6-Azauracil

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Jan Slouka - One of the best experts on this subject based on the ideXlab platform.

Jan Hlaváč - One of the best experts on this subject based on the ideXlab platform.

Xiaojun Liu - One of the best experts on this subject based on the ideXlab platform.

  • Ultrafast Excited-State Dynamics of 6-Azauracil Studied by Femtosecond Transient Absorption Spectroscopy
    The journal of physical chemistry. A, 2015
    Co-Authors: Xinzhong Hua, Linqiang Hua, Xiaojun Liu
    Abstract:

    The excited-state dynamics of 6-Azauracil in different solvents have been studied using femtosecond transient absorption spectroscopy. The molecule is populated to the S-2 state with a pump pulse at 264 nm. Broad-band white light continuum which covers from 320 to 600 nm is used as the probe. With a global fitting analysis of the measured transient spectra, three decay time constants, i.e., 1000 ps, are directly obtained in the solvent of acetonitrile. These newly observed lifetime constants are important in clarifying its decay dynamics as well as in providing a criterion for the ultrafast dynamics simulations in 6-Azauracil using quantum chemical theories. In combination with previous theoretical works, the main decay channel is proposed: the initially populated S-2 decays to S-1 through internal conversion in 1000 ps component is due to the decay of the T-1 state. A comparison of the excited-state dynamics in different solvents reveals that the decay from S, to T-1 shows a clear dependence on the polarity of the solvents. With higher polarity, the S-1 excited state decays faster. This observation is in line with the prediction by Etinski et al. [Phys. Chem. Chem. Phys. 2010, 12, 15665-15671], where a blue-shift of the T-1 state potential energy surface leading to an increase of the intersystem crossing rate was proposed. With the new information obtained in the present measurement, a clearer picture of the decay dynamics of 6-Azauracil on the S-2 excited state is provided.

  • Ultrafast Excited-State Dynamics of 6‑Azauracil Studied by Femtosecond Transient Absorption Spectroscopy
    2015
    Co-Authors: Xinzhong Hua, Linqiang Hua, Xiaojun Liu
    Abstract:

    The excited-state dynamics of 6-Azauracil in different solvents have been studied using femtosecond transient absorption spectroscopy. The molecule is populated to the S2 state with a pump pulse at 264 nm. Broad-band white light continuum which covers from 320 to 600 nm is used as the probe. With a global fitting analysis of the measured transient spectra, three decay time constants, i.e., 1000 ps, are directly obtained in the solvent of acetonitrile. These newly observed lifetime constants are important in clarifying its decay dynamics as well as in providing a criterion for the ultrafast dynamics simulations in 6-Azauracil using quantum chemical theories. In combination with previous theoretical works, the main decay channel is proposed: the initially populated S2 decays to S1 through internal conversion in 1000 ps component is due to the decay of the T1 state. A comparison of the excited-state dynamics in different solvents reveals that the decay from S1 to T1 shows a clear dependence on the polarity of the solvents. With higher polarity, the S1 excited state decays faster. This observation is in line with the prediction by Etinski et al. [Phys. Chem. Chem. Phys. 2010, 12, 15665−15671], where a blue-shift of the T1 state potential energy surface leading to an increase of the intersystem crossing rate was proposed. With the new information obtained in the present measurement, a clearer picture of the decay dynamics of 6-Azauracil on the S2 excited state is provided

Facultas Rerum - One of the best experts on this subject based on the ideXlab platform.

  • Chemistry of 1-aryl-6-Azauracil-5-carbonitriles
    2004
    Co-Authors: Facultas Rerum, Naturalium Chemica
    Abstract:

    Although 6-Azauracil-5-carbonitriles and their 1-aryl derivatives represent quite large group of 6-Azauracil derivatives, the review of their chemistry has not been published yet. This communication gives complete review of the mentioned compounds. The literature data are complete until 2004

  • 1-ARYL-6-AzauracilS XLI # SYNTHESIS AND REACTIVITY OF 1-(3,5-DINITROPHENYL)-6-Azauracil-5-CARBONITRILE
    2001
    Co-Authors: Facultas Rerum, Naturalium Chemica, Petr Bilek, Jan Slouka
    Abstract:

    Diazotization of 3,5-dinitroaniline either in acetic acid or nitrosylsulphuric acid afforded diazonium salt that after coupling either with ethyl cyanoacetylcarbamate or diethyl malonylbiscarbamate afforded corresponding hydrazones (2a) or (2b) respectively. After cyclization of (2a) in xylene we received 3,5-dinitrophenyl-6-Azauracil derivative (3a). This derivative underwent hydrolytic splitting of the triazine cycle by boiling in water pyridine solution resulting in 3,5-dinitrophenylhydrazonocyanoacetamide (4a) that was impossible to obtain directly by coupling reaction. Key words: Coupling reactions of 3,5-dinitrobenzenediazonium salts, splittin

  • SYNTHESIS OF 5-(M-TOLYL)-6-Azauracil AND SOME OF ITS DERIVATIVES
    2000
    Co-Authors: Facultas Rerum, Naturalium Chemica, Jan Hlaváč, Jan Slouka, Pavel Hradil, Ar N
    Abstract:

    7-Methylisatin (I) was converted to appropriate semicarbazone (II). Its alkaline recyclization afforded 5-(2-amino-3-methyl)-6-Azauracil (III). Its diazotation and subsequent reductive elimination of diazonium group led to the 5-(m-tolyl)-6-Azauracil (VI). Appropriate hydrazone (V) was prepared by coupling of diazotated amine III with ethyl cyanoacetylcarbamate. After reaction with bicarbonate this compound was converted to 1-[2-(6-Azauracil-5-yl)-6-methylphenyl]-6-Azauracil-5-carbonitrile (VII). Cyclization of aminoderivative III afforded 3,5-dihydro-5H-6-methyl-[1,2,4]triazino[5,6-b]indole-3-one (VII) Key words: 5-aryl-6-Azauracils, twocyclic 6-Azauracils, [1,2,4]-triazino[5,6-b]indol

  • 1-ARYL-6-AzauracilS XL* SYNTHESIS OF SOME 1-(1-PHENYL-3-PYRAZOLYL)- DERIVATIVES
    2000
    Co-Authors: Facultas Rerum, Naturalium Chemica, Petr Cankař, Jan Slouka
    Abstract:

    The appropriate hydrazone I was obtained by the diazotation of 1-phenyl-3aminopyrazole and by the following coupling reaction of formed diazonium salt with ethyl cyanoacetyl carbamate. The cyclization of this hydrazone does not undergo to the appropriate derivative pyrazolo[5,1-c][1,2,4]triazine, but both the thermal and the alkaline cyclization undergoes to 1-(1-phenyl-3-pyrazolyl)-6-Azauracil-5-carbonitrile II. This compound serves as a starting material for the appropriate acid III, amidoxime IV and 1-(1-phenyl-3-pyrazolyl)-5-(5-methyl-[1,2,4]oxadiazol-3-yl)-6azauracile V. Key words: 1,2,4-triazine, 1,5-disubstituted 6-Azauracils, 1,3-disubstituted pyrazole

Shunji Natori - One of the best experts on this subject based on the ideXlab platform.

  • Transcription Elongation Factor S-II Confers Yeast Resistance to 6-Azauracil by Enhancing Expression of the SSM1 Gene
    The Journal of biological chemistry, 2000
    Co-Authors: Makoto Shimoaraiso, Toshiyuki Nakanishi, Takeo Kubo, Shunji Natori
    Abstract:

    Abstract Loss of function of S-II makes yeast sensitive to 6-Azauracil. Here, we identified a multi-copy suppressor gene of this phenotype, termed SSM1 (suppressor of 6-Azauracil sensitivity of the S-II null mutant 1), that encodes a novel protein consisting of 280 amino acid residues. Although both theSSM1 null mutant and the S-II/SSM1 double null mutant were viable under normal growth conditions, they resembled theS-II null mutant in being sensitive to 6-Azauracil. Expression of the SSM1 gene was found to be repressed in theS-II null mutant but was restored by overexpression of chimeric S-II molecules that were able to stimulate transcription elongation by RNA polymerase II in vitro. Furthermore, we identified two transcription arrest sites within the transcription unit of the SSM1 gene in vitro that could be relieved by S-II. These results indicate that S-II confers yeast resistance to 6-Azauracil by stimulating transcription elongation of the SSM1 gene.

  • Structure-function relationship of yeast S-II in terms of stimulation of RNA polymerase II, arrest relief, and suppression of 6-Azauracil sensitivity.
    The Journal of biological chemistry, 1995
    Co-Authors: Toshiyuki Nakanishi, Makoto Shimoaraiso, Takeo Kubo, Shunji Natori
    Abstract:

    Abstract The yeast S-II null mutant is viable, but the mutation induces sensitivity to 6-Azauracil. To examine whether the region needed for stimulation of RNA polymerase II and that for suppression of 6-Azauracil sensitivity in the S-II molecule could be separated, we constructed various deletion mutants of S-II and expressed them in the null mutant using the GAL1 promoter to see if the mutant proteins suppressed 6-Azauracil sensitivity. We also expressed these constructs in Escherichia coli, purified the mutant proteins to homogeneity, and examined if they stimulated RNA polymerase II. We found that a mutant protein lacking the first 147 amino acid residues suppressed 6-Azauracil sensitivity but that removal of 2 additional residues completely abolished the suppression. A mutant protein lacking the first 141 residues had activity to stimulate RNA polymerase II, whereas removal of 10 additional residues completely abolished this activity. We also examined arrest-relief activity of these mutant proteins and found that there is a good correlation between RNA polymerase II-stimulating activity and arrest-relief activity. Therefore, at least the last 168 residues of S-II are sufficient for expressing these three activities.