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Journal articles on the topic 'AdoMet analogue'

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Published: 4 June 2021
Last updated: 19 February 2022

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1

Bitonti, A. J., T. L. Bush, and P. P. McCann. "Regulation of polyamine biosynthesis in rat hepatoma (HTC) cells by a bisbenzyl polyamine analogue." Biochemical Journal 257, no. 3 (1989): 769–74. http://dx.doi.org/10.1042/bj2570769.

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A bisbenzyl polyamine analogue, MDL 27695, rapidly repressed ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (AdoMet DC) activity and depleted polyamines in rat hepatoma (HTC) cells. The suppression of ODC and AdoMet DC activity was temporally related to metabolism of MDL 27695 by intracellular polyamine oxidase to a free-amine analogue, MDL 26752, which, when added directly to HTC cells, suppressed ODC activity and polyamine biosynthesis more rapidly and to a greater extent than did the bisbenzyl analogue. The ODC suppression caused by MDL 27695 was completely blocked by the addition of a polyamine oxidase inhibitor to the HTC-cell cultures along with MDL 27695. These data suggested that MDL 27695 acted as a prodrug, with metabolism to an active analogue being necessary for ODC repression to occur. MDL 27695 and MDL 26752 completely abolished division of HTC cells when added to cultures at 1 microM. This established them as being among the most potent antiproliferative polyamine analogues yet described. MDL 27695 has also been shown to possess significant antimalarial effects both in vitro and in vivo, and it is possible that the marked suppression of polyamine biosynthesis described herein may contribute to its anti-malarial effects as well as its antiproliferative effects in mammalian cells.
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2

Kramer, D. L., J. R. Sufrin, and C. W. Porter. "Modulation of polyamine-biosynthetic activity by S-adenosylmethionine depletion." Biochemical Journal 249, no. 2 (1988): 581–86. http://dx.doi.org/10.1042/bj2490581.

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The methionine-analogue inhibitor of S-adenosylmethionine (AdoMet) synthetase, L-2-amino-4-methoxy-cis-but-3-enoic acid (L-cisAMB), was used to study the early effects of AdoMet depletion on polyamine biosynthesis. In the presence of decreased methionine (30 microM) in the medium, treatment of cultured L1210 cells with 1 mM-L-cisAMB resulted in a near-total (95%) depletion of cellular AdoMet pools by 4 h. This was accompanied by a 3-fold increase in ornithine decarboxylase (ODC) activity, a 2.5-fold increase in AdoMet decarboxylase (AdoMetDC) activity and a 20% decrease in spermidine and spermine pools. The increase in enzyme activities seemed to be partially due to prolongation of enzyme activity half-life, since that of ODC was extended from 30 to 50 min and that of AdoMetDC from 65 to 310 min. By temporal sequence characterization (0-4 h), the onset of elevations of enzyme activity (0.5-1 h) seemed to be causally related to an earlier (0-0.5 h) decline in AdoMet pools, as opposed to the 20% decrease in spermidine and spermine pools, which occurred much later (2-4 h); the latter are known to regulate decarboxylase activities negatively. Drug-induced elevations in ODC and, to a lesser extent, AdoMetDC activities were reversed by later treatment with exogenous AdoMet. However, because the latter also increased spermine pools (which could not be prevented with various enzyme inhibitors), the reversal of elevations in enzyme activities could not be directly linked to AdoMet. Although not definitive, the data raise the interesting possibility that, in addition to being negatively regulated by polyamines, ODC and AdoMetDC activities may also be subject to negative control by cellular AdoMet (or an AdoMet metabolite). The net effect of either or both of these influences would be to conserve polyamine-biosynthetic activity in the face of declining AdoMet supplies.
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3

Byers, T. L., T. L. Bush, P. P. McCann, and A. J. Bitonti. "Antitrypanosomal effects of polyamine biosynthesis inhibitors correlate with increases in Trypanosoma brucei brucei S-adenosyl-l-methionine." Biochemical Journal 274, no. 2 (1991): 527–33. http://dx.doi.org/10.1042/bj2740527.

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We reported recently that administration of ([(Z)-4-amino-2-butenyl]methylamino)-5′-deoxyadenosine (MDL 73811), an enzyme-activated irreversible inhibitor of S-adenosyl-L-methionine decarboxylase (AdoMetDC; EC 4.1.1.50), a key enzyme in the synthesis of spermidine, cures African trypanosome infections in mice. The precise mechanism of action of MDL 73811 was not clear because a rapid disappearance of trypanosomes from the bloodstream of treated rats occurred before significant depletion of spermidine. Administration of MDL 73811 to Trypanosoma brucei brucei-infected rats resulted in a 70% decrease in parasitaemia within 1 h and a complete disappearance of parasites by 5 h. The reduction in parasitaemia was accompanied by complete inhibition of AdoMetDC activity by 10 min after injection of MDL 73811; inhibition was sustained for at least 4 h. Polyamine levels in trypanosomes were unaffected during the first 1 h in which the marked decrease in parasitaemia was observed, but parasite AdoMet levels increased 20-fold within this time. In contrast, exposure of cultured mammalian cells to MDL 73811 resulted in only a 1.5-2-fold increase in AdoMet levels over a 6 h time course. Experiments with inhibitors of ornithine decarboxylase (ODC) also suggested that the increased AdoMet levels might be an important factor for antitrypanosomal efficacy. Trypanosomes taken from rats treated for 36 h with eflornithine, an inhibitor of ODC, were depleted of putrescine and had markedly decreased spermidine levels. These organisms also had less than 10% of control AdoMetDC activity, and had elevated decarboxy AdoMet (greater than 4000-fold) and AdoMet (up to 50-fold) levels. The methyl ester of alpha-monofluromethyl-3,4-dehydro-ornithine (delta-MFMO-CH3), which cures murine T. b. brucei infections, and the ethyl ester analogue of this compound (delta-MFMO-C2H5), which does not cure this infection, become ODC inhibitors upon hydrolysis and thus were tested for their effects on trypanosomal polyamines, AdoMet and decarboxy AdoMet levels. Although both esters of delta-MFMO depleted trypanosomal polyamines, AdoMet and decarboxy AdoMet levels were elevated in T. b. brucei from infected mice treated with delta-MFMO-CH3 but not in parasites from mice treated with the delta-MFMO-C2H5. These data suggest that inhibition of AdoMetDC, either directly with MDL 73811 or indirectly with inhibitors of ODC, apparently leads to a trypanosome-specific elevation of AdoMet. It is possible that major changes in AdoMet, rather than changes in polyamines, may be responsible for the antitrypanosomal effects of these drugs.
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4

Kramer, D. L., J. R. Sufrin, and C. W. Porter. "Relative effects of S-adenosylmethionine depletion on nucleic acid methylation and polyamine biosynthesis." Biochemical Journal 247, no. 2 (1987): 259–65. http://dx.doi.org/10.1042/bj2470259.

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Treatment of cultured L1210 cells with 1 mM-L-2-amino-4-methoxy-cis-but-3-enoic acid (L-cisAMB), a methionine-analogue inhibitor of S-adenosylmethionine (AdoMet) synthetase (EC 2.5.1.6), produced a rapid and near-total depletion of AdoMet by 4 h. After this, the pools recovered to 60% of control by 48 h, apparently because of an increase in AdoMet synthetase activity. Both AdoMet depletion and the accompanying increase in synthetase activity were substantially enhanced by lowering methionine concentrations in the media from 100 microM to 30 microM, the minimal concentration that supports cell growth at control values. During a 4 h incubation in media containing 30 microM-methionine, 1-5 mM-L-cisAMB depleted cellular AdoMet to undetectable values, and inhibited nucleic acid methylation by 44-72% and RNA methylation by 60-87%. Under these same treatment conditions, putrescine pools increased by about 3-fold, whereas spermidine pools decreased by only 20% and spermine pools remained the same. Pool changes were accompanied by a 2-4-fold increase in ornithine decarboxylase activities and AdoMet activities. Thus the rapid depletion of AdoMet pools by L-cisAMB results immediately in a decrease in methyl-transfer reactions involving nucleic acids, whereas, by contrast, biosynthesis of higher polyamines appears to be minimally affected, owing to compensatory increases in key enzyme activities.
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5

Barra, José L., Mario R. Mautino, and Alberto L. Rosa. "A Dominant Negative Effect of eth-1r, a Mutant Allele of the Neurospora crassa S-Adenosylmethionine Synthetase-Encoding Gene Conferring Resistance to the Methionine Toxic Analogue Ethionine." Genetics 144, no. 4 (1996): 1455–62. http://dx.doi.org/10.1093/genetics/144.4.1455.

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eth-1r a thermosensitive allele of the Neurospora crassa S-adenosylmethionine (AdoMet) synthetase gene that confers ethionine resistance, has been cloned and sequenced. Replacement of an aspartic amino acid residue (D48 → N48), perfectly conserved in prokaryotic, fungal and higher eukaryotic AdoMet synthetases, was found responsible for both thermosensitivity and ethionine resistance conferred by eth-1r. Gene fusion constructs, designed to overexpress eth-1r in vivo, render transformant cells resistant to ethionine. Dominance of ethionine resistance was further demonstrated in eth-1 +/eth-1r partial diploids carrying identical gene doses of both alleles. Heterozygous eth-1 +/eth-1r cells have, at the same time, both the thermotolerance conferred by eth-1 + and the ethionine-resistant phenotype conferred by eth-1r. AdoMet levels and AdoMet synthetase activities were dramatically decreased in heterozygous eth-1 +/eth-1r cells. We propose that this negative effect exerted by eth-1r results from the in vivo formation of heteromeric eth-1 +/eth-1r AdoMet synthetase molecules.
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6

Willnow, Sophie, Michael Martin, Bernhard Lüscher, and Elmar Weinhold. "A Selenium-Based Click AdoMet Analogue for Versatile Substrate Labeling with Wild-Type Protein Methyltransferases." ChemBioChem 13, no. 8 (2012): 1167–73. http://dx.doi.org/10.1002/cbic.201100781.

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7

Raghavendra, Nidhanapati K., and Desirazu N. Rao. "Exogenous AdoMet and its analogue sinefungin differentially influence DNA cleavage by R.EcoP15I—Usefulness in SAGE." Biochemical and Biophysical Research Communications 334, no. 3 (2005): 803–11. http://dx.doi.org/10.1016/j.bbrc.2005.06.171.

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8

Blackburn, G. Michael, David P. Hornby, Abdelaziz Mekhalfia, and Paul Shore. "Synthesis and biological evaluation of (S)-AzaAdoMet, a stahle isosteric and isoelectronic analogue of AdoMet, S-adenosyl L-methionine." Collection of Czechoslovak Chemical Communications 58, s1 (1993): 116–19. http://dx.doi.org/10.1135/cccc1993s116.

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9

Thompson, Mark J., Abdelaziz Mekhalfia, David L. Jakeman, et al. "Homochiral synthesis of an aza analogue of S-adenosyl-L-methionine (AdoMet) and its binding to the E. coli methionine repressor protein (MetJ)." Chemical Communications, no. 6 (1996): 791. http://dx.doi.org/10.1039/cc9960000791.

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10

THOMPSON, M. J., A. MEKHALFIA, D. L. JAKEMAN, et al. "ChemInform Abstract: Homochiral Synthesis of an Aza Analogue of S-Adenosyl-L-methionine ( AdoMet) and Its Binding to the E. coli Methionine Repressor Protein ( MetJ)." ChemInform 27, no. 36 (2010): no. http://dx.doi.org/10.1002/chin.199636227.

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11

Cornelissen, Nicolas V., Freideriki Michailidou, Fabian Muttach, Kristina Rau, and Andrea Rentmeister. "Nucleoside-modified AdoMet analogues for differential methyltransferase targeting." Chemical Communications 56, no. 14 (2020): 2115–18. http://dx.doi.org/10.1039/c9cc07807j.

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Methyltransferases modify a wide range of biomolecules using S-adenosyl-l-methionine (AdoMet) as cosubstrate. Enzymatic generation of nucleoside-modified AdoMet analogues and conversion by different methyltransferases is shown.
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12

Ndjonka, D., Y. Zou, X. Bi, P. Woster, R. D. Walter, and K. Lüersen. "The Activator-Binding Site of Onchocerca volvulus S-Adenosylmethionine Decarboxylase, a Potential Drug Target." Biological Chemistry 384, no. 8 (2003): 1195–201. http://dx.doi.org/10.1515/bc.2003.132.

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Abstract S-Adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in polyamine biosynthesis. In many eukaryotes its activity is stimulated specifically by putrescine. The AdoMetDC of the filarial parasite Onchocerca volvulus, however, is not only stimulated by putrescine but also by the naturally occuring polyamines spermidine and spermine. Several diamines, acetylated polyamines and polyamine analogues were used to analyse what molecular prerequisites are needed to stimulate nematode AdoMetDC activity. In the absence of an activator, the O. volvulus enzyme exhibits an extremely low specific activity. This fact, together with the unspecificity of activator binding, was thought to be useful for a new strategy to inhibit nematode AdoMetDC activity. Therefore, different polyamine analogues were tested as competitive inhibitors towards the stimulatory effect putrescine has on the O. volvulus and, in comparison, on the Caenorhabditis elegans and human AdoMetDC. Bis(aralkyl)- and bis(alkyl)-substituted polyamine analogues with a 3-7-3 backbone were found to inhibit AdoMetDC activities, however, probably without interfering with the putrescine stimulation. The best inhibitor, BW-1, was about 10-fold more effective against O. volvulus AdoMetDC than against the human enzyme. Unexpectedly, BW-1 was determined to be a competitive inhibitor with respect to AdoMet, having a Ki value of 310 uM for the putrescine-stimulated human AdoMetDC. Furthermore, we show for the O. volvulus and the human enzyme that the degree of inhibition by BW-1 depends on the actual putrescine concentration.
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13

Lukinavičius, Gražvydas, Miglė Tomkuvienė, Viktoras Masevičius, and Saulius Klimašauskas. "Enhanced Chemical Stability of AdoMet Analogues for Improved Methyltransferase-Directed Labeling of DNA." ACS Chemical Biology 8, no. 6 (2013): 1134–39. http://dx.doi.org/10.1021/cb300669x.

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14

Zhou, Yi, Junjie Zhan, Rui Chen, et al. "Analogue Optical Spatiotemporal Differentiator." Advanced Optical Materials 9, no. 10 (2021): 2002088. http://dx.doi.org/10.1002/adom.202002088.

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15

ZINGG, Jean-Marc, Jiang-Cheng SHEN, and Peter A. JONES. "Enzyme-mediated cytosine deamination by the bacterial methyltransferase M.MspI." Biochemical Journal 332, no. 1 (1998): 223–30. http://dx.doi.org/10.1042/bj3320223.

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Most prokaryotic (cytosine-5)-DNA methyltransferases increase the frequency of deamination at the cytosine targeted for methylation in vitro in the absence of the cofactor S-adenosylmethionine (AdoMet) or the reaction product S-adenosylhomocysteine (AdoHcy). We show here that, under the same in vitro conditions, the prokaryotic methyltransferase, M.MspI (from Moraxella sp.), causes very few cytosine deaminations, suggesting a mechanism in which M.MspI may avoid enzyme-mediated cytosine deamination. Two analogues of AdoMet, sinefungin and 5´-amino-5´-deoxyadenosine, greatly increased the frequency of cytosine deamination mediated by M.MspI presumably by introducing a proton-donating amino group into the catalytic centre, thus facilitating the formation of an unstable enzyme–dihydrocytosine intermediate and hydrolytic deamination. Interestingly, two naturally occurring analogues, adenosine and 5´-methylthio-5´-deoxyadenosine, which do not contain a proton-donating amino group, also weakly increased the deamination frequency by M.MspI, even in the presence of AdoMet or AdoHcy. These analogues may trigger a conformational change in the enzyme without completely inhibiting the access of solvent water to the catalytic centre, thus allowing hydrolytic deamination of the enzyme–dihydrocytosine intermediate. Under normal physiological conditions the enzymes M.HpaII (from Haemophilus parainfluenzae), M.HhaI (from Haemophilus hemolytica) and M.MspI all increased the in vivo deamination frequency at the target cytosines with comparable efficiency.
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16

Porter, C. W., J. McManis, D. Lee, and R. J. Bergeron. "Selective regulation of S-adenosylmethionine decarboxylase activity by the spermine analogue 6-spermyne." Biochemical Journal 254, no. 2 (1988): 337–42. http://dx.doi.org/10.1042/bj2540337.

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Polyamine-biosynthesis activity is known to be negatively regulated by intracellular polyamine pools. Accordingly, treatment of cultured L1210 cells with 10 microM-spermine rapidly and significantly lowered ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC) activities in a sequential manner. By contrast, treatment for 48 h with 10 microM of the unsaturated spermine analogue 6-spermyne lowered AdoMetDC activity, but not ODC activity. An initial decrease in ODC activity at 2 h was attributed to a transient increase in free intracellular spermidine and spermine brought about through their displacement by the analogue. Thereafter, ODC activity recovered steadily to control values as 6-spermyne pools increased and spermidine and spermine pools decreased owing to analogue suppression of AdoMetDC activity. The apparent ability of 6-spermyne to regulate AdoMetDC, but not ODC, activity suggests an interesting structure-function correlation and demonstrates that the typical co-regulation of these enzyme activities can be dissociated. This, in turn, may reflect the existence of independent regulatory binding sites for the two enzymes.
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17

Muttach, Fabian, Florian Mäsing, Armido Studer, and Andrea Rentmeister. "New AdoMet Analogues as Tools for Enzymatic Transfer of Photo-Cross-Linkers and Capturing RNA-Protein Interactions." Chemistry - A European Journal 23, no. 25 (2017): 5988–93. http://dx.doi.org/10.1002/chem.201605663.

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18

Porter, C. W., A. E. Pegg, B. Ganis, R. Madhabala, and R. J. Bergeron. "Combined regulation of ornithine and S-adenosylmethionine decarboxylases by spermine and the spermine analogue N1N12-bis(ethyl)spermine." Biochemical Journal 268, no. 1 (1990): 207–12. http://dx.doi.org/10.1042/bj2680207.

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In the present study, the spermine (SPM) analogue N1N12-bis(ethyl)spermine (BESPM) is compared with SPM in its ability to regulate ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (AdoMetDC) activities in intact L1210 cells and in the mechanism(s) by which this is accomplished. Unlike the comparable spermidine (SPD) analogue N1N8-bis(ethyl)spermidine, which regulates only ODC, BESPM suppresses both ODC and AdoMetDC activities. With 1 microM-SPM or -BESPM, near-maximal suppression of enzyme activity (i.e. less than 70%) was achieved after 2 h for ODC and 12 h for AdoMetDC. After such treatment, ODC activity fully recovered within 2-4 h, and that of AdoMetDC within 12 h, when cells were reseeded into drug-free media. It was deduced that an intracellular accumulation of BESPM or SPM equivalent to only approximately 200-450 pmol/10(6) cells was sufficient to fully invoke ODC regulatory mechanisms. Decreases in both enzyme activities after BESPM or SPM treatment were closely paralleled by concomitant decreases in the amount of enzyme protein. Since cellular ODC or AdoMetDC mRNA was not similarly decreased by either BESPM or SPM treatment, it was concluded that translational and/or post-translational mechanisms were probably responsible for enzyme regulation. In support of the former of these possibilities, it was demonstrated that both BESPM and SPM preferentially inhibited the translation in vitro of ODC and AdoMetDC relative to albumin in a reticulocyte-lysate system. On the basis of the consistent similarities between BESPM and SPM in all parameters studied, it is concluded that the analogue most likely acts by mechanisms identical with those by which SPM acts in suppressing polyamine biosynthesis.
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19

Chen, Ming Zheng, Qiang Cheng, Fen Xia, et al. "Metasurface‐Based Spatial Phasers for Analogue Signal Processing." Advanced Optical Materials 8, no. 18 (2020): 2000128. http://dx.doi.org/10.1002/adom.202000128.

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20

Jung, Hyunseung, Chihun In, Hyunyong Choi, and Hojin Lee. "Electromagnetically Induced Transparency Analogue by Self-Complementary Terahertz Meta-Atom." Advanced Optical Materials 4, no. 4 (2016): 627–33. http://dx.doi.org/10.1002/adom.201500620.

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21

Liu, Chang, Yan-Gang Miao, Yu-Mei Wu, and Yu-Hao Zhang. "Self-Regular Black Holes Quantized by means of an Analogue to Hydrogen Atoms." Advances in High Energy Physics 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/5982482.

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We suggest a quantum black hole model that is based on an analogue to hydrogen atoms. A self-regular Schwarzschild-AdS black hole is investigated, where the mass density of the extreme black hole is given by the probability density of the ground state of hydrogen atoms and the mass densities of nonextreme black holes are given by the probability densities of excited states with no angular momenta. Such an analogue is inclined to adopt quantization of black hole horizons. In this way, the total mass of black holes is quantized. Furthermore, the quantum hoop conjecture and the Correspondence Principle are discussed.
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22

Absalom, Nathan, Izumi Yamamoto, David O'Hagan, Luke Hunter, and Mary Chebib. "Probing the Mode of Neurotransmitter Binding to GABA Receptors Using Selectively Fluorinated GABA Analogues." Australian Journal of Chemistry 68, no. 1 (2015): 23. http://dx.doi.org/10.1071/ch14456.

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Stereoselective fluorination is a useful technique for controlling the conformations of organic molecules. This concept has been exploited to create conformationally biased analogues of the neurotransmitter gamma-aminobutyric acid (GABA). Mono- and di-fluorinated GABA analogues are found to adopt different conformations, due to subtle stereoelectronic effects associated with the C–F bond. These conformationally biased GABA analogues exhibit different shape-dependent selectivity patterns towards GABAA, GABAB, and GABAC receptors, providing valuable information on the binding modes of the natural ligand at these medicinally important targets.
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23

Virgilio, A., T. Amato, L. Petraccone, et al. "Improved thrombin binding aptamer analogues containing inversion of polarity sites: structural effects of extra-residues at the ends." Organic & Biomolecular Chemistry 14, no. 32 (2016): 7707–14. http://dx.doi.org/10.1039/c6ob00931j.

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24

Decroly, Etienne, Isabelle Imbert, Bruno Coutard, et al. "Coronavirus Nonstructural Protein 16 Is a Cap-0 Binding Enzyme Possessing (Nucleoside-2′O)-Methyltransferase Activity." Journal of Virology 82, no. 16 (2008): 8071–84. http://dx.doi.org/10.1128/jvi.00407-08.

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ABSTRACT The coronavirus family of positive-strand RNA viruses includes important pathogens of livestock, companion animals, and humans, including the severe acute respiratory syndrome coronavirus that was responsible for a worldwide outbreak in 2003. The unusually complex coronavirus replicase/transcriptase is comprised of 15 or 16 virus-specific subunits that are autoproteolytically derived from two large polyproteins. In line with bioinformatics predictions, we now show that feline coronavirus (FCoV) nonstructural protein 16 (nsp16) possesses an S-adenosyl-l-methionine (AdoMet)-dependent RNA (nucleoside-2′O)-methyltransferase (2′O-MTase) activity that is capable of cap-1 formation. Purified recombinant FCoV nsp16 selectively binds to short capped RNAs. Remarkably, an N7-methyl guanosine cap (7MeGpppAC3-6) is a prerequisite for binding. High-performance liquid chromatography analysis demonstrated that nsp16 mediates methyl transfer from AdoMet to the 2′O position of the first transcribed nucleotide, thus converting 7MeGpppAC3-6 into 7MeGpppA2′ O MeC3-6. The characterization of 11 nsp16 mutants supported the previous identification of residues K45, D129, K169, and E202 as the putative K-D-K-E catalytic tetrad of the enzyme. Furthermore, residues Y29 and F173 of FCoV nsp16, which may be the functional counterparts of aromatic residues involved in substrate recognition by the vaccinia virus MTase VP39, were found to be essential for both substrate binding and 2′O-MTase activity. Finally, the weak inhibition profile of different AdoMet analogues indicates that nsp16 has evolved an atypical AdoMet binding site. Our results suggest that coronavirus mRNA carries a cap-1, onto which 2′O methylation follows an order of events in which 2′O-methyl transfer must be preceded by guanine N7 methylation, with the latter step being performed by a yet-unknown N7-specific MTase.
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25

Tonali, Nicolo, Isabelle Correia, Jacopo Lesma, Guillaume Bernadat, Sandrine Ongeri та Olivier Lequin. "Introducing sequential aza-amino acids units induces repeated β-turns and helical conformations in peptides". Organic & Biomolecular Chemistry 18, № 18 (2020): 3452–58. http://dx.doi.org/10.1039/c9ob02654a.

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A major current issue in medicinal chemistry is the design of small peptide analogues resistant to proteolysis and able to adopt preferential conformations, while preserving the selectivity and efficiency of natural peptides.
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26

Jung, Hyunseung, Chihun In, Hyunyong Choi, and Hojin Lee. "Metamaterials: Electromagnetically Induced Transparency Analogue by Self-Complementary Terahertz Meta-Atom (Advanced Optical Materials 4/2016)." Advanced Optical Materials 4, no. 4 (2016): 490. http://dx.doi.org/10.1002/adom.201670019.

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27

Tchesnokov, Egor P., Ben A. Bailey-Elkin, Brian L. Mark, and Matthias Götte. "Independent Inhibition of the Polymerase and Deubiquitinase Activities of the Crimean–Congo Hemorrhagic Fever Virus Full-Length L-Protein." Proceedings 50, no. 1 (2020): 41. http://dx.doi.org/10.3390/proceedings2020050041.

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The Crimean–Congo hemorrhagic fever virus (CCHFV) is a segmented negative-sense RNA virus that can cause severe human disease. The World Health Organization (WHO) has listed CCHFV as a priority pathogen with an urgent need for enhanced research activities to develop effective countermeasures. We report on the expression, characterization, and inhibition of the CCHFV full-length L-protein that provides an important tool in this regard. The requirements for high biosafety measures hamper drug discovery and development efforts with infectious CCHFV. Hence, we decided to adopt a biochemical approach that targets the viral RNA-dependent RNA polymerase (RdRp). The CCHFV RdRp activity is part of a multifunctional L protein that is unusually large, with a molecular weight of ~450 kDa. The CCHFV L-protein also contains an ovarian tumor (OTU) domain that exhibits deubiquitinating (DUB) activity. Previous studies have shown that DUB activity interferes with innate immune responses and viral replication. Here, we utilized the baculovirus expression system and generated a full-length CCHFV L protein. RdRp activity was seen in the presence of divalent metal ions, and inhibition of RNA synthesis was demonstrated with nucleotide analogues. The ubiquitin analogue CC.4 inhibits the CCHFV-associated DUB activity of the full-length L protein and the isolated DUB domain to a similar extent. We have finally shown that RdRp and DUB activities are functionally independent. The full-length CCHFV L-protein provides an important tool for the discovery of antiviral agents. High-throughput screening (HTS) campaigns are now feasible. The same enzyme preparations can be utilized to identify polymerase and DUB inhibitors.
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28

Cullison, Andrew. "Three Millian Ways to Resolve Open Questions." Journal of Ethics and Social Philosophy 3, no. 1 (2017): 1–18. http://dx.doi.org/10.26556/jesp.v3i1.30.

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Millianism is a thesis in philosophy of language that the meaning of a proper name is simply its referent. Millianism faces certain puzzles called Frege's Puzzles. Some Millians defend the view by appealing to a metaphysics of belief that involves Ways of Believing. In the first part of this paper, I argue that ethical naturalists can adopt this Millian strategy to resist Moore’s Open Question argument. While this strategy of responding to the Open Question Argument has already appeared in the literature, I show that the Millian strategy can be easily extended to other versions of the Open Question Argument that are alleged to be stronger than the original formulation. The allegedly stronger versions of the Open Question Argument are not straightforwardly Frege's Puzzles, but they still have analogue versions that have been presented against Millianism. What the Ways Millian can say against those analogue versions can easily be applied to these other versions of the Open Question Argument.
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29

Hyvönen, Mervi T., Michael T. Howard, Christine B. Anderson та ін. "Divergent regulation of the key enzymes of polyamine metabolism by chiral α-methylated polyamine analogues". Biochemical Journal 422, № 2 (2009): 321–28. http://dx.doi.org/10.1042/bj20090737.

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The natural polyamines are ubiquitous multifunctional organic cations which play important roles in regulating cellular proliferation and survival. Here we present a novel approach to investigating polyamine functions by using optical isomers of MeSpd (α-methylspermidine) and Me2Spm (α,ω-bismethylspermine), metabolically stable functional mimetics of natural polyamines. We studied the ability of MeSpd and Me2Spm to alter the normal polyamine regulation pathways at the level of polyamine uptake and the major control mechanisms known to affect the key polyamine metabolic enzymes. These include: (i) ODC (ornithine decarboxylase), which catalyses the rate-limiting step of polyamine synthesis; (ii) ODC antizyme, an inhibitor of ODC and polyamine uptake; (iii) SSAT (spermidine/spermine N1-acetyltransferase), the major polyamine catabolic enzyme; and (iv) AdoMetDC (S-adenosyl-L-methionine decarboxylase), which is required for the conversion of putrescine into spermidine, and spermidine into spermine. We show that the stereoisomers differ in their cellular uptake and ability to downregulate ODC and AdoMetDC, and to induce SSAT. These effects are mediated by the ability of the enantiomers to induce +1 ribosomal frameshifting on ODC antizyme mRNA, to suppress the translation of AdoMetDC uORF (upstream open reading frame) and to regulate the alternative splicing of SSAT pre-mRNA. The unique effects of chiral polyamine analogues on polyamine metabolism may offer novel possibilities for studying the physiological functions, control mechanisms, and targets of the natural polyamines, as well as advance therapeutic drug development in cancer and other human health-related issues.
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30

Palian, Michael M., V. I. Boguslavsky, David F. O'Brie, and Robin Polt. "Glycopeptide-Membrane Interactions: Glycosyl Enkephalin Analogues Adopt Turn Conformations by NMR and CD in Amphipathic Media." Journal of the American Chemical Society 125, no. 19 (2003): 5823–31. http://dx.doi.org/10.1021/ja0268635.

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31

CHEN, Dawei, Frank J. RUZICKA, and Perry A. FREY. "A novel lysine 2,3-aminomutase encoded by the yodO gene of Bacillus subtilis: characterization and the observation of organic radical intermediates." Biochemical Journal 348, no. 3 (2000): 539–49. http://dx.doi.org/10.1042/bj3480539.

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The yodO gene product of Bacillus subtilis has been cloned and overexpressed in Escherichia coli and purified. The nucleotide sequence encodes a protein of 471 amino acids with a calculated molecular mass of 54071 Da. The translated amino acid sequence is more than 60% identical to that of the lysine 2,3-aminomutase from Clostridium subterminale SB4. Analytical HPLC gel-permeation chromatography leads to an estimate of an overall molecular mass of 224000±21000 Da, which corresponds to a tetrameric protein. The purified protein contains iron, sulphide and pyridoxal 5ʹ-phosphate (PLP) and displays an optical absorption band extending to 700 nm, suggesting the presence of an iron-sulphide cluster. After reductive incubation with L-cysteine anaerobically, the protein catalyses the transformation of L-lysine into β-lysine in the presence of S-adenosylmethionine (AdoMet) and sodium dithionite. The Km value for L-lysine is estimated to be 8.0±2.2 mM. The iron-sulphur centre is stable in air, allowing aerobic purification. EPR spectroscopy at 10 K of the purified enzyme revealed an EPR signal similar to that of the [4Fe-4S]3+ cluster observed in the clostridial lysine 2,3-aminomutase. Incubation with cysteine under anaerobic conditions converts the iron-sulphur centre into the EPR-silent [4Fe-4S]2+. Unlike the clostridial enzyme, the fully reduced [4Fe-4S]+ could not be characterized by further reduction with dithionite in the presence of AdoMet, although both dithionite and AdoMet were required to activate the enzyme. Upon addition of L-lysine, dithionite and AdoMet to the reduced enzyme and freezing the solution to 77 K, the EPR spectrum revealed the presence of an organic free-radical signal (g = 2.0023), which displayed multiple hyperfine transitions very similar to the spectrum of the β-lysine-related radical in the mechanism of the clostridial lysine 2,3-aminomutase. Experiments with isotopically substituted L-lysine and lysine analogues verified the association of spin density with the carbon skeleton of lysine. The data indicate that the protein encoded by the yodO gene of B. subtilis is a novel lysine 2,3-aminomutase. The E. coli homologue of clostridial lysine 2,3-aminomutase was also expressed in E. coli and purified. This protein contained iron and sulphide but not PLP, it did not display lysine 2,3-aminomutase activity, and addition of PLP did not induce 2,3-aminomutase activity.
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32

Salin, Mikko, Evangelia G. Kapetaniou, Matti Vaismaa, et al. "Crystallographic binding studies with an engineered monomeric variant of triosephosphate isomerase." Acta Crystallographica Section D Biological Crystallography 66, no. 8 (2010): 934–44. http://dx.doi.org/10.1107/s0907444910025710.

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Crystallographic binding studies have been carried out to probe the active-site binding properties of a monomeric variant (A-TIM) of triosephosphate isomerase (TIM). These binding studies are part of a structure-based directed-evolution project aimed towards changing the substrate specificity of monomeric TIM and are therefore aimed at finding binders which are substrate-like molecules. A-TIM has a modified more extended binding pocket between loop-7 and loop-8 compared with wild-type TIM. The A-TIM crystals were grown in the presence of citrate, which is bound in the active site of each of the two molecules in the asymmetric unit. In this complex, the active-site loops loop-6 and loop-7 adopt the closed conformation, similar to that observed in liganded wild-type TIM. Extensive crystal-soaking protocols have been developed to flush the bound citrate out of the active-site pocket of both molecules and the crystal structure shows that the unliganded open conformation of the A-TIM active site is the same as in unliganded wild-type TIM. It is also shown that sulfonate compounds corresponding to the transition-state analogue 2-phosphoglycolate bind in the active site, which has a closed conformation. It is also shown that the new binding pocket of A-TIM can bind 3-phosphoglycerate (3PGA; an analogue of a C4-sugar phosphate) and 4-phospho-D-erythronohydroxamic acid (4PEH; an analogue of a C5-sugar phosphate). Therefore, these studies have provided a rationale for starting directed-evolution experiments aimed at generating the catalytic properties of a C5-sugar phosphate isomerase on the A-TIM framework.
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33

Baumgartner, Benjamin, and Riccardo Gatto. "A Bootstrap Test for the Probability of Ruin in the Compound Poisson Risk Process." ASTIN Bulletin 40, no. 1 (2010): 241–55. http://dx.doi.org/10.2143/ast.40.1.2049227.

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AbstractIn this article we propose a bootstrap test for the probability of ruin in the compound Poisson risk process. We adopt the P-value approach, which leads to a more complete assessment of the underlying risk than the probability of ruin alone. We provide second-order accurate P-values for this testing problem and consider both parametric and nonparametric estimators of the individual claim amount distribution. Simulation studies show that the suggested bootstrap P-values are very accurate and outperform their analogues based on the asymptotic normal approximation.
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34

Bessenbacher, Christian, and Wolfgang Kaim. "Elektronenreiche Olefine, 3 / Electron Rich Olefins, 3." Zeitschrift für Naturforschung B 44, no. 5 (1989): 511–18. http://dx.doi.org/10.1515/znb-1989-0502.

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Exhaustive reductive silylation of 2-trimethylsilyl-1,2,3-triazole (1) using Me,SiCl/K yields the new E-1,1,4,4-tetrakis(trimethylsilyl)-l,4-diazabutene(2) (4) as final product together with N(SiMe3)3. Initial reductive 1,4-addition to 1 leads to formation of 1.2.3-tris(trimethylsilyl)-1,2,3-triazoline(4) (2) as an intermediate which is rapidly reduced and silylated further to give the butene 4. Partial π overlap within the five-membered ring 2 containing 8 π electrons and three neighbouring unshared electron pairs is evident from NMR shifts and electron transfer reaction with TCNE. Photoelectron spectroscopy of 4 and the lability of its radical cation 4+. as studied by ESR show that this system cannot adopt a planar conformation in contrast to the tetrazene(2) analogue.
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35

Skołuba, Dominika, Dariusz Sobolewski, Adam Prahl, and Edyta Proniewicz. "Interaction of Bradykinin and B2Bradykinin Receptor Antagonists with Colloidal Au Surface Explored by Surface-Enhanced Raman Scattering." Journal of Spectroscopy 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/619373.

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Bradykinin (BK), an endogenous peptide hormone, which is involved in a number of physiological and pathophysiological processes, and the potent B2bradykinin receptor antagonists, [D-Arg0,Hyp3,Thi5,8,L-Pip7]BK, Aaa[D-Arg0,Hyp3,Thi5,8,L-Pip7]BK, [D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK, and Aaa[D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK, were deposited onto colloidal Au particles of 20 nm size. Interaction of these molecules with colloidal Au surface was explored by surface-enhanced Raman scattering (SERS). Briefly, it was shown that BK adsorbs on the Au surface mainly through the Phe5/Phe8residues. In case of the BK specifically modified analogues mainly the Pip and Thi rings are involved in the interaction process; however, Pip and Thi adopt slightly different orientation with respect to Au for each of the analogues. In addition, the lack of the Aaa vibrations, together with the enhancement of the Thi, Pip, or Phe modes, emphasizes the importance of theC-terminus in the interaction with the Au surface.
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36

Wu, Leiming, Zhongjian Xie, Lu Lu, et al. "Few-Layer Tin Sulfide: A Promising Black-Phosphorus-Analogue 2D Material with Exceptionally Large Nonlinear Optical Response, High Stability, and Applications in All-Optical Switching and Wavelength Conversion." Advanced Optical Materials 6, no. 2 (2017): 1700985. http://dx.doi.org/10.1002/adom.201700985.

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37

Osowole, A. A. "Syntheses and Characterization of Some Tetradentate Schiff-Base Complexes and Their Heteroleptic Analogues." E-Journal of Chemistry 5, no. 1 (2008): 130–35. http://dx.doi.org/10.1155/2008/654054.

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VO(IV), Ni(II) and Cu(II) complexes of the asymmetric Schiff base [(HOC6H3(OCH3)C(C6H5):N(CH2CH2)N:C(CH3)CH:C(C6H5)OH)], and their heteroleptic analogues with triphenyl phosphine and 2,2’-bipyridine have been synthesized and characterized by elemental analyses, conductance, magnetic, infrared and electronic spectral measurements. The ligand is tetradentate coordinatingviathe imine N and enolic O atoms. The Ni(II) and Cu(II) complexes adopt a four coordinate square planar geometry, the VO(IV) complex is five coordinate square-pyramidal and the heteroleptic complexes are 6-coordinate, octahedral. The assignment of geometry is collaborated by magnetic moments and electronic spectra measurements. The compounds are non-electrolyte in nitromethane and are magnetically dilute.
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38

Wu, Dan, Na Qin, Qi-Kui Liu, Jian-Ping Ma, and Yu-Bin Dong. "The structures of three Hg2X4L2macrocycles {X= Cl, Br and I, andL= 1,2-bis[4-(pyridin-3-yl)phenoxy]ethane} assembled from ether-bridged dipyridyl ligands." Acta Crystallographica Section C Crystal Structure Communications 68, no. 6 (2012): m156—m160. http://dx.doi.org/10.1107/s0108270112019075.

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The new ether-bridged dipyridyl ligand 1,2-bis[4-(pyridin-3-yl)phenoxy]ethane (L) has been used to synthesize three isostructural centrosymmetric binuclear HgIImacrocycles, namely bis{μ-1,2-bis[4-(pyridin-3-yl)phenoxy]ethane-κ2N:N′}bis[dichloridomercury(II)], [Hg2Cl4(C24H20N2O2)2], and the bromido, [Hg2Br4(C24H20N2O2)2], and iodido, [Hg2I4(C24H20N2O2)2], analogues. The Hg atoms adopt a highly distorted tetrahedral coordination environment consisting of two halides and two pyridineN-donor atoms from two bridging ligands. In the solid state, the macrocycles form two-dimensional sheets in thebcplane through noncovalent Hg...XandX...X(X= Cl, Br and I) interactions.
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39

Guijarro Lasheras, Rodrigo. "Graphic analogies in the imitation of music in literature." Semiotica 2020, no. 236-237 (2020): 103–22. http://dx.doi.org/10.1515/sem-2017-0107.

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AbstractMusic may have a strong influence on literature. Many novels have reflected this by thematizing music in many different ways. However, this engagement can also adopt the form of an imitation or a formal presence that does not actually require the text to say anything about music. This paper aims to explore some aspects of musical imitation in literature that have not been analyzed in depth. Departing from the approach developed by Werner Wolf, I propose a distinction between imitating and imitated elements that applies to any case of study. Furthermore, at the core of this article, I advocate for a fourth dimension that the imitation of music in literature may have and that should be added to word music, formal and structural analogies, and imaginary content analogies. I call this fourth category “graphic analogies.” It implies an imitation whose imitating element is the graphic, written aspect of the linguistic signifier. Finally, this leads to the idea that, in the case of the imitation of music in literature, there is not a necessary correlation between imitating and imitated elements.
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40

Fennell, T., S. T. Bramwell, and M. A. Green. "Structural and magnetic characterization of Ho3SbO7 and Dy3SbO7." Canadian Journal of Physics 79, no. 11-12 (2001): 1415–19. http://dx.doi.org/10.1139/p01-106.

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We present an experimental investigation of the structural and magnetic properties of Ho3SbO7 and Dy3SbO7. These compounds adopt the Y3TaO7 structure, space group C2221. The magnetic rare-earth ions occupy an intricate lattice related to the pyrochlore lattice that occurs in Ho2Ti2O7 and Dy2Ti2O7. The crystal structure of Ho3SbO7 is determined by Rietveld refinement of the powder X-ray diffraction pattern at ambient temperature, and that of the Dy analogue is inferred to be similar. Magnetic susceptibility measurements show that Ho3SbO7 and Dy3SbO7 have negative Curie–Weiss temperatures: –8.4 K (Ho) and –9.2 K (Dy). Magnetic transitions have been detected at 2.0 K (Ho) and 3.0 K (Dy). We discuss the results in terms of the ``dipolar spin ice model'' that has been used to describe Ho2Ti2O7 and Dy2Ti2O7. PACS Nos.: 75.25+z, 75.50Ee, 61.10Nz
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41

Ashwell, G. J., та G. A. N. Paxton. "Multifunctional Properties of (Z)-β-(N-Hexadecyl-4-quinolinium)-α-cyano-4-styryldicyanomethanide: a Molecular Rectifier, Optically Non-Linear Dye, and Ammonia Sensor". Australian Journal of Chemistry 55, № 3 (2002): 199. http://dx.doi.org/10.1071/ch01182.

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The zwitterionic dye, Z-β-(N-hexadecyl-4-quinolinium)-α-cyano-4-styryldicyanomethanide (C16H33-Q3CNQ), forms dimeric solution aggregates, which are probably centric, but adopt a non-centrosymmetric arrangement at the air/water interface. When spread from dilute solution, e.g. 3 × 10-5 M in CH2Cl2, the resultant Langmuir-Blodgett (LB) films are purple, λmax 563 ± 3 nm. They have an optimum effective second-order non-linear optical susceptibility of 75 pm V-1 at 1.064 μm and, when sandwiched between gold electrodes, exhibit asymmetric current-voltage curves, characteristic of molecular rectification. In contrast, when spread at slightly higher concentrations (e.g. 10-4 M), the resultant LB films are polymorphic and have absorption maxima at 563 and 670 nm, the latter being characteristic of the benzyl analogue (φ-CH2-Q3CNQ). Its films are turquoise, λmax 668 ± 3 nm, and both molecular rectification and second-harmonic generation are inhibited. Thus, the red-shifted charge-transfer band probably reflects an altered alignment whereby the molecules adopt a centric antiparallel arrangement within the monolayer. The zwitterionic films readily protonate, with bleaching, and may be used to sense ammonia at concentrations of ca. 1 ppm by monitoring changes in the surface plasmon resonance.
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42

Shneine, Jewad, Marc Voswinkel, Matthias Federwisch, and Axel Wollmer. "Enhancing the T R Transition of Insulin by Helix-Promoting Sequence Modifications at the N-Terminal B-Chain." Biological Chemistry 381, no. 2 (2000): 127–33. http://dx.doi.org/10.1515/bc.2000.018.

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Abstract Structurally, the T→R transition of insulin mainly consists of a rearrangement of the N-terminal B-chain (residues B1–B8) from extended to helical in one or both of the trimers of the hexamer. The dependence of the transition on the nature of the ligands inducing it, such as inorganic anions or phenolic compounds, as well as of the metal ions complexing the hexamer, has been the subject of extensive investigations. This study explores the effect of helix-enhancing modifications of the N-terminal B-chain sequence where the transition actually occurs, with special emphasis on N-capping. In total 15 different analogues were prepared by semisynthesis. 80% of the hexamers of the most successful analogues with zinc were found to adopt the T3R3 state in the absence of any transforming ligands, as compared to only 4% of wild-type insulin. Transformation with SCN− ions can exceed the T3R3 state where it stops in the case of wild-type insulin. Full transformation to the R6 state can be achieved by only one-tenth the phenol concentration required for wild-type insulin, i. e. almost at the stoichiometric ratio of 6 phenols per hexamer.
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43

Virgilio, Antonella, Veronica Esposito, Annalisa Pecoraro, et al. "Structural properties and anticoagulant/cytotoxic activities of heterochiral enantiomeric thrombin binding aptamer (TBA) derivatives." Nucleic Acids Research 48, no. 22 (2020): 12556–65. http://dx.doi.org/10.1093/nar/gkaa1109.

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Abstract The thrombin binding aptamer (TBA) possesses promising antiproliferative properties. However, its development as an anticancer agent is drastically impaired by its concomitant anticoagulant activity. Therefore, suitable chemical modifications in the TBA sequence would be required in order to preserve its antiproliferative over anticoagulant activity. In this paper, we report structural investigations, based on circular dichroism (CD) and nuclear magnetic resonance spectroscopy (NMR), and biological evaluation of four pairs of enantiomeric heterochiral TBA analogues. The four TBA derivatives of the d-series are composed by d-residues except for one l-thymidine in the small TT loops, while their four enantiomers are composed by l-residues except for one d-thymidine in the same TT loop region. Apart from the left-handedness for the l-series TBA derivatives, CD and NMR measurements have shown that all TBA analogues are able to adopt the antiparallel, monomolecular, ‘chair-like’ G-quadruplex structure characteristic of the natural D-TBA. However, although all eight TBA derivatives are endowed with remarkable cytotoxic activities against colon and lung cancer cell lines, only TBA derivatives of the l-series show no anticoagulant activity and are considerably resistant in biological environments.
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44

Kubba, Haytham. "How uncomfortable are the various positions recommended for the instillation of nose drops?" Journal of Laryngology & Otology 113, no. 4 (1999): 326–28. http://dx.doi.org/10.1017/s0022215100143890.

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AbstractNose drops are widely used in the topical treatment of nasal disorders. Their efficacy has previously been shown to depend on the position of the head adopted during instillation. All three of the commonly recommended head positions (head back, praying-to-Mecca, Mygind's) are uncomfortable, and this may affect patient compliance. As yet, no assessment has been made of the discomfort encountered by patients. Twenty adults from a general otolaryngology clinic were asked to adopt each of three positions and then rate the discomfort experienced on a 10 cm visual analogue scale. The results show that although Mygind's position is well tolerated, the praying-to-Mecca position was significantly more uncomfortable than any other. In the absence of any evidence that the praying-to-Mecca position is clinically more efficacious than Mygind's, it seems inappropriate to continue to advocate its use.
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45

Vangelista, Luca, Massimiliano Secchi, Xiaowen Liu, et al. "Engineering of Lactobacillus jensenii To Secrete RANTES and a CCR5 Antagonist Analogue as Live HIV-1 Blockers." Antimicrobial Agents and Chemotherapy 54, no. 7 (2010): 2994–3001. http://dx.doi.org/10.1128/aac.01492-09.

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ABSTRACT The development of effective microbicides for the prevention of HIV-1 sexual transmission represents a primary goal for the control of AIDS epidemics worldwide. A promising strategy is the use of bacteria belonging to the vaginal microbiota as live microbicides for the topical production of HIV-1 inhibitors. We have engineered a human vaginal isolate of Lactobacillus jensenii to secrete the anti-HIV-1 chemokine RANTES, as well as C1C5 RANTES, a mutated analogue that acts as a CCR5 antagonist and therefore is devoid of proinflammatory activity. Full-length wild-type RANTES and C1C5 RANTES secreted by L. jensenii were purified to homogeneity and shown to adopt a correctly folded conformation. Both RANTES variants were shown to inhibit HIV-1 infection in CD4+ T cells and macrophages, displaying strong activity against HIV-1 isolates of different genetic subtypes. This work provides proof of principle for the use of L. jensenii-produced C1C5 RANTES to block HIV-1 infection of CD4+ T cells and macrophages, setting the basis for the development of a live anti-HIV-1 microbicide targeting CCR5 in an antagonistic manner.
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46

Hambley, TW, GA Lawrance, DF Sangster, and CB Ward. "Characterization, Redox Properties and Pulse-Radiolysis Study of Dichloro-(Tetraazacyclotetradecane)Manganese(III) Complexes, and X-Ray Crystal-Structure of the meso-5,7,7,12,14,14-Hexamethyl-1,4,8,11-Tetraazacyclotetradecane Complex." Australian Journal of Chemistry 40, no. 5 (1987): 883. http://dx.doi.org/10.1071/ch9870883.

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The complexes [Mn ( mac )Cl2]+ [ mac = 1,4,8,1l-tetraazacyclotetradecane (cyclam), meso and rac-5,7,7,12,14,14-hexamethylcyclam ( teta and tetb respectively)] have been prepared. The trans-[ Mn ( teta )Cl2] Cl.3H2O complex crystallizes in the monoclinic space group P21 /c, Z 2, a 8.4006(8), b 12.465(2), c 11 .659(2) �, β 103.20(1)�. The geometry about the manganese(III) is close to octahedral with the macrocycle coordinated to four equatorial sites ( Mn -N 2.043(2), 2.074(2) �) and chlorides in trans axial sites (Mn -Cl 2.549(1) �. Since electronic spectra of the cyclam and teta complexes are similar, the ions should exist in similar geometries; however, the tet b analogue is spectroscopically unique, and the complex may adopt a different geometry. All complexes in water exhibit quasi-reversible one-electron couples near O V at a mercury electrode; irreversible reductions of manganese(II) are also observed before the solvent limit near -1.5 V for the teta and tet b complexes. No metal-centred oxidation waves are seen before the solvent limit (c.+ 1 V) at a platinum electrode. However, pulse radiolytic oxidation (with OH) of all complexes is observed with formation kf > 109 dm3mol-1 s-1; apparently d3 manganese(IV) monomers with electronic spectra qualitatively similar to d3 chromium(III) complexes are formed. Decay of these intermediates is first-order, with all kd ≥ 5×103 s-1, but varying with the macrocyclic ligand present. Alkyl substitution on the cyclam stabilizes the manganese(IV) oxidation state, the intermediate cyclam complex decaying 25 times faster than the teta analogue. The final decay product appears to be MnO2, and rate-determining ligand loss is presumed.
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47

Danylevskyi, Andriy, and Yuliya Danylevska. "CONCERNING THE COMPLIANCE OF THE LEGISLATION OF UKRAINE ON CRIMINAL LIABILITY IN THE SPHERE OF ILLEGAL DRUG TRAFFICKING WITH INTERNATIONAL REGULATORY LEGAL ACTS." Law Journal of Donbass 73, no. 4 (2020): 95–102. http://dx.doi.org/10.32366/2523-4269-2020-73-4-95-102.

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The public danger of illegal drug trafficking, drug addiction and related phenomena is obvious; therefore the world community is making significant efforts to counter these phenomena, because only through joint efforts it is possible to ensure an effective counteraction to drug trafficking. For this purpose, states adopt a significant number of international normative legal acts. The issues of countering the illegal drug trafficking, psychotropic substances, their analogues and precursors are considered both within the framework of general documents on combating crime, and in special acts. Taking into account the European integration course of Ukraine, the expansion of international cooperation in the sphere of combating the illegal drug trafficking drugs, psychotropic substances, their analogues and precursors, the following issues should be marked as ones of great importance: observance by Ukraine of its international legal obligations; integration into the world system of counteracting drug trafficking; bringing national legislation in line with the provisions of international regulatory legal acts. This article is devoted to the outlined questions. In particular, the provisions of the national legislation in the sphere of illegal drug trafficking, psychotropic substances, their analogues and precursors are analyzed, and the compliance of domestic norms with international regulatory legal acts in the sphere of combating illegal drug trafficking is concluded. The classification of international regulatory legal acts in the sphere of illegal drug trafficking in dependence to the authority that issued them is given. On the basis of the conducted analysis, the author suggests ways to further improvement of the domestic criminal legislation in the sphere of combating drug trafficking. In particular, it is proposed to criminalize the sowing and cultivation of any kind of narcotic drugs, as well as to partially revise the punishment for certain drug crimes.
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48

Kilovaty, Ido. "The Elephant in the Room: Coercion." AJIL Unbound 113 (2019): 87–91. http://dx.doi.org/10.1017/aju.2019.10.

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Dan Efrony and Yuval Shany's article offers some critically important observations on the reception of the Tallinn Manual 2.0 by states, as well as subsequent state practice and opinio juris with regard to the international use of cyber operations. Based on their case studies, Efrony and Shany conclude that states have largely been reluctant to adopt fully the norms, premises, and analogies offered by the Tallinn Manual. The authors argue that there is a “deep uncertainty about the treatment of cyberspace as just another physical space, like land, air, or sea—over which states may exercise sovereignty or control.” The authors further explain that there is an “uneasy fit” between traditional international law regarding internal and external state power, and the regulation of a unterritorial cyberspace. In other words, cyberspace is a sui generis domain, such that analogies to physical-space domains are often ill-suited, and at times doomed to failure.
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Markovski, Mishel R., Oleg I. Siidra, Dmitri O. Charkin та Vasili Yu Grishaev. "Layered calcium hydrogen selenite chlorides Ca(HSeO3)Cl and Ca(HSeO3)Cl(H2O), the first halides obtained in СaCl2–H2SeO3–H2O system". Zeitschrift für Kristallographie - Crystalline Materials 235, № 10 (2020): 439–43. http://dx.doi.org/10.1515/zkri-2020-0054.

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AbstractSynthesis, crystal structures and IR spectra of the first representatives of calcium hydrogen selenite halides are reported. Colourless prismatic crystals of calcium hydrogen selenite chloride Ca(HSeO3)Cl and corresponding hydrated analogue Ca(HSeO3)Cl(H2O) were produced upon evaporation of aqueous solutions. Ca(HSeO3)Cl is monoclinic, P21/c, a = 7.0031(11) Å, b = 7.7336(12) Å, c = 8.5024(13) Å, β = 109.889(3)°, V = 433.02(12) Å3, R1 = 0.039. Ca(HSeO3)Cl(H2O) is orthorhombic, Pbca, a = 6.222(4) Å, b = 10.413(7) Å, c = 16.875(10) Å, V = 1093.3 (12) Å3, R1 = 0.041. Ca(HSeO3)Cl and Ca(HSeO3)Cl(H2O) represent new structure types. In both structures, Ca2+ cations adopt mixed-ligand environments formed by oxygen atoms of hydrogen selenite anions (and water molecules for Ca(HSeO3)Cl(H2O)) and chloride ions. Both structures are layered. The crystal structure of Ca(HSeO3)Cl(H2O) demonstrates a rare phenomenon of hydrogen-bonded assembly of water and chloride in the interlayer space.
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CROWLEY, Peter B., David M. HUNTER, Katsuko SATO, William McFARLANE, and Christopher DENNISON. "The parsley plastocyanin-turnip cytochrome f complex: a structurally distorted but kinetically functional acidic patch." Biochemical Journal 378, no. 1 (2004): 45–51. http://dx.doi.org/10.1042/bj20031423.

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Abstract:
In general, inter-protein electron transfer proceeds via the formation of transient complexes. The initial stage of the interaction between plastocyanin (PCu) and cytochrome f (cyt f) from plants is mediated by complementary electrostatics. Given the diffuse nature of its acidic patch, parsley PCu is an atypical example of a plant PCu. The interaction of this PCu with turnip cyt f was investigated by stopped-flow kinetics, NMR spectroscopy and protein-docking simulations. We show that, despite the altered acidic patch, parsley PCu is as efficient as spinach PCu in accepting electrons from cyt f, over the physiological range of ionic strength. At high ionic strength, the rate constant for the reaction of cyt f with parsley PCu is twice that of the spinach protein. This difference in reactivity is attributed to variations in the hydrophobic patch of parsley PCu. The results of NMR studies and protein-docking simulations indicate that parsley PCu and its spinach analogue adopt different orientations in their complexes with cyt f.
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