mouse models in cancer research

    Energy Technology Data Exchange (ETDEWEB)

    Hoogervorst, Esther M. [Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven (Netherlands); Utrecht University, Department of Pathobiology, Utrecht (Netherlands); Steeg, Harry van [Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven (Netherlands); Vries, Annemieke de [Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven (Netherlands)]. E-mail: Annemieke.de.Vries@rivm.nl

    2005-07-01

    Cancer is caused by the loss of controlled cell growth due to mutational (in)activation of critical genes known to be involved in cell cycle regulation. Three main mechanisms are known to be involved in the prevention of cells from becoming cancerous; DNA repair and cell cycle control, important to remove DNA damage before it will be fixed into mutations and apoptosis, resulting in the elimination of cells containing severe DNA damage. Several human syndromes are known to have (partially) deficiencies in these pathways, and are therefore highly cancer prone. Examples are xeroderma pigmentosum (XP) caused by an inborn defect in the nucleotide excision repair (NER) pathway and the Li-Fraumeni syndrome, which is the result of a germ line mutation in the p53 gene. XP patients develop skin cancer on sun exposed areas at a relatively early age, whereas Li-Fraumeni patients spontaneously develop a wide variety of early onset tumors, including sarcomas, leukemia's and mammary gland carcinomas. Several mouse models have been generated to mimic these human syndromes, providing us information about the role of these particular gene defects in the tumorigenesis process. In this review, spontaneous phenotypes of mice deficient for nucleotide excision repair and/or the p53 gene will be described, together with their responses upon exposure to either chemical carcinogens or radiation. Furthermore, possible applications of these and newly generated mouse models for cancer will be given.

  16. Novel Radioligands for Cyclic Nucleotide Phosphodiesterase Imaging with Positron Emission Tomography: An Update on Developments Since 2012

    Directory of Open Access Journals (Sweden)

    Susann Schröder

    2016-05-01

    Full Text Available Cyclic nucleotide phosphodiesterases (PDEs are a class of intracellular enzymes that inactivate the secondary messenger molecules, cyclic adenosine monophosphate (cAMP and cyclic guanosine monophosphate (cGMP. Thus, PDEs regulate the signaling cascades mediated by these cyclic nucleotides and affect fundamental intracellular processes. Pharmacological inhibition of PDE activity is a promising strategy for treatment of several diseases. However, the role of the different PDEs in related pathologies is not completely clarified yet. PDE-specific radioligands enable non-invasive visualization and quantification of these enzymes by positron emission tomography (PET in vivo and provide an important translational tool for elucidation of the relationship between altered expression of PDEs and pathophysiological effects as well as (pre-clinical evaluation of novel PDE inhibitors developed as therapeutics. Herein we present an overview of novel PDE radioligands for PET published since 2012.

  17. Single nucleotide polymorphisms as susceptibility, prognostic, and therapeutic markers of nonsmall cell lung cancer

    Directory of Open Access Journals (Sweden)

    Zienolddiny S

    2011-12-01

    Full Text Available Shanbeh Zienolddiny, Vidar SkaugSection for Toxicology and Biological Work Environment, National Institute of Occupational Health, Oslo, NorwayAbstract: Lung cancer is a major public health problem throughout the world. Among the most frequent cancer types (prostate, breast, colorectal, stomach, lung, lung cancer is the leading cause of cancer-related deaths worldwide. Among the two major subtypes of small cell lung cancer and nonsmall cell lung cancer (NSCLC, 85% of tumors belong to the NSCLC histological types. Small cell lung cancer is associated with the shortest survival time. Although tobacco smoking has been recognized as the major risk factor for lung cancer, there is a great interindividual and interethnic difference in risk of developing lung cancer given exposure to similar environmental and lifestyle factors. This may indicate that in addition to chemical and environmental factors, genetic variations in the genome may contribute to risk modification. A common type of genetic variation in the genome, known as single nucleotide polymorphism, has been found to be associated with susceptibility to lung cancer. Interestingly, many of these polymorphisms are found in the genes that regulate major pathways of carcinogen metabolism (cytochrome P450 genes, detoxification (glutathione S-transferases, adduct removal (DNA repair genes, cell growth/apoptosis (TP53/MDM2, the immune system (cytokines/chemokines, and membrane receptors (nicotinic acetylcholine and dopaminergic receptors. Some of these polymorphisms have been shown to alter the level of mRNA, and protein structure and function. In addition to being susceptibility markers, several of these polymorphisms are emerging to be important for response to chemotherapy/radiotherapy and survival of patients. Therefore, it is hypothesized that single nucleotide polymorphisms will be valuable genetic markers in individual-based prognosis and therapy in future. Here we will review some of the most

  18. Preparation of protected nucleotides usable in oligonucleotide synthesis

    International Nuclear Information System (INIS)

    Debiard, Jean-Pascal

    1983-01-01

    After having presented the components of DNA, the author of this research thesis outlines that, when dealing the chemical synthesis, the respect of the sequence of these components is the main problem as each nucleotide possesses several functions which may react with each other. In order to solve this problem, functional protection is used to protect functions which may react in an undesirable way and to let free those which participate to the desired reaction. But a selective protector group must be used and this group must remain stable during the operations it is not involved in. Therefore, its elimination will be easy and without any risk of deterioration of the synthesised molecule. This research thesis first addresses the various available techniques to perform these steps, and then reports the study of possible applications of synthetic nucleotides in the field of genetic engineering [fr

  19. Identification of cyclic nucleotide gated channels using regular expressions

    KAUST Repository

    Zelman, Alice K.

    2013-09-03

    Cyclic nucleotide-gated channels (CNGCs) are nonselective cation channels found in plants, animals, and some bacteria. They have a six-transmembrane/one- pore structure, a cytosolic cyclic nucleotide-binding domain, and a cytosolic calmodulin-binding domain. Despite their functional similarities, the plant CNGC family members appear to have different conserved amino acid motifs within corresponding functional domains than animal and bacterial CNGCs do. Here we describe the development and application of methods employing plant CNGC-specific sequence motifs as diagnostic tools to identify novel candidate channels in different plants. These methods are used to evaluate the validity of annotations of putative orthologs of CNGCs from plant genomes. The methods detail how to employ regular expressions of conserved amino acids in functional domains of annotated CNGCs and together with Web tools such as PHI-BLAST and ScanProsite to identify novel candidate CNGCs in species including Physcomitrella patens. © Springer Science+Business Media New York 2013.

  20. Nucleotide sequence composition and method for detection of neisseria gonorrhoeae

    International Nuclear Information System (INIS)

    Lo, A.; Yang, H.L.

    1990-01-01

    This patent describes a composition of matter that is specific for Neisseria gonorrhoeae. It comprises: at least one nucleotide sequence for which the ratio of the amount of the sequence which hybridizes to chromosomal DNA of Neisseria gonorrhoeae to the amount of the sequence which hybridizes to chromosomal DNA of Neisseria meningitidis is greater than about five. The ratio being obtained by a method described

  1. Nucleotide sequence composition and method for detection of neisseria gonorrhoeae

    Energy Technology Data Exchange (ETDEWEB)

    Lo, A.; Yang, H.L.

    1990-02-13

    This patent describes a composition of matter that is specific for {ital Neisseria gonorrhoeae}. It comprises: at least one nucleotide sequence for which the ratio of the amount of the sequence which hybridizes to chromosomal DNA of {ital Neisseria gonorrhoeae} to the amount of the sequence which hybridizes to chromosomal DNA of {ital Neisseria meningitidis} is greater than about five. The ratio being obtained by a method described.

  2. Statistical properties of nucleotides in human chromosomes 21 and 22

    International Nuclear Information System (INIS)

    Zhang Linxi; Sun Tingting

    2005-01-01

    In this paper the statistical properties of nucleotides in human chromosomes 21 and 22 are investigated. The n-tuple Zipf analysis with n = 3, 4, 5, 6, and 7 is used in our investigation. It is found that the most common n-tuples are those which consist only of adenine (A) and thymine (T), and the rarest n-tuples are those in which GC or CG pattern appears twice. With the n-tuples become more and more frequent, the double GC or CG pattern becomes a single GC or CG pattern. The percentage of four nucleotides in the rarest ten and the most common ten n-tuples are also considered in human chromosomes 21 and 22, and different behaviors are found in the percentage of four nucleotides. Frequency of appearance of n-tuple f(r) as a function of rank r is also examined. We find the n-tuple Zipf plot shows a power-law behavior for r n-1 and a rapid decrease for r > 4 n-1 . In order to explore the interior statistical properties of human chromosomes 21 and 22 in detail, we divide the chromosome sequence into some moving windows and we discuss the percentage of ξη (ξ, η = A, C, G, T) pair in those moving windows. In some particular regions, there are some obvious changes in the percentage of ξη pair, and there maybe exist functional differences. The normalized number of repeats N 0 (l) can be described by a power law: N 0 (l) ∼ l -μ . The distance distributions P 0 (S) between two nucleotides in human chromosomes 21 and 22 are also discussed. A two-order polynomial fit exists in those distance distributions: log P 0 (S) = a + bS + cS 2 , and it is quite different from the random sequence

  3. Mitochondria as determinant of nucleotide pools and chromosomal stability

    DEFF Research Database (Denmark)

    Madsen, Claus Desler; Munch-Petersen, Birgitte; Stevnsner, Tinna

    2007-01-01

    Mitochondrial function plays an important role in multiple human diseases and mutations in the mitochondrial genome have been detected in nearly every type of cancer investigated to date. However, the mechanism underlying the interrelation is unknown. We used human cell lines depleted of mitochon...... mitochondrial activity. Our results suggest that mitochondria are central players in maintaining genomic stability and in controlling essential nuclear processes such as upholding a balanced supply of nucleotides....

  4. Prediction of Nucleotide Binding Peptides Using Star Graph Topological Indices.

    Science.gov (United States)

    Liu, Yong; Munteanu, Cristian R; Fernández Blanco, Enrique; Tan, Zhiliang; Santos Del Riego, Antonino; Pazos, Alejandro

    2015-11-01

    The nucleotide binding proteins are involved in many important cellular processes, such as transmission of genetic information or energy transfer and storage. Therefore, the screening of new peptides for this biological function is an important research topic. The current study proposes a mixed methodology to obtain the first classification model that is able to predict new nucleotide binding peptides, using only the amino acid sequence. Thus, the methodology uses a Star graph molecular descriptor of the peptide sequences and the Machine Learning technique for the best classifier. The best model represents a Random Forest classifier based on two features of the embedded and non-embedded graphs. The performance of the model is excellent, considering similar models in the field, with an Area Under the Receiver Operating Characteristic Curve (AUROC) value of 0.938 and true positive rate (TPR) of 0.886 (test subset). The prediction of new nucleotide binding peptides with this model could be useful for drug target studies in drug development. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Nucleotide sequence of tomato ringspot virus RNA-2.

    Science.gov (United States)

    Rott, M E; Tremaine, J H; Rochon, D M

    1991-07-01

    The sequence of tomato ringspot virus (TomRSV) RNA-2 has been determined. It is 7273 nucleotides in length excluding the 3' poly(A) tail and contains a single long open reading frame (ORF) of 5646 nucleotides in the positive sense beginning at position 78 and terminating at position 5723. A second in-frame AUG at position 441 is in a more favourable context for initiation of translation and may act as a site for initiation of translation. The TomRSV RNA-2 3' noncoding region is 1550 nucleotides in length. The coat protein is located in the C-terminal region of the large polypeptide and shows significant but limited amino acid sequence similarity to the putative coat proteins of the nepoviruses tomato black ring (TBRV), Hungarian grapevine chrome mosaic (GCMV) and grapevine fanleaf (GFLV). Comparisons of the coding and non-coding regions of TomRSV RNA-2 and the RNA components of TBRV, GCMV, GFLV and the comovirus cowpea mosaic virus revealed significant similarity for over 300 amino acids between the coding region immediately to the N-terminal side of the putative coat proteins of TomRSV and GFLV; very little similarity could be detected among the non-coding regions of TomRSV and any of these viruses.

  6. Function of the Nucleotide Exchange Activity of Vav1 in T cell Development and Activation*

    Science.gov (United States)

    Saveliev, Alexander; Vanes, Lesley; Ksionda, Olga; Rapley, Jonathan; Smerdon, Stephen J.; Rittinger, Katrin; Tybulewicz, Victor L. J.

    2012-01-01

    The guanine nucleotide exchange factor (GEF) Vav1 is essential for transducing T cell antigen receptor (TCR) signals and therefore plays a critical role in the development and activation of T cells. It has been presumed that the GEF activity of Vav1 is important for its function; however, there has been no direct demonstration of this. Here, we generated mice expressing enzymatically inactive, but normally folded, Vav1 protein. Analysis of these mice showed that the GEF activity of Vav1 was necessary for the selection of thymocytes and for the optimal activation of T cells, including signal transduction to Rac1, Akt, and integrins. In contrast, the GEF activity of Vav1 was not required for TCR-induced calcium flux, activation of extracellular signal–regulated kinase (ERK) and protein kinase D1 (PKD1), and cell polarization. Thus, in T cells, the GEF activity of Vav1 is essential for some, but not all, of its functions. PMID:20009105

  7. Function of the nucleotide exchange activity of vav1 in T cell development and activation.

    Science.gov (United States)

    Saveliev, Alexander; Vanes, Lesley; Ksionda, Olga; Rapley, Jonathan; Smerdon, Stephen J; Rittinger, Katrin; Tybulewicz, Victor L J

    2009-12-15

    The guanine nucleotide exchange factor (GEF) Vav1 is essential for transducing T cell antigen receptor (TCR) signals and therefore plays a critical role in the development and activation of T cells. It has been presumed that the GEF activity of Vav1 is important for its function; however, there has been no direct demonstration of this. Here, we generated mice expressing enzymatically inactive, but normally folded, Vav1 protein. Analysis of these mice showed that the GEF activity of Vav1 was necessary for the selection of thymocytes and for the optimal activation of T cells, including signal transduction to Rac1, Akt, and integrins. In contrast, the GEF activity of Vav1 was not required for TCR-induced calcium flux, activation of extracellular signal-regulated kinase and protein kinase D1, and cell polarization. Thus, in T cells, the GEF activity of Vav1 is essential for some, but not all, of its functions.

  8. Dysfunctional Hyperpolarization-Activated Cyclic Nucleotide-gated Ion Channels in Cardiac Diseases

    Directory of Open Access Journals (Sweden)

    Xiaoqi Zhao

    Full Text Available Abstract Hyperpolarization-activated cyclic nucleotide-gated (HCN channels are reverse voltage-dependent, and their activation depends on the hyperpolarization of the membrane and may be directly or indirectly regulated by the cyclic adenosine monophosphate (cAMP or other signal-transduction cascades. The distribution, quantity and activation states of HCN channels differ in tissues throughout the body. Evidence exhibits that HCN channels play critical roles in the generation and conduction of the electrical impulse and the physiopathological process of some cardiac diseases. They may constitute promising drug targets in the treatment of these cardiac diseases. Pharmacological treatment targeting HCN channels is of benefit to these cardiac conditions.

  9. Modulation of mutagenesis in eukaryotes by DNA replication fork dynamics and quality of nucleotide pools

    Science.gov (United States)

    Waisertreiger, Irina S.-R.; Liston, Victoria G.; Menezes, Miriam R.; Kim, Hyun-Min; Lobachev, Kirill S.; Stepchenkova, Elena I.; Tahirov, Tahir H.; Rogozin, Igor B.; Pavlov, Youri. I.

    2014-01-01

    The rate of mutations in eukaryotes depends on a plethora of factors and is not immediately derived from the fidelity of DNA polymerases (Pols). Replication of chromosomes containing the anti-parallel strands of duplex DNA occurs through the copying of leading and lagging strand templates by a trio of Pols α, δ and ε, with the assistance of Pol ζ and Y-family Pols at difficult DNA template structures or sites of DNA damage. The parameters of the synthesis at a given location are dictated by the quality and quantity of nucleotides in the pools, replication fork architecture, transcription status, regulation of Pol switches, and structure of chromatin. The result of these transactions is a subject of survey and editing by DNA repair. PMID:23055184

  10. The Saccharomyces cerevisiae RAD18 gene encodes a protein that contains potential zinc finger domains for nucleic acid binding and a putative nucleotide binding sequence

    Energy Technology Data Exchange (ETDEWEB)

    Jones, J.S.; Prakash, L. (Univ. of Rochester School of Medicine, NY (USA)); Weber, S. (Kodak Research Park, Rochester, NY (USA))

    1988-07-25

    The RAD18 gene of Saccharomyces cerevisiae is required for postreplication repair of UV damaged DNA. The authors have isolated the RAD18 gene, determined its nucleotide sequence and examined if deletion mutations of this gene show different or more pronounced phenotypic effects than the previously described point mutations. The RAD18 gene open reading frame encodes a protein of 487 amino acids, with a calculated molecular weight of 55,512. The RAD18 protein contains three potential zinc finger domains for nucleic acid binding, and a putative nucleotide binding sequence that is present in many proteins that bind and hydrolyze ATP. The DNA binding and nucleotide binding activities could enable the RAD18 protein to bind damaged sites in the template DNA with high affinity. Alternatively, or in addition, RAD18 protein may be a transcriptional regulator. The RAD18 deletion mutation resembles the previously described point mutations in its effects on viability, DNA repair, UV mutagenesis, and sporulation.

  11. Complexes of Escherichia coli adenylate kinase and nucleotides: 1H NMR studies of the nucleotide sites in solution

    International Nuclear Information System (INIS)

    Vetter, I.R.; Reinstein, J.; Roesch, P.

    1990-01-01

    One- and two-dimensional nuclear magnetic resonance (NMR) studies, in particular substrate-protein nuclear Overhauser effect (NOESY) measurements, as well as nucleotide and P 1 ,P 5 -bis-(5'-adenosyl) pentaphosphate (AP 5 A) titrations and studies of the temperature-dependent unfolding of the tertiary structure of Escherichia coli adenylate kinase (AK EC ) were performed. These experiments and comparison with the same type of experiments performed with the porcine enzyme led them to the following conclusions: (1) at pH 8 and concentrations of approximately 2.5-3 mM, AK EC is partially unfolded at 318 K; (2) ATP·Mg 2+ binds to the ATP site with a dissociation constant of approximately 40 μM under the assumption that ATP binds to one nucleotide site only; (3) AP 5 A·Mg 2+ binds to both nucleotide sites and thus simulates the active complex; (4) the ATP·Mg 2+ adenine in the AK EC ·AP 5 A·Mg 2+ complex is located close to His 134 and Phe 19 ; (5) the AK EC G-loop with bound ATP·Mg 2+ is structurally highly homologous to the loop region in the oncogene product p21 with bound GTP·Mg 2+

  12. An ameliorative protocol for the quantification of purine 5',8-cyclo-2'-deoxynucleosides in oxidized DNA

    Science.gov (United States)

    Terzidis, Michael; Chatgilialoglu, Chryssostomos

    2015-07-01

    5',8-Cyclo-2'-deoxyadenosine (cdA) and 5',8-cyclo-2'-deoxyguanosine (cdG) are lesions resulting from hydroxyl radical (HO•) attack on the 5'H of the nucleoside sugar moiety and exist in both 5'R and 5'S diastereomeric forms. Increased levels of cdA and cdG are linked to Nucleotide Excision Repair mechanism deficiency and mutagenesis. Discrepancies in the damage measurements reported over recent years indicated the weakness of the actual protocols, in particular for ensuring the quantitative release of these lesions from the DNA sample and the appropriate method for their analysis. Herein we report the detailed revision leading to a cost-effective and efficient protocol for the DNA damage measurement, consisting of the nuclease benzonase and nuclease P1 enzymatic combination for DNA digestion followed by liquid chromatography isotope dilution tandem mass spectrometry analysis.

  13. C-terminal β9-strand of the cyclic nucleotide-binding homology domain stabilizes activated states of Kv11.1 channels.

    Directory of Open Access Journals (Sweden)

    Chai Ann Ng

    Full Text Available Kv11.1 potassium channels are important for regulation of the normal rhythm of the heartbeat. Reduced activity of Kv11.1 channels causes long QT syndrome type 2, a disorder that increases the risk of cardiac arrhythmias and sudden cardiac arrest. Kv11.1 channels are members of the KCNH subfamily of voltage-gated K(+ channels. However, they also share many similarities with the cyclic nucleotide gated ion channel family, including having a cyclic nucleotide-binding homology (cNBH domain. Kv11.1 channels, however, are not directly regulated by cyclic nucleotides. Recently, crystal structures of the cNBH domain from mEAG and zELK channels, both members of the KCNH family of voltage-gated potassium channels, revealed that a C-terminal β9-strand in the cNBH domain occupied the putative cyclic nucleotide-binding site thereby precluding binding of cyclic nucleotides. Here we show that mutations to residues in the β9-strand affect the stability of the open state relative to the closed state of Kv11.1 channels. We also show that disrupting the structure of the β9-strand reduces the stability of the inactivated state relative to the open state. Clinical mutations located in this β9-strand result in reduced trafficking efficiency, which suggests that binding of the C-terminal β9-strand to the putative cyclic nucleotide-binding pocket is also important for assembly and trafficking of Kv11.1 channels.

  14. AVP-stimulated nucleotide secretion in perfused mouse medullary thick ascending limb and cortical collecting duct

    DEFF Research Database (Denmark)

    Odgaard, Elvin V. P.; Prætorius, Helle; Leipziger, Jens Georg

    2009-01-01

    is stimulated remain elusive. Here, we investigate the phenomenon of nucleotide secretion in intact, perfused mouse medullary thick ascending limb (mTAL) and cortical collecting duct (CCD). The nucleotide secretion was monitored by a biosensor adapted to register nucleotides in the tubular outflow...

  15. Assaying the proton transport and regulation of UCP1 using solid supported membranes.

    Science.gov (United States)

    Blesneac, Iulia; Ravaud, Stéphanie; Machillot, Paul; Zoonens, Manuela; Masscheylen, Sandrine; Miroux, Bruno; Vivaudou, Michel; Pebay-Peyroula, Eva

    2012-08-01

    The uncoupling protein 1 (UCP1) is a mitochondrial protein that carries protons across the inner mitochondrial membrane. It has an important role in non-shivering thermogenesis, and recent evidence suggests its role in human adult metabolism. Using rapid solution exchange on solid supported membranes, we succeeded in measuring electrical currents generated by the transport activity of UCP1. The protein was purified from mouse brown adipose tissue, reconstituted in liposomes and absorbed on solid supported membranes. A fast pH jump activated the ion transport, and electrical signals could be recorded. The currents were characterized by a fast rise and a slow decay, were stable over time, inhibited by purine nucleotides and activated by fatty acids. This new assay permits direct observation of UCP1 activity in controlled cell-free conditions, and opens up new possibilities for UCP1 functional characterization and drug screening because of its robustness and its potential for automation.

  16. The Tomato Nucleotide-binding Leucine-rich Repeat Immune Receptor I-2 Couples DNA-binding to Nucleotide-binding Domain Nucleotide Exchange*

    Science.gov (United States)

    Fenyk, Stepan; Dixon, Christopher H.; Gittens, William H.; Townsend, Philip D.; Sharples, Gary J.; Pålsson, Lars-Olof; Takken, Frank L. W.; Cann, Martin J.

    2016-01-01

    Plant nucleotide-binding leucine-rich repeat (NLR) proteins enable plants to recognize and respond to pathogen attack. Previously, we demonstrated that the Rx1 NLR of potato is able to bind and bend DNA in vitro. DNA binding in situ requires its genuine activation following pathogen perception. However, it is unknown whether other NLR proteins are also able to bind DNA. Nor is it known how DNA binding relates to the ATPase activity intrinsic to NLR switch function required to immune activation. Here we investigate these issues using a recombinant protein corresponding to the N-terminal coiled-coil and nucleotide-binding domain regions of the I-2 NLR of tomato. Wild type I-2 protein bound nucleic acids with a preference of ssDNA ≈ dsDNA > ssRNA, which is distinct from Rx1. I-2 induced bending and melting of DNA. Notably, ATP enhanced DNA binding relative to ADP in the wild type protein, the null P-loop mutant K207R, and the autoactive mutant S233F. DNA binding was found to activate the intrinsic ATPase activity of I-2. Because DNA binding by I-2 was decreased in the presence of ADP when compared with ATP, a cyclic mechanism emerges; activated ATP-associated I-2 binds to DNA, which enhances ATP hydrolysis, releasing ADP-bound I-2 from the DNA. Thus DNA binding is a general property of at least a subset of NLR proteins, and NLR activation is directly linked to its activity at DNA. PMID:26601946

  17. The Tomato Nucleotide-binding Leucine-rich Repeat Immune Receptor I-2 Couples DNA-binding to Nucleotide-binding Domain Nucleotide Exchange.

    Science.gov (United States)

    Fenyk, Stepan; Dixon, Christopher H; Gittens, William H; Townsend, Philip D; Sharples, Gary J; Pålsson, Lars-Olof; Takken, Frank L W; Cann, Martin J

    2016-01-15

    Plant nucleotide-binding leucine-rich repeat (NLR) proteins enable plants to recognize and respond to pathogen attack. Previously, we demonstrated that the Rx1 NLR of potato is able to bind and bend DNA in vitro. DNA binding in situ requires its genuine activation following pathogen perception. However, it is unknown whether other NLR proteins are also able to bind DNA. Nor is it known how DNA binding relates to the ATPase activity intrinsic to NLR switch function required to immune activation. Here we investigate these issues using a recombinant protein corresponding to the N-terminal coiled-coil and nucleotide-binding domain regions of the I-2 NLR of tomato. Wild type I-2 protein bound nucleic acids with a preference of ssDNA ≈ dsDNA > ssRNA, which is distinct from Rx1. I-2 induced bending and melting of DNA. Notably, ATP enhanced DNA binding relative to ADP in the wild type protein, the null P-loop mutant K207R, and the autoactive mutant S233F. DNA binding was found to activate the intrinsic ATPase activity of I-2. Because DNA binding by I-2 was decreased in the presence of ADP when compared with ATP, a cyclic mechanism emerges; activated ATP-associated I-2 binds to DNA, which enhances ATP hydrolysis, releasing ADP-bound I-2 from the DNA. Thus DNA binding is a general property of at least a subset of NLR proteins, and NLR activation is directly linked to its activity at DNA. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. The selective phosphorylation of a guanine nucleotide-binding regulatory protein

    International Nuclear Information System (INIS)

    Carlson, K.E.

    1989-01-01

    Receptor-activated signal transduction pathways regulate the responsiveness of cells to external stimuli. These transduction pathways themselves are subject to regulation, most commonly by phosphorylation. Guanine nucleotide-binding regulatory proteins (G Proteins), as requisite signal transducing elements for many plasma membrane receptors, are considered likely targets for regulation by phosphorylation. Protein kinase C (PKC) has been shown to phosphorylate the α subunit of G i and other G proteins in solution. However, the occurrence of the phosphorylation of G 1 within intact cells in response to activation of PKC has not been rigorously demonstrated. In this thesis, the extent to which the α subunits of G i undergo phosphorylation within human platelets in response to activation of PKC was examined by means of radiolabeling and immunoprecipitation. Incubation of platelets with phorbol-12-myristate-13-acetate (PMA), a potent activator of PKC, promoted the phosphorylation of several proteins within saponin-permeabilized and intact platelets incubated with [γ 32 P]ATP and [ 32 P]H 3 PO 4 , respectively. None of the phosphoproteins, however, were precipitated by either of two antisera containing antibodies differing in specificities for epitopes within G iα -despite precipitation of a substantial fraction of the subunit itself. In contrast, other antisera, containing antibodies specific for the recently describe G zα , or antibodies for both G zα and G iα , precipitated a 40-kDa phosphoprotein

  19. Regulation of cyclic AMP by extracellular ATP in cultured brain capillary endothelial cells

    Science.gov (United States)

    Anwar, Zubeya; Albert, Jennifer L; Gubby, Sharon E; Boyle, John P; Roberts, Jonathon A; Webb, Tania E; Boarder, Michael R

    1999-01-01

    In primary unpassaged rat brain capillary endothelial cell cultures (RBECs), using reverse-transcriptase PCR with primers specific for P2Y receptor subtypes, we detected mRNA for P2Y2, P2Y4 and P2Y6, but not P2Y1 receptors.None of the various nucleotides tested reduced forskolin elevated cyclic AMP levels in RBECs. ATP and ATPγS, as well as adenosine, enhanced cyclic AMP accumulation in the presence of forskolin.Comparison of the concentration response curves to ATPγS with those for ATP and adenosine, at different incubation times, indicated that the response to purine nucleotides was not wholly dependent on conversion to adenosine. Adenosine deaminase abolished the response to adenosine but only reduced the response to ATP by about 50%. These results suggest the participation of a receptor responsive to nucleotides.Isobutylmethylxanthine and 8-sulphophenyltheophylline prevented the cyclic AMP response, while neither 8-cyclopentyl-1,3-dipropylxanthine nor SCH58261 were effective antagonists. 2-chloradenosine gave a robust response, but neither 2-chloro-N6-cyclopentyladenosine nor CGS 21680 were agonists.These results show that adenosine and ATP can elevate the cyclic AMP levels of brain endothelial cells by acting on receptors which have a pharmacology apparently distinct from known P2Y and adenosine receptors. PMID:10510459

  20. A G-C-rich palindromic structural motif and a stretch of single-stranded purines are required for optimal packaging of Mason-Pfizer monkey virus (MPMV) genomic RNA.

    Science.gov (United States)

    Jaballah, Soumeya Ali; Aktar, Suriya J; Ali, Jahabar; Phillip, Pretty Susan; Al Dhaheri, Noura Salem; Jabeen, Aayesha; Rizvi, Tahir A

    2010-09-03

    During retroviral RNA packaging, two copies of genomic RNA are preferentially packaged into the budding virus particles whereas the spliced viral RNAs and the cellular RNAs are excluded during this process. Specificity towards retroviral RNA packaging is dependent upon sequences at the 5' end of the viral genome, which at times extend into Gag sequences. It has earlier been suggested that the Mason-Pfizer monkey virus (MPMV) contains packaging sequences within the 5' untranslated region (UTR) and Gag. These studies have also suggested that the packaging determinants of MPMV that lie in the UTR are bipartite and are divided into two regions both upstream and downstream of the major splice donor. However, the precise boundaries of these discontinuous regions within the UTR and the role of the intervening sequences between these dipartite sequences towards MPMV packaging have not been investigated. Employing a combination of genetic and structural prediction analyses, we have shown that region "A", immediately downstream of the primer binding site, is composed of 50 nt, whereas region "B" is composed of the last 23 nt of UTR, and the intervening 55 nt between these two discontinuous regions do not contribute towards MPMV RNA packaging. In addition, we have identified a 14-nt G-C-rich palindromic sequence (with 100% autocomplementarity) within region A that has been predicted to fold into a structural motif and is essential for optimal MPMV RNA packaging. Furthermore, we have also identified a stretch of single-stranded purines (ssPurines) within the UTR and 8 nt of these ssPurines are duplicated in region B. The native ssPurines or its repeat in region B when predicted to refold as ssPurines has been shown to be essential for RNA packaging, possibly functioning as a potential nucleocapsid binding site. Findings from this study should enhance our understanding of the steps involved in MPMV replication including RNA encapsidation process. Copyright (c) 2010 Elsevier Ltd

  1. Molecular cloning of a human glycophorin B cDNA: nucleotide sequence and genomic relationship to glycophorin A

    International Nuclear Information System (INIS)

    Siebert, P.D.; Fukuda, M.

    1987-01-01

    The authors describe the isolation and nucleotide sequence of a human glycophorin B cDNA. The cDNA was identified by differential hybridization of synthetic oligonucleotide probes to a human erythroleukemic cell line (K562) cDNA library constructed in phage vector λgt10. The nucleotide sequence of the glycophorin B cDNA was compared with that of a previously cloned glycophorin A cDNA. The nucleotide sequences encoding the NH 2 -terminal leader peptide and first 26 amino acids of the two proteins are nearly identical. This homologous region is followed by areas specific to either glycophorin A or B and a number of small regions of homology, which in turn are followed by a very homologous region encoding the presumed membrane-spanning portion of the proteins. They used RNA blot hybridization with both cDNA and synthetic oligonucleotide probes to prove our previous hypothesis that glycophorin B is encoded by a single 0.5- to 0.6-kb mRNA and to show that glycophorins A and B are negatively and coordinately regulated by a tumor-promoting phorbol ester, phorbol 12-myristate 13-acetate. They established the intron/exon structure of the glycophorin A and B genes by oligonucleotide mapping; the results suggest a complex evolution of the glycophorin genes

  2. The domain architecture of large guanine nucleotide exchange factors for the small GTP-binding protein Arf

    Directory of Open Access Journals (Sweden)

    Geldner Niko

    2005-02-01

    Full Text Available Abstract Background Small G proteins, which are essential regulators of multiple cellular functions, are activated by guanine nucleotide exchange factors (GEFs that stimulate the exchange of the tightly bound GDP nucleotide by GTP. The catalytic domain responsible for nucleotide exchange is in general associated with non-catalytic domains that define the spatio-temporal conditions of activation. In the case of small G proteins of the Arf subfamily, which are major regulators of membrane trafficking, GEFs form a heterogeneous family whose only common characteristic is the well-characterized Sec7 catalytic domain. In contrast, the function of non-catalytic domains and how they regulate/cooperate with the catalytic domain is essentially unknown. Results Based on Sec7-containing sequences from fully-annotated eukaryotic genomes, including our annotation of these sequences from Paramecium, we have investigated the domain architecture of large ArfGEFs of the BIG and GBF subfamilies, which are involved in Golgi traffic. Multiple sequence alignments combined with the analysis of predicted secondary structures, non-structured regions and splicing patterns, identifies five novel non-catalytic structural domains which are common to both subfamilies, revealing that they share a conserved modular organization. We also report a novel ArfGEF subfamily with a domain organization so far unique to alveolates, which we name TBS (TBC-Sec7. Conclusion Our analysis unifies the BIG and GBF subfamilies into a higher order subfamily, which, together with their being the only subfamilies common to all eukaryotes, suggests that they descend from a common ancestor from which species-specific ArfGEFs have subsequently evolved. Our identification of a conserved modular architecture provides a background for future functional investigation of non-catalytic domains.

  3. Crystal structure of tetraaquabis(1,3-dimethyl-2,6-dioxo-7H-purin-7-ido-κN7cobalt(II

    Directory of Open Access Journals (Sweden)

    Hicham El Hamdani

    2017-09-01

    Full Text Available The title complex, [Co(C7H7N4O22(H2O4], comprises mononuclear molecules consisting of a CoII ion, two deprotonated theophylline ligands (systematic name: 1,3-dimethyl-7H-purine-2,6-dione and four coordinating water molecules. The CoII atom lies on an inversion centre and has a slightly distorted octahedral coordination environment, with two N atoms of two trans-oriented theophylline ligands and the O atoms of four water molecules. An intramolecular hydrogen bond stabilizes this conformation. A three-dimensional supramolecular network structure is formed by intermolecular O—H...O and O—H...N hydrogen bonds.

  4. Application of Surfactant Micellar Solutions as Extractants and Mobile Phases for TLC-Determination of Purine Bases and Doping Agents in Biological Liquids

    Directory of Open Access Journals (Sweden)

    Daria Victorovna Yedamenko

    2015-04-01

    Full Text Available Separation of caffeine and its metabolites (theophylline and theobromine and doping agents (spironolactone, propranolol, and ephedrine and determination of caffeine in serum sample and propranolol and ephedrine in urine were studied on normal-phase thin layers (“Sorbfil-UV-254”. Aqueous organic solvents and aqueous micellar surfactant solutions were compared as the mobile phases for separation. The acceptable separation of purine bases and doping agents was achieved by micellar Thin Layer Chromatography and normal-phase Thin Layer Chromatography. Anionic surfactant solution with added 1-propanol was the best eluent as for caffeine, theophylline, and theobromine separation, as for doping agents. The best characteristics of caffeine extraction from serum, and propranolol and ephedrine from urine were achieved when micellar eluent based on non-ionic Tween-80 surfactant was used. DOI: http://dx.doi.org/10.17807/orbital.v7i1.632

  5. 2D QSAR studies of the inhibitory activity of a series of substituted purine derivatives against c-Src tyrosine kinase

    Directory of Open Access Journals (Sweden)

    Mukesh C. Sharma

    2016-07-01

    Full Text Available A series of 34 substituted purine analogues derivatives were subjected to quantitative structure-activity relationship analyses as inhibitors of c-Src tyrosine kinase. Partial least squares regression was applied to derive QSAR models, which were further validated for statistical significance by internal and external validation. The best QSAR model developed had a good predictive correlation coefficient (r2 of 0.8319, a significant cross-validated correlation coefficient (q2 of 0.7550, and an r2 for the external test set (pred_r2 of 0.7983. It was developed from the PLS method with descriptors including the SsCH3E-index, H-Donor Count, T_2_Cl_3, and negative correlation with SsOHcount. The current study provides better insight into the future design of more potent c-Src tyrosine kinase inhibitors prior to synthesis.

  6. Microarray Beads for Identifying Blood Group Single Nucleotide Polymorphisms

    OpenAIRE

    Drago, Francesca; Karpasitou, Katerina; Poli, Francesca

    2009-01-01

    We have developed a high-throughput system for single nucleotide polymorphism (SNP) genotyping of alleles of diverse blood group systems exploiting Luminex technology. The method uses specific oligonucleotide probes coupled to a specific array of fluorescent microspheres and is designed for typing Jka/Jkb, Fya/Fyb, S/s, K/k, Kpa/Kpb, Jsa/Jsb, Coa/Cob and Lua/Lub alleles. Briefly, two multiplex PCR reactions (PCR I and PCR II) according to the laboratory specific needs are set up. PCR I amplif...

  7. Nucleotide sequence of the triosephosphate isomerase gene from Macaca mulatta

    Energy Technology Data Exchange (ETDEWEB)

    Old, S.E.; Mohrenweiser, H.W. (Univ. of Michigan, Ann Arbor (USA))

    1988-09-26

    The triosephosphate isomerase gene from a rhesus monkey, Macaca mulatta, charon 34 library was sequenced. The human and chimpanzee enzymes differ from the rhesus enzyme at ASN 20 and GLU 198. The nucleotide sequence identity between rhesus and human is 97% in the coding region and >94% in the flanking regions. Comparison of the rhesus and chimp genes, including the intron and flanking sequences, does not suggest a mechanism for generating the two TPI peptides of proliferating cells from hominoids and a single peptide from the rhesus gene.

  8. Single nucleotide polymorphism (SNP) detection on a magnetoresistive sensor

    DEFF Research Database (Denmark)

    Rizzi, Giovanni; Østerberg, Frederik Westergaard; Dufva, Martin

    2013-01-01

    We present a magnetoresistive sensor platform for hybridization assays and demonstrate its applicability on single nucleotide polymorphism (SNP) genotyping. The sensor relies on anisotropic magnetoresistance in a new geometry with a local negative reference and uses the magnetic field from...... the sensor bias current to magnetize magnetic beads in the vicinity of the sensor. The method allows for real-time measurements of the specific bead binding to the sensor surface during DNA hybridization and washing. Compared to other magnetic biosensing platforms, our approach eliminates the need...... for external electromagnets and thus allows for miniaturization of the sensor platform....

  9. Effect of feeding tannin degrading bacterial culture (Streptococcus gallolyticus strain TDGB 406) on nutrient utilization, urinary purine derivatives and growth performance of goats fed on Quercus semicarpifolia leaves.

    Science.gov (United States)

    Kumar, K; Chaudhary, L C; Agarwal, N; Kamra, D N

    2014-10-01

    To study the effect of supplementation of tannin degrading bacterial culture (Streptococcus gallolyticus strain TDGB 406) on growth performance, nutrient utilization and urinary purine derivatives of goats fed on oak (Quercus semicarpifolia) leaves. For growth study, eighteen billy goats (4 month old, average body weight 9.50 ± 1.50 kg) were distributed into three groups of six animals each. The animals of group 1 served as control while animals of groups 2 (T1) and 3 (T2) were given (@ 5 ml/kg live weight) autoclaved and live culture of isolate TDGB 406 (10(6) cells/ml) respectively. The animals were fed measured quantity of dry oak leaves as the main roughage source and ad libitum maize hay along with fixed quantity of concentrate mixture. The feeding of live culture of isolate TDGB 406 (probiotic) did not affect dry matter intake and digestibility of nutrients except that of dry matter and crude protein, which was higher in T2 group as compared to control. All the animals were in positive nitrogen balance. There was no significant effect of feeding isolate TDGB 406 on urinary purine derivatives (microbial protein production) in goats. The body weight gain and average live weight gain was significantly higher (p = 0.071) in T2 group as compared to control. Feed conversion efficiency was also better in the goats fed on live culture of TDGB 406 (T2). The feeding of tannin degrading bacterial isolate TDGB 406 as probiotic resulted in improved growth performance and feed conversion ratio in goats fed on oak leaves as one of the main roughage source. Journal of Animal Physiology and Animal Nutrition © 2013 Blackwell Verlag GmbH.

  10. Novel cross-strand three-purine stack of the highly conserved 5'-GA/AAG-5' internal loop at the 3'-end termini of Parvovirus Genomes

    International Nuclear Information System (INIS)

    Chou, S.-H.; Chin, K.-H.

    2001-01-01

    We have used two-dimensional nuclear magnetic resonance (2D-NMR), distance geometry (DG) and molecular dynamics / energy minimization (MD/EM) methods to study a 2x3 asymmetric internal loop structure of the highly conserved '5'-(GA)/(AAG)-5' bubble' present at the 3'-end hairpin of the single-stranded DNA genome of parvoviruses. This motif contains an unpaired adenosine stacked between two bracketed sheared G·A pairs. However, the phenomenal cross-strand G-G and A-A stacking in the tandem sheared G·A pairs has undergone considerable change. A novel three-purine stacking pattern is observed instead; the inserted A18 base is completely un-stacked from its neighboring G17 and A19 bases, but well stacked with the cross-strand A4 and G3 bases to form a novel A4/A18/G3 stack that is different from the double G/G, A/A or quadruple G/G/G/G stack present in the 5'-(GA)/(AG)-5' or 5'-(GGA)/(AGG)-5' motifs. Unlike the bulged purine residue that usually causes about 20 degree kink in the helical axis of the parent helix when bracketed by canonical G·C or A·T base pairs, no significant kink is observed in the present helix containing a bulged-adenine that is bracketed by sheared G ·A pairs. The phosphodiesters connecting G3-A4 and G17-A18 residues adopt unusual ζ torsional angles close to the trans domain, yet that connecting A18-A19 residues resumes the normal ζ(g - ) value. The well structured '5'-(GAA)/(AG)-5'' internal loop in the parvovirus genomes explains its resistance to single-strand specific endonuclease susceptibility

  11. Investigation of free amino acid, total phenolics, antioxidant activity and purine alkaloids to assess the health properties of non-Camellia tea

    Directory of Open Access Journals (Sweden)

    Wu Bi

    2016-03-01

    Full Text Available To find novel functional beverages from folk teas, 33 species of frequently used non-Camellia tea (plants other than Camellia were collected and compared with Camellia tea (green tea, pu-erh tea and black tea for the first time. Data are reported here on the quantities of 20 free amino acids (FAAs and three purine alkaloids (measured by UHPLC, total polyphenols (measured by Folin-Ciocalteu assay, and antioxidant activity (DPPH. The total amounts of FAAs in non-Camellia tea (0.62–18.99 mg/g are generally less than that of Camellia tea (16.55–24.99 mg/g. However, for certain FAAs, the quantities were much higher in some non-Camellia teas, such as γ-aminobutyric acid in teas from Ampelopsis grossedentata, Isodon serra and Hibiscus sabdariffa. Interestingly, theanine was detected in tea from Potentilla fruticosa (1.16±0.81 mg/g. Furthermore, the content of polyphenols in teas from A. grossedentata, Acer tataricum subsp. ginnala are significantly higher than those from Camellia tea; teas from I. serra, Pistacia chinensis and A. tataricum subsp. ginnala have remarkable antioxidant activities similar to the activities from green tea (44.23 μg/mL. Purine alkaloids (caffeine, theobromine and theophylline were not detected in non-Camellia teas. The investigation suggest some non-Camellia teas may be great functional natural products with potential for prevention of chronic diseases and aging, by providing with abundant polyphenols, antioxidants and specific FAAs.

  12. Investigation of free amino acid, total phenolics, antioxidant activity and purine alkaloids to assess the health properties of non-Camellia tea.

    Science.gov (United States)

    Bi, Wu; He, Chunnian; Ma, Yunyun; Shen, Jie; Zhang, Linghua Harris; Peng, Yong; Xiao, Peigen

    2016-03-01

    To find novel functional beverages from folk teas, 33 species of frequently used non-Camellia tea (plants other than Camellia) were collected and compared with Camellia tea (green tea, pu-erh tea and black tea) for the first time. Data are reported here on the quantities of 20 free amino acids (FAAs) and three purine alkaloids (measured by UHPLC), total polyphenols (measured by Folin-Ciocalteu assay), and antioxidant activity (DPPH). The total amounts of FAAs in non-Camellia tea (0.62-18.99 mg/g) are generally less than that of Camellia tea (16.55-24.99 mg/g). However, for certain FAAs, the quantities were much higher in some non-Camellia teas, such as γ-aminobutyric acid in teas from Ampelopsis grossedentata, Isodon serra and Hibiscus sabdariffa. Interestingly, theanine was detected in tea from Potentilla fruticosa (1.16±0.81 mg/g). Furthermore, the content of polyphenols in teas from A. grossedentata, Acer tataricum subsp. ginnala are significantly higher than those from Camellia tea; teas from I. serra, Pistacia chinensis and A. tataricum subsp. ginnala have remarkable antioxidant activities similar to the activities from green tea (44.23 μg/mL). Purine alkaloids (caffeine, theobromine and theophylline) were not detected in non-Camellia teas. The investigation suggest some non-Camellia teas may be great functional natural products with potential for prevention of chronic diseases and aging, by providing with abundant polyphenols, antioxidants and specific FAAs.

  13. Urinary excretion of purine derivatives and its utilization as an index of microbial protein synthesis in the fore-stomach of the camel

    International Nuclear Information System (INIS)

    Guerouali, A.; Elgass, Y.; Balcells, J.

    2004-01-01

    Five experiments were carried out on camels to establish a model for estimating the microbial protein outflow from the rumen to the small intestine using the excretion rate of purine derivatives (PD) in urine. In Experiment I, a significant linear regression was established between the level of feed intake and the urinary excretion of total PD. The amount of PD excretion in urine increased by about 11 mmol PD/kg digestible organic matter intake/d with the increasing level of feeding. In Experiment II, endogenous excretion of PD was measured in four camels fasted for 5 continuous d. The endogenous excretion of PD averaged 230 μmol/kgW 0.75 /d, which was lower than values obtained in other ruminants. In Experiment III, xanthine oxidase (XO) activity in plasma, liver and intestinal tissues of three camels was measured and detected in liver and intestine, but not in the plasma. For the tissues examined, XO activity in camel was lower than values reported for cattle. In Experiment IV, when purine bases (PB) from RNA yeast were infused at increasing rates into the duodenum of two camels, urinary excretion of PD responded linearly with an average recovery rate of 52%. Nitrogen (N) content of microbes (N) was 8.0 mg/g DM and PB 100.3 μmol/g DM, with a PB/N (mmol/g) ratio of 1.26. In Experiment V, carried out under conditions similar to those in Experiment I, daily creatinine (C) excretion in urine was 0.34 ± 0.04 mmol/kgW 0.75 /d. PD/C ratios in spot samples of urine, collected several times in a d, were regressed against the measured daily PD excretion. A high correlation (R 2 =0.86) was obtained indicating that the PD/C ratio in spot samples of urine can be used with confidence to estimate the daily PD excretion in camels. (author)

  14. Solid-Phase Synthesis of Difficult Purine-Rich PNAs through Selective Hmb Incorporation: Application to the Total Synthesis of Cell Penetrating Peptide-PNAs

    Directory of Open Access Journals (Sweden)

    Julien Tailhades

    2017-10-01

    Full Text Available Antisense oligonucleotide (ASO-based drug development is gaining significant momentum following the recent FDA approval of Eteplirsen (an ASO based on phosphorodiamidate morpholino and Spinraza (2′-O-methoxyethyl-phosphorothioate in late 2016. Their attractiveness is mainly due to the backbone modifications which have improved the in vivo characteristics of oligonucleotide drugs. Another class of ASO, based on peptide nucleic acid (PNA chemistry, is also gaining popularity as a platform for development of gene-specific therapy for various disorders. However, the chemical synthesis of long PNAs, which are more target-specific, remains an ongoing challenge. Most of the reported methodology for the solid-phase synthesis of PNA suffer from poor coupling efficiency which limits production to short PNA sequences of less than 15 residues. Here, we have studied the effect of backbone modifications with Hmb (2-hydroxy-4-methoxybenzyl and Dmb (2,4-dimethoxybenzyl to ameliorate difficult couplings and reduce “on-resin” aggregation. We firstly synthesized a library of PNA dimers incorporating either Hmb or Dmb and identified that Hmb is superior to Dmb in terms of its ease of removal. Subsequently, we used Hmb backbone modification to synthesize a 22-mer purine-rich PNA, targeting dystrophin RNA splicing, which could not be synthesized by standard coupling methodology. Hmb backbone modification allowed this difficult PNA to be synthesized as well as to be continued to include a cell-penetrating peptide on the same solid support. This approach provides a novel and straightforward strategy for facile solid-phase synthesis of difficult purine-rich PNA sequences.

  15. Solid-phase synthesis of difficult purine-rich PNAs through selective Hmb incorporation: Application to the total synthesis of cell penetrating peptide-PNAs

    Science.gov (United States)

    Tailhades, Julien; Takizawa, Hotake; Gait, Michael J.; Wellings, Don A.; Wade, John D.; Aoki, Yoshitsugu; Shabanpoor, Fazel

    2017-10-01

    Antisense oligonucleotide (ASO)-based drug development is gaining significant momentum following the recent FDA approval of Eteplirsen (an ASO based on phosphorodiamidate morpholino) and Spinraza (2’-O-methoxyethyl-phosphorothioate) in late 2016. Their attractiveness is mainly due to the backbone modifications which have improved the in vivo characteristics of oligonucleotide drugs. Another class of ASO, based on peptide nucleic acid (PNA) chemistry, is also gaining popularity as a platform for development of gene-specific therapy for various disorders. However, the chemical synthesis of long PNAs, which are more target-specific, remains an ongoing challenge. Most of the reported methodology for the solid-phase synthesis of PNA suffer from poor coupling efficiency which limits production to short PNA sequences of less than 15 residues. Here we have studied the effect of backbone modifications with Hmb (2-hydroxy-4-methoxybenzyl) and Dmb (2,4-dimethoxybenzyl) to ameliorate difficult couplings and reduce “on-resin” aggregation. We firstly synthesized a library of PNA dimers incorporating either Hmb or Dmb and identified that Hmb is superior to Dmb in terms of its ease of removal. Subsequently, we used Hmb backbone modification to synthesize a 22-mer purine-rich PNA, targeting dystrophin RNA splicing, which could not be synthesized by standard coupling methodology. Hmb backbone modification allowed this difficult PNA to be synthesized as well as to be continued to include a cell-penetrating peptide on the same solid support. This approach provides a novel and straightforward strategy for facile solid-phase synthesis of difficult purine-rich PNA sequences.

  16. Modulation of the TGF-β1-induced epithelial to mesenchymal transition (EMT) mediated by P1 and P2 purine receptors in MDCK cells.

    Science.gov (United States)

    Zuccarini, Mariachiara; Giuliani, Patricia; Buccella, Silvana; Di Liberto, Valentina; Mudò, Giuseppa; Belluardo, Natale; Carluccio, Marzia; Rossini, Margherita; Condorelli, Daniele Filippo; Rathbone, Michel Piers; Caciagli, Francesco; Ciccarelli, Renata; Di Iorio, Patrizia

    2017-12-01

    Epithelial to mesenchymal transition (EMT) occurs during embryogenesis or under pathological conditions such as hypoxia, injury, chronic inflammation, or tissue fibrosis. In renal tubular epithelial cells (MDCK), TGF-β1 induces EMT by reducing or increasing epithelial or mesenchymal marker expression, respectively. In this study, we confirmed that the cAMP analogues, 8-CPT-cAMP or N6-Ph-cAMP, inhibited the TGF-β1-driven overexpression of the mesenchymal markers ZEB-1, Slug, Fibronectin, and α-SMA. Furthermore, we showed that A1, A2A, P2Y1, P2Y11, and P2X7 purine receptor agonists modulated the TGF-β1-induced EMT through the involvement of PKA and/or MAPK/ERK signaling. The stimulation of A2A receptor reduced the overexpression of the EMT-related markers, mainly through the cAMP-dependent PKA pathway, as confirmed by cell pre-treatment with Myr-PKI. Both A1 and P2Y1 receptor stimulation exacerbated the TGF-β1-driven effects, which were reduced by cell pre-treatment with the MAPK inhibitor PD98059, according to the increased ERK1/2 phosphorylation upon receptor activation. The effects induced by P2Y11 receptor activation were oppositely modulated by PKA or MAPK inhibition, in line with the dual nature of the Gs- and Gq-coupled receptor. Differently, P2X7 receptor induced, per se, similar and not additive effects compared to TGF-β1, after prolonged cell exposure to BzATP. These results suggest a putative role of purine receptors as target for anti-fibrotic agents.

  17. Nucleotide Selectivity at a Preinsertion Checkpoint of T7 RNA Polymerase Transcription Elongation.

    Science.gov (United States)

    E, Chao; Duan, Baogen; Yu, Jin

    2017-04-20

    Nucleotide selection is crucial for transcription fidelity control, in particular, for viral T7 RNA polymerase (RNAP) lack of proofreading activity. It has been recognized that multiple kinetic checkpoints exist prior to full nucleotide incorporation. In this work, we implemented intensive atomistic molecular dynamics (MD) simulations to quantify how strong the nucleotide selection is at the initial checkpoint of an elongation cycle of T7 RNAP. The incoming nucleotides bind into a preinsertion site where a critical tyrosine residue locates nearby to assist the nucleotide selection. We calculated the relative binding free energy between a noncognate nucleotide and a cognate one at a preinsertion configuration via alchemical simulations, showing that a small selection free energy or the binding free energy difference (∼3 k B T) exists between the two nucleotides. Indeed, another preinsertion configuration favored by the noncognate nucleotides was identified, which appears to be off path for further nucleotide insertion and additionally assists the nucleotide selection. By chemical master equation (CME) approach, we show that the small selection free energy at the preinsertion site along with the off-path noncognate nucleotide filtering can help substantially to reduce the error rate and to maintain the elongation rate high in the T7 RNAP transcription.

  18. Guanine nucleotide regulation of dopamine receptor agonist affinity states in rat estradiol-induced pituitary tumors

    Energy Technology Data Exchange (ETDEWEB)

    Di Paolo, T.; Falardeau, P.

    1987-08-31

    The authors have investigated dopamine (DA) receptor agonist high- and low-affinity states in female rate estradiol-induced prolactin (PRL)-secreting pituitary tumors and intact pituitary tissue. Estradiol treatment increased the anterior pituitary weight 9-fold and plasma prolactin levels 74-fold and these measures are correlated (R = 0.745, n = 73, p < 0.001). Competition for (/sup 3/H)-spiperone binding to the DA receptor by apomorphine was compared in normal and adenomatous pituitary tissue. The inhibition constants (Ki) and the proportions of the two apomorphine sites are unchanged in tumors compared to intact pituitary tissue. Guanosine 5'-(..beta..-..gamma..-imino)triphosphate (Gpp(NH)p) causes complete conversion of the high into low affinity dopaminergic agonist site in normal pituitary and in tumors. These results suggest that rats with primary estradiol-induced pituitary tumors have normal and functional DA receptors. 9 references, 2 tables.

  19. Guanine nucleotide regulation of dopamine receptor agonist affinity states in rat estradiol-induced pituitary tumors

    International Nuclear Information System (INIS)

    Di Paolo, T.; Falardeau, P.

    1987-01-01

    The authors have investigated dopamine (DA) receptor agonist high- and low-affinity states in female rate estradiol-induced prolactin (PRL)-secreting pituitary tumors and intact pituitary tissue. Estradiol treatment increased the anterior pituitary weight 9-fold and plasma prolactin levels 74-fold and these measures are correlated (R = 0.745, n = 73, p 3 H]-spiperone binding to the DA receptor by apomorphine was compared in normal and adenomatous pituitary tissue. The inhibition constants (Ki) and the proportions of the two apomorphine sites are unchanged in tumors compared to intact pituitary tissue. Guanosine 5'-[β-γ-imino]triphosphate (Gpp(NH)p) causes complete conversion of the high into low affinity dopaminergic agonist site in normal pituitary and in tumors. These results suggest that rats with primary estradiol-induced pituitary tumors have normal and functional DA receptors. 9 references, 2 tables

  20. Dynamic regulation of the transcription initiation landscape at single nucleotide resolution during vertebrate embryogenesis

    NARCIS (Netherlands)

    C. Nepal (Chirag); Y. Hadzhiev (Yavor); C. Previti (Christopher); V. Haberle (Vanja); N. Li (Nan); H. Takahashi (Hiroyuki); A.M. Suzuki (Ana Maria); Y. Sheng (Ying); R.F. Abdelhamid (Rehab); S. Anand (Santosh); P.A. Gehrig (Paola A.); A. Akalin (Altuna); C. Kockx (Christel); A. Van Der Sloot (Antoine); W.F.J. van IJcken (Wilfred); O. Armant (Olivier); S. Rastegar (Sepand); C. Watson (Craig); U. Strähle (Uwe); E. Stupka (Elia); P. Carninci (Piero); B. Lenhard (Boris); F. Müller (Ferenc)

    2013-01-01

    textabstractSpatiotemporal control of gene expression is central to animal development. Core promoters represent a previously unanticipated regulatory level by interacting with cis-regulatory elements and transcription initiation in different physiological and developmental contexts. Here, we