Science.gov

Sample records for acetate methyl formate

  1. DISCOVERY OF METHYL ACETATE AND GAUCHE ETHYL FORMATE IN ORION

    SciTech Connect

    Tercero, B.; Cernicharo, J.; Lopez, A.; Caro, G. M. Munoz; Kleiner, I.; Nguyen, H. V. L. E-mail: jcernicharo@cab.inta-csic.es E-mail: munozcg@cab.inta-csic.es E-mail: nguyen@pc.rwth-aachen.de

    2013-06-10

    We report on the discovery of methyl acetate, CH{sub 3}COOCH{sub 3}, through the detection of a large number of rotational lines from each one of the spin states of the molecule: AA species (A{sub 1} or A{sub 2}), EA species (E{sub 1}), AE species (E{sub 2}), and EE species (E{sub 3} or E{sub 4}). We also report, for the first time in space, the detection of the gauche conformer of ethyl formate, CH{sub 3}CH{sub 2}OCOH, in the same source. The trans conformer is also detected for the first time outside the Galactic center source SgrB2. From the derived velocity of the emission of methyl acetate, we conclude that it arises mainly from the compact ridge region with a total column density of (4.2 {+-} 0.5) Multiplication-Sign 10{sup 15} cm{sup -2}. The derived rotational temperature is 150 K. The column density for each conformer of ethyl formate, trans and gauche, is (4.5 {+-} 1.0) Multiplication-Sign 10{sup 14} cm{sup -2}. Their abundance ratio indicates a kinetic temperature of 135 K for the emitting gas and suggests that gas-phase reactions could participate efficiently in the formation of both conformers in addition to cold ice mantle reactions on the surface of dust grains.

  2. Adsorption and Thermal Processing of Glycolaldehyde, Methyl Formate, and Acetic Acid on Graphite at 20 K.

    PubMed

    Burke, Daren J; Puletti, Fabrizio; Woods, Paul M; Viti, Serena; Slater, Ben; Brown, Wendy A

    2015-07-01

    We present the first detailed comparative study of the adsorption and thermal processing of the three astrophysically important C2O2H4 isomers glycolaldehyde, methyl formate, and acetic acid adsorbed on a graphitic grain analogue at 20 K. The ability of the individual molecule to form intermolecular hydrogen bonds is extremely important, dictating the growth modes of the ice on the surface and the measured desorption energies. Methyl formate forms only weak intermolecular bonds and hence wets the graphite surface, forming monolayer, bilayer, and multilayer ices, with the multilayer having a desorption energy of 35 kJ mol(-1). In contrast, glycolaldehyde and acetic acid dewet the surface, forming clusters even at the very lowest coverages. The strength of the intermolecular hydrogen bonding for glycolaldehyde and acetic acid is reflected in their desorption energies (46.8 and 55 kJ mol(-1), respectively), which are comparable to those measured for other hydrogen-bonded species such as water. Infrared spectra show that all three isomers undergo structural changes as a result of thermal processing. In the case of acetic acid and glycolaldehyde, this can be assigned to the formation of well-ordered, crystalline, structures where the molecules form chains of hydrogen-bonded moieties. The data reported here are of relevance to astrochemical studies of hot cores and star-forming regions and can be used to model desorption from interstellar ices during the warm up phase with particular importance for complex organic molecules. PMID:26057183

  3. Glycolaldehyde, methyl formate and acetic acid adsorption and thermal desorption from interstellar ices

    NASA Astrophysics Data System (ADS)

    Burke, Daren J.; Puletti, Fabrizio; Brown, Wendy A.; Woods, Paul M.; Viti, Serena; Slater, Ben

    2015-02-01

    We have undertaken a detailed investigation of the adsorption, desorption and thermal processing of the astrobiologically significant isomers glycolaldehyde, acetic acid and methyl formate. Here, we present the results of laboratory infrared and temperature programmed desorption (TPD) studies of the three isomers from model interstellar ices adsorbed on a carbonaceous dust grain analogue surface. Laboratory infrared data show that the isomers can be clearly distinguished on the basis of their infrared spectra, which has implications for observations of interstellar ice spectra. Laboratory TPD data also show that the three isomers can be distinguished on the basis of their thermal desorption behaviour. In particular, TPD data show that the isomers cannot be treated the same way in astrophysical models of desorption. The desorption of glycolaldehyde and acetic acid from water-dominated ices is very similar, with desorption being mainly dictated by water ice. However, methyl formate also desorbs from the surface of the ice, as a pure desorption feature, and therefore desorbs at a lower temperature than the other two isomers. This is more clearly indicated by models of the desorption on astrophysical time-scales corresponding to the heating rate of 25 and 5 M⊙ stars. For a 25 M⊙ star, our model shows that a proportion of the methyl formate can be found in the gas phase at earlier times compared to glycolaldehyde and acetic acid. This has implications for the observation and detection of these molecules, and potentially explains why methyl formate has been observed in a wider range of astrophysical environments than the other two isomers.

  4. XAS and RIXS study of acetic acid and methyl formate in liquid

    NASA Astrophysics Data System (ADS)

    Takahashi, O.; Nishida, N.; Kanai, S.; Horikawa, Y.; Tokushima, T.

    2016-05-01

    Structure of acetic acid (AA) and methyl formate (MF) in the liquid phase is studied using X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) experimentally and theoretically. Two distinct XES spectra are observed by tuning photon energy for both molecules. Model structure in the liquid phase is constructed using the classical and first principle molecular dynamics simulations, and XES spectra are calculated using density functional theory. Calculated XES spectra are consistent with experimental ones. The effect of core-hole induced excited state molecular dynamics are discussed.

  5. Undergraduate Analytical Chemistry Experiment: The Determination of Formation Constants for Acetate and Mono-and Dichloroacetate Salts of Primary, Secondary, and Tertiary Methyl-and Ethylamines

    ERIC Educational Resources Information Center

    D'Amelia, Ronald P.; Chiang, Stephanie; Pollut, Stephanie; Nirode, William F.

    2014-01-01

    The formation and the hydrolysis of organic salts produced by the titration of a 0.1 M solution of the following amines: methyl-, dimethyl-, trimethyl-, ethyl-, diethyl-, and triethylamine with a 0.1 M solution of acetic, chloroacetic, and dichloracetic acids are studied. The pK[subscript b] of the amine and the pH at the end point were determined…

  6. Acetaldehyde partial oxidation on the Au(111) model catalyst surface: C-C bond activation and formation of methyl acetate as an oxidative coupling product

    NASA Astrophysics Data System (ADS)

    Karatok, Mustafa; Vovk, Evgeny I.; Shah, Asad A.; Turksoy, Abdurrahman; Ozensoy, Emrah

    2015-11-01

    Partial oxidation of acetaldehyde (CH3CHO) on the oxygen pre-covered Au(111) single crystal model catalyst was investigated via Temperature Programmed Desorption (TPD) and Temperature Programmed Reaction Spectroscopy (TPRS) techniques, where ozone (O3) was utilized as the oxygen delivery agent providing atomic oxygen to the reacting surface. We show that for low exposures of O3 and small surface oxygen coverages, two partial oxidation products namely, methyl acetate (CH3COOCH3) and acetic acid (CH3COOH) can be generated without the formation of significant quantities of carbon dioxide. The formation of methyl acetate as the oxidative coupling reaction product implies that oxygen pre-covered Au(111) single crystal model catalyst surface can activate C-C bonds. In addition to the generation of these products; indications of the polymerization of acetaldehyde on the gold surface were also observed as an additional reaction route competing with the partial and total oxidation pathways. The interplay between the partial oxidation, total oxidation and polymerization pathways reveals the complex catalytic chemistry associated with the interaction between the acetaldehyde and atomic oxygen on catalytic gold surfaces.

  7. Search for Deuterated methyl acetate in the ISM

    NASA Astrophysics Data System (ADS)

    Gorai, Prasanta; Chakrabarti, Sandip Kumar; Das, Ankan; Majumdar, Liton; Sahu, Dipen; Sivaraman, Bhalamurugan

    2016-07-01

    Methyl acetate (CH_3COOCH_3 ) has been recently observed by IRAM 30 m radio telescope in Orion. But the existence of its deuterated form are yet to be confirmed. Here, we study the properties of methyl acetate and its singly deuterated forms (CH_3COOCH_3, CH_2DCOOCH_3 and CH_3COOCH_2D). Our simulation results reveal that deuterated forms of methyl acetate could efficiently be produced both in gas as well as in ice phase. Production of methyl acetate could follow radical-radical reaction between acetyl (CH_3CO) and methoxy (CH_3O) radicals. To predict abundances of CH_3COOCH_3 along with its two singly deuterated isotopomers and its two isomers (ethyl formate and hydroxy acetone), we prepare a large gas-grain chemical network to study chemical evolution of these molecules. Since gas phase rate coefficients of our newly adopted network for methyl acetate and its related species were unknown, in our simulation, either we consider similar rate coefficients for similar types of reactions (by following existing data bases) or we carry out quantum chemical calculations to estimate the unknown rate coefficients. For the surface reactions, we use adsorption energies of reactants from some earlier studies. Moreover, we perform quantum chemical calculations to find out various spectral properties of various forms of methyl acetate in infrared, ultraviolet and sub-millimeter regions. We prepare two catalog files for the rotational transitions of CH_2DCOOCH_3 and CH_3COOCH_2D in JPL format, which might be useful for its detection in regions of interstellar media where CH_3COOCH_3 has already been observed.

  8. Phytogenic biosynthesis and emission of methyl acetate.

    PubMed

    Jardine, Kolby; Wegener, Frederik; Abrell, Leif; van Haren, Joost; Werner, Christiane

    2014-02-01

    Acetylation of plant metabolites fundamentally changes their volatility, solubility and activity as semiochemicals. Here we present a new technique termed dynamic (13) C-pulse chasing to track the fate of C1-3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO2 . (13) C-labelling of MA and CO2 branch emissions respond within minutes to changes in (13) C-positionally labelled pyruvate solutions fed through the transpiration stream. Strong (13) C-labelling of MA emissions occurred only under pyruvate-2-(13) C and pyruvate-2,3-(13) C feeding, but not pyruvate-1-(13) C feeding. In contrast, strong (13) CO2 emissions were only observed under pyruvate-1-(13) C feeding. These results demonstrate that MA (and other volatile and non-volatile metabolites) derive from the C2,3 atoms of pyruvate while the C1 atom undergoes decarboxylation. The latter is a non-mitochondrial source of CO2 in the light generally not considered in studies of CO2 sources and sinks. Within a tropical rainforest mesocosm, we also observed atmospheric concentrations of MA up to 0.6 ppbv that tracked light and temperature conditions. Moreover, signals partially attributed to MA were observed in ambient air within and above a tropical rainforest in the Amazon. Our study highlights the potential importance of acetyl coenzyme A (CoA) biosynthesis as a source of acetate esters and CO2 to the atmosphere. PMID:23862653

  9. Transition-Metal-Catalyzed Carbonylation of Methyl Acetate.

    ERIC Educational Resources Information Center

    Polichnowski, S. W.

    1986-01-01

    Presents a study of the rhodium-catalyzed, ioding-promoted carbonylation of methyl acetate. This study provides an interesting contrast between the carbonylation of methyl acetate and the carbonylation of methanol when similar rhodium/iodine catalyst systems are used. (JN)

  10. Methyl Acetate and Its Singly Deuterated Isotopomers in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Das, Ankan; Majumdar, Liton; Sahu, Dipen; Gorai, Prasanta; Sivaraman, B.; Chakrabarti, Sandip K.

    2015-07-01

    Methyl acetate ({{CH}}3{{COOCH}}3) has been recently observed by the IRAM 30 m radio telescope in Orion, though the presence of its deuterated isotopomers is yet to be confirmed. We therefore study the properties of various forms of methyl acetate, namely, {{CH}}3{{COOCH}}3, {{CH}}2{{DCOOCH}}3, and {{CH}}3{{COOCH}}2{{D}}. Our simulation reveals that these species could be produced efficiently in both gas and ice phases. Production of methyl acetate could follow radical-radical reaction between acetyl ({{CH}}3{CO}) and methoxy ({{CH}}3{{O}}) radicals. To predict abundances of {{CH}}3{{COOCH}}3 along with its two singly deuterated isotopomers and its two isomers (ethyl formate and hydroxyacetone), we prepare a gas-grain chemical network to study the chemical evolution of these molecules. Since gas-phase rate coefficients for methyl acetate and its related species are unknown, either we consider similar rate coefficients for similar types of reactions (by following existing databases) or we carry out quantum chemical calculations to estimate the unknown rate coefficients. For the surface reactions, we use adsorption energies of reactants from some earlier studies. Moreover, we perform quantum chemical calculations to obtain spectral properties of methyl acetate in infrared and sub-millimeter regions. We prepare two catalog files for the rotational transitions of {{CH}}2{{DCOOCH}}3 and {{CH}}3{{COOCH}}2{{D}} in JPL format, which could be useful for their detection in regions of interstellar media where {{CH}}3{{COOCH}}3 has already been observed.

  11. Heterogeneous catalyst for the production of acetic anhydride from methyl acetate

    DOEpatents

    Ramprasad, Dorai; Waller, Francis Joseph

    1999-01-01

    This invention relates to a process for producing acetic anhydride by the reaction of methyl acetate, carbon monoxide, and hydrogen at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that contains an insoluble polymer having pendant quaternized phosphine groups, some of which phosphine groups are ionically bonded to anionic Group VIII metal complexes, the remainder of the phosphine groups being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for consecutive runs without loss in activity. Bifunctional catalysts for use in carbonylating dimethyl ether are also provided.

  12. Heterogeneous catalyst for the production of acetic anhydride from methyl acetate

    DOEpatents

    Ramprasad, D.; Waller, F.J.

    1999-04-06

    This invention relates to a process for producing acetic anhydride by the reaction of methyl acetate, carbon monoxide, and hydrogen at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that contains an insoluble polymer having pendant quaternized phosphine groups, some of which phosphine groups are ionically bonded to anionic Group VIII metal complexes, the remainder of the phosphine groups being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for consecutive runs without loss in activity. Bifunctional catalysts for use in carbonylating dimethyl ether are also provided.

  13. Vacuum ultraviolet and infrared spectra of condensed methyl acetate on cold astrochemical dust analogs

    SciTech Connect

    Sivaraman, B.; Nair, B. G.; Mason, N. J.; Lo, J.-I.; Cheng, B.-M.; Kundu, S.; Davis, D.; Prabhudesai, V.; Krishnakumar, E.; Raja Sekhar, B. N.

    2013-12-01

    Following the recent report of the first identification of methyl acetate (CH{sub 3}COOCH{sub 3}) in the interstellar medium (ISM), we have carried out vacuum ultraviolet (VUV) and infrared (IR) spectroscopy studies on methyl acetate from 10 K until sublimation in an ultrahigh vacuum chamber simulating astrochemical conditions. We present the first VUV and IR spectra of methyl acetate relevant to ISM conditions. Spectral signatures clearly showed molecular reorientation to have started in the ice by annealing the amorphous ice formed at 10 K. An irreversible phase change from amorphous to crystalline methyl acetate ice was found to occur between 110 K and 120 K.

  14. Photoinduced amino-imino tautomerization reaction in 2-aminopyrimidine and its methyl derivatives with acetic acid.

    PubMed

    Kitamura, Teruyoshi; Hikita, Atushi; Ishikawa, Hironori; Fujimoto, Akira

    2005-12-01

    The electronic absorption and fluorescence spectra of 2-aminopyrimidine (2APM), 2-amino-4-methylpyrimidine (2A4MPM), and 2-amino-4,6-dimethylpyrimidine (2ADMPM) with acetic acid (AcOH) were measured in isooctane (2,2,4-trimethylpentane) at room temperature. From the absorption spectra, a hydrogen-bonded complex formation of the 2APM/AcOH, 2A4MPM/AcOH, and 2ADMPM/AcOH systems was recognized in isooctane. The enthalpy changes (-DeltaH) for the complex formation were estimated to be ca. 41.2-45.1 kJ mol-1 and increased in proportion to the numbers of the methyl group introduced into the 2APM. The -DeltaH values refer to the formation of the hydrogen-bonded 1:1 complex between the ring nitrogen atom and NH2 group of the aminopyrimidine and the OH and CO groups of AcOH, respectively. In the 2A4MPM/AcOH double hydrogen-bonded complex the OH group of AcOH is thought to be linked to the ring nitrogen at the 1-postion of 2A4MPM. The fluorescence spectral results indicate that the double proton transfer reaction takes place during the excited state, and gives rise to an imino-tautomer vibration emission, from analogy with the fluorescences of 1-methyl-2(1H)-pyrimidinimine (MPMI), 1,4-dimethyl-2(1H)-pyrimidinimine (DMPMI), and 1,4,6-trimethyl-2(1H)-pyrimidinimine (TMPMI). The fluorescence quantum yields of the imino-tautomers also increased in proportion to the numbers of the methyl group introduced into the 2APM. PMID:15978861

  15. Photoinduced amino-imino tautomerization reaction in 2-aminopyrimidine and its methyl derivatives with acetic acid

    NASA Astrophysics Data System (ADS)

    Kitamura, Teruyoshi; Hikita, Atushi; Ishikawa, Hironori; Fujimoto, Akira

    2005-12-01

    The electronic absorption and fluorescence spectra of 2-aminopyrimidine (2APM), 2-amino-4-methylpyrimidine (2A4MPM), and 2-amino-4,6-dimethylpyrimidine (2ADMPM) with acetic acid (AcOH) were measured in isooctane (2,2,4-trimethylpentane) at room temperature. From the absorption spectra, a hydrogen-bonded complex formation of the 2APM/AcOH, 2A4MPM/AcOH, and 2ADMPM/AcOH systems was recognized in isooctane. The enthalpy changes (-Δ H) for the complex formation were estimated to be ca. 41.2-45.1 kJ mol -1 and increased in proportion to the numbers of the methyl group introduced into the 2APM. The -Δ H values refer to the formation of the hydrogen-bonded 1:1 complex between the ring nitrogen atom and NH 2 group of the aminopyrimidine and the OH and C dbnd O groups of AcOH, respectively. In the 2A4MPM/AcOH double hydrogen-bonded complex the OH group of AcOH is thought to be linked to the ring nitrogen at the 1-postion of 2A4MPM. The fluorescence spectral results indicate that the double proton transfer reaction takes place during the excited state, and gives rise to an imino-tautomer vibration emission, from analogy with the fluorescences of 1-methyl-2(1H)-pyrimidinimine (MPMI), 1,4-dimethyl-2(1H)-pyrimidinimine (DMPMI), and 1,4,6-trimethyl-2(1H)-pyrimidinimine (TMPMI). The fluorescence quantum yields of the imino-tautomers also increased in proportion to the numbers of the methyl group introduced into the 2APM.

  16. Enantioselective syntheses and sensory properties of 2-methyl-tetrahydrofuran-3-thiol acetates.

    PubMed

    Dai, Yifeng; Shao, Junqiang; Yang, Shaoxiang; Sun, Baoguo; Liu, Yongguo; Ning, Ting; Tian, Hongyu

    2015-01-21

    The enantioselective synthesis of four stereoisomers of 2-methyl-tetrahydrofuran-3-thiol acetate was achieved. The two enantiomers of the important intermediate cis-2-methyl-3-hydroxy-tetrahydrofuran were obtained by Sharpless asymmetric dihydroxylation (AD), whereas the two enantiomers of trans-2-methyl-3-hydroxy-tetrahydrofuran were derived from the corresponding optically active cis-isomers by Mitsunobu reaction. Each stereoisomer of 2-methyl-3-hydroxy-tetrahydrofuran went through mesylation and nucleophilic substitution to afford the corresponding product with specific configuration. (2R,3S)- and (2R,3R)-2-methyl-tetrahydrofuran-3-thiol acetate were obtained in 80% ee, whereas the (2S,3R)- and (2S,3S)-isomers were in 62% ee. The odor properties of the synthesized four stereoisomers were evaluated by gas chromatography-olfactometry (GC-O), which revealed perceptible differences among stereoisomers both in odor features and in intensities. PMID:25560460

  17. A shock tube laser schlieren study of methyl acetate dissociation in the fall-off regime.

    PubMed

    Annesley, Christopher J; Franklin Goldsmith, C; Tranter, Robert S

    2014-04-28

    The pyrolysis of methyl acetate, 2% and 4% dilute in krypton, was investigated in a diaphragmless shock tube (DFST) using laser schlieren densitometry (LS). Experiments were performed at 122 ± 3 and 63 ± 2 Torr over the temperature range of 1492-2266 K. Master equation models for the four main dissociation paths of methyl acetate based on a prior study by Peukert et al. [S. Peukert, R. Sivaramakrishnan, M. Su and J. Michael, Combust. Flame, 2012, 159, 2312-2323] were refined and formed the basis for simulating the LS experiments. The density gradient profiles from the LS experiments indicate that the initial dissociation proceeds predominantly by breakage of the C-O bond leading ultimately to two methyl radicals and CO2, accounting for 83-88% of the methyl acetate loss over this temperature range. Rate coefficients for dissociation of methyl acetate were satisfactorily simulated with a master equation model, with modelled rate coefficients of k120 Torr = 9.06 × 10(81) × T(-19.07) × exp(-61 600K/T) s(-1), k60 Torr = 3.71 × 10(82) × T(-19.34) × exp(-61 200K/T) s(-1), and of k∞ = 1.97 × 10(30) × T(-3.80) × exp(-47 900K/T) s(-1) for the major channel, based on fitting to 120 Torr and 60 Torr data taken in this study. The model also captures the pressure dependency of methyl acetate dissociation and resolves an earlier discrepancy concerning the mechanism of dissociation of methyl acetate. PMID:24608752

  18. Thermodynamic properties and ideal-gas enthalpies of formation for 2-aminoisobutyric acid (2-methylalanine), acetic acid, (Z)-5-ethylidene-2-norbornene, mesityl oxide (4-methyl-3-penten-2-one), 4-methylpent-1-ene, 2,2{prime}-bis(phenylthio)propane, and glycidyl phenyl ether (1,2-epoxy-3-phenoxypropane)

    SciTech Connect

    Steele, W.V.; Chirico, R.D.; Cowell, A.B.; Knipmeyer, S.E.; Nguyen, A.

    1997-11-01

    The results of a study aimed at improvement of group-contribution methodology for estimation of thermodynamic properties of organic substances are reported. Specific weaknesses where particular group-contribution terms were unknown, or estimated because of lack of experimental data, are addressed by experimental studies of enthalpies of combustion in the condensed phase, vapor-pressure measurements, and differential scanning calorimetric (DSC) heat-capacity measurements. Ideal-gas enthalpies of formation of acetic acid, (Z)-5-ethylidene-2-norbornene, mesityl oxide (4-methyl-3-penten-2-one), 4-methylpent-1-ene, glycidyl phenyl ether (1,2-epoxy-3-phenoxypropane), and 2,2{prime}-bis(phenylthio)propane are reported. An enthalpy of formation of 2-aminoisobutyric acid (2-methylalanine) in the crystalline phase was determined. Using a literature value for the enthalpy of sublimation of 2-aminoisobutyric acid, a value for the ideal-gas enthalpy of formation was derived. An enthalpy of fusion was determined for 2,2{prime}-bis(phenylthio)propane. Two-phase (solid + vapor) or (liquid + vapor) heat capacities were determined from 300 K to the critical region or earlier decomposition temperature for all the compounds except acetic acid. For mesityl oxide and 4-methylpent-1-ene, critical temperatures and critical densities were determined from the DSC results and corresponding critical pressures derived from the fitting procedures. Group-additivity parameters and ring strain energies useful in the application of group-contribution correlations were derived.

  19. Selective methylation of kaempferol via benzylation and deacetylation of kaempferol acetates.

    PubMed

    Mei, Qinggang; Wang, Chun; Yuan, Weicheng; Zhang, Guolin

    2015-01-01

    A strategy for selective mono-, di- and tri-O-methylation of kaempferol, predominantly on the basis of selective benzylation and controllable deacetylation of kaempferol acetates, was developed. From the selective deacetylation and benzylation of kaempferol tetraacetate (1), 3,4',5,-tri-O-acetylkaempferol (2) and 7-O-benzyl-3,4'5,-tri-O-acetylkaempferol (8) were obtained, respectively. By controllable deacetylation and followed selective or direct methylation of these two intermediates, eight O-methylated kaempferols were prepared with 51-77% total yields from kaempferol. PMID:25815082

  20. 40 CFR 721.10448 - Acetic acid, hydroxy- methoxy-, methyl ester, reaction products with substituted alkylamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ester, reaction products with substituted alkylamine (generic). 721.10448 Section 721.10448 Protection... NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10448 Acetic acid, hydroxy- methoxy-, methyl ester, reaction products with substituted alkylamine (generic)....

  1. Low temperature synthesis of methyl formate

    DOEpatents

    Mahajan, Devinder; Slegeir, William A.; Sapienza, Richard S.; O'Hare, Thomas E.

    1986-01-01

    A gas reaction process for the preferential production of methyl formate over the co-production of methanol wherein the reactant ratio of CO/H.sub.2 is upgraded and this reaction takes place at low temperatures of 50.degree.-150.degree. C. and moderate pressures of .gtoreq.100 psi.

  2. Methyl 2-(2-methyl-4-nitro-1H-imidazol-1-yl)acetate

    PubMed Central

    Zama, Sana; Bouraiou, Abdelmalek; Bouacida, Sofiane; Roisnel, Thierry; Belfaitah, Ali

    2013-01-01

    In the crystal of the title compound, C7H9N3O4, mol­ecules are linked by weak C—H⋯O hydrogen bonds into chains along the a-axis direction. The dihedral angle between the ring and the nitro group is 3.03 (6), while that between the ring and the acetate group is 85.01 (3)°. PMID:23795026

  3. 40 CFR 721.304 - Acetic acid, [(5-chloro-8-quinolinyl)oxy-], 1-methyl hexyl ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.304 Acetic acid, , 1-methyl hexyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as acetic acid, -, 1-methylhexyl ester (PMN...

  4. 40 CFR 721.304 - Acetic acid, [(5-chloro-8-quinolinyl)oxy-], 1-methyl hexyl ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.304 Acetic acid, , 1-methyl hexyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as acetic acid, -, 1-methylhexyl ester (PMN...

  5. Ketene as a Reaction Intermediate in the Carbonylation of Dimethyl Ether to Methyl Acetate over Mordenite.

    PubMed

    Rasmussen, Dominik B; Christensen, Jakob M; Temel, Burcin; Studt, Felix; Moses, Poul Georg; Rossmeisl, Jan; Riisager, Anders; Jensen, Anker D

    2015-06-15

    Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2CO) as a reaction intermediate. The formation of ketene is predicted by detailed DFT calculations and verified experimentally by the observation of doubly deuterated acetic acid (CH2DCOOD), when D2O is introduced in the feed during the carbonylation reaction. PMID:25967363

  6. Pyruvate Formate-Lyase Enables Efficient Growth of Escherichia coli on Acetate and Formate.

    PubMed

    Zelcbuch, Lior; Lindner, Steffen N; Zegman, Yonatan; Vainberg Slutskin, Ilya; Antonovsky, Niv; Gleizer, Shmuel; Milo, Ron; Bar-Even, Arren

    2016-05-01

    Pyruvate formate-lyase (PFL) is a ubiquitous enzyme that supports increased ATP yield during sugar fermentation. While the PFL reaction is known to be reversible in vitro, the ability of PFL to support microbial growth by condensing acetyl-CoA and formate in vivo has never been directly tested. Here, we employ Escherichia coli mutant strains that cannot assimilate acetate via the glyoxylate shunt and use carbon labeling experiments to unequivocally demonstrate PFL-dependent co-assimilation of acetate and formate. Moreover, PFL-dependent growth is faster than growth on acetate using the glyoxylate shunt. Hence, growth via the reverse activity of PFL could have substantial ecological and biotechnological significance. PMID:27093333

  7. Dynamic nuclear polarization of carbonyl and methyl 13C spins in acetate using trityl OX063

    NASA Astrophysics Data System (ADS)

    Niedbalski, Peter; Parish, Christopher; Lumata, Lloyd

    2015-03-01

    Hyperpolarization via dissolution dynamic nuclear polarization (DNP) is a physics technique that amplifies the magnetic resonance signals by several thousand-fold for biomedical NMR spectroscopy and imaging (MRI). Herein we have investigated the effect of carbon-13 isotopic location on the DNP of acetate (one of the biomolecules commonly used for hyperpolarization) at 3.35 T and 1.4 K using a narrow ESR linewidth free radical trityl OX063. We have found that the carbonyl 13C spins yielded about twice the polarization produced in methyl 13C spins. Deuteration of the methyl group, beneficial in the liquid-state, did not produce an improvement in the polarization level at cryogenic conditions. Concurrently, the solid-state nuclear relaxation of these samples correlate with the polarization levels achieved. These results suggest that the location of the 13C isotopic labeling in acetate has a direct impact on the solid-state polarization achieved and is mainly governed by the nuclear relaxation leakage factor.

  8. Ab Initio Kinetics of Hydrogen Abstraction from Methyl Acetate by Hydrogen, Methyl, Oxygen, Hydroxyl, and Hydroperoxy Radicals.

    PubMed

    Tan, Ting; Yang, Xueliang; Krauter, Caroline M; Ju, Yiguang; Carter, Emily A

    2015-06-18

    The kinetics of hydrogen abstraction by five radicals (H, O((3)P), OH, CH3, and HO2) from methyl acetate (MA) is investigated theoretically in order to gain further understanding of certain aspects of the combustion chemistry of biodiesels, such as the effect of the ester moiety. We employ ab initio quantum chemistry methods, coupled cluster singles and doubles with perturbative triples correction (CCSD(T)) and multireference averaged coupled pair functional theory (MRACPF2), to predict chemically accurate reaction energetics. Overall, MRACPF2 predicts slightly higher barrier heights than CCSD(T) for MA + H/CH3/O/OH, but slightly lower barrier heights for hydrogen abstraction by HO2. Based on the obtained reaction energies, we also report high-pressure-limit rate constants using transition state theory (TST) in conjunction with the separable-hindered-rotor approximation, the variable reaction coordinate TST, and the multi-structure all-structure approach. The fitted modified Arrhenius expressions are provided over a temperature range of 250 to 2000 K. The predictions are in good agreement with available experimental results. Abstractions from both of the methyl groups in MA are expected to contribute to consumption of the fuel as they exhibit similar rate coefficients. The reactions involving the OH radical are predicted to have the highest rates among the five abstracting radicals, while those initiated by HO2 are expected to be the lowest. PMID:25974050

  9. Structure and Rotational Dynamics of Isoamyl Acetate and Methyl Propionate Studied by Microwave Spectroscopy

    NASA Astrophysics Data System (ADS)

    Stahl, W.; Nguyen, H. V. L.; Sutikdja, L. W.; Jelisavac, D.; Mouhib, H.; Kleiner, I.

    2012-06-01

    The microwave spectra of a number of organic aliphatic esters have been recorded for the first time in the 3-26.5 GHz frequency range, using the molecular beam Fourier-transform microwave (MB-FTMW) spectrometer in Aachen, with an instrumental uncertainty of a few kHz for unblended lines. The combined use of ab initio quantum chemical calculations and spectral analysis allowed us to determine the spectroscopic parameters and potential barriers to internal rotation of the methyl groups for the lowest energy conformers. We will compare here the results from ab initio calculations and from two different hamiltonian methods (the XIAM and BELGI codes) for isoamyl acetate H3C-COO-(CH2)2-CH(CH3)2, an one-top internal rotor molecule with a C1 symmetry and for methyl propionate CH3CH2COOCH3 containing two inequivalent methyl tops (C3v), with different barrier heights. This study is part of a larger project which aims at determining the structures of the lowest energy conformers for a serie of organic esters and ketones which are of interest for flavour or perfume applications.

  10. Abundances and excitation of interstellar methyl formate

    NASA Technical Reports Server (NTRS)

    Churchwell, E.; Nash, A.; Rahe, J.; Walmsley, C. M.; Lochner, O.; Winnewisser, G.

    1980-01-01

    The detection of methyl formate (HCOOCH3) in four transitions toward Orion KL, in two transitions toward Sagitarrius B2, and in one transition toward W51 is reported. The column densities of HCOOCH3 are found to be surprisingly large (2-5 x 10 to the 14th per sq cm) in all three clouds. Stimulated emission in the 18 cm K doublet of HCOOCH3 toward Sagittarius B2 is clearly demonstrated. The relatively large column densities of HCOOCH3 in clouds outside the galactic-center region probably imply that this molecule is widely distributed in the galaxy, but the negative results in other clouds require lower column densities than in Orion by a factor of 0.5 or less. Two unidentified lines were detected in Orion, at approx. 91 and 99 GHz.

  11. C-type transitions in methyl formate

    NASA Technical Reports Server (NTRS)

    Plummer, Grant M.; Herbst, Eric; De Lucia, Frank C.

    1987-01-01

    Based on previously determined spectral constants for methyl formate in its ground torsional degenerate substate, the frequencies and intensities of forbidden c-type transitions in this molecule, which is represented by a large number of lines in OMC-1, are calculated along with other 'forbidden' transitions labeled x-type. The stronger c-type transitions below 300 GHz with angular momentum quantum number of 30 or less and with upper state rotational energy of 350/cm or less are included in a list of spectral frequencies presented in this paper. Because the c-type transitions borrow intensity from the b-type transitions, the intensities of strongly affected b-type spectra are recalculated and presented.

  12. Amonia gas: an improved reagent for chemical ionization mass spectrometry of bile acid methyl ester acetates

    SciTech Connect

    DeMark, B.R.; Klein, P.D.

    1981-01-01

    The ammonia chemical ionization mass spectra of 28 methyl ester acetate derivatives of bile acids and related compounds have been determined by gas-liquid chromatography-mass spectrometry. Advantages of ammonia ionization over the previously studied isobutane ionization include a 130 to 270% enhancement in the sensitivity of base peak monitoring, and direct determination of molecular weight from the base peak (M + NH/sub 4//sup +/) in the mass spectrum of any of the derivatives. Minor ions in the ammonia spectra also allow selective detection of 3-keto compounds and can indicate unsaturation or double bond conjugation in the molecule. The significance of these studies for the detection and quantitation of bile acids is discussed. 2 tables.

  13. Formation of methyl iodide on a natural manganese oxide.

    PubMed

    Allard, Sébastien; Gallard, Hervé; Fontaine, Claude; Croué, Jean-Philippe

    2010-08-01

    This paper demonstrates that manganese oxides can initiate the formation of methyl iodide, a volatile compound that participates to the input of iodine into the atmosphere. The formation of methyl iodide was investigated using a natural manganese oxide in batch experiments for different conditions and concentrations of iodide, natural organic matter (NOM) and manganese oxide. Methyl iodide was formed at concentrations methyl iodide increased with increasing initial concentrations of iodide ion and Mn sand and when pH decreased from 7 to 5. The hydrophilic NOM isolate exhibited the lowest yield of methyl iodide whereas hydrophobic NOM isolates such as Suwannee River HPOA fraction produced the highest concentration of methyl iodide. The formation of methyl iodide could take place through the oxidation of NOM on manganese dioxide in the presence of iodide. However, the implication of elemental iodine cannot be excluded at acidic pH. Manganese oxides can then participate with ferric oxides to the formation of methyl iodide in soils and sediments. The formation of methyl iodide is unlikely in technical systems such as drinking water treatment i.e. for ppt levels of iodide and low contact times with manganese oxides. PMID:20580399

  14. Occurrence and Sources of Triterpenoid Methyl Ethers and Acetates in Sediments of the Cross-River System, Southeast Nigeria

    PubMed Central

    Oyo-Ita, Orok E.; Ekpo, Bassey O.; Oros, Daniel R.; Simoneit, Bernd R. T.

    2010-01-01

    Pentacyclic triterpenol methyl ethers (PTMEs), germanicol methyl ether (miliacin), 3-methoxyfern-9(11)-ene (arundoin), β-amyrin methyl ether (iso-sawamilletin), and 3-methoxytaraxer-14-ene (sawamilletin or crusgallin) were characterized in surface sediments of the Cross-River system using gas chromatography-mass spectrometry (GC-MS). Triterpenol esters (mainly α- and β-amyrinyl acetates and hexanoates, and lupeyl acetate and hexanoate) were also found. These distinct compounds are useful for assessing diagenesis that can occur during river transport of organic detritus. Poaceae, mainly Gramineae and Elaeis guineensis higher plant species, are proposed as primary sources for the PTMEs and esters in the sediments. PTMEs are biomarkers of specific higher plant subspecies, while the triterpenol esters are indicators of early diagenetic alteration of higher plant detritus. PMID:20414350

  15. Acetic Acid Acts as a Volatile Signal To Stimulate Bacterial Biofilm Formation

    PubMed Central

    Chen, Yun; Gozzi, Kevin; Yan, Fang

    2015-01-01

    ABSTRACT Volatiles are small air-transmittable chemicals with diverse biological activities. In this study, we showed that volatiles produced by the bacterium Bacillus subtilis had a profound effect on biofilm formation of neighboring B. subtilis cells that grew in proximity but were physically separated. We further demonstrated that one such volatile, acetic acid, is particularly potent in stimulating biofilm formation. Multiple lines of genetic evidence based on B. subtilis mutants that are defective in either acetic acid production or transportation suggest that B. subtilis uses acetic acid as a metabolic signal to coordinate the timing of biofilm formation. Lastly, we investigated how B. subtilis cells sense and respond to acetic acid in regulating biofilm formation. We showed the possible involvement of three sets of genes (ywbHG, ysbAB, and yxaKC), all encoding putative holin-antiholin-like proteins, in cells responding to acetic acid and stimulating biofilm formation. All three sets of genes were induced by acetate. A mutant with a triple mutation of those genes showed a severe delay in biofilm formation, whereas a strain overexpressing ywbHG showed early and robust biofilm formation. Results of our studies suggest that B. subtilis and possibly other bacteria use acetic acid as a metabolic signal to regulate biofilm formation as well as a quorum-sensing-like airborne signal to coordinate the timing of biofilm formation by physically separated cells in the community. PMID:26060272

  16. Methyl N-phenyl carbamate synthesis from aniline and methyl formate: carbon recycling to chemical products.

    PubMed

    Yalfani, Mohammad S; Lolli, Giulio; Müller, Thomas E; Wolf, Aurel; Mleczko, Leslaw

    2015-02-01

    Methyl N-phenyl carbamate was synthesized from aniline by using methyl formate as a green and efficient carbonylating agent. High yields were obtained at milder reaction conditions compared to the conventional CO/CH3 OH route. Studies on the reaction sequence led to suggest an alternative and more efficient route to the carbamate via formanilide as intermediate. PMID:25504838

  17. Abiotic Formation of Methyl Halides in the Terrestrial Environment

    NASA Astrophysics Data System (ADS)

    Keppler, F.

    2011-12-01

    Methyl chloride and methyl bromide are the most abundant chlorine and bromine containing organic compounds in the atmosphere. Since both compounds have relatively long tropospheric lifetimes they can effectively transport halogen atoms from the Earth's surface, where they are released, to the stratosphere and following photolytic oxidation form reactive halogen gases that lead to the chemical destruction of ozone. Methyl chloride and methyl bromide account for more than 20% of the ozone-depleting halogens delivered to the stratosphere and are predicted to grow in importance as the chlorine contribution to the stratosphere from anthropogenic CFCs decline. Today methyl chloride and methyl bromide originate mainly from natural sources with only a minor fraction considered to be of anthropogenic origin. However, until as recently as 2000 most of the methyl chloride and methyl bromide input to the atmosphere was considered to originate from the oceans, but investigations in recent years have clearly demonstrated that terrestrial sources such as biomass burning, wood-rotting fungi, coastal salt marshes, tropical vegetation and organic matter degradation must dominate the atmospheric budgets of these trace gases. However, many uncertainties still exist regarding strengths of both sources and sinks, as well as the mechanisms of formation of these naturally occurring halogenated gases. A better understanding of the atmospheric budget of both methyl chloride and methyl bromide is therefore required for reliable prediction of future ozone depletion. Biotic and abiotic methylation processes of chloride and bromide ion are considered to be the dominant pathways of formation of these methyl halides in nature. In this presentation I will focus on abiotic formation processes in the terrestrial environment and the potential parameters that control their emissions. Recent advances in our understanding of the abiotic formation pathway of methyl halides will be discussed. This will

  18. The effect of materials selection on metals reduction in propylene glycol methyl ether acetate, PGMEA

    NASA Astrophysics Data System (ADS)

    Entezarian, Majid; Geiger, Bob

    2016-03-01

    The trend in microelectronics fabrication is to produce nano-features measuring down to 10 nm and finer. The PPT levels of organic and inorganic contaminants in the photoresist, solvent and cleaning solutions are becoming a major processing variable affecting the process capability and defectivity. The photoresist usually contains gels, metals, and particulates that could interfere with the lithography process and cause microbridging defects. Nano filters of 5 nm polypropylene, 5 nm polyethylene, and 10 nm natural nylon were used to filter propylene glycol methyl ether acetate PGMEA containing 50 ppb of Na, Mg, Al, Ca, Cr, Mn, Fe, Cu, Zn, and Pb. All filters were effective in removing trivalent Al, Cr, and Fe metals indicating the mechanism for their removal as mechanical sieving. However, the nylon was also very effective in removing the divalent metals showing adsorptive properties. Furthermore, the metal removal of the nylon membrane was studied as a function of surface chemistry. Natural and charged 40 nm nylon membranes were tested and found that charged nylon is more effective for metal removal.

  19. High-resolution infrared spectrum of jet-cooled methyl acetate in the C=O stretching region: internal rotations of two inequivalent methyl tops.

    PubMed

    Sunahori, Fumie X; Borho, Nicole; Liu, Xunchen; Xu, Yunjie

    2011-12-21

    The jet-cooled high resolution infrared (IR) spectrum of methyl acetate (MA), CH(3)-C(=O)-O-CH(3), in the C=O fundamental band region was recorded by using a rapid scan IR laser spectrometer equipped with an astigmatic multipass cell. No high resolution IR analyses of the ro-vibrational transitions between the ground and non-torsionally excited vibrational states have hitherto been reported for molecules with two inequivalent methyl rotors. Because of the two chemically different methyl tops in MA, i.e., the acetyl -CH(3) and methoxy -CH(3), each rotational energy level is split into more than two torsional sublevels by internal rotations of these methyl groups. We were able to assign ro-vibrational transitions of four torsional species by using the ground state combination differences calculated from the molecular constants of the vibrational ground state recently determined by a global fit of the microwave and millimeter wave lines [M. Tudorie, I. Kleiner, J. T. Hougen, S. Melandri, L. W. Sutikdja, and W. Stahl, J. Mol. Spectrosc. 269, 211 (2011)]. The assigned lines were successfully fitted using the BELGI-Cs-IR program to an overall standard deviation which is comparable to the measurement accuracy. This study is also of interest in understanding the role of methyl rotors in the intramolecular vibrational-energy redistribution processes in mid-size organic molecules. PMID:22191878

  20. High-resolution infrared spectrum of jet-cooled methyl acetate in the C=O stretching region: Internal rotations of two inequivalent methyl tops

    NASA Astrophysics Data System (ADS)

    Sunahori, Fumie X.; Borho, Nicole; Liu, Xunchen; Xu, Yunjie

    2011-12-01

    The jet-cooled high resolution infrared (IR) spectrum of methyl acetate (MA), CH3-C(=O)-O-CH3, in the C=O fundamental band region was recorded by using a rapid scan IR laser spectrometer equipped with an astigmatic multipass cell. No high resolution IR analyses of the ro-vibrational transitions between the ground and non-torsionally excited vibrational states have hitherto been reported for molecules with two inequivalent methyl rotors. Because of the two chemically different methyl tops in MA, i.e., the acetyl -CH3 and methoxy -CH3, each rotational energy level is split into more than two torsional sublevels by internal rotations of these methyl groups. We were able to assign ro-vibrational transitions of four torsional species by using the ground state combination differences calculated from the molecular constants of the vibrational ground state recently determined by a global fit of the microwave and millimeter wave lines [M. Tudorie, I. Kleiner, J. T. Hougen, S. Melandri, L. W. Sutikdja, and W. Stahl, J. Mol. Spectrosc. 269, 211 (2011)]. The assigned lines were successfully fitted using the BELGI-Cs-IR program to an overall standard deviation which is comparable to the measurement accuracy. This study is also of interest in understanding the role of methyl rotors in the intramolecular vibrational-energy redistribution processes in mid-size organic molecules.

  1. Photooxidation of Acetone on TiO2(110): Conversion to Acetate via Methyl Radical Ejection

    SciTech Connect

    Henderson, Michael A.

    2005-06-23

    It is generally held that radicals form and participate in heterogeneous photocatalytic processes on oxide surfaces, although understanding the mechanistic origins and fates of such species is difficult. In this study, photodesorption and thermal desorption techniques show that acetone is converted into acetate on the surface of TiO(110) in a two step process that involves, first, a thermal reaction between acetone and coadsorbed oxygen to make a surface acetone-oxygen complex, followed second by a photochemical reaction that ejects a methyl radical from the surface and converts the acetone-oxygen complex into acetate. Designation of the photodesorption species to methyl radicals was confirmed using isotopically labeled acetone. The yield of photodesorbed methyl radicals correlates well with the amount depleted of acetone and with the yield of acetate left on the surface, both gauged using post-irradiation temperature programmed desorption (TPD). The thermal reaction between adsorbed acetone and oxygen to form the acetone-oxygen complex exhibits an approximate activation barrier of about 10 kJ/mol. A prerequisite to this reaction is the presence of surface Ti?? sites that enable O? adsorption. Creation of these sites by vacuum reduction of the surface prior to acetone and oxygen co-adsorption results in an initial spike in the photodecomposition rate, but replenishment of these sites by photolytic means (i.e., by trapping excited electrons at the surface) appears to be a slow step a sustained reaction. Evidence in this study for the ejection of organic radicals from the surface during photo-oxidation catalysis on TiO provides support for mechanistic pathways that involve both adsorbed and non-adsorbed species.

  2. A Gas-phase Formation Route to Interstellar Trans-methyl Formate

    NASA Astrophysics Data System (ADS)

    Cole, Callie A.; Wehres, Nadine; Yang, Zhibo; Thomsen, Ditte L.; Snow, Theodore P.; Bierbaum, Veronica M.

    2012-07-01

    The abundance of methyl formate in the interstellar medium has previously been underpredicted by chemical models. Additionally, grain surface chemistry cannot account for the relative abundance of the cis- and trans-conformers of methyl formate, and the trans-conformer is not even formed at detectable abundance on these surfaces. This highlights the importance of studying formation pathways to methyl formate in the gas phase. The rate constant and branching fractions are reported for the gas-phase reaction between protonated methanol and formic acid to form protonated trans-methyl formate and water as well as adduct ion: Rate constants were experimentally determined using a flowing afterglow-selected ion flow tube apparatus at 300 K and a pressure of 530 mTorr helium. The results indicate a moderate overall rate constant of (3.19 ± 0.39) × 10-10 cm3 s-1 (± 1σ) and an average branching fraction of 0.05 ± 0.04 for protonated trans-methyl formate and 0.95 ± 0.04 for the adduct ion. These experimental results are reinforced by ab initio calculations at the MP2(full)/aug-cc-pVTZ level of theory to examine the reaction coordinate and complement previous density functional theory calculations. This study underscores the need for continued observational studies of trans-methyl formate and for the exploration of other gas-phase formation routes to complex organic molecules.

  3. A GAS-PHASE FORMATION ROUTE TO INTERSTELLAR TRANS-METHYL FORMATE

    SciTech Connect

    Cole, Callie A.; Wehres, Nadine; Yang Zhibo; Thomsen, Ditte L.; Bierbaum, Veronica M.; Snow, Theodore P. E-mail: Nadine.Wehres@colorado.edu E-mail: Veronica.Bierbaum@colorado.edu E-mail: dlt@chem.ku.dk

    2012-07-20

    The abundance of methyl formate in the interstellar medium has previously been underpredicted by chemical models. Additionally, grain surface chemistry cannot account for the relative abundance of the cis- and trans-conformers of methyl formate, and the trans-conformer is not even formed at detectable abundance on these surfaces. This highlights the importance of studying formation pathways to methyl formate in the gas phase. The rate constant and branching fractions are reported for the gas-phase reaction between protonated methanol and formic acid to form protonated trans-methyl formate and water as well as adduct ion: Rate constants were experimentally determined using a flowing afterglow-selected ion flow tube apparatus at 300 K and a pressure of 530 mTorr helium. The results indicate a moderate overall rate constant of (3.19 {+-} 0.39) Multiplication-Sign 10{sup -10} cm{sup 3} s{sup -1} ({+-} 1{sigma}) and an average branching fraction of 0.05 {+-} 0.04 for protonated trans-methyl formate and 0.95 {+-} 0.04 for the adduct ion. These experimental results are reinforced by ab initio calculations at the MP2(full)/aug-cc-pVTZ level of theory to examine the reaction coordinate and complement previous density functional theory calculations. This study underscores the need for continued observational studies of trans-methyl formate and for the exploration of other gas-phase formation routes to complex organic molecules.

  4. Photolytic degradation of chlorophenols from industrial wastewaters by organic oxidants peroxy acetic acid, para nitro benzoic acid and methyl ethyl ketone peroxide: identification of reaction products.

    PubMed

    Sharma, Swati; Mukhopadhyay, Mausumi; Murthy, Zagabathuni Venkata Panchakshari

    2014-01-01

    In this investigation, chlorophenol (CP) containing industrial wastewater was remediated by ultraviolet irradiation in conjunction with organic oxidants, peroxy acetic acid (PAA); para nitro benzoic acid (PNBA); and methyl ethyl ketone peroxide (MEKP). CP mineralization was studied with regard to chemical oxygen demand (COD) and chloride ion release under identical test conditions. COD depletion to the extent of 81% by PAA, 66% by PNBA, and 67% by MEKP was noted along with an upwardly mobile trend of chloride ion release upon irradiation of samples at 254 nm. A 90-99% decrease in CP concentration (as per high pressure liquid chromatography (HPLC) analysis) was achieved with an additional 15.0 ml of organic oxidant in all cases. Gas chromatography high resolution mass spectroscopy (GC-HRMS) results also indicated the formation of such reaction products as are free from chlorine substitutions. This treatment also leads to total decolorization of the collected samples. PMID:24647192

  5. Formation of biologically relevant carboxylic acids during the gamma irradiation of acetic acid

    NASA Technical Reports Server (NTRS)

    Negron-Mendoza, A.; Ponnamperuma, C.

    1976-01-01

    Irradiation of aqueous solutions of acetic acid with gamma rays produced several carboxylic acids in small yield. Their identification was based on the technique of gas chromatography combined with mass spectrometry. Some of these acids are Krebs Cycle intermediates. Their simultaneous formation in experiments simulating the primitive conditions on the earth suggests that metabolic pathways may have had their origin in prebiotic chemical processes.

  6. Engineering of Corynebacterium glutamicum to utilize methyl acetate, a potential feedstock derived by carbonylation of methanol with CO.

    PubMed

    Choo, Seungjung; Um, Youngsoon; Han, Sung Ok; Woo, Han Min

    2016-04-20

    The possibilities to utilize one-carbon substrates (C1) like CO, methane and methanol have been explored as a cheap alternative feedstock in the biotechnology. For the first time, methyl acetate (MeOAc), which can be formed from carbonylation of methanol with CO, was demonstrated to be an alternative carbon source for the cell growth of Corynebacterium glutamicum as a model microbial cell factory. To do so, a carboxyl esterase activity was necessary to hydrolyze MeOAc to methanol and acetate. Although the wild-type has an unknown esterase activity to MeOAc, the activity was not high enough to grow from 270mM MeOAc as sole carbon source, reaching OD600 of 5.28±0.2 in 32h. Based on the literatures studied for the esterase, we chose three esterases (MekB of Pseudomonas veronii MEK700, AcmB of Gordonia sp. Strain TY-5, and Est of Pyrobaculum calidifontis VA1) and cloned into the wild-type. As a result, the recombinant C. glutamicum expressing the highly active MekB esterase (28.6±0.77U/mg protein) showed complete degradation of MeOAc and utilization of acetate, resulting in OD600 of 16.5±0.02at 24h. In addition, the recombinant strain exhibited the rapid degradation of MeOAc to methanol and acetate in 2h under anaerobic condition. Therefore, MeOAc can be used as another C1-derived carbon source in the biotechnology. PMID:26970052

  7. Intermediary Metabolism in Clostridium acetobutylicum: Levels of Enzymes Involved in the Formation of Acetate and Butyrate

    PubMed Central

    Hartmanis, Maris G. N.; Gatenbeck, Sten

    1984-01-01

    The levels of seven intermediary enzymes involved in acetate and butyrate formation from acetyl coenzyme A in the saccharolytic anaerobe Clostridium acetobutylicum were investigated as a function of time in solvent-producing batch fermentations. Phosphate acetyltransferase and acetate kinase, which are known to form acetate from acetyl coenzyme A, both showed a decrease in specific activity when the organism reached the solvent formation stage. The three consecutive enzymes thiolase, β-hydroxybutyrylcoenzyme A dehydrogenase, and crotonase exhibited a coordinate expression and a maximal activity after growth had ceased. Only low levels of butyryl coenzyme A dehydrogenase activity were found. Phosphate butyryltransferase activity rapidly decreased after 20 h from 5 to 11 U/mg of protein to below the detection limit (1 mU/mg). Butyrate no longer can be formed, and the metabolic flux may be diverted to butanol. Butyrate kinase showed a 2.5- to 10-fold increase in specific activity after phosphate butyryltransferase activity no longer could be detected. These results suggest that the uptake of acetate and butyrate during solvent formation can not proceed via a complete reversal of the phosphate transferase and kinase reactions. The activities of all enzymes investigated as a function of time in vitro are much higher than the metabolic fluxes through them in vivo. This indicates that none of the maximal activities of the enzymes assayed is rate limiting in C. acetobutylicum. PMID:16346566

  8. The Spectrum of Methyl Formate in the Thz Region

    NASA Astrophysics Data System (ADS)

    Tudorie, M.; Huet, T. R.; Margules, L.; Goubet, M.; Pirali, O.; Roy, P.; Ilyushin, V. V.; Kleiner, I.

    2009-06-01

    The THz spectrum of methyl formate-HCOOCH_3 is currently investigated. At first a multi-pass cell having an optical path of 150 m coupled to an internal source of the Fourier Transform spectrometer of the AILES beamline, synchrotron SOLEIL (France), was used to obtain the methyl formate THz spectrum. Preliminary assignments of the pure rotation spectrum up to 80 cm^{-1}, and of the very weak torsion band v_t = 1-0 around 130 cm^{-1} are carried out. The assignments are based on the rotation-torsion energy levels calculated using the RAM approach. The particular interest in Δ v_t = 1 torsion-rotation band lies in the direct experimental determination of the barrier height V_3, which up to now was determined from pure rotational transitions only, and consequently in the contribution to the improvement of the global study of the rotational levels in the lowest torsional states of methyl formate. Secondly further measurements using the synchrotron radiation are planned. The latest results will be presented. [2] Ilyushin, Kryvda, Alekseev, J. Mol. Spectrosc. (2009), doi: 10.1016/j.jms.2009.01.016

  9. Vapor-liquid equilibrium measurements at 101. 32 kPa for binary mixtures of methyl acetate + ethanol or 1-propanol

    SciTech Connect

    Ortega, J.: Susial, P.; de Alfonso, C. )

    1990-07-01

    This paper reports on isobaric vapor-liquid equilibrium data at 101.32 {plus minus} 0.02 kPa for methyl acetate (1) + ethane (2) or + 1-propanol (2). The results are compared with those predicted by the UNIFAC and ASOG methods. The methyl acetate (1) + ethanol (2) system forms an azeotrope at 329.8 K and a molar concentration of x{sub 1} = 0.958. Both methods predict the vapor-phase compositions equally well, with overall mean errors of less than 5%.

  10. Configurational and conformational analysis of chiral molecules using IR and VCD spectroscopies: spiropentylcarboxylic acid methyl ester and spiropentyl acetate.

    PubMed

    Devlin, F J; Stephens, P J; Osterle, C; Wiberg, K B; Cheeseman, J R; Frisch, M J

    2002-11-15

    The chiral monosubstituted derivatives of spiropentane, spiropentylcarboxylic acid methyl ester, 1, and spiropentyl acetate, 2, have been synthesized in optically active form. Configurational and conformational analysis of 1 and 2 has been carried out using infrared (IR) and vibrational circular dichroism (VCD) spectroscopies. Analysis of the experimental IR and VCD spectra has been carried out using ab initio density functional theory (DFT). For both 1 and 2, DFT predicts two populated conformations. Comparison to experiment of the conformationally averaged IR and VCD spectra of 1 and 2, predicted using DFT, provides unequivocal evidence of the predicted conformations and yields the absolute configurations R(-)/S(+) for 1 and R(+)/S(-) for 2. These absolute configurations are consistent with the R(-)/S(+) absolute configuration of spiropentylcarboxylic acid, assigned previously via X-ray crystallography of its alpha-phenylethylammonium salt. PMID:12423137

  11. Extension of the measurement, assignment, and fit of the rotational spectrum of the two-top molecule methyl acetate

    NASA Astrophysics Data System (ADS)

    Nguyen, Ha Vinh Lam; Kleiner, Isabelle; Shipman, Steven T.; Mae, Yoshiaki; Hirose, Kazue; Hatanaka, Shota; Kobayashi, Kaori

    2014-05-01

    New and previous spectroscopic data were recorded for the two-top molecule methyl acetate using five spectrometers in four different labs: a room temperature chirped-pulse Fourier transform microwave (FTMW) spectrometer in the frequency range from 8.7 to 26.5 GHz, two molecular beam FTMW spectrometers (2-40 GHz), a free jet absorption Stark-modulated spectrometer (60-78 GHz), and a room temperature millimeter-wave spectrometer (44-68 GHz). Approximately 800 new lines with J up to 40 and K up to 16 were assigned. In total, 1603 lines were fitted with 34 parameters using an internal rotation Hamiltonian in the Rho Axis Method (RAM) and the program BELGI-Cs-2tops to standard deviations close to the experimental uncertainties. More precise determinations of the top-top interaction and the J, K dependent parameters were carried out.

  12. Methane production from formate, acetate and H2/CO2; focusing on kinetics and microbial characterization.

    PubMed

    Pan, Xiaofang; Angelidaki, Irini; Alvarado-Morales, Merlin; Liu, Houguang; Liu, Yuhong; Huang, Xu; Zhu, Gefu

    2016-10-01

    For evaluating the methanogenesis from typical methanogenic precursors (formate, acetate and H2/CO2), CH4 production kinetics were investigated at 37±1°C in batch anaerobic digestion tests and stimulated by modified Gompertz model. The results showed that maximum methanation rate from formate, acetate and H2/CO2 were 19.58±0.49, 42.65±1.17 and 314.64±3.58NmL/gVS/d in digested manure system and 6.53±0.31, 132.04±3.96 and 640.16±19.92NmL/gVS/d in sewage sludge system during second generation incubation. Meanwhile the model could not fit well in granular sludge system, while the rate of formate methanation was faster than from H2/CO2 and acetate. Considering both the kinetic results and microbial assay we could conclude that H2/CO2 methanation was the fastest methanogenic step in digested manure and sewage sludge system with Methanomicrobiales as dominant methanogens, while granular sludge with Methanobacteriales as dominant methanogens contributed to the fastest formate methanation. PMID:27423547

  13. Kinetics of Exchange Between Zero-, One-, and Two-Hydrogen-Bonded States of Methyl and Ethyl Acetate in Methanol

    PubMed Central

    Chuntonov, Lev; Pazos, Ileana M.; Ma, Jianqiang; Gai, Feng

    2015-01-01

    It has recently been shown that the ester carbonyl stretching vibration can be used as a sensitive probe of local electrostatic field in molecular systems. To further characterize this vibrational probe and extend its potential applications, we studied the kinetics of chemical exchange between differently hydrogen-bonded (H-bonded) ester carbonyl groups of methyl acetate (MA) and ethyl acetate (EA) in methanol. We found that while both MA and EA can form zero, one, or two H-bonds with the solvent, the population of the 2hb state in MA is significantly smaller than that in EA. Using a combination of linear and non-linear infrared measurements and numerical simulations, we further determined the rate constants for the exchange between these differently H-bonded states. We found that for MA the chemical exchange reaction between the two dominant states (i.e., 0hb and 1hb states) has a relaxation rate constant of 0.14 ps−1, whereas for EA the three-state chemical exchange reaction occurs in a predominantly sequential manner with the following relaxation rate constants: 0.11 ps−1 for exchange between 0hb and 1hb states, 0.12 ps−1 for exchange between 1hb and 2hb states. PMID:25738661

  14. Crystal structure of 3-acet-oxy-2-methyl-benzoic acid.

    PubMed

    Saranya, Matheswaran; Subashini, Annamalai; Arunagiri, Chidambaram; Muthiah, Packianathan Thomas

    2015-07-01

    In the title mol-ecule, C10H10O4, the carb-oxy-lic acid group is twisted by 11.37 (15)° from the plane of the benzene ring and the acet-oxy group is twisted from this plane by 86.60 (17)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers with the expected R 2 (2)(8) graph-set motif. PMID:26279915

  15. [Concentrations and acidity contributions of acetate and formate in precipitation at 14 stations of China].

    PubMed

    He, Xiao-huan; Xu, Xiao-bin; Yu, Xiao-lan; Tang, Jie

    2010-04-01

    To investigate the concentrations of organic acids in precipitation in China and their contributions to the total acidity of precipitation, samples were taken at 14 stations of regional representativeness in 2007 and analyzed for acetate and formate using ion chromatography. In this paper, data of acetate and formate in precipitation at 14 stations are presented, wet depositions of these organic acids are calculated, and contributions of them to the total free acidity (TFA) of precipitation are estimated. Based on the measurements, the mean concentrations of formate at different stations were in the range of 0.96-3.43 micromol/L, and those of acetate in the range of 0-5.13 micromol/L, close to the levels at remote sites in other countries and at the lower ends of concentration ranges from previous measurements in China. Comparisons indicate that the concentrations of the organic acids at remote sites are lower than those at sites in the vicinity of urban areas. The annual wet depositions of formate and acetate were estimated to be in the ranges of 0.38-4.18 mmol/(m2 x a) and 0.06-5.87 mmol/(m2 x a), respectively, with larger depositions in southern China and smaller depositions in northern China. The relative contributions of the two organic acids to the TFA of precipitation were estimated to be in the range of 0.02%-51.6%, with an overall average of 2.95%. This suggests that although acid rain in China is mainly caused by emissions of sulfur and nitrogen oxides, organic acids can significantly contribute to the acidification of precipitation in some regions and during some periods, hence need to be included in observational studies of acid rain. PMID:20527162

  16. First European Report of Social Wasps Trapped in Response to Acetic acid, Isobutanol, 2-Methyl-2-propanol, and Heptyl butyrate in Tests Conducted in Hungary

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Five species of social wasps were captured in trapping tests in Hungary that evaluated the attractiveness of acetic acid, isobutanol, 2-methyl-2-propanol, and heptyl butyrate to social wasps. Both Vespula vulgaris (L.) and Vespula germanica (Fabr.), were captured in traps baited with isobutanol, t...

  17. Trapping hop looper moths, Hypena humuli Harris (Lepidoptera: Erebidae), in hop yards in Washington State with acetic acid and 3-methyl-1-butanol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hop looper moths, Hypena humuli Harris, in commercial hop yards (Humulus lupulus L.) were captured in traps baited with a combination of acetic acid plus 3-methyl-1-butanol (AAMB). The two chemicals were synergistic in attracting hop looper moths; in a comparison of the lure chemicals, most moths we...

  18. Macroscopic and microscopic study of 1-ethyl-3-methyl-imidazolium acetate-DMSO mixtures.

    PubMed

    Radhi, Asanah; Le, Kim Anh; Ries, Michael E; Budtova, Tatiana

    2015-01-29

    Macroscopic (steady-state viscosity, density) and microscopic (NMR chemical shifts, (1)H NMR relaxation times, and diffusion) properties of the 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc])-dimethyl sulfoxide (DMSO) mixture were studied in detail as a function of DMSO molar fraction at various temperatures. Temperature dependencies were used to calculate the activation energies. NMR results indicate that at low molar fraction of DMSO (<0.4), it weakly associates with the cation and in doing so disrupts the strong ion-ion association that exists in the pure ionic liquid. Stokes-Einstein equation, which linearly correlates the diffusion coefficient of a spherical molecule and macroscopic viscosity, was shown to work well for the [EMIM][OAc]-DMSO mixture. The influence of DMSO on the "anomalous" diffusion in [EMIM][OAc] ("quick" cation vs "slow" anion) was investigated; it was demonstrated that DMSO makes the cation diffusion slower. All parameters studied showed relatively small deviations from the ideal mixing rule behavior (from 20% to 50% difference between experimental and theoretically predicted results), confirming weak interactions between the components. PMID:25565058

  19. Diffusion of 1-ethyl-3-methyl-imidazolium acetate in glucose, cellobiose, and cellulose solutions.

    PubMed

    Ries, Michael E; Radhi, Asanah; Keating, Alice S; Parker, Owen; Budtova, Tatiana

    2014-02-10

    Solutions of glucose, cellobiose and microcrystalline cellulose in the ionic liquid 1-ethyl-3-methyl-imidazolium ([C2mim][OAc]) have been examined using pulsed-field gradient (1)H NMR. Diffusion coefficients of the cation and anion across the temperature range 20-70 °C have been determined for a range of concentrations (0-15% w/w) of each carbohydrate in [C2mim][OAc]. These systems behave as an "ideal mixture" of free ions and ions that are associated with the carbohydrate molecules. The molar ratio of carbohydrate OH groups to ionic liquid molecules, α, is the key parameter in determining the diffusion coefficients of the ions. Master curves for the diffusion coefficients of cation, anion and their activation energies are generated upon which all our data collapses when plotted against α. Diffusion coefficients are found to follow an Arrhenius type behavior and the difference in translational activation energy between free and associated ions is determined to be 9.3 ± 0.9 kJ/mol. PMID:24405090

  20. Diffusion of 1-Ethyl-3-methyl-imidazolium Acetate in Glucose, Cellobiose, and Cellulose Solutions

    PubMed Central

    2014-01-01

    Solutions of glucose, cellobiose and microcrystalline cellulose in the ionic liquid 1-ethyl-3-methyl-imidazolium ([C2mim][OAc]) have been examined using pulsed-field gradient 1H NMR. Diffusion coefficients of the cation and anion across the temperature range 20–70 °C have been determined for a range of concentrations (0–15% w/w) of each carbohydrate in [C2mim][OAc]. These systems behave as an “ideal mixture” of free ions and ions that are associated with the carbohydrate molecules. The molar ratio of carbohydrate OH groups to ionic liquid molecules, α, is the key parameter in determining the diffusion coefficients of the ions. Master curves for the diffusion coefficients of cation, anion and their activation energies are generated upon which all our data collapses when plotted against α. Diffusion coefficients are found to follow an Arrhenius type behavior and the difference in translational activation energy between free and associated ions is determined to be 9.3 ± 0.9 kJ/mol. PMID:24405090

  1. Photodissociation of methyl formate: Conical intersections, roaming and triple fragmentation

    NASA Astrophysics Data System (ADS)

    Lin, King-Chuen; Tsai, Po-Yu; Chao, Meng-Hsuan; Kasai, Toshio; Lombardi, Andrea; Palazzetti, Federico; Aquilanti, Vincenzo

    2015-12-01

    The photodissociation channels of methyl formate have been extensively investigated by two different advanced experimental techniques, ion imaging and Fourier-Transform-Infrared emission spectroscopy, combined with quantum chemical calculations and molecular dynamics simulations. Our aim is to characterize the role of alternative routes to the conventional transition-state mediated pathway: the roaming and the triple fragmentation processes. The photolysis experiments, carried out at a range of laser wavelengths in the vicinity of the triple fragmentation threshold, beside the simulation of large bunches of classical trajectories with different initial conditions, have shown that both mechanisms share a common path that involves a conical intersection during the relaxation process from the electronic excited state S1 to the ground state S0.

  2. Linalyl Acetate Is Metabolized by Pseudomonas incognita with the Acetoxy Group Intact

    PubMed Central

    Renganathan, V.; Madyastha, K. Madhava

    1983-01-01

    Metabolism of linalyl acetate by Pseudomonas incognita isolated by enrichment culture on the acyclic monoterpene alcohol linalool was studied. Biodegradation of linalyl acetate by this strain resulted in the formation of linalool, linalool-8-carboxylic acid, oleuropeic acid, and Δ5-4-acetoxy-4-methyl hexenoic acid. Cells adapted to linalyl acetate metabolized linalyl acetate-8-aldehyde to linalool-8-carboxylic acid, linalyl acetate-8-carboxylic acid, Δ5-4-acetoxy-4-methyl hexenoic acid, and geraniol-8-carboxylic acid. Resting cell suspensions previously grown with linalyl acetate oxidized linalyl acetate-8-aldehyde to linalyl acetate-8-carboxylic acid, Δ5-4-acetoxy-4-methyl hexenoic acid, and pyruvic acid. The crude cell-free extract (10,000 g of supernatant), obtained from the sonicate of linalyl acetate-grown cells, was shown to contain enzyme systems responsible for the formation of linalyl acetate-8-carboxylic acid and linalool-8-carboxylic acid from linalyl acetate. The same supernatant contained NAD-linked alcohol and aldehyde dehydrogenases involved in the formation of linalyl acetate-8-aldehyde and linalyl acetate-8-carboxylic acid, respectively. On the basis of various metabolites isolated from the culture medium, resting cell experiments, growth and manometric studies carried out with the isolated metabolites as well as related synthetic analogs, and the preliminary enzymatic studies performed with the cell-free extract, a probable pathway for the microbial degradation of linalyl acetate with the acetoxy group intact is suggested. PMID:16346182

  3. Molecular and solid-state structure of methyl [2-(acridin-9-ylimino)-3-( tert-butylamino)-4-oxothiazolidin-5-ylidene]acetate

    NASA Astrophysics Data System (ADS)

    Tomaščiková, Jana; Danihel, Ivan; Böhm, Stanislav; Imrich, Ján; Kristian, Pavol; Potočňák, Ivan; Čejka, Jan; Klika, Karel D.

    2008-03-01

    The molecular and solid-state structures of methyl [2-(acridin-9-ylimino)-3-( tert-butylamino)-4-oxothiazolidin-5-ylidene]acetate ( 4) were determined by X-ray diffraction, 1H NMR, 13C NMR, CI mass spectroscopy and B3LYP calculations using the basis sets 6-31G(d, p), 6-311+G(d, p) and 6-311++G(2d, 2p). In particular, calculations of long-range heteronuclear coupling constants were found to be extraordinarily indicative for the E/ Z configuration of a distal segment. Compound 4 (C 23H 22N 4O 3S, Mr = 434.52) crystallized in the P1¯ space group wherein: a = 11.973(4), b = 12.398(3), c = 15.289(4) Å and α = 85.80(2)°, β = 73.70(3)°, γ = 87.93(2)°, V = 2172.2(11) Å 3, Z = 4 and calculated density = 1.329 g cm -3. The formation of dimers, chains and the crystal packing between the molecules by means of intermolecular hydrogen bonds and π-π interactions between neighboring acridine moieties are discussed. NMR spectral analysis and quantum chemical calculations were found to be in good agreement with the results of the X-ray study. The observation of 4 indicates the dominate role that the N-2 nitrogen of the isothiosemicarbazide intermediate plays in its formation via the reaction of 4-(acridin-9-yl)-1-( tert-butyl)thiosemicarbazide with dimethyl acetylenedicarboxylate (DMAD). This dominance is a result of the steric influences of the substituents on the competing nitrogen atoms.

  4. (6-methyl-2-methylsulfanyl-4-oxo-3,4-dihydro-3-pyrimidinyl)acetic acid and related compounds exhibiting anti-inflammatory activity.

    PubMed

    Jakubkiene, V; Burbuliene, M M; Udrenaite, E; Garaliene, V; Vainilavicius, P

    2002-09-01

    Base-promoted hydrolysis of methyl or ethyl esters 1a-c gave the (6-methyl-2-methylsulfanyl-4-oxo-3,4-dihydro-3-pyrimidinyl)- and (5-ethyl-6-methyl-2-methylsulfanyl-4-oxo-3,4-dihydro-3-pyrimidinyl)acetic acids 2a, b. Under the reaction of ester 1a or acid 2a with nucleophilic reagents a series of derivatives 3-7 of acid 2a were synthesized and evaluated for their anti-inflammatory activity. Most of them were found to be more active than acetylsalicylic acid, and compounds 2a, 6a, b, 7a, f were significantly more active than ibuprofen. The compounds exhibiting the best anti-inflammatory activity showed negative inotropic effect. PMID:12369447

  5. (1)H NMR z-spectra of acetate methyl in stretched hydrogels: quantum-mechanical description and Markov chain Monte Carlo relaxation-parameter estimation.

    PubMed

    Shishmarev, Dmitry; Chapman, Bogdan E; Naumann, Christoph; Mamone, Salvatore; Kuchel, Philip W

    2015-01-01

    The (1)H NMR signal of the methyl group of sodium acetate is shown to be a triplet in the anisotropic environment of stretched gelatin gel. The multiplet structure of the signal is due to the intra-methyl residual dipolar couplings. The relaxation properties of the spin system were probed by recording steady-state irradiation envelopes ('z-spectra'). A quantum-mechanical model based on irreducible spherical tensors formed by the three magnetically equivalent spins of the methyl group was used to simulate and fit experimental z-spectra. The multiple parameter values of the relaxation model were estimated by using a Bayesian-based Markov chain Monte Carlo algorithm. PMID:25486634

  6. Cathodes enhance Corynebacterium glutamicum growth with nitrate and promote acetate and formate production.

    PubMed

    Xafenias, Nikolaos; Kmezik, Cathleen; Mapelli, Valeria

    2016-09-01

    The industrially important Corynebacterium glutamicum can only incompletely reduce nitrate into nitrite which then accumulates and inhibits growth. Herein we report that cathodes can resolve this problem and enhance glucose fermentation and growth by promoting nitrite reduction. Cell growth was inhibited at relatively high potentials but was significant when potentials were more reductive (-1.20V with anthraquinone-2-sulfonate as redox mediator or -1.25V vs. Ag/AgCl). Under these conditions, glucose was consumed up to 6 times faster and acetate was produced at up to 11 times higher yields (up to 1.1mol/mol-glucose). Acetate concentrations are the highest reported so far for C. glutamicum under anaerobic conditions, reaching values up to 5.3±0.3g/L. Herein we also demonstrate for the first time formate production (up to 3.4±0.3g/L) by C. glutamicum under strongly reducing conditions, and we attribute this to a possible mechanism of CO2 bioreduction that was electrochemically triggered. PMID:27235972

  7. Sodium dependence of acetate formation by the acetogenic bacterium Acetobacterium woodii.

    PubMed

    Heise, R; Müller, V; Gottschalk, G

    1989-10-01

    Growth of Acetobacterium woodii on fructose was stimulated by Na+; this stimulation was paralleled by a shift of the acetate-fructose ratio from 2.1 to 2.7. Growth on H2-CO2 or on methanol plus CO2 was strictly dependent on the presence of sodium ions in the medium. Acetate formation from formaldehyde plus H2-CO by resting cells required Na+, but from methanol plus H2-CO did not. This is analogous to H2-CO2 reduction to methane by Methanosarcina barkeri, which involves a sodium pump (V. Müller, C. Winner, and G. Gottschalk, Eur. J. Biochem. 178:519-525, 1988). This suggests that the reduction of methylenetetrahydrofolate to methyltetrahydrofolate is the Na+-requiring reaction. A sodium gradient (Na+ out/Na+ in = 32, delta pNa = -91 mV) was built up when resting cells of A. woodii were incubated under H2-CO2. Acetogenesis was inhibited when the delta pNa was dissipated by monensin. PMID:2507527

  8. Insights into the mechanistic photodissociation of methyl formate

    SciTech Connect

    Cui Ganglong; Zhang Feng; Fang Weihai

    2010-01-21

    In this work, we studied the photodissociation dynamics of methyl formate (CH{sub 3}OC(O)H) using state-of-the-art multireference configuration interaction with single and double excitation and the complete active space self-consistent field methods. It was found that the direct {alpha}-C-O bond cleavage in the first excited singlet state (S{sub 1}) is the dominant dissociation channel, consistent with the recent experiment [S. H. Lee, J. Chem. Phys. 129, 194304 (2008)]. This cleavage mechanism is different from that for aldehydes/ketones where it occurs in the lowest triplet state (T{sub 1}) as a result of the S{sub 1}{yields}T{sub 1} intersystem crossing. On the basis of comparison to the {alpha}-bond fission in the asymmetrically substituted aliphatic carbonyl compounds studied previously, we suggest the photolytic reaction of CH{sub 3}OC(O)H as a special type of Norrish type I reaction.

  9. Global gene expression analysis of glucose overflow metabolism in Escherichia coli and reduction of aerobic acetate formation.

    PubMed

    Veit, Andrea; Polen, Tino; Wendisch, Volker F

    2007-02-01

    During aerobic growth on glucose, Escherichia coli produces acetate in the so-called overflow metabolism. DNA microarray analysis was used to determine the global gene expression patterns of chemostat cultivations of E. coli MG1655 that were characterized by different acetate formation rates during aerobic growth on glucose. A correlation analysis identified that expression of ten genes (sdhCDAB, sucB, sucC, acnB, lpdA, fumC and mdh) encoding the TCA cycle enzymes succinate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinyl-CoA synthetase, aconitase, fumarase and malate dehydrogenase, respectively, and of the acs-yjcH-actP operon for acetate utilization correlated negatively with acetate formation. Relieving transcriptional control of the sdhCDAB-b0725-sucABCD operon by chromosomal promoter exchange mutagenesis yielded a strain with increased specific activities of the TCA cycle enzymes succinate dehydrogenase, alpha-ketoglutarate dehydrogenase and succinyl-CoA synthetase, which are encoded by this operon. The resulting strain produced less acetate and directed more carbon towards carbon dioxide formation than the parent strain MG1655 while maintaining high growth and glucose consumption rates. PMID:17273855

  10. Formation of methyl mercury in an aquatic macrophyte.

    PubMed

    Göthberg, Agneta; Greger, Maria

    2006-12-01

    In the nature, inorganic forms of mercury (Hg) may be transformed to the organic, very toxic, methyl-Hg. Occasionally methyl-Hg has been detected in plants, also so in the aquatic macrophyte water spinach (Ipomoea aquatica), which is a popular vegetable in tropical regions. The objectives of this study were to investigate if methyl-Hg is formed and/or degraded in water spinach. Water spinach plants were exposed to inorganic Hg via spiked soil or spiked nutrient solution. Tests were performed in a climate chamber and in experimental units, one for each individual plant, that were equipped with separated shoot and root compartments. Plant tissues were analysed for total- and methyl-Hg. The results showed that methyl-Hg was accumulated in water spinach, especially in young metabolically active parts, when exposed to external inorganic Hg, even at sterilized conditions. Results also showed that methyl-Hg was formed in water spinach in the absence of external Hg, i.e., during recovery in a not Hg-spiked medium following after HgCl(2)-exposure. There was however, no sign of demethylation. Summarizing, most of the Hg that is taken up by the plants is bound in the roots, but of the comparatively small amounts of Hg that reach the young growing shoots, a part will be methylated. Since the young shoots of this plant make a delicious and very appreciated vegetable, Hg in I. aquatica may contribute to human health problems. PMID:16872659

  11. Rapid test for acetyl-methyl-carbinol formation by Enterobacteriaceae.

    PubMed Central

    Qadri, S M; Nichols, C W; Qadri, S G; Villarreal, A

    1978-01-01

    A modified Voges-Proskauer test is described which distinguishes within 4 to 8 hours between organisms that can produce acetyl-methyl-carbinol (acetoin) from glucose fermentation and those that cannot. PMID:363745

  12. Rapid test for acetyl-methyl-carbinol formation by Enterobacteriaceae.

    PubMed

    Qadri, S M; Nichols, C W; Qadri, S G; Villarreal, A

    1978-10-01

    A modified Voges-Proskauer test is described which distinguishes within 4 to 8 hours between organisms that can produce acetyl-methyl-carbinol (acetoin) from glucose fermentation and those that cannot. PMID:363745

  13. 17α-Acet­oxy-11β-hy­droxy-6α-methyl­pregn-4-ene-3,20-dione

    PubMed Central

    Yousuf, Sammer; Bano, Saira; Choudhary, M. Iqbal

    2012-01-01

    The title compound, C24H34O5, a fungal-transformed metabolite of the injecta­ble contraceptive medroxyprogesterone acetate, consists of four fused rings (A, B, C and D; steroid labelling). Ring A exists in a half-chair conformation while trans-fused rings B and C adopt chair conformations. The five-membered ring D adopts an envelope conformation with the C atom bound to the methyl group at the flap. In the crystal, adjacent mol­ecules are linked by O—H⋯O and C—H⋯O hydrogen bonds, forming infinite chains along the a axis. PMID:22807835

  14. (2,3,4,4-Tetramethylcyclopentyl)methyl acetate, a sex pheromone from the obscure mealybug: first example of a new structural class of monoterpenes.

    PubMed

    Millar, Jocelyn G; Midland, Sharon L; McElfresh, J Steven; Daane, Kent M

    2005-12-01

    The sex pheromone of the obscure mealybug, Pseudococcus viburni, consists of (1R*,2R*,3S*)-(2,3,4,4-tetramethylcyclopentyl)methyl acetate, the first example of a new monoterpenoid structural motif in which the two isoprene units forming the carbon skeleton are joined by 2'-2 and 3'-4 connections rather than the usual 1'-4, head-to-tail connections. This highly irregular terpenoid structure, and the irregular terpenoid structures of related mealybug species, suggest that these insects may have unique terpenoid biosynthetic pathways. PMID:16283090

  15. The millimeter and submillimeter laboratory spectrum of methyl formate in its ground symmetric torsional state

    NASA Technical Reports Server (NTRS)

    Plummer, G. M.; Herbst, E.; De Lucia, F.; Blake, G. A.

    1984-01-01

    Over 200 rotational lines of methyl formate in its ground (v sub t = 0), symmetric (A) torsional state have been measured in the frequency range 140-550 GHz. Analysis of these and lower frequency transitions permits accurate prediction (below 0.1 MHz) of over 10,000 transitions at frequencies below 600 GHz with angular momentum J lower than 50. The measured spectral lines have permitted identification of over 100 new methyl formate lines in Orion.

  16. Modeling the Behavior of Formate, Acetate, and Carbon Dioxide in Water/Steam Cycles

    SciTech Connect

    Gruszkiewicz, Miroslaw {Mirek} S; Palmer, Donald

    2004-01-01

    Organic substances persist in high-temperature aqueous environments for varying periods of tiem depending on temperature, pH, contact with solid surfaces, and other factors. Since carboxylic acids and CO{sub 2} affect the pH and can potentially play specific roles in the promotion of inhibition of turbine corrosion, it is important to be able to predict the amounts of these substances that are transferred to steam and the composition of the early condensate as a function of condesnation ratio for various boiler chemistries. Such predictions can only be made using a speciated model including all the solutes. Example calculations for AVT and OT chemistry show complex relationships between early condensate enrichment ratios and boiler pressure, boiler water composition, and condensation ratio. Even small amounts of sodium and chloride below 0.1 {mu}g {center_dot} kg{sup -1} in the steam are relevant to early condensate pH and carboxylic acid concentration. The calculations show that the enrichment of the early condensate relative to steam is typically 10 times greater for formate than for acetate.

  17. A spectroscopic study on the formation of Cm(III) acetate complexes at elevated temperatures.

    PubMed

    Fröhlich, Daniel R; Skerencak-Frech, Andrej; Panak, Petra J

    2014-03-14

    The complexation of Cm(III) with acetate is studied by time resolved laser fluorescence spectroscopy (TRLFS) as a function of ionic strength, ligand concentration, temperature and background electrolyte (NaClO4, NaCl and CaCl2 solution). The speciation of Cm(III) is determined by peak deconvolution of the emission spectra. To obtain the thermodynamic stability constants (log K) for the formation of [Cm(Ac)n](3-n) (n = 1-3), the experimental data are extrapolated to zero ionic strength according to the specific ion interaction theory (SIT). The results show a continuous increase of the stability constants with increasing temperature (20-90 °C). The standard reaction enthalpies and entropies (ΔrH, ΔrS) of the respective reactions are derived from the integrated Van't Hoff equation. The results show that all complexation steps are endothermic and thus entropy driven (ΔrH and ΔrS > 0). PMID:24448229

  18. Corrosion resistance of siloxane-poly(methyl methacrylate) hybrid films modified with acetic acid on tin plate substrates: Influence of tetraethoxysilane addition

    NASA Astrophysics Data System (ADS)

    Kunst, S. R.; Cardoso, H. R. P.; Oliveira, C. T.; Santana, J. A.; Sarmento, V. H. V.; Muller, I. L.; Malfatti, C. F.

    2014-04-01

    The aim of this paper is to study the corrosion resistance of hybrid films. Tin plate was coated with a siloxane-poly (methyl methacrylate) (PMMA) hybrid film prepared by sol-gel route with covalent bonds between the organic (PMMA) and inorganic (siloxane) phases obtained by hydrolysis and polycondensation of 3-(trimethoxysilylpropyl) methacrylate (TMSM) and polymerization of methyl methacrylate (MMA) using benzoyl peroxide (BPO) as a thermic initiator. Hydrolysis reactions were catalyzed by acetic acid solution avoiding the use of chlorine or stronger acids in the film preparation. The effect of the addition of tetraethoxysilane (TEOS) on the protective properties of the film was evaluated. The hydrophobicity of the film was determined by contact angle measurements, and the morphology was evaluated by scanning electron microscopy (SEM) and profilometry. The local nanostructure was investigated by Fourier transform infrared spectroscopy (FT-IR). The electrochemical behavior of the films was assessed by open circuit potential monitoring, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements in a 0.05 M NaCl solution. The mechanical behavior was evaluated by tribology. The results highlighted that the siloxane-PMMA hybrid films modified with acetic acid are promising anti-corrosive coatings that acts as an efficient diffusion barrier, protecting tin plates against corrosion. However, the coating properties were affected by the TEOS addition, which contributed for the thickness increase and irregular surface coverage.

  19. Crystal structure of ethyl 2-[2-(4-methyl­benzo­yl)-5-p-tolyl-1H-imidazol-1-yl]acetate

    PubMed Central

    Prabha, E. Arockia Jeya Yasmi; Kumar, S. Suresh; Padala, Anil K.; Ahmed, Qazi Naveed; Athimoolam, S.

    2016-01-01

    In the title compound, C22H22N2O3, the plane of the five-membered ring is oriented at dihedral angles of 45.4 (1) and 52.5 (1)° to the phenyl rings. Furthermore, this ring makes an angle of 85.2 (2)° with the plane of the ethyl acetate substituent. The mol­ecular structure is affected by an intra­molecular C—H⋯O hydrogen bond between an H atom from the p-tolyl group and the carbonyl O atom of the acetate. The methyl group of the ethyl acetate residue is disordered over two sites with equal occupancies. The crystal structure features inter­molecular C—H⋯O and C—H⋯N inter­actions. One of the C—H⋯O hydrogen bonds forms a C(5) chain motif extending along the a axis. In addition, C—H⋯N contacts form inversion dimers with R 2 2(12) ring motifs, linking the imidazole ring system to the benzene ring of the p-tolyl substituent. PMID:27006805

  20. Crystal structure of ethyl 2-[2-(4-methyl-benzo-yl)-5-p-tolyl-1H-imidazol-1-yl]acetate.

    PubMed

    Prabha, E Arockia Jeya Yasmi; Kumar, S Suresh; Padala, Anil K; Ahmed, Qazi Naveed; Athimoolam, S

    2016-03-01

    In the title compound, C22H22N2O3, the plane of the five-membered ring is oriented at dihedral angles of 45.4 (1) and 52.5 (1)° to the phenyl rings. Furthermore, this ring makes an angle of 85.2 (2)° with the plane of the ethyl acetate substituent. The mol-ecular structure is affected by an intra-molecular C-H⋯O hydrogen bond between an H atom from the p-tolyl group and the carbonyl O atom of the acetate. The methyl group of the ethyl acetate residue is disordered over two sites with equal occupancies. The crystal structure features inter-molecular C-H⋯O and C-H⋯N inter-actions. One of the C-H⋯O hydrogen bonds forms a C(5) chain motif extending along the a axis. In addition, C-H⋯N contacts form inversion dimers with R 2 (2)(12) ring motifs, linking the imidazole ring system to the benzene ring of the p-tolyl substituent. PMID:27006805

  1. Uranyl acetate induces gel phase formation in model lipid and biological membranes.

    PubMed Central

    Caffrey, M; Morris, S J; Feigenson, G W

    1987-01-01

    The effect of uranyl acetate on the mesomorphic phase state of lipids in model membranes as well as in isolated biological membranes has been examined. As little as 0.8 mM (0.03% [wt/vol]) uranyl acetate induces a liquid crystal-to-gel phase transformation in egg phosphatidic acid, bovine brain phosphatidylserine, and in lysed chromaffin granule membranes. These results along with others in the literature indicate that the uranyl acetate used in samples for electron microscopy could alter membrane morphology. Images FIGURE 1 FIGURE 1 FIGURE 1 PMID:3651563

  2. Biofilm formation and indole-3-acetic acid production by two rhizospheric unicellular cyanobacteria.

    PubMed

    Ahmed, Mehboob; Stal, Lucas J; Hasnain, Shahida

    2014-08-01

    Microorganisms that live in the rhizosphere play a pivotal role in the functioning and maintenance of soil ecosystems. The study of rhizospheric cyanobacteria has been hampered by the difficulty to culture and maintain them in the laboratory. The present work investigated the production of the plant hormone indole-3-acetic acid (IAA) and the potential of biofilm formation on the rhizoplane of pea plants by two cyanobacterial strains, isolated from rice rhizosphere. The unicellular cyanobacteria Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 that were isolated from a rice rhizosphere, were investigated. Production of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 was measured under experimental conditions (pH and light). The bioactivity of the cyanobacterial auxin was demonstrated through the alteration of the rooting pattern of Pisum sativum seedlings. The increase in the concentration of L-tryptophan and the time that this amino acid was present in the medium resulted in a significant enhancement of the synthesis of IAA (r > 0.900 at p = 0.01). There was also a significant correlation between the concentration of IAA in the supernatant of the cyanobacteria cultures and the root length and number of the pea seedlings. Observations made by confocal laser scanning microscopy revealed the presence of cyanobacteria on the surface of the roots and also provided evidence for the penetration of the cyanobacteria in the endorhizosphere. We show that the synthesis of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 occurs under different environmental conditions and that the auxin is important for the development of the seedling roots and for establishing an intimate symbiosis between cyanobacteria and host plants. PMID:24705871

  3. Effect of acetate upon the formation of acetoin in Klebsiella and Enterobacter and it possible practical application in a rapid voges-proskauer test.

    PubMed

    Bryn, K; Ulstrup, J C; Stormer, F C

    1973-03-01

    Acetate stimulates the formation of acetoin during 1-h incubation of Voges-Proskauer-positive strains of Klebsiella and Enterobacter. Of these organisms, 124 of 126 strains were recognized as positive in the presence of acetate, and 106 were recognized as positive in its absence. PMID:4572901

  4. The adsorption of methyl methacrylate and vinyl acetate polymers on α-quartz surface: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Yan, Lijing; Yang, Yan; Jiang, Hui; Zhang, Bingjian; Zhang, Hui

    2016-01-01

    The molecular dynamics simulation was used to investigate the adsorption of polymethyl methacrylate (PMMA) and polyvinyl acetate (PVA), the commonly used surface coating materials, on α-quartz surface. The objective is to understand the interactions between quartz surface and polymers. The results clearly show adsorption of both polymers onto the quartz surface. Carbonyl group plays a significant role in the adsorption process. The adsorption energies of PMMA and PVA on α-quartz surface did not show significant difference, however, more hydrogen bonds were observed on the PVA/quartz system than PMMA/quartz. These observations might offer some insights on the polymer-quartz adhesion and its failure mechanism.

  5. Synthesis, and anticonvulsant activity of new amides derived from 3-methyl- or 3-ethyl-3-methyl-2,5-dioxo-pyrrolidin-1-yl-acetic acids.

    PubMed

    Obniska, Jolanta; Rapacz, Anna; Rybka, Sabina; Góra, Małgorzata; Kamiński, Krzysztof; Sałat, Kinga; Żmudzki, Paweł

    2016-04-15

    This paper describes the synthesis of the library of 22 new 3-methyl- and 3-ethyl-3-methyl-2,5-dioxo-pyrrolidin-1-yl-acetamides as potential anticonvulsant agents. The maximal electroshock (MES) and the subcutaneous pentylenetetrazole (scPTZ) seizure models were used for screening all the compounds. The 6Hz model of pharmacoresistant limbic seizures was applied for studying selected derivatives. Six amides were chosen for pharmacological characterization of their antinociceptive activity in the formalin model of tonic pain as well as local anesthetic activity was assessed in mice. The pharmacological data indicate on the broad spectra of activity across the preclinical seizure models. Compounds 10 (ED50=32.08mg/kg, MES test) and 9 (ED50=40.34mg/kg, scPTZ test) demonstrated the highest potency. These compounds displayed considerably better safety profiles than clinically relevant antiepileptic drugs phenytoin, ethosuximide, or valproic acid. Several molecules showed antinociceptive and local anesthetic properties. The in vitro radioligand binding studies demonstrated that the influence on the sodium and calcium channels may be one of the essential mechanisms of action. PMID:26970661

  6. Formate, acetate, and propionate as substrates for sulfate reduction in sub-arctic sediments of Southwest Greenland.

    PubMed

    Glombitza, Clemens; Jaussi, Marion; Røy, Hans; Seidenkrantz, Marit-Solveig; Lomstein, Bente A; Jørgensen, Bo B

    2015-01-01

    Volatile fatty acids (VFAs) are key intermediates in the anaerobic mineralization of organic matter in marine sediments. We studied the role of VFAs in the carbon and energy turnover in the sulfate reduction zone of sediments from the sub-arctic Godthåbsfjord (SW Greenland) and the adjacent continental shelf in the NE Labrador Sea. VFA porewater concentrations were measured by a new two-dimensional ion chromatography-mass spectrometry method that enabled the direct analysis of VFAs without sample pretreatment. VFA concentrations were low and surprisingly constant (4-6 μmol L(-1) for formate and acetate, and 0.5 μmol L(-1) for propionate) throughout the sulfate reduction zone. Hence, VFAs are turned over while maintaining a stable concentration that is suggested to be under a strong microbial control. Estimated mean diffusion times of acetate between neighboring cells were <1 s, whereas VFA turnover times increased from several hours at the sediment surface to several years at the bottom of the sulfate reduction zone. Thus, diffusion was not limiting the VFA turnover. Despite constant VFA concentrations, the Gibbs energies (ΔGr) of VFA-dependent sulfate reduction decreased downcore, from -28 to -16 kJ (mol formate)(-1), -68 to -31 kJ (mol acetate)(-1), and -124 to -65 kJ (mol propionate)(-1). Thus, ΔGr is apparently not determining the in-situ VFA concentrations directly. However, at the bottom of the sulfate zone of the shelf station, acetoclastic sulfate reduction might operate at its energetic limit at ~ -30 kJ (mol acetate)(-1). It is not clear what controls VFA concentrations in the porewater but cell physiological constraints such as energetic costs of VFA activation or uptake could be important. We suggest that such constraints control the substrate turnover and result in a minimum ΔGr that depends on cell physiology and is different for individual substrates. PMID:26379631

  7. 1-(2-Methyl-5-nitro-1H-imidazol-1-yl)propan-2-yl acetate.

    PubMed

    Shahid, Hafiz Abdullah; Hussain, Ejaz; Jahangir, Sajid; Yousuf, Sammer

    2014-03-01

    In the title compound, C9H13N3O4, an ester of the anti-infection drug secnidazole, the dihedral angle between the nitro-imidazole mean plane (r.m.s. deviation = 0.028 Å) and the pendant acetate group is 43.17 (11)°. In the crystal, inversion dimers linked by pairs of C-H⋯O inter-actions generate R 2 (2)(10) loops and further C-H⋯O hydrogen bonds link the dimers into [100] chains. Weak aromatic π-π stacking inter-actions with a centroid-centroid distance of 3.7623 (11) Å are also observed. PMID:24765001

  8. 1-(2-Methyl-5-nitro-1H-imidazol-1-yl)propan-2-yl acetate

    PubMed Central

    Shahid, Hafiz Abdullah; Hussain, Ejaz; Jahangir, Sajid; Yousuf, Sammer

    2014-01-01

    In the title compound, C9H13N3O4, an ester of the anti-infection drug secnidazole, the dihedral angle between the nitro­imidazole mean plane (r.m.s. deviation = 0.028 Å) and the pendant acetate group is 43.17 (11)°. In the crystal, inversion dimers linked by pairs of C—H⋯O inter­actions generate R 2 2(10) loops and further C—H⋯O hydrogen bonds link the dimers into [100] chains. Weak aromatic π–π stacking inter­actions with a centroid–centroid distance of 3.7623 (11) Å are also observed. PMID:24765001

  9. Preliminary Work to Alma: Submillimeter Wave Spectroscopy of ^{18}O and D Species of Methyl Formate

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R.; Huet, T. R.; Møllendal, H.; Guillemin, J.-C.; Demyk, K.; Carvajal, M.; Kleiner, I.; Coudert, L. H.

    2009-06-01

    New radiotelescopes, working in the submillimeter range, will be operating in the next few years: ALMA, Herschel, and SOFIA. A large amount of laboratory work is required in order to account for the increased resolution and accuracy needed to analyze the numerous data which will be obtained with these new instruments. There is a strong interest of the astrophysical community in isotopic species for two main reasons: (i) Their detection provides us with key information about interstellar chemical modeling, especially for complex organic molecules, like methyl formate, as their formation mechanisms is not well understood yet. (ii) They are responsible for a large fraction of U-lines and their assignments are necessary to allow the detection of new species. In this context we continue a systematic study of the isotopic species of methyl formate (HCOOCH_3) initiated with H^{13}COOCH_3. Our next investigation of HCOO^{13}CH_3 allowed us the detection of 500 lines in Orion. The treatment of the data concerning methyl formate is not obvious due to the internal rotation of the methyl group. This treatment is different in case of a symmetric (CH_3) or an asymmetric (CHD_2) rotor part. We will report here on recent results obtained for DCOOCH_3, HCOOCHD_2, HC^{18}OOCH_3, and HCO^{18}OCH_3. [2] Willaert, Møllendal, Alekseev, et al. J. Mol. Struct. 795 (2006) [3] Carvajal, Margules, Tercero, et al. Astron. Astrophys. (2009) in press

  10. Two-dimensional hydrogen-bonded polymers in the crystal structures of the ammonium salts of phen­oxy­acetic acid, (4-fluoro­phen­oxy)acetic acid and (4-chloro-2-methyl­phen­oxy)acetic acid

    PubMed Central

    Smith, Graham

    2014-01-01

    The structures of the ammonium salts of phen­oxy­acetic acid, NH4 +·C8H6O3 −, (I), (4-fluoro­phen­oxy)acetic acid, NH4 +·C8H5FO3 −, (II), and the herbicidally active (4-chloro-2-methyl­phen­oxy)acetic acid (MCPA), NH4 +·C9H8ClO3 −·0.5H2O, (III) have been determined. All have two-dimensional layered structures based on inter-species ammonium N—H⋯O hydrogen-bonding associations, which give core substructures consisting primarily of conjoined cyclic motifs. The crystals of (I) and (II) are isomorphous with the core comprising R 1 2(5), R 1 2(4) and centrosymmetric R 4 2(8) ring motifs, giving two-dimensional layers lying parallel to (100). In (III), the water mol­ecule of solvation lies on a crystallographic twofold rotation axis and bridges two carboxyl O atoms in an R 4 4(12) hydrogen-bonded motif, creating two R 4 3(10) rings, which together with a conjoined centrosymmetric R 4 2(8) ring incorporating both ammonium cations, generate two-dimensional layers lying parallel to (100). No π–π ring associations are present in any of the structures. PMID:25552984

  11. Cu-catalyzed conversion of propargyl acetates to E-α,β-unsaturated amides via ketenimine formation with sulfonyl azides.

    PubMed

    Kumar, Yalla Kiran; Ranjith Kumar, Gadi; Reddy, Maddi Sridhar

    2014-01-17

    The reaction between readily accessible propargyl acetates and sulfonyl azides in the presence of CuI catalyst yields trans-α,β-unsaturated N-tosylamides via N-sulfonyl ketenimine formation followed by a probable 1,3-OAc migration ([3,3]-sigmatropic rearrangement). The reaction is very general, allowing all kinds of substitution, including alkyl, aryl (electron-donating, -withdrawing, and -neutral), heteroaryl, and vinyl groups, on the C-terminal of acrylamide. Also, the method affords the products at ambient temperature with excellent diastereoselectivity in moderate to good yields. PMID:24344764

  12. Escherichia coli W shows fast, highly oxidative sucrose metabolism and low acetate formation.

    PubMed

    Arifin, Yalun; Archer, Colin; Lim, SooA; Quek, Lake-Ee; Sugiarto, Haryadi; Marcellin, Esteban; Vickers, Claudia E; Krömer, Jens O; Nielsen, Lars K

    2014-11-01

    Sugarcane is the most efficient large-scale crop capable of supplying sufficient carbon substrate, in the form of sucrose, needed during fermentative feedstock production. However, sucrose metabolism in Escherichia coli is not well understood because the two most common strains, E. coli K-12 and B, do not grow on sucrose. Here, using a sucrose utilizing strain, E. coli W, we undertake an in-depth comparison of sucrose and glucose metabolism including growth kinetics, metabolite profiling, microarray-based transcriptome analysis, labelling-based proteomic analysis and (13)C-fluxomics. While E. coli W grew comparably well on sucrose and glucose integration of the omics, datasets showed that during growth on each carbon source, metabolism was distinct. The metabolism was generally derepressed on sucrose, and significant flux rearrangements were observed in central carbon metabolism. These included a reduction in the flux of the oxidative pentose phosphate pathway branch, an increase in the tricarboxylic acid cycle flux and a reduction in the glyoxylate shunt flux due to the dephosphorylation of isocitrate dehydrogenase. But unlike growth on other sugars that induce cAMP-dependent Crp regulation, the phosphoenol-pyruvate-glyoxylate cycle was not active on sucrose. Lower acetate accumulation was also observed in sucrose compared to glucose cultures. This was linked to induction of the acetate catabolic genes actP and acs and independent of the glyoxylic shunt. Overall, the cells stayed highly oxidative. In summary, sucrose metabolism was fast, efficient and led to low acetate accumulation making it an ideal carbon source for industrial fermentation with E. coli W. PMID:25125039

  13. Tetrahydrofolate enzyme levels in Acetobacterium woodii and their implication in the synthesis of acetate from CO2.

    PubMed Central

    Tanner, R S; Wolfe, R S; Ljungdahl, L G

    1978-01-01

    Acetate synthesis from CO2 by Acetobacterium woodii may occur as in homoacetate-fermenting clostridia, as indicated by high levels of enzymes of the tetrahydrofolate pathway and by pyruvate-dependent formation of acetate from methyl-B12 and methyltetrahydrofolate. PMID:659361

  14. Tetrahydrofolate enzyme levels in Acetobacterium woodii and their implication in the synthesis of acetate from CO2.

    PubMed

    Tanner, R S; Wolfe, R S; Ljungdahl, L G

    1978-05-01

    Acetate synthesis from CO2 by Acetobacterium woodii may occur as in homoacetate-fermenting clostridia, as indicated by high levels of enzymes of the tetrahydrofolate pathway and by pyruvate-dependent formation of acetate from methyl-B12 and methyltetrahydrofolate. PMID:659361

  15. Formate, acetate, and propionate as substrates for sulfate reduction in sub-arctic sediments of Southwest Greenland

    PubMed Central

    Glombitza, Clemens; Jaussi, Marion; Røy, Hans; Seidenkrantz, Marit-Solveig; Lomstein, Bente A.; Jørgensen, Bo B.

    2015-01-01

    Volatile fatty acids (VFAs) are key intermediates in the anaerobic mineralization of organic matter in marine sediments. We studied the role of VFAs in the carbon and energy turnover in the sulfate reduction zone of sediments from the sub-arctic Godthåbsfjord (SW Greenland) and the adjacent continental shelf in the NE Labrador Sea. VFA porewater concentrations were measured by a new two-dimensional ion chromatography-mass spectrometry method that enabled the direct analysis of VFAs without sample pretreatment. VFA concentrations were low and surprisingly constant (4–6 μmol L−1 for formate and acetate, and 0.5 μmol L−1 for propionate) throughout the sulfate reduction zone. Hence, VFAs are turned over while maintaining a stable concentration that is suggested to be under a strong microbial control. Estimated mean diffusion times of acetate between neighboring cells were <1 s, whereas VFA turnover times increased from several hours at the sediment surface to several years at the bottom of the sulfate reduction zone. Thus, diffusion was not limiting the VFA turnover. Despite constant VFA concentrations, the Gibbs energies (ΔGr) of VFA-dependent sulfate reduction decreased downcore, from −28 to −16 kJ (mol formate)−1, −68 to −31 kJ (mol acetate)−1, and −124 to −65 kJ (mol propionate)−1. Thus, ΔGr is apparently not determining the in-situ VFA concentrations directly. However, at the bottom of the sulfate zone of the shelf station, acetoclastic sulfate reduction might operate at its energetic limit at ~ −30 kJ (mol acetate)−1. It is not clear what controls VFA concentrations in the porewater but cell physiological constraints such as energetic costs of VFA activation or uptake could be important. We suggest that such constraints control the substrate turnover and result in a minimum ΔGr that depends on cell physiology and is different for individual substrates. PMID:26379631

  16. Role of methyl group number on SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NOx conditions

    NASA Astrophysics Data System (ADS)

    Li, L.; Tang, P.; Nakao, S.; Chen, C.-L.; Cocker, D. R., III

    2016-02-01

    Substitution of methyl groups onto the aromatic ring determines the secondary organic aerosol (SOA) formation from the monocyclic aromatic hydrocarbon precursor (SOA yield and chemical composition). This study links the number of methyl groups on the aromatic ring to SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NOx conditions (HC/NO > 10 ppbC : ppb). Monocyclic aromatic hydrocarbons with increasing numbers of methyl groups are systematically studied. SOA formation from pentamethylbenzene and hexamethylbenzene are reported for the first time. A decreasing SOA yield with increasing number of methyl groups is observed. Linear trends are found in both f44 vs. f43 and O / C vs. H / C for SOA from monocyclic aromatic hydrocarbons with zero to six methyl groups. An SOA oxidation state predictive method based on benzene is used to examine the effect of added methyl groups on aromatic oxidation under low-NOx conditions. Further, the impact of methyl group number on density and volatility of SOA from monocyclic aromatic hydrocarbons is explored. Finally, a mechanism for methyl group impact on SOA formation is suggested. Overall, this work suggests that, as more methyl groups are attached on the aromatic ring, SOA products from these monocyclic aromatic hydrocarbons become less oxidized per mass/carbon on the basis of SOA yield or chemical composition.

  17. Acetic Acid Can Catalyze Succinimide Formation from Aspartic Acid Residues by a Concerted Bond Reorganization Mechanism: A Computational Study

    PubMed Central

    Takahashi, Ohgi; Kirikoshi, Ryota; Manabe, Noriyoshi

    2015-01-01

    Succinimide formation from aspartic acid (Asp) residues is a concern in the formulation of protein drugs. Based on density functional theory calculations using Ace-Asp-Nme (Ace = acetyl, Nme = NHMe) as a model compound, we propose the possibility that acetic acid (AA), which is often used in protein drug formulation for mildly acidic buffer solutions, catalyzes the succinimide formation from Asp residues by acting as a proton-transfer mediator. The proposed mechanism comprises two steps: cyclization (intramolecular addition) to form a gem-diol tetrahedral intermediate and dehydration of the intermediate. Both steps are catalyzed by an AA molecule, and the first step was predicted to be rate-determining. The cyclization results from a bond formation between the amide nitrogen on the C-terminal side and the side-chain carboxyl carbon, which is part of an extensive bond reorganization (formation and breaking of single bonds and the interchange of single and double bonds) occurring concertedly in a cyclic structure formed by the amide NH bond, the AA molecule and the side-chain C=O group and involving a double proton transfer. The second step also involves an AA-mediated bond reorganization. Carboxylic acids other than AA are also expected to catalyze the succinimide formation by a similar mechanism. PMID:25588215

  18. Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system

    NASA Astrophysics Data System (ADS)

    Ohtomo, Y.; Ijiri, A.; Ikegawa, Y.; Tsutsumi, M.; Imachi, H.; Uramoto, G.; Hoshino, T.; Morono, Y.; Tanikawa, W.; Hirose, T.; Inagaki, F.

    2013-12-01

    The geological CO2 sequestration into subsurface unmineable oil/gas fields and coal formations has been considered as one of the possible ways to reduce dispersal of anthropogenic greenhouse gasses into the atmosphere. However, feasibility of CO2 injection largely depends on a variety of geological and economical settings, and its ecological consequences have remained largely unpredictable. To address these issues, we developed a new flow-through-type CO2 injection system designated as the 'geobio-reactor system' to examine possible geophysical, geochemical and microbiological impact caused by CO2 injection under in-situ pressure (0-100 MPa) and temperature (0-70°C) conditions. In this study, we investigated Eocene bituminous coal-sandstones in the northwestern Pacific coast, Hokkaido, Japan, using the geobio-reactor system. Anaerobic artificial fluid and CO2 (flow rate: 0.002 and 0.00001 mL/min, respectively) were continuously supplemented into the coal-sand column under the pore pressure of 40 MPa (confined pressure: 41 MPa) at 40°C for 56 days. Molecular analysis of bacterial 16S rRNA genes showed that predominant bacterial components were physically dispersed from coal to sand as the intact form during experiment. Cultivation experiments from sub-sampling fluids indicated that some terrestrial microbes could preserve their survival in subsurface condition. Molecular analysis of archaeal 16S rRNA genes also showed that no methanogens were activated during experiment. We also anaerobically incubated the coal sample using conventional batch-type cultivation technique with a medium for methanogens. After one year of the batch incubation at 20°C, methane could be detected from the cultures except for the acetate-fed culture. The sequence of archaeal 16S rRNA genes via PCR amplification obtained from the H2 plus formate-fed culture was affiliated with a hydrogenotrophic methanogen within the genus Methanobacterium, whereas the methanol plus trimethylamine culture

  19. The laboratory millimeter-wave spectrum of methyl formate in its ground torsional E state

    NASA Technical Reports Server (NTRS)

    Plummer, G. M.; Herbst, E.; De Lucia, F. C.; Blake, G. A.

    1986-01-01

    Over 250 rotational transitions of the internal rotor methyl formate (HCOOCH3) in its ground v(t) = 0 degenerate (E) torsional substate have been measured in the millimeter-wave spectral region. These data and a number of E-state lines identified by several other workers have been analyzed using an extension of the classical principal-axis method in the high barrier limit. The resulting rotational constants allow accurate prediction of the v(t) = 0 E substate methyl formate spectrum below 300 GHz between states with angular momentum J not greater than 30 and rotational energy of not more than 350/cm. The calculated transition frequencies for the E state, when combined with the results of the previous analysis of the ground-symmetric, nondegenerate state, account for over 200 of the emission lines observed toward Orion in a recent survey of the 215-265 GHz band.

  20. Potential biofuel additive from renewable sources--Kinetic study of formation of butyl acetate by heterogeneously catalyzed transesterification of ethyl acetate with butanol.

    PubMed

    Ali, Sami H; Al-Rashed, Osama; Azeez, Fadhel A; Merchant, Sabiha Q

    2011-11-01

    Butyl acetate holds great potential as a sustainable biofuel additive. Heterogeneously catalyzed transesterification of biobutanol and bioethylacetate can produce butyl acetate. This route is eco-friendly and offers several advantages over the commonly used Fischer Esterification. The Amberlite IR 120- and Amberlyst 15-catalyzed transesterification is studied in a batch reactor over a range of catalyst loading (6-12 wt.%), alcohol to ester feed ratio (1:3 to 3:1), and temperature (303.15-333.15K). A butanol mole fraction of 0.2 in the feed is found to be optimum. Amberlite IR 120 promotes faster kinetics under these conditions. The transesterifications studied are slightly exothermic. The moles of solvent sorbed per gram of catalyst decreases (ethanol>butanol>ethyl acetate>butyl acetate) with decrease in solubility parameter. The dual site models, the Langmuir Hinshelwood and Popken models, are the most successful in correlating the kinetics over Amberlite IR 120 and Amberlyst 15, respectively. PMID:21908187

  1. Homogeneous Hydrogenation of CO₂ to Methyl Formate Utilizing Switchable Ionic Liquids

    SciTech Connect

    Yadav, Mahendra; Linehan, John C.; Karkamkar, Abhijeet J.; Van Der Eide, Edwin F.; Heldebrant, David J.

    2014-09-15

    Capture of CO₂ and subsequent hydrogenation allows for base/alcohol-catalyzed conversion of CO₂ to methylformate in one pot. The conversion of CO₂ proceeds via alkylcarbonates, to formate salts and then formate esters, which can be catalyzed by base and alcohol with the only byproduct being water. The system operates at mild conditions (300 psi H₂, 140 °C). Reactivity is strongly influenced by temperature and choice of solvent. In the presence of excess of base (DBU) formate is predominant product while in excess of methanol methyl formate is major product. 110 °C yields formate salts, 140 °C promotes methylformate. The authors acknowledge internal Laboratory Directed Re-search and Development (LDRD) funding from Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the U.S. Department of Energy.

  2. Comprehensive Submillimeter Wave Studies of the Isotopic Species of a Major Weed: Methyl Formate

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R.; Huet, T. R.; Coudert, L. H.; Kleiner, I.; Carvajal, M.; Mollendal, H.; Guillemin, J.-C.

    2010-06-01

    Complex organic molecules are relatively heavy, their maximum absorption is in the millimetric domain at about 300 GHz. But the most abondant, like methyl formate, could be detected in the ISM up to 900 GHz. We will present here the last results obtained about the two 18O and the doubly-deuterated species of methyl formate. This concludes the systematic investigation up to 660 GHz for the mono-substituted isotopic species with either 13C, 18O, or D, which began in 2006. The lines from these isotopic species will certainly be present in the spectra which will be recorded in the next years with the very sensitive telescope ALMA, HERSHEL and SOFIA. The detection of isotopic species is very important for the astrophysical community to improve the interstellar chemical modeling and to understand the formation mechanism of these complex organic molecules. Our interest was also on the theoretical aspects. Like other complex organic molecules, methyl formate displays a large amplitude motion. Here it is the rotation of the methyl group with respect to the rest of the molecule. Theoretical models were developed to reproduce accurately the observed frequencies for large quantum numbers values as J-values as high as 70 could be reached. Similarly the investigation of the doubly-deuterated HCOOCHD_2 was undertaken to test the model developed for mono-deuterated HCOOCH_2D. This work is supported by ANR-08-BLAN-0054 and ANR-08-BLAN-0225. C. Comito, P. Schilke, T. G. Phillips, et al., Astrophys. J. Supp. 156 (2005) 127. L. Margulès, L. H. Coudert, H. Mollendal, et al., J. Mol. Spec. 254 (2009) 55.

  3. THE MICROWAVE SPECTROSCOPY OF METHYL FORMATE IN THE SECOND TORSIONAL EXCITED STATE

    SciTech Connect

    Kobayashi, Kaori; Takamura, Kazunori; Sakai, Yusuke; Tsunekawa, Shozo; Odashima, Hitoshi; Ohashi, Nobukimi

    2013-03-01

    The cis-methyl formate molecule is a well known molecule found in interstellar space. Recently, rotational lines of methyl formate in the first CH{sub 3} torsional excited state were observed in Orion KL and W51e2. It is quite natural to observe methyl formate in even higher vibrational states considering the temperature estimated in Orion KL and W51e2. Maeda et al. reported results on the laboratory spectroscopy of methyl formate including the spectral analysis in its second CH{sub 3} torsional state. Their assignments were limited to a series of a-type R-branch lines and low K{sub a} b-type R-branch transitions, and many assigned lines are excluded in the least-squares analysis. In the present study, we extended the line assignments of both the A- and E-species transitions in the second CH{sub 3} torsional state especially in the frequency region below the 120 GHz region. By combining the present assignments and those made by Maeda et al., 1951 transitions in total for the second CH{sub 3} torsional state, 1096 A-species transitions up to J = 39, and K{sub a} = 15 and 855 E-species transitions up to J = 35 and K{sub a} = 13, were least-squares analyzed by using the pseudo-principal-axis-method Hamiltonian with 42 parameters consisting of rotational, centrifugal distortion, and internal rotational constants in the second CH{sub 3} torsional state. In addition, 1012 transitions out of 1096 A-species transitions could also be least-squares analyzed by using Watson's A-reduced Hamiltonian with 43 parameters, which can serve to calculate the energy levels of the A-species lines of molecules with the CH{sub 3} internal rotation conveniently.

  4. The Microwave Spectroscopy of Methyl Formate in the Second Torsional Excited State

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kaori; Takamura, Kazunori; Sakai, Yusuke; Tsunekawa, Shozo; Odashima, Hitoshi; Ohashi, Nobukimi

    2013-03-01

    The cis-methyl formate molecule is a well known molecule found in interstellar space. Recently, rotational lines of methyl formate in the first CH3 torsional excited state were observed in Orion KL and W51e2. It is quite natural to observe methyl formate in even higher vibrational states considering the temperature estimated in Orion KL and W51e2. Maeda et al. reported results on the laboratory spectroscopy of methyl formate including the spectral analysis in its second CH3 torsional state. Their assignments were limited to a series of a-type R-branch lines and low Ka b-type R-branch transitions, and many assigned lines are excluded in the least-squares analysis. In the present study, we extended the line assignments of both the A- and E-species transitions in the second CH3 torsional state especially in the frequency region below the 120 GHz region. By combining the present assignments and those made by Maeda et al., 1951 transitions in total for the second CH3 torsional state, 1096 A-species transitions up to J = 39, and Ka = 15 and 855 E-species transitions up to J = 35 and Ka = 13, were least-squares analyzed by using the pseudo-principal-axis-method Hamiltonian with 42 parameters consisting of rotational, centrifugal distortion, and internal rotational constants in the second CH3 torsional state. In addition, 1012 transitions out of 1096 A-species transitions could also be least-squares analyzed by using Watson's A-reduced Hamiltonian with 43 parameters, which can serve to calculate the energy levels of the A-species lines of molecules with the CH3 internal rotation conveniently.

  5. Heat stress enhances LTM formation in Lymnaea: role of HSPs and DNA methylation.

    PubMed

    Sunada, Hiroshi; Riaz, Hamza; de Freitas, Emily; Lukowiak, Kai; Swinton, Cayley; Swinton, Erin; Protheroe, Amy; Shymansky, Tamila; Komatsuzaki, Yoshimasa; Lukowiak, Ken

    2016-05-01

    Environmentally relevant stressors alter the memory-forming process in Lymnaea following operant conditioning of aerial respiration. One such stressor is heat. Previously, we found that following a 1 h heat shock, long-term memory (LTM) formation was enhanced. We also had shown that the heat stressor activates at least two heat shock proteins (HSPs): HSP40 and HSP70. Here, we tested two hypotheses: (1) the production of HSPs is necessary for enhanced LTM formation; and (2) blocking DNA methylation prevents the heat stressor-induced enhancement of LTM formation. We show here that the enhancing effect of the heat stressor on LTM formation occurs even if snails experienced the stressor 3 days previously. We further show that a flavonoid, quercetin, which inhibits HSP activation, blocks the enhancing effect of the heat stressor on LTM formation. Finally, we show that injection of a DNA methylation blocker, 5-AZA, before snails experience the heat stressor prevents enhancement of memory formation. PMID:27208033

  6. ASCIZ regulates lesion-specific Rad51 focus formation and apoptosis after methylating DNA damage.

    PubMed

    McNees, Carolyn J; Conlan, Lindus A; Tenis, Nora; Heierhorst, Jörg

    2005-07-01

    Nuclear Rad51 focus formation is required for homology-directed repair of DNA double-strand breaks (DSBs), but its regulation in response to non-DSB lesions is poorly understood. Here we report a novel human SQ/TQ cluster domain-containing protein termed ASCIZ that forms Rad51-containing foci in response to base-modifying DNA methylating agents but not in response to DSB-inducing agents. ASCIZ foci seem to form prior to Rad51 recruitment, and an ASCIZ core domain can concentrate Rad51 in focus-like structures independently of DNA damage. ASCIZ depletion dramatically increases apoptosis after methylating DNA damage and impairs Rad51 focus formation in response to methylating agents but not after ionizing radiation. ASCIZ focus formation and increased apoptosis in ASCIZ-depleted cells depend on the mismatch repair protein MLH1. Interestingly, ASCIZ foci form efficiently during G1 phase, when sister chromatids are unavailable as recombination templates. We propose that ASCIZ acts as a lesion-specific focus scaffold in a Rad51-dependent pathway that resolves cytotoxic repair intermediates, most likely single-stranded DNA gaps, resulting from MLH1-dependent processing of base lesions. PMID:15933716

  7. ASCIZ regulates lesion-specific Rad51 focus formation and apoptosis after methylating DNA damage

    PubMed Central

    McNees, Carolyn J; Conlan, Lindus A; Tenis, Nora; Heierhorst, Jörg

    2005-01-01

    Nuclear Rad51 focus formation is required for homology-directed repair of DNA double-strand breaks (DSBs), but its regulation in response to non-DSB lesions is poorly understood. Here we report a novel human SQ/TQ cluster domain-containing protein termed ASCIZ that forms Rad51-containing foci in response to base-modifying DNA methylating agents but not in response to DSB-inducing agents. ASCIZ foci seem to form prior to Rad51 recruitment, and an ASCIZ core domain can concentrate Rad51 in focus-like structures independently of DNA damage. ASCIZ depletion dramatically increases apoptosis after methylating DNA damage and impairs Rad51 focus formation in response to methylating agents but not after ionizing radiation. ASCIZ focus formation and increased apoptosis in ASCIZ-depleted cells depend on the mismatch repair protein MLH1. Interestingly, ASCIZ foci form efficiently during G1 phase, when sister chromatids are unavailable as recombination templates. We propose that ASCIZ acts as a lesion-specific focus scaffold in a Rad51-dependent pathway that resolves cytotoxic repair intermediates, most likely single-stranded DNA gaps, resulting from MLH1-dependent processing of base lesions. PMID:15933716

  8. Ni/sup II/(dioxo(16)aneN/sub 5/)-induced methane formation from methyl coenzyme M

    SciTech Connect

    Drain, C.M.; Sable, D.B.; Corden, B.B.

    1988-07-13

    A mechanism has been previously proposed for methyl-coenzyme M (H/sub 3/CSCH/sub 2/CH/sub 2/SO/sub 3//sup /minus//) reductase where Ni/sup II/F/sub 430/ is first reduced to NiF/sub 430/, which homolytically cleaves the methyl-coenzyme M to produce methyl-Ni/sup I/F/sub 430/ followed by the protonation of methyl-Ni/sup I/F/sub 430/ to yield CH/sub 4/ and Ni/sup II/F/sub 430/. The role of the nickel ion oxidation state in methyl-coenzyme M catalysis has been examined. It was found that both the mono- and divalent oxidation states of the water soluble Ni (dioxo(16)-aneN/sub 5/), NiL, complex catalyze the methyl-coenzyme M to methane and coenzyme M. Some aqueous solutions of other nickel compounds, e.g. nickel (II) acetate, nickel(II) tetraethylenepentamine, or nickel(II) 1,4,8,11-tetraazacyclotetradecane-5,7-dione, do not convert methyl-coenzyme M to methane under argon or hydrogen. 30 references, 1 figure.

  9. Reversible Carbene Formation in the Ionic Liquid 1-Ethyl-3-Methylimidazolium Acetate by Vaporization and Condensation.

    PubMed

    Kar, Bishnu Prasad; Sander, Wolfram

    2015-12-01

    The role of N-heterocyclic carbenes in the chemistry of ionic liquids based on imidazolium salts has long been discussed. Here, we present experimental evidence that 1-ethyl-3-methylimidazolium-2-ylidene (EMIm) can coexist with its protonated imidazolium cation (EMImH(+) ) at low temperatures. If the vapor of the ionic liquid [EMImH(+) ][AcO(-) ] is trapped in solid argon or nitrogen at 9 K, only acetic acid (AcOH) and the carbene, but no ionic species, are found by IR spectroscopy. This indicates that during the evaporation of [EMImH(+) ][AcO(-) ] proton transfer occurs to form the neutral species. If the vapor of [EMImH(+) ][AcO(-) ] is trapped at 9 K as film in the absence of a host matrix, a solid consisting of EMImH(+) , EMIm, AcO(-) , and AcOH is formed. During warming to room temperature the proton transfer in the solid to form back the IL [EMImH(+) ][AcO(-) ] can be monitored by IR spectroscopy. This clearly demonstrates that evaporation and condensation of the IL [EMImH(+) ][AcO(-) ] results in a double proton transfer, and the carbene EMIm is only metastable even at low temperatures. PMID:26376583

  10. Synthesis and triplex formation of oligonucleotides containing 8-thioxodeoxyadenosine and 5-methyl-2-thiodeoxycytosine.

    PubMed

    Ohkubo, Akihiro; Miyata, Kenichi; Tsunoda, Hirosuke; Seio, Kohji; Sekine, Mitsuo

    2009-01-01

    For more effective DNA triplex formation under neutral conditions, we synthesized triplex-forming oligonucleotides (TFO) containing 8-thioxodeoxyadenine (s(8)A) residues in place of the protonated cytosines (Cs) required for the third base pairing with DNA duplexes. Consequently, it was found that s(8)A exhibited much stronger hybridization ability than C under neutral conditions when four s(8)A bases were arranged in a consecutive sequence. Moreover, we also synthesized TFOs containing 5-methyl-2-thiocytosines and examined their ability of triplex formation. PMID:19749240

  11. Secondary organic aerosol formation and composition from the photo-oxidation of methyl chavicol (estragole)

    NASA Astrophysics Data System (ADS)

    Pereira, K. L.; Hamilton, J. F.; Rickard, A. R.; Bloss, W. J.; Alam, M. S.; Camredon, M.; Muñoz, A.; Vásquez, M.; Borrás, E.; Ródenas, M.

    2013-12-01

    The increasing demand for palm oil for uses in biofuel and food products is leading to rapid expansion of oil palm agriculture. Methyl chavicol (also known as estragole and 1-allyl-4-methoxybenzene) is an oxygenated biogenic volatile organic compound that was recently identified as the main floral emission from an oil palm plantation in Malaysian Borneo. The emissions of methyl chavicol observed may impact regional atmospheric chemistry, but little is known of its ability to form secondary organic aerosol (SOA). The photo-oxidation of methyl chavicol was investigated at the European Photoreactor chamber as a part of the atmospheric chemistry of methyl chavicol (ATMECH) project. Aerosol samples were collected using a particle into liquid sampler (PILS) and analysed offline using an extensive range of instruments including; high performance liquid chromatography mass spectrometry (HPLC-ITMS), high performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-QTOFMS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The SOA yield was determined as 18-29% depending on initial precursor (VOC : NOx) mixing ratios. In total, 59 SOA compounds were observed and the structures of 10 compounds have been identified using high resolution tandem mass spectrometry. The addition of hydroxyl and/or nitro functional groups to the aromatic ring appears to be an important mechanistic pathway for aerosol formation. This results in the formation of compounds with both low volatility and high O : C ratios, where functionalisation rather than fragmentation is mainly observed as a~result of the stability of the ring. The SOA species observed can be characterized as semi-volatile to low volatile oxygenated organic aerosol (SVOOA and LVOOA) components and therefore may be important in aerosol formation and growth.

  12. Secondary organic aerosol formation and composition from the photo-oxidation of methyl chavicol (estragole)

    NASA Astrophysics Data System (ADS)

    Pereira, K. L.; Hamilton, J. F.; Rickard, A. R.; Bloss, W. J.; Alam, M. S.; Camredon, M.; Muñoz, A.; Vázquez, M.; Borrás, E.; Ródenas, M.

    2014-06-01

    The increasing demand for palm oil for uses in biofuel and food products is leading to rapid expansion of oil palm agriculture. Methyl chavicol (also known as estragole and 1-allyl-4-methoxybenzene) is an oxygenated biogenic volatile organic compound (VOC) that was recently identified as the main floral emission from an oil palm plantation in Malaysian Borneo. The emissions of methyl chavicol observed may impact regional atmospheric chemistry, but little is known of its ability to form secondary organic aerosol (SOA). The photo-oxidation of methyl chavicol was investigated at the European Photoreactor chamber as a part of the atmospheric chemistry of methyl chavicol (ATMECH) project. Aerosol samples were collected using a particle into liquid sampler (PILS) and analysed offline using an extensive range of instruments including; high-performance liquid chromatography mass spectrometry (HPLC-ITMS), high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-QTOFMS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The SOA yield was determined as 18 and 29% for an initial VOC mixing ratio of 212 and 460 ppbv (parts per billion by volume) respectively; using a VOC:NOx ratio of ~5:1. In total, 59 SOA compounds were observed and the structures of 10 compounds have been identified using high-resolution tandem mass spectrometry. The addition of hydroxyl and/or nitro-functional groups to the aromatic ring appears to be an important mechanistic pathway for aerosol formation. This results in the formation of compounds with both low volatility and high O:C ratios, where functionalisation rather than fragmentation is mainly observed as a result of the stability of the ring. The SOA species observed can be characterised as semi-volatile to low-volatility oxygenated organic aerosol (SVOOA and LVOOA) components and therefore may be important in aerosol formation and growth.

  13. Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system.

    PubMed

    Ohtomo, Yoko; Ijiri, Akira; Ikegawa, Yojiro; Tsutsumi, Masazumi; Imachi, Hiroyuki; Uramoto, Go-Ichiro; Hoshino, Tatsuhiko; Morono, Yuki; Sakai, Sanae; Saito, Yumi; Tanikawa, Wataru; Hirose, Takehiro; Inagaki, Fumio

    2013-01-01

    Geological CO2 sequestration in unmineable subsurface oil/gas fields and coal formations has been proposed as a means of reducing anthropogenic greenhouse gasses in the atmosphere. However, the feasibility of injecting CO2 into subsurface depends upon a variety of geological and economic conditions, and the ecological consequences are largely unpredictable. In this study, we developed a new flow-through-type reactor system to examine potential geophysical, geochemical and microbiological impacts associated with CO2 injection by simulating in-situ pressure (0-100 MPa) and temperature (0-70°C) conditions. Using the reactor system, anaerobic artificial fluid and CO2 (flow rate: 0.002 and 0.00001 ml/min, respectively) were continuously supplemented into a column comprised of bituminous coal and sand under a pore pressure of 40 MPa (confined pressure: 41 MPa) at 40°C for 56 days. 16S rRNA gene analysis of the bacterial components showed distinct spatial separation of the predominant taxa in the coal and sand over the course of the experiment. Cultivation experiments using sub-sampled fluids revealed that some microbes survived, or were metabolically active, under CO2-rich conditions. However, no methanogens were activated during the experiment, even though hydrogenotrophic and methylotrophic methanogens were obtained from conventional batch-type cultivation at 20°C. During the reactor experiment, the acetate and methanol concentration in the fluids increased while the δ(13)Cacetate, H2 and CO2 concentrations decreased, indicating the occurrence of homo-acetogenesis. 16S rRNA genes of homo-acetogenic spore-forming bacteria related to the genus Sporomusa were consistently detected from the sandstone after the reactor experiment. Our results suggest that the injection of CO2 into a natural coal-sand formation preferentially stimulates homo-acetogenesis rather than methanogenesis, and that this process is accompanied by biogenic CO2 conversion to acetate. PMID:24348470

  14. Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system

    PubMed Central

    Ohtomo, Yoko; Ijiri, Akira; Ikegawa, Yojiro; Tsutsumi, Masazumi; Imachi, Hiroyuki; Uramoto, Go-Ichiro; Hoshino, Tatsuhiko; Morono, Yuki; Sakai, Sanae; Saito, Yumi; Tanikawa, Wataru; Hirose, Takehiro; Inagaki, Fumio

    2013-01-01

    Geological CO2 sequestration in unmineable subsurface oil/gas fields and coal formations has been proposed as a means of reducing anthropogenic greenhouse gasses in the atmosphere. However, the feasibility of injecting CO2 into subsurface depends upon a variety of geological and economic conditions, and the ecological consequences are largely unpredictable. In this study, we developed a new flow-through-type reactor system to examine potential geophysical, geochemical and microbiological impacts associated with CO2 injection by simulating in-situ pressure (0–100 MPa) and temperature (0–70°C) conditions. Using the reactor system, anaerobic artificial fluid and CO2 (flow rate: 0.002 and 0.00001 ml/min, respectively) were continuously supplemented into a column comprised of bituminous coal and sand under a pore pressure of 40 MPa (confined pressure: 41 MPa) at 40°C for 56 days. 16S rRNA gene analysis of the bacterial components showed distinct spatial separation of the predominant taxa in the coal and sand over the course of the experiment. Cultivation experiments using sub-sampled fluids revealed that some microbes survived, or were metabolically active, under CO2-rich conditions. However, no methanogens were activated during the experiment, even though hydrogenotrophic and methylotrophic methanogens were obtained from conventional batch-type cultivation at 20°C. During the reactor experiment, the acetate and methanol concentration in the fluids increased while the δ13Cacetate, H2 and CO2 concentrations decreased, indicating the occurrence of homo-acetogenesis. 16S rRNA genes of homo-acetogenic spore-forming bacteria related to the genus Sporomusa were consistently detected from the sandstone after the reactor experiment. Our results suggest that the injection of CO2 into a natural coal-sand formation preferentially stimulates homo-acetogenesis rather than methanogenesis, and that this process is accompanied by biogenic CO2 conversion to acetate. PMID

  15. Ab initio reaction kinetics of hydrogen abstraction from methyl formate by hydrogen, methyl, oxygen, hydroxyl, and hydroperoxy radicals.

    PubMed

    Tan, Ting; Pavone, Michele; Krisiloff, David B; Carter, Emily A

    2012-08-23

    Combustion of renewable biofuels, including energy-dense biodiesel, is expected to contribute significantly toward meeting future energy demands in the transportation sector. Elucidating detailed reaction mechanisms will be crucial to understanding biodiesel combustion, and hydrogen abstraction reactions are expected to dominate biodiesel combustion during ignition. In this work, we investigate hydrogen abstraction by the radicals H·, CH(3)·, O·, HO(2)·, and OH· from methyl formate, the simplest surrogate for complex biodiesels. We evaluate the H abstraction barrier heights and reaction enthalpies, using multireference correlated wave function methods including size-extensivity corrections and extrapolation to the complete basis set limit. The barrier heights predicted for abstraction by H·, CH(3)·, and O· are in excellent agreement with derived experimental values, with errors ≤1 kcal/mol. We also predict the reaction energetics for forming reactant complexes, transition states, and product complexes for reactions involving HO(2)· and OH·. High-pressure-limit rate constants are computed using transition state theory within the separable-hindered-rotor approximation for torsions and the harmonic oscillator approximation for other vibrational modes. The predicted rate constants differ significantly from those appearing in the latest combustion kinetics models of these reactions. PMID:22830521

  16. Fumigation of wheat using liquid ethyl formate plus methyl isothiocyanate in 50-tonne farm bins.

    PubMed

    Ren, Yonglin; Lee, Byungho; Mahon, Daphne; Xin, Ni; Head, Matthew; Reid, Robin

    2008-04-01

    Australian Standard White wheat, Triticum aestivum L. (a marketing grade with mixed grain hardness),with a moisture content of 12.5% was fumigated with a new ethyl formate formulation (95% ethyl formate plus 5% methyl isothiocyanate) identified and developed by Commonwealth Scientific and Industrial Research Organization Entomology, Canberra, Australia. Wheat was fumigated with the formulation at a calculated application rate of 80 g/m3 in two 50-tonne sealed metal vertical silos located at Fisherman Islands, Queensland, Australia. Access was gained through the top of the silo where the application of the formulation was completed within a few minutes by pouring it onto the top of the wheat. After 2 h of recirculation, using a 0.5-kW fan, the in-bin concentrations of ethyl formate achieved equilibrium with a concentration variation < 7%. The ethyl formate concentration, in both silos 1 and 2, during the first day's exposure period remained above 10 g/m3. The concentration of ethyl formate by time product achieved was 790 and 650 g h/m3 in silos 1 and 2, respectively. In silo 1, the formulation was sufficient to kill all life stages of mixed age cultures of Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Tribolium castaneum (Herbst). In silo 2, control was 100% for R. dominica and T. castaneum and 99.4% for S. oryzae. After 5 d fumigation, the silo top-hatch was opened but no forced aeration was initiated. The in-bin concentration of ethyl formate was lower than the Australian experimental threshold limit value of 100 ppm. The ethyl formate and methyl isothiocyanate residues in the grain had declined to below the Australian experimental maximum residue limit of 0.2 and 0.1 mg/kg, respectively. The workspace and environmental levels of ethyl formate and methyl isothiocyanate were less than the detection limit of 0.1 ppm. The treatment with ethyl formate formulation had no affect on the wheat germination and seed color compared with untreated controls. PMID

  17. Using physiologically based pharmacokinetic modeling to address nonlinear kinetics and changes in rodent physiology and metabolism due to aging and adaptation in deriving reference values for propylene glycol methyl ether and propylene glycol methyl ether acetate.

    SciTech Connect

    Kirman, C R.; Sweeney, Lisa M.; Corley, Rick A.; Gargas, M L.

    2005-04-01

    Reference values, including an oral reference dose (RfD) and an inhalation reference concentration (RfC), were derived for propylene glycol methyl ether (PGME), and an oral RfD was derived for its acetate (PGMEA). These values were based upon transient sedation observed in F344 rats and B6C3F1 mice during a two-year inhalation study. The dose-response relationship for sedation was characterized using internal dose measures as predicted by a physiologically based pharmacokinetic (PBPK) model for PGME and its acetate. PBPK modeling was used to account for changes in rodent physiology and metabolism due to aging and adaptation, based on data collected during weeks 1, 2, 26, 52, and 78 of a chronic inhalation study. The peak concentration of PGME in richly perfused tissues was selected as the most appropriate internal dose measure based upon a consideration of the mode of action for sedation and similarities in tissue partitioning between brain and other richly perfused tissues. Internal doses (peak tissue concentrations of PGME) were designated as either no-observed-adverse-effect levels (NOAELs) or lowest-observed-adverse-effect levels (LOAELs) based upon the presence or absence of sedation at each time-point, species, and sex in the two year study. Distributions of the NOAEL and LOAEL values expressed in terms of internal dose were characterized using an arithmetic mean and standard deviation, with the mean internal NOAEL serving as the basis for the reference values, which was then divided by appropriate uncertainty factors. Where data were permitting, chemical-specific adjustment factors were derived to replace default uncertainty factor values of ten. Nonlinear kinetics are were predicted by the model in all species at PGME concentrations exceeding 100 ppm, which complicates interspecies and low-dose extrapolations. To address this complication, reference values were derived using two approaches which differ with respect to the order in which these extrapolations

  18. Amide-conjugated indole-3-acetic acid and adventitious root formation in mung bean cuttings

    SciTech Connect

    Norcini, J.G.

    1986-01-01

    The purpose of this research was to investigate further the relationship between amide-conjugated auxin and adventitious root formation. Indoleacetylaspartic acid (IAA-aspartate) was positively identified as the predominant conjugate isolated from mung bean cuttings after the cuttings has been treated with 10/sup -3/ M IAA. In cuttings treated with (1-/sup 14/C)IAA immediately after excision (0 hr), the percent of extractable /sup 14/C in IAA-aspartate in the hypocotyl sharply increased until 36 hr, then steadily declined. (/sup 14/C)IAA was completely metabolized between 12 and 24 hr. The rooting activities of IAA-L-aspartate, IAA-L-alanine, and IAA-glycine were determined at various stages of root formation; some cuttings were pretreated with 10/sup -3/ M IAA at 0 hr. Pretreated cuttings that were treated with IAA-glycine at 12, 24, 36 hr exhibited the greatest consistency between replications, the greatest number of long roots, and the longest roots. The conjugates did not stimulate rooting as effectively as IAA, yet like IAA, generally enhanced rooting the greatest when applied before the first cell division (24 hr).

  19. Determination of enthalpy of formation of methyl and ethyl esters of fatty acids.

    PubMed

    Lapuerta, Magín; Rodríguez-Fernández, José; Oliva, Fermín

    2010-02-01

    Biofuels composed by fatty acid methyl esters are widely used as partly substituting fuels for diesel fossil fuels. Additionally, it is expected that the diesel biofuel norms will be extended to ethyl esters produced from bioethanol in the upcoming years. A precise knowledge of the standard enthalpy of formation is necessary for the calculation of some parameters useful for the analysis of the combustion process and emissions of a diesel engine operating with different fuels, such as the heating value, the adiabatic flame temperature or the kinetic mechanisms. However, experimental data for this property are scarce, and only available for short-chain, saturated methyl esters. In this work, four estimation methods for the calculation of the enthalpy of formation are examined and compared. Three of them are simple methods based on groups or bonds contribution, and another one is a computational method (with Gaussian 03 software). After presenting the implementation rules for each of them, conclusions are stated based on the results attained. Gaussian and Benson-Groups methods seem to be more accurate in predicting the actual values of the enthalpy of formation, both methods considering the separation between double bonds and the edge effects in the molecule. However, only the Gaussian method considers the effect of the position of the double bond in the molecule for all the unsaturated esters. PMID:19917272

  20. The Complete, Temperature Resolved Spectrum of Methyl Formate Between 214 and 265 GHZ

    NASA Astrophysics Data System (ADS)

    McMillan, James P.; Fortman, Sarah; Neese, Christopher F.; De Lucia, Frank C.

    2015-06-01

    We have studied methyl formate, one of the so-called 'astronomical weeds', in the 214--265 GHz band. We have experimentally gathered a set of intensity calibrated, complete, and temperature resolved spectra from across the astronomically significant temperature range of 248--406 K. Using our previously reported method of analysis, the point by point method, we are capable of generating the complete spectrum at an arbitrary temperature. Thousands of lines, of nontrivial intensity, which were previously not included in the available astrophysical catalogs have been found. The sensitivity of the point by point analysis is such that we are able to identify lines which would not have manifest in a single scan across the band. The consequence has been to reveal not only a number of new methyl formate lines, but also trace amounts of contaminants. We show how the intensities from the contaminants can be removed with indiscernible impact on the signal from methyl formate. To do this we use the point by point results from our previous studies of these contaminants. The efficacy of this process serves as strong proof of concept for usage of our point by point results on the problem of the 'weeds'. The success of this approach for dealing with the weeds has also previously been reported. J.~McMillan, S.~Fortman, C.~Neese, F.~DeLucia, ApJ. 795, 56 (2014) S.~Fortman, J.~McMillan, C.~Neese, S.~Randall, and A.~Remijan, J.~Mol.~Spectrosc. 280, 11 (2012).

  1. Contribution of artifacts to N-methylated piperazine cyanide adduct formation in vitro from N-alkyl piperazine analogs.

    PubMed

    Zhang, Minli; Resuello, Christina M; Guo, Jian; Powell, Mark E; Elmore, Charles S; Hu, Jun; Vishwanathan, Karthick

    2013-05-01

    In the liver microsome cyanide (CN)-trapping assays, piperazine-containing compounds formed significant N-methyl piperazine CN adducts. Two pathways for the N-methyl piperazine CN adduct formation were proposed: 1) The α-carbon in the N-methyl piperazine is oxidized to form a reactive iminium ion that can react with cyanide ion; 2) N-dealkylation occurs followed by condensation with formaldehyde and dehydration to produce N-methylenepiperazine iminium ion, which then reacts with cyanide ion to form the N-methyl CN adduct. The CN adduct from the second pathway was believed to be an artifact or metabonate. In the present study, a group of 4'-N-alkyl piperazines and 4'-N-[¹³C]methyl-labeled piperazines were used to determine which pathway was predominant. Following microsomal incubations in the presence of cyanide ions, a significant percentage of 4'-N-[¹³C]methyl group in the CN adduct was replaced by an unlabeled natural methyl group, suggesting that the second pathway was predominant. For 4'-N-alkyl piperazine, the level of 4'-N-methyl piperazine CN adduct formation was limited by the extent of prior 4'-N-dealkylation. In a separate study, when 4'-NH-piperaziens were incubated with potassium cyanide and [¹³C]-labeled formaldehyde, 4'-N-[¹³C]methyl piperazine CN-adduct was formed without NADPH or liver microsome suggesting a direct Mannich reaction is involved. However, when [¹³C]-labeled methanol or potassium carbonate was used as the one-carbon donor, 4'-N-[¹³C]methyl piperazine CN adduct was not detected without liver microsome or NADPH present. The biologic and toxicological implications of bioactivation via the second pathway necessitate further investigation because these one-carbon donors for the formation of reactive iminium ions could be endogenous and readily available in vivo. PMID:23431111

  2. Influence of C5-methylation of cytosine on the formation of cyclobutane pyrimidine dimers

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyi; Eriksson, Leif A.

    2005-01-01

    The reaction pathways for thermal and photochemical formation of 5-methylcytosine (m 5C) pyrimidine dimers (CPD) are explored using density functional theory techniques. It is shown that the methylation of cytosine does not contribute to an increased yield of CPDs after UV irradiation due to an even lower excitation energy at the reactant complex of m 5C as compared to cytosine, a larger barrier to reach the decay channel corresponding to the transition state structure along the ground state reaction path, and a higher-lying decay channel.

  3. THz spectroscopy and first ISM detection of excited torsional states of 13C-methyl formate

    NASA Astrophysics Data System (ADS)

    Haykal, I.; Carvajal, M.; Tercero, B.; Kleiner, I.; López, A.; Cernicharo, J.; Motiyenko, R. A.; Huet, T. R.; Guillemin, J. C.; Margulès, L.

    2014-08-01

    Context. An astronomical survey of interstellar molecular clouds needs a previous analysis of the spectra in the microwave and sub-mm energy range of organic molecules to be able to identify them. We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of rotational spectra. These constants can be used to predict the transitions frequencies very precisely that were not measured in the laboratory. Aims: We present the experimental study and its theoretical analysis for two 13C-methyl formate isotopologues to detect these two isotopologues for the first time in their excited torsional states, which lie at 130 cm-1 (200 K) in Orion-KL. Methods: New spectra of HCOO13CH3 (13C2) methyl formate were recorded with the mm- and submm-wave spectrometer in Lille from 50 to 940 GHz. A global fit for vt = 0 and 1 was accomplished with the BELGI program to reproduce the experimental spectra with greater accuracy. Results: We analysed 5728 and 2881 new lines for vt = 0 and 1 for HCOO13CH3. These new lines were globally fitted with 846 previously published lines for vt = 0. In consequence, 52 parameters of the RAM Hamiltonian were accurately determined and the value of the barrier height (V3 = 369.93168(395) cm-1) was improved. We report the detection of the first excited torsional states (vt = 1) in Orion-KL for the 13C2 and 13C1 methyl formate based on the present analysis and previously published data. We provide column densities, isotopic abundances, and vibrational temperatures for these species. Conclusions: Following this work, accurate prediction can be provided. This permits detecting 135 features of the first excited torsional states of 13C-methyl formate isotopologues in Orion-KL in the 80-280 GHz frequency range, without missing lines. Full Table A.1 and the IRAM spectra as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568

  4. The Acid Catalyzed Nitration of Methanol: Formation of Methyl Nitrate via Aerosol Chemistry

    NASA Technical Reports Server (NTRS)

    Riffel, Brent G.; Michelsen, Rebecca R.; Iraci, Laura T.

    2004-01-01

    The liquid phase acid catalyzed reaction of methanol with nitric acid to yield methyl nitrate under atmospheric conditions has been investigated using gas phase infrared spectroscopy. This nitration reaction is expected to occur in acidic aerosol particles found in the upper troposphere/lower stratosphere as highly soluble methanol and nitric acid diffuse into these aerosols. Gaseous methyl nitrate is released upon formation, suggesting that some fraction of NO(x) may he liberated from nitric acid (methyl nitrate is later photolyzed to NO(x)) before it is removed from the atmosphere by wet deposition. Thus, this reaction may have important implications for the NO(x) budget. Reactions have been initiated in 45-62 wt% H2SO4 solutions at 10.0 C. Methyl nitrate production rates increased exponentially with acidity within the acidity regime studied. Preliminary calculations suggest that the nitronium ion (NO2(+) is the active nitrating agent under these conditions. The reaction order in methanol appears to depend on the water/methanol ratio and varies from first to zeroth order under conditions investigated. The nitration is first order in nitronium at all acidities investigated. A second order rate constant, kappa(sub 2), has been calculated to be 1 x 10(exp 8)/ M s when the reaction is first order in methanol. Calculations suggest the nitration is first order in methanol under tropospheric conditions. The infinitesimal percentage of nitric acid in the nitronium ion form in this acidity regime probably makes this reaction insignificant for the upper troposphere; however, this nitration may become significant in the mid stratosphere where colder temperatures increase nitric acid solubility and higher sulfuric acid content shifts nitric acid speciation toward the nitronium ion.

  5. Equilibrium structure in the presence of internal rotation: A case study of cis-methyl formate

    NASA Astrophysics Data System (ADS)

    Demaison, J.; Margulès, L.; Kleiner, I.; Császár, A. G.

    2010-02-01

    The Born-Oppenheimer (BO) equilibrium molecular structure ( reBO) of cis-methyl formate has been determined at the CCSD(T) level of electronic structure theory using Gaussian basis sets of at least quadruple-ζ quality and a core correlation correction. The quadratic, cubic and semi-diagonal quartic force field in normal coordinates has also been computed at the MP2 level employing a basis set of triple-ζ quality. A semi-experimental equilibrium structure ( reSE) has been derived from experimental ground-state rotational constants and the lowest-order rovibrational interaction parameters calculated from the ab initio cubic force field. To determine reSE structures, it is important to start from accurate ground-state rotational constants. Different spectroscopic methods, applicable in the presence of internal rotation and used in the literature to obtain "unperturbed" rotational constants from the analysis and fitting of the spectrum, are reviewed and compared. They are shown to be compatible though their precision may be different. The reBO and reSE structures are in good agreement showing that, in the particular case of cis-methyl formate, the methyl torsion can still be treated as a small-amplitude vibration. The best equilibrium structure obtained for cis-methyl formate is: r(C m-O) = 1.434 Å, r(O-C c) = 1.335 Å, r(C m-H s) = 1.083 Å, r(C m-H a) = 1.087 Å, r(C c-H) = 1.093 Å, r(C dbnd O) = 1.201 Å, ∠(COC) = 114.4°, ∠(CCH s) = 105.6°, ∠(CCH a) = 110.2°, ∠(OCH) = 109.6°, ∠(OCO) = 125.5°, and τ(H aCOC) = 60.3°. The accuracy is believed to be about 0.001 Å for the bond lengths and 0.1° for the angles.

  6. A rare case of pseudotumor formation associated with methyl methacrylate hypersensitivity in a patient following cemented total knee arthroplasty.

    PubMed

    Kenan, Shachar; Kahn, Leonard; Haramati, Noga; Kenan, Samuel

    2016-08-01

    Hypersensitivity to orthopedic implant materials has been well documented with potential catastrophic consequences if not addressed pre-operatively. The spectrum of reactions is wide, from mild non-specific pain with localized erythema to severe periprosthetic inflammatory destruction and pseudotumor formation. It is therefore essential to identify patients who have or are at risk for implant-associated hypersensitivity. Although metal sensitivity is commonly cited as the cause of these reactions, methyl methacrylate (MMA) has rarely been implicated. To the best of our knowledge, methyl methacrylate-associated pseudotumor formation has not yet been described. The following is a case report of a 68-year-old female who, after undergoing a routine cemented right total knee arthroplasty, developed a painless, enlarging mass during a 13-year period. This mass was found to be a pseudotumor in association with methyl methacrylate hypersensitivity. A review of pseudotumor pathogenesis, methyl methacrylate hypersensitivity, and preoperative preventative care is discussed. PMID:27022733

  7. Using physiologically-based pharmacokinetic modeling to address nonlinear kinetics and changes in rodent physiology and metabolism due to aging and adaptation in deriving reference values for propylene glycol methyl ether and propylene glycol methyl ether acetate.

    PubMed

    Kirman, C R; Sweeney, L M; Corley, R; Gargas, M L

    2005-04-01

    Reference values, including an oral reference dose (RfD) and an inhalation reference concentration (RfC), were derived for propylene glycol methyl ether (PGME), and an oral RfD was derived for its acetate (PGMEA). These values were based on transient sedation observed in F344 rats and B6C3F1 mice during a two-year inhalation study. The dose-response relationship for sedation was characterized using internal dose measures as predicted by a physiologically-based pharmacokinetic (PBPK) model for PGME and its acetate. PBPK modeling was used to account for changes in rodent physiology and metabolism due to aging and adaptation, based on data collected during Weeks 1, 2, 26, 52, and 78 of a chronic inhalation study. The peak concentration of PGME in richly perfused tissues (i.e., brain) was selected as the most appropriate internal dose measure based on a consideration of the mode of action for sedation and similarities in tissue partitioning between brain and other richly perfused tissues. Internal doses (peak tissue concentrations of PGME) were designated as either no-observed-adverse-effect levels (NOAELs) or lowest-observed-adverse-effect levels (LOAELs) based on the presence or the absence of sedation at each time point, species, and sex in the two-year study. Distributions of the NOAEL and LOAEL values expressed in terms of internal dose were characterized using an arithmetic mean and standard deviation, with the mean internal NOAEL serving as the basis for the reference values, which was then divided by appropriate uncertainty factors. Where data were permitting, chemical-specific adjustment factors were derived to replace default uncertainty factor values of 10. Nonlinear kinetics, which was predicted by the model in all species at PGME concentrations exceeding 100 ppm, complicate interspecies, and low-dose extrapolations. To address this complication, reference values were derived using two approaches that differ with respect to the order in which these

  8. The Microwave Spectrum of the HCOOCD_2H Species of Methyl Formate

    NASA Astrophysics Data System (ADS)

    Coudert, L. H.; Huet, T. R.; Margulès, L.; Motiyenko, R.; Mollendal, H.

    2010-06-01

    Methyl formate is a non-rigid molecule displaying internal rotation of its methyl group. The microwave spectra of its normal and mono deuterated HCOOCH_2D species have already been studied and values for the tunneling splitting due to the internal rotation were determined. The normal species displays a 405 MHz A/E splitting, the mono deuterated one, a smaller 84.76 MHz A'/A'' splitting. For the bideuterated species HCOOCD_2H, the value of this splitting is not known as its microwave spectrum has not been studied yet. In this paper experimental and theoretical investigations of the microwave spectrum of HCOOCD_2H are presented. More than 9000 transitions were measured with a submillimeter wave spectrometer. About 20 lines were recorded with a molecular beam spectrometer. Like for the mono deuterated species,^c depending on the location of the only hydrogen atom of the methyl group, two configurations arise. The C_s-symmetry H-in plane configuration displays a rigid rotator spectrum and its data was analyzed using a Watson-type Hamiltonian. The C_1-symmetry H-out of plane configuration undergoes the large amplitude internal rotation. Its data was analyzed using the so called water dimer formalism which allowed us to accurately reproduce the observed frequencies and to obtain the value of the tunneling splitting as well as the parameters involved in its rotational dependence. The hyperfine structure due to quadrupole coupling at the two deuterium atoms was also analyzed. Unexpectedly, for the H-out of plane configuration, the observed hyperfine patterns are neither those expected for two equivalent deuterium atoms nor those of a rigid molecule. Ilyushin, Kryvda, and Alekseev, J. Mol. Spec. 255 (2009) 32. Margulès, Coudert, Mollendal, Guillemin, Huet, and Janeckovà, J. Mol. Spec. 254 (2009) 55. Hougen, J. Mol. Spec. 114 (1985) 395; and Coudert and Hougen, J. Mol. Spec. 130 (1988) 86.

  9. MICROWAVE-ASSISTED PREPARATION OF 1-BUTYL-3-METHYLIMIDAZOLIUM TETRACHLOROGALLATE AND ITS CATALYTIC USE IN ACETAL FORMATION UNDER MILD CONDITIONS

    EPA Science Inventory

    1-Butyl-3-methylimidazolium tetrachlorogallate, [bmim][GaCl4], prepared via microwave-assisted protocol, is found to be an active catalyst for the efficient acetalization of aldehydes under mild conditions.

  10. Synchrotron FTIR spectroscopy of weak torsional bands: A case study of cis-methyl formate

    NASA Astrophysics Data System (ADS)

    Tudorie, M.; Ilyushin, V.; Vander Auwera, J.; Pirali, O.; Roy, P.; Huet, T. R.

    2012-08-01

    The far infrared spectrum of cis-methyl formate has been recorded on the AILES beamline of the synchrotron SOLEIL using a Fourier transform infrared spectrometer coupled to a long path cell. The very weak fundamental band associated with the methyl-top torsion mode (ν18) was observed. The frequency analysis was performed using the "rho axis method", and the microwave and millimeter-wave data from the literature. A precise determination of the band origins ({ν }_{18}^A = 132.4303 cm-1 and {ν }_{18}^E = 131.8445 cm-1) and of the barrier height [V3 = 370.7398 (58) cm-1] have been obtained. The intensity of the ν18 fundamental band was determined to be 3.4 × 10-21 cm-1/(molecule cm-2) at 297 K, equally shared among A-A and E-E transitions, thus leading to a dipole moment component μc(3) equal to 0.0483 D. The results were compared with the ab initio calcula-tions of Senent et al. [Astrophys. J. 627, 567 (2005)], 10.1086/430201.

  11. Light and acid dual-responsive organogel formation based on m-methyl red derivative.

    PubMed

    Cao, Xinhua; Gao, Aiping; Lv, Haiting; Wu, Yan; Wang, Xiuxiu; Fan, Yang

    2013-12-01

    A new gelator 1 that included m-methyl red was synthesized and fully characterized. It was found that the organogel of 1 was stable in DMSO even if the organogel was stimulated by acid or light. The organogel was thoroughly characterized using various microscopic techniques including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-vis and Fourier transform infrared (FTIR) spectra. The organogel exhibited tunable structures and optical properties under different stimulation. The regular nanoring structure was turned into microspheres after the organogel in DMSO was stimulated at 254 nm light or acid. At the same time, the color of molecule 1 in gel state and solution state was all changed after stimulation by light or acid. The hydrogen bonding and π-π stacking were found to be the main driving forces for gel formation. This dual-responsive gel held promise for soft materials application in upscale smart responsive materials. PMID:24135789

  12. An ALMA Imaging Study of Methyl Formate (HCOOCH3) in Torsionally Excited States toward Orion KL

    NASA Astrophysics Data System (ADS)

    Sakai, Yusuke; Kobayashi, Kaori; Hirota, Tomoya

    2015-04-01

    We recently reported the first identification of rotational transitions of methyl formate (HCOOCH3) in the second torsionally excited state toward Orion Kleinmann-Low (KL), observed with the Nobeyama 45 m telescope. In combination with the identified transitions of methyl formate in the ground state and the first torsional excited state, it was found that there is a difference in rotational temperature and vibrational temperature, where the latter is higher. In this study, high spatial resolution analysis by using Atacama Large Millimeter/Submillimeter Array (ALMA) science verification data was carried out to verify and understand this difference. Toward the Compact Ridge, two different velocity components at 7.3 and 9.1 km s-1 were confirmed, while a single component at 7.3 km s-1 was identified toward the Hot Core. The intensity maps in the ground, first, and second torsional excited states have quite similar distributions. Using extensive ALMA data, we determined the rotational and vibrational temperatures for the Compact Ridge and Hot Core by the conventional rotation diagram method. The rotational temperature and vibrational temperatures agree for the Hot Core and for one component of the Compact Ridge. At the 7.3 km s-1 velocity component for the Compact Ridge, the rotational temperature was found to be higher than the vibrational temperature. This is different from what we obtained from the results by using the single-dish observation. The difference might be explained by the beam dilution effect of the single-dish data and/or the smaller number of observed transitions within the limited range of energy levels (≤30 K) of Eu in the previous study.

  13. Carbon-isotopic analysis of dissolved acetate

    NASA Technical Reports Server (NTRS)

    Gelwicks, J. T.; Hayes, J. M.

    1990-01-01

    Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.

  14. Formation of embryogenic cell clumps from carrot epidermal cells is suppressed by 5-azacytidine, a DNA methylation inhibitor.

    PubMed

    Yamamoto, Nozomi; Kobayashi, Hatsumi; Togashi, Takashi; Mori, Yukiko; Kikuchi, Koji; Kuriyama, Kyoko; Tokuji, Yoshihiko

    2005-01-01

    Using a direct somatic embryogenesis system in carrot, we examined the role of DNA methylation in the change of cellular differentiation state, from somatic to embryogenic. 5-Azacytidine (aza-C), an inhibitor of DNA methylation suppressed the formation of embryogenic cell clumps from epidermal carrot cells. Aza-C also downregulated the expression of DcLEC1c, a LEC1-like embryonic gene in carrot, during morphogenesis of embryos. A carrot DNA methyltransferase gene, Met1-5 was expressed transiently after the induction of somatic embryogenesis by 2,4-dichlorophenoxyacetic acid (2,4-D), before the formation of embryogenic cell clumps. These findings suggested the significance of DNA methylation in acquiring the embryogenic competence in somatic cells in carrot. PMID:15700420

  15. Effect of Ionization on Infrared and Electronic Absorption Spectra of Methyl and Ethyl Formate in the Gas Phase and in Astrophysical H2O Ice: A Computational Study

    NASA Astrophysics Data System (ADS)

    Naganathappa, Mahadevappa; Chaudhari, Ajay

    2011-04-01

    This work reports infrared and electronic absorption spectra of trans and gauche conformers of neutral ethyl formate, trans and cis conformers of neutral methyl formate, their ions in the gas phase, and neutral ethyl and methyl formate in astrophysical H2O ice. The second-order Møller-Plesset perturbation (MP2) method with TZVP basis set has been used to obtain ground-state geometries. An influence of ice on vibrational frequencies of neutral ethyl and methyl formate was obtained using integral equation formalism polarizable continnum model (IEFPCM). Significant shift in vibrational frequencies for neutral methyl and ethyl formate when studied in H2O ice and upon ionization is observed. Rotational and distortion constants for neutral ethyl and methyl formate from this work are in excellent agreement with the available experimental values. Electronic absorption spectra of conformers of ethyl and methyl formate and their ions are obtained using time-dependent density functional method (TDDFT). The nature of electronic transitions is also identified. We suggested lines especially good to detect these molecules in interstellar medium. Using these lines, we can identify the conformers of ethyl and methyl formate in gas phase and H2O ice in interstellar medium. This comparative study should provide useful guidelines to detect conformers of ethyl and methyl formate and their ions in gas phase and neutral molecules in H2O ice in different astronomical environment.

  16. The Complete, Temperature Resolved Experimental Spectrum of Methyl Formate (HCOOCH3) between 214.6 and 265.4 GHz

    NASA Astrophysics Data System (ADS)

    McMillan, James P.; Fortman, Sarah M.; Neese, Christopher F.; De Lucia, Frank C.

    2016-05-01

    Because methyl formate (HCOOCH3) is abundant in the interstellar medium and has a strong, complex spectrum, it is a major contributor to the list of identified astrophysical lines. Because of its spectral complexity, with many low lying torsional and vibrational states, the quantum mechanical (QM) analysis of its laboratory spectrum is challenging and thus incomplete. As a result it is assumed that methyl formate is also one of the major contributors to the lists of unassigned lines in astrophysical spectra. This paper provides a characterization, without the need for QM analysis, of the spectrum of methyl formate between 214.6 and 265.4 GHz for astrophysically significant temperatures. The experimental basis for this characterization is a set of 425 spectra, with absolute intensity calibration, recorded between 248 and 408 K. Analysis of these spectra makes possible the calculation of the Complete Experimental Spectrum of methyl formate as a function of temperature. Of the 7132 strongest lines reported in this paper, 2523 are in the QM catalogs. Intensity differences of 5%–10% from those calculated via QM models were also found. Results are provided in a frequency point-by-point catalog that is well suited for the simulation of overlapped spectra. The common astrophysical line frequency, line strength, and lower state energy catalog is also provided.

  17. NMDA Receptor- and ERK-Dependent Histone Methylation Changes in the Lateral Amygdala Bidirectionally Regulate Fear Memory Formation

    ERIC Educational Resources Information Center

    Gupta-Agarwal, Swati; Jarome, Timothy J.; Fernandez, Jordan; Lubin, Farah D.

    2014-01-01

    It is well established that fear memory formation requires de novo gene transcription in the amygdala. We provide evidence that epigenetic mechanisms in the form of histone lysine methylation in the lateral amygdala (LA) are regulated by NMDA receptor (NMDAR) signaling and involved in gene transcription changes necessary for fear memory…

  18. Methyl Protodioscin, a Steroidal Saponin, Inhibits Neointima Formation in Vitro and in Vivo.

    PubMed

    Chung, Yun-Lung; Pan, Chun-Hsu; Wang, Charles C-N; Hsu, Kai-Cheng; Sheu, Ming-Jyh; Chen, Hai-Feng; Wu, Chieh-Hsi

    2016-06-24

    Restenosis (or neointimal hyperplasia) remains a clinical limitation of percutaneous coronary angioplasty. Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are known to be involved in the development of restenosis. The present study aimed to investigate the ability and molecular mechanisms of methyl protodioscin (1), a steroidal saponin isolated from the root of Dioscorea nipponica, to inhibit neointimal formation. Our study demonstrated that 1 markedly inhibited the growth and migration of VSMCs (A7r5 cells). A cytometric analysis suggested that 1 induced growth inhibition by arresting VSMCs at the G1 phase of the cell cycle. A rat carotid artery balloon injury model indicated that neointima formation of the balloon-injured vessel was markedly reduced after extravascular administration of 1. Compound 1 decreased the expression levels of ADAM15 (a disintegrin and metalloprotease 15) and its downstream signaling pathways in the VSMCs. Moreover, the expressions and activities of matrix metalloproteinases (MMP-2 and MMP-9) were also suppressed by 1 in a concentration-dependent manner. Additionally, the molecular mechanisms appear to be mediated, in part, through the downregulation of ADAM15, FAK, ERK, and PI3K/Akt. PMID:27227546

  19. Effect of methylazoxymethanol acetate on bluegill sunfish cell cultures in vitro

    SciTech Connect

    Borenfreund, E.; Babich, H.; Martin-Alguacil, N.

    1989-06-01

    An epithelioid cell line derived from fin tissue of bluegill sunfish (designated BG/F) exhibited early indications of cell transformation upon exposure to methylazoxymethanol acetate (MAM acetate). Such changes included the induction of polyploidy, increased colony-forming efficiency, loss of contact inhibition, and formation of transformed foci. Unlike later transformation characteristics observed with mammalian cells, the MAM acetate-treated BG/F cells could not be propagated under conditions of anchorage independence in soft agar. Incubation of BG/F cells with N-methyl-N'-nitro-N-nitrosoguanidine, followed by exposure to 12-O-tetradecanoylphorbol-13-acetate, was not observed to cause cell transformation under the experimental conditions. The controls of a fibroblastic cell culture derived from gill tissue of bluegill sunfish showed spontaneous transformation after 6 months of passage, similar to the transformation observed in the experimental MAM acetate treated gill cultures.

  20. Rhodium-Catalyzed Ketone Methylation Using Methanol Under Mild Conditions: Formation of α-Branched Products**

    PubMed Central

    Chan, Louis K M; Poole, Darren L; Shen, Di; Healy, Mark P; Donohoe, Timothy J

    2014-01-01

    The rhodium-catalyzed methylation of ketones has been accomplished using methanol as the methylating agent and the hydrogen-borrowing method. The sequence is notable for the relatively low temperatures that are required and for the ability of the reaction system to form α-branched products with ease. Doubly alkylated ketones can be prepared from methyl ketones and two different alcohols by using a sequential one-pot iridium- and rhodium-catalyzed process. PMID:24288297

  1. Hydroxyl radical formation via iron-mediated Fenton chemistry is inhibited by methylated catechols.

    PubMed

    Nappi, A J; Vass, E

    1998-09-16

    The differing effects of O-methylated catecholamines and their dihydroxyphenyl precursors on the production of *OH were quantified using a previously established specific salicylate hydroxylation assay in conjunction with a sensitive electrochemical detection system. The production of *OH by the Fenton reaction was diminished significantly by O-methylated catecholamines (O-methyldopa, O-methyldopamine, O-methyltyrosine, and N-acetyl-O-methyldopamine), whereas radical production was augmented by dihydroxyphenyls (DOPA, dopamine, and N-acetyldopamine), including those with methylated side chains (N-methyldopamine and alpha-methyldopa). Monohydroxyphenyls such as octopamine, tyramine, tyrosine, and alpha-methyltyrosine had little or no effect on radical production. These data show that a methyl group positioned on the side chain of a catecholamine does not alter its pro-oxidant behavior, while a methyl group positioned on the aromatic ring renders the catecholamine sterically or kinetically unfavorable for coordination with transition metals, thus preventing the promotion of Fenton chemistry. These results highlight the importance of O-methylation in forming catechols that are less reactive than their dihydroxyphenyl precursors. Thus, factors regulating the methylation of brain catecholamines may play a crucial role in mediating neuronal integrity during aging and in the pathogenesis of certain neurodegenerative disorders. Competitive side-chain methylation reactions may sustain or perpetuate some dihydroxyphenyls, creating an oxidatively less favorable environment for cells than would result from compounds formed by O-methylation. PMID:9813302

  2. Transient Ru-methyl formate intermediates generated with bifunctional transfer hydrogenation catalysts

    PubMed Central

    Perry, Richard H.; Brownell, Kristen R.; Chingin, Konstantin; Cahill, Thomas J.; Waymouth, Robert M.; Zare, Richard N.

    2012-01-01

    Desorption electrospray ionization (DESI) coupled to high-resolution Orbitrap mass spectrometry (MS) was used to study the reactivity of a (β-amino alcohol)(arene)RuCl transfer hydrogenation catalytic precursor in methanol (CH3OH). By placing [(p-cymene)RuCl2]2 on a surface and spraying a solution of β-amino alcohol in methanol, two unique transient intermediates having lifetimes in the submillisecond to millisecond range were detected. These intermediates were identified as Ru (II) and Ru (IV) complexes incorporating methyl formate (HCOOCH3). The Ru (IV) intermediate is not observed when the DESI spray solution is sparged with Ar gas, indicating that O2 dissolved in the solvent is necessary for oxidizing Ru (II) to Ru (IV). These proposed intermediates are supported by high-resolution and high mass accuracy measurements and by comparing experimental to calculated isotope profiles. Additionally, analyzing the bulk reaction mixture using gas chromatography-MS and nuclear magnetic resonance spectroscopy confirms the formation of HCOOCH3. These results represent an example that species generated from the (β-amino alcohol)(arene)RuCl (II) catalytic precursor can selectively oxidize CH3OH to HCOOCH3. This observation leads us to propose a pathway that can compete with the hydrogen transfer catalytic cycle. Although bifunctional hydrogen transfer with Ru catalysts has been well-studied, the ability of DESI to intercept intermediates formed in the first few milliseconds of a chemical reaction allowed identification of previously unrecognized intermediates and reaction pathways in this catalytic system. PMID:22315417

  3. Formation of DNA Methylation Patterns: Nonmethylated GATC Sequences in gut and pap Operons

    PubMed Central

    van der Woude, Marjan; Hale, W. Bradley; Low, David A.

    1998-01-01

    Most of the adenine residues in GATC sequences in the Escherichia coli chromosome are methylated by the enzyme deoxyadenosine methyltransferase (Dam). However, at least 20 GATC sequences remain nonmethylated throughout the cell cycle. Here we examined how the DNA methylation patterns of GATC sequences within the regulatory regions of the pyelonephritis-associated pilus (pap) operon and the glucitol utilization (gut) operon were formed. The results obtained with an in vitro methylation protection assay showed that the addition of the leucine-responsive regulatory protein (Lrp) to pap DNA was sufficient to protect the two GATC sequences in the pap regulatory region, GATC-I and GATC-II, from methylation by Dam. This finding was consistent with previously published data showing that Lrp was essential for methylation protection of these DNA sites in vivo. Methylation protection also occurred at a GATC site (GATC-44.5) centered 44.5 bp upstream of the transcription start site of the gutABD operon. Two proteins, GutR and the catabolite gene activator protein (CAP), bound to DNA sites overlapping the GATC-44.5-containing region of the gutABD operon. GutR, an operon-specific repressor, was essential for methylation protection in vivo, and binding of GutR protected GATC-44.5 from methylation in vitro. In contrast, binding of CAP at a site overlapping GATC-44.5 did not protect this site from methylation. Mutational analyses indicated that gutABD gene regulation was not controlled by methylation of GATC-44.5, in contrast to regulation of Pap pilus expression, which is directly controlled by methylation of the pap GATC-I and GATC-II sites. PMID:9811649

  4. Self-Assembly and Formation of Chromonic Liquid Crystals from the Dyes Quinaldine Red Acetate and Pyronin Y.

    PubMed

    Magana, J R; Homs, M; Solans, C; Obiols-Rabasa, M; Salonen, L M; Rodríguez-Abreu, C

    2016-01-14

    The aqueous self-assembly behavior of the dyes Quinaldine red acetate and Pyronin Y in a wide range of concentrations is reported here for the first time. (1)H NMR spectroscopy, polarized-light optical microscopy, and small and wide X-ray scattering were used to get insight into molecular interactions, phase boundaries and aggregate structure. Quinaldine red acetate and Pyronin Y self-organize into unimolecular stacks driven by attractive aromatic interactions. At high concentrations, spatial correlation among the molecular stacks gives rise to nematic liquid crystals in both systems. Quinaldine red acetate additionally produces a rare chromonic O phase built of columnar aggregates with anisotropic cross-section ordered in a rectangular lattice. The O phase changes into a columnar lamellar structure as a result of a temperature-induced phase transition. Results open the possibility of finding chromonic liquid crystals in other commercially available dyes with a similar molecular structure. This would eventually expand the availability of these unique soft materials and thus introduce new applications for marketed dyes. PMID:26700729

  5. The importance of being thiomethylated: formation, fate, and effects of methylated thioarsenicals

    EPA Science Inventory

    AbstractAlthough inorganic arsenic has long been recognized as a potent toxicant and carcinogen in humans, recent evidence shows that at least some of its effects are mediated by methylated metabolites. Elucidating the conversion of inorganic arsenic to mono-, di-, and tri-methyl...

  6. Development and Validation of a Stability Indicating RP-HPLC Method for Hydrocortisone Acetate Active Ingredient, Propyl Parahydroxybenzoate and Methyl Parahydroxybenzoate Preservatives, Butylhydroxyanisole Antioxidant, and Their Degradation Products in a Rectal Gel Formulation.

    PubMed

    Ascaso, Magda; Pérez-Lozano, Pilar; García, Mireia; García-Montoya, Encarna; Miñarro, Montse; Ticó, Josep R; Fàbregas, Anna; Carrillo, Carolina; Sarrate, Rocío; Suñé-Negre, Josep M

    2015-01-01

    A stability indicating method was established through a stress study, wherein different methods of degradation (oxidation, hydrolysis, photolysis, and temperature) were studied simultaneously to determine the active ingredient hydrocortisone acetate, preservatives propyl parahydroxybenzoate, and methyl parahydroxybenzoate, antioxidant butylhydroxyanisole (BHA), and their degradation products in a semisolid dosage gel form. The proposed method was suitably validated using a Zorbax SB-Phenyl column and gradient elution. The mobile phase consisted of a mixture of methanol, acetonitrile, and water in different proportions according to a planned program at a flow rate of 1.5 mL/min. The diode array detector was set at 240 nm for the active substance and two preservatives, and 290 nm for BHA. The validation study was conducted according to International Conference on Harmonization guidelines for specificity, linearity, repeatability, precision, and accuracy. The method was used for QC of hydrocortisone acetate gel and for the stability studies with the aim of quantifying the active substance, preservatives, antioxidant, and degradation products. It has proved to be suitable as a fast and reliable method for QC. PMID:25857875

  7. Studies of the acidic components of the Colorado Green River formation oil shale-Mass spectrometric identification of the methyl esters of extractable acids.

    NASA Technical Reports Server (NTRS)

    Haug, P.; Schnoes, H. K.; Burlingame, A. L.

    1971-01-01

    Study of solvent extractable acidic constituents of oil shale from the Colorado Green River Formation. Identification of individual components is based on gas chromatographic and mass spectrometric data obtained for their respective methyl esters. Normal acids, isoprenoidal acids, alpha, omega-dicarboxylic acids, mono-alpha-methyl dicarboxylic acids and methyl ketoacids were identified. In addition, the presence of monocyclic, benzoic, phenylalkanoic and naphthyl-carboxylic acids, as well as cycloaromatic acids, is demonstrated by partial identification.

  8. Neurospora Importin α Is Required for Normal Heterochromatic Formation and DNA Methylation

    PubMed Central

    Klocko, Andrew D.; Rountree, Michael R.; Grisafi, Paula L.; Hays, Shan M.; Adhvaryu, Keyur K.; Selker, Eric U.

    2015-01-01

    Heterochromatin and associated gene silencing processes play roles in development, genome defense, and chromosome function. In many species, constitutive heterochromatin is decorated with histone H3 tri-methylated at lysine 9 (H3K9me3) and cytosine methylation. In Neurospora crassa, a five-protein complex, DCDC, catalyzes H3K9 methylation, which then directs DNA methylation. Here, we identify and characterize a gene important for DCDC function, dim-3 (defective in methylation-3), which encodes the nuclear import chaperone NUP-6 (Importin α). The critical mutation in dim-3 results in a substitution in an ARM repeat of NUP-6 and causes a substantial loss of H3K9me3 and DNA methylation. Surprisingly, nuclear transport of all known proteins involved in histone and DNA methylation, as well as a canonical transport substrate, appear normal in dim-3 strains. Interactions between DCDC members also appear normal, but the nup-6dim-3 allele causes the DCDC members DIM-5 and DIM-7 to mislocalize from heterochromatin and NUP-6dim-3 itself is mislocalized from the nuclear envelope, at least in conidia. GCN-5, a member of the SAGA histone acetyltransferase complex, also shows altered localization in dim-3, raising the possibility that NUP-6 is necessary to localize multiple chromatin complexes following nucleocytoplasmic transport. PMID:25793375

  9. Laboratory and Tentative Interstellar Detection of Trans-Methyl Formate Using the Publicly Available Green Bank Telescope Primos Survey

    NASA Astrophysics Data System (ADS)

    Neill, Justin L.; Muckle, Matt T.; Zaleski, Daniel P.; Steber, Amanda L.; Pate, Brooks H.; Lattanzi, Valerio; Spezzano, Silvia; McCarthy, Michael C.; Remijan, Anthony J.

    2012-08-01

    The rotational spectrum of the higher-energy trans-conformational isomer of methyl formate has been assigned for the first time using several pulsed-jet Fourier transform microwave spectrometers in the 6-60 GHz frequency range. This species has also been sought toward the Sagittarius B2(N) molecular cloud using the publicly available PRIMOS survey from the Green Bank Telescope. We detect seven absorption features in the survey that coincide with laboratory transitions of trans-methyl formate, from which we derive a column density of 3.1 (+2.6, -1.2) × 1013 cm-2 and a rotational temperature of 7.6 ± 1.5 K. This excitation temperature is significantly lower than that of the more stable cis conformer in the same source but is consistent with that of other complex molecular species recently detected in Sgr B2(N). The difference in the rotational temperatures of the two conformers suggests that they have different spatial distributions in this source. As the abundance of trans-methyl formate is far higher than would be expected if the cis and trans conformers are in thermodynamic equilibrium, processes that could preferentially form trans-methyl formate in this region are discussed. We also discuss measurements that could be performed to make this detection more certain. This manuscript demonstrates how publicly available broadband radio astronomical surveys of chemically rich molecular clouds can be used in conjunction with laboratory rotational spectroscopy to search for new molecules in the interstellar medium.

  10. Crystal structures of 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate and 4-methyl-2-oxo-2H-chromene-7,8-diyl bis­(pent-4-ynoate)

    PubMed Central

    Akinyemi, Akintunde; Thomas, Courtney; Marsh, Willis; Butcher, Ray J.; Jasinski, Jerry P.; Maynard-Smith, Lystranne A.

    2016-01-01

    In the structures of the two title coumarin derivatives, C14H12O6, (1), and C20H16O6, (2), one with acetate and the other with pent-4-ynoate substituents, both the coumarin rings are almost planar. In (1), both acetate substituents are significantly rotated out of the coumarin plane to minimize steric repulsions. One acetate substituent is disordered over two equivalent conformations, with occupancies of 0.755 (17) and 0.245 (17). In (2), there are two pent-4-ynoate substituents, the C C group of one being disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). One of the pent-4-ynoate substituents is in an extended conformation, while the other is in a bent conformation. In this derivative, the planar part of both pent-4-ynoate substituents deviate from the coumarin plane. The packing of (1) is dominated by π–π stacking involving the coumarin rings and weak C—H⋯O contacts link the parallel stacks in the [101] direction. In contrast, in (2) the packing is dominated by R 2 2(24) hydrogen bonds, involving the acidic sp H atom and the oxo O atom, which link the mol­ecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in π–π stacking. PMID:27308023

  11. ROTATIONAL SPECTRUM AND TENTATIVE DETECTION OF DCOOCH{sub 3}-METHYL FORMATE IN ORION

    SciTech Connect

    Margules, L.; Huet, T. R.; Demaison, J.; Carvajal, M.; Kleiner, I.; Moellendal, H.; Tercero, B.; Marcelino, N.; Cernicharo, J. E-mail: jcernicharo@cab.inta-csic.e

    2010-05-10

    New centimeter-wave (7-80 GHz) and submillimeter-wave (580-661 GHz) spectra of a deuterated species of methyl formate (DCOOCH{sub 3}) have been measured. Transitions with a maximum value of J = 64 and K = 36 have been assigned and fitted together with previous measurements. The internal rotation of this compound was treated using the so-called rho axis method. A total of 1703 transitions were fitted using this method. Only 24 parameters were employed in the final fit, which has an rms deviation of 94.2 kHz. The dipole moment and the nuclear quadrupole coupling constants of the deuterated specie have also been obtained. This new study has permitted a tentative detection of DCOOCH{sub 3} in Orion with the IRAM 30 m telescope based on the observation of more than 100 spectral features with low blending effects among the 400 lines expected in the observed frequency domain (for which over 300 are heavily blended with other species). These 100 transitions are above noise and confusion limited without heavy blending and cannot be assigned to any other species. Moreover, none of the strongest unblended transitions is missing. The derived source-averaged total column density for DCOOCH{sub 3} is 7.8 x 10{sup 14} cm{sup -2} and the DCOOCH{sub 3}/HCOOCH{sub 3} column density ratio varies between 0.02 and 0.06 in the different cloud components of Orion. This value is consistent with the deuteration enhancement found for other species in this cloud.

  12. Effect of gibberellic acid (GA), indole acetic acid (IAA) and benzylaminopurine (BAP) on the synthesis of essential oils and the isomerization of methyl chavicol and trans-anethole in Ocimum gratissimum L.

    PubMed

    Hazzoumi, Zakaria; Moustakime, Youssef; Amrani Joutei, Khalid

    2014-01-01

    Basil (O. gratissimum L) is a aromatic and medicinal plant widely used in traditional medicine in Morocco. The aim of this work was to study the effect of three plant growth regulators gibberellic acid (GA), indole 3-acetic acid (IAA) and benzylaminopurine (BAP) on the content and composition of essential oils of this plant, especially on the main compound (methyl chavicol) and its isomer (the trans-anethole). The results showed a wide variation on yield, content and range of the molecule constituent of oil, with a balance of appearances and/or disappearances of a few molecules. GA caused a slight decrease in the oil yield (0.2%), but it increased the diversity of compounds (17 molecules) with the appearance of four new compounds (naphthalene, camphor, germacrene-D, and ledene) and disappearance of (β cedrene, azulene). This variation also caused a very important decrease in the main compound (methyl chavicol) and increases its isomer (trans-anethole). IAA and BAP caused an increase in the yield of essential oil (0.30% and 0.32% respectively) without much influence on the main compounds, but with some change in the composition such as the appearance of (germacrene-D) and the disappearance of (aristolene). PMID:25045609

  13. Chemistry of enol ethers. LXXIX. Reaction of glutaconaldehyde acetals and their derivatives with heterocyclic compounds. The synthesis of tricarbocyanine dyes

    SciTech Connect

    Makin, S.M.; Kruglikova, R.I.; Shavrygina, O.A.; Kolobova, T.P.; Popova, T.P.; Tagirov, T.K.

    1988-03-10

    The acetal forms of glutaconaldehyde (2,6-dialkoxypyrans, 1,1,5,5-tetraalkoxy-2-pentenes, 5,5-dialkoxy-2-pentenals, and 1,3,5,5-tetraalkoxy-1-pentenes) are capable of reacting with quaternary salts of heterocyclic bases containing an active methyl group in acetic anhydride solution and in the presence of triethylamine with the formation of tricarbocyanine dyes. Syntheses are reported of unsubstituted thio-, indo-, and quinotricarbocyanines and derivatives with various substituents in the polymethine chain. The reaction proceeds readily upon heating glutaconaldehyde derivatives with quaternary salts in acetic anhydride in the presence of triethylamine.

  14. Pit formation on poly(methyl methacrylate) due to ablation induced by individual slow highly charged ion impact

    NASA Astrophysics Data System (ADS)

    Ritter, R.; Wilhelm, R. A.; Ginzel, R.; Kowarik, G.; Heller, R.; El-Said, A. S.; Papaléo, R. M.; Rupp, W.; Crespo López-Urrutia, J. R.; Ullrich, J.; Facsko, S.; Aumayr, F.

    2012-01-01

    We report the formation of nano-sized pits on poly(methyl methacrylate) after exposure to slow highly charged ion beams. The pits are formed on the polymer surface as a direct result of individual ion impacts. Intermittent contact mode atomic-force microscopy was employed to study the size evolution of the pits in dependence of potential and kinetic energies of the incident ions. A potential energy threshold value of approximately 7 keV was found for pit formation. Above this value an increase in potential energy results in an increasing pit volume, while the pit shape can be tuned by varying the kinetic energy.

  15. Design, synthesis and biological activity of new amides derived from 3-methyl-3-phenyl-2,5-dioxo-pyrrolidin-1-yl-acetic acid.

    PubMed

    Obniska, Jolanta; Rapacz, Anna; Rybka, Sabina; Powroźnik, Beata; Pękala, Elżbieta; Filipek, Barbara; Żmudzki, Paweł; Kamiński, Krzysztof

    2015-09-18

    A series of new 3-methyl-3-phenyl-2,5-dioxo-pyrrolidin-1-yl-acetamides (6-23) has been synthesized and evaluated for their anticonvulsant activity in the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests after intraperitoneal injection in mice. The acute neurological toxicity was determined using the rotarod test. The in vivo preliminary pharmacological results showed that in the whole series only two compounds (15, 21) were devoid of activity, whereas other molecules revealed protection in at least one animal model of epilepsy (MES or/and scPTZ). The in vivo quantitative studies in mice showed that in the MES test the most active were 1-{2-[4-(2-methoxyphenyl)-piperazin-1-yl]-2-oxo-ethyl}-3-methyl-3-phenyl-pyrrolidine-2,5-dione (17), 1-{2-[4-(4-fluorophenyl)-piperazin-1-yl]-2-oxo-ethyl}-3-methyl-3-phenyl-pyrrolidine-2,5-dione (8), and its 2-fluorophenyl analog (7) with ED50 values of 97.51 mg/kg (17), 104.11 mg/kg (8), and 114.68 mg/kg (7), respectively. In the scPTZ screen the most potent were compound 6 with an ED50 = 40.87 mg/kg, and 4-benzylpiperidine derivative 22 - ED50 = 60.00 mg/kg. Furthermore, selected compounds 8, 14, 17, and 23 were tested in the psychomotor seizure 6-Hz test. Compounds 7, 8, and 17 revealed significant analgesic activity in the formalin model of tonic pain in mice, without impairment of the motor coordination in the chimney test. The in vitro binding studies showed that the mechanism of anticonvulsant activity may be partially related with the influence on the voltage-gated sodium and calcium channels. The mutagenic and antimutagenic effects of 13, 17, and 22 were evaluated using the novel Vibrio harveyi assay. PMID:26241874

  16. 2-Furaldehyde diethyl acetal from tender coconut water (Cocos nucifera) attenuates biofilm formation and quorum sensing-mediated virulence of Chromobacterium violaceum and Pseudomonas aeruginosa.

    PubMed

    Sethupathy, Sivasamy; Nithya, Chari; Pandian, Shunmugiah Karutha

    2015-01-01

    The aim of this study was to evaluate the anti-biofilm and quorum sensing inhibitory (QSI) potential of tender coconut water (TCW) against Chromobacterium violaceum and Pseudomonas aeruginosa. TCW significantly inhibited the QS regulated violacein, virulence factors and biofilm production without affecting their growth. qRT-PCR analysis revealed the down-regulation of autoinducer synthase, transcriptional regulator and virulence genes. Mass-spectrometric analysis of a petroleum ether extract of the TCW hydrolyte revealed that 2-furaldehyde diethyl acetal (2FDA) and palmitic acid (PA) are the major compounds. In vitro bioassays confirmed the ability of 2FDA to inhibit the biofilm formation and virulence factors. In addition, the combination of PA with 2FDA resulted in potent inhibition of biofilm formation and virulence factors. The results obtained strongly suggest that TCW can be exploited as a base for designing a novel antipathogenic drug formulation to treat biofilm mediated infections caused by P. aeruginosa. PMID:26571230

  17. Glutathione transferase activity and formation of macromolecular adducts in two cases of acute methyl bromide poisoning.

    PubMed Central

    Garnier, R; Rambourg-Schepens, M O; Müller, A; Hallier, E

    1996-01-01

    OBJECTIVES: To determine the activity of glutathione transferase and to measure the S-methylcysteine adducts in blood proteins, after acute inhalation exposure to methyl bromide. To examine the influence of the polymorphism of glutathione-S-transferase theta (GSTT1) on the neurotoxicity of methyl bromide. METHODS: Two workers acutely exposed to methyl bromide with inadequate respiratory protective devices were poisoned. Seven weeks after the accident, blood samples were drawn from both patients, for measurement of glutathione transferase activity in erythrocytes (conjugator status--that is, GSTT1 phenotype) and measurement of binding products of methyl bromide with blood proteins. Conjugator status was determined by a standard procedure. The binding product of methyl bromide, S-methylcysteine, was measured in globin and albumin. RESULTS: Duration and intensity of exposure were identical for both patients as they worked together with the same protective devices and with similar physical effort. However, one patient had very severe poisoning, whereas the other only developed mild neurotoxic symptoms. The first patient was a "conjugator" with normal glutathone transferase activity, whereas this activity was undetectable in the erythrocytes of the second patient, who consequently had higher concentrations of S-methylcysteine adduct in albumin (149 v 91 nmol/g protein) and in globin (77 v 30 nmol/g protein). CONCLUSIONS: Methyl bromide is genotoxic and neurotoxic. Its genotoxicity seems to be the consequence of the alkylating activity of the parent compound, and conjugation to glutathione has a protective effect. The data presented here suggest a different mechanism for methyl bromide neurotoxicity which could be related to the transformation of methylglutathione into toxic metabolites such as methanethiol and formaldehyde. If such metabolites are the ultimate toxic species, N-acetylcysteine treatment could have a toxifying rather than a detoxifying effect. PMID:8704864

  18. Ammonium acetate

    Integrated Risk Information System (IRIS)

    Ammonium acetate ; CASRN 631 - 61 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  19. Vinyl acetate

    Integrated Risk Information System (IRIS)

    Vinyl acetate ; CASRN 108 - 05 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  20. Ethyl acetate

    Integrated Risk Information System (IRIS)

    Ethyl acetate ; CASRN 141 - 78 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  1. Phenylmercuric acetate

    Integrated Risk Information System (IRIS)

    Phenylmercuric acetate ; CASRN 62 - 38 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  2. Thallium acetate

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 30 , 2009 , the assessment summary for Thallium acetate is included in t

  3. Didehydroaspartate Modification in Methyl-Coenzyme M Reductase Catalyzing Methane Formation.

    PubMed

    Wagner, Tristan; Kahnt, Jörg; Ermler, Ulrich; Shima, Seigo

    2016-08-26

    All methanogenic and methanotrophic archaea known to date contain methyl-coenzyme M reductase (MCR) that catalyzes the reversible reduction of methyl-coenzyme M to methane. This enzyme contains the nickel porphinoid F430 as a prosthetic group and, highly conserved, a thioglycine and four methylated amino acid residues near the active site. We describe herein the presence of a novel post-translationally modified amino acid, didehydroaspartate, adjacent to the thioglycine as revealed by mass spectrometry and high-resolution X-ray crystallography. Upon chemical reduction, the didehydroaspartate residue was converted into aspartate. Didehydroaspartate was found in MCR I and II from Methanothermobacter marburgensis and in MCR of phylogenetically distantly related Methanosarcina barkeri but not in MCR I and II of Methanothermobacter wolfeii, which indicates that didehydroaspartate is dispensable but might have a role in fine-tuning the active site to increase the catalytic efficiency. PMID:27467699

  4. A combined experimental and theoretical study of the tautomeric and conformational properties of (5-phenyl-tetrazol-2-yl)-acetic acid methyl ester.

    PubMed

    Saeed, Aamer; Qasim, Muhammad; Hussain, Majid; Flörke, Ulrich; Erben, Mauricio F

    2015-11-01

    The tautomeric and conformational properties of a new tetrazole derivative are studied in a combined approach that includes the analysis of the experimental vibrational data together with theoretical calculation methods, especially in terms of natural bond orbital (NBO) population analysis. Moreover, the molecular and crystal structure was determined by single crystal X-ray diffraction. The compound crystallized as the 2-tautomeric form, monoclinic space group P21/c with Z=4, a=10.0630(14), b=8.2879(11), c=12.8375(18) Å, β=105.546(3)°, V=1031.5(2) Å(3). The tetrazole and phenyl rings are coplanar with the acetate group oriented perpendicular to the plane. The NBO analysis showed that delocalizing interactions of the lpp(N2) lone pair orbital contributes to a strong resonance interactions with both adjacent π(∗)(N3N4) and π(∗)(N1C5) antibonding orbitals of the tetrazole group. PMID:26005846

  5. TIMASSS: the IRAS16293-2422 millimeter and submillimeter spectral survey: tentative detection of deuterated methyl formate (DCOOCH3)

    NASA Astrophysics Data System (ADS)

    Demyk, K.; Bottinelli, S.; Caux, E.; Vastel, C.; Ceccarelli, C.; Kahane, C.; Castets, A.

    2010-07-01

    Context. High deuterium fractionation is observed in various types of environments such as prestellar cores, hot cores, and hot corinos. It has proven to be an efficient probe for studying the physical and chemical conditions of these environments. The study of the deuteration of different molecules helps us to understand their formation. This is especially interesting for complex molecules like methanol and bigger molecules for which it may allow differentiation of gas-phase and solid-state formation pathways. Aims: Methanol exhibits a high deuterium fractionation in hot corinos. Since CH3OH is thought to be a precursor of methyl formate we expect that deuterated methyl formate is produced in such environments. We searched for the singly-deuterated isotopologue of methyl formate, DCOOCH3, in IRAS 16293-2422, a hot corino well-known for its high degree of methanol deuteration. Methods: We used the IRAM/JCMT unbiased spectral survey of IRAS 16293-2422, which allowed us to search for the DCOOCH3 rotational transitions within the survey spectral range (80-280 GHz, 328-366 GHz). The expected emission of deuterated methyl formate is modelled at LTE and compared with the observations. Results: We have tentatively detected DCOOCH3 in the protostar IRAS 16293-2422. We assign eight lines detected in the IRAM survey to DCOOCH3. Three of these lines are affected by blending problems, and one is affected by calibration uncertainties; nevertheless, the LTE emission model is compatible with the observations. A simple LTE modelling of the two cores in IRAS 16293-2422, based on a previous interferometric study of HCOOCH3, allows us to estimate the amount of DCOOCH3 in IRAS 16293-2422. Adopting an excitation temperature of 100 K and a source size of 2" and 1.5 arcsec for the A and B cores, respectively, we find that NA, DCOOCH3 = NB, DCOOCH3 ~ 6 × 1014 cm-2. The derived deuterium fractionation is ~15%, consistent with values for other deuterated species in this source and much

  6. Methyl Formate Oxidation: Speciation Data, Laminar Burning Velocities, Ignition Delay Times and a Validated Chemical Kinetic Model

    SciTech Connect

    Dooley, S.; Burke, M. P.; Chaos, M.; Stein, Y.; Dryer, F. L.; Zhukov, V. P.; Finch, O.; Simmie, J. M.; Curran, H. J.

    2010-07-16

    The oxidation of methyl formate (CH{sub 3}OCHO) has been studied in three experimental environments over a range of applied combustion relevant conditions: 1. A variable-pressure flow reactor has been used to quantify reactant, major intermediate and product species as a function of residence time at 3 atm and 0.5% fuel concentration for oxygen/fuel stoichiometries of 0.5, 1.0, and 1.5 at 900 K, and for pyrolysis at 975 K. 2. Shock tube ignition delays have been determined for CH{sub 3}OCHO/O{sub 2}/Ar mixtures at pressures of ≈ 2.7, 5.4, and 9.2 atm and temperatures of 1275–1935 K for mixture compositions of 0.5% fuel (at equivalence ratios of 1.0, 2.0, and 0.5) and 2.5% fuel (at an equivalence ratio of 1.0). 3. Laminar burning velocities of outwardly propagating spherical CH{sub 3}OCHO/air flames have been determined for stoichiometries ranging from 0.8–1.6, at atmospheric pressure using a pressure-release-type high-pressure chamber. A detailed chemical kinetic model has been constructed, validated against, and used to interpret these experimental data. The kinetic model shows that methyl formate oxidation proceeds through concerted elimination reactions, principally forming methanol and carbon monoxide as well as through bimolecular hydrogen abstraction reactions. The relative importance of elimination versus abstraction was found to depend on the particular environment. In general, methyl formate is consumed exclusively through molecular decomposition in shock tube environments, while at flow reactor and freely propagating premixed flame conditions, there is significant competition between hydrogen abstraction and concerted elimination channels. It is suspected that in diffusion flame configurations the elimination channels contribute more significantly than in premixed environments.

  7. Unexpected ring-closure products derived from 3-(2-allylanilino)-3-phenylacrylate esters: crystal and molecular structures of 3-acetyl-8-allyl-6-methyl-2-phenylquinolin-4-yl acetate and (2RS)-2,8-dimethyl-4-phenyl-1,2-dihydro-6H-pyrrolo[3,2,1-ij]quinolin-6-one.

    PubMed

    Luque, Adriana L; Sanabria, Carlos M; Palma, Alirio; Cobo, Justo; Glidewell, Christopher

    2016-08-01

    The reactions of two 3-(2-allylanilino)-3-phenylacrylate esters with acetic anhydride and with strong acids has revealed a richly diverse reactivity providing a number of unexpected products. Thus, acetylation of ethyl 3-(2-allylanilino)-3-phenylacrylate, (Ia), or ethyl 3-(2-allyl-4-methylanilino)-3-phenylacrylate, (Ib), with acetic anhydride yields not only the expected acetylated esters, (II), as the major products but also the unexpected polysubstituted quinolines 3-acetyl-8-allyl-2-phenylquinolin-4-yl acetate, (IIIa), and 3-acetyl-8-allyl-6-methyl-2-phenylquinolin-4-yl acetate, (IIIb), as minor products. Subsequent reaction of the major product ethyl 2-[(2-allyl-4-methylanilino)(phenyl)methylidene]-3-oxobutanoate, (IIb), with concentrated sulfuric acid did not provide the expected 3-acetylquinoline derivative, but instead two unexpected products, namely ethyl 4-ethyl-2-phenyl-1,4-dihydroquinoline-3-carboxylate, (IV), and ethyl 3-acetyl-4-ethyl-2-phenyl-3,4-dihydroquinoline-3-carboxylate, (V), in yields of 39 and 22%, respectively. The reaction of (Ib) with Eaton's reagent gave both the quinoline (Z)-6-methyl-2-phenyl-8-(prop-1-en-1-yl)quinolin-4(1H)-one, (VI), and the unexpected tricyclic product (2RS)-2,8-dimethyl-4-phenyl-1,2-dihydro-6H-pyrrolo[3,2,1-ij]quinolin-6-one, (VII), in yields of 71 and 12%, respectively. The products (II)-(VII) have all been fully characterized spectroscopically and the crystal structures of two of the unexpected products, i.e. (IIIb) (C23H21NO3) and (VII) (C19H17NO), are reported here. The formation of compounds (IV), (V) and (VII) all require an isomerization of the initial allyl substituent, with migration of the C=C double bond from the terminal site to the internal site. In (IIIb), the two acetyl substituents are oriented such that the intramolecular distance between the two carbonyl O atoms is only 3.243 (2) Å, and in (VII), the five-membered ring adopts a twisted half-chair conformation. The molecules of compound (IIIb

  8. Weak maser emission of methyl formate toward Sagittarius B2(N) in the green bank telescope PRIMOS survey

    SciTech Connect

    Faure, A.; Wiesenfeld, L.; Szalewicz, K.

    2014-03-10

    A non-LTE radiative transfer treatment of cis-methyl formate (HCOOCH{sub 3}) rotational lines is presented for the first time using a set of theoretical collisional rate coefficients. These coefficients have been computed in the temperature range 5-30 K by combining coupled-channel scattering calculations with a high accuracy potential energy surface for HCOOCH{sub 3}-He. The results are compared to observations toward the Sagittarius B2(N) molecular cloud using the publicly available PRIMOS survey from the Green Bank Telescope. A total of 49 low-lying transitions of methyl formate, with upper levels below 25 K, are identified. These lines are found to probe a presumably cold (∼30 K), moderately dense (∼10{sup 4} cm{sup –3}), and extended region surrounding Sgr B2(N). The derived column density of ∼4 × 10{sup 14} cm{sup –2} is only a factor of ∼10 larger than the column density of the trans conformer in the same source. Provided that the two conformers have the same spatial distribution, this result suggests that strongly non-equilibrium processes must be involved in their synthesis. Finally, our calculations show that all detected emission lines with a frequency below 30 GHz are (collisionally pumped) weak masers amplifying the continuum of Sgr B2(N). This result demonstrates the importance and generality of non-LTE effects in the rotational spectra of complex organic molecules at centimeter wavelengths.

  9. Copper-catalyzed aerobic oxidation and cleavage/formation of C-S bond: a novel synthesis of aryl methyl sulfones from aryl halides and DMSO.

    PubMed

    Yuan, Gaoqing; Zheng, Junhua; Gao, Xiaofang; Li, Xianwei; Huang, Liangbin; Chen, Huoji; Jiang, Huanfeng

    2012-08-01

    With atmospheric oxygen as the oxidant, a novel copper(I)-catalyzed synthesis of aryl methyl sulfones from aryl halides and widely available DMSO is described. The procedure tolerates aryl halides with various functional groups (such as methoxy, acetyl, chloro, fluoro and nitro groups), which could afford aryl methyl sulfones in moderate to high yields. The copper-catalyzed aerobic oxidation and the cleavage/formation of C-S bond are the key steps for this transformation. PMID:22728918

  10. A Metabolic Shift toward Pentose Phosphate Pathway Is Necessary for Amyloid Fibril- and Phorbol 12-Myristate 13-Acetate-induced Neutrophil Extracellular Trap (NET) Formation.

    PubMed

    Azevedo, Estefania P; Rochael, Natalia C; Guimarães-Costa, Anderson B; de Souza-Vieira, Thiago S; Ganilho, Juliana; Saraiva, Elvira M; Palhano, Fernando L; Foguel, Debora

    2015-09-01

    Neutrophils are the main defense cells of the innate immune system. Upon stimulation, neutrophils release their chromosomal DNA to trap and kill microorganisms and inhibit their dissemination. These chromatin traps are termed neutrophil extracellular traps (NETs) and are decorated with granular and cytoplasm proteins. NET release can be induced by several microorganism membrane components, phorbol 12-myristate 13-acetate as well as by amyloid fibrils, insoluble proteinaceous molecules associated with more than 40 different pathologies among other stimuli. The intracellular signaling involved in NET formation is complex and remains unclear for most tested stimuli. Herein we demonstrate that a metabolic shift toward the pentose phosphate pathway (PPP) is necessary for NET release because glucose-6-phosphate dehydrogenase (G6PD), an important enzyme from PPP, fuels NADPH oxidase with NADPH to produce superoxide and thus induce NETs. In addition, we observed that mitochondrial reactive oxygen species, which are NADPH-independent, are not effective in producing NETs. These data shed new light on how the PPP and glucose metabolism contributes to NET formation. PMID:26198639

  11. A Metabolic Shift toward Pentose Phosphate Pathway Is Necessary for Amyloid Fibril- and Phorbol 12-Myristate 13-Acetate-induced Neutrophil Extracellular Trap (NET) Formation*

    PubMed Central

    Azevedo, Estefania P.; Rochael, Natalia C.; Guimarães-Costa, Anderson B.; de Souza-Vieira, Thiago S.; Ganilho, Juliana; Saraiva, Elvira M.; Palhano, Fernando L.; Foguel, Debora

    2015-01-01

    Neutrophils are the main defense cells of the innate immune system. Upon stimulation, neutrophils release their chromosomal DNA to trap and kill microorganisms and inhibit their dissemination. These chromatin traps are termed neutrophil extracellular traps (NETs) and are decorated with granular and cytoplasm proteins. NET release can be induced by several microorganism membrane components, phorbol 12-myristate 13-acetate as well as by amyloid fibrils, insoluble proteinaceous molecules associated with more than 40 different pathologies among other stimuli. The intracellular signaling involved in NET formation is complex and remains unclear for most tested stimuli. Herein we demonstrate that a metabolic shift toward the pentose phosphate pathway (PPP) is necessary for NET release because glucose-6-phosphate dehydrogenase (G6PD), an important enzyme from PPP, fuels NADPH oxidase with NADPH to produce superoxide and thus induce NETs. In addition, we observed that mitochondrial reactive oxygen species, which are NADPH-independent, are not effective in producing NETs. These data shed new light on how the PPP and glucose metabolism contributes to NET formation. PMID:26198639

  12. Poly (methyl methacrylate) Formation and Patterning Initiated by Synchrotron X-ray Illumination

    SciTech Connect

    Xiao, J.; Je, J. H.; Wang, C. H.; Yang, T. Y.; Hwu, Y.

    2007-01-19

    A facile radiation method was developed to obtain micro-sized poly (methyl methacrylate) (PMMA) particles and create patterned coating on different substrates by a synchrotron x-ray induced dispersion polymerization. The polymerization of MMA monomer and well defined patterning was successfully realized. The produced PMMA particles and patterning were characterized by Fourier transformation infrared (FTIR), 1H-Nuclear Magnetic Resonance (NMR), and Scanning Electron Microscope (SEM). The observed patterning contrast essentially derived from a variation of size, density and morphology of particles and the type of substrate materials used.

  13. Acet-oxy-γ-valerolactone.

    PubMed

    Tristram, Cameron; Gainsford, Graeme J; Hinkley, Simon

    2013-06-01

    Levulinyl cellulose esters have been produced as an effective renewable binder for architectural coatings. The title compound, C7H10O4 (systematic name: 2-methyl-5-oxo-tetra-hydro-furan-2-yl acetate), assigned as the esterifying species, was isolated and crystallized to confirm the structure. In the crystal, the mol-ecules pack in layers parallel to (102) utilizing weak C-H⋯O inter-actions. PMID:23795112

  14. Surface structures of poly(methyl methacrylate) films influenced by chain entanglement in the corresponding film-formation solution.

    PubMed

    Xu, Jianquan; Liu, Yingjun; He, Jinsheng; Zhang, Rongping; Zuo, Biao; Wang, Xinping

    2014-11-28

    The effects of the properties of casting solution on the surface structure of poly(methyl methacrylate) (PMMA) films were systematically investigated. It was observed that the hydrophobicity of PMMA films increased with increasing viscosity of the corresponding polymer solution regardless of the film-formation techniques that were utilized. The ratio of the C-H symmetric stretching vibrations of methylene groups (hydrophobic components, with a peak at 2910 cm(-1)) to those of the ester methyl groups (relative hydrophilic components, with a peak at 2955 cm(-1)) from sum frequency generation (SFG) vibrational spectra, A2910/A2955, was used as a parameter to evaluate the structure on the film surface, which was related to the surface wettability of the films. The results showed that A2910/A2955 of cast PMMA films increased linearly with ηsp(0.3) (ηsp, the specific viscosity of the casting solution), whereas that of the corresponding spin-coated films showed a linear relationship defined as ηsp(0.3)E(0.26), where E is the average number of entanglement points per molecule (E = Mw/Me). These results indicate that a relative equilibrium conformation on the PMMA film surface, adopted from the perspective of thermodynamics, was easily achieved during film formation, when the conformation of the polymer chains in the corresponding casting solution was close to that in the bulk. For the spin-coated films, the chain entanglement structure in the casting solution was a more important factor for the resulting film to reach a relative equilibrium state, since this structure was in favor of maintaining the pristine conformation in casting solution under centrifugal force during spin-coating. This work may help to enhance the fundamental understanding of the formation of the film surface structure from polymer solution to the resulting solid film, which will affect not only the corresponding surface properties, but also the dynamics of the resulting thin films. PMID:25295969

  15. Synthesis of cyclic acetals (ketals) from oleochemicals using a solvent free method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have studied the reaction selectivities of acid catalyzed ring opening reactions of epoxidized methyl oleate (methyl 9,10-epoxy stearate; EMO), to form either acetal or branched ester products. We have produced: methyl 9-(2-butyl-2-methyl-5-octyl-1,3-dioxolan-4-yl) nonanoate (hexanone methyl st...

  16. Selective formation of organo, organo-aqueous, and hydro gel-like materials from partially hydrolysed poly(vinyl acetate)s based on different boron-containing crosslinkers.

    PubMed

    Angelova, L V; Leskes, M; Berrie, B H; Weiss, R G

    2015-07-01

    Viscoelastic, gel-like, polymeric dispersions (HVPDs) can be prepared by crosslinking polyols with borax or boric acid in water under alkaline conditions. Rheologically similar HVPDs have been prepared in organic liquids containing no water or hydroxylic groups through crosslinking partially or fully hydrolysed poly(vinyl acetate)s with trimethyl borate, boric acid, or borax. The organo-HVPDs are water-sensitive and rheoreversible on exposure to water. They were characterised rheologically and by solution and solid-state (11)B NMR spectroscopy. Spectroscopic analyses show the presence of mono- and di-diol crosslinks, as well as non-crosslinked boron species in HVPDs prepared with trimethyl borate or boric acid. The number of crosslinks in organo-HVPDs prepared with borax increased over the course of several days. Results from solution and solid-state (11)B NMR spectroscopy are comparable; no solid-like component was detectable. We demonstrate that hydro, organo, or organo-aqueous HVPDs can be obtained from partially hydrolysed poly(vinyl acetate)s by 'tuning' the structure of the boron-based crosslinker. PMID:26027551

  17. Influence of the linkage type between the polymer backbone and side groups on the surface segregation of methyl groups during film formation.

    PubMed

    Zhang, Yizhi; Fan, Hao; Wang, Yuping; Zuo, Biao; Zhang, Wei; Wang, Shunli; Wang, Xinping

    2015-12-21

    Although poly(vinyl acetate) (PVAc) differs from poly(methyl acrylate) (PMA) only in the reversed position of the ester group, a large difference in the concentration dependence of the casting solution on the corresponding surface structure of the cast films of PVAc, PMA and poly(methyl methacrylate) (PMMA) was observed. The hydrophobicity of both PMA and PMMA films increased with increasing concentration of the corresponding polymer solution, whereas cast PVAc films showed the reverse trend. The surface structure of the cast films prepared with different concentrations of the casting solution, characterized by sum frequency generation (SFG) vibrational spectra, showed that the order of the methylene groups increased while that of the acetyl methyl group decreased on the surface of cast PVAc film with increasing concentration of casting solution. However, the order of the ester methyl group increased and that of methylene groups did not change for cast PMA films with increasing concentration of casting solution. The cast PMMA film showed a reverse trend compared with the corresponding PMA film. It is apparent that well-ordered ester or acetyl methyl groups on the surface, which are oriented away from the polymer film, rather than methylene groups, play an important role in determining surface hydrophobicity, as the latter shield the OC[double bond, length as m-dash]O groups of PVAc, PMA and PMMA film surfaces from being exposed, resulting in low surface free energy. The reason for this difference is attributed to the relatively low energy for ester methyl group reorientation, an ester group structure nearer to the trans state and more regular local configuration of segments in concentrated solutions of PMA and PMMA compared to that of PVAc. PMID:26415634

  18. Study on the growth and photosynthetic characteristics of wheat seedlings under [C₄mim][OAc] (1-butyl-3-methyl-imidazolium acetate) with Cd²⁺ stress.

    PubMed

    Chen, Zhonglin; Feng, Yingying; Wang, Yan; Li, Yue; Liu, Qiang; Xu, Sunan; Guan, Wei

    2015-05-01

    In this paper, the joint effect of 0.5 mmol·L(-1) Cd(2+) and various concentrations (50-400 mg·L(-1)) of the ionic liquid 1-butyl-3-methyl-imidazolium acetate ([C4min][OAc]) on the growth and photosynthetic performance of wheat seedlings in hydroponic culture was investigated. Seedlings grown in presence of Cd(2+) and [C4min][OAc] showed significant (p < 0.05) improvement in growth (shoot and root lengths and dry weights) and photosynthetic performance (photosynthetic rate, stomatal conductance, transpiration rate, and chlorophyll a but not chlorophyll b) compared to seedlings grown in the presence of Cd(2+) but without [C4min][OAc]. However, this only happened under the lower range of [C4min][OAc] concentrations (50-200 mg·L(-1)). In addition, significant reduction in the level of Cd(2+) was also observed in the leaf tissue of wheat seedlings grown in the presence of 0.5 mmol·L(-1) Cd(2+) and 100 mg·L(-1) [C4min][OAc]. Overall, Cd(2+) exerted a stronger inhibition than [C4min][OAc] on the growth and photosynthetic performance of wheat seedlings. However, when both Cd(2+) and [C4min][OAc] were present in the culture, the toxicity of Cd(2+) could be mitigated by lower concentrations of [C4mim][OAc]. This phenomenon could be due to [C4mim][OAc] forming metal complexes with Cd(2+), thus reducing the toxicity of Cd(2+). PMID:25778420

  19. Molecular interactions in binary mixtures of methyl formate with 1-butanol, 1-pentanol, and 1-hexanol by using ultrasonic data at 303 K

    NASA Astrophysics Data System (ADS)

    Elangovan, S.; Mullainathan, S.

    2016-05-01

    Density (ρ), viscosity (η), and ultrasonic velocity ( U) have been measured for binary mixtures of methyl formate with 1-butanol, 1-pentanol and 1-hexanol at 303 K. From the experimental results, adiabatic compressibility (β), acoustic impedance ( Z), viscous relaxation time (τ), free length ( L f), free volume ( V f), internal pressure (πi), and Gibbs free energy (Δ G) have been determined. Excess values of various parameters have also been calculated and interoperated in terms of molecular interactions. The deviations in the parameters show that strength of intermolecular interactions between methyl formate with selected 1-alcohols have been observed in the order of 1-butanol < 1-pentanol < 1-hexanol.

  20. Formation of a periodic diffractive structure based on poly(methyl methacrylate) with ion-implanted silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Galyautdinov, M. F.; Nuzhdin, V. I.; Fattakhov, Ya. V.; Farrakhov, B. F.; Valeev, V. F.; Osin, Yu. N.; Stepanov, A. L.

    2016-02-01

    We propose to form optical diffractive elements on the surface of poly(methyl methacrylate) (PMMA) by implanting the polymer with silver ions ( E = 30 keV; D = 5.0 × 1014 to 1.5 × 1017 ion/cm2; I = 2 μA/cm2) through a nickel grid (mask). Ion implantation leads to the nucleation and growth of silver nanoparticles in unmasked regions of the polymer. The formation of periodic surface microstructures during local sputtering of the polymer by incident ions was monitored using an optical microscope. The diffraction efficiency of obtained gratings is demonstrated under conditions of their probing with semiconductor laser radiation in the visible spectral range.

  1. Intermolecular interactions in methyl formate-ethanol mixtures at 303-313 K according to ultrasonic data

    NASA Astrophysics Data System (ADS)

    Elangovan, S.; Mullainathan, S.

    2014-04-01

    Density (ρ), viscosity (η), and ultrasonic velocity ( U) have been measured for a binary mixture composed of methyl formate and ethanol at 303, 308, and 313 K. The adiabatic compressibility (β), acoustic impedance (Z), free length ( L f ), free volume ( V f ), internal pressure (π i ), viscous relaxation time (τ), and Gibbs free energy (Δ G) were calculated from the experimental data. The excess values of these parameters (β E , Z E , L {/f E }, V {/f E }, π {/i E }, τ E , and Δ G E ) have also been calculated using the determined parameters and interpreted in terms of molecular interactions. The deviations in the sign and values of these excess parameters from the ideal mixing reveal the nature of intermolecular interactions between components of the mixture.

  2. Trivalent methylated arsenical-induced phosphatidylserine exposure and apoptosis in platelets may lead to increased thrombus formation

    SciTech Connect

    Bae, Ok-Nam; Lim, Kyung-Min; Chung, Jin-Ho

    2009-09-01

    Trivalent methylated metabolites of arsenic, monomethylarsonous acid (MMA{sup III}) and dimethylarsinous acid (DMA{sup III}), have been found highly reactive and toxic in various cells and in vivo animal models, suggesting their roles in the arsenic-associated toxicity. However, their effects on cardiovascular system including blood cells, one of the most important targets for arsenic toxicity, remain poorly understood. Here we found that MMA{sup III} and DMA{sup III} could induce procoagulant activity and apoptosis in platelets, which play key roles in the development of various cardiovascular diseases (CVDs) through excessive thrombus formation. In freshly isolated human platelets, treatment of MMA{sup III} resulted in phosphatidylserine (PS) exposure, a hallmark of procoagulant activation, accompanied by distinctive apoptotic features including mitochondrial membrane potential disruption, cytochrome c release, and caspase-3 activation. These procoagulant activation and apoptotic features were found to be mediated by the depletion of protein thiol and intracellular ATP, and flippase inhibition by MMA{sup III}, while the intracellular calcium increase or reactive oxygen species generation was not involved. Importantly, increased platelet procoagulant activity by MMA{sup III} resulted in enhanced blood coagulation and excessive thrombus formation in a rat in vivo venous thrombosis model. DMA{sup III} also induced PS-exposure with apoptotic features mediated by protein thiol depletion, which resulted in enhanced thrombin generation. In summary, we believe that this study provides an important evidence for the role of trivalent methylated arsenic metabolites in arsenic-associated CVDs, giving a novel insight into the role of platelet apoptosis in toxicant-induced cardiovascular toxicity.

  3. Anaerobic biodegradation of methyl esters by Acetobacterium woodii and Eubacterium limosum.

    PubMed

    Liu, S; Suflita, J M

    1994-09-01

    The ability of Acetobacterium woodii and Eubacterium limosum to degrade methyl esters of acetate, propionate, butyrate, and isobutyrate was examined under growing and resting-cell conditions. Both bacteria hydrolyzed the esters to the corresponding carboxylates and methanol under either condition. Methanol was further oxidized to formate under growing but not resting conditions. Unlike the metabolism of phenylmethylethers, no H2 requirement was evident for ester biotransformation. The hydrolysis of methyl carboxylates is thermodynamically favorable under standard conditions and the mixotrophic metabolism of ester/CO2 allowed for bacterial growth. These results suggest that the degradation of methyl carboxylates may be a heretofore unrecognized nutritional option for acetogenic bacteria. PMID:7765371

  4. Aqueous SOA formation from radical oligomerization of methyl vinyl ketone (MVK) and methacrolein (MACR)

    NASA Astrophysics Data System (ADS)

    Renard, P.; Siekmann, F.; Ravier, S.; Temime-Roussel, B.; Clément, J.; Ervens, B.; Monod, A.

    2013-12-01

    It is now accepted that one of the important pathways of secondary organic aerosol (SOA) formation occurs through aqueous phase chemistry in the atmosphere. However, the chemical mechanisms leading to macromolecules are still not well understood. It was recently shown that oligomer production by OH radical oxidation in the aerosol aqueous phase from α-dicarbonyl precursors, such as methylglyoxal and glyoxal, is irreversible and fast. We have investigated the aqueous phase photooxidation of MACR and MVK, which are biogenic organic compounds derived from isoprene. Aqueous phase photooxidation of MVK and MACR was investigated in a photoreactor using photolysis of H2O2 as OH radical source. Electrospray high resolution mass spectrometry analysis of the solutions brought clear evidence for the formation of oligomer systems having a mass range of up to 1800 Da within less than 15 minutes of reaction. Highest oligomer formation rates were obtained under conditions of low dissolved oxygen, highest temperature (T = 298 K) and highest precursor initial concentrations ([MVK]0 = 20 mM). A radical mechanism of oligomerization is proposed to explain the formation of the high molecular weight products. Furthermore, we quantified the total amount of carbon present in oligomers. Kinetic parameters of the proposed oligomerization mechanism are constrained by means of a box model that is able to reproduce the temporal evolution of intermediates and products as observed in the laboratory experiments. Additional model simulations for atmospherically-relevant conditions will be presented that show the extent to which these radical processes contribute to SOA formation in the atmospheric multiphase system as compared to other aqueous phase as well as traditional SOA sources. MVK time profile (as measured by UV Spectroscopy) and mass spectra (obtained using UPLC-ESI-MS for the retention time range 0-5 min in the positive mode) at 5, 10 and 50 min of reaction (MVK 20 mM, 25° C, under

  5. {2-[1-(3-Methoxycarbonylmethyl-1H-indol-2-yl)-1-methyl-ethyl]-1H-indol-3-yl}-acetic Acid Methyl Ester Inhibited Hepatocellular Carcinoma Growth in Bel-7402 Cells and Its Resistant Variants by Activation of NOX4 and SIRT3.

    PubMed

    Li, Ye; Wang, Wenjing; Xu, Xiaoxue; Sun, Shiyue; Xu, Xiaoyu; Qu, Xian-jun

    2015-01-01

    {2-[1-(3-Methoxycarbonylmethyl-1H-indol-2-yl)-1-methyl-ethyl]-1H-indol-3-yl}-acetic acid methyl ester (MIAM) is a novel indole compound, which possessed high efficacy against many cancers xenografted in mice without obvious toxicity. In this study, we aimed to investigate the effects of MIAM on human hepatocellular carcinoma (HCC) Bel-7402 cells and its resistant variants Bel-7402/5FU. MIAM inhibited the growth of HCC more potent in Bel-7402/5FU cells than its parent cells. MIAM increased cellular reactive oxygen species (ROS) levels, induced cell apoptosis, and arrested cell cycle in G0/G1 phase. MIAM might exert its action on Bel-7402/5FU cells through activation of NADPH oxidase 4 (NOX4)/p22(phox), Sirtuin3 (SIRT3)/SOD2, and SIRT3/p53/p21(Waf1/Cip) pathways. MIAM might inhibit HCC growth through the modulation of SIRT3. When SIRT3 was silenced, the inhibitory effect of MIAM on Bel-7402/5FU was lowered, showing the characteristic of resistance against MIAM, whereas Bel-7402/5FU cells with high expression of SIRT3 by SIRT3 adenovirus infection demonstrated the high sensitivity to MIAM. These results suggested that MIAM might exert its action against Bel-7402/5FU growth through upregulation of SIRT3. We suggested that MIAM might be a promising candidate compound which could develop as a potent anticancer agent targeting NOX4 and SIRT3 activation. PMID:25961022

  6. {2-[1-(3-Methoxycarbonylmethyl-1H-indol-2-yl)-1-methyl-ethyl]-1H-indol-3-yl}-acetic Acid Methyl Ester Inhibited Hepatocellular Carcinoma Growth in Bel-7402 Cells and Its Resistant Variants by Activation of NOX4 and SIRT3

    PubMed Central

    Li, Ye; Wang, Wenjing; Xu, Xiaoxue; Sun, Shiyue; Xu, Xiaoyu; Qu, Xian-jun

    2015-01-01

    {2-[1-(3-Methoxycarbonylmethyl-1H-indol-2-yl)-1-methyl-ethyl]-1H-indol-3-yl}-acetic acid methyl ester (MIAM) is a novel indole compound, which possessed high efficacy against many cancers xenografted in mice without obvious toxicity. In this study, we aimed to investigate the effects of MIAM on human hepatocellular carcinoma (HCC) Bel-7402 cells and its resistant variants Bel-7402/5FU. MIAM inhibited the growth of HCC more potent in Bel-7402/5FU cells than its parent cells. MIAM increased cellular reactive oxygen species (ROS) levels, induced cell apoptosis, and arrested cell cycle in G0/G1 phase. MIAM might exert its action on Bel-7402/5FU cells through activation of NADPH oxidase 4 (NOX4)/p22phox, Sirtuin3 (SIRT3)/SOD2, and SIRT3/p53/p21Waf1/Cip pathways. MIAM might inhibit HCC growth through the modulation of SIRT3. When SIRT3 was silenced, the inhibitory effect of MIAM on Bel-7402/5FU was lowered, showing the characteristic of resistance against MIAM, whereas Bel-7402/5FU cells with high expression of SIRT3 by SIRT3 adenovirus infection demonstrated the high sensitivity to MIAM. These results suggested that MIAM might exert its action against Bel-7402/5FU growth through upregulation of SIRT3. We suggested that MIAM might be a promising candidate compound which could develop as a potent anticancer agent targeting NOX4 and SIRT3 activation. PMID:25961022

  7. A Search for Interstellar Acetic Acid Using the BIMA and OVRO Millimeter Arrays

    NASA Astrophysics Data System (ADS)

    Mehringer, D. M.; Snyder, L. E.; Miao, Y.; Lovas, F. J.

    1996-03-01

    We have used the Berkeley-Illinois-Maryland Association (BIMA) and the Caltech Owens Valley (OVRO) millimeter arrays to search for acetic acid (CH_3COOH) in the Sgr B2 Large Molecule Heimat source (e.g., Miao et al. 1995, ApJ, 445, L59). With the BIMA Array, we observed two transitions near 90 GHz. One of these lines is blended with the 37_{8,29} ->37_{8,30} line of methyl formate,(HCOOCH_3) and so an unambiguous identification is difficult. The other line is in a clear spectral region and we have a detection at the 5 sigma level. In order to confirm that this line is due to acetic acid, we have used the OVRO Millimeter Array to search for another pair of acetic acid lines near 100 GHz. These data are currently being reduced, and we will discuss our results.

  8. Effects of Trophic Status on Mercury Methylation Pathways in Peatlands

    NASA Astrophysics Data System (ADS)

    Hines, M. E.; Zhang, L.; Sampath, S.; Hu, R.; Barkay, T.

    2014-12-01

    Methyl mercury (MeHg) is a bioaccumulative toxicant. It was believed to be produced by sulfate (SO4)- and iron- reducing bacteria (SRB and FeRB), but recent studies suggest that organisms that possess the gene cluster (hgcAB) can methylate Hg, which includes other microbial groups besides SRB and FeRB. Many areas known to accumulate high levels of MeHg are freshwater wetlands that lack sufficient electron acceptors to support the production of MeHg. To test the hypothesis that oligotrophic wetlands are able to methylate Hg by pathways that are not respiratory, peat was collected from three wetland sites in Alaska and three in Massachusetts that represented a trophic gradient. We determined rates of gas (CH4, CO2, H2) and LMW organic acid (formate, acetate, propionate, butyrate) formation, and rates of Hg methylation using the short-lived radioisotope 197Hg (half life 2.67 days). Two temperate sites exhibited strong terminal respiration (methanogenesis) and syntrophy, while the Alaskan sites and an oligotrophic temperate site exhibited low rates of both. Primary fermentation was an important process in the latter sites. Hg methylation was most active at the minerotrophic sites that exhibited active syntrophy and methanogenesis. Methylation decreased greatly in the presence of a methanogenic inhibitor and was stimulated by H2 indicating that methanogens and perhaps syntrophs were primary methylators. In the oligotrophic sites, the addition of SO4 stimulated methylation while a SO4 reduction inhibitor decreased methylation. There was no evidence of SO4 reduction in these samples suggesting that methylation was conducted by SRB that were metabolizing via fermentation and not SO4 reduction. While further studies are required to decipher the role of syntrophs including SRB varieties such as Syntrophobacter sp., these results indicate that fermentative bacteria may be able to significantly methylate Hg in wetlands that do not support anaerobic respiration.

  9. Instability of chromosome number and DNA methylation variation induced by hybridization and amphidiploid formation between Raphanus sativus L. and Brassica alboglabra Bailey

    PubMed Central

    2010-01-01

    Background Distant hybridization can result genome duplication and allopolyploid formation which may play a significant role in the origin and evolution of many plant species. It is unclear how the two or more divergent genomes coordinate in one nucleus with a single parental cytoplasm within allopolyploids. We used cytological and molecular methods to investigate the genetic and epigenetic instabilities associated with the process of distant hybridization and allopolyploid formation, measuring changes in chromosome number and DNA methylation across multiple generations. Results F1 plants from intergeneric hybridization between Raphanus sativus L. (2n = 18, RR) and Brassica alboglabra Bailey (2n = 18, CC) were obtained by hand crosses and subsequent embryo rescue. Random amplification of polymorphic DNA (RAPD) markers were used to identify the F1 hybrid plants. The RAPD data indicated that the hybrids produced specific bands similar to those of parents and new bands that were not present in either parent. Chromosome number variation of somatic cells from allotetraploids in the F4 to F10 generations showed that intensive genetic changes occurred in the early generations of distant hybridization, leading to the formation of mixopolyploids with different chromosome numbers. DNA methylation variation was revealed using MSAP (methylation-sensitive amplification polymorphism), which showed that cytosine methylation patterns changed markedly in the process of hybridization and amphidiploid formation. Differences in cytosine methylation levels demonstrated an epigenetic instability of the allopolyploid of Raphanobrassica between the genetically stable and unstable generations. Conclusions Our results showed that chromosome instability occurred in the early generations of allopolyploidy and then the plants were reverted to largely euploidy in later generations. During this process, DNA methylation changed markedly. These results suggest that, epigenetic mechanisms play an

  10. SOA Formation from the Atmospheric Oxidation of 2-Methyl-3-Buten-2-ol and Its Implications for PM2.5

    EPA Science Inventory

    The formation of secondary organic aerosol (SOA) generated by irradiating 2-methyl-3-buten-2-01 (MBO) in the presence and/or absence of NOx H2O2, and/or SO2 was examined. Experiments were conducted. in smog chambers operated either in dyna....

  11. The formation of SOA and chemical tracer compounds from the photooxidation of naphthalene and its methyl analogs in the presence and absence of nitrogen oxides

    EPA Science Inventory

    Laboratory smog chamber experiments have been carried out to investigate secondary organic aerosol (SOA)formation from the photooxidation of naphthalene and its methyl analogs, 1- and 2-methylnaphthalene (1-MN and 2- MN, respectively). Laboratory smog chamber irradiations were co...

  12. Tyrosine kinase inhibitor, methyl 2,5-dihydromethylcinnimate, induces PML nuclear body formation and apoptosis in tumor cells

    SciTech Connect

    Komura, Naoyuki; Asakawa, Mayako; Umezawa, Kazuo . E-mail: umezawa@applc.keio.ac.jp; Segawa, Kaoru

    2007-08-01

    Promyelocytic leukemia (PML) nuclear bodies (PML-NBs) are the nuclear structure consisting of various proteins such as PML, SUMO-1, and p53. PML-NBs are implicated in the regulation of tumor suppression, antiviral responses, and apoptosis. In this study, we searched for bioactive metabolites that would promote the formation of PML-NBs in tumor cells. As a result, methyl 2,5-dihydromethylcinnimate (2,5-MeC), a tyrosine kinase inhibitor, enhanced expression and/or stability of PML proteins and induced PML-NB formation in p53 null H1299 cells established from non-small cell lung cancer (NSCLC) and wild-type p53-expressing U2OS cells derived from osteosarcoma. Furthermore, it enhanced apoptosis by exogenously expressed wild type p53 and the expression of p53-responsive genes, such as PUMA and p21, in H1299 cells. 2,5-MeC also activated endogenous p53 and induced apoptosis in U2OS cells. The results suggest that 2,5-MeC is likely to be a promising candidate drug for the clinical treatment of terminal cancer-expressing wild-type p53.

  13. Substituent and ring effects on enthalpies of formation: 2-methyl- and 2-ethylbenzimidazoles versus benzene- and imidazole-derivatives

    NASA Astrophysics Data System (ADS)

    Jiménez, Pilar; Roux, María Victoria; Dávalos, Juan Z.; Temprado, Manuel; Ribeiro da Silva, Manuel A. V.; Ribeiro da Silva, Maria Das Dores M. C.; Amaral, Luísa M. P. F.; Cabildo, Pilar; Claramunt, Rosa M.; Mó, Otilia; Yáñez, Manuel; Elguero, José

    The enthalpies of combustion, heat capacities, enthalpies of sublimation and enthalpies of formation of 2-methylbenzimidazole (2MeBIM) and 2-ethylbenzimidazole (2EtBIM) are reported and the results compared with those of benzimidazole itself (BIM). Theoretical estimates of the enthalpies of formation were obtained through the use of atom equivalent schemes. The necessary energies were obtained in single-point calculations at the B3LYP/6-311+G(d,p) on B3LYP/6-31G* optimized geometries. The comparison of experimental and calculated values of benzenes, imidazoles and benzimidazoles bearing H (unsubstituted), methyl and ethyl groups shows remarkable homogeneity. The energetic group contribution transferability is not followed, but either using it or adding an empirical interaction term, it is possible to generate an enormous collection of reasonably accurate data for different substituted heterocycles (pyrazole-derivatives, pyridine-derivatives, etc.) from the large amount of values available for substituted benzenes and those of the parent (pyrazole, pyridine) heterocycles.

  14. DNA Methylation Dynamics Regulate the Formation of a Regenerative Wound Epithelium during Axolotl Limb Regeneration.

    PubMed

    Aguilar, Cristian; Gardiner, David M

    2015-01-01

    The formation of a blastema during regeneration of an axolotl limb involves important changes in the behavior and function of cells at the site of injury. One of the earliest events is the formation of the wound epithelium and subsequently the apical epidermal cap, which involves in vivo dedifferentiation that is controlled by signaling from the nerve. We have investigated the role of epigenetic modifications to the genome as a possible mechanism for regulating changes in gene expression patterns of keratinocytes of the wound and blastema epithelium that are involved in regeneration. We report a modulation of the expression DNMT3a, a de novo DNA methyltransferase, within the first 72 hours post injury that is dependent on nerve signaling. Treatment of skin wounds on the upper forelimb with decitabine, a DNA methyltransferase inhibitor, induced changes in gene expression and cellular behavior associated with a regenerative response. Furthermore, decitabine-treated wounds were able to participate in regeneration while untreated wounds inhibited a regenerative response. Elucidation of the specific epigenetic modifications that mediate cellular dedifferentiation likely will lead to insights for initiating a regenerative response in organisms that lack this ability. PMID:26308461

  15. Rovibrationally Excited Molecules on the Verge of a Triple Breakdown: Molecular and Roaming Mechanisms in the Photodecomposition of Methyl Formate.

    PubMed

    Lombardi, Andrea; Palazzetti, Federico; Aquilanti, Vincenzo; Li, Hou-Kuan; Tsai, Po-Yu; Kasai, Toshio; Lin, King-Chuen

    2016-07-14

    For the photodissociation of the simplest of esters, methyl formate HCOOCH3, the energy threshold for triple fragmentation into H, CH3O, and CO was measured by previous ion-imaging experiments at a sequence of wavelengths. The translational energy features of product CO in the ground vibrational level (υ = 0) and for selected rotational states were characterized. In this integrated experimental and theoretical approach (i) the focus is at a laser energy barely below that threshold; (ii) Fourier-transform infrared emission spectroscopy measurements probe the rovibrational energy deposition in CO(υ) for υ > 0 and the emergence of the roaming phenomenon; (iii) accompanying quantum chemical calculations describe the selective rupture of bonds; and (iv) molecular dynamics simulations of dissociation are performed, introducing an approach explicitly involving outcomes from paths originated nonadiabatically through conical intersections. Quantitative information on energy disposal is provided: we found extensive vibrational excitation of CO, while rotational bands are colder and bimodal, due to contributions from direct and roaming modes. PMID:26898774

  16. The N-methylated peptide SEN304 powerfully inhibits Aβ(1-42) toxicity by perturbing oligomer formation.

    PubMed

    Amijee, Hozefa; Bate, Clive; Williams, Alun; Virdee, Jasmeet; Jeggo, Ross; Spanswick, David; Scopes, David I C; Treherne, J Mark; Mazzitelli, Sonia; Chawner, Ross; Eyers, Claire E; Doig, Andrew J

    2012-10-23

    Oligomeric forms of β-amyloid (Aβ) have potent neurotoxic activity and are the primary cause of neuronal injury and cell death in Alzheimer's disease (AD). Compounds that perturb oligomer formation or structure may therefore be therapeutic for AD. We previously reported that d-[(chGly)-(Tyr)-(chGly)-(chGly)-(mLeu)]-NH(2) (SEN304) is able to inhibit Aβ aggregation and toxicity, shown primarily by thioflavin T fluorescence and MTT (Kokkoni, N. et al. (2006) N-Methylated peptide inhibitors of β-amyloid aggregation and toxicity. Optimisation of inhibitor structure. Biochemistry 45, 9906-9918). Here we extensively characterize how SEN304 affects Aβ(1-42) aggregation and toxicity, using biophysical assays (thioflavin T, circular dichroism, SDS-PAGE, size exclusion chromatography, surface plasmon resonance, traveling wave ion mobility mass spectrometry, electron microscopy, ELISA), toxicity assays in cell culture (MTT and lactate dehydrogenase in human SH-SHY5Y cells, mouse neuronal cell death and synaptophysin) and long-term potentiation in a rat hippocampal brain slice. These data, with dose response curves, show that SEN304 is a powerful inhibitor of Aβ(1-42) toxicity, particularly effective at preventing Aβ inhibition of long-term potentiation. It can bind directly to Aβ(1-42), delay β-sheet formation and promote aggregation of toxic oligomers into a nontoxic form, with a different morphology that cannot bind thioflavin T. SEN304 appears to work by inducing aggregation, and hence removal, of Aβ oligomers. It is therefore a promising lead compound for Alzheimer's disease. PMID:23025847

  17. OxyR-dependent formation of DNA methylation patterns in OpvABOFF and OpvABON cell lineages of Salmonella enterica

    PubMed Central

    Cota, Ignacio; Bunk, Boyke; Spröer, Cathrin; Overmann, Jörg; König, Christoph; Casadesús, Josep

    2016-01-01

    Phase variation of the Salmonella enterica opvAB operon generates a bacterial lineage with standard lipopolysaccharide structure (OpvABOFF) and a lineage with shorter O-antigen chains (OpvABON). Regulation of OpvAB lineage formation is transcriptional, and is controlled by the LysR-type factor OxyR and by DNA adenine methylation. The opvAB regulatory region contains four sites for OxyR binding (OBSA-D), and four methylatable GATC motifs (GATC1–4). OpvABOFF and OpvABON cell lineages display opposite DNA methylation patterns in the opvAB regulatory region: (i) in the OpvABOFF state, GATC1 and GATC3 are non-methylated, whereas GATC2 and GATC4 are methylated; (ii) in the OpvABON state, GATC2 and GATC4 are non-methylated, whereas GATC1 and GATC3 are methylated. We provide evidence that such DNA methylation patterns are generated by OxyR binding. The higher stability of the OpvABOFF lineage may be caused by binding of OxyR to sites that are identical to the consensus (OBSA and OBSc), while the sites bound by OxyR in OpvABON cells (OBSB and OBSD) are not. In support of this view, amelioration of either OBSB or OBSD locks the system in the ON state. We also show that the GATC-binding protein SeqA and the nucleoid protein HU are ancillary factors in opvAB control. PMID:26687718

  18. DIPPR Project 871 For 1995 - Thermodynamic Properties and Ideal-Gas Enthalpies of Formation for Methyl Benzoate, Ethyl Benzoate, (R)-(+)-Limonene, Tert-Amyl Methyl Ether, Trans-Crotonaldehyde, and

    SciTech Connect

    Steele, W.V.

    2002-07-01

    Ideal-gas enthalpies of formation of methyl benzoate, ethyl benzoate, (R)-(+)-limonene, tert-amyl methyl ether, trans-crotonaldehyde, and diethylene glycol are reported. The standard energy of combustion and hence standard enthalpy of formation of each compound in the liquid phase has been measured using an oxygen rotating-bomb calorimeter without rotation. Vapor pressures were measured to a pressure limit of 270 kPa or the lower decomposition point for each of the six compounds using a twin ebulliometric apparatus. Liquid-phase densities along the saturation line were measured for each compound over a range of temperature (ambient to a maximum of 548 K). A differential scanning calorimeter was used to measure two-phase (liquid + vapor) heat capacities for each compound in the temperature region ambient to the critical temperature or lower decomposition point. For methyl benzoate and tert-amyl methyl ether, critical temperatures and critical densities were determined from the DSC results and corresponding critical pressures derived from the fitting procedures. Fitting procedures were used to derive critical temperatures, critical pressures, and critical densities for each of the remaining compounds. The results of the measurements were combined to derive a series of thermophysical properties including critical temperature, critical density, critical pressure, acentric factor, enthalpies of vaporization (restricted to within {+-}50 K of the temperature region of the experimentally determined vapor pressures), and heat capacities along the saturation line. Wagner-type vapor-pressure equations were derived for each compound. All measured and derived values were compared with those obtained in a search of the literature. Recommended critical parameters are listed for each of the compounds studied. Group-additivity parameters, useful in the application of the Benson gas-phase group-contribution correlations, were derived.

  19. 4,6-O-[1-Cyano-2-(2-iodophenyl)ethylidene] Acetals. Improved Second Generation Acetals for the Stereoselective Formation of β-d-Mannopyranosides and Regioselective Reductive Radical Fragmentation to β-d-Rhamnopyranosides. Scope and Limitations

    PubMed Central

    Crich, David; Bowers, Albert A.

    2015-01-01

    The [1-cyano-2-(2-iodophenyl)]ethylidene group is introduced as an acetal protecting group for carbohydrate thioglycoside donors. The group is easily introduced under mild conditions, over short reaction times, and in presence of a wide variety of other protecting groups by the reaction of the 4,6-diol with triethyl (2-iodophenyl)orthoacetate and trimethylsilyl triflate, followed by trimethylsilyl cyanide and boron trifluoride etherate. The new protecting group conveys strong β-selectivity with thiomannoside donors and undergoes a tin mediated radical fragmentation to provide high yields of the synthetically challenging β-rhamnopyranosides. The method is also applicable to the glucopyranosides when high α-selectivity is observed in the coupling reaction and α-quinovosides are formed selectively in the radical fragmentation step. In the galactopyranoside series, α-glycosides are formed selectively on coupling to donors protected by the new system, but the radical fragmentation is unselective and gives mixtures of the 4- and 6-deoxy products. Variable temperature NMR studies for the glycosylation step, which helped define an optimal protocol, are described. PMID:16626126

  20. 4,6-O-[1-cyano-2-(2-iodophenyl)ethylidene] acetals. improved second-generation acetals for the stereoselective formation of beta-D-mannopyranosides and regioselective reductive radical fragmentation to beta-D-rhamnopyranosides. scope and limitations.

    PubMed

    Crich, David; Bowers, Albert A

    2006-04-28

    The [1-cyano-2-(2-iodophenyl)]ethylidene group is introduced as an acetal-protecting group for carbohydrate thioglycoside donors. The group is easily introduced under mild conditions, over short reaction times, and in the presence of a wide variety of other protecting groups by the reaction of the 4,6-diol with triethyl (2-iodophenyl)orthoacetate and camphorsulfonic acid, followed by trimethylsilyl cyanide and boron trifluoride etherate. The new protecting group conveys strong beta-selectivity with thiomannoside donors and undergoes a tin-mediated radical fragmentation to provide high yields of the synthetically challenging beta-rhamnopyranosides. The method is also applicable to the glucopyranosides when high alpha-selectivity is observed in the coupling reaction and alpha-quinovosides are formed selectively in the radical fragmentation step. In the galactopyranoside series, beta-glycosides are formed selectively on coupling to donors protected by the new system, but the radical fragmentation is unselective and gives mixtures of the 4- and 6-deoxy products. Variable-temperature NMR studies for the glycosylation step, which helped define an optimal protocol, are described. PMID:16626126

  1. Competition between acetate and oleate for the formation of malonyl-CoA and mitochondrial acetyl-CoA in the perfused rat heart

    PubMed Central

    Bian, Fang; Kasumov, Takhar; Jobbins, Kathryn A.; Minkler, Paul E.; Anderson, Vernon E.; Kerner, Janos; Hoppel, Charles L.; Brunengraber, Henri

    2007-01-01

    We previously showed that in the perfused rat heart, the capacity of n-fatty acids to generate mitochondrial acetyl-CoA decreases as their chain length increases. In the present study, we investigated whether the oxidation of a long-chain fatty acid, oleate, is inhibited by short-chain fatty acids, acetate or propionate (which do and do not generate mitochondrial acetyl-CoA, respectively). We perfused rat hearts with buffer containing 4 mM glucose, 0.2 mM pyruvate, 1 mM lactate, and various concentrations of either (i) [U-13C]acetate, (ii) [U-13C]acetate plus [1-13C]oleate, or (iii) unlabeled propionate plus [1-13C]oleate. Using mass isotopomer analysis, we determined the contributions of the labeled substrates to the acetyl moiety of citrate (a probe of mitochondrial acetyl-CoA) and to malonyl-CoA. We found that acetate, even at low concentration, markedly inhibits the oxidation of [1-13C]oleate in the heart, without change in malonyl-CoA concentration. We also found that propionate, at a concentration higher than 1 mM, decreases (i) the contribution of [1-13C]oleate to mitochondrial acetyl-CoA, and (ii) malonyl-CoA concentration. The inhibition by acetate or propionate of acetyl-CoA production from oleate probably results from a competition for mitochondrial CoA between the CoA-utilizing enzymes. PMID:17020764

  2. {sup 13}C-METHYL FORMATE: OBSERVATIONS OF A SAMPLE OF HIGH-MASS STAR-FORMING REGIONS INCLUDING ORION-KL AND SPECTROSCOPIC CHARACTERIZATION

    SciTech Connect

    Favre, Cécile; Bergin, Edwin A.; Crockett, Nathan R.; Neill, Justin L.; Carvajal, Miguel; Field, David; Jørgensen, Jes K.; Bisschop, Suzanne E.; Brouillet, Nathalie; Despois, Didier; Baudry, Alain; Kleiner, Isabelle; Margulès, Laurent; Huet, Thérèse R.; Demaison, Jean E-mail: miguel.carvajal@dfa.uhu.es

    2015-01-01

    We have surveyed a sample of massive star-forming regions located over a range of distances from the Galactic center for methyl formate, HCOOCH{sub 3}, and its isotopologues H{sup 13}COOCH{sub 3} and HCOO{sup 13}CH{sub 3}. The observations were carried out with the APEX telescope in the frequency range 283.4-287.4 GHz. Based on the APEX observations, we report tentative detections of the {sup 13}C-methyl formate isotopologue HCOO{sup 13}CH{sub 3} toward the following four massive star-forming regions: Sgr B2(N-LMH), NGC 6334 IRS 1, W51 e2, and G19.61-0.23. In addition, we have used the 1 mm ALMA science verification observations of Orion-KL and confirm the detection of the {sup 13}C-methyl formate species in Orion-KL and image its spatial distribution. Our analysis shows that the {sup 12}C/{sup 13}C isotope ratio in methyl formate toward the Orion-KL Compact Ridge and Hot Core-SW components (68.4 ± 10.1 and 71.4 ± 7.8, respectively) are, for both the {sup 13}C-methyl formate isotopologues, commensurate with the average {sup 12}C/{sup 13}C ratio of CO derived toward Orion-KL. Likewise, regarding the other sources, our results are consistent with the {sup 12}C/{sup 13}C in CO. We also report the spectroscopic characterization, which includes a complete partition function, of the complex H{sup 13}COOCH{sub 3} and HCOO{sup 13}CH{sub 3} species. New spectroscopic data for both isotopomers H{sup 13}COOCH{sub 3} and HCOO{sup 13}CH{sub 3}, presented in this study, have made it possible to measure this fundamentally important isotope ratio in a large organic molecule for the first time.

  3. Plasmonic-based colorimetric and spectroscopic discrimination of acetic and butyric acids produced by different types of Escherichia coli through the different assembly structures formation of gold nanoparticles.

    PubMed

    La, Ju A; Lim, Sora; Park, Hyo Jeong; Heo, Min-Ji; Sang, Byoung-In; Oh, Min-Kyu; Cho, Eun Chul

    2016-08-24

    We present a plasmonic-based strategy for the colourimetric and spectroscopic differentiation of various organic acids produced by bacteria. The strategy is based on our discovery that particular concentrations of dl-lactic, acetic, and butyric acids induce different assembly structures, colours, and optical spectra of gold nanoparticles. We selected wild-type (K-12 W3110) and genetically-engineered (JHL61) Escherichia coli (E. coli) that are known to primarily produce acetic and butyric acid, respectively. Different assembly structures and optical properties of gold nanoparticles were observed when different organic acids, obtained after the removal of acid-producing bacteria, were mixed with gold nanoparticles. Moreover, at moderate cell concentrations of K-12 W3110 E. coli, which produce sufficient amounts of acetic acid to induce the assembly of gold nanoparticles, a direct estimate of the number of bacteria was possible based on time-course colour change observations of gold nanoparticle aqueous suspensions. The plasmonic-based colourimetric and spectroscopic methods described here may enable onsite testing for the identification of organic acids produced by bacteria and the estimation of bacterial numbers, which have applications in health and environmental sciences. PMID:27497013

  4. Thermochemical characteristics of cellulose acetates with different degrees of acetylation

    NASA Astrophysics Data System (ADS)

    Larina, V. N.; Ur'yash, V. F.; Kushch, D. S.

    2012-12-01

    The standard enthalpies of combustion and formation of cellulose acetates with different degrees of acetylation are determined. It is established that there is a proportional dependence of these thermochemical characteristics vs. the degree of acetylation, weight fraction of bonded acetic acid, and molar mass of the repeating unit of cellulose acetates.

  5. Heats of formation of diphosphene, phosphinophosphinidene, diphosphine, and their methyl derivatives, and mechanism of the borane-assisted hydrogen release.

    PubMed

    Matus, Myrna H; Nguyen, Minh Tho; Dixon, David A

    2007-03-01

    The heats of formation of diphosphene (cis- and trans-P2H2), phopshinophosphinidene (singlet and triplet H2PP) and diphosphine (P2H4), as well as those of the P2H and P2H3 radicals resulting from PH bond cleavages, have been calculated by using high-level ab initio electronic structure theory. Energies were calculated using coupled-cluster theory with a perturbative treatment for triple excitations (CCSD(T)) and employing augmented correlation consistent basis sets with additional tight d-functions on P (aug-cc-pV(n+d)Z) up to quadruple- or quintuple-zeta, to perform a complete basis set extrapolation for the energy. Geometries and vibrational frequencies were determined with the CCSD(T) method. Core-valence and scalar relativistic corrections were included, as well as scaled zero-point energies. We find the following heats of formation (kcal/mol) at 298 [0] K: DeltaH(degree)(f)(P2H) = 53.4 [54.4]; DeltaH(degree)(f)(cis-P2H2) = 32.0 [33.9]; DeltaH(degree)(f)(trans-P2H2) = 28.7 [30.6]; DeltaH(degree)(f)(H2PP) = 53.7 [55.6]; DeltaH(degree)(f)(3H2PP) = 56.5 [58.3]; DeltaH(degree)(f)(P2H3) = 32.3 [34.8]; DeltaH(degree)(f)(P2H4) = 5.7 [9.1] (expt, 5.0 +/- 1.0 at 298 K); and DeltaH(degree)(f)(CH3PH2) = -5.0 [-1.4]. We estimate these values to have an accuracy of +/-1.0 kcal/mol. In contrast to earlier results, we found a singlet ground state for phosphinophosphinidene (H2PP) with a singlet-triplet energy gap of 2.8 kcal/mol. We calculated the heats of formation of the methylated derivatives CH3PPH, CH3HPPH2, CH3PPCH3, CH3HPP, (CH3)2PP, (CH3)2PPH2, and CH3HPPHCH3 by using isodesmic reactions at the MP2/CBS level. The calculated results for the hydrogenation reactions RPPR + H2 --> RHPPHR and R2PP + H2 --> R2PPH2 show that substitution of an organic substituent for H improves the energetics, suggesting that secondary diphosphines and diphosphenes are potential candidates for use in a chemical hydrogen storage system. A comparison with the nitrogen analogues is given. The

  6. Nonintracellular, cell-associated O-methylation of isoproterenol in the isolated rabbit thoracic aorta

    SciTech Connect

    Head, R.J.; Irvine, R.J.; Barone, S.; Stitzel, R.E.; de la Lande, I.S.

    1985-07-01

    The present study examines the subcellular site of catecholamine O-methylation in extraneuronal tissue. S-Adenosyl-l-methionine, a methyl donor that does not diffuse across biological membranes, was used to assess the participation of plasma membrane bound catechol-O-methyltransferase vs. cytoplasmic catechol-O-methyltransferase in the catecholamine O-methylating process. Segments of rabbit thoracic aorta incubated with (methyl-/sup 3/H)-S-adenosyl-l-methionine and isoproterenol generate (/sup 3/H)methoxy-isoproterenol. The formation of (/sup 3/H)methoxy-isoproterenol from (methyl-/sup 3/H)-S-adenosyl-l-methionine was proportional to the isoproterenol concentrations in the range of 0.1 to 1.0 microM. There was a marked preference for the O-methylation of the (+)- rather than the (-)-isomer of isoproterenol. The O-methylation of isoproterenol in the presence of (methyl-/sup 3/H)-S-adenosyl-l-methionine was stimulated as much as 8-fold by the removal of calcium ions from the incubation solutions. In contrast, the O-methylation of (+)-(/sup 3/H)isoproterenol by endogenous, intracellular S-adenosyl-l-methionine was only slightly inhibited by the removal of calcium ions from incubation solutions. The formation of (/sup 3/H)methoxy-isoproterenol from (methyl-/sup 3/H)-S-adenosyl-l-methionine and isoproterenol was not inhibited by pretreatment of tissues with phenoxybenzamine (32 microM) or treatment with metanephrine (27 mumol 1(-1) or deoxycorticosterone acetate (27 microM), i.e., drug treatments that inhibit the extraneuronal uptake and O-methylation of (/sup 3/H)-isoproterenol by endogenous intracellular S-adenosyl-l-methionine. The results of this study provide evidence for a nonintracellular, cell-associated site of O-methylation of isoproterenol in the rabbit aorta.

  7. Separating acetic acid from furol (furfural) by electrodialysis method

    SciTech Connect

    Guan, S.F.; Li, C.S. Ye, S.T.; Shen, S.Y.; Wang, Y.T.; Yu, S.H.

    1981-01-01

    Furfural production by hydrolysis of fibrous plant materials is accompanied by formation of acetic acid in amounts depending on the material used. The amount of acetic formed in the hydrolysis of the fruit shell of oil-tea camellia (Camellia oleosa) (an oilseed-bearing tree) is equal to the amount of furfural. The acetic acid can be separated from the furfural and concentrated to 10% by electrodialysis. A smaller amount of furfural is separated with acetic acid.

  8. 40 CFR 180.551 - Fluthiacet-methyl; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... residues of the herbicide, fluthiacet-methyl, acetic acid thiadiazolo pyridazin-1-ylidene)amino]phenyl]thio...-methyland its acid metabolite: acetic acid, thiadiazolo pyridazin-1-ylidene)amino]phenyl]thio]-methyl ester, and its acid metabolite, acetic acid, thiadiazolo pyridazin-1-ylidene)amino]phenyl]thio]- , in or...

  9. 40 CFR 180.551 - Fluthiacet-methyl; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... residues of the herbicide, fluthiacet-methyl, acetic acid thiadiazolo pyridazin-1-ylidene)amino]phenyl]thio...-methyland its acid metabolite: acetic acid, thiadiazolo pyridazin-1-ylidene)amino]phenyl]thio]-methyl ester, and its acid metabolite, acetic acid, thiadiazolo pyridazin-1-ylidene)amino]phenyl]thio]- , in or...

  10. Organosulfates as Tracers for Secondary Organic Aerosol (SOA) Formation from 2-Methyl-3-Buten-2 ol (MBO) in the Atmosphere

    EPA Science Inventory

    2-Methyl-3-buten-2-ol (MBO) is an important biogenic volatile organic compound (BVOC) emitted by pine trees and a potential precursor of atmospheric secondary organic aerosol (SOA) in forested regions. In the present study, hydroxyl radical (OH)-initiated oxidation of MBO was exa...

  11. 5-hydroxyconiferyl aldehyde modulates enzymatic methylation for syringyl monolignol formation, a new view of monolignol biosynthesis in angiosperms.

    PubMed

    Li, L; Popko, J L; Umezawa, T; Chiang, V L

    2000-03-01

    S-Adenosyl-L-methionine-dependent caffeate O-methyltransferase (COMT, EC 2.1.1.6) has traditionally been thought to catalyze the methylation of caffeate and 5- hydroxyferulate for the biosynthesis of syringyl monolignol, a lignin constituent of angiosperm wood that enables efficient lignin degradation for cellulose production. However, recent recognition that coniferyl aldehyde prevents 5-hydroxyferulate biosynthesis in lignifying tissue, and that the hydroxylated form of coniferyl aldehyde, 5-hydroxyconiferyl aldehyde, is an alternative COMT substrate, demands a re-evaluation of the role of COMT during monolignol biosynthesis. Based on recombinant aspen (Populus tremuloides) COMT enzyme kinetics coupled with mass spectrometry analysis, this study establishes for the first time that COMT is in fact a 5-hydroxyconiferyl aldehyde O-methyltransferase (AldOMT), and that 5-hydroxyconiferyl aldehyde is both the preferred AldOMT substrate and an inhibitor of caffeate and 5-hydroxyferulate methylation, as measured by K(m) and K(i) values. 5-Hydroxyconiferyl aldehyde also inhibited the caffeate and 5-hydroxyferulate methylation activities of xylem proteins from various angiosperm tree species. The evidence that syringyl monolignol biosynthesis is independent of caffeate and 5-hydroxyferulate methylation supports our previous discovery that coniferyl aldehyde prevents ferulate 5-hydroxylation and at the same time ensures a coniferyl aldehyde 5-hydroxylase (CAld5H)-mediated biosynthesis of 5-hydroxyconiferyl aldehyde. Together, our results provide conclusive evidence for the presence of a CAld5H/AldOMT-catalyzed coniferyl aldehyde 5-hydroxylation/methylation pathway that directs syringyl monolignol biosynthesis in angiosperms. PMID:10692459

  12. Formation of molecular complexes of salicylic acid, acetylsalicylic acid, and methyl salicylate in a mixture of supercritical carbon dioxide with a polar cosolvent

    NASA Astrophysics Data System (ADS)

    Petrenko, V. E.; Antipova, M. L.; Gurina, D. L.; Odintsova, E. G.

    2015-08-01

    The solvate structures formed by salicylic acid, acetylsalicylic acid, and methyl salicylate in supercritical (SC) carbon dioxide with a polar cosolvent (methanol, 0.03 mole fractions) at a density of 0.7 g/cm3 and a temperature of 318 K were studied by the molecular dynamics method. Salicylic and acetylsalicylic acids were found to form highly stable hydrogen-bonded complexes with methanol via the hydrogen atom of the carboxyl group. For methyl salicylate in which the carboxyl hydrogen is substituted by a methyl radical, the formation of stable hydrogen bonds with methanol was not revealed. The contribution of other functional groups of the solute to the interactions with the cosolvent was much smaller. An analysis of correlations between the obtained data and the literature data on the cosolvent effect on the solubility of the compounds in SC CO2 showed that the dissolving ability of SC CO2 with respect to a polar organic substance in the presence of a cosolvent increased only when stable hydrogen-bonded complexes are formed between this substance and the cosolvent.

  13. IAA-synthase, an enzyme complex from Arabidopsis thaliana catalyzing the formation of indole-3-acetic acid from (S)-tryptophan.

    PubMed

    Müller, A; Weiler, E W

    2000-08-01

    An enzyme complex was isolated from Arabidopsis thaliana that catalyzes the entire pathway of biosynthesis of the major plant growth hormone, indole-3-acetic acid (IAA), from (S)-tryptophan. The 160-180 kDa, soluble complex catalyzes a strictly O2-dependent reaction which requires no further added factors and is stereospecific for the substrate (S)-tryptophan (app. Km = 120 microM). H2(18)O labeling proved that both oxygen atoms of IAA were delivered via H2O. This, as well as immunological evidence for the presence of a nitrilase-like protein in the complex, suggests the reaction to proceed via the intermediate indole-3-acetonitrile. IAA-synthase forms a tight metabolite channel committed to IAA production and occurs in shoots, roots and cell cultures of A. thaliana. PMID:11030425

  14. 40 CFR 180.554 - Kresoxim-methyl; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... metabolites as follows: (E)-2- -phenyl-2-(methoxyimido)acetic acid; (E)-2- -phenyl-2-(methoxyimido)acetic acid (free and glucose conjugated); and (E)-2- phenyl-2-(methoxyimido)acetic acid (free and glucose...- -phenyl-2-(methoxyimido)acetic acid resulting from the use of the fungicide kresoxim-methyl:...

  15. Crystal structure of ethyl 2-{4-[(5-chloro-1-benzo-furan-2-yl)meth-yl]-3-methyl-6-oxo-1,6-di-hydro-pyridazin-1-yl}acetate.

    PubMed

    Boukharsa, Youness; El Ammari, Lahcen; Taoufik, Jamal; Saadi, Mohamed; Ansar, M'hammed

    2015-05-01

    In the title compound, C18H17ClN2O4, the dihedral angle between the benzofuran ring system [maximum deviation 0.014 (2) Å] and the oxopyradizine ring is 73.33 (8)°. The structure is characterized by disorder of the ethyl group, which is split into two parts, with a major component of 0.57 (3), and the acetate carbonyl O atom, which is statistically disordered. In the crystal, the molecules are linked by C-H⋯O inter-actions, forming a three-dimensional network. PMID:25995910

  16. Formation of 6-methyl-1,4-dihydronaphthalene in the reaction of the p-tolyl radical with 1,3-butadiene under single-collision conditions.

    PubMed

    Parker, Dorian S N; Dangi, Beni B; Kaiser, Ralf I; Jamal, Adeel; Ryazantsev, Mikhail; Morokuma, Keiji

    2014-12-26

    Crossed molecular beam reactions of p-tolyl (C7H7) plus 1,3-butadiene (C4H6), p-tolyl (C7H7) plus 1,3-butadiene-d6 (C4D6), and p-tolyl-d7 (C7D7) plus 1,3-butadiene (C4H6) were carried out under single-collision conditions at collision energies of about 55 kJ mol(-1). 6-Methyl-1,4-dihydronaphthalene was identified as the major reaction product formed at fractions of about 94% with the monocyclic isomer (trans-1-p-tolyl-1,3-butadiene) contributing only about 6%. The reaction is initiated by barrierless addition of the p-tolyl radical to the terminal carbon atom of the 1,3-butadiene via a van der Waals complex. The collision complex isomerizes via cyclization to a bicyclic intermediate, which then ejects a hydrogen atom from the bridging carbon to form 6-methyl-1,4-dihydronaphthalene through a tight exit transition state located about 27 kJ mol(-1) above the separated products. This is the dominant channel under the present experimental conditions. Alternatively, the collision complex can also undergo hydrogen ejection to form trans-1-p-tolyl-1,3-butadiene; this is a minor contributor to the present experiment. The de facto barrierless formation of a methyl-substituted aromatic hydrocarbons by dehydrogenation via a single event represents an important step in the formation of polycyclic aromatic hydrocarbons (PAHs) and their partially hydrogenated analogues in combustion flames and the interstellar medium. PMID:25407848

  17. Vacuum-UV irradiation-based formation of methyl-Si-O-Si networks from poly(1,1-dimethylsilazane-co-1-methylsilazane).

    PubMed

    Prager, Lutz; Wennrich, Luise; Heller, Roswitha; Knolle, Wolfgang; Naumov, Sergej; Prager, Andrea; Decker, Daniel; Liebe, Hubert; Buchmeiser, Michael R

    2009-01-01

    The vacuum-UV (VUV)-induced conversion of commercially available poly(1,1-dimethylsilazane-co-1-methylsilazane) into methyl-Si-O-Si networks was studied using UV sources at wavelengths around 172, 185, and 222 nm, respectively. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS), X-ray photo electron spectroscopy (XPS), and Fourier transform infrared (FTIR) measurements, as well as kinetic investigations, were carried out to elucidate the degradation process. First-order kinetics were found for the photolytically induced decomposition of the Si-NH-Si network, the subsequent formation of the methyl-Si-O-Si network and the concomitant degradation of the Si-CH(3) bond, which were additionally independent of the photon energy above a threshold of about 5.5 eV (225 nm). The kinetics of these processes were, however, dependent on the dose actually absorbed by the layer and, in the case of Si-O-Si formation, additionally on the oxygen concentration. The release of ammonia and methane accompanied the conversion process. Quantum-chemical calculations on methyl substituted cyclotetrasilazanes as model compounds substantiate the suggested reaction scheme. Layers <100 nm in thickness based on mixtures of poly(1,1-dimethylsilazane-co-1-methylsilazane) and perhydropolysilazane (PHPS) were coated onto polyethylene terephthalate (PET) foils by a continuous roll to roll process and cured by VUV irradiation by using wavelengths <200 nm and investigated for their O(2) and water vapor-barrier properties. It was found that the resulting layers displayed oxygen and water vapor transmission rates (OTR and WVTR, respectively) of <1 cm(3) m(-2) d(-1) bar(-1) and <4 g m(-2) d(-1), respectively. PMID:19040228

  18. Biosynthesis of vitamin B12: nature of the volatile fragment generated during formation of the corrin ring system.

    PubMed Central

    Mombelli, L; Nussbaumer, C; Weber, H; Müller, G; Arigoni, D

    1981-01-01

    It is shown with the help of radiolabeled substrates that biological formation of the corrin ligand system of cobyrinic acid is linked with the release of an equivalent of acetic acid from a hydroporphinoid precursor in which the C-20 atom has undergone methylation prior to its excision from the macrocycle. PMID:6938989

  19. Preparation of vinyl acetate

    DOEpatents

    Tustin, Gerald Charles; Zoeller, Joseph Robert; Depew, Leslie Sharon

    1998-01-01

    This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

  20. Preparation of vinyl acetate

    DOEpatents

    Tustin, G.C.; Zoeller, J.R.; Depew, L.S.

    1998-03-24

    This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

  1. NML-mediated rRNA base methylation links ribosomal subunit formation to cell proliferation in a p53-dependent manner.

    PubMed

    Waku, Tsuyoshi; Nakajima, Yuka; Yokoyama, Wataru; Nomura, Naoto; Kako, Koichiro; Kobayashi, Akira; Shimizu, Toshiyuki; Fukamizu, Akiyoshi

    2016-06-15

    Ribosomal RNAs (rRNAs) act as scaffolds and ribozymes in ribosomes, and these functions are modulated by post-transcriptional modifications. However, the biological role of base methylation, a well-conserved modification of rRNA, is poorly understood. Here, we demonstrate that a nucleolar factor, nucleomethylin (NML; also known as RRP8), is required for the N(1)-methyladenosine (m(1)A) modification in 28S rRNAs of human and mouse cells. NML also contributes to 60S ribosomal subunit formation. Intriguingly, NML depletion increases 60S ribosomal protein L11 (RPL11) levels in the ribosome-free fraction and protein levels of p53 through an RPL11-MDM2 complex, which activates the p53 pathway. Consequently, the growth of NML-depleted cells is suppressed in a p53-dependent manner. These observations reveal a new biological function of rRNA base methylation, which links ribosomal subunit formation to p53-dependent inhibition of cell proliferation in mammalian cells. PMID:27149924

  2. Effect of sugarcane molasses extract on the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in a model system.

    PubMed

    Yu, Di; Chen, Ming-Shun; Yu, Shu-Juan

    2016-04-15

    Molasses, the main by-product of sugar production, is a well-known source of antioxidants. In this study, sugarcane molasses extract was investigated for its total phenolic content and in vitro antioxidant capacity. The experimental total phenolic content was 101.3 mg of gallic acid equivalent (GAE) in 1 g of extract, IC50 of Trolox and sugarcane molasses extract were 125.33 μg/ml and 126.0 μg/ml, respectively. A chemical model system showed that the sugarcane molasses extract effectively reduced the formation of phenylacetaldehyde and the aldol condensation product, meanwhile, the amount of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) also decreased. This could be due to the reaction between the phenolic compounds of sugarcane molasses extract and the carbonyl group of phenylacetaldehyde inhibiting the aldol condensation product formation, and this would suppress the formation of PhIP. A pathway that phenolic compounds inhibited the formation of PhIP is proposed. This pathway also suggested a mechanism for how the sugarcane affects the formation of PHIP. PMID:26617035

  3. Relationship between Indole-3-Acetic Acid Levels in Apple (Malus pumila Mill) Rootstocks Cultured in Vitro and Adventitious Root Formation in the Presence of Indole-3-Butyric Acid.

    PubMed

    Alvarez, R; Nissen, S J; Sutter, E G

    1989-02-01

    In vitro rooting response and indole-3-acetic acid (IAA) levels were examined in two genetically related dwarfing apple (Malus pumila Mill) rootstocks. M.26 and M.9 were cultured in vitro using Linsmaier-Skoog medium supplemented with benzyladenine (BA), indole-3-butyric acid (IBA), and 1,3,5-trihydroxybenzoic acid (PG). Rooting response was tested in Lepoivre medium supplemented with IBA and PG. IBA concentrations of 12.0 and 4.0 micromolar induced the maximum rooting percentages for M.9 and M.26, respectively. At these concentrations rooting response was 100% for M.26 and 80% for M.9. Free and conjugated IAA levels were determined in M.26 and M.9 shoots prior to root inducing treatment by high performance liquid chromatography with fluorescence detection and validated by gas chromatography-mass spectrometry using (13)[C(6)]IAA as internal standard. Basal sections of M.26 shoots contained 2.8 times more free IAA than similar tissue in M.9 (477.1 +/- 6.5 versus 166.6 +/- 6.7 nanograms per gram fresh weight), while free IAA levels in apical sections of M.26 and M.9 shoots were comparable (298.0 +/- 4.4 versus 263.7 +/- 9.3 nanograms per gram fresh weight). Conjugated IAA levels were significantly higher in M.9 than in M.26 indicating that a greater proportion of total IAA was present as a conjugate in M.9. These data suggest that differences between M.26 and M.9 rooting responses may be related to differences in free IAA levels in the shoot base. PMID:16666562

  4. Acetate Causes Alcohol Hangover Headache in Rats

    PubMed Central

    Maxwell, Christina R.; Spangenberg, Rebecca Jay; Hoek, Jan B.; Silberstein, Stephen D.; Oshinsky, Michael L.

    2010-01-01

    Background The mechanism of veisalgia cephalgia or hangover headache is unknown. Despite a lack of mechanistic studies, there are a number of theories positing congeners, dehydration, or the ethanol metabolite acetaldehyde as causes of hangover headache. Methods We used a chronic headache model to examine how pure ethanol produces increased sensitivity for nociceptive behaviors in normally hydrated rats. Results Ethanol initially decreased sensitivity to mechanical stimuli on the face (analgesia), followed 4 to 6 hours later by inflammatory pain. Inhibiting alcohol dehydrogenase extended the analgesia whereas inhibiting aldehyde dehydrogenase decreased analgesia. Neither treatment had nociceptive effects. Direct administration of acetate increased nociceptive behaviors suggesting that acetate, not acetaldehyde, accumulation results in hangover-like hypersensitivity in our model. Since adenosine accumulation is a result of acetate formation, we administered an adenosine antagonist that blocked hypersensitivity. Discussion Our study shows that acetate contributes to hangover headache. These findings provide insight into the mechanism of hangover headache and the mechanism of headache induction. PMID:21209842

  5. In vitro anticancer activity of methyl caffeate isolated from Solanum torvum Swartz. fruit.

    PubMed

    Balachandran, C; Emi, N; Arun, Y; Yamamoto, Y; Ahilan, B; Sangeetha, B; Duraipandiyan, V; Inaguma, Yoko; Okamoto, Akinao; Ignacimuthu, S; Al-Dhabi, N A; Perumal, P T

    2015-12-01

    The present study was undertaken to investigate the anticancer activity of methyl caffeate isolated from Solanum torvum Swartz. fruit and to explore the molecular mechanisms of action in MCF-7 cells. Cytotoxic properties of hexane, ethyl acetate and methanol extracts were carried out against MCF-7 cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Ethyl acetate extract showed good cytototoxic activities compared to hexane and methanol extracts. Methyl caffeate was isolated from the ethyl acetate extract using column chromatography. Cytotoxic properties of methyl caffeate was investigated against MCF-7, A549, COLO320, HepG-2 and Vero cells. The compound showed potent cytotoxic properties against MCF-7 cells compared to A549, COLO320 and HepG-2 cells. Methyl caffeate significantly reduced cell proliferation and increased formation of fragmented DNA and apoptotic body in MCF-7 cells. Bcl-2, Bax, Bid, p53, caspase-3, PARP and cytochrome c release were detected by western blot analysis. The activities of caspases-3 and PARP gradually increased after the addition of isolated compound. Bcl-2 protein was down regulated; Bid and Bax were up regulated after the treatment with methyl caffeate. Molecular docking studies showed that the compound bound stably to the active sites of poly (ADP-ribose) polymerase-1 (PARP1), B cell CLL/lymphoma-2 (BCL-2), E3 ubiquitin-protein ligase (MDM2) and tubulin. The results strongly suggested that methyl caffeate induced apoptosis in MCF-7 cells via caspase activation through cytochrome c release from mitochondria. PMID:26415618

  6. Fate of methyl methacrylate in rats.

    PubMed Central

    Bratt, H.; Hathway, D. E.

    1977-01-01

    Up to 88% of a single dose of methyl[14C]methacrylate in rats is expired as 14CO2 in 10 days (65% in 2 h), irrespective of the route of administration and of the specific labelling of the propylene residue of the molecule. The implications of this observation, and of the excretion of small amounts of [14C]methylmalonate, [14C]-succinate and probably of [14C]beta-hydroxyisobutyrate and 2-formylpropionate, and of the formation of [14C] normal, physiological metabolites that may be accounted for by anabolism both from 14CO2 and from [14C]acetate emergent from the citric acid cycle, are that the metabolic pathway concerned involves intermediary metabolism and relates to mitochondrial function. Present findings are discussed in relation to the imputations of a report of carcinogenic risk. PMID:889678

  7. Impacts of aqueous phase radical mechanism of oligomerization of methyl vinyl ketone (MVK) on SOA formation: on the prevailing role of dissolved oxygen

    NASA Astrophysics Data System (ADS)

    Renard, P.; Ervens, B.; Siekmann, F.; Vassalo, L.; Ravier, S.; Clement, J.; Monod, A.

    2012-12-01

    It is now recognized that the aqueous phase photochemistry of organic compounds in cloud droplets and deliquescent aerosol particles lead to the formation of oligomers and thus it might produce a substantial amount of atmospheric Secondary Organic Aerosol (SOA) with unique properties. However, the chemical mechanisms leading to these oligomers are still poorly understood, and consequently, their atmospheric impacts are difficult to assess. The goal of this study was to investigate the atmospheric impact of an aqueous phase radical mechanism of oligomerization of methyl vinyl ketone (MVK: one of the main reaction products of isoprene) on SOA formation. Aqueous phase photooxidation of MVK was investigated in a photoreactor using photolysis of H2O2 as OH radical generator. Electrospray high resolution mass spectrometry analysis of the solutions brought clear evidence for the formation of oligomer systems having a mass range of up to 1800 Da within less than 15 minutes of reaction. Highest oligomer formation rates were obtained under conditions of low dissolved oxygen, highest temperature and highest MVK initial concentrations. A radical mechanism of polymerization is proposed to explain this oligomer formation. Furthermore, we quantified the total amount of carbon present in oligomers, and the initial radical branching ratios. Kinetic parameters of the proposed oligomerization mechanism are constrained by means of a box model that is able to reproduce the temporal evolution of intermediates and products as observed in the laboratory experiments. Additional model simulations for atmospherically-relevant conditions will be presented that show the extent to which these radical processes contribute to SOA formation in the multiphase system as compared to other aqueous phase as well as traditional SOA sources.

  8. Intramolecular electron density redistribution upon hydrogen bond formation in the anion methyl orange at the water/1,2-dichloroethane interface probed by phase interference second harmonic generation

    PubMed

    Rinuy; Piron; Brevet; Blanchard-Desce; Girault

    2000-09-15

    Surface second harmonic generation (SSHG) studies of the azobenzene derivative p-dimethylaminoazobenzene sulfonate, often referred as Methyl Orange (MO), at the neat water/1,2-dichloroethane (DCE) interface is reported. The two forms of the anionic MO dye, which are usually observed in bulk solution, with one form being hydrogen bonded to a water molecule through the azo nitrogens (MO/H2O) and the other form not being hydrogen bonded (MO) have also been observed at the water/DCE interface. Their equilibrium constant has been compared with the corresponding bulk solution and found to be identical. The adsorption equilibrium of the two forms has been determined and the Gibbs energy of adsorption measured to be -30 kJmol(-1) for both forms. From a light polarisation analysis of the SH signal, the angle of orientation of the MO transition dipole moment was found to be 34 +/- 2 degrees for MO and 43 +/- 2 degrees for MO/H2O under the assumption of a Dirac delta function for the angle distribution, a difference explained by the different solvation properties of the two forms. Furthermore, the wavelength dependence analysis of these data revealed an interference pattern resulting from the electronic density redistribution within the hydrated anionic form occurring upon the formation of the hydrogen bond with a water molecule. This interference pattern was clearly evidenced with the use of another dye at the interface in order to define a phase reference to both forms of Methyl Orange. PMID:11039537

  9. The histone H3K9 methylation and RNAi pathways regulate normalnucleolar and repeated DNA organization by inhibiting formation ofextrachromosomal DNAs

    SciTech Connect

    Peng, Jamy C.; Karpen, Gary H.

    2006-06-15

    In order to identify regulators of nuclear organization, Drosophila mutants in the Su(var)3-9 histone H3K9 methyltransferase, RNAi pathway components, and other regulators of heterochromatin-mediated gene silencing were examined for altered nucleoli and positioning of repeated DNAs. Animals lacking components of the H3K9 methylation and RNAi pathways contained disorganized nucleoli, ribosomal DNA (rDNA) and satellite DNAs. The levels of H3K9 dimethylation (H3K9me2) in chromatin associated with repeated DNAs decreased dramatically in Su(var)3-9 and dcr-2 (dicer-2) mutant tissues compared to wild type. We also observed a substantial increase in extrachromosomal repeated DNAs in mutant tissues. The disorganized nucleolus phenotype depends on the presence of Ligase 4 (Lig4), and ecc DNA formation is not induced by removal of cohesin. We conclude that H3K9 methylation of rDNA and satellites, maintained by Su(var)3-9, HP1, and the RNAi pathway, is necessary for the structural stability of repeated DNAs, which is mediated through suppression of non-homologous end joining (NHEJ). These results suggest a mechanism for how local chromatin structure can regulate genome stability, and the organization of chromosomal elements and nuclear organelles.

  10. The kinetics of complex formation in the trithiadiazoletri[3,4-di(4- tert-butylphenyl)-pyrrole] macrocycle-copper(II) acetate-DMFA-H2O system

    NASA Astrophysics Data System (ADS)

    Lomova, T. N.; Mozhzhukhina, E. G.; Danilova, E. A.; Islyaikin, M. K.

    2009-10-01

    The paper presents the results of a study of the kinetics of coordination of a macroheterocyclic compound with an increased coordination cavity of the (3 + 3) McH3 composition consisting of sequentially alternating 1,3,4-thiadiazole and 3,4-bis(4- tert-butylphenyl)pyrrole fragments to dehydrated Cu(OAc)2 in dimethylformamide with and without H2O admixtures. The reaction could be controlled spectrophotometrically over the salt and ligand concentration ranges (0.175-0.55) × 10-4 and (0.16-0.64) × 10-5 mol/l, respectively, at temperatures of 288-303 K. A kinetic equation of an unusual form with a negative order with respect to the salt was for the first time obtained experimentally for a macrocyclic ligand by the method of excess concentrations. The kinetics of the complex formation reaction was given a theoretical interpretation. Quantitative characteristics were obtained, and the role played by water in the kinetics of complex formation was studied. These data were of importance for practical applications, for the development of optimum conditions increasing the yield of complexes when they were synthesized in complex formation reactions.

  11. 'Remote' adiabatic photoinduced deprotonation and aggregate formation of amphiphilic N-alkyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride salts.

    PubMed

    Abraham, Shibu; Weiss, Richard G

    2011-11-30

    The absorption and emission properties of a series of amphiphilic N-alkyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride salts were investigated in solvents of different polarities and over a wide concentration range. For example, at 10(-5) M concentrations in tetrahydrofuran (THF), salts with at least one N-H bond exhibited broad, structureless emissions even though time-correlated single photon counting (TCSPC) experiments indicated negligible static or dynamic intermolecular interactions. Salts with a butylene spacer or lacking an N-H bond showed no discernible structureless emission; their emission spectra were dominated by the normal monomeric fluorescence of a pyrenyl group and the TCSPC histograms could be interpreted on the basis of intramolecular photophysics. The broad, structureless emission is attributed to an unprecedented, rapid, adiabatic proton-transfer to the medium, followed by the formation of an intramolecular exciplex consisting of amine and pyrenyl groups. The proposed mechanism involves excitation of a ground-state conformer of the salts in which the ammonium group sits over the pyrenyl ring due to electrostatic stabilization. At higher concentrations, with longer N-alkyl groups, or in selected solvents, electronic excitation of the salts led to dynamic and static excimeric emissions. For example, whereas the emission spectrum of 10(-3) M N-hexyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride in THF consisted of comparable amounts of monomeric and excimeric emission, the emission from 10(-5) M N-dodecyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride in 1:9 (v:v) ethanol/water solutions was dominated by excimeric emission, and discrete particles near micrometer size were discernible from confocal microscopy and dynamic light scattering experiments. Comparison of the static and dynamic emission characteristics of the particles and of the neat solid of N-dodecyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride indicate that molecular

  12. Stable carbon isotope discrimination in rice field soil during acetate turnover by syntrophic acetate oxidation or acetoclastic methanogenesis

    NASA Astrophysics Data System (ADS)

    Conrad, Ralf; Klose, Melanie

    2011-03-01

    Rice fields are an important source for the greenhouse gas methane. In Italian rice field soil CH 4 is produced either by hydrogenotrophic and acetoclastic methanogenesis, or by hydrogenotrophic methanogenesis and syntrophic acetate oxidation when temperatures are below and above about 40-45 °C, respectively. In order to see whether these acetate consumption pathways differently discriminate the stable carbon isotopes of acetate, we measured the δ 13C of total acetate and acetate-methyl as well as the δ 13C of CO 2 and CH 4 in rice field soil that had been pre-incubated at 45 °C and then shifted to different temperatures between 25 and 50 °C. Acetate transiently accumulated to about 6 mM, which is about one-third of the amount of CH 4 produced, irrespective of the incubation temperature and the CH 4 production pathway involved. However, the patterns of δ 13C of the CH 4 and CO 2 produced were different at low (25, 30, 35 °C) versus high (40, 45, 50 °C) temperatures. These patterns were consistent with CH 4 being exclusively formed by hydrogenotrophic methanogenesis at high temperatures, and by a combination of acetoclastic and hydrogenotrophic methanogenesis at low temperatures. The patterns of δ 13C of total acetate and acetate-methyl were also different at high versus low temperatures, indicating the involvement of different pathways of production and consumption of acetate at the two temperature regimes. Isotope fractionation during consumption of the methyl group of acetate was more pronounced at low ( α = 1.010-1.025) than at high ( α = 1.0-1.01) temperatures indicating that acetoclastic methanogenesis exhibits a stronger isotope effect than syntrophic acetate oxidation. Small amounts of propionate also transiently accumulated and were analyzed for δ 13C. The δ 13C values slightly increased (by about 10‰) during production and consumption of propionate, but were not affected by incubation temperature. Collectively, our results showed distinct

  13. Micelles Protect and Concentrate Activated Acetic Acid

    NASA Astrophysics Data System (ADS)

    Todd, Zoe; House, C.

    2014-01-01

    As more and more exoplanets are discovered and the habitability of such planets is considered, one can turn to searching for the origin of life on Earth in order to better understand what makes a habitable planet. Activated acetic acid, or methyl thioacetate, has been proposed to be central to the origin of life on Earth, and also as an important energy currency molecule in early cellular evolution. We have investigated the hydrolysis of methyl thioacetate under various conditions. Its uncatalyzed rate of hydrolysis is about three orders of magnitude faster (K = 0.00663 s^-1; 100°C, pH 7.5, concentration = 0.33mM) than published rates for its catalyzed production making it unlikely to accumulate under prebiotic conditions. However, we also observed that methyl thioacetate was protected from hydrolysis when inside its own hydrophobic droplets. We found that methyl thioacetate protection from hydrolysis was also possible in droplets of hexane and in the membranes of nonanoic acid micelles. Thus, the hydrophobic regions of prebiotic micelles and early cell membranes could have offered a refuge for this energetic molecule increasing its lifetime in close proximity to the reactions for which it would be needed. Methyl thioacetate could thus be important for the origin of life on Earth and perhaps for better understanding the potential habitability of other planets.

  14. Creatine is a scavenger for methylglyoxal under physiological conditions via formation of N-(4-methyl-5-oxo-1-imidazolin-2-yl)sarcosine (MG-HCr).

    PubMed

    Löbner, Jürgen; Degen, Julia; Henle, Thomas

    2015-03-01

    Following incubation of methylglyoxal and creatine under physiological conditions, N-(4-methyl-5-oxo-1-imidazolin-2-yl)sarcosine (MG-HCr) was isolated and identified by NMR and mass spectrometry. Due to its rapid formation, MG-HCr represents a specific product following "scavenging" of methylglyoxal by creatine. Using hydrophilic interaction chromatography coupled to mass spectrometry, MG-HCr was analyzed in urine samples of healthy volunteers. Daily MG-HCr excretion of nonvegetarians ranged from 0.35 to 3.84 μmol/24 h urine (median: 0.90 μmol/24 h urine) and of vegetarians from 0.11 to 0.31 μmol/24 h urine (median: 0.19 μmol/24 h urine), indicating that formation of MG-HCr in vivo is influenced by the dietary intake of creatine. The trapping of methylglyoxal by creatine may delay the formation of advanced glycation compounds in vivo and, therefore, could be of special importance in situations in which the body has to deal with pathophysiologically increased amounts of dicarbonyl compounds ("carbonyl stress"), for instance in diabetic patients. PMID:25655840

  15. Effects of some cations on the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in a model system.

    PubMed

    Yu, Di; Yu, Shu-Juan

    2016-06-15

    The present study aimed to investigate in detail the changes to 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and its precursors in the presence of some cations (i.e., K(+), Na(+), Ca(2+), Mg(2+), Fe(2+) and Fe(3+)) in a creatinine/phenylacetaldehyde model system. Results showed that PhIP yields decreased when Fe(2+)and Fe(3+) were added to a mixture of phenylacetaldehyde and creatinine. This decrease may be attributed to the fact that Fe(3+) can form complexes with various properties with creatinine and accelerate creatinine degradation. This pathway can disturb the reaction with phenylacetaldehyde, influence aldol condensation product formation, and suppress PhIP formation. Furthermore, Ca(2+)and Mg(2+) enhanced PhIP content. Such enhancement may be attributed to the fact that CaCl2 and MgCl2 promote aldol and aldol condensation product reactions with ammonia and formaldehyde. A possible mechanism for the action of cations during PhIP formation in a model system is also proposed. PMID:26868546

  16. C-H activation and C=C double bond formation reactions in iridium ortho-methyl arylphosphane complexes.

    PubMed

    Baratta, Walter; Ballico, Maurizio; Del Zotto, Alessandro; Zangrando, Ennio; Rigo, Pierluigi

    2007-01-01

    The Vaska-type iridium(I) complex [IrCl(CO){PPh(2)(2-MeC(6)H(4))}(2)] (1), characterized by an X-ray diffraction study, was obtained from iridium(III) chloride hydrate and PPh(2)(2,6-MeRC(6)H(3)) with R=H in DMF, whereas for R=Me, activation of two ortho-methyl groups resulted in the biscyclometalated iridium(III) compound [IrCl(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}(2)] (2). Conversely, for R=Me the iridium(I) compound [IrCl(CO){PPh(2)(2,6-Me(2)C(6)H(3))}(2)] (3) can be obtained by treatment of [IrCl(COE)(2)](2) (COE=cyclooctene) with carbon monoxide and the phosphane in acetonitrile. Compound 3 in CH(2)Cl(2) undergoes intramolecular C-H oxidative addition, affording the cyclometalated hydride iridium(III) species [IrHCl(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}{PPh(2)(2,6-Me(2)C(6)H(3))}] (4). Treatment of 2 with Na[BAr(f) (4)] (Ar(f)=3,5-C(6)H(3)(CF(3))(2)) gives the fluxional cationic 16-electron complex [Ir(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}(2)][BAr(f) (4)] (5), which reversibly reacts with dihydrogen to afford the delta-agostic complex [IrH(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}{PPh(2)(2,6-Me(2)C(6)H(3))}][BAr(f)(4)] (6), through cleavage of an Ir-C bond. This species can also be formed by treatment of 4 with Na[BAr(f)(4)] or of 2 with Na[BAr(f)(4)] through C-H oxidative addition of one ortho-methyl group, via a transient 14-electron iridium(I) complex. Heating of the coordinatively unsaturated biscyclometalated species 5 in toluene gives the trans-dihydride iridium(III) complex [IrH(2)(CO){PPh(2)(2,6-MeC(6)H(3)CH=CHC(6)H(3)Me-2,6)PPh(2)}][BAr(f) (4)] (7), containing a trans-stilbene-type terdentate ligand, as result of a dehydrogenative carbon-carbon double bond coupling reaction, possibly through an iridium carbene species. PMID:17535000

  17. Formation of protoporphyrin IX in mouse skin after topical application of 5-aminolevulinic acid and its methyl esther

    NASA Astrophysics Data System (ADS)

    Sorensen, Roar; Juzenas, Petras; Iani, Vladimir; Moan, Johan

    1999-02-01

    Normal skin of nude mice (Balb/c) was treated topically with 5-aminolevulinic acid (ALA) and its methyl ester (ALA-Me) for 24 hours. Approximately 0.1 gram of freshly prepared cream was applied to a spot of 1 cm2 on the flank of the mice, which was then covered with a transparent dressing. The ALA induced protoporphyrin IX (PpIX) was studied by means of a noninvasive fiber-optic fluorescence probe connected to a luminescence spectrometer. The excitation wavelength was 407 nm, and the emission wavelength was 637 nm. For the first hour a slight lag in PpIX production was observed for the mice treated with ALA-Me compared to the mice treated with ALA. After approximately 12 hours the ALA and the ALA-Me treated mice showed the same PpIX fluorescence intensity. From 12 hours until 24 hours the PpIX fluorescence intensity decreased for both treatment modalities, even though ALA and ALA-Me were continuously present. At 24 hours ALA-Me-treated mice had less than half the amount of PpIX in their skin compared with ALA- treated mice.

  18. Spectrophotometric determination of benzydamine HCl, levamisole HCl and mebeverine HCl through ion-pair complex formation with methyl orange

    NASA Astrophysics Data System (ADS)

    El-Didamony, Akram M.

    2008-03-01

    A simple, rapid and sensitive spectrophotometric method has been proposed for the assay of benzydamine HCl (BENZ), levamisole HCl (LEV) and mebeverine HCl (MBV) in bulk and pharmaceutical formulations. The method based on the reaction of the selected drugs with methyl orange (MO) in buffered aqueous solution at pH 3.6. The formed yellow ion-pair complexes were extracted with dichloromethane and measured quantitatively with maximum absorption at 422 nm. The analytical parameters and their effects on the reported systems are investigated. The extracts are intensely colored and very stable at room temperature. The calibration graphs were linear over the concentration range of 2-10 μg ml -1 for BENZ, 6-24 μg ml -1 for LEV and 4-14 μg ml -1 for MBV. The stoichiometry of the reaction was found to be 1:1 in all cases and the conditional stability constant ( Kf) of the complexes have been calculated. The proposed method was successfully extended to pharmaceutical preparations-tablets. Excipients used as additive in commercial formulations did not interfere in the analysis. The proposed method can be recommended for quality control and routine analysis where time, cost effectiveness and high specificity of analytical technique are of great importance.

  19. Selective inhibition of ammonium oxidation and nitrification-linked N2O formation by methyl fluoride and dimethyl ether

    USGS Publications Warehouse

    Miller, L.G.; Coutlakis, M.D.; Oremland, R.S.; Ward, B.B.

    1993-01-01

    Methyl fluoride (CH3F) and dimethyl ether (DME) inhibited nitrification in washed-cell suspensions of Nitrosomonas europaea and in a variety of oxygenated soils and sediments. Headspace additions of CH3F (10% [vol/vol]) and DME (25% [vol/vol]) fully inhibited NO2- and N2O production from NH4+ in incubations of N. europaea, while lower concentrations of these gases resulted in partial inhibition. Oxidation of hydroxylamine (NH2OH) by N. europaea and oxidation of NO2- by a Nitrobacter sp. were unaffected by CH3F or DME. In nitrifying soils, CH3F and DME inhibited N2O production. In field experiments with surface flux chambers and intact cores, CH3F reduced the release of N2O from soils to the atmosphere by 20- to 30-fold. Inhibition by CH3F also resulted in decreased NO3- + NO2- levels and increased NH4+ levels in soils. CH3F did not affect patterns of dissimilatory nitrate reduction to ammonia in cell suspensions of a nitrate- respiring bacterium, nor did it affect N2O metabolism in denitrifying soils. CH3F and DME will be useful in discriminating N2O production via nitrification and denitrification when both processes occur and in decoupling these processes by blocking NO2- and NO3- production.

  20. Organosulfates as Tracers for Secondary Organic Aerosol (SOA) Formation from 2-Methyl-3-Buten-2-ol (MBO) in the Atmosphere

    PubMed Central

    2012-01-01

    2-Methyl-3-buten-2-ol (MBO) is an important biogenic volatile organic compound (BVOC) emitted by pine trees and a potential precursor of atmospheric secondary organic aerosol (SOA) in forested regions. In the present study, hydroxyl radical (OH)-initiated oxidation of MBO was examined in smog chambers under varied initial nitric oxide (NO) and aerosol acidity levels. Results indicate measurable SOA from MBO under low-NO conditions. Moreover, increasing aerosol acidity was found to enhance MBO SOA. Chemical characterization of laboratory-generated MBO SOA reveals that an organosulfate species (C5H12O6S, MW 200) formed and was substantially enhanced with elevated aerosol acidity. Ambient fine aerosol (PM2.5) samples collected from the BEARPEX campaign during 2007 and 2009, as well as from the BEACHON-RoMBAS campaign during 2011, were also analyzed. The MBO-derived organosulfate characterized from laboratory-generated aerosol was observed in PM2.5 collected from these campaigns, demonstrating that it is a molecular tracer for MBO-initiated SOA in the atmosphere. Furthermore, mass concentrations of the MBO-derived organosulfate are well correlated with MBO mixing ratio, temperature, and acidity in the field campaigns. Importantly, this compound accounted for an average of 0.25% and as high as 1% of the total organic aerosol mass during BEARPEX 2009. An epoxide intermediate generated under low-NO conditions is tentatively proposed to produce MBO SOA. PMID:22849588

  1. DIETARY ARSENITE AFFECTS DIMETHYLHYDRAZINE (DMH)-INDUCED ABERRANT CRYPT FORMATION IN COLON AND GLOBAL DNA METHYLATION IN LIVER OF RATS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous work has shown that arsenic (As) affects methionine metabolism. Alterations in methionine metabolism can affect cancer processes. To determine the effect of dietary As on DMH-induced aberrant crypt formation in colon Fisher-344 male, weanling rats (N=20/group) were fed diets containing 0, 0...

  2. Methane formation and methane oxidation by methanogenic bacteria.

    PubMed Central

    Zehnder, A J; Brock, T D

    1979-01-01

    Methanogenic bacteria were found to form and oxidize methane at the same time. As compared to the quantity of methane formed, the amount of methane simultaneously oxidized varied between 0.3 and 0.001%, depending on the strain used. All the nine tested strains of methane producers (Methanobacterium ruminantium, Methanobacterium strain M.o.H., M. formicicum, M. thermoautotrophicum, M. arbophilicum, Methanobacterium strain AZ, Methanosarcina barkeri, Methanospirillum hungatii, and the "acetate organism") reoxidized methane to carbon dioxide. In addition, they assimilated a small part of the methane supplied into cell material. Methanol and acetate also occurred as oxidation products in M. barkeri cultures. Acetate was also formed by the "acetate organism," a methane bacterium unable to use methanogenic substrates other than acetate. Methane was the precursor of the methyl group of the acetate synthesized in the course of methane oxidation. Methane formation and its oxidation were inhibited equally by 2-bromoethanesulfonic acid. Short-term labeling experiments with M. thermoautotrophicum and M. hungatii clearly suggest that the pathway of methane oxidation is not identical with a simple back reaction of the methane formation process. Images PMID:762019

  3. An energy-conserving pyruvate-to-acetate pathway in Entamoeba histolytica. Pyruvate synthase and a new acetate thiokinase.

    PubMed

    Reeves, R E; Warren, L G; Susskind, B; Lo, H S

    1977-01-25

    Under anaerobic conditions, cells of Entamoeba histolytica grown with bacteria produce H2 and acetate while cells grown axenically produce neither. Aerobically, acetate is produced and O2 is consumed by amebae from either type of cells. Centrifuged extracts, 2.4 x 106 x g x min, from both types of cells contain pyruvate synthase (EC 1.2.7.1) and an acetate thiokinase which, together, form a system capable of converting pyruvate to acetate. Pyruvate synthase catalyzes the reaction: pyruvate + CoA leads to CO2 + acetyl-CoA + 2E. Electron acceptors which function with this enzyme are FAD, FMN, riboflavin, ferredoxin, and methyl viologen, but not NAD or NADP. The amebal acetate thiokinase catalyzes the reaction acetyl-CoA + ADP + Pi leads to acetate + ATP + CoA. For this apparently new enzyme we suggest the trivial name acetyl-CoA-synthetase (ADP-forming). Extracts from axenic amebae do not contain hydrogenase, but extracts from cells grown with bacteria do. It is postulated that in bacteria-grown amebae electrons generated at the pyruvate synthase step are utilized anaerobically to produce H2 via the hydrogenase and that the acetyl-CoA is converted to acetate in an energy-conserving step catalyzed by amebal acetyl-CoA synthetase. Aerobically, cells grown under either regimen may utilize the energy-conserving pyruvate-to-acetate pathway since O2 then serves as the ultimate electron acceptor. PMID:13076

  4. Secondary Organic Aerosol Formation from 2-Methyl-3-Buten-2-ol Photooxidation: Evidence of Acid-Catalyzed Reactive Uptake of Epoxides

    SciTech Connect

    Zhang, Haofei; Zhang, Zhenfa; Cui, Tianqu; Lin, Ying-Hsuan; Bhathela, Neil A.; Ortega, John; Worton, David; Goldstein, Allen H.; Guenther, Alex B.; Jimenez, Jose L.; Gold, Avram; Surratt, Jason D.

    2014-04-08

    Secondary organic aerosol (SOA) formation from 2-methyl-3-buten-2-ol (MBO) photooxidation has recently been observed in both field and laboratory studies. Similar to isoprene, MBO-derived SOA increases with elevated aerosol acidity in the absence of nitric oxide; therefore, an epoxide intermediate, (3,3-dimethyloxiran-2-yl)methanol (MBO epoxide) was synthesized and tentatively proposed here to explain this enhancement. In the present study, the potential of the synthetic MBO epoxide to form SOA via reactive uptake was systematically examined. SOA was observed only in the presence of acidic aerosols. Major SOA constituents, 2,3-dihydroxyisopentanol (DHIP) and MBO-derived organosulfate isomers, were chemically characterized in both laboratory-generated SOA and in ambient fine aerosols collected from the BEACHON-RoMBAS field campaign during summer 2011, where MBO emissions are substantial. Our results support epoxides as potential products of MBO photooxidation leading to formation of atmospheric SOA and suggest that reactive uptake of epoxides may generally explain acid enhancement of SOA observed from other biogenic hydrocarbons.

  5. Formation of 4-keto-D-aldopentoses and 4-pentulosonates (4-keto-D-pentonates) with unidentified membrane-bound enzymes from acetic acid bacteria.

    PubMed

    Adachi, Osao; Hours, Roque A; Shinagawa, Emiko; Akakabe, Yoshihiko; Yakushi, Toshiharu; Matsushita, Kazunobu

    2011-01-01

    In our previous study, a new microbial reaction yielding 4-keto-D-arabonate from 2,5-diketo-D-gluconate was identified with Gluconacetobacter liquefaciens RCTMR 10. It appeared that decarboxylation and dehydrogenation took place together in the reaction. To analyze the nature of the reaction, investigations were done with the membrane fraction of the organism, and 4-keto-D-arabinose was confirmed as the direct precursor of 4-keto-D-arabonate. Two novel membrane-bound enzymes, 2,5-diketo-D-gluconate decarboxylase and 4-keto-D-aldopentose 1-dehydrogenase, were involved in the reaction. Alternatively, D-arabonate was oxidized to 4-keto-D-arabonate by another membrane-bound enzyme, D-arabonate 4-dehydrogenase. More directly, D-arabinose oxidation was examined with growing cells and with the membrane fraction of G. suboxydans IFO 12528. 4-Keto-D-arabinose, the same intermediate as that from 2,5-diketo-D-gluconate, was detected, and it was oxidized to 4-keto-D-arabonate. Likewise, D-ribose was oxidized to 4-keto-D-ribose and then it was oxidized to 4-keto-D-ribonate. In addition to 4-keto-D-aldopentose 1-dehydrogenase, the presence of a novel membrane-bound enzyme, D-aldopentose 4-dehydrogenase, was confirmed in the membrane fraction. The formation of 4-keto-D-aldopentoses and 4-keto-D-pentonates (4-pentulosonates) was finally confirmed as reaction products of four different novel membrane-bound enzymes. PMID:21897028

  6. The C-H bond activation in 1-ethyl-3-methylimidazolium acetate-copper(II) acetate-water-air (dioxygen) systems.

    PubMed

    Shtyrlin, Valery G; Serov, Nikita Yu; Islamov, Daut R; Konkin, Alexander L; Bukharov, Mikhail S; Gnezdilov, Oleg I; Krivolapov, Dmitry B; Kataeva, Ol'ga N; Nazmutdinova, Gulnara A; Wendler, Frank

    2014-01-14

    Ionic liquid (1-ethyl-3-methylimidazolium acetate, [C2C1im][AcO])-copper(ii) diacetate monohydrate-water-air (O2) systems have been investigated by (13)C NMR, EPR, spectrophotometry, HPLC, and synthetic chemistry methods at different temperatures. The C-H bond activation of [C2C1im](+) with the formation of the unusual dication 1,1'-diethyl-3,3'-dimethyl-2,2'-biimidazolium ([(C2C1im)2](2+)) at 50 °C and 1-ethyl-3-methyl-1H-imidazol-2(3H)-one (C2C1imO) at 50-85 °C was revealed. Two new complexes with the above compounds, [(C2C1im)2][Cu(AcO)4] and Cu2(AcO)4(C2C1imO)2, were isolated from the systems and characterized by X-ray structural analysis. Catalytic cycles with the participation of copper(ii) acetate and dioxygen and the production of [(C2C1im)2](2+) and C2C1imO have been proposed. The catalysis presumably includes the formation of the Cu(II)(O2)Cu(II) active centre with μ-η(2):η(2)-peroxide bridging in analogy with tyrosinase and catechol oxidase activity. PMID:24154681

  7. Leisingera methylohalidivorans gen. nov., sp. nov., a marine methylotroph that grows on methyl bromide

    USGS Publications Warehouse

    Schaefer, J.K.; Goodwin, K.D.; McDonald, I.R.; Murrell, J.C.; Oremland, R.S.

    2002-01-01

    A marine methylotroph, designated strain MB2T, was isolated for its ability to grow on methyl bromide as a sole carbon and energy source. Methyl chloride and methyl iodide also supported growth, as did methionine and glycine betaine. A limited amount of growth was observed with dimethyl sulfide. Growth was also noted with unidentified components of the complex media marine broth 2216, yeast extract and Casamino acids. No growth was observed on methylated amines, methanol, formate, acetate, glucose or a variety of other substrates. Growth on methyl bromide and methyl iodide resulted in their oxidation to CO2 with stoichiometric release of bromide and iodide, respectively. Strain MB2T exhibited growth optima at NaCl and Mg2+ concentrations similar to that of seawater. Phylogenetic analysis of the 16S rDNA sequence placed this strain in the ??-Proteobacteria in proximity to the genera Ruegeria and Roseobacter. It is proposed that strain MB2T (= ATCC BAA-92T = DSM 14336T) be designated Leisingera methylohalidivorans gen. nov., sp. nov.

  8. Acetic Acid Reforming over Rh Supported on La2O3/CeO2-ZrO2: Catalytic Performance and Reaction Pathway Analysis

    SciTech Connect

    Lemonidou, Angeliki A.; Vagia, Ekaterini C.; Lercher, Johannes A.

    2013-07-11

    Reforming of acetic acid was investigated on Rh supported on CeO2-ZrO2 modified with 3 wt % La. The active catalyst converted acetic acid to H-2-rich gas and hardly formed coke. The low rate of coke formation is concluded to be related to the presence of redox-active oxygen limiting the concentration of coke precursors. Temperature-programmed O-18(2)) isotope exchange measurements showed that the La2O3 and Rh enhanced the mobility of lattice oxygen compared with that of the parent CeO2-ZrO2. Ketonization and decarboxylation of acetic acid are the dominating reactions over the latter up to 600 degrees C, whereas above 600 degrees C, steam reforming and water gas shift also contribute. Over 0.5 wt % Rh on La2O3/CeO2-ZrO2, reforming and water gas shift reactions dominate, even below 300 degrees C, producing mostly H-2 and CO2. Using isotope labeling, it is shown that acetic acid adsorbs dissociatively on Rh, forming acetates, which sequentially decarboxylate and form surface methyl groups. The latter are in turn converted to CO, CO2, and H-2.

  9. DNA methylation in plants.

    PubMed

    Vanyushin, B F

    2006-01-01

    DNA in plants is highly methylated, containing 5-methylcytosine (m5C) and N6-methyladenine (m6A); m5C is located mainly in symmetrical CG and CNG sequences but it may occur also in other non-symmetrical contexts. m6A but not m5C was found in plant mitochondrial DNA. DNA methylation in plants is species-, tissue-, organelle- and age-specific. It is controlled by phytohormones and changes on seed germination, flowering and under the influence of various pathogens (viral, bacterial, fungal). DNA methylation controls plant growth and development, with particular involvement in regulation of gene expression and DNA replication. DNA replication is accompanied by the appearance of under-methylated, newly formed DNA strands including Okazaki fragments; asymmetry of strand DNA methylation disappears until the end of the cell cycle. A model for regulation of DNA replication by methylation is suggested. Cytosine DNA methylation in plants is more rich and diverse compared with animals. It is carried out by the families of specific enzymes that belong to at least three classes of DNA methyltransferases. Open reading frames (ORF) for adenine DNA methyltransferases are found in plant and animal genomes, and a first eukaryotic (plant) adenine DNA methyltransferase (wadmtase) is described; the enzyme seems to be involved in regulation of the mitochondria replication. Like in animals, DNA methylation in plants is closely associated with histone modifications and it affects binding of specific proteins to DNA and formation of respective transcription complexes in chromatin. The same gene (DRM2) in Arabidopsis thaliana is methylated both at cytosine and adenine residues; thus, at least two different, and probably interdependent, systems of DNA modification are present in plants. Plants seem to have a restriction-modification (R-M) system. RNA-directed DNA methylation has been observed in plants; it involves de novo methylation of almost all cytosine residues in a region of si

  10. Effect of Exogenous Indole-3-Acetic Acid and Indole-3-Butyric Acid on Internal Levels of the Respective Auxins and Their Conjugation with Aspartic Acid during Adventitious Root Formation in Pea Cuttings.

    PubMed

    Nordström, A C; Jacobs, F A; Eliasson, L

    1991-07-01

    The influence of exogenous indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) on the internal levels of these auxins was studied during the first 4 days of adventitious root formation in cuttings of Pisum sativum L. The quantitations were done by high performance liquid chromatography with spectrofluorometric detection. IBA, identified by combined gas chromatography-mass spectrometry (GC-MS), was found to naturally occur in this plant material. The root inducing ability of exogenous IBA was superior to that of IAA. The IAA level in the tissue increased considerably on the first day after application of IAA, but rapidly decreased again, returning to a level twice the control by day 3. The predominant metabolic route was conjugation with aspartic acid, as reflected by the increase in the level of indole-3-acetylaspartic acid. The IBA treatment resulted in increases in the levels of IBA, IAA, and indole-3-acetylaspartic acid. The IAA content rapidly returned to control levels, whereas the IBA level remained high throughout the experimental period. High amounts of indole-3-butyrylaspartic acid were found in the tissue after feeding with IBA. The identity of the conjugate was confirmed by (1)H-nuclear magnetic resonance and GC-MS. IBA was much more stable in solution than IAA. No IAA was detected after 48 hours, whereas 70% IBA was still recovered after this time. The relatively higher root inducing ability of IBA is ascribed to the fact that its level remained elevated longer than that of IAA, even though IBA was metabolized in the tissue. Adventitious root formation is discussed on the basis of these findings. PMID:16668265

  11. 3-Isopropyl-1-{2-[(1-methyl-1H-tetra-zol-5-yl)sulfan-yl]acet-yl}-2,6-di-phenyl-piperidin-4-one hemihydrate.

    PubMed

    Ganesan, S; Sugumar, P; Ananthan, S; Ponnuswamy, M N

    2013-10-01

    In the title compound, C24H27N5O2S·0.5H2O, the piperidine ring adopts a distorted boat conformation. The phenyl rings subtend dihedral angles of 69.7 (1) and 88.7 (1)° with the best plane through the piperidine moiety. In the crystal, symmetry-related mol-ecules are linked through a network of C-H⋯O and C-H⋯N inter-actions, the former connecting them into zigzag chains along the c-axis direction and the latter forming an R (2) 2(4)motif. The dimer formation (C-H⋯N) and the repetition of symmetry-related molecules (C-H⋯O) along the b-axis direction stabilize the packing mode. The water mol-ecule is located on a twofold rotation axis. PMID:24454052

  12. Box C/D RNA guides for the ribose methylation of archaeal tRNAs. The tRNATrp intron guides the formation of two ribose-methylated nucleosides in the mature tRNATrp

    PubMed Central

    d’Orval, Béatrice Clouet; Bortolin, Marie-Line; Gaspin, Christine; Bachellerie, Jean-Pierre

    2001-01-01

    Following a search of the Pyrococcus genomes for homologs of eukaryotic methylation guide small nucleolar RNAs, we have experimentally identified in Pyrococcus abyssi four novel box C/D small RNAs predicted to direct 2′-O-ribose methylations onto the first position of the anticodon in tRNALeu(CAA), tRNALeu(UAA), elongator tRNAMet and tRNATrp, respectively. Remarkably, one of them corresponds to the intron of its presumptive target, pre-tRNATrp. This intron is predicted to direct in cis two distinct ribose methylations within the unspliced tRNA precursor, not only onto the first position of the anticodon in the 5′ exon but also onto position 39 (universal tRNA numbering) in the 3′ exon. The two intramolecular RNA duplexes expected to direct methylation, which both span an exon–intron junction in pre-tRNATrp, are phylogenetically conserved in euryarchaeotes. We have experimentally confirmed the predicted guide function of the box C/D intron in halophile Haloferax volcanii by mutagenesis analysis, using an in vitro splicing/RNA modification assay in which the two cognate ribose methylations of pre-tRNATrp are faithfully reproduced. Euryarchaeal pre-tRNATrp should provide a unique system to further investigate the molecular mechanisms of RNA-guided ribose methylation and gain new insights into the origin and evolution of the complex family of archaeal and eukaryotic box C/D small RNAs. PMID:11713301

  13. Positron scattering from vinyl acetate

    NASA Astrophysics Data System (ADS)

    Chiari, L.; Zecca, A.; Blanco, F.; García, G.; Brunger, M. J.

    2014-09-01

    Using a Beer-Lambert attenuation approach, we report measured total cross sections (TCSs) for positron scattering from vinyl acetate (C4H6O2) in the incident positron energy range 0.15-50 eV. In addition, we also report an independent atom model with screening corrected additivity rule computation results for the TCSs, differential and integral elastic cross sections, the positronium formation cross section and inelastic integral cross sections. The energy range of these calculations is 1-1000 eV. While there is a reasonable qualitative correspondence between measurement and calculation for the TCSs, in terms of the energy dependence of those cross sections, the theory was found to be a factor of ˜2 larger in magnitude at the lower energies, even after the measured data were corrected for the forward angle scattering effect.

  14. Acetate Dependence of Tumors

    PubMed Central

    Comerford, Sarah A.; Huang, Zhiguang; Du, Xinlin; Wang, Yun; Cai, Ling; Witkiewicz, Agnes; Walters, Holly; Tantawy, Mohammed N.; Fu, Allie; Manning, H. Charles; Horton, Jay D.; Hammer, Robert E.; McKnight, Steven L.; Tu, Benjamin P.

    2014-01-01

    SUMMARY Acetyl-CoA represents a central node of carbon metabolism that plays a key role in bioenergetics, cell proliferation and the regulation of gene expression. How highly glycolytic or hypoxic tumors are able to produce sufficient quantities of this metabolite to support cell growth and survival under nutrient-limiting conditions remains poorly understood. Here we show that the nucleocytosolic acetyl-CoA synthetase enzyme, ACSS2, supplies a key source of acetyl-CoA for tumors by capturing acetate as a carbon source. Despite exhibiting no gross deficits in growth or development, adult mice lacking ACSS2 exhibit a significant reduction in tumor burden in two different models of hepatocellular carcinoma. ACSS2 is expressed in a large proportion of human tumors and its activity is responsible for the majority of cellular acetate uptake into both lipids and histones. These observations may qualify ACSS2 as a targetable metabolic vulnerability of a wide spectrum of tumors. PMID:25525877

  15. Formation of 3-methyl-1,2,3-butanetricarboxylic acid via gas phase oxidation of pinonic acid - a mass spectrometric study of SOA aging

    NASA Astrophysics Data System (ADS)

    Müller, L.; Reinnig, M. C.; Naumann, K. H.; Saathoff, H.; Mentel, T. F.; Donahue, N. M.; Hoffmann, T.

    2011-07-01

    This paper presents the results of mass spectrometric investigations of the OH-initiated oxidative aging of α-pinene SOA under simulated tropospheric conditions at the large aerosol chamber facility AIDA, Karlsruhe Institute of Technology. In particular, the OH-initiated oxidation of pure pinic and pinonic acid, two well-known oxidation products of α-pinene, was investigated. Two complementary analytical techniques were used, on-line atmospheric pressure chemical ionization/mass spectrometry (APCI/MS) and filter sampling followed by liquid chromatography/mass spectrometry (LC/ESI-MS). The results show that 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a known and very low volatile α-pinene SOA product, is formed from the oxidation of pinonic acid and that this oxidation takes place in the gas phase. This finding is confirmed by temperature-dependent aging experiments on whole SOA formed from α-pinene, in which the yield of MBTCA scales with the pinonic acid fraction in the gas phase. Based on the results, several feasible gas-phase radical mechanisms are discussed to explain the formation of MBTCA from OH-initiated pinonic acid oxidation.

  16. Formation of 3-methyl-1,2,3-butanetricarboxylic acid via gas phase oxidation of pinonic acid - a mass spectrometric study of SOA aging

    NASA Astrophysics Data System (ADS)

    Müller, L.; Reinnig, M.-C.; Naumann, K. H.; Saathoff, H.; Mentel, T. F.; Donahue, N. M.; Hoffmann, T.

    2012-02-01

    This paper presents the results of mass spectrometric investigations of the OH-initiated oxidative aging of α-pinene SOA under simulated tropospheric conditions at the large aerosol chamber facility AIDA, Karlsruhe Institute of Technology. In particular, the OH-initiated oxidation of pure pinic and pinonic acid, two well-known oxidation products of α-pinene, was investigated. Two complementary analytical techniques were used, on-line atmospheric pressure chemical ionization/mass spectrometry (APCI/MS) and filter sampling followed by liquid chromatography/mass spectrometry (LC/ESI-MS). The results show that 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a very low volatile α-pinene SOA product and a tracer compound for terpene SOA, is formed from the oxidation of pinonic acid and that this oxidation takes place in the gas phase. This finding is confirmed by temperature-dependent aging experiments on whole SOA formed from α-pinene, in which the yield of MBTCA scales with the pinonic acid fraction in the gas phase. Based on the results, several feasible gas-phase radical mechanisms are discussed to explain the formation of MBTCA from OH-initiated pinonic acid oxidation.

  17. Roles of tert-butyl formate, tert-butyl alcohol and acetone in the regulation of methyl tert-butyl ether degradation by Mycobacterium austroafricanum IFP 2012.

    PubMed

    François, A; Garnier, L; Mathis, H; Fayolle, F; Monot, F

    2003-08-01

    Mycobacterium austroafricanum IFP 2012 is a Gram-positive strain able to grow on methyl tert-butyl ether (MTBE) as a sole carbon and energy source. The effect of two downstream metabolites of MTBE, tert-butyl formate (TBF) and tert-butyl alcohol (TBA) on MTBE degradation was investigated using resting cells. The addition of low concentrations of TBF decreased the MTBE degradation rate by about 30%. In contrast, the addition of TBA did not have a significant effect on MTBE degradation rate, even at high concentrations; and it was also shown that TBA degradation occurred only once MTBE was exhausted. At neutral pH, TBF hydrolysis involved mainly an esterase-type activity regulated by the presence of TBA. The TBF degradation rate was about four times lower than the MTBE degradation rate. Furthermore, acetone was identified as an intermediate during TBA degradation. An acetone mono-oxygenase activity, inhibited by methimazole but not by acetylene, was suggested. It was different from the MTBE/TBA mono-oxygenase and, thus, acetone did not appear to compete with MTBE and TBA for the same enzyme. These new results show that the metabolic regulation of the early steps of MTBE degradation by M. austroafricanum IFP 2012 is complex, involving inhibition and competition phenomena. PMID:12883872

  18. The in-situ formation of methyl-nitrate during NOx re-cycling involving CH3O2: global impacts and implications in the troposphere

    NASA Astrophysics Data System (ADS)

    Williams, Jason; Le Bras, Georges; Kukui, Alexandre

    2013-04-01

    Organic nitrates are formed via chain termination steps involving peroxy-radicals and NO thus impacting the efficiency of ozone production and global oxidative capacity, especially in low NOx environments (Browne and Cohen, 2012). Recently the direct formation of methyl nitrate (CH3ONO2) has been observed during the re-cycling of NOx by CH3O2 (Butkovskaya et al., 2012) with a branching ratio of 1.0(+/-)0.7% for tropospheric conditions. Considering that the CH3O2 route acts as the second most important radical mechanism of NOx re-cycling at global scale implies that this sequestration of reactive nitrogen into a more long lived reservoir could potentially decrease the efficiency of tropospheric ozone production, especially in the tropical regions where the highest mixing ratios of CH3O2 exist as a result of methane oxidation. Past measurements of alkyl-nitrates have shown that although resident mixing ratios of organic nitrates are high under urban conditions, they are also present in the more pristine regions of the tropical Pacific (e.g. Blake et al, 2003) and above Antarctica (i.e. in low NOx environments). Using the global 3D TM5 model we investigate the impact that the direct in-situ formation of CH3ONO2 has on global tropospheric composition. By comparing against measurements we also show that such a process could go part way towards explaining the distribution of CH3ONO2 in the tropical troposphere, where direct emissions from the ocean have previously been used to explain observations (Neu et al, 2008). Browne and Cohen, Atms. Chem. Phys., 12, 11917-11932, 2012. Butkovskaya et al., J. Phys. Chem. A., 116(24), 5972-5980, 2012. Blake et al., J. Geophys. Res., 108(D2), 8242, 2003. Neu et al., Geophys. Res. Letts., 35, L13814, 2008.

  19. Methyl Iodide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl iodide (MeI, iodomethane, CH3I) was reported as a potential alternative to the stratospheric ozone-depleting fumigant methyl bromide (MeBr) in the mid-1990s (Sims et al., 1995; Ohr et al., 1996). It has since received significant research attention to determine its environmental fate and tran...

  20. Methyl chloroform

    SciTech Connect

    Wray, T.K.

    1994-04-01

    Methyl chloroform is identified as a Class 1 ozone-depleting substance under Title VI of the CAA Amendments. On Nov. 30, 1993, EPA ordered the phaseout of Class 1 ozone-depleting substances -- chlorofluorocarbons (CFCs), halons, carbon tetrachloride and methyl chloroform -- by Jan. 1, 1996. Methyl chloroform and other Class 1 substances may be used after the dead-line if sources can be found through recycling or existing inventories. Methyl chloroform is listed as a hazardous air pollutant under CAA. It also is a SARA Title III, Sec. 313 compound with a reportable quantity of 1,000 pounds. OSHA and the American Conference of Government Industrial Hygienists have set 350 ppm as the time-weighted average airborne exposure level for methyl chloroform. NIOSH lists its immediately dangerous to life or health'' concentration as 1,000 parts per million. DOT identifies the substance as a hazardous material, Class 6.1 (poison).

  1. New strategy to address DNA-methyl transferase activity in ovarian cancer cell cultures by monitoring the formation of 5-methylcytosine using HPLC-UV.

    PubMed

    Iglesias González, T; Blanco-González, E; Montes-Bayón, M

    2016-08-15

    Methylation of mammalian genomic DNA is catalyzed by DNA methyltransferases (DNMTs). Aberrant expression and activity of these enzymes has been reported to play an important role in the initiation and progression of tumors and its response to chemotherapy. Therefore, there is a great interest in developing strategies to detect human DNMTs activity. We propose a simple, antibody-free, label-free and non-radioactive analytical strategy in which methyltransferase activity is measured trough the determination of the 5-methylcytosine (5mC) content in DNA by a chromatographic method (HPLC-UV) previously developed. For this aim, a correlation between the enzyme activity and the concentration of 5mC obtained by HPLC-UV is previously obtained under optimized conditions using both, un-methylated and hemi-methylated DNA substrates and the prokaryotic methyltransferase M.SssI as model enzyme. The evaluation of the methylation yield in un-methylated known sequences (a 623bp PCR-amplicon) turned to be quantitative (110%) in experiments conducted in-vitro. Methylation of hemi-methylated and low-methylated sequences could be also detected with the proposed approach. The application of the methodology to the determination of the DNMTs activity in nuclear extracts from human ovarian cancer cells has revealed the presence of matrix effects (also confirmed by standard additions) that hampered quantitative enzyme recovery. The obtained results showed the high importance of adequate sample clean-up steps. PMID:27318640

  2. Chemistry of enol ethers. LXXXIV. Condensation of acetals of saturated aldehydes with 2-trimethylsilyloxy-1,3-dienes. Synthesis of /beta/-alkoxy-alkyl vinyl and divinyl ketones

    SciTech Connect

    Makin, S.M.; Nazarova, O.N.; Dymshakova, G.M.; Kundryutskova, L.A.

    1988-11-10

    The addition of the acetals of saturated aldehydes (formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, and isobutyraldehyde) to 2-trimethylsilyloxy-4-methyl-1,3-pentadiene in the presence of aprotic acids (ZnCl/sub 2/, ZnBr/sub 2/, FeCl/sub 3/, SnCl/sub 4/, BF/sub 3/ /times/ OEt/sub 2/) takes place at positions 1, 2 of the diene system with the formation of /beta/-alkoxyalkyl vinyl ketones. The most effective catalysts of this reaction were stannic chloride and zinc bromide. The alkyl derivatives of divinyl ketones are formed when the obtained /beta/-alkoxyalkyl vinyl ketones are heated with p-toluenesulfonic acid.

  3. Evidence that the production of acetate in rat hepatocytes is a predominantly cytoplasmic process.

    PubMed Central

    Crabtree, B; Souter, M J; Anderson, S E

    1989-01-01

    By using [1-14C]butyrate, the fluxes of butyrate to acetate and fatty acids were measured in rat hepatocytes. Both fluxes were inhibited to a similar extent by (-)-hydroxycitrate, with no significant effect on butyrate uptake. These results indicate that acetate formation takes place in the cytoplasm, presumably via ATP-stimulated acetyl-CoA hydrolase. Since acetate formation occurred despite a net uptake of acetate, the results are also consistent with the operation of a substrate cycle between acetate and acetyl-CoA, recently proposed by other workers, and suggest that this cycle is cytoplasmic. PMID:2564776

  4. Comparison of Acetate Turnover in Methanogenic and Sulfate-Reducing Sediments by Radiolabeling and Stable Isotope Labeling and by Use of Specific Inhibitors: Evidence for Isotopic Exchange

    PubMed Central

    de Graaf, W.; Wellsbury, P.; Parkes, R. J.; Cappenberg, T. E.

    1996-01-01

    Acetate turnover in the methanogenic freshwater anoxic sediments of Lake Vechten, The Netherlands, and in anoxic sediments from the Tamar Estuary, United Kingdom, and the Grosser Jasmunder Bodden, Germany, the latter two dominated by sulfate reduction, was determined. Stable isotopes and radioisotopes, inhibitors (chloroform and fluoroacetate), and methane flux were used to provide independent estimates of acetate turnover. Pore water acetate pool sizes were determined by gas chromatography with a flame ionization detector, and stable isotope-labeled acetate was determined by gas chromatography-mass spectrometry. The appearance of acetates with a different isotope labeling pattern from that initially added demonstrated that isotopic exchange occurred during methanogenic acetate metabolism. The predominant exchange processes were (i) D-H exchange in the methyl group and (ii) (sup13)C-(sup12)C exchange at the carboxyl carbon. These exchanges are most probably caused by the activity of the enzyme complex carbon monoxide dehydrogenase and subsequent methyl group dehydrogenation by tetrahydromethanopterine or a related enzyme. The methyl carbon was not subject to exchange during transformation to methane, and hence acetate with the methyl carbon labeled will provide the most reliable estimate of acetate turnover to methane. Acetate turnover rate estimates with these labels were consistent with independent estimates of acetate turnover (acetate accumulation after inhibition and methane flux). Turnover rates from either radioisotope- or stable isotope-labeled methyl carbon isotopes are, however, dependent on accurate determination of the acetate pool size. The additions of large amounts of stable isotope-labeled acetate elevate the acetate pool size, stimulating acetate consumption and causing deviation from steady-state kinetics. This can, however, be overcome by the application of a non-steady-state model. Isotopic exchange in sediments dominated by sulfate reduction

  5. Exposure of E. coli to DNA-Methylating Agents Impairs Biofilm Formation and Invasion of Eukaryotic Cells via Down Regulation of the N-Acetylneuraminate Lyase NanA.

    PubMed

    Di Pasquale, Pamela; Caterino, Marianna; Di Somma, Angela; Squillace, Marta; Rossi, Elio; Landini, Paolo; Iebba, Valerio; Schippa, Serena; Papa, Rosanna; Selan, Laura; Artini, Marco; Palamara, Anna Teresa; Palamara, Annateresa; Duilio, Angela

    2016-01-01

    DNA methylation damage can be induced by endogenous and exogenous chemical agents, which has led every living organism to develop suitable response strategies. We investigated protein expression profiles of Escherichia coli upon exposure to the alkylating agent methyl-methane sulfonate (MMS) by differential proteomics. Quantitative proteomic data showed a massive downregulation of enzymes belonging to the glycolytic pathway and fatty acids degradation, strongly suggesting a decrease of energy production. A strong reduction in the expression of the N-acetylneuraminate lyases (NanA) involved in the sialic acid metabolism was also observed. Using a null NanA mutant and DANA, a substrate analog acting as competitive inhibitor, we demonstrated that down regulation of NanA affects biofilm formation and adhesion properties of E. coli MV1161. Exposure to alkylating agents also decreased biofilm formation and bacterial adhesion to Caco-2 eukaryotic cell line by the adherent invasive E. coli (AIEC) strain LF82. Our data showed that methylation stress impairs E. coli adhesion properties and suggest a possible role of NanA in biofilm formation and bacteria host interactions. PMID:26904018

  6. Exposure of E. coli to DNA-Methylating Agents Impairs Biofilm Formation and Invasion of Eukaryotic Cells via Down Regulation of the N-Acetylneuraminate Lyase NanA

    PubMed Central

    Di Pasquale, Pamela; Caterino, Marianna; Di Somma, Angela; Squillace, Marta; Rossi, Elio; Landini, Paolo; Iebba, Valerio; Schippa, Serena; Papa, Rosanna; Selan, Laura; Artini, Marco; Palamara, Anna Teresa; Duilio, Angela

    2016-01-01

    DNA methylation damage can be induced by endogenous and exogenous chemical agents, which has led every living organism to develop suitable response strategies. We investigated protein expression profiles of Escherichia coli upon exposure to the alkylating agent methyl-methane sulfonate (MMS) by differential proteomics. Quantitative proteomic data showed a massive downregulation of enzymes belonging to the glycolytic pathway and fatty acids degradation, strongly suggesting a decrease of energy production. A strong reduction in the expression of the N-acetylneuraminate lyases (NanA) involved in the sialic acid metabolism was also observed. Using a null NanA mutant and DANA, a substrate analog acting as competitive inhibitor, we demonstrated that down regulation of NanA affects biofilm formation and adhesion properties of E. coli MV1161. Exposure to alkylating agents also decreased biofilm formation and bacterial adhesion to Caco-2 eukaryotic cell line by the adherent invasive E. coli (AIEC) strain LF82. Our data showed that methylation stress impairs E. coli adhesion properties and suggest a possible role of NanA in biofilm formation and bacteria host interactions. PMID:26904018

  7. Catalytic purification of wastewaters containing formaldehyde, methyl alcohol, and acetone

    SciTech Connect

    Rachkovskaya, L.N.; Anisiforov, G.I.; Levitskii, E.A.; Kundo, N.N.

    1982-01-10

    A catalytic method for purification of wastewaters containing alcohols, aldehydes, and ketones is described in the literature. A current of steam containing gaseous organic compounds is passed over a complete-oxidation catalyst at temperatures of 250-700/sup 0/C. The organic compounds are oxidized to carbon dioxide. The main drawback of this method is that the wastewater must be evaporated and the vapor heated to high temperatures, involving a high consumption of fuel. Methods of liquid-phase catalytic oxidation under pressure are free from this drawback. A patent describes liquid-phase oxidation of phenol, analine, nitrobenzene, glycol, and dimethylformamide at temperatures of 275-300/sup 0/C under air pressures up to 100 atm in presence of oxides of copper, chromium, and zinc; a metallic catalyst consisting of copper, chromium, and manganese; copper oxide deposited on magnesium silicate. In a contact time of 8-10 min the degree of oxidation is 90-99%. It is known that liquid-phase oxidation of formaldehyde without a catalyst at 200/sup 0/C and 120 atm with a contact time of 4 h results in 80% oxidation of formaldehyde to methyl formate undergoes 10% conversion into acetic acid, while methyl alcohol is not oxidized at all. In this communication we describe liquid-phase catalytic oxidation of model wastewater containing formaldehyde, methyl alcohol, and acetone at temperatures up to 250/sup 0/C and oxygen pressures up to 20 atm.

  8. Fragrance material review on phenethyl acetate.

    PubMed

    McGinty, D; Vitale, D; Letizia, C S; Api, A M

    2012-09-01

    A toxicologic and dermatologic review of phenethyl acetate when used as a fragrance ingredient is presented. Phenethyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for phenethyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, elicitation, toxicokinetics, repeated dose, genotoxicity, and carcinogenicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414644

  9. CRYSTAL AND MOLECULAR STRUCTURE OF 6,6´-DIMETHOXY-GOSSYPOL:ACETIC ACID (1:1)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    By crystallization from dilute solutions of acetic acid (2-4%) in diethyl ether, acetone, or methyl ethyl ketone, 6,6´-dimethoxy-gossypol forms an inclusion complex with acetic acid in a one-to-one molar ratio. The compound crystallizes in the triclinic P1bar1¯space group and has unit cell dimensio...

  10. The stable carbon isotope biogeochemistry of acetate and methane in freshwater environments

    SciTech Connect

    Gelwicks, J.T.

    1989-01-01

    Methane produced in freshwater sediments, where acetate is the major substrate utilized by methanogenic bacteria, is commonly depleted in {sup 13}C. Variations in the carbon-isotopic composition of methane have been related to flows of acetate carbon to various fates within microbial communities. To examine these processes, the isotopic compositions of biogenic methane and its sedimentary sources (acetate and CO{sub 2}) were considered along with related isotope effects. A method of preparation for carbon isotope analyses of both carbons in acetate was developed. Uncertainties in measurements are less than 0.4{per thousand} for samples greater than 5 {mu}mol of acetate. Advantages of this technique include good separation of acetate from other compounds and the applicability to samples containing micromolar quantities of acetate. Carbon kinetic isotope effects associated with synthesis of acetate from CO{sub 2} by Acetobacterium woodii were measured by isotopic analyses of CO{sub 2}, methyl-carbon, and total acetate. Closed systems allowing construction of complete mass balances at varying stages of growth were utilized, and the effects of the partitioning of carbon between CO{sub 2} and HCO{sub 3}{sup {minus}} were taken into account. For the overall reaction total carbonate {yields} total acetate, the isotope effect measured {minus}58.6 {plus minus} 0.7{per thousand}; there is no evidence for intramolecular isotopic ordering in the acetate. Carbon isotope effects associated with synthesis of methane from acetate by Methanosarcina barkeri and by a natural community of methanogens were measured in closed system experiments. For the process of methyl-carbon {yields} methane, the isotope effect measured {minus}21.5 {plus minus} 1.3{per thousand}.

  11. Methane Production and Syntrophic Acetate Oxidation in the Florida Everglades

    NASA Astrophysics Data System (ADS)

    Holmes, M. E.; Chanton, J.; Bae, H.; Ogram, A.

    2012-12-01

    Methane production pathways in the Florida Everglades are influenced by factors such as nutrient levels, H2 concentrations, and temperature. Syntrophic acetate oxidizers can outcompete methanogens for acetate when conditions are right (high temperatures and low H2). During syntrophic acetate oxidation (SAO), which becomes more exergonic with increasing temperature, acetate is oxidized to carbon dioxide and H2, which can be utilized to produce methane via CO2 reduction. Everglades soil from along a nutrient gradient was incubated at 25°C and 45°C. The shift to the CO2 reduction pathway for methane formation that would be expected in high temperature incubations due to SAO should result in a decrease in δ13C-CH4 and increase in δ2H-CH4. Instead, we observed higher δ13C and lower δ2H in the methane produced in high temperature incubations. The higher than expected δ13C may be partly explained by lower kinetic isotope effects caused by temperature. Coupling between the syntrophic acetate oxidizers and the CO2 reducers, whereby isotopically light hydrogen from acetate is used in methane formation could lower δ2H-CH4. Separate experiments using 13C-labelled acetate revealed that potential SAO activity is low in soils collected from the Everglades.

  12. [Nomegestrol acetate: clinical pharmacology].

    PubMed

    Lello, S

    2009-10-01

    Progestogens are used in clinical practice in some conditions. Their effects depend on their chemical structure, pharmacokinetics, pharmacodynamics, with important differences among various progestogens. Generally, progestins are classified according to their parent molecule, of which often they keep some features. Derivatives of 19-nor-progesterone are characterized by high selectivity of action on progestin receptor. In particular, nomegestrol acetate (NomAc) shows an important progestational potency, neutral gluco-lipid profile, and antigonadotropic activity. It is used for treating menstrual cycle disorders and for hormone replacement therapy in menopause in association with an estrogen. In future, thanks to its antigonadotropic activity, NomAc will be used in estroprogestin combinations in fertile women, thus taking advantage of its tolerability profile and obtaining numerous non-contraceptive benefits as well. PMID:19749678

  13. Simultaneous Determination of Salicylic Acid, Jasmonic Acid, Methyl Salicylate, and Methyl Jasmonate from Ulmus pumila Leaves by GC-MS

    PubMed Central

    Huang, Zhi-hong; Wang, Zhi-li; Shi, Bao-lin; Wei, Dong; Chen, Jian-xin; Wang, Su-li; Gao, Bao-jia

    2015-01-01

    Salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate are important phytohormones and defensive signaling compounds, so it is of great importance to determine their levels rapidly and accurately. The study uses Ulmus pumila leaves infected by Tetraneura akinire Sasaki at different stages as materials; after extraction with 80% methanol and ethyl acetate and purification with primary secondary amine (PSA) and graphitized carbon blacks (GCB), the contents of signal compounds salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate were determined by GC-MS. The results showed that the level of salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate increased remarkably in U. pumila once infected by T. akinire Sasaki, but the maximums of these four compounds occurred at different times. Salicylic acid level reached the highest at the early stage, and jasmonic acid level went to the maximum in the middle stage; by contrast, change of content of methyl salicylate and methyl jasmonate was the quite opposite. PMID:26457083

  14. Simultaneous Determination of Salicylic Acid, Jasmonic Acid, Methyl Salicylate, and Methyl Jasmonate from Ulmus pumila Leaves by GC-MS.

    PubMed

    Huang, Zhi-Hong; Wang, Zhi-Li; Shi, Bao-Lin; Wei, Dong; Chen, Jian-Xin; Wang, Su-Li; Gao, Bao-Jia

    2015-01-01

    Salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate are important phytohormones and defensive signaling compounds, so it is of great importance to determine their levels rapidly and accurately. The study uses Ulmus pumila leaves infected by Tetraneura akinire Sasaki at different stages as materials; after extraction with 80% methanol and ethyl acetate and purification with primary secondary amine (PSA) and graphitized carbon blacks (GCB), the contents of signal compounds salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate were determined by GC-MS. The results showed that the level of salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate increased remarkably in U. pumila once infected by T. akinire Sasaki, but the maximums of these four compounds occurred at different times. Salicylic acid level reached the highest at the early stage, and jasmonic acid level went to the maximum in the middle stage; by contrast, change of content of methyl salicylate and methyl jasmonate was the quite opposite. PMID:26457083

  15. DNA Methylation

    PubMed Central

    Marinus, M.G.; Løbner-Olesen, A.

    2014-01-01

    The DNA of E. coli contains 19,120 6-methyladenines and 12,045 5-methylcytosines in addition to the four regular bases and these are formed by the postreplicative action of three DNA methyltransferases. The majority of the methylated bases are formed by the Dam and Dcm methyltransferases encoded by the dam (DNA adenine methyltransferase) and dcm (DNA cytosine methyltransferase) genes. Although not essential, Dam methylation is important for strand discrimination during repair of replication errors, controlling the frequency of initiation of chromosome replication at oriC, and regulation of transcription initiation at promoters containing GATC sequences. In contrast, there is no known function for Dcm methylation although Dcm recognition sites constitute sequence motifs for Very Short Patch repair of T/G base mismatches. In certain bacteria (e.g., Vibrio cholerae, Caulobacter crescentus) adenine methylation is essential and in C. crescentus, it is important for temporal gene expression which, in turn, is required for coordinating chromosome initiation, replication and division. In practical terms, Dam and Dcm methylation can inhibit restriction enzyme cleavage; decrease transformation frequency in certain bacteria; decrease the stability of short direct repeats; are necessary for site-directed mutagenesis; and to probe eukaryotic structure and function. PMID:26442938

  16. Methyl chloride

    Integrated Risk Information System (IRIS)

    Methyl chloride ; CASRN 74 - 87 - 3 ( 07 / 17 / 2001 ) Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for

  17. Methyl acrylate

    Integrated Risk Information System (IRIS)

    Methyl acrylate ; CASRN 96 - 33 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  18. Methyl isocyanate

    Integrated Risk Information System (IRIS)

    Methyl isocyanate ; CASRN 624 - 83 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  19. Methyl iodide

    Integrated Risk Information System (IRIS)

    Methyl iodide ; CASRN 74 - 88 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effe

  20. Methyl parathion

    Integrated Risk Information System (IRIS)

    Methyl parathion ; CASRN 298 - 00 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  1. Methyl chlorocarbonate

    Integrated Risk Information System (IRIS)

    Methyl chlorocarbonate ; CASRN 79 - 22 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  2. Methyl methacrylate

    Integrated Risk Information System (IRIS)

    Methyl methacrylate ; CASRN 80 - 62 - 6 ( 03 / 02 / 98 ) Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments f

  3. Perspectives for the biotechnological production of ethyl acetate by yeasts.

    PubMed

    Löser, Christian; Urit, Thanet; Bley, Thomas

    2014-06-01

    Ethyl acetate is an environmentally friendly solvent with many industrial applications. The production of ethyl acetate currently proceeds by energy-intensive petrochemical processes which are based on natural gas and crude oil without exception. Microbial synthesis of ethyl acetate could become an interesting alternative. The formation of esters as aroma compounds in food has been repeatedly reviewed, but a survey which deals with microbial synthesis of ethyl acetate as a bulk product is missing. The ability of yeasts for producing larger amounts of this ester is known for a long time. In the past, this potential was mainly of scientific interest, but in the future, it could be applied to large-scale ester production from renewable raw materials. Pichia anomala, Candida utilis, and Kluyveromyces marxianus are yeasts which convert sugar into ethyl acetate with a high yield where the latter is the most promising one. Special attention was paid to the mechanism of ester synthesis including regulatory aspects and to the maximum and expectable yield. Synthesis of much ethyl acetate requires oxygen which is usually supplied by aeration. Ethyl acetate is highly volatile so that aeration results in its phase transfer and stripping. This stripping process cannot be avoided but requires adequate handling during experimentation and offers a chance for a cost-efficient process-integrated recovery of the synthesized ester. PMID:24788328

  4. Origins of enigmatic C-3 methyl and C-3 H porphyrins in ancient sediments revealed from formation of pyrophaeophorbide d in simulation experiments

    NASA Astrophysics Data System (ADS)

    Pickering, Matthew D.; Keely, Brendan J.

    2013-03-01

    The reaction of methyl pyrophaeophorbide a with hydrogen sulfide and oxygen under mild conditions (low temperature, moderate pH), which resemble those in certain natural environments, leads to its near quantitative conversion into methyl pyrophaeophorbide d (82-89%). The transformation, via oxidative cleavage of the C-3 vinyl substituent of pyrophaeophorbide a to afford an aldehyde at C-3, results from co-oxidation of the vinyl group and hydrogen sulfide by molecular oxygen. The co-oxidation transformation pathway operating on vinyl substituted chlorophyll derivatives can explain the origins of C-3 methyl and C-3 H porphyrins in ancient sediments and oils, structures for which the origins were previously unresolved. Evaluation of previous reports of C-3 methyl and C-3 H porphyrins in ancient sediments and oils reveals that their distributions are consistent with insights provided from analysis of the reaction mechanisms revealed by the laboratory studies. Thus, the sedimentary distributions reveal key features of the depositional settings, in particular the presence of a deep or a shallow chemocline. The oxidative cleavage of the C-3 vinyl group also provides insight into the biosynthesis of chlorophyll d by the cyanobacterium Acaryochloris marina, and offers a mild alternative to classical methods for the synthetic manipulation of the vinyl substituents of tetrapyrroles.

  5. DIETARY SELENIUIM (SE) AND FOLATE AFFECT DIMETHYLHYDRAZINE (DMH)-INDUCED ABERRANT CRYPT FORMATION, GLOBAL DNA METHYLATION AND ONE-CARBON METABOLISM IN RATS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several observations implicate a role for DNA methylation in cancer pathogenesis. Although both Se and folate deficiency have been shown to cause global DNA hypomethylation and increased cancer susceptibility, the nutrients have different effects on one-carbon metabolism. Thus, the purpose of this s...

  6. Influence of manufacturing conditions and crop season on the formation of 4-mercapto-4-methyl-2-pentanone in Japanese green tea (sen-cha).

    PubMed

    Kumazawa, Kenji; Kubota, Kikue; Masuda, Hideki

    2005-06-29

    4-Mercapto-4-methyl-2-pentanone is one of the most strongly contributing odorants in the volatile fraction of a Japanese green tea (sen-cha) infusion, and on the basis of the results of an aroma extract dilution analysis, the contribution of this compound to the flavor of the sen-cha infusion varied according to the degree of heating of the tea leaves during the roasting process. The concentration of this odorant in the sen-cha infusion, as with other roasty odorants, increased with the increasing roasting temperature. However, the slope of the increase curve differed with the odor compound, and even if roasting was done at a low temperature, at which the other roasty odorants hardly increased, 4-mercapto-4-methyl-2-pentanone still increased and reached a maximum at 112 degrees C. On the other hand, the amount of 4-mercapto-4-methyl-2-pentanone in sen-cha was a maximum in the first crop, then decreasing in the order of the second and third crops. These results suggested that the amount of 4-mercapto-4-methyl-2-pentanone was closely involved with the quality of sen-cha and that the concentration was dependent on the roasting conditions for the green tea leaves, which might be accompanied by an enzymatic reaction. PMID:15969524

  7. The origins of atmospheric methyl mercury

    SciTech Connect

    Prestbo, E.M.; Bloom, N.S.

    1995-12-31

    Methyl Hg in precipitation shows strong regional patterns, with highest volume weighted mean values (0.4 ng/L) in the Pacific Northwest and lowest values in Florida (<0.01 ng/l). Over most of the North Central region, average values range from 0.05 to 0.2 ng/L. Several potential sources of methyl Hg to the atmosphere have been investigated, including direct anthropogenic emissions, atmospheric methylation of Hg{sup o} or Hg(II), and emissions of methyl or dimethyl Hg from natural surfaces (oceans, bogs, or forests). Direct measurements of major total Hg sources such as coal and waste combustors, and sewage treatment facilities suggest that direct anthropogenic emissions are an insignificant source of methyl Hg to the atmosphere. The gas phase reaction of methyl halides with Hg{sup o} also appears to be an insignificant source of methyl Hg to the atmosphere. Recent laboratory experiments have provided a likely mechanism for atmospheric Hg methylation via a complex reaction involving acetate, sulfite, and iron. From a series of field measurements, another source appears to be the degradation of dimethyl mercury emitted by the upwelling of deep ocean water.

  8. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  9. Vinyl ethers containing an epoxy group. XVI. Reaction of glycidol vinyloxyethyl ether with acetals

    SciTech Connect

    Nedolya, N.A.; Khil'ko, M.Ya.; Trofimov, B.A.; Sigalov, M.V.

    1988-10-10

    In order to obtain branched acetals with epoxide groups (prospective monomers and intermediates) the authors investigated the reaction of acetaldehyde diethyl and di(1,1,3-trihydrotetrafluoropropyl) acetals with glycidol vinyloxyethyl ether. The addition of acetals to vinyl epoxy ethers was realized, and the first representative of compounds of this type, i.e., 9-glycidyloxy-6-ethoxy-4-methyl-3,7-dioxanonane, was obtained. It was also impossible to add a fluoroacetal to butyl vinyl ether (0.08-1.00 wt. % of catalyst CF/sub 3/COOH, BF/sub 3//times/ OEt/sub 2/, 20-80/degree/C, 0.5-3 h).

  10. Fragrance material review on 2-(p-tolyloxy)ethyl acetate.

    PubMed

    McGinty, D; Letizia, C S; Api, A M

    2012-09-01

    A toxicologic and dermatologic review of 2-(p-tolyloxy)ethyl acetate when used as a fragrance ingredient is presented. 2-(p-tolyloxy)ethyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 2-(p-tolyloxy)ethyl acetate were evaluated, then summarized, and includes physical properties data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414652

  11. (14C)acetate assimilation by a type I obligate methylotroph, Methylococcus capsulatus.

    PubMed Central

    Patel, R N; Hoare, S L; Hoare, D S; Taylor, B F

    1977-01-01

    Methanol and formate oxidation supported the assimilation of [14C]acetate by cell suspensions of Methylococcus capsulatus; oxidation of other primary alcohols, except ethanol, did not. The extent of [1-14C]acetate assimilation supported by methanol oxidation was decreased in the presence of primary alcohols, except ethanol. Potassium cyanide (0.33 mM) completely inhibited the oxidation of formate and its stimulation of [1-14C]acetate assimilation. The amount of [1-14C]acetate assimilation supported by methanol oxidation was significantly inhibited by cyanide. PMID:412469

  12. ARSENIC (+3 OXIDATION STATE) METHYLTRANSFERASE AND THE METHYLATION OF ARSENICALS

    EPA Science Inventory

    Metabolic conversion of inorganic arsenic into methylated products is a multistep process that yields mono, di, and trimethylated arsenicals. In recent years, it has become apparent that formation of methylated metabolites of inorganic arsenic is not necessarily a detoxification...

  13. Antibiofilm Properties of Acetic Acid

    PubMed Central

    Bjarnsholt, Thomas; Alhede, Morten; Jensen, Peter Østrup; Nielsen, Anne K.; Johansen, Helle Krogh; Homøe, Preben; Høiby, Niels; Givskov, Michael; Kirketerp-Møller, Klaus

    2015-01-01

    Bacterial biofilms are known to be extremely tolerant toward antibiotics and other antimicrobial agents. These biofilms cause the persistence of chronic infections. Since antibiotics rarely resolve these infections, the only effective treatment of chronic infections is surgical removal of the infected implant, tissue, or organ and thereby the biofilm. Acetic acid is known for its antimicrobial effect on bacteria in general, but has never been thoroughly tested for its efficacy against bacterial biofilms. In this article, we describe complete eradication of both Gram-positive and Gram-negative biofilms using acetic acid both as a liquid and as a dry salt. In addition, we present our clinical experience of acetic acid treatment of chronic wounds. In conclusion, we here present the first comprehensive in vitro and in vivo testing of acetic acid against bacterial biofilms. PMID:26155378

  14. Protein content and enzyme activities in methanol- and acetate-grown Methanosarcina thermophila.

    PubMed Central

    Jablonski, P E; DiMarco, A A; Bobik, T A; Cabell, M C; Ferry, J G

    1990-01-01

    The cell extract protein content of acetate- and methanol-grown Methanosarcina thermophila TM-1 was examined by two-dimensional polyacrylamide gel electrophoresis. More than 100 mutually exclusive spots were present in acetate- and methanol-grown cells. Spots corresponding to acetate kinase, phosphotransacetylase, and the five subunits of the carbon monoxide dehydrogenase complex were identified in acetate-grown cells. Activities of formylmethanofuran dehydrogenase, formylmethanofuran:tetrahydromethanopterin formyltransferase, 5,10-methenyltetrahydromethanopterin cyclohydrolase, methylene tetrahydromethanopterin:coenzyme F420 oxidoreductase, formate dehydrogenase, and carbonic anhydrase were examined in acetate- and methanol-grown Methanosarcina thermophila. Levels of formyltransferase in either acetate- or methanol-grown Methanosarcina thermophila were approximately half the levels detected in H2-CO2-grown Methanobacterium thermoautotrophicum. All other enzyme activities were significantly lower in acetate- and methanol-grown Methanosarcina thermophila. Images FIG. 1 FIG. 2 PMID:2307649

  15. Synthesis of Saturated Long Chain Fatty Acids from Sodium Acetate-1-C14 by Mycoplasma1

    PubMed Central

    Pollack, J. D.; Tourtellotte, M. E.

    1967-01-01

    Three strains of Mycoplasma, M. laidlawii A and B, and Mycoplasma sp. A60549, were grown in broth containing sodium acetate-1-C14. The methyl esters of the phospholipid fatty acids of harvested radioactive cells were prepared and identified by comparison of their mobilities to known radioactive fatty acid methyl esters by use of a modified reversed-phase partition-thin layer chromatographic technique. No radioactive methyl oleate or methyl linoleate was detected. Compounds migrating as radioactive methyl myristate, stearate, palmitate, and, with less certainty, laurate and octanoate were detected. The qualitative findings for all three organisms appeared similar. M. laidlawii B synthesized a radioactive substance, presumably a saturated fatty acid detected as the methyl ester derivative, which migrated in a position intermediate to methyl myristate-1-C14 and methyl palmitate-1-C14. This work indicates that M. laidlawii A and B and Mycoplasma sp. A60549 are capable, in a complex medium containing fatty acids, of synthesizing saturated but not unsaturated fatty acids entirely or in part from acetate. Images PMID:6020566

  16. Quadruplex formation by both G-rich and C-rich DNA strands of the C9orf72 (GGGGCC)8•(GGCCCC)8 repeat: effect of CpG methylation

    PubMed Central

    Zamiri, Bita; Mirceta, Mila; Bomsztyk, Karol; Macgregor, Robert B.; Pearson, Christopher E.

    2015-01-01

    Unusual DNA/RNA structures of the C9orf72 repeat may participate in repeat expansions or pathogenesis of amyotrophic lateral sclerosis and frontotemporal dementia. Expanded repeats are CpG methylated with unknown consequences. Typically, quadruplex structures form by G-rich but not complementary C-rich strands. Using CD, UV and electrophoresis, we characterized the structures formed by (GGGGCC)8 and (GGCCCC)8 strands with and without 5-methylcytosine (5mCpG) or 5-hydroxymethylcytosine (5hmCpG) methylation. All strands formed heterogenous mixtures of structures, with features of quadruplexes (at pH 7.5, in K+, Na+ or Li+), but no feature typical of i-motifs. C-rich strands formed quadruplexes, likely stabilized by G•C•G•C-tetrads and C•C•C•C-tetrads. Unlike G•G•G•G-tetrads, some G•C•G•C-tetrad conformations do not require the N7-Guanine position, hence C9orf72 quadruplexes still formed when N7-deazaGuanine replace all Guanines. 5mCpG and 5hmCpG increased and decreased the thermal stability of these structures. hnRNPK, through band-shift analysis, bound C-rich but not G-rich strands, with a binding preference of unmethylated > 5hmCpG > 5mCpG, where methylated DNA-protein complexes were retained in the wells, distinct from unmethylated complexes. Our findings suggest that for C-rich sequences interspersed with G-residues, one must consider quadruplex formation and that methylation of quadruplexes may affect epigenetic processes. PMID:26432832

  17. Quadruplex formation by both G-rich and C-rich DNA strands of the C9orf72 (GGGGCC)8•(GGCCCC)8 repeat: effect of CpG methylation.

    PubMed

    Zamiri, Bita; Mirceta, Mila; Bomsztyk, Karol; Macgregor, Robert B; Pearson, Christopher E

    2015-11-16

    Unusual DNA/RNA structures of the C9orf72 repeat may participate in repeat expansions or pathogenesis of amyotrophic lateral sclerosis and frontotemporal dementia. Expanded repeats are CpG methylated with unknown consequences. Typically, quadruplex structures form by G-rich but not complementary C-rich strands. Using CD, UV and electrophoresis, we characterized the structures formed by (GGGGCC)8 and (GGCCCC)8 strands with and without 5-methylcytosine (5mCpG) or 5-hydroxymethylcytosine (5hmCpG) methylation. All strands formed heterogenous mixtures of structures, with features of quadruplexes (at pH 7.5, in K(+), Na(+) or Li(+)), but no feature typical of i-motifs. C-rich strands formed quadruplexes, likely stabilized by G•C•G•C-tetrads and C•C•C•C-tetrads. Unlike G•G•G•G-tetrads, some G•C•G•C-tetrad conformations do not require the N7-Guanine position, hence C9orf72 quadruplexes still formed when N7-deazaGuanine replace all Guanines. 5mCpG and 5hmCpG increased and decreased the thermal stability of these structures. hnRNPK, through band-shift analysis, bound C-rich but not G-rich strands, with a binding preference of unmethylated > 5hmCpG > 5mCpG, where methylated DNA-protein complexes were retained in the wells, distinct from unmethylated complexes. Our findings suggest that for C-rich sequences interspersed with G-residues, one must consider quadruplex formation and that methylation of quadruplexes may affect epigenetic processes. PMID:26432832

  18. Systematic analysis of O-methyltransferase gene family and identification of potential members involved in the formation of O-methylated flavonoids in Citrus.

    PubMed

    Liu, Xiaogang; Luo, Yan; Wu, Hongkun; Xi, Wanpeng; Yu, Jie; Zhang, Qiuyun; Zhou, Zhiqin

    2016-01-10

    The O-methylation of various secondary metabolites is mainly catalyzed by S-adenosyl-l-methionine (SAM)-dependent O-methyltransferase (OMT) proteins that are encoded by the O-methyltransferase gene family. Citrus fruits are a rich source of O-methylated flavonoids that have a broad spectrum of biological activities, including anti-inflammatory, anticarcinogenic, and antiatherogenic properties. However, little is known about this gene family and its members that are involved in the O-methylation of flavonoids and their regulation in Citrus. In this study, 58 OMT genes were identified from the entire Citrus sinensis genome and compared with those from 3 other representative dicot plants. A comprehensive analysis was performed, including functional/substrate predictions, identification of chromosomal locations, phylogenetic relationships, gene structures, and conserved motifs. Distribution mapping revealed that the 58 OMT genes were unevenly distributed on the 9 citrus chromosomes. Phylogenetic analysis of 164 OMT proteins from C.sinensis, Arabidopsis thaliana, Populus trichocarpa, and Vitis vinifera showed that these proteins were categorized into group I (COMT subfamily) and group II (CCoAOMT subfamily), which were further divided into 10 and 2 subgroups, respectively. Finally, digital gene expression and quantitative real-time polymerase chain reaction analyses revealed that citrus OMT genes had distinct temporal and spatial expression patterns in different tissues and developmental stages. Interestingly, 18 and 11 of the 27 genes predicted to be involved in O-methylation of flavonoids had higher expression in the peel and pulp during fruit development, respectively. The citrus OMT gene family identified in this study might help in the selection of appropriate candidate genes and facilitate functional studies in Citrus. PMID:26407870

  19. Lung cancer-associated JmjC domain protein mdig suppresses formation of tri-methyl lysine 9 of histone H3.

    PubMed

    Lu, Yongju; Chang, Qingshan; Zhang, Yadong; Beezhold, Kevin; Rojanasakul, Yon; Zhao, Hongwen; Castranova, Vince; Shi, Xianglin; Chen, Fei

    2009-07-01

    Lung cancer is the most common cancer worldwide, accounting for 1.3 million cancer deaths annually. Despite extensive studies over the past decade, the detailed mechanism about the initiation and development of the lung cancer is still elusive. In the present report, we showed that overexpression of mdig is a common feature of the non-small cell lung cancer. Gene silencing or overexpression of mdig revealed that mdig is involved in demethylation of tri-methyl lysine 9 on histone H3, leading to an increase in ribosomal RNA expression. The transcriptional regulation of ribosomal RNA gene by mdig is achieved through abrogating tri-methyl lysine 9 on histone H3 and enhancing RNA polymerase I occupancy in the promoter region of the ribosomal RNA gene as demonstrated by chromatin immunoprecipitation. The pronounced expression of mdig in lung cancer tissues but not normal lung tissues, thus, suggests that mdig possesses oncogenic property through antagonizing tri-methyl lysine 9 on histone H3 and promoting ribosomal RNA synthesis. PMID:19502796

  20. Intrinsic Hydration of Uranyl-Hydroxide, -Nitrate and -Acetate Complexes

    SciTech Connect

    Winnie Chien; Dorothy Hanna; Victor Anbalagan; Garold Gresham; Gary Groenewold; Michael Van Stipdonk

    2004-06-01

    The intrinsic hydration of three monopositive uranyl-anion complexes (UO2A)+ (where A = acetate, nitrate, or hydroxide) was investigated using ion-trap mass spectrometry (IT-MS). The relative rates for the formation of the monohydrates [(UO2A)(H2O)]+, with respect to the anion, followed the trend: Acetate = nitrate >> hydroxide. This finding was rationalized in terms of the donation of electron density by the strongly basic OH- to the uranyl metal center, thereby reducing the Lewis acidity of U and its propensity to react with incoming nucleophiles, viz., H2O. An alternative explanation is that the more complex acetate and nitrate anions provide increased degrees of freedom that could accommodate excess energy from the hydration reaction. The monohydrates also reacted with water, forming dihydrates and then trihydrates. The rates for formation of the nitrate and acetate dihydrates [(UO2A)(H2O)2]+ were very similar to the rates for formation of the monohydrates; the presence of the first H2O ligand had no influence on the addition of the second. In contrast, formation of the [(UO2OH)(H2O)2]+ was nearly three times faster than the formation of the monohydrate.

  1. Method for determination of methyl tert-butyl ether and its degradation products in water

    USGS Publications Warehouse

    Church, C.D.; Isabelle, L.M.; Pankow, J.F.; Rose, D.L.; Tratnyek, P.G.

    1997-01-01

    An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method can also give simultaneous identification of polar compounds that might occur as degradation products of gasoline oxygenates, such as TBA, TBF, TAA, methyl acetate, and acetone. When the method was applied to effluent from a column microcosm prepared with core material from an urban site in New Jersey, conversion of MTBE to TBA was observed after a lag period of 35 days. However, to date, analyses of water samples from six field sites using the DAI-GC/MS method have not produced evidence for the expected products of in situ degradation of MTBE.An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method

  2. Mercury Methylation in Alaskan Peatlands Spanning a Large Range of Trophic Structure

    NASA Astrophysics Data System (ADS)

    Krabbenhoft, D. P.; Zhang, L.; Hines, M. E.; Barkay, T.; Schaefer, J.; Aiken, G.

    2015-12-01

    The process of mercury (Hg) methylation has long been recognized as a key area of research in order to understand spatial and temporal variability of toxic methylmercury (MeHg) on the landscape. Numerous factors affect MeHg production, the most important generally falling into those that affect inorganic Hg(II) bioavailability (e.g., Hg(II) concentration and ligand composition), and those that affect microbial community composition and activity. The principal goal of this project is to decipher the details of MeHg production in Alaskan peatlands exhibiting a range of trophic status, including those lacking in electron acceptors that support the traditional respiratory pathway of MeHg production (e.g., sulfate reduction). MeHg production is carried out by a diverse group of microorganisms that possess the gene cluster (hgcAB), including the well-studied sulfate and iron- reducing bacteria (SRB and FeRB). However, less well known bacteria also possess the hgcAB genes, including: syntrophs, methanogens, acetogens, and fermenters. Methylation and demethylation activities were determined by injecting trace levels of the stable isotope (198Hg and Me204Hg) into intact peat cores. In addition, the short-lived radioisotope 197Hg was used in laboratory incubations. Laboratory studies also included assays for changes in diagnostic gas concentrations (CH4, CO2, H2) and LMW organic acids (formate, acetate, propionate, butyrate) to infer specific microbial processes, and the use of genomics to confirm microbial assemblages and the presence/absence of hgcAB genes. Overall, we observed Hg methylation rates were greatest at minerotrophic sites with active syntrophy and methanogenesis. Methylation and demethylation rates corresponded significantly across sites. There was no evidence of SO4- reduction in these samples, and addition of SO4- did not stimulate methylation suggesting that methylation was conducted by SRB that were metabolizing syntrophically and/or by fermentation.

  3. Methyl-coenzyme M, an intermediate in methanogenic dissimilation of C/sub 1/ compounds by Methanosarcina barkeri

    SciTech Connect

    Shapiro, S.; Wolfe, R.S.

    1980-02-01

    Extracts of Methanosarcina barkeri possess a specific methyltransferase that catalyzes the transfer of the methyl group of methanol to 2-mercaptoethanesulfonic acid. Over a fourfold range in added 2-mercaptoethanesulfonic acid, the formation of 2-(methylthio)ethanesulfonic acid exhibited a 1:1 ratio to 2-mercaptoethanesulfonic acid added. This reaction required adenosine 5'-triphosphate; a maximal ratio (mole/mol) of 85 methyl groups was transferred per adenosine 5'-triphosphate added. The methyltransferase was found in extracts of methanol-grown cells as well as in extracts of hydrogen-grown cells. In extracts of cells grown on either substrate, 2-(methylthio)ethanesulfonic acid was formed from added methanol or methylamine but not from acetate.

  4. Rapid and sensitive LC-MS/MS method for determination of megestrol acetate in human plasma: application to a human pharmacokinetic study.

    PubMed

    Seo, Ji-Hyung; Park, Ji-Sun; Jo, Min-Ho; Park, Mi-Sun; Ryu, Ju-Hee; Cho, Young-Wuk; Shim, Wang-Sup; Noh, Gyu-Jeong; Lee, Kyung-Tae

    2013-04-01

    A rapid, simple and fully validated LC-MS/MS method was developed and validated for the determination of megestrol acetate in human plasma using tolbutamide as an internal standard (IS) after one-step liquid-liquid extraction with methyl-tert-butyl-ether. Detection was performed using electrospray ionization in positive ion multiple reaction monitoring mode by monitoring the transitions m/z 385.5 → 267.1 for megestrol acetate and m/z 271.4 → 155.1 for IS. Chromatographic separation was performed on a YMC Hydrosphere C18 column with an isocratic mobile phase, which consisted of 10 mm ammonium formate buffer (adjusted to pH 5.0 with formic acid)-methanol (60:40, v/v) at a flow rate of 0.4 mL/min. The achieved lower limit of quantitation (LLOQ) was 1 ng/mL (signal-to-noise ratio > 10) and the standard calibration curve for megestrol acetate was linear (r > 0.99) over the studied concentration range (1-2000 ng/mL). The proposed method was fully validated by determining its specificity, linearity, LLOQ, intra- and inter-day precision and accuracy, recovery, matrix effect and stability. The validated LC-MS/MS method was successfully applied for the evaluation of pharmacokinetic parameters of megestrol acetate after oral administration of a single dose 800 mg of megestrol acetate (Megace™) to five healthy Korean male volunteers under fed conditions. PMID:22961730

  5. Methyl gallate.

    PubMed

    Bebout, Deborah; Pagola, Silvina

    2009-01-01

    THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND (SYSTEMATIC NAME: methyl 3,4,5-trihydroxy-benzoate), C(8)H(8)O(5), is composed of essentially planar mol-ecules [maximum departures from the mean carbon and oxygen skeleton plane of 0.0348 (10) Å]. The H atoms of the three hydroxyl groups, which function as hydrogen-bond donors and acceptors simultaneously, are oriented in the same direction around the aromatic ring. In addition to two intra-molecular hydrogen bonds, each mol-ecule is hydrogen bonded to six others, creating a three-dimensional hydrogen-bonded network. PMID:21581923

  6. Methyl gallate

    PubMed Central

    Bebout, Deborah; Pagola, Silvina

    2009-01-01

    The crystal structure of the title compound (systematic name: methyl 3,4,5-trihydroxy­benzoate), C8H8O5, is composed of essentially planar mol­ecules [maximum departures from the mean carbon and oxygen skeleton plane of 0.0348 (10) Å]. The H atoms of the three hydroxyl groups, which function as hydrogen-bond donors and acceptors simultaneously, are oriented in the same direction around the aromatic ring. In addition to two intra­molecular hydrogen bonds, each mol­ecule is hydrogen bonded to six others, creating a three-dimensional hydrogen-bonded network. PMID:21581923

  7. The biochemical pathway for the breakdown of methyl cyanide (acetonitrile) in bacteria.

    PubMed Central

    Firmin, J L; Gray, D O

    1976-01-01

    [2-14C]Methyl cyanide (acetonitrile) is metabolized to citrate, succinate, fumarate, malate, glutamate, pyrrolidonecarboxylic acid and aspartate. Non-radioactive acetamide and acetate compete with 14C from methyl cyanide, and [2-14C]acetate and [2-14C]methyl cyanide are metabolized at similar rates, giving identical products. This evidence, combined with the inhibitory effect of fluoroacetate and arsenite on methyl cyanide metabolism, indicates that the pathway is: methyl cyanide leads to acetamide leads to acetate leads to tricarboxylic acid-cycle intermediates. The pathway was investigated in a species of Pseudomonas (group III; N.C.I.B. 10477), but comparison of labelling patterns suggests that it also exists in several higher plants. PMID:985423

  8. The carbon isotope biogeochemistry of acetate from a methanogenic marine sediment

    NASA Technical Reports Server (NTRS)

    Blair, N. E.; Carter, W. D., Jr.

    1992-01-01

    The delta C-13 value of porewater acetate isolated from the anoxic sediments of Cape Lookout Bight (North Carolina) ranged from -17.6 percent in the sulfate reduction zone to -2.8 percent in the underlying methanogenic zone. The large C-13 enrichment in the sulfate-depleted sediments appears to be associated with the dissimilation of acetate to CH4 and CO2. Fractionation factors for that process were estimated to be 1.032 +/- 0.014 and 1.036 +/- 0.019 for the methyl and carboxyl groups. A subsurface maximum in delta C-13 of the total acetate molecule, as well as the methyl and carboxyl carbons at 10-15 cm depth within the sediment column, indicate that changes in the relative rates of acetate cycling pathways occur in the methanogenic zone. The methyl group of the acetate was depleted in C-13 by 7-14 percent relative to the carboxyl moiety. The intramolecular heterogeneity may be the result of both synthetic and catabolic isotope effects.

  9. Determination of Unknown Concentrations of Sodium Acetate Using the Method of Standard Addition and Proton NMR: An Experiment for the Undergraduate Analytical Chemistry Laboratory

    ERIC Educational Resources Information Center

    Rajabzadeh, Massy

    2012-01-01

    In this experiment, students learn how to find the unknown concentration of sodium acetate using both the graphical treatment of standard addition and the standard addition equation. In the graphical treatment of standard addition, the peak area of the methyl peak in each of the sodium acetate standard solutions is found by integration using…

  10. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium acetate. 184.1185 Section 184.1185 Food and... Substances Affirmed as GRAS § 184.1185 Calcium acetate. (a) Calcium acetate (Ca (C2H3O2)2, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may...

  11. Dissimilation of Carbon Monoxide to Acetic Acid by Glucose-Limited Cultures of Clostridium thermoaceticum

    PubMed Central

    Martin, Douglas R.; Misra, Arun; Drake, Harold L.

    1985-01-01

    Clostridium thermoaceticum was cultivated in glucose-limited media, and the dissimilation of CO to acetic acid was evaluated. We found that cultures catalyzed the rapid dissimilation of CO to acetic acid and CO2, with the stoichiometry obtained for conversion approximating that predicted from the following reaction: 4CO + 2H2O → CH3CO2H + 2CO2. Growing cultures formed approximately 50 mmol (3 g) of CO-derived acetic acid per liter of culture, with the rate of maximal consumption approximating 9.1 mmol of CO consumed/h per liter of culture. In contrast, resting cells were found not to dissimilate CO to acetic acid. 14CO was incorporated, with equal distribution between the carboxyl and methyl carbons of acetic acid when the initial cultivation gas phase was 100% CO, whereas 14CO2 preferentially entered the carboxyl carbon when the initial gas phase was 100% CO2. Significantly, in the presence of saturating levels of CO, 14CO2 preferentially entered the methyl carbon, whereas saturating levels of CO2 yielded 14CO-derived labeling predominantly in the carboxyl carbon. These findings are discussed in relation to the path of carbon flow to acetic acid. PMID:16346807

  12. Effects of antioxidants of bamboo leaves and flavonoids on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation in chemical model systems.

    PubMed

    Zhang, Yan; Luo, Zhou; Shao, Zeping; Yu, Chundi; Wang, Shuo

    2014-05-21

    The inhibitory effects of antioxidants of bamboo leaves (AOB) and flavonoids against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation were investigated in creatinine and phenylalanine model systems. AOB and the tested flavonoids (orientin, homoorientin, vitexin, isovitex, apigenin, luteolin, isorhamnetin, fisetin, and hesperetin) had significant dose-dependent inhibition effects on PhIP formation with different IC50 values. The superoxide anion (O2(•-)) scavenging activities of these nine flavonoids were evaluated using the pyrogallol autoxidation system. The EC50 values of compounds that showed antioxidant activity were found to correlate well (R(2) = 0.8003) with the corresponding IC50 values representing their inhibition of PhIP formation. It was assumed that the inhibitory effects of flavonoids on PhIP formation were probably achieved by scavenging free radicals generated in the reaction system. These findings provide valuable information for the development of effective strategies to minimize heterocyclic amine content in thermally processed food. PMID:24806809

  13. Transmethylation reactions during methanogenesis from acetate in Methanosarcina barkeri. [Annual report], August 1, 1991--April 1, 1993

    SciTech Connect

    Krzycki, J.A.

    1993-07-01

    Methanosarcina possesses an abundance corrinoid, which acts as enzyme prosthetic group and functions in methyl transfer reactions. When this work was initiated only two corrinoid proteins had been described from Methanosarcina: methyltransferase I, which catalyses the first step m methanogenesis from methanol; and the corrinoid/iron sulfur protein, which is the primary methyl accepting group in the cleavage of acetyl-CoA during methanogenesis from acetate. Using our technique of in vitro methylation of corrinoid proteins by radioactive methanogenic substrates we have found several novel corrinoid proteins are present in this organism which can function as methytransferases, which are methylated by growth substrate, and are apparently regulated by growth substrate.

  14. Microbial process for the preparation of acetic acid, as well as solvent for its extraction from the fermentation broth

    DOEpatents

    Gaddy, James L.; Clausen, Edgar C.; Ko, Ching-Whan; Wade, Leslie E.; Wikstrom, Carl V.

    2004-06-22

    A modified water-immiscible solvent useful in the extraction of acetic acid from aqueous streams is a substantially pure mixture of isomers of highly branched di-alkyl amines. Solvent mixtures formed of such a modified solvent with a desired co-solvent, preferably a low boiling hydrocarbon, are useful in the extraction of acetic acid from aqueous gaseous streams. An anaerobic microbial fermentation process for the production of acetic acid employs such solvents, under conditions which limit amide formation by the solvent and thus increase the efficiency of acetic acid recovery. Methods for the direct extraction of acetic acid and the extractive fermentation of acetic acid also employ the modified solvents and increase efficiency of acetic acid production. Such increases in efficiency are also obtained where the energy source for the microbial fermentation contains carbon dioxide and the method includes a carbon dioxide stripping step prior to extraction of acetic acid in solvent.

  15. Microbial process for the preparation of acetic acid, as well as solvent for its extraction from the fermentation broth

    DOEpatents

    Gaddy, James L.; Clausen, Edgar C.; Ko, Ching-Whan; Wade, Leslie E.; Wikstrom, Carl V.

    2007-03-27

    A modified water-immiscible solvent useful in the extraction of acetic acid from aqueous streams is a substantially pure mixture of isomers of highly branched di-alkyl amines. Solvent mixtures formed of such a modified solvent with a desired co-solvent, preferably a low boiling hydrocarbon, are useful in the extraction of acetic acid from aqueous gaseous streams. An anaerobic microbial fermentation process for the production of acetic acid employs such solvents, under conditions which limit amide formation by the solvent and thus increase the efficiency of acetic acid recovery. Methods for the direct extraction of acetic acid and the extractive fermentation of acetic acid also employ the modified solvents and increase efficiency of acetic acid production. Such increases in efficiency are also obtained where the energy source for the microbial fermentation contains carbon dioxide and the method includes a carbon dioxide stripping step prior to extraction of acetic acid in solvent.

  16. Methylations of adenosine residues (m6A) in pre-mRNA are important for formation of late simian virus 40 mRNAs.

    PubMed

    Finkel, D; Groner, Y

    1983-12-01

    Cycloleucine, a competitive inhibitor of methionine transferase was used to generate in vivo partially methylated mRNA in SV40-infected BSC-1 cells. Cycloleucine at 0.5 mg/ml causes more than a 30% decrease in internal m6As of late SV40 mRNA with only minor effect on the dimethyladenosine of the 5' caps m7GpppmAm. After treatment with 2 and 5 mg/ml of cycloleucine, internal m6As were reduced by 10- and 100-fold, respectively. The inhibition of BSC-1 mRNA methylations paralleled that observed for late SV40 mRNAs. In cells exposed to 2 mg/ml cycloleucine production of late SV40 mRNA was inhibited by 80% whereas the amount of SV40 nuclear RNA was only slightly reduced. Size fractionation of SV40 nuclear RNA from cycloleucine-treated cells revealed a loss of SV40 19 S RNA with a corresponding increase of fragmented RNA sedimenting between 11 to 5 S, so that the total amount of SV40 RNA in the nucleus was almost unchanged. Analysis of viral transcription complexes from cells treated with cycloleucine indicated that SV40 transcription was not affected by cycloleucine. SV40-transformed cells, in contrast to BSC-1 cells, were able to process and transport undermethylated RNA. When transformed cells were treated with 2 mg/ml cycloleucine no changes in quantities or size of cytoplasmic and nuclear RNA were detected. The data argues for a role of internal m6A moieties in modulating the processing-linked transport of mRNA from the nucleus to the cytoplasm of nontransformed cells. Transformed cells may escape these controls due to structural alterations in their perinuclear regions. PMID:6318439

  17. Methyl allyl ether formation in plants: novel S-adenosyl L-methionine:coniferyl alcohol 9-O-methyltransferase from suspension cultures of three Linum species.

    PubMed

    Berim, Anna; Schneider, Bernd; Petersen, Maike

    2007-06-01

    A novel 41 kDa methyltransferase displaying high regiospecificity towards the allylic hydroxyl moiety of coniferyl alcohol was cloned from suspension cultures of Linum nodiflorum L. and expressed in E. coli. The apparent K (m) for coniferyl alcohol is 7.23 microM with a V (max) of 707.5 pkat mg(-1) protein at 30 degrees C, whereas the K (m) for the co-substrate S-adenosyl-L-methionine is 18.5 microM. Structure-function relationship studies revealed stringent structure requirements. Even minor substructure deviations as the side-chain saturation or changes in the phenyl ring substitution result in activities decreased by 75-90%. Crotyl and allyl alcohols are not substrates, confirming that the aromatic ring itself is indispensable, and solely the derivatives with a C(3) side-chain are accepted. The enzyme shares only similarities under 46% on amino acid level with other known methyltransferases. The designated reaction product, coniferyl alcohol 9-methyl ether, could be detected in suspension cells. The highest content of up to 0.02% of the dry mass is concurrent with an increase of the specific enzyme activity that reaches its maximum of 3.94 pkat mg(-1) on day 6 of the culture period. Transcript levels estimated by semi-quantitative RT-PCR remain constant until day 6 and recede thereafter. The corresponding methyltransferase from Linum flavum L. differs mainly by one short variable fragment. Biochemical characterization revealed a higher catalytic efficiency and a slightly broader substrate plasticity together with a lower sensitivity to the presence of Zn(2+), Cu(2+) and Co(2+). This is to our knowledge the first report of a regiospecific allylic O-methylation of phenylpropanoids in plants. PMID:17333502

  18. Sum-frequency generation of acetate adsorption on Au and Pt surfaces: Molecular structure effects

    NASA Astrophysics Data System (ADS)

    Braunschweig, Björn; Mukherjee, Prabuddha; Kutz, Robert B.; Wieckowski, Andrzej; Dlott, Dana D.

    2010-12-01

    The reversible adsorption of acetate on polycrystalline Au and Pt surfaces was investigated with broadband sum-frequency generation (SFG) and cyclic voltammetry. Specifically adsorbed acetate as well as coadsorbed sulfuric acid anions are observed for the first time with SFG and give rise to dramatically different SFG intensities on Au and Pt surfaces. While similar coverages of acetate adlayers on Au and Pt surfaces are well established by previous studies, an identification of the interfacial molecular structure has been elusive. However, we have applied the high sensitivity of SFG for interfacial polar ordering to identify different acetate structures at Au and Pt surfaces in contact with HClO4 and H2SO4 electrolytes. Acetate competes with the formation of surface oxides and shifts the oxidation threshold of both Au and Pt electrodes anodically. Effects of the supporting electrolyte on the formation of acetate adlayers are revealed by comparing SFG spectra in HClO4 and H2SO4 solutions: Sulfuric acid anions modify the potential-dependent acetate adsorption, compete with adsorbed acetate on Au and coadsorb with acetate on Pt surfaces.

  19. Heterogeneous Reactions of Acetic Acid with Oxide Surfaces: Effects of Mineralogy and Relative Humidity.

    PubMed

    Tang, Mingjin; Larish, Whitney A; Fang, Yuan; Gankanda, Aruni; Grassian, Vicki H

    2016-07-21

    We have investigated the heterogeneous uptake of gaseous acetic acid on different oxides including γ-Al2O3, SiO2, and CaO under a range of relative humidity conditions. Under dry conditions, the uptake of acetic acid leads to the formation of both acetate and molecularly adsorbed acetic acid on γ-Al2O3 and CaO and only molecularly adsorbed acetic acid on SiO2. More importantly, under the conditions of this study, dimers are the major form for molecularly adsorbed acetic acid on all three particle surfaces investigated, even at low acetic acid pressures under which monomers are the dominant species in the gas phase. We have also determined saturation surface coverages for acetic acid adsorption on these three oxides under dry conditions as well as Langmuir adsorption constants in some cases. Kinetic analysis shows that the reaction rate of acetic acid increases by a factor of 3-5 for γ-Al2O3 when relative humidity increases from 0% to 15%, whereas for SiO2 particles, acetic acid and water are found to compete for surface adsorption sites. PMID:27322707

  20. Turning over DNA methylation in the mind

    PubMed Central

    Lister, Ryan; Mukamel, Eran A.

    2015-01-01

    Cytosine DNA methylation is a stable epigenetic modification with established roles in regulating transcription, imprinting, female X-chromosome inactivation, and silencing of transposons. Dynamic gain or loss of DNA methylation reshapes the genomic landscape of cells during early differentiation, and in post-mitotic mammalian brain cells these changes continue to accumulate throughout the phases of cortical maturation in childhood and adolescence. There is also evidence for dynamic changes in the methylation status of specific genomic loci during the encoding of new memories, and these epigenome dynamics could play a causal role in memory formation. However, the mechanisms that may dynamically regulate DNA methylation in neurons during memory formation and expression, and the function of such epigenomic changes in this context, are unclear. Here we discuss the possible roles of DNA methylation in encoding and retrieval of memory. PMID:26283895

  1. Desmopressin Acetate in Intracranial Haemorrhage

    PubMed Central

    Kapapa, Thomas; Röhrer, Stefan; Struve, Sabine; Petscher, Matthias; König, Ralph; Wirtz, Christian Rainer; Woischneck, Dieter

    2014-01-01

    Introduction. The secondary increase in the size of intracranial haematomas as a result of spontaneous haemorrhage or trauma is of particular relevance in the event of prior intake of platelet aggregation inhibitors. We describe the effect of desmopressin acetate as a means of temporarily stabilising the platelet function. Patients and Methods. The platelet function was analysed in 10 patients who had received single (N = 4) or multiple (N = 6) doses of acetylsalicylic acid and 3 patients (control group) who had not taken acetylsalicylic acid. All subjects had suffered intracranial haemorrhage. Analysis was performed before, half an hour and three hours after administration of desmopressin acetate. Statistical analysis was performed by applying a level of significance of P ≤ 0.05. Results. (1) Platelet function returned to normal 30 minutes after administration of desmopressin acetate. (2) The platelet function worsened again after three hours. (3) There were no complications related to electrolytes or fluid balance. Conclusion. Desmopressin acetate can stabilise the platelet function in neurosurgical patients who have received acetylsalicylic acid prior to surgery without causing transfusion-related side effects or a loss of time. The effect is, however, limited and influenced by the frequency of drug intake. Further controls are needed in neurosurgical patients. PMID:25610644

  2. Water radiolysis with heavy ions of energies up to 28 GeV. 3. Measurement of G(MV*+) in deaerated methyl viologen solutions containing various concentrations of sodium formate and Monte Carlo simulation.

    PubMed

    Yamashita, Shinichi; Katsumura, Yosuke; Lin, Mingzhang; Muroya, Yusa; Miyazaki, Toyoaki; Murakami, Takeshi; Meesungnoen, Jintana; Jay-Gerin, Jean-Paul

    2008-10-01

    Formation yields of methyl viologen cation radicals G(MV*+) (100 eV)(-1) have been measured in deaerated aqueous solutions of 0.25 mM methyl viologen (MV(2+)) containing various concentrations of formate anion (0.01-2 M) after irradiation with six different ion beams (4He(2+), 12C(6+), 20Ne(10+), 28Si(14+), 40Ar(18+) and 56Fe(26+) with incident energies varying from 0.6 to 28 GeV) provided by the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Science (NIRS) in Japan. The sample solutions are irradiated at the incident energy of the ions using 1-cm irradiation cells. Corresponding LET values cover the range from 2.2 to 185 eV/nm. G(MV*+) increases with increasing formate concentration. In 4He(2+) radiolysis, it increases from 5.7 to 7.1 as the concentration of formate is increased from 0.01 to 2 M, while in 56Fe(26+) radiolysis, the MV*+ yield value changes from 2.2 to 4.1. The other values lie between the yields for 4He(2+) and 56Fe(26+). In addition, G(MV*+) decreases with increasing LET. In the case of 12C(6+) radiolysis, G(MV*+) increases with increasing energy of the carbon ions from 135 to 400 MeV/nucleon, i.e., with decreasing LET from 21 to 11 eV/nm. In parallel to the above measurements, Monte Carlo simulations of the radiolysis of the MV(2+)/formate solutions have been performed. Ionic strength effects on reactions between charged species are taken into account. To reproduce the experimental results, previously unreported reactions such as e(aq)(-) + MV*+, MV*(+) + *OH and *COO- + *OH have been introduced in the reaction scheme. After optimization, the rate constants of these latter two reactions are determined to be (3 +/- 0.5) x 10(10) and (5 +/- 0.5) x 10(10) M(-1) s(-1), respectively. By contrast, the reaction between e(aq)- and MV*+ is too slow to affect G(MV*+). On the basis of these calculations, characteristics of intratrack reactions induced by heavy-ion beams are discussed in reference not only to the

  3. Cork taint of wines: role of the filamentous fungi isolated from cork in the formation of 2,4,6-trichloroanisole by o methylation of 2,4,6-trichlorophenol.

    PubMed

    Alvarez-Rodríguez, María Luisa; López-Ocaña, Laura; López-Coronado, José Miguel; Rodríguez, Enrique; Martínez, María Jesús; Larriba, Germán; Coque, Juan-José R

    2002-12-01

    Cork taint is a musty or moldy off-odor in wine mainly caused by 2,4,6-trichloroanisole (2,4,6-TCA). We examined the role of 14 fungal strains isolated from cork samples in the production of 2,4,6-TCA by O methylation of 2,4,6-trichlorophenol (2,4,6-TCP). The fungal strains isolated belong to the genera Penicillium (four isolates); Trichoderma (two isolates); and Acremonium, Chrysonilia, Cladosporium, Fusarium, Mortierella, Mucor, Paecilomyces, and Verticillium (one isolate each). Eleven of these strains could produce 2,4,6-TCA when they were grown directly on cork in the presence of 2,4,6-TCP. The highest levels of bioconversion were carried out by the Trichoderma and Fusarium strains. One strain of Trichoderma longibrachiatum could also efficiently produce 2,4,6-TCA in liquid medium. However, no detectable levels of 2,4,6-TCA production by this strain could be detected on cork when putative precursors other than 2,4,6-TCP, including several anisoles, dichlorophenols, trichlorophenols, or other highly chlorinated compounds, were tested. Time course expression studies with liquid cultures showed that the formation of 2,4,6-TCA was not affected by a high concentration of glucose (2% or 111 mM) or by ammonium salts at concentrations up to 60 mM. In T. longibrachiatum the O methylation of 2,4,6-TCP was catalyzed by a mycelium-associated S-adenosyl-L-methionine (SAM)-dependent methyltransferase that was strongly induced by 2,4,6-TCP. The reaction was inhibited by S-adenosyl-L-homocysteine, an inhibitor of SAM-dependent methylation, suggesting that SAM is the natural methyl donor. These findings increase our understanding of the mechanism underlying the origin of 2,4,6-TCA on cork, which is poorly understood despite its great economic importance for the wine industry, and they could also help us improve our knowledge about the biodegradation and detoxification processes associated with chlorinated phenols. PMID:12450804

  4. Cork Taint of Wines: Role of the Filamentous Fungi Isolated from Cork in the Formation of 2,4,6-Trichloroanisole by O Methylation of 2,4,6-Trichlorophenol

    PubMed Central

    Álvarez-Rodríguez, María Luisa; López-Ocaña, Laura; López-Coronado, José Miguel; Rodríguez, Enrique; Martínez, María Jesús; Larriba, Germán; Coque, Juan-José R.

    2002-01-01

    Cork taint is a musty or moldy off-odor in wine mainly caused by 2,4,6-trichloroanisole (2,4,6-TCA). We examined the role of 14 fungal strains isolated from cork samples in the production of 2,4,6-TCA by O methylation of 2,4,6-trichlorophenol (2,4,6-TCP). The fungal strains isolated belong to the genera Penicillium (four isolates); Trichoderma (two isolates); and Acremonium, Chrysonilia, Cladosporium, Fusarium, Mortierella, Mucor, Paecilomyces, and Verticillium (one isolate each). Eleven of these strains could produce 2,4,6-TCA when they were grown directly on cork in the presence of 2,4,6-TCP. The highest levels of bioconversion were carried out by the Trichoderma and Fusarium strains. One strain of Trichoderma longibrachiatum could also efficiently produce 2,4,6-TCA in liquid medium. However, no detectable levels of 2,4,6-TCA production by this strain could be detected on cork when putative precursors other than 2,4,6-TCP, including several anisoles, dichlorophenols, trichlorophenols, or other highly chlorinated compounds, were tested. Time course expression studies with liquid cultures showed that the formation of 2,4,6-TCA was not affected by a high concentration of glucose (2% or 111 mM) or by ammonium salts at concentrations up to 60 mM. In T. longibrachiatum the O methylation of 2,4,6-TCP was catalyzed by a mycelium-associated S-adenosyl-l-methionine (SAM)-dependent methyltransferase that was strongly induced by 2,4,6-TCP. The reaction was inhibited by S-adenosyl-l-homocysteine, an inhibitor of SAM-dependent methylation, suggesting that SAM is the natural methyl donor. These findings increase our understanding of the mechanism underlying the origin of 2,4,6-TCA on cork, which is poorly understood despite its great economic importance for the wine industry, and they could also help us improve our knowledge about the biodegradation and detoxification processes associated with chlorinated phenols. PMID:12450804

  5. Reductive opening of carbohydrate phenylsulfonylethylidene (PSE) acetals.

    PubMed

    Chéry, Florence; Cabianca, Elena; Tatibouët, Arnaud; De Lucchi, Ottorino; Lindhorst, Thisbe K; Rollin, Patrick

    2015-11-19

    The phenylsulfonylethylidene (PSE) acetal is a relatively new protecting group in carbohydrate chemistry. However, carbohydrate-derived phenylsulfonylethylidene (PSE) acetals show a different behavior in reductive desulfonylation than simple symmetrical acetals. Here we have investigated various SET-type reaction conditions in order to open PSE acetals regioselectively and to produce chiral ω-hydroxyethenyl ethers. Whereas sodium amalgam leads to a mixture of regioisomeric vinyl ethers besides the ethylidene acetal, samarium iodide is suited for regioselective ring opening. This is shown with seven different carbohydrate PSE acetals, both of the 1,3-dioxane and the 1,3-dioxolane type. PMID:26469209

  6. CYP2C8- and CYP3A-mediated C-demethylation of (3-{[(4-tert-butylbenzyl)-(pyridine-3-sulfonyl)-amino]-methyl}-phenoxy)-acetic acid (CP-533,536), an EP2 receptor-selective prostaglandin E2 agonist: characterization of metabolites by high-resolution liquid chromatography-tandem mass spectrometry and liquid chromatography/mass spectrometry-nuclear magnetic resonance.

    PubMed

    Prakash, Chandra; Wang, Weiwei; O'Connell, Thomas; Johnson, Kim A

    2008-10-01

    CP-533,536, (3-{[(4-tert-butyl-benzyl)-(pyridine-3-sulfonyl)-amino]-methyl}-phenoxy)-acetic acid (1), an EP2 receptor-selective prostaglandin E2 agonist, is being developed to aid in the healing of bone fractures. To support the development of this program, in vitro metabolism of 1 was investigated in human liver microsomes and major recombinant human cytochrome P450 (P450) isoforms. 1 was metabolized in vitro by at least three recombinant human P450s: CYP3A4, CYP3A5, and CYP2C8. The turnover of 1 was NADPH-dependent and was completely inhibited by ketoconazole and quercetin in the CYP3A4/5 and CYP2C8 incubations, respectively. The major metabolic pathways were caused by oxidation of the tert-butyl moiety to form the omega-hydroxy metabolite (M4), oxidation of the pyridine moiety, and/or N-dealkylation of the methylphenoxy acetic acid moiety. The alcohol metabolite M4 was further oxidized to the corresponding carboxylic acid M3. In addition to these pathways, three unusual metabolites (M22, M23, and M26) resulting from C-demethylation of the tert-butyl group were identified using high-resolution liquid chromatography/tandem mass spectrometry and liquid chromatography/mass spectrometry/NMR. The C-demethylated metabolites were not detected on incubation of carboxylic acid metabolite M3 with either human liver microsomes or CYP3A/2C8 isoforms, suggesting that these metabolites were not derived from decarboxylation of M3. A possible mechanism for C-demethylation may involve the oxidation of M4 to form an aldehyde metabolite (M24), followed by P450-mediated deformylation, to give an unstable carbon-centered radical and formic acid. The carbon-centered radical intermediate then undergoes either oxygen rebound to form an alcohol metabolite M23 or hydrogen abstraction leading to an olefin metabolite M26. PMID:18653741

  7. C-H activation versus yttrium-methyl cation formation from [Y(AlMe4)3] induced by cyclic polynitrogen bases: solvent and substituent-size effects.

    PubMed

    Bojer, Daniel; Venugopal, Ajay; Mix, Andreas; Neumann, Beate; Stammler, Hans-Georg; Mitzel, Norbert W

    2011-05-23

    The reaction of 1,3,5-triisopropyl-1,3,5-triazacyclohexane (TiPTAC) with [Y(AlMe(4))(3)] resulted in the formation of [(TiPTAC)Y(Me(3)AlCH(2)AlMe(3))(μ-MeAlMe(3))] by C-H activation and methane extrusion. In contrast, the presence of bulkier cyclohexyl groups on the nitrogen atoms in 1,3,5-tricyclohexyl-1,3,5-triazacyclohexane (TCyTAC) led to the formation of the cationic dimethyl complex [(TCyTAC)(2)YMe(2)][AlMe(4)]. The investigations reveal a dependency of the reaction mechanism on the steric bulk of the N-alkyl entity and the solvent employed. In toluene C-H activation was observed in reactions of [Y(AlMe(4))(3)] with 1,3,5-trimethyl-1,3,5-triazacyclohexane (TMTAC) and TiPTAC. In THF molecular dimethyl cations, such as [(TCyTAC)(2)YMe(2)][AlMe(4)], [(TMTAC)(2)YMe(2)][AlMe(4)] and [(TiPTAC)(2)YMe(2)][AlMe(4)], could be synthesised by addition of the triazacyclohexane at a later stage. The THF-solvated complex [YMe(2)(thf)(5)][AlMe(4)] could be isolated and represents an intermediate in these reactions. It shows that cationic methyl complexes of the rare-earth metals can be formed by donor-induced cleavage of the rare-earth-metal tetramethylaluminates. The compounds were characterised by single-crystal X-ray diffraction or multinuclear and variable-temperature NMR spectroscopy, as well as elemental analyses. Variable-temperature NMR spectroscopy illustrates the methyl group exchange processes between the cations and anions in solution. PMID:21503986

  8. Metabolic activation of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine and DNA adduct formation depends on p53: Studies in Trp53(+/+),Trp53(+/-) and Trp53(-/-) mice.

    PubMed

    Krais, Annette M; Speksnijder, Ewoud N; Melis, Joost P M; Singh, Rajinder; Caldwell, Anna; Gamboa da Costa, Gonçalo; Luijten, Mirjam; Phillips, David H; Arlt, Volker M

    2016-02-15

    The expression of the tumor suppressor p53 can influence the bioactivation of, and DNA damage induced by, the environmental carcinogen benzo[a]pyrene, indicating a role for p53 in its cytochrome P450 (CYP)-mediated biotransformation. The carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), which is formed during the cooking of food, is also metabolically activated by CYP enzymes, particularly CYP1A2. We investigated the potential role of p53 in PhIP metabolism in vivo by treating Trp53(+/+), Trp53(+/-) and Trp53(-/-) mice with a single oral dose of 50 mg/kg body weight PhIP. N-(Deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP-C8-dG) levels in DNA, measured by liquid chromatography-tandem mass spectrometry, were significantly lower in liver, colon, forestomach and glandular stomach of Trp53(-/-) mice compared to Trp53(+/+) mice. Lower PhIP-DNA adduct levels in the livers of Trp53(-/-) mice correlated with lower Cyp1a2 enzyme activity (measured by methoxyresorufin-O-demethylase activity) in these animals. Interestingly, PhIP-DNA adduct levels were significantly higher in kidney and bladder of Trp53(-/-) mice compared to Trp53(+/+) mice, which was accompanied by higher sulfotransferase (Sult) 1a1 protein levels and increased Sult1a1 enzyme activity (measured by 2-naphthylsulfate formation from 2-naphthol) in kidneys of these animals. Our study demonstrates a role for p53 in the metabolism of PhIP in vivo, extending previous results on a novel role for p53 in xenobiotic metabolism. Our results also indicate that the impact of p53 on PhIP biotransformation is tissue-dependent and that in addition to Cyp1a enzymes, Sult1a1 can contribute to PhIP-DNA adduct formation. PMID:26335255

  9. Lipid droplets formation in human endothelial cells in response to polyunsaturated fatty acids and 1-methyl-nicotinamide (MNA); confocal Raman imaging and fluorescence microscopy studies.

    PubMed

    Majzner, Katarzyna; Chlopicki, Stefan; Baranska, Malgorzata

    2016-04-01

    In this work the formation of lipid droplets (LDs) in human endothelial cells culture in response to the uptake of polyunsaturated fatty acids (PUFAs) was studied. Additionally, an effect of 1-methylnicotinamide (MNA) on the process of LDs formation was investigated. LDs have been previously described structurally and to some degree biochemically, however neither the precise function of LDs nor the factors responsible for LD induction have been clarified. Lipid droplets, sometimes referred in the literature as lipid bodies are organelles known to regulate neutrophil, eosinophil, or tumor cell functions but their presence and function in the endothelium is largely unexplored. 3D linear Raman spectroscopy was used to study LDs formation in vitro in a single endothelial cell. The method provides information about distribution and size of LDs as well as their composition. The incubation of endothelial cells with various PUFAs resulted in formation of LDs. As a complementary method for LDs identification a fluorescence microscopy was applied. Fluorescence measurements confirmed the Raman results suggesting endothelial cells uptake of PUFAs and subsequent LDs formation in the cytoplasm of the endothelium. Furthermore, MNA seem to potentiate intracellular uptake of PUFAs to the endothelium that may bear physiological and pharmacological significance. Confocal Raman imaging of HAoEC cell with LDs. PMID:25966299

  10. Online Measurement of the Intramolecular Isotopic Composition of Acetate in Natural Porewater Samples

    NASA Astrophysics Data System (ADS)

    Thomas, R. B.; Arthur, M. A.; Freeman, K. H.

    2006-12-01

    Carbon dioxide and methane are traditionally considered to be the dominant end products of anaerobic metabolism while acetate is thought to be a rapidly consumed intermediate. However, in some settings, recent evidence has grown to suggest that, at least transiently, acetate can be a major metabolic end product. In natural systems, isotopic mass balances can be used to partition the flow of carbon to methane, CO2, and acetate. However, these isotopic estimates require intramolecular measurements of acetate in addition to isotopic measurements of the gaseous species, CO2 and CH4. In practice, the intramolecular isotopic composition of acetate is rarely measured because the analysis is technically challenging and traditionally requires prior separation and offline pyrolysis of purified acetate. As a result of these technical challenges, acetate methyl carbon is usually assumed to be a few permil depleted relative to the carbon isotopic composition of bulk organic matter. In environments where acetate may be produced by autotrophic acetogens this assumption can be devastatingly false. This work describes the use of an online method for the analysis of the intramolecular carbon isotopic composition of dissolved acetate from dilute surface water samples with a detection limit of injected sample down to 500uM. Preconcentration of samples via lyophilization has resulted in detection limits as low as 30uM. In 2002, at Penn State, Dias et al. (Organic Geochemistry Vol. 33, p161-168) reported a technique to examine the intramolecular isotopic composition of acetate from oil-prone source rocks using SPME extraction with an online GC-pyrolysis-IRMS. We have adapted the Dias method to be used with direct injection of dilute natural water samples. Briefly, this procedure protonates acetate with a .1M addition of oxalic acid and vaporizes the sample in the GC inlet at low temperatures. This prevents oxalic acid decomposition and provides sufficient separation of acetate from

  11. Specificity of sites within eight-membered ring zeolite channels for carbonylation of methyls to acetyls.

    PubMed

    Bhan, Aditya; Allian, Ayman D; Sunley, Glenn J; Law, David J; Iglesia, Enrique

    2007-04-25

    The acid-catalyzed formation of carbon-carbon bonds from C1 precursors via CO insertion into chemisorbed methyl groups occurs selectively within eight-membered ring (8-MR) zeolite channels. This elementary step controls catalytic carbonylation rates of dimethyl ether (DME) to methyl acetate. The number of O-H groups within 8-MR channels was measured by rigorous deconvolution of the infrared bands for O-H groups in cation-exchanged and acid forms of mordenite (M,H-MOR) and ferrierite (H-FER) after adsorption of basic probe molecules of varying size. DME carbonylation rates are proportional to the number of O-H groups within 8-MR channels. Na+ cations selectively replaced protons within 8-MR channels and led to a disproportionate decrease in carbonylation turnover rates (per total H+). These conclusions are consistent with the low or undetectable rates of carbonylation on zeolites without 8-MR channels (H-BEA, H-FAU, H-MFI). Such specificity of methyl reactivity upon confinement within small channels appears to be unprecedented in catalysis by microporous solids, which typically select reactions by size exclusion of bulkier transition states. PMID:17397162

  12. Experimental study of the hydrothermal reactivity of organic acids and acid anions: II. Acetic acid, acetate, and valeric acid

    NASA Astrophysics Data System (ADS)

    McCollom, Thomas M.; Seewald, Jeffrey S.

    2003-10-01

    Organic acids and acid anions occur in substantial concentrations in many aqueous geologic fluids and are thought to take part in a variety of geochemical processes ranging from the transport of metals in ore-forming fluids to the formation of natural gas to serving as a metabolic energy source for microbes in subsurface habitats. The widespread occurrence of organic acids and their potential role in diverse geologic processes has led to numerous experimental studies of their thermal stability, yet there remain substantial gaps in our knowledge of the factors that control the rates and reaction pathways for the decomposition of these compounds under geologic conditions. In order to address some of these uncertainties, a series of laboratory experiments were conducted to examine the behavior of organic acids and acid anions under hydrothermal conditions in the presence of minerals. Reported here are results of experiments where aqueous solutions of acetic acid, sodium acetate, or valeric acid ( n-pentanoic acid) were heated at 325°C, 350 bars in the presence of the mineral assemblages hematite + magnetite + pyrite, pyrite + pyrrhotite + magnetite, and hematite + magnetite. The results indicate that aqueous acetic acid and acetate decompose by a combination of two reaction pathways: decarboxylation and oxidation. Both reactions are promoted by minerals, with hematite catalyzing the oxidation reaction while magnetite catalyzes decarboxylation. The oxidation reaction is much faster, so that oxidation dominates the decomposition of acetic acid and acetate when hematite is present. In contrast to previous reports that acetate decomposed more slowly than acetic acid, we found that acetate decomposed at slightly faster rates than the acid in the presence of minerals. Although longer-chain monocarboxylic acids are generally thought to decompose by decarboxylation, valeric acid appeared to decompose primarily by "deformylation" to 1-butene plus formic acid. Subsequent

  13. 21 CFR 522.533 - Deslorelin acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Deslorelin acetate. (a) Specifications. Each implant contains 2.1 milligrams deslorelin acetate. (b) Sponsor.... One implant per mare. (ii) Indications for use. For inducing ovulation within 48 hours in...

  14. Ozone decomposition in aqueous acetate solutions

    SciTech Connect

    Sehested, K.; Holcman, J.; Bjergbakke, E.; Hart, E.J.

    1987-01-01

    The acetate radical ion reacts with ozone with a rate constant of k = (1.5 +/- 0.5) x 10Z dmT mol s . The products from this reaction are CO2, HCHO, and O2 . By subsequent reaction of the peroxy radical with ozone the acetate radical ion is regenerated through the OH radical. A chain decomposition of ozone takes place. It terminates when the acetate radical ion reacts with oxygen forming the unreactive peroxy acetate radical. The chain is rather short as oxygen is developed, as a result of the ozone consumption. The inhibiting effect of acetate on the ozone decay is rationalized by OH scavenging by acetate and successive reaction of the acetate radical ion with oxygen. Some products from the bimolecular disappearance of the peroxy acetate radicals, however, react further with ozone, reducing the effectiveness of the stabilization.

  15. Mesoscale simulation of the formation and dynamics of lipid-structured poly(ethylene oxide)-block-poly(methyl methacrylate) diblock copolymers.

    PubMed

    Mu, Dan; Li, Jian-Quan; Feng, Sheng-Yu

    2015-05-21

    Twelve poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA) copolymers with lipid-like structures were designed and investigated by MesoDyn simulation. Spherical and worm-like micelles as well as bicontinuous, lamellar and defected lamellar phases were obtained. A special structure, designated B2412, with two lipid structures connected by their heads, was found to undergo four stages prior to forming a spherical micelle phase. Two possible assembly mechanisms were found via thermodynamic and dynamic process analyses; namely, the fusion and fission of micelles in dynamic equilibrium during the adjustment stage. Water can be encapsulated into these micelles, which can affect their size, particularly in low concentration aqueous solutions. The assignment of weak negative charges to the hydrophilic EO blocks resulted in a clear effect on micelle size. Surprisingly, the largest effect was observed with EO blocks with -0.5 e, wherein an ordered perfect hexagonal phase was formed. The obtained results can be applied in numerous fields of study, including adsorption, catalysis, controlled release and drug delivery. PMID:25898853

  16. Analysis of a pyruvic acid acetal-containing polysaccharide by the reductive-cleavage method.

    PubMed

    Zeller, S G; Gray, G R

    1991-04-24

    The applicability of the reductive-cleavage method to the analysis of polysaccharides bearing pyruvic acid acetals has been demonstrated. Direct reductive cleavage of fully methylated gum xanthan yielded the expected products, including 1,5-anhydro-4,6-O-[(S)-1-methoxycarbonylethylidene]-2,3-di-O-methy l-D- mannitol. The latter product was not observed when reductive cleavage was performed subsequent to reduction of ester groups in the fully methylated polysaccharide and mild hydrolysis to remove pyruvic acid acetal substituents. Instead, the latter experiment yielded 1,5-anhydro-2,3-di-O-methyl-D-mannitol, establishing the presence in the polysaccharide of terminal (nonreducing) D-mannopyranosyl groups bearing 4,6-O-(1-carboxyethylidene) substituents. The products of reductive cleavage were characterized, where appropriate, by comparison of the gas chromatographic retention times and chemical ionization- and electron ionization-mass spectra of their acetates to those of authentic standards. Alternatively, the products of reductive cleavage could be characterized without resort to comparison with authentic standards by analysis of the 1H-n.m.r. spectra of their benzoates, which were obtained in pure form by high-performance liquid chromatography. By either method of product characterization, this two-step procedure of analysis reveals the presence of pyruvic-acetal residues in polysaccharides and establishes both the identity of the sugar residue to which they are attached and their positions of attachment. PMID:1769016

  17. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and....1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant and animal tissues....

  18. Factors affecting the selectivity of the oxidation of methyl p-toluate by cobalt(III).

    PubMed

    Sumner, Charles E; Morrill, Kent A; Howell, Jeff S; Little, James

    2008-03-17

    The anaerobic oxidation of methyl p-toluate by cobalt(III) in acetic acid was investigated. Observed products were 4-carbomethoxybenzaldehyde (2), 4-carbomethoxybenzoic acid (3), 4-carbomethoxybenzyl acetate (1), 4,4'-dicarbomethoxybibenzyl (6), methyl 2,4-dimethylbenzoate (8), and methyl 3,4-dimethylbenzoate (9). Deuterium isotope labeling showed that 2 was not formed from 1, but appeared to be formed directly from methyl p-toluate via 4-carbomethoxybenzyl alcohol (5). The ratio of (2 + 3) to 1 was 0.5 with [py3Co3O(OAc)5OH[PF6] and 1.0 with cobaltic acetate. Cobaltic acetate was generated in situ by the reaction of cobaltous acetate and peracetic acid. When the oxidation was carried out in the presence of chromium (0.05 equiv based on cobalt), the ratio increased dramatically and no 6 was observed. Other transition metals such as vanadium, molybdenum, and manganese had a similar effect, but were not as effective as chromium. Chromium was observed to form a mixed-metal cluster complex with cobalt. Treatment of an acetic acid solution of cobaltous acetate and methyl isonicotinate with K2CrO4 produced a solid tentatively identified as [(MIN)3Co2CrO(OAc)6][CrO4H] (MIN = methyl isonicotinate). The selectivity for the oxidation of methyl p-toluate exhibited by the mixed-metal cluster complex was similar to that observed by the addition of chromium to oxidations using [py3Co3O(OAc)5OH[PF6]. PMID:18225893

  19. Kinetics of the Methanogenic Fermentation of Acetate

    PubMed Central

    Fukuzaki, Satoshi; Nishio, Naomichi; Nagai, Shiro

    1990-01-01

    Inhibition of the fermentation of acetate to methane and carbon dioxide by acetate was analyzed with an acetate-acclimatized sludge and with Methanosarcina barkeri Fusaro under mesophilic conditions. A second-order substrate inhibition model, qch4 = qmS/[Ks + S + (S2/Ki)], where S was the concentration of undissociated acetic acid, not ionized acetic acid, could be applicable in both cases. The analysis resulted in substrate saturation constants, Ks, of 4.0 μM for the acclimatized sludge and 104 μM for M. barkeri. The threshold concentrations of undissociated acetic acid when no further acetate utilization was observed were 0.078 μM (pH 7.50) for the acclimatized sludge and 4.43 μM (pH 7.45) for M. barkeri. These kinetic results suggested that the concentration of undissociated acetic acid became a key factor governing the actual threshold acetate concentration for acetate utilization and that the acclimatized sludge in which Methanothrix spp. appeared dominant could utilize acetate better and survive at a lower concentration of undissociated acetic acid than could M. barkeri. Images PMID:16348323

  20. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... days. (A) 140 milligrams (mg) trenbolone acetate (one implant consisting of 7 pellets, each pellet containing 20 mg trenbolone acetate) per implant dose. (B) 140 mg trenbolone acetate (one implant consisting... 29 mg tylosin tartrate) per implant dose. (ii) Indications for use. For improved feed...

  1. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... days. (A) 140 milligrams (mg) trenbolone acetate (one implant consisting of 7 pellets, each pellet containing 20 mg trenbolone acetate) per implant dose. (B) 140 mg trenbolone acetate (one implant consisting... 29 mg tylosin tartrate) per implant dose. (ii) Indications for use. For improved feed...

  2. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... days. (A) 140 milligrams (mg) trenbolone acetate (one implant consisting of 7 pellets, each pellet containing 20 mg trenbolone acetate) per implant dose. (B) 140 mg trenbolone acetate (one implant consisting... 29 mg tylosin tartrate) per implant dose. (ii) Indications for use. For improved feed...

  3. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... days. (A) 140 milligrams (mg) trenbolone acetate (one implant consisting of 7 pellets, each pellet containing 20 mg trenbolone acetate) per implant dose. (B) 140 mg trenbolone acetate (one implant consisting... 29 mg tylosin tartrate) per implant dose. (ii) Indications for use. For improved feed...

  4. 21 CFR 582.6185 - Calcium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium acetate. 582.6185 Section 582.6185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium acetate. (a) Product. Calcium acetate. (b) Conditions of use. This substance is...

  5. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  6. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It...

  7. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  8. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  9. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  10. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  11. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  12. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  13. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  14. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  15. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  16. Crystal structure of febuxostat-acetic acid (1/1).

    PubMed

    Wu, Min; Hu, Xiu-Rong; Gu, Jian-Ming; Tang, Gu-Ping

    2015-05-01

    The asymmetric unit of the title compound [systematic name: 2-(3-cyano-4-iso-butyl-oxyphen-yl)-4-methyl-thia-zole-5-carb-oxy-lic acid-acetic acid (1/1)], C16H16N2O3S·CH3COOH, contains a febuxostat mol-ecule and an acetic acid mol-ecule. In the febuxostat mol-ecule, the thia-zole ring is nearly coplanar with the benzene ring [dihedral angle = 3.24 (2)°]. In the crystal, the febuxostat and acetic acid mol-ecules are linked by O-H⋯O, O-H⋯N hydrogen bonds and weak C-H⋯O hydrogen bonds, forming supra-molecular chains propagating along the b-axis direction. π-π stacking is observed between nearly parallel thia-zole and benzene rings of adjacent mol-ecules; the centroid-to-centroid distances are 3.8064 (17) and 3.9296 (17) Å. PMID:25995912

  17. Acetate and CO2 assimilation by Methanothrix concilii.

    PubMed

    Ekiel, I; Sprott, G D; Patel, G B

    1985-06-01

    Biosynthetic pathways in Methanothrix concilii, a recently isolated aceticlastic methanogen, were studied by 13C-nuclear magnetic resonance spectroscopy. Labeling patterns of amino acids, lipids, and carbohydrates were determined. Similar to other methanogens, acetate was carboxylated to pyruvate, which was further converted to amino acids by various biosynthetic pathways. The origin of carbon atoms in glutamate, proline, and arginine clearly showed that an incomplete tricarboxylic acid cycle operating in the oxidative direction was used for their biosynthesis. Isoleucine was synthesized via citramalate, which is a typical route for methanogens. As with Methanosarcina barkeri, an extensive exchange of the label between the carboxyl group of acetate and CO2 was observed. Lipids predominantly contained diphytanyl chains, the labeling of which indicated that biosynthesis proceeded through mevalonic acid. Labeling of the C-1,6 of glucose from [2-13C]acetate is consistent with a glucogenic route for carbohydrate biosynthesis. Except for the different origins of the methyl group of methionine, the metabolic properties of Methanothrix concilii are closely related to those of Methanosarcina barkeri. PMID:3922956

  18. Formation of NR1/NR2 and NR1/NR3 heterodimers constitutes the initial step in N-methyl-D-aspartate receptor assembly.

    PubMed

    Schüler, Thomas; Mesic, Ivana; Madry, Christian; Bartholomäus, Ingo; Laube, Bodo

    2008-01-01

    N-Methyl-D-aspartate (NMDA) receptors are tetrameric protein complexes composed of the glycine-binding NR1 subunit with a glutamate-binding NR2 and/or glycine-binding NR3 subunit. Tri-heteromeric receptors containing NR1, NR2, and NR3 subunits reconstitute channels, which differ strikingly in many properties from the respective glycine- and glutamate-gated NR1/NR2 complexes and the NR1/NR3 receptors gated by glycine alone. Therefore, an accurate oligomerization process of the different subunits has to assure proper NMDA receptor assembly, which has been assumed to occur via the oligomerization of homodimers. Indeed, using fluorescence resonance energy transfer analysis of differentially fluorescence-tagged subunits and blue native polyacrylamide gel electrophoresis after metabolic labeling and affinity purification revealed that the NR1 subunit is capable of forming homo-oligomeric aggregates. In contrast, both the NR2 and the NR3 subunits formed homo- and hetero-oligomers only in the presence of the NR1 subunit indicating differential roles of the subunits in NMDA receptor assembly. However, co-expression of the NR3A subunit with an N-terminal domain-deleted NR1 subunit (NR1(DeltaNTD)) abrogating NR1 homo-oligomerization did not affect NR1/NR3A receptor stoichiometry or function. Hence, homo-oligomerization of the NR1 subunit is not essential for proper NR1/NR3 receptor assembly. Because identical results were obtained for NR1(DeltaNTD)/NR2 NMDA receptors (Madry, C., Mesic, I., Betz, H., and Laube, B. (2007) Mol. Pharmacol., 72, 1535-1544) and NR1-containing hetero-oligomers are readily formed, we assume that heterodimerization of the NR1 with an NR3 or NR2 subunit, which is followed by the subsequent association of two heterodimers, is the key step in determining proper NMDA receptor subunit assembly and stoichiometry. PMID:17959602

  19. Pharmacokinetics of depot medroxyprogesterone acetate contraception.

    PubMed

    Mishell, D R

    1996-05-01

    Depot medroxyprogesterone acetate (DMPA) is an aqueous suspension of 17-acetoxy 6-methyl progestin administered by intramuscular injection for long-term contraception. This highly effective injectable formulation of medroxyprogesterone acetate (MPA) has a prolonged duration of action since the progestin is released slowly from the muscle. MPA is detected in the serum within 30 minutes after an injection of 150 mg. Serum concentrations vary between individual women but generally plateau at about 1.0 ng/mL for about three months, after which there is a gradual decline. In some women, MPA can be detected in the serum for as long as nine months after a single injection of 150 mg. The circulating MPA initially inhibits the midcycle leutinizing hormone (LH) peak, but LH and follicle stimulating hormone (FSH) levels remain in the range of those for the luteal phase of a pretreatment control cycle. Since ovulation is inhibited, serum progesterone levels remain low (< 0.4 ng/mL) for several months following an injection of DMPA. When MPA levels fall below 0.1 ng/mL, ovulation resumes. Thus, return to fertility is delayed for several months if a woman wishes to conceive after receiving one or more injections of DMPA. Following an injection of DMPA, serum estradiol levels initially are in the early to midfollicular phase range (mean approximately 50 pg/nL). Serum estradiol levels begin to rise about four months after a single injection when MPA levels fall below 0.5 ng/mL. For women who have used DMPA for several years, serum estradiol levels range between 10 and 92 pg/mL, with mean levels of about 40 pg/mL. Despite these low levels of estradiol, hot flushes are a rare event, and the vaginal epithelium remains moist and well rugated. Women using DMPA for several years do not observe a change in breast size. DMPA causes the endometrium to become atrophic, with small, straight endometrial glands and decidualized stroma. The cervical mucus remains thick and viscid. DMPA is a

  20. Microbiosensor for the detection of acetate in electrode-respiring biofilms.

    PubMed

    Atci, Erhan; Babauta, Jerome T; Sultana, Sujala T; Beyenal, Haluk

    2016-07-15

    The goal of this work was to develop a microbiosensor to measure acetate concentration profiles inside biofilms in situ. The working principle of the microbiosensor was based on the correlation between the acetate concentration and the current generated during acetate oxidation by Geobacter sulfurreducens. The microbiosensor consisted of a 30-µm carbon microelectrode with an open tip as a working electrode, with G. sulfurreducens biofilm on the tip and a pseudo Ag/AgCl reference electrode, all enclosed in a glass outer case with a 30-µm tip diameter. The microbiosensor showed a linear response in the 0-1.6mM acetate concentration range with a 79±8µM limit of detection (S/N=2). We quantified the stirring effect and found it negligible. However, the interfering effect of alternative electron donors (lactate, formate, pyruvate, or hydrogen) was found to be significant. The usefulness of the acetate microbiosensor was demonstrated by measuring acetate concentration depth profiles within a G. sulfurreducens biofilm. The acetate concentration remained at bulk values throughout the biofilm when no current was passed, but it decreased from the bulk values to below the detection limit within 200µm when current was allowed to pass. The zero acetate concentration at the bottom of the biofilm showed that the biofilm was acetate-limited. PMID:27016913

  1. Bacterial response to acetate challenge: a comparison of tolerance among species.

    PubMed

    Lasko, D R; Zamboni, N; Sauer, U

    2000-08-01

    Although acetate formation and tolerance are important criteria for various aspects of biotechnological process development, available studies on acetate tolerance in different species are disparate. We evaluate the response of eight bacterial strains, including two variants of Escherichia coli, two variants of Staphylococcus capitis, and one each of Acetobacter aceti, Gluconobacter suboxydans, Lactobacillus acetotolerans, and L. bulgaricus, to acetate challenges under identical conditions. Our findings were: (1) wild-type organisms of species that are considered tolerant of acetate perform only slightly better than E. coli in unadapted shaker cultures; (2) the ability to tolerate acetate is strongly dependent on the carbon source, and is, especially for E. coli, much greater on glycerol than on glucose; (3) respiration is not as important to acetate tolerance in E. coli and S. capitis as has been reported for the acetic acid bacteria; (4) S. capitis was the least affected by acetate under all conditions and grew at up to 44 g/l acetate without any preconditioning; and (5) qualitative high-throughput screening of growth characteristics can be achieved with relatively inexpensive multiwell plate readers. PMID:10968640

  2. The potentiometric determination of stability constants for zinc acetate complexes in aqueous solutions to 295C

    SciTech Connect

    Giordano, T.H. ); Drummond, S.E. )

    1991-09-01

    A potentiometric method was used to determine the formation quotients of zinc acetate complexes in aqueous solutions from 50 to 295C at ionic strengths of 0.03, 0.3, and 1.0 m. The potentiometric titrations were carried out in an externally heated, Teflon-lined concentration cell fitted with hydrogen electrodes. Formal sodium acetate concentrations of the experimental solutions ranged from 0.001 to 0.1 m with acetic acid to sodium acetate ratios ranging from 30 to 300. Sodium trifluoromethanesulfonate (F{sub 3}CSO{sub 3}Na) was used as a supporting electrolyte. Stoichiometries and formation quotients for the complexes ZnCH{sub 3}COO{sup +}, Zn(CH{sub 3}COO){sub 2}, and Zn(CH{sub 3}COO){sub 3}{sup {minus}} were derived from the titration data by regression analysis. Stability constants at infinite dilution (K{sub n}) and other relevant thermodynamic quantities were calculated for these three complexes. Calculations of zinc speciation in acetate-chloride solutions show that zinc acetate complexes should have an importance similar to zinc chloride complexes in high acetate waters where chloride to acetate molal ratios are less than about 10.

  3. Formation Mechanism of the First Carbon-Carbon Bond and the First Olefin in the Methanol Conversion into Hydrocarbons.

    PubMed

    Liu, Yue; Müller, Sebastian; Berger, Daniel; Jelic, Jelena; Reuter, Karsten; Tonigold, Markus; Sanchez-Sanchez, Maricruz; Lercher, Johannes A

    2016-05-01

    The elementary reactions leading to the formation of the first carbon-carbon bond during early stages of the zeolite-catalyzed methanol conversion into hydrocarbons were identified by combining kinetics, spectroscopy, and DFT calculations. The first intermediates containing a C-C bond are acetic acid and methyl acetate, which are formed through carbonylation of methanol or dimethyl ether even in presence of water. A series of acid-catalyzed reactions including acetylation, decarboxylation, aldol condensation, and cracking convert those intermediates into a mixture of surface bounded hydrocarbons, the hydrocarbon pool, as well as into the first olefin leaving the catalyst. This carbonylation based mechanism has an energy barrier of 80 kJ mol(-1) for the formation of the first C-C bond, in line with a broad range of experiments, and significantly lower than the barriers associated with earlier proposed mechanisms. PMID:27037603

  4. Effect of amino acids on the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in creatinine/phenylalanine and creatinine/phenylalanine/4-oxo-2-nonenal reaction mixtures.

    PubMed

    Zamora, Rosario; Alcón, Esmeralda; Hidalgo, Francisco J

    2013-12-15

    2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation in mixtures of creatinine, phenylalanine, amino acids and 4-oxo-2-nonenal was studied, to analyse the role of amino acids on the generation of this heterocyclic aromatic amine. When oxidised lipid was absent, cysteine, serine, aspartic acid, threonine, asparagine, tryptophan, tyrosine, proline, and methionine increased significantly (p < 0.05) the amount of PhIP formed in comparison to the control. When lipid was present, only the addition of methionine, glycine, and serine increased significantly (p < 0.05) the amount of PhIP produced, while histidine, cysteine, lysine, tryptophan, tyrosine, and alanine reduced significantly (p < 0.05) PhIP. These results may be a consequence of the different competitive reactions that occur. Thus, in the absence of lipids, thermal decomposition of the amino acids produced reactive carbonyls that converted phenylalanine into phenylacetaldehyde as a key step in the formation of PhIP. When oxidised lipid was present, amino acids competed with phenylalanine for the lipid, and amino acid degradation products were formed, among which alpha-keto acids seemed to play a role in these reactions. These results suggest that PhIP can be produced by several alternative reaction pathways from all major food components, including amino acids and lipids, in addition to carbohydrates. PMID:23993611

  5. Effects of the amino-carbonyl reaction of ribose and glycine on the formation of the 2(or 5)-ethyl-5(or 2)-methyl-4-hydroxy-3(2H)-furanone aroma component specific to miso by halo-tolerant yeast.

    PubMed

    Sugawara, Etsuko; Ohata, Motoko; Kanazawa, Toshinari; Kubota, Kikue; Sakurai, Yonekichi

    2007-07-01

    The formation of HEMF[2(or 5)-ethyl-5(or 2)-methyl-4-hydroxy-3(2H)-furanone], the aroma component specific to miso and soy sauce, was promoted by cultivating the halo-tolerant yeast, Zygosaccharomyces rouxii, in a medium including the amino-carbonyl reaction products based on ribose and glycine. The glucose concentration in the medium influenced the HEMF formation by Z. rouxii. PMID:17617718

  6. Effect of evaporation time on cellulose acetate membrane for gas separation

    NASA Astrophysics Data System (ADS)

    Jami'an, W. N. R.; Hasbullah, H.; Mohamed, F.; Yusof, N.; Ibrahim, N.; Ali, R. R.

    2016-06-01

    Throughout this decades, membrane technology has been the desirable option among the others gas separation technologies. However, few issues have been raised regarding the membrane gas separation application including the trade-off between its permeability and selectivity and also its effects towards environment. Therefore, for this research, a biopolymer membrane for gas separation application will be developed with reasonably high on both permeability and selectivity. The main objective of this research is to study the effect of solvent evaporation time on the flat sheet asymmetric membrane morphology and gas separation performance. The membranes were produced by a simple dry/wet phase inversion technique using a pneumatically controlled casting system. The dope solution for the membrane casting was prepared by dissolving the cellulose acetate (CA) polymer in N-Methyl-2-pyrrolidone (NMP) and the solvent evaporation time was varied. Permeability and selectivity of the membrane was performed by using pure gases of carbon dioxide, CO2 and methane, CH4. The increase in solvent evaporation time had improved the membrane morphologies as the porosity of the membrane surface decrease and formation of a more mature skin layer. The gas permeation tests determined that increasing in solvent evaporation time had increased the selectivity of CO2/CH4 but reduce the permeability of both gases

  7. Acetic acid suppresses the increase in disaccharidase activity that occurs during culture of caco-2 cells.

    PubMed

    Ogawa, N; Satsu, H; Watanabe, H; Fukaya, M; Tsukamoto, Y; Miyamoto, Y; Shimizu, M

    2000-03-01

    To understand how blood glucose level is lowered by oral administration of vinegar, we examined effects of acetic acid on glucose transport and disaccharidase activity in Caco-2 cells. Cells were cultured for 15 d in a medium containing 5 mmol/L of acetic acid. This chronic treatment did not affect cell growth or viability, and furthermore, apoptotic cell death was not observed. Glucose transport, evaluated with a nonmetabolizable substrate, 3-O-methyl glucose, also was not affected. However, the increase of sucrase activity observed in control cells (no acetic acid) was significantly suppressed by acetic acid (P < 0.01). Acetic acid suppressed sucrase activity in concentration- and time-dependent manners. Similar treatments (5 mmol/L and 15 d) with other organic acids such as citric, succinic, L-maric, L-lactic, L-tartaric and itaconic acids, did not suppress the increase in sucrase activity. Acetic acid treatment (5 mmol/L and 15 d) significantly decreased the activities of disaccharidases (sucrase, maltase, trehalase and lactase) and angiotensin-I-converting enzyme, whereas the activities of other hydrolases (alkaline phosphatase, aminopeptidase-N, dipeptidylpeptidase-IV and gamma-glutamyltranspeptidase) were not affected. To understand mechanisms underlying the suppression of disaccharidase activity by acetic acid, Northern and Western analyses of the sucrase-isomaltase complex were performed. Acetic acid did not affect the de novo synthesis of this complex at either the transcriptional or translational levels. The antihyperglycemic effect of acetic acid may be partially due to the suppression of disaccharidase activity. This suppression seems to occur during the post-translational processing. PMID:10702577

  8. DNA methylation in hematopoietic development and disease.

    PubMed

    Gore, Aniket V; Weinstein, Brant M

    2016-09-01

    DNA methylation is an important epigenetic modification that can have profound and widespread effects on gene expression and on cellular fate and function. Recent work has indicated that DNA methylation plays a critical role in hematopoietic development and hematopoietic disease. DNA methyltransferases and Ten-eleven translocation enzymes are required to add and remove methyl "marks" from DNA, respectively, and both sets of genes have been found necessary for proper formation and maintenance of hematopoietic stem cells and for differentiation of downstream hematopoietic lineages during development. DNA methylation and demethylation enzymes have also been implicated in hematopoietic disorders such as acute myeloid leukemia and myelodysplastic syndrome. Here, we review some of the recent literature regarding the role of DNA methylation in hematopoietic health and disease. PMID:27178734

  9. Atmospheric geochemistry of formic and acetic acids at a mid-latitude temperate site

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Beecher, K. M.; Harriss, R. C.; Cofer, R. W., III

    1988-01-01

    Tropospheric concentrations of formic and acetic acids in the gas, the aerosol, and the rainwater phases were determined in samples collected 1-2 m above ground level at an open field site in eastern Virginia. These acids were found to occur principally (98 percent or above) in the gas phase, with a marked annual seasonality, averaging 1890 ppt for formate and 1310 ppt for acetate during the growing season, as compared to 695 ppt and 700 ppt, respectively, over the nongrowing season. The data support the hypothesis that biogenic emissions from vegatation are important sources of atmospheric formic and acetic acid during the local growing season. The same time trends were observed for precipitation, although with less defined seasonality. The relative increase of the acetic acid/formic acid ratio during the nongrowing season points to the dominance of anthropogenic inputs of acetic acid from motor vehicles and biomass combustion in the wintertime.

  10. Design, Synthesis, and Antimycobacterial Activity of Novel Theophylline-7-Acetic Acid Derivatives With Amino Acid Moieties.

    PubMed

    Stavrakov, Georgi; Valcheva, Violeta; Voynikov, Yulian; Philipova, Irena; Atanasova, Mariyana; Konstantinov, Spiro; Peikov, Plamen; Doytchinova, Irini

    2016-03-01

    The theophylline-7-acetic acid (7-TAA) scaffold is a promising novel lead compound for antimycobacterial activity. Here, we derive a model for antitubercular activity prediction based on 14 7-TAA derivatives with amino acid moieties and their methyl esters. The model is applied to a combinatorial library, consisting of 40 amino acid and methyl ester derivatives of 7-TAA. The best three predicted compounds are synthesized and tested against Mycobacterium tuberculosis H37Rv. All of them are stable, non-toxic against human cells and show antimycobacterial activity in the nanomolar range being 60 times more active than ethambutol. PMID:26502828

  11. In-house development of an optimized synthetic module for routine [11C]acetate production

    PubMed Central

    Jang, Hwa Youn; Kwon, Seong Young; Pyo, Ayoung; Hur, Min Goo; Kim, Sang Wook; Park, Jeong-Hoon; Kim, Hee-Jung; Yang, Seung Dae; Lee, Sunwoo; Kim, Dong-Yeon

    2015-01-01

    [11C]Acetate, a radiotracer for PET imaging, is a promising radiopharmaceutical for overcoming the limitation of 2-deoxy-2-[18F]fluoro-d-glucose in a number of cancers. Here, the optimized automatic synthesis of [11C]acetate using an in-house-developed module under different conditions has been reported for routine production. [11C]CO2 was produced in a 16.4 MeV PETtrace cyclotron, and methyl magnesium chloride was used for synthesis. For product purification, ion-exchange solid-phase extraction cartridges were used, connected in series. High-performance liquid chromatography and gas chromatography were used to measure radiochemical and chemical purity. The Limulus amebocyte lysate test and the fluid thioglycollate medium test were performed for quality control of [11C]acetate. The total reaction time of [11C]acetate was within 15 min, and the overall decay-corrected radiochemical yield was 84.33±8.85%. Radiochemical purity was greater than 98% when evaluated on an analytical high-performance liquid chromatography system. No endotoxins or anaerobic bacteria were seen on quality control checks. Optimized production of [11C]acetate was achieved by the in-house module. Radiochemical and biological properties of the [11C]acetate produced were appropriate for clinical PET study. PMID:25244351

  12. Sunflower oil methyl ester as diesel fuel

    SciTech Connect

    Hassett, D.J.; Hasan, R.A.

    1982-01-01

    Methyl ester formation represents one approach to overcome the problems associated with the relatively high viscosity of sunflower oil when used as a diesel fuel replacement. Sunflower oil methyl ester is being prepared at the University of North Dakota Engieering Experiment Station. Physical and chemical properties of this material at varying levels of refinement and purity will be used to define fuel properties. Engine testing is being carried out to determine if the fouling characteristics of methyl ester are significantly less than those of sunflower oil. 1 figure, 1 table.

  13. An alternative mechanism for guanidinoacetic acid to affect methylation cycle.

    PubMed

    Ostojic, Sergej M

    2014-12-01

    Guanidinoacetic acid (also known as glycocyamine; GAA) is an endogenous substance which occurs in humans and plays a central role in the biosynthesis of creatine. The formation of creatine from GAA consumes methyl groups, and increases production of homocysteine. GAA may have the potential to stimulate insulin secretion. Insulin reduces plasma homocysteine and raises methyl group supply. It is possible that the ability of GAA to trigger the insulin secretion modulates methyl group metabolism, and comparatively counterbalance for the direct effect of GAA on increased methylation demand. Possible insulinotropic effect of GAA may contribute to total in vivo methylation demand during biotransformation. PMID:25468046

  14. An Experimental and Kinetic Modeling Study of Methyl Decanoate Combustion

    SciTech Connect

    Sarathy, S M; Thomson, M J; Pitz, W J; Lu, T

    2009-12-04

    Biodiesel is a mixture of long chain fatty acid methyl esters derived from fats and oils. This research study presents opposed-flow diffusion flame data for one large fatty acid methyl ester, methyl decanoate, and uses the experiments to validate an improved skeletal mechanism consisting of 648 species and 2998 reactions. The results indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene.

  15. Methyl salicylate overdose

    MedlinePlus

    Methyl salicylate (oil of wintergreen) is a chemical that smells like wintergreen. It is used in many over- ... muscle ache creams. It is related to aspirin. Methyl salicylate overdose occurs when someone swallows a dangerous amount ...

  16. Fragrance material review on p-anisyl acetate.

    PubMed

    McGinty, D; Letizia, C S; Api, A M

    2012-09-01

    A toxicologic and dermatologic review of p-anisyl acetate when used as a fragrance ingredient is presented. p-Anisyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for p-anisyl acetate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, and genotoxicity data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22417777

  17. Fragrance material review on ethyl phenyl carbinyl acetate.

    PubMed

    McGinty, D; Letizia, C S; Api, A M

    2012-09-01

    A toxicologic and dermatologic review of ethyl phenyl carbinyl acetate when used as a fragrance ingredient is presented. Ethyl phenyl carbinyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for ethyl phenyl carbinyl acetate were evaluated, then summarized, and includes: physical properties; acute toxicity; skin irritation; and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22433983

  18. Determination of Endogenous Indole-3-Acetic Acid in Plagiochila arctica (Hepaticae) 1

    PubMed Central

    Law, David M.; Basile, Dominick V.; Basile, Margaret R.

    1985-01-01

    Endogenous indole-3-acetic acid (IAA) was found in axenically cultured gametophytes of the leafy liverwort, Plagiochila arctica Bryhn and Kaal., by high-performance liquid chromatography with electrochemical detection. Identification of the methylated auxin was confirmed by gas chromatography-mass spectrometry. Addition of 57 micromolar IAA to cultures increased relative production of ethylene. This is the first definitive (gas chromatography-mass spectrometry) demonstration of the natural occurrence of IAA in a bryophyte. PMID:16664164

  19. Education and production. Chicken manure methanogenesis. 1. Selective inhibition of acetate conversion to methane

    SciTech Connect

    Dosoretz, C.; Lamed, R.

    1987-01-01

    Thermophilic (55 C) methanogenesis of chicken manure was examined after prolonged acclimatization procedures. Unusual steady state parameters were obtained in quasi-continuous operations: volatile solids = 24 to 96 g/L, retention time = 5 to 20 days, in which methane was continuously formed (.5 to .7/L.L/day), H/sub 2/ was not present, but acetate (19 to 222 mM), other fatty acids, and ammonia nitrogen (800 to 2,830 mg/L) levels were very high. Tracer (2-(/sup 14/C) acetate) studies showed that acetate accumulation resulted from inhibition of acetate conversion to methane. Enumeration of H/sub 2/-oxidizing methanogenic populations as well as acetate-degrading methanogens indicated adequate populations in chicken manure relative to cow manure. Thus, measurement of acetate degradation activities indicated its inhibition, whereas bacterial enumeration studies indicated no lack of methanogenic bacterial populations. These findings are in disagreement with the uninhibited fast rate of aceticlastic methanogenesis in cow manure. Therefore, it may be concluded that the methanogenic populations are unchanged, but their capacity to decarboxylate acetate is somehow blocked, which would lead to concomittant accumulation of acetate in addition to the formation of CO/sub 2/ and H/sub 2//CO/sub 2/-derived methane as the major fermentation end products. (Refs. 33).

  20. Acetate Dissimilation and Assimilation in Mycobacterium tuberculosis Depend on Carbon Availability

    PubMed Central

    Rücker, Nadine; Billig, Sandra; Bücker, René; Jahn, Dieter; Wittmann, Christoph

    2015-01-01

    ABSTRACT Mycobacterium tuberculosis persists inside granulomas in the human lung. Analysis of the metabolic composition of granulomas from guinea pigs revealed that one of the organic acids accumulating in the course of infection is acetate (B. S. Somashekar, A. G. Amin, C. D. Rithner, J. Troudt, R. Basaraba, A. Izzo, D. C. Crick, and D. Chatterjee, J Proteome Res 10:4186–4195, 2011, doi:http://dx.doi.org/10.1021/pr2003352), which might result either from metabolism of the pathogen or might be provided by the host itself. Our studies characterize a metabolic pathway by which M. tuberculosis generates acetate in the cause of fatty acid catabolism. The acetate formation depends on the enzymatic activities of Pta and AckA. Using actyl coenzyme A (acetyl-CoA) as a substrate, acetyl-phosphate is generated and finally dephosphorylated to acetate, which is secreted into the medium. Knockout mutants lacking either the pta or ackA gene showed significantly reduced acetate production when grown on fatty acids. This effect is even more pronounced when the glyoxylate shunt is blocked, resulting in higher acetate levels released to the medium. The secretion of acetate was followed by an assimilation of the metabolite when other carbon substrates became limiting. Our data indicate that during acetate assimilation, the Pta-AckA pathway acts in concert with another enzymatic reaction, namely, the acetyl-CoA synthetase (Acs) reaction. Thus, acetate metabolism might possess a dual function, mediating an overflow reaction to release excess carbon units and resumption of acetate as a carbon substrate. IMPORTANCE During infection, host-derived lipid components present the major carbon source at the infection site. β-Oxidation of fatty acids results in the formation of acetyl-CoA. In this study, we demonstrate that consumption of fatty acids by Mycobacterium tuberculosis activates an overflow mechanism, causing the pathogen to release excess carbon intermediates as acetate. The Pta

  1. Understanding Palladium Acetate from a User Perspective.

    PubMed

    Carole, William A; Colacot, Thomas J

    2016-06-01

    The behavior of palladium acetate is reviewed with respect to its synthesis, characterization, structure (in both solution and solid state), and activation pathways. In addition, comparisons of catalytic activities between pure palladium acetate and two common byproducts, Pd3 (OAc)5 (NO2 ) and polymeric [Pd(OAc)2 ]n , typically present in commercially available material are reviewed. Hence, this minireview serves as a concise guide for the users of palladium acetate from both academia and industry. PMID:27125630

  2. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  3. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  4. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... sodium sulfate and sodium bicarbonate. (b) The ingredient meets the specifications of the Food Chemicals... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3...

  5. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... sodium sulfate and sodium bicarbonate. (b) The ingredient meets the specifications of the Food Chemicals... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3...

  6. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... sodium sulfate and sodium bicarbonate. (b) The ingredient meets the specifications of the Food Chemicals... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3...

  7. GLOBAL ASSIGNMENT AND EXTENSION OF MILLIMETER- AND SUBMILLIMETER-WAVE SPECTRAL DATABASE OF {sup 13}C{sub 1}-METHYL FORMATE (H{sup 13}COOCH{sub 3}) IN THE GROUND AND FIRST EXCITED STATES

    SciTech Connect

    Carvajal, M.; Kleiner, I.

    2010-10-15

    A compilation of the available spectroscopic millimeter- and submillimeter-wave data of the ground and first excited states of {sup 13}C{sub 1}-methyl formate (H{sup 13}COOCH{sub 3}) has been carried out. The exhaustive analysis of the available transition lines of H{sup 13}COOCH{sub 3} has led to the assignment of 7457 spectral lines by means of a global fit of 45 parameters, using the Rho-Axis Method and the BELGI-Cs code, with a resulting unitless standard deviation of 0.57. Over 1600 lines are included for the first time in the fit. In addition, the line strengths of spectral lines are also calculated using the most recent experimental measurement of the electric dipole moment. In conclusion, the present study represents a notable improvement with respect to previous H{sup 13}COOCH{sub 3} spectral analyses. Therefore, the better accuracy of the present analysis may help the future identification of new H{sup 13}COOCH{sub 3} lines in the interstellar and circumstellar media, and may contribute to decrease some of the spectral confusion due to these species in astronomical surveys.

  8. A stability-indicating HPLC method for medroxyprogesterone acetate in bulk drug and injection formulation.

    PubMed

    Burana-Osot, Jankana; Ungboriboonpisal, Sooksri; Sriphong, Lawan

    2006-03-18

    A stability-indicating HPLC assay method has been developed and validated for medroxyprogesterone acetate (MPA) in bulk drug and injectable suspension. An isocratic RP-HPLC was achieved on a Hichrom C(18) column (150 mm x 4.6mm i.d., 5 microm) utilizing a mobile phase of methanol 0.020 M acetate buffer pH 5 (65:35, v/v) and a photodiode array detector at 245 nm. The stress testing of MPA was carried out under acidic and alkaline hydrolysis, and oxidation conditions. MPA was well resolved from its degradation products, a main related substance (megestrol acetate) and two preservatives (methyl paraben and propyl paraben) with the resolution >or=2. The proposed method was validated for selectivity, linearity, accuracy, precision and solution stability. The method was found to be suitable for the quality control of MPA in bulk drug and injections as well as the stability-indicating studies. PMID:16242876

  9. Natural abundances of carbon isotopes in acetate from a coastal marine sediment

    NASA Technical Reports Server (NTRS)

    Blair, N. E.; Martens, C. S.; Des Marais, D. J.

    1987-01-01

    Measurements of the natural abundances of carbon isotopes were made in acetate samples isolated from the anoxic marine sediment of Cape Lookout Bight, North Carolina. The typical value of the total acetate carbon isotope ratio (delta 13C) was -16.1 +/- 0.2 per mil. The methyl and carboxyl groups were determined to be -26.4 +/- 0.3 and -6.0 +/- 0.3 per mil, respectively, for one sample. The isotopic composition of the acetate is thought to have resulted from isotopic discriminations that occurred during the cycling of that molecule. Measurements of this type, which have not been made previously in the natural environment, may provide information about the dominant microbial pathways in anoxic sediments as well as the processes that influence the carbon isotopic composition of biogenic methane from many sources.

  10. Molecular Active Sites in Heterogeneous Ir-La/C-Catalyzed Carbonylation of Methanol to Acetates.

    PubMed

    Kwak, Ja Hun; Dagle, Robert; Tustin, Gerald C; Zoeller, Joseph R; Allard, Lawrence F; Wang, Yong

    2014-02-01

    We report that when Ir and La halides are deposited on carbon, exposure to CO spontaneously generates a discrete molecular heterobimetallic structure, containing an Ir-La covalent bond that acts as a highly active, selective, and stable heterogeneous catalyst for the carbonylation of methanol to produce acetic acid. This catalyst exhibits a very high productivity of ∼1.5 mol acetyl/mol Ir·s with >99% selectivity to acetyl (acetic acid and methyl acetate) without detectable loss in activity or selectivity for more than 1 month of continuous operation. The enhanced activity can be mechanistically rationalized by the presence of La within the ligand sphere of the discrete molecular Ir-La heterobimetallic structure, which acts as a Lewis acid to accelerate the normally rate-limiting CO insertion in Ir-catalyzed carbonylation. Similar approaches may provide opportunities for attaining molecular (single site) behavior similar to homogeneous catalysis on heterogeneous surfaces for other industrial applications. PMID:26276610

  11. The Key to Acetate: Metabolic Fluxes of Acetic Acid Bacteria under Cocoa Pulp Fermentation-Simulating Conditions

    PubMed Central

    Adler, Philipp; Frey, Lasse Jannis; Berger, Antje; Bolten, Christoph Josef; Hansen, Carl Erik

    2014-01-01

    Acetic acid bacteria (AAB) play an important role during cocoa fermentation, as their main product, acetate, is a major driver for the development of the desired cocoa flavors. Here, we investigated the specialized metabolism of these bacteria under cocoa pulp fermentation-simulating conditions. A carefully designed combination of parallel 13C isotope labeling experiments allowed the elucidation of intracellular fluxes in the complex environment of cocoa pulp, when lactate and ethanol were included as primary substrates among undefined ingredients. We demonstrate that AAB exhibit a functionally separated metabolism during coconsumption of two-carbon and three-carbon substrates. Acetate is almost exclusively derived from ethanol, while lactate serves for the formation of acetoin and biomass building blocks. Although this is suboptimal for cellular energetics, this allows maximized growth and conversion rates. The functional separation results from a lack of phosphoenolpyruvate carboxykinase and malic enzymes, typically present in bacteria to interconnect metabolism. In fact, gluconeogenesis is driven by pyruvate phosphate dikinase. Consequently, a balanced ratio of lactate and ethanol is important for the optimum performance of AAB. As lactate and ethanol are individually supplied by lactic acid bacteria and yeasts during the initial phase of cocoa fermentation, respectively, this underlines the importance of a well-balanced microbial consortium for a successful fermentation process. Indeed, AAB performed the best and produced the largest amounts of acetate in mixed culture experiments when lactic acid bacteria and yeasts were both present. PMID:24837393

  12. Techniques in protein methylation.

    PubMed

    Lee, Jaeho; Cheng, Donghang; Bedford, Mark T

    2004-01-01

    Proteins can be methylated on the side-chain nitrogens of arginine and lysine residues or on carboxy-termini. Protein methylation is a way of subtly changing the primary sequence of a peptide so that it can encode more information. This common posttranslational modification is implicated in the regulation of a variety of processes including protein trafficking, transcription and protein-protein interactions. In this chapter, we will use the arginine methyltransferases to illustrate different approaches that have been developed to assess protein methylation. Both in vivo and in vitro methylation techniques are described, and the use of small molecule inhibitors of protein methylation will be demonstrated. PMID:15173617

  13. Structural Analysis of a Ni-Methyl Species in Methyl-Coenzyme M Reductase from Methanothermobacter marburgensis

    SciTech Connect

    Cedervall, Peder E.; Dey, Mishtu; Li, Xianghui; Sarangi, Ritimukta; Hedman, Britt; Ragsdale, Stephen W.; Wilmot, Carrie M.

    2012-02-15

    We present the 1.2 {angstrom} resolution X-ray crystal structure of a Ni-methyl species that is a proposed catalytic intermediate in methyl-coenzyme M reductase (MCR), the enzyme that catalyzes the biological formation of methane. The methyl group is situated 2.1 {angstrom} proximal of the Ni atom of the MCR coenzyme F{sub 430}. A rearrangement of the substrate channel has been posited to bring together substrate species, but Ni(III)-methyl formation alone does not lead to any observable structural changes in the channel.

  14. Extractive fermentation of acetic acid

    SciTech Connect

    Busche, R.M.

    1991-12-31

    In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium: Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newer Clostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent extraction to recover the product. Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of the ethanol fermentation are poor, but near the biological limits of the organisms involved. Conversely, C. thermoaceticum is a thermophilic anaerobe that operates at high fermentation rates on glucose at neutral pH to produce acetate salts directly in substantially quantitative yields. However, it is severely inhibited by product, which restricts concentration to a dilute 20 g/L. An improved Acetobacter system operating with recycled cells at 50 g/L appears capable of producing acid at $0.38/lb, as compared with a $0.29/lb price for synthetic acid. However, this system has only a limited margin for process improvement. The present Clostridium system cannot compete, since the required selling price would be $0.42/lb. However, if the organism could be adapted to tolerate higher product concentrations at acid pH, selling price could be reduced to $0.22/lb, or about 80% of the price of synthetic acid.

  15. Regioselective Alcoholysis of Silychristin Acetates Catalyzed by Lipases ‡

    PubMed Central

    Vavříková, Eva; Gavezzotti, Paolo; Purchartová, Kateřina; Fuksová, Kateřina; Biedermann, David; Kuzma, Marek; Riva, Sergio; Křen, Vladimír

    2015-01-01

    A panel of lipases was screened for the selective acetylation and alcoholysis of silychristin and silychristin peracetate, respectively. Acetylation at primary alcoholic group (C-22) of silychristin was accomplished by lipase PS (Pseudomonas cepacia) immobilized on diatomite using vinyl acetate as an acetyl donor, whereas selective deacetylation of 22-O-acetyl silychristin was accomplished by Novozym 435 in methyl tert-butyl ether/n-butanol. Both of these reactions occurred without diastereomeric discrimination of silychristin A and B. Both of these enzymes were found to be capable to regioselective deacetylation of hexaacetyl silychristin to afford penta-, tetra- and tri-acetyl derivatives, which could be obtained as pure synthons for further selective modifications of the parent molecule. PMID:26016503

  16. The in vivo glucocorticoid and antiglucocorticoid actions of medroxyprogesterone acetate.

    PubMed

    Guthrie, G P; John, W J

    1980-11-01

    The in vivo glucocorticoid actions of medroxyprogesterone acetate [6 alpha-methyl-17-acetoxy-pregn-4-ene-3,20-dione (MPA)] were assessed in intact prepubertal female Wistar rats using five simultaneous assays: plasma glucose, plasma corticosterone, hepatic glycogen content, hepatic tyrosine aminotransferase activity, and croton oil-induced ear inflammation. Antiglucocorticoid acitivity was measured through interference by MPA with the glucocorticoid effect of a standard 5-microgram dose of dexamethasone in these same assays. The glucocorticoid activity of MPA was evident from suppression of corticosterone and ear inflammation and stimulation of tyrosine aminotransferase activity. The antiglucocorticoid activity of MPA was detected through inhibition of basal and dexamethasone-stimulated hepatic glycogen and partial reversal of the suppression of ear inflammation by dexamethasone. The progestational steroid MPA was thus found to have assay-specific glucocorticoid and antiglucocorticoid actions and may have a potential use in the treatment of some states of glucocorticoid excess. PMID:6107239

  17. The Rotational Spectrum and Conformational Structures of Methyl Valerate

    NASA Astrophysics Data System (ADS)

    Nguyen, Ha Vinh Lam; Stahl, Wolfgang

    2015-06-01

    Methyl valerate, C4H9COOCH3, belongs to the class of fruit esters, which play an important role in nature as odorants of different fruits, flowers, and wines. A sufficient explanation for the structure-odor relation of is not available. It is known that predicting the odor of a substance is not possible by knowing only its chemical formula. A typical example is the blueberry- or pine apple-like odor of ethyl isovalerate while its isomers ethyl valerate and isoamyl acetate smell like green apple and banana, respectively. Obviously, not only the composition but also the molecular structures are not negligible by determining the odor of a substance. Gas phase structures of fruit esters are thus important for a first step towards the determination of structure-odor relation since the sense of smell starts from gas phase molecules. For this purpose, a combination of microwave spectroscopy and quantum chemical calculations (QCCs) is an excellent tool. Small esters often have sufficient vapor pressure to be transferred easily in the gas phase for a rotational study but already contain a large number of atoms which makes them too big for classical structure determination by isotopic substitution and requires nowadays a comparison with the structures optimized by QCCs. On the other hand, the results from QCCs have to be validated by the experimental values. About the internal dynamics, the methoxy methyl group -COOCH3 of methyl acetate shows internal rotation with a barrier of 424.581(56) wn. A similar barrier height of 429.324(23) wn was found in methyl propionate, where the acetyl group is extended to the propionyl group. The investigation on methyl valerate fits well in this series of methyl alkynoates. In this talk, the structure of the most energetic favorable conformer as well as the internal rotation shown by the methoxy methyl group will be reported. It could be confirmed that the internal rotation barrier of the methoxy methyl group remains by longer alkyl chain.

  18. 40 CFR Appendix A to Part 439 - Tables

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... Isopropyl acetate n-Amyl acetate n-Butyl acetate Methyl formate Tetrahydrofuran 1 Ethers. Isopropyl ether... Methyl formate Isopropyl ether Tetrahydrofuran 1 1,2-dichloroethane o-Dichlorobenzene 1 These...

  19. 40 CFR Appendix A to Part 439 - Tables

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    .... Isopropyl acetate n-Amyl acetate n-Butyl acetate Methyl formate Tetrahydrofuran 1 Ethers. Isopropyl ether... Methyl formate Isopropyl ether Tetrahydrofuran 1 1,2-dichloroethane o-Dichlorobenzene 1 These...

  20. Effects of methyl p-hydroxybenzoate (methyl paraben) on Ca2+ concentration and histamine release in rat peritoneal mast cells

    PubMed Central

    Fukugasako, Sanae; Ito, Shinichi; Ikemoto, Yoshimi

    2003-01-01

    Mechanisms of methyl p-hydroxybenzoate (methyl paraben) action in allergic reactions were investigated by measuring the intracellular Ca2+ concentration ([Ca2+]i) and histamine release in rat peritoneal mast cells (RPMCs). In the presence or absence of extracellular Ca2+, methyl paraben (0.1–10 mM) increased [Ca2+]i, in a concentration-dependent manner. Under both the conditions, methyl paraben alone did not evoke histamine release. In RPMCs pretreated with a protein kinase C (PKC) activator (phorbol 12-myristate 13-acetate (PMA) 3 and 10 nM), methyl paraben (0.3–3 mM) induced histamine release. However, a high concentration (10 mM) of the agent did not increase the histamine release. U73122 (0.1 and 0.5 μM), an inhibitor of phospholipase C (PLC), significantly inhibited the methyl paraben-induced histamine release in PMA-pretreated RPMCs. U73343 (0.5 μM), an inactive analogue of U73122, did not inhibit the histamine release caused by methyl paraben. In Ca2+-free solution, PLC inhibitors (U73122 0.1 and 0.5 μM, D609 1–10 μM) inhibited the methyl paraben-induced increase in [Ca2+]i, whereas U73343 (0.5 μM) did not. Xestospongin C (2–20 μM) and 2 aminoethoxydiphenyl borate (30 and 100 μM), blockers of the inositol 1,4,5-trisphosphate (IP3) receptor, inhibited the methyl paraben-induced increase in [Ca2+]i in Ca2+-free solution. In conclusion, methyl paraben causes an increase in [Ca2+]i, which may be due to release of Ca2+ from storage sites by IP3 via activation of PLC in RPMCs. In addition, methyl paraben possibly has some inhibitory effects on histamine release via unknown mechanisms. PMID:12770943

  1. All natural cellulose acetate-Lemongrass essential oil antimicrobial nanocapsules.

    PubMed

    Liakos, Ioannis L; D'autilia, Francesca; Garzoni, Alice; Bonferoni, Cristina; Scarpellini, Alice; Brunetti, Virgilio; Carzino, Riccardo; Bianchini, Paolo; Pompa, Pier Paolo; Athanassiou, Athanassia

    2016-08-30

    Nanocapsules and nanoparticles play an essential role in the delivery of pharmaceutical agents in modern era, since they can be delivered in specific tissues and cells. Natural polymers, such as cellulose acetate, are becoming very important due to their availability, biocompatibility, absence of toxicity and biodegradability. In parallel, essential oils are having continuous growth in biomedical applications due to the inherent active compounds that they contain. A characteristic example is lemongrass oil that has exceptional antimicrobial properties. In this work, nanocapsules of cellulose acetate with lemongrass oil were developed with the solvent/anti-solvent method with resulting diameter tailored between 95 and 185nm. Various physico-chemical and surface analysis techniques were employed to investigate the formation of the nanocapsules. These all-natural nanocapsules found to well bioadhere to mucous membranes and to have very good antimicrobial properties at little concentrations against Escherichia coli and Staphylococcus aureus. PMID:26827919

  2. 21 CFR 556.380 - Melengestrol acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Melengestrol acetate. 556.380 Section 556.380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Tolerances for Residues of New Animal Drugs § 556.380 Melengestrol acetate. A tolerance of 25 parts...

  3. 21 CFR 556.380 - Melengestrol acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Melengestrol acetate. 556.380 Section 556.380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Tolerances for Residues of New Animal Drugs § 556.380 Melengestrol acetate. A tolerance of 25 parts...

  4. 21 CFR 556.380 - Melengestrol acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Melengestrol acetate. 556.380 Section 556.380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Tolerances for Residues of New Animal Drugs § 556.380 Melengestrol acetate. A tolerance of 25 parts...

  5. 21 CFR 556.380 - Melengestrol acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Melengestrol acetate. 556.380 Section 556.380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Tolerances for Residues of New Animal Drugs § 556.380 Melengestrol acetate. A tolerance of 25 parts...

  6. Manufacturing Ethyl Acetate From Fermentation Ethanol

    NASA Technical Reports Server (NTRS)

    Rohatgi, Naresh K.; Ingham, John D.

    1991-01-01

    Conceptual process uses dilute product of fermentation instead of concentrated ethanol. Low-concentration ethanol, extracted by vacuum from fermentation tank, and acetic acid constitutes feedstock for catalytic reaction. Product of reaction goes through steps that increases ethyl acetate content to 93 percent by weight. To conserve energy, heat exchangers recycle waste heat to preheat process streams at various points.

  7. 21 CFR 173.228 - Ethyl acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the specifications of the Food Chemicals Codex, 1 (Ethyl Acetate; p. 372, 3d Ed., 1981), which are... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethyl acetate. 173.228 Section 173.228 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR...

  8. Expression and specificity profile of the major acetate transporter AcpA in Aspergillus nidulans.

    PubMed

    Sá-Pessoa, Joana; Amillis, Sotiris; Casal, Margarida; Diallinas, George

    2015-03-01

    AcpA has been previously characterized as a high-affinity transporter essential for the uptake and use of acetate as sole carbon source in Aspergillus nidulans. Here, we follow the expression profile of AcpA and define its substrate specificity. AcpA-mediated acetate transport is detected from the onset of conidiospore germination, peaks at the time of germ tube emergence, and drops to low basal levels in germlings and young mycelia, where a second acetate transporter is also becoming apparent. AcpA activity also responds to acetate presence in the growth medium, but is not subject to either carbon or nitrogen catabolite repression. Short-chain monocarboxylates (benzoate, formate, butyrate and propionate) inhibit AcpA-mediated acetate transport with apparent inhibition constants (Ki) of 16.89±2.12, 9.25±1.01, 12.06±3.29 and 1.44±0.13mM, respectively. AcpA is also shown not to be directly involved in ammonia export, as proposed for its Saccharomyces cerevisiae homologue Ady2p. In the second part of this work, we search for the unknown acetate transporter expressed in mycelia, and for other transporters that might contribute to acetate uptake. In silico analysis, genetic construction of relevant null mutants, and uptake assays, reveal that the closest AcpA homologue (AN1839), named AcpB, is the 'missing' secondary acetate transporter in mycelia. We also identify two major short-chain carboxylate (lactate, succinate, pyruvate and malate) transporters, named JenA (AN6095) and JenB (AN6703), which however are not involved in acetate uptake. This work establishes a framework for further exploiting acetate and carboxylate transport in filamentous ascomycetes. PMID:25708319

  9. Pharmacokinetics and drug interactions of eslicarbazepine acetate.

    PubMed

    Bialer, Meir; Soares-da-Silva, Patricio

    2012-06-01

    Eslicarbazepine acetate (ESL) is a novel once-daily antiepileptic drug (AED) approved in Europe since 2009 that was found to be efficacious and well tolerated in a phase III clinical program in adult patients with partial onset seizures previously not controlled with treatment with one to three AEDs, including carbamazepine (CBZ). ESL shares with CBZ and oxcarbazepine (OXC) the dibenzazepine nucleus bearing the 5-carboxamide substitute, but is structurally different at the 10,11 position. This molecular variation results in differences in metabolism, preventing the formation of toxic epoxide metabolites such as carbamazepine-10,11-epoxide. Unlike OXC, which is metabolized to both eslicarbazepine and (R)-licarbazepine, ESL is extensively converted to eslicarbazepine. The systemic exposure to eslicarbazepine after ESL oral administration is approximately 94% of the parent dose, with minimal exposure to (R)-licarbazepine and OXC. After ESL oral administration, the effective half-life (t(1/2,eff) ) of eslicarbazepine was 20-24 h, which is approximately two times longer than its terminal half-life (t(1/2)). At clinically relevant doses (400-1,600 mg/day) ESL has linear pharmacokinetics (PK) with no effects of gender or moderate liver impairment. However, because eslicarbazepine is eliminated primarily (66%) by renal excretion, dose adjustment is recommended for patients with renal impairment. Eslicarbazepine clearance is induced by phenobarbital, phenytoin, and CBZ and it dose-dependently decreases plasma exposure of oral contraceptive and simvastatin. PMID:22612290

  10. Biodegradable cellulose acetate nanofiber fabrication via electrospinning.

    PubMed

    Christoforou, Theopisti; Doumanidis, Charalabos

    2010-09-01

    Nanofiber manufacturing is one of the key advancements in nanotechnology today. Over the past few years, there has been a tremendous growth of research activities to explore electrospinning for nanofiber formation from a rich variety of materials. This quite simple and cost effective process operates on the principle that the solution is extracted under the action of a high electric field. Once the voltage is sufficiently high, a charged jet is ejected following a complicated looping trajectory. During its travel, the solvent evaporates leaving behind randomly oriented nanofibers accumulated on the collector. The combination of their nanoscale dimensionality, high surface area, porosity, flexibility and superior strength makes the electrospun fibers suitable for several value-added applications, such as filters, protecting clothes, high performance structures and biomedical devices. In this study biodegradable cellulose acetate (CA) nanofibrous membranes were produced using electrospinning. The device utilized consisted of a syringe equipped with a metal needle, a microdialysis pump, a high voltage supply and a collector. The morphology of the yielded fibers was determined using SEM. The effect of various parameters, including electric field strength, tip-to-collector distance, solution feed rate and composition on the morphological features of the electrospun fibers was examined. The optimum operating conditions for the production of uniform, non-beaded fibers with submicron diameter were also explored. The biodegradable CA nanofiber membranes are suitable as tissue engineering scaffolds and as reinforcements of biopolymer matrix composites in foils by ultrasonic welding methods. PMID:21133179

  11. Genome-guided analysis of physiological and morphological traits of the fermentative acetate oxidizer Thermacetogenium phaeum

    PubMed Central

    2012-01-01

    Background Thermacetogenium phaeum is a thermophilic strictly anaerobic bacterium oxidizing acetate to CO2 in syntrophic association with a methanogenic partner. It can also grow in pure culture, e.g., by fermentation of methanol to acetate. The key enzymes of homoacetate fermentation (Wood-Ljungdahl pathway) are used both in acetate oxidation and acetate formation. The obvious reversibility of this pathway in this organism is of specific interest since syntrophic acetate oxidation operates close to the energetic limitations of microbial life. Results The genome of Th. phaeum is organized on a single circular chromosome and has a total size of 2,939,057 bp. It comprises 3.215 open reading frames of which 75% could be assigned to a gene function. The G+C content is 53.88 mol%. Many CRISPR sequences were found, indicating heavy phage attack in the past. A complete gene set for a phage was found in the genome, and indications of phage action could also be observed in culture. The genome contained all genes required for CO2 reduction through the Wood-Ljungdahl pathway, including two formyl tetrahydrofolate ligases, three carbon monoxide dehydrogenases, one formate hydrogenlyase complex, three further formate dehydrogenases, and three further hydrogenases. The bacterium contains a menaquinone MQ-7. No indications of cytochromes or Rnf complexes could be found in the genome. Conclusions The information obtained from the genome sequence indicates that Th. phaeum differs basically from the three homoacetogenic bacteria sequenced so far, i.e., the sodium ion-dependent Acetobacterium woodii, the ethanol-producing Clostridium ljungdahlii, and the cytochrome-containing Moorella thermoacetica. The specific enzyme outfit of Th. phaeum obviously allows ATP formation both in acetate formation and acetate oxidation. PMID:23259483

  12. Degradation of methyl bromide in anaerobic sediments

    USGS Publications Warehouse

    Oremland, R.S.; Miller, L.G.; Strohmaler, F.E.

    1994-01-01

    Methyl bromide (MeBr) was anaerobically degraded in saltmarsh sediments after reaction with sulfide. The product of this nucleophilic substitution reaction was methanethiol, which underwent further chemical and bacterial reactions to form dimethyl sulfide. These two gases appeared transiently during sediment incubations because they were metabolized by methanogenic and sulfate-reducing bacteria. A second, less significant reaction of MeBr was the exchange with chloride, forming methyl chloride, which was also susceptible to attack by sulfide. Incubation of 14C-labeled methyl iodide as an analogue of MeBr resulted in the formation of 14CH4 and 14CO2 and also indicated that sulfate-reducing bacteria as well as methanogens metabolized the methylated sulfur intermediates. These results suggest that exposed sediments with abundant free sulfide, such as coastal salt-marshes, may constitute a sink for atmospheric MeBr.

  13. Electrocyclic [1,5] hydrogen shift in the thermal elimination kinetics of phenyl acetate and p-tolyl acetate in the gas phase: a density functional theory study

    NASA Astrophysics Data System (ADS)

    Marquez, Edgar; Maldonado, Alexis; Rosas, Felix; Ramirez, Beatriz; Cordova-Sintjago, Tania; Chuchani, Gabriel

    2014-02-01

    The kinetics and mechanisms of thermal decomposition of phenyl acetate and p-tolyl acetate in the gas phase were studied by means of electronic structure calculations using density functional theory methods: B3LYP/6-31G(d,p), B3LYP/6-31++G(d,p), B3PW91/6-31G(d,p), B3PW91/6-31++G(d,p), MPW1PW91/6-31G(d,p), MPW1PW91/6-31++G(d,p), PBE/6-31G(d,p) and PBE/6-31++G(d,p). Two possible mechanisms have been considered: mechanism A is a stepwise process involving electrocyclic [1,5] hydrogen shift to eliminate ketene through concerted six-membered cyclic transition-state structure, followed by tautomerisation of cyclohexadienone or by 4-methyl cyclohexadienone intermediate to give the corresponding phenol. Mechanism B is a one-step concerted [1,3] hydrogen shift through a four-membered cyclic transition-state geometry, to produce ketene and phenol or p-cresol. Theoretical calculations showed reasonable agreement with experimental activation parameters when using the Perdew, Burke and Ernserhof (PBE)functional, through the stepwise [1,5] hydrogen-shift mechanism. For mechanism B, large deviation for the entropy of activation was observed. No experimental data were available for p-tolyl acetate; however, theoretical calculations showed similar results to phenyl acetate, thus supporting the stepwise mechanism for both phenyl acetate and p-tolyl acetate.

  14. Enzymatic production of biodiesel from microalgal oil using ethyl acetate as an acyl acceptor.

    PubMed

    Alavijeh, Razieh Shafiee; Tabandeh, Fatemeh; Tavakoli, Omid; Karkhane, Aliasghar; Shariati, Parvin

    2015-01-01

    Microalgae have become an important source of biomass for biodiesel production. In enzymatic transesterification reaction, the enzyme activity is decreased in presence of alcohols. The use of different acyl acceptors such as methyl/ethyl acetate is suggested as an alternative and effective way to overcome this problem. In this study, ethyl acetate was used for the first time in the enzymatic production of biodiesel by using microalga, Chlorella vulgaris, as a triglyceride source. Enzymatic conversion of such fatty acids to biodiesel was catalyzed by Novozym 435 as an efficient immobilized lipase which is extensively used in biodiesel production. The best conversion yield of 66.71% was obtained at the ethyl acetate to oil molar ratio of 13:1 and Novozym 435 concentration of 40%, based on the amount of oil, and a time period of 72 h at 40℃. The results showed that ethyl acetate have no adverse effect on lipase activity and the biodiesel amount was not decreased even after seven transesterification cycles, so ethyl acetate has a great potential to be substituted for short-chain alcohols in transesterification reaction. PMID:25742923

  15. Effects of [alpha]-methyl group substitution on the dimerization products of furan-based o-quinodimethanes

    SciTech Connect

    Leung, M.K.; Trahanovsky, W.S. Ames Lab., IA )

    1995-01-25

    3-Ethylidene-2-methylene-(12), 2-ethylidene-3-methylene-(13), and 2,3-diethylidene-(14)2,3-dihydrofurans were prepared by fluoride induced 1,4-conjugative elimination of trimethylsilyl acetate from the appropriate precursors. The [sup 1]H NMR spectra of these furan-based o-quinodimethanes were obtained and the dimerization products of each were studied. It was found that a methyl group at the 3-methylene position retards the rate of dimerization which is consistent with the previously proposed dimerization mechanism, the two-step mechanism involving rate-determining formation of a diradical intermediate followed by rapid cyclization of the diradical. 25 refs., 8 figs., 6 tabs.

  16. Competing Formate- and Carbon Dioxide-Utilizing Prokaryotes in an Anoxic Methane-Emitting Fen Soil▿†

    PubMed Central

    Hunger, Sindy; Schmidt, Oliver; Hilgarth, Maik; Horn, Marcus A.; Kolb, Steffen; Conrad, Ralf; Drake, Harold L.

    2011-01-01

    Methanogenesis in wetlands is dependent on intermediary substrates derived from the degradation of biopolymers. Formate is one such substrate and is stimulatory to methanogenesis and acetogenesis in anoxic microcosms of soil from the fen Schlöppnerbrunnen. Formate dissimilation also yields CO2 as a potential secondary substrate. The objective of this study was to resolve potential differences between anaerobic formate- and CO2-utilizing prokaryotes of this fen by stable isotope probing. Anoxic soil microcosms were pulsed daily with low concentrations of [13C]formate or 13CO2 (i.e., [13C]bicarbonate). Taxa were evaluated by assessment of 16S rRNA genes, mcrA (encoding the alpha-subunit of methyl-coenzyme M reductase), and fhs (encoding formyltetrahydrofolate synthetase). Methanogens, acetogens, and formate-hydrogen lyase-containing taxa appeared to compete for formate. Genes affiliated with Methanocellaceae, Methanobacteriaceae, Acetobacteraceae, and Rhodospirillaceae were 13C enriched (i.e., labeled) in [13C]formate treatments, whereas genes affiliated with Methanosarcinaceae, Conexibacteraceae, and Solirubrobacteraceae were labeled in 13CO2 treatments. [13C]acetate was enriched in [13C]formate treatments, but labeling of known acetogenic taxa was not detected. However, several phylotypes were affiliated with acetogen-containing taxa (e.g., Sporomusa). Methanosaetaceae-affiliated methanogens appeared to participate in the consumption of acetate. Twelve and 58 family-level archaeal and bacterial 16S rRNA phylotypes, respectively, were detected, approximately half of which had no isolated representatives. Crenarchaeota constituted half of the detected archaeal 16S rRNA phylotypes. The results highlight the unresolved microbial diversity of the fen Schlöppnerbrunnen, suggest that differing taxa competed for the same substrate, and indicate that Methanocellaceae, Methanobacteriaceae, Methanosarcinaceae, and Methanosaetaceae were linked to the production of methane

  17. Quantification of syntrophic acetate-oxidizing microbial communities in biogas processes.

    PubMed

    Westerholm, Maria; Dolfing, Jan; Sherry, Angela; Gray, Neil D; Head, Ian M; Schnürer, Anna

    2011-08-01

    Changes in communities of syntrophic acetate-oxidizing bacteria (SAOB) and methanogens caused by elevated ammonia levels were quantified in laboratory-scale methanogenic biogas reactors operating at moderate temperature (37°C) using quantitative polymerase chain reaction (qPCR). The experimental reactor was subjected to gradually increasing ammonia levels (0.8-6.9 g NH4 (+) -N l(-1) ), whereas the level of ammonia in the control reactor was kept low (0.65-0.90 g NH4 (+) -N l(-1) ) during the entire period of operation (660 days). Acetate oxidation in the experimental reactor, indicated by increased production of (14) CO2 from acetate labelled in the methyl carbon, occurred when ammonia levels reached 5.5 and 6.9 g NH4 (+) -N l(-1) . Syntrophic acetate oxidizers targeted by newly designed qPCR primers were Thermacetogenium phaeum, Clostridium ultunense, Syntrophaceticus schinkii and Tepidanaerobacter acetatoxydans. The results showed a significant increase in abundance of all these bacteria except T. phaeum in the ammonia-stressed reactor, coincident with the shift to syntrophic acetate oxidation. As the abundance of the bacteria increased, a simultaneous decrease was observed in the abundance of aceticlastic methanogens from the families Methanosaetaceae and Methanosarcinaceae. qPCR analyses of sludge from two additional high ammonia processes, in which methane production from acetate proceeded through syntrophic acetate oxidation (reactor SB) or through aceticlastic degradation (reactor DVX), demonstrated that SAOB were significantly more abundant in the SB reactor than in the DVX reactor. PMID:23761313

  18. Quantification of syntrophic acetate-oxidizing microbial communities in biogas processes

    PubMed Central

    Westerholm, Maria; Dolfing, Jan; Sherry, Angela; Gray, Neil D; Head, Ian M; Schnürer, Anna

    2011-01-01

    Changes in communities of syntrophic acetate-oxidizing bacteria (SAOB) and methanogens caused by elevated ammonia levels were quantified in laboratory-scale methanogenic biogas reactors operating at moderate temperature (37°C) using quantitative polymerase chain reaction (qPCR). The experimental reactor was subjected to gradually increasing ammonia levels (0.8–6.9 g NH4+-N l−1), whereas the level of ammonia in the control reactor was kept low (0.65–0.90 g NH4+-N l−1) during the entire period of operation (660 days). Acetate oxidation in the experimental reactor, indicated by increased production of 14CO2 from acetate labelled in the methyl carbon, occurred when ammonia levels reached 5.5 and 6.9 g NH4+-N l−1. Syntrophic acetate oxidizers targeted by newly designed qPCR primers were Thermacetogenium phaeum, Clostridium ultunense, Syntrophaceticus schinkii and Tepidanaerobacter acetatoxydans. The results showed a significant increase in abundance of all these bacteria except T. phaeum in the ammonia-stressed reactor, coincident with the shift to syntrophic acetate oxidation. As the abundance of the bacteria increased, a simultaneous decrease was observed in the abundance of aceticlastic methanogens from the families Methanosaetaceae and Methanosarcinaceae. qPCR analyses of sludge from two additional high ammonia processes, in which methane production from acetate proceeded through syntrophic acetate oxidation (reactor SB) or through aceticlastic degradation (reactor DVX), demonstrated that SAOB were significantly more abundant in the SB reactor than in the DVX reactor. PMID:23761313

  19. Reaction engineering analysis of hydrogenotrophic production of acetic acid by Acetobacterium woodii.

    PubMed

    Demler, Martin; Weuster-Botz, Dirk

    2011-02-01

    Great interest has emerged in biological CO₂-fixing processes in the context of current climate change discussions. One example for such a process is the hydrogenotrophic production of acetic acid by anaerobic microorganisms. Acetogenic microorganisms make use of carbon dioxide in the presence of hydrogen to produce acetic acid and biomass. In order to establish a process for the hydrogenotrophic production of acetic acid, the formation of acetate by Acetobacterium woodii was studied in a batch-operated stirred-tank bioreactor at different hydrogen partial pressures (pH₂) in the gas phase. The volumetric productivity of the batch processes increased with increasing hydrogen partial pressure. A maximum of the volumetric productivity of 7.4 g(acetate) L⁻¹ day⁻¹ was measured at a pH₂ of 1,700 mbar. At this pH(2) a final acetate concentration of 44 g L⁻¹ was measured after a process time of 11 days, if the pH was controlled at pH 7.0 (average cell density of 1.1 g L⁻¹ cell dry weight). The maximum cell specific actetate productivity was 6.9 g(acetate) g(cdw)⁻¹ day⁻¹ under hydrogenotrophic conditions. PMID:20830677

  20. Oxidation and methylation of dissolved elemental mercury by anaerobic bacteria

    NASA Astrophysics Data System (ADS)

    Hu, Haiyan; Lin, Hui; Zheng, Wang; Tomanicek, Stephen J.; Johs, Alexander; Feng, Xinbin; Elias, Dwayne A.; Liang, Liyuan; Gu, Baohua

    2013-09-01

    Methylmercury is a neurotoxin that poses significant health risks to humans. Some anaerobic sulphate- and iron-reducing bacteria can methylate oxidized forms of mercury, generating methylmercury. One strain of sulphate-reducing bacteria (Desulfovibrio desulphuricans ND132) can also methylate elemental mercury. The prevalence of this trait among different bacterial strains and species remains unclear, however. Here, we compare the ability of two strains of the sulphate-reducing bacterium Desulfovibrio and one strain of the iron-reducing bacterium Geobacter to oxidize and methylate elemental mercury in a series of laboratory incubations. Experiments were carried out under dark, anaerobic conditions, in the presence of environmentally relevant concentrations of elemental mercury. We report differences in the ability of these organisms to oxidize and methylate elemental mercury. In line with recent findings, we show that D.desulphuricans ND132 can both oxidize and methylate elemental mercury. We find that the rate of methylation of elemental mercury is about one-third the rate of methylation of oxidized mercury. We also show that Desulfovibrio alaskensis G20 can oxidize, but not methylate, elemental mercury. Geobacter sulphurreducens PCA is able to oxidize and methylate elemental mercury in the presence of cysteine. We suggest that the activity of methylating and non-methylating bacteria may together enhance the formation of methylmercury in anaerobic environments.

  1. Oxidation and methylation of dissolved elemental mercury by anaerobic bacteria

    SciTech Connect

    Hu, Haiyan; Lin, Hui; Zheng, Wang; Tomanicek, Stephen J; Johs, Alexander; Feng, Xinbin; Elias, Dwayne A; Liang, Liyuan; Gu, Baohua

    2013-08-04

    Methylmercury is a neurotoxin that poses significant health risks to humans. Some anaerobic sulphate- and iron-reducing bacteria can methylate oxidized forms of mercury, generating methylmercury1-4. One strain of sulphate-reducing bacteria (Desulfovibrio desulfuricans ND132) can also methylate elemental mercury5. The prevalence of this trait among different bacterial strains and species remains unclear, however. Here, we compare the ability of two strains of the sulphate-reducing bacterium Desulfovibrio and one strain of the iron-reducing bacterium Geobacter to oxidise and methylate elemental mercury in a series of laboratory incubations. Experiments were carried out under dark, anaerobic conditions, in the presence of environmentally-relevant concentrations of elemental mercury. We report differences in the ability of these organisms to oxidise and methylate elemental mercury. In line with recent findings5, we show that Desulfovibrio desulfuricans ND132 can both oxidise and methylate elemental mercury. However, the rate of methylation of elemental mercury is only about one third the rate of methylation of oxidized mercury. We also show that Desulfovibrio alaskensis G20 can oxidise, but not methylate, elemental mercury. Geobacter sulfurreducens PCA is able to oxidise and methylate elemental mercury in the presence of cysteine. We suggest that the activity of methylating and non-methylating bacteria may together enhance the formation of methylmercury in anaerobic environments.

  2. Influence of 13C isotopic labeling location of 13C DNP of acetate using TEMPO free radical

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Lumata, Lloyd

    2015-03-01

    Dynamic nuclear polarization (DNP) via the dissolution method enhances the liquid-state magnetic resonance (NMR or MRI) signals of insensitive nuclear spins by at least 10,000-fold. The basis for all these signal enhancements at room temperature is the polarization transfer from the electrons to nuclear spins at cryogenic temperature and high magnetic field. In this work, we have studied the influence of the location of 13C isotopic labeling on the DNP of sodium acetate at 3.35 T and 1.4 K using a wide ESR linewidth free radical 4-oxo-TEMPO. The carbonyl [1-13C]acetate spins produced a polarization level that is almost twice that of the methyl [2-13C]acetate spins. On the other hand, the polarization of the methyl 13C spins doubled to reach the level of [1-13C]acetate when the methyl group was deuterated. Meanwhile, the solid-state nuclear relaxation of these samples are the same and do not correlate with the polarization levels. These behavior implies that the nuclear relaxation for these samples is dominated by the contribution from the free radicals and the polarization levels can be explained by a thermodynamic picture of DNP.

  3. Transient formation of the oxo-iron(IV) porphyrin radical cation during the reaction of iron(III) tetrakis-5,10,15,20-(N-methyl-4-pyridyl)porphyrin with hydrogen peroxide in aqueous solution.

    PubMed

    Saha, Tapan Kumar; Karmaker, Subarna; Tamagake, Keietsu

    2003-01-01

    The reaction of iron(III) tetrakis-5,10,15,20-(N-methyl-4-pyridyl)porphyrin (Fe(III)TMPyP) with hydrogen peroxide (H(2)O(2)) and the catalytic activity of the reaction intermediates on the luminescent peroxidation of luminol in aqueous solution were studied by using a double-mixing stopped-flow system. The observed luminescence intensities showed biphasic decay depending on the conditions. The initial flashlight decayed within <1 s followed by a sustained emission for more than 30 s. Computer deconvolution of the time-resolved absorption spectra under the same conditions revealed that the initial flashlight appeared during the formation of the oxo-iron(IV) porphyrin, TMPyPFe(IV) = O, which is responsible for the sustained emission. The absorption spectra 0.0-0.5 s did not reproduce well by a simple combination of the two spectra of Fe(III)TMPyP and TMPyPFe(IV) = O, indicating that transient species was formed at the initial stage. Addition of uric acid (UA) caused a significant delay in the initiation of the luminol emission as well as in the formation of the TMPyPFe(IV) = O. Both of them were completely diminished in the presence of UA equimolar with H(2)O(2), while mannitol had no effect at all. The delay of the light emission as well as the appearance of TMPyPFe(IV) = O was directly proportional to the [UA](0) but other kinetic profiles were not changed significantly. Based on these observations and the kinetic analysis, we confirmed the involvement of the oxo-iron(IV) porphyrin radical cation, (TMPyP)(.+)Fe(IV) = O, as an obligatory intermediate in the rate-determining step of the overall reaction, Fe(III)TMPyP + H(2)O(2) --> TMPyPFe(IV) = O, with a rate constant of k = 4.3 x 10(4)/mol/L/s. The rate constants for the reaction between the (TMPyP)(.+)Fe(IV) = O and luminol, and between the TMPyPFe(IV) = O and luminol were estimated to be 3.6 x 10(6)/mol/L/s and 1.31 x 10(4)/mol/L/s, respectively. PMID:12701092

  4. Acetic anhydride: an intermediate analogue in the acyl-exchange reaction of citramalate lyase.

    PubMed

    Buckel, W

    1976-04-15

    1. Reactivation of deacetyl citramalate lyase by acetic anhydride proceeds through an enzyme-anhydride complex prior to actual acetylation. The reaction is inhibited by citramalate which is competitive with acetic anhydride. 2. A corresponding complex is an intermediate in the carboxymethylation of deacetyl enzyme by iodoacetate. However, the inhibition of this reaction by S-citramalate appears to be non-competitive with iodoacetate. 3. The results lead to the conclusion that acetic anhydride can be regarded as a structural analogue of citramalic acetic anhydride, the proposed intermediate in the acyl exchange reaction on citramalate lyase. 4. The formation of 6-citryl thiolester from the 1-thiolester via the cyclic citric anhydride provides a chemicla model for enzymic acyl exchange. 5. The data suggest that anhydrides are of general importance in acyl exchange reactions of thiolesters. PMID:1278157

  5. The pharmacology of nomegestrol acetate.

    PubMed

    Ruan, Xiangyan; Seeger, Harald; Mueck, Alfred O

    2012-04-01

    Nomegestrol acetate (NOMAC) is a 19-norprogesterone derivative with high biological activity at the progesterone receptor, a weak anti-androgenic effect, but with no binding to estrogen, glucocorticoid or mineralocorticoid receptors. At dosages of 1.5mg/day or more, NOMAC effectively suppresses gonadotropic activity and ovulation in women of reproductive age. Hemostasis, lipids and carbohydrate metabolism remain largely unchanged. In normal and cancerous human breast cells, NOMAC has shown favorable effects on estrogen metabolism. Like natural progesterone (but in contrast to some other synthetic progestogens), it does not appear stimulate the proliferation of cancerous breast cells. While there has been some experience of the use of NOMAC in combination with estrogens as a hormone replacement therapy, most of the data on the compound are reported in the context of its inclusion as a component of a new contraceptive pill comprising 2.5mg NOMAC combined with 1.5mg estradiol. Because of its strong endometrial efficacy, and due to its high antigonadotropic activity and long elimination half-life (about 50h), the contraceptive efficacy of the new pill is maintained even when dosages are missed. Furthermore, for the first time with a monophasic 24/4 regimen containing estradiol, cyclical stability can be achieved comparable with that obtained using pills containing ethinyl estradiol and progestogens like levonorgestrel or drospirenone. The addition of NOMAC to estradiol means that the beneficial effects of estrogen are not lost, which is of especial importance in relation to the cardiovascular system. On the basis both of its pharmacology and of studies performed during the development of the NOMAC/estradiol pill, involving some 4000 women in total, good long-term tolerability can be expected for NOMAC, although its safety profile is still to be fully ascertained, as the clinical endpoint studies are yet to be completed. PMID:22364709

  6. Conversion to eslicarbazepine acetate monotherapy

    PubMed Central

    French, Jacqueline; Jacobson, Mercedes P.; Pazdera, Ladislav; Gough, Mallory; Cheng, Hailong; Grinnell, Todd; Blum, David

    2016-01-01

    Objective: To assess the efficacy and safety of eslicarbazepine acetate (ESL) monotherapy. Methods: This post hoc pooled analysis of 2 randomized double-blind studies (093-045 and -046) included adults with partial-onset seizures medically uncontrolled by 1 or 2 antiepileptic drugs (AEDs). Following the baseline period (8 weeks), eligible patients were randomized 2:1 to receive ESL 1,600 mg or 1,200 mg once daily for 18 weeks; the primary endpoint was study exit by meeting predefined exit criteria (signifying worsening seizure control). In each study, treatment was considered effective if the upper 95% confidence limit for exit rate was lower than the historical control threshold (65.3%). Results: Pooled exit rates were as follows: ESL 1,600 mg = 20.6% (95% confidence interval: 15.6%–26.8%); ESL 1,200 mg = 30.8% (23.0%–40.5%). Use of 2 baseline AEDs or rescue medication, US location, epilepsy duration ≥20 years, and higher maximum baseline seizure frequency were associated with higher exit risks. Median percent reductions in standardized seizure frequency between baseline and the 18-week double-blind period were as follows: ESL 1,600 mg = 43.2%; ESL 1,200 mg = 35.7%; baseline carbamazepine use was associated with smaller reductions. Safety profiles were similar between ESL doses. Conclusions: Exit rates for ESL monotherapy (1,600 mg and 1,200 mg once daily) were lower than the historical control threshold, irrespective of baseline AED use and region, with no additional safety concerns identified. Clinical factors and location clearly influence treatment responses in conversion-to-monotherapy trials. Classification of evidence: This pooled analysis provides Class IV evidence that for adults with medically uncontrolled partial-onset seizures, ESL monotherapy is well tolerated and effective. PMID:26911639

  7. Folate deficiency affects histone methylation.

    PubMed

    Garcia, Benjamin A; Luka, Zigmund; Loukachevitch, Lioudmila V; Bhanu, Natarajan V; Wagner, Conrad

    2016-03-01

    that the bound THF serves to protect the FAD class of histone demethylases from the destructive effects of formaldehyde generation by formation of 5,10-methylene-THF. We present pilot data showing that decreased folate in livers as a result of dietary folate deficiency is associated with increased levels of methylated lysine 4 of histone 3. This can be a result of decreased LSD1 activity resulting from the decreased folate available to scavenge the formaldehyde produced at the active site caused by the folate deficiency. Because LSD1 can regulate gene expression this suggests that folate may play a more important role than simply serving as a carrier of one-carbon units and be a factor in other diseases associated with low folate. PMID:26880641

  8. Computational insights into CdSe quantum dots' interactions with acetate ligands.

    PubMed

    Tamukong, Patrick K; Peiris, Wadumesthrige D N; Kilina, Svetlana

    2016-07-27

    Using density functional theory (DFT) and time-dependent DFT (TDDFT), we investigate the effects of carboxylate groups on the electronic and optical properties of CdSe quantum dots (QDs). We specifically focus on the mechanisms of the binding of the acetate anion to the QD surface with and without excess of Cd(2+) cations. Our calculations show that the most stable ligated conformations are those where an acetate is attached to extra Cd(2+) ion forming a [Cd(2+)(CH3COO(-))] at the QD's surface, while also accompanied by an acetate attached nearby at the surface balancing the overall neutral charge of the system. In contrast, formation of a neutral metal-acetate complex [Cd(2+)(CH3COO(-))2] at the QD surface is found to be the least energetically preferable. A strength of the QD-ligand interaction depends on the solvent, the facet of the QD to which the ligands are attached, and the binding mode - with the bridging mode found to be the most stable conformation for both acetate and cadmium acetate ligands. The cadmium acetate ligands introduce electron trap states at the edge of the conduction band - unoccupied orbitals predominately localized on Cd(2+) ion - that are extremely sensitive to the ligand position and the solvent polarity. Polar solvents like acetonitrile delocalize the electronic density over the entire system and, thus, eliminate trap states. As a result, mixed passivation of the CdSe QDs by pairs of cadmium acetate and acetate ligands provides optimal optical properties with minimal contributions of the ligand-related trap states and optically bright lowest energy transitions. PMID:27406268

  9. Unusal pattern of product inhibition: batch acetic acid fermentation

    SciTech Connect

    Bar, R.; Gainer, J.L.; Kirwan, D.J.

    1987-04-20

    The limited tolerance of microorganisms to their metabolic products results in inhibited growth and product formation. The relationship between the specific growth rate, micro, and the concentration of an inhibitory product has been described by a number of mathematical models. In most cases, micro was found to be inversely proportional to the product concentration and invariably the rate of substrate utilization followed the same pattern. In this communication, the authors report a rather unusual case in which the formation rate of a product, acetic acid, increased with a decreasing growth rate of the microorganism, Acetobacter aceti. Apparently, a similar behavior was mentioned in a review report with respect to Clostridium thermocellum in a batch culture but was not published in the freely circulating literature. The fermentation of ethanol to acetic acid, C/sub 2/H/sub 5/OH + O/sub 2/ = CH/sub 3/COOH + H/sub 2/O is clearly one of the oldest known fermentations. Because of its association with the commercial production of vinegar it has been a subject of extensive but rather technically oriented studies. Suprisingly, the uncommon uncoupling between the inhibited microbial growth and the product formation appears to have been unnoticed. 13 references.

  10. Isotopic composition of Murchison organic compounds: Intramolecular carbon isotope fractionation of acetic acid. Simulation studies of cosmochemical organic syntheses

    NASA Technical Reports Server (NTRS)

    Yuen, G. U.; Cronin, J. R.; Blair, N. E.; Desmarais, D. J.; Chang, S.

    1991-01-01

    Recently, in our laboratories, samples of Murchison acetic acid were decarboxylated successfully and the carbon isotopic composition was measured for the methane released by this procedure. These analyses showed significant differences in C-13/C-12 ratios for the methyl and carboxyl carbons of the acetic acid molecule, strongly suggesting that more than one carbon source may be involved in the synthesis of the Murchison organic compounds. On the basis of this finding, laboratory model systems simulating cosmochemical synthesis are being studied, especially those processes capable of involving two or more starting carbon sources.

  11. [Accidental methyl alcohol poisoning].

    PubMed

    Xiao, J H

    1990-05-01

    An accidental poisoning due to drinking methyl alcohol in Chaoyang county is reported, analysing the accident. The poison came from the "retail white spirit" which was contaminated with methyl alcohol. Twenty-nine persons drank the wine, fourteen of them died, two of them became blind. After drinking this "retail white spirit" the drinkers showed symptoms of vertigo, headache, weakness, vomiting, night sweat, dyspnea and blurring of vision etc. within 6-120 hours. On examining the remaining spirit, we found the content of methyl alcohol to be between 16.6 and 40.69 g/100 ml. Some of the patients' urine and blood also contained methyl alcohol. We reckoned that each one of the twenty patients had taken more than 27 g of methyl alcohol and each of the ten dead drank more than 40 ml of the alcohol. PMID:2253526

  12. Complexation of thorium(IV) with acetate at variable temperatures.

    PubMed

    Rao, Linfeng; Zhang, Zhicheng; Zanonato, PierLuigi; Di Bernardo, Plinio; Bismondo, Arturo; Clark, Sue B

    2004-09-21

    The complexation between Th(IV) and acetate in 1.05 mol kg(-1) NaClO4 was studied at variable temperatures (10, 25, 40, 55 and 70 degrees C). The formation constants of five successive complexes, Th(Ac)j(4-j)+ where Ac = CH3COO- and j = 1-5, and the molar enthalpies of complexation were determined by potentiometry and calorimetry. Extended X-ray absorption fine structure spectroscopy (EXAFS) provided additional information on the complexes in solution. The effect of temperature on the stability of the complexes is discussed in terms of the electrostatic model. PMID:15349159

  13. Clostridium thermosaccharolyticum strain deficient in acetate production

    SciTech Connect

    Rothstein, D.M.

    1986-01-01

    A mutant of Clostridium thermosaccharolyticum that is blocked in acetate production was isolated after treatment with nitrosoguanidine and selection for fluoroacetate resistance. The mutant produced more ethanol than the parent strain did.

  14. Mafenide acetate allergy presenting as recurrent chondritis.

    PubMed

    Pickus, Evan J; Lionelli, Gerald T; Charles, E Woodall; Korentager, Richard A

    2002-02-01

    Acute chondritis has a strong predilection for recurrence. Mafenide acetate has been implicated in causing reactions that mimic this condition; however, these hypersensitivity reactions lack fever, fluctuance, and pain. The authors report a case of mafenide acetate allergy presenting as recurrent chondritis in a patient who had previously been treated successfully for this condition. In this patient, the allergic response resolved within 3 days after cessation of mafenide acetate. If unappreciated, it may have led to unnecessary operative intervention. Therefore, auricular edema and erythema, without fever, fluctuance, and pain, must be recognized by surgeons as a possible mafenide acetate allergy and must be considered in the differential diagnosis for patients who present with recurrent acute suppurative chondritis. PMID:11910229

  15. Nomegestrol acetate/estradiol: in oral contraception.

    PubMed

    Yang, Lily P H; Plosker, Greg L

    2012-10-01

    Nomegestrol acetate/estradiol is a combined oral contraceptive with approval in many countries. This fixed-dose combination tablet contains nomegestrol acetate, a highly selective progestogen, and estradiol, a natural estrogen. It is the first monophasic combined oral contraceptive to contain estradiol, and is taken in 28-day cycles, consisting of 24 active therapy days with 4 placebo days (i.e. 24/4-day cycles). In two large, 1-year, randomized, open-label, multicentre, phase III trials in healthy adult women (aged 18-50 years), nomegestrol acetate/estradiol was at least as effective as drospirenone/ethinylestradiol as contraceptive therapy, as the pregnancy rates in women aged 18-35 years (primary efficacy population) in terms of the Pearl Index (primary endpoint) were numerically lower with nomegestrol acetate/estradiol, although the between-group difference was not statistically significant. In both trials, nomegestrol acetate/estradiol was given in a 24/4-day cycle, and drospirenone/ethinylestradiol was given in a 21/7-day cycle. The criteria for using condoms in case of forgotten doses were less stringent in the nomegestrol acetate/estradiol group than in the drospirenone/ethinylestradiol group. Nomegestrol acetate/estradiol therapy for up to 1 year was generally well tolerated in healthy adult women, with an acceptable tolerability profile in line with that expected for a combined oral contraceptive. The most commonly reported adverse events were acne and abnormal withdrawal bleeding (most often shorter, lighter or absent periods). Overall, compared with drospirenone/ethinylestradiol, nomegestrol acetate/estradiol appeared to be associated with less favourable acne-related outcomes, and shorter, lighter or absent periods. PMID:22950535

  16. Methanogenesis from acetate: a nonmethanogenic bacterium from an anaerobic acetate enrichment.

    PubMed

    Ward, D M; Mah, R A; Kaplan, I R

    1978-06-01

    A methanogenic acetate enrichment was initiated by inoculation of an acetate-mineral salts medium with domestic anaerobic digestor sludge and maintained by weekly transfer for 2 years. The enrichment culture contained a Methanosarcina and several obligately anaerobic nonmethanogenic bacteria. These latter organisms formed varying degrees of association with the Methanosarcina, ranging from the nutritionally fastidious gram-negative rod called the satellite bacterium to the nutritionally nonfastidious Eubacterium limosum. The satellite bacterium had growth requirements for amino acids, a peptide, a purine base, vitamin B12, and other B vitamins. Glucose, mannitol, starch, pyruvate, cysteine, lysine, leucine, isoleucine, arginine, and asparagine stimulated growth and hydrogen production. Acetate was neither incorporated nor metabolized by the satellite organism. Since acetate was the sole organic carbon source in the enrichment culture, organism(s) which metabolize acetate (such as the Methanosarcina) must produce substrates and growth factors for associated organisms which do not metabolize acetate. PMID:677881

  17. An Experimental and Kinetic Modeling Study of Methyl Decanoate Combustion

    SciTech Connect

    Sarathy, S M; Thomson, M J; Pitz, W J; Lu, T

    2010-02-19

    Biodiesel is typically a mixture of long chain fatty acid methyl esters for use in compression ignition engines. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This research study presents new combustion data for methyl decanoate in an opposed-flow diffusion flame. An improved detailed chemical kinetic model for methyl decanoate combustion is developed, which serves as the basis for deriving a skeletal mechanism via the direct relation graph method. The novel skeletal mechanism consists of 648 species and 2998 reactions. This mechanism well predicts the methyl decanoate opposed-flow diffusion flame data. The results from the flame simulations indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene.

  18. VvMJE1 of the grapevine (Vitis vinifera) VvMES Methylesterase family encodes for Methyl Jasmonate Esterase and has a role in stress response

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The known members of the plant methyl esterase (MES) family catalyze hydrolysis of a C-O ester linkage of methyl esters of several phytohormones including indole-3-acetic acid, salicylic acid, and jasmonic acid. The genome of grapevine (Vitis vinifera) was found to contain 15 MES genes, designated V...

  19. VvMJE1 of the grapevine (Vitis vinifera) VvMES methylesterase family encodes for methyl jasmonate esterase and has a role in stress response

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The known members of the plant methyl esterase (MES) family catalyze hydrolysis of a C-O ester linkage of methyl esters of several phytohormones including indole-3-acetic acid, salicylic acid, and jasmonic acid. The genome of grapevine (Vitis vinifera) was found to contain 15 MES genes, designated V...

  20. 40 CFR 180.318 - 4-(2-Methyl-4-chlorophenoxy) butyric acid; tolerance for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...)butanoic acid, and its metabolite MCPA, (4-chloro-2-methylphenoxy)acetic acid, in or on the following food... acid; tolerance for residues. 180.318 Section 180.318 Protection of Environment ENVIRONMENTAL... FOOD Specific Tolerances § 180.318 4-(2-Methyl-4-chlorophenoxy) butyric acid; tolerance for...

  1. Adrenocortical suppression in cats given megestrol acetate.

    PubMed

    Chastain, C B; Graham, C L; Nichols, C E

    1981-12-01

    Megestrol acetate was given orally to 8 cats at a dose of 2.5 mg every other day for 2 weeks and to 8 cats at a dose of 5.0 mg every day for 2 weeks. Four cats were designated nontreated controls. Pre-ACTH-stimulated plasma concentrations of cortisol (hydrocortisone) and ACTH-stimulated cortisol and tolerance to large-dose glucose infusion (IV) were determined on each of the 20 cats given megestrol acetate. Cats were restrained with acepromazine maleate and ketamine hydrochloride during blood sample collection and large-dose glucose infusion. Adrenocortical function and tolerance to large-dose glucose infusion were reevaluated for 4 weeks--after 1st and 2nd weeks of megestrol acetate treatment of the treated groups, and after 1st and 2nd weeks when treatment was stopped (ie, experiment weeks 3 and 4). Each week a cat from the control group and 2 cats from the 2 treated groups were selected to determine the changes occurring during the experiment for that week; after collection of plasma samples, each week's 5 selected cats were euthanatized and necropsied. Significant impairment of adrenocortical function and alteration of adrenocortical morphology occurred with both treated groups. The most severe adrenocortical alterations occurred in the cats 1 week after megestrol acetate was no longer given (ie, experiment week 3). Megestrol acetate-induced adrenocortical suppression contributed to the death of 1 cat. It was concluded that if stress occurs to cats on treatment or soon after treatment with megestrol acetate, glucocorticoids should be supplemented. The effects of megestrol acetate on glucose tolerance were overshadowed by the unforeseen intolerance caused by chemical restraint with acepromazine maleate and ketamine hydrochloride. PMID:6280517

  2. Preabsorptive Metabolism of Sodium Arsenate by Anaerobic Microbiota of Mouse Cecum Forms a Variety of Methylated and Thiolated Arsenicals

    EPA Science Inventory

    The conventional scheme for arsenic methylation accounts for methylated oxyarsenical production but not for thioarsenical formation. Here, we report that in vitro anaerobic microbiota of mouse cecum converts arsenate into oxy- and thio- arsenicals. Besides methylarsonic acid (MMA...

  3. Tetrazole acetic acid: Tautomers, conformers, and isomerization

    NASA Astrophysics Data System (ADS)

    Araujo-Andrade, C.; Reva, I.; Fausto, R.

    2014-02-01

    Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric modifications, 1H- and 2H-, depending on the position of the annular hydrogen atom. Two-dimensional potential energy surfaces (PESs) of TAA were theoretically calculated at the MP2/6-311++G(d,p) level, for each tautomer. Four and six symmetry-unique minima were located on these PESs, for 1H- and 2H-TAA, respectively. The energetics of the detected minima was subsequently refined by calculations at the QCISD level. Two 1H- and three 2H-conformers fall within the 0-8 kJ mol-1 energy range and should be appreciably populated at the sublimation temperature (˜330 K). Observation of only one conformer for each tautomer (1ccc and 2pcc) is explained in terms of calculated barriers to conformational rearrangements. All conformers with the cis O=COH moiety are separated by low barriers (less than 10 kJ mol-1) and collapse to the most stable 1ccc (1H-) and 2pcc (2H-) forms during deposition of the matrix. On the trans O=COH surfaces, the relative energies are very high (between 12 and 27 kJ mol-1). The trans forms are not thermally populated at the sublimation conditions and were not detected in matrices. One high-energy form in each tautomer, 1cct (1H-) and 2pct (2H-), was found to differ from the most stable form only by rotation of the OH group and separated from other forms by high barriers. This opened a perspective for their stabilization in a matrix. 1cct and 2pct were generated in the matrices selectively by means of narrow-band near-infrared (NIR) irradiations of the samples at 6920 and 6937 cm-1, where the first OH stretching overtone vibrations of 1ccc and 2pcc occur. The

  4. Tetrazole acetic acid: tautomers, conformers, and isomerization.

    PubMed

    Araujo-Andrade, C; Reva, I; Fausto, R

    2014-02-14

    Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric modifications, 1H- and 2H-, depending on the position of the annular hydrogen atom. Two-dimensional potential energy surfaces (PESs) of TAA were theoretically calculated at the MP2/6-311++G(d,p) level, for each tautomer. Four and six symmetry-unique minima were located on these PESs, for 1H- and 2H-TAA, respectively. The energetics of the detected minima was subsequently refined by calculations at the QCISD level. Two 1H- and three 2H-conformers fall within the 0-8 kJ mol(-1) energy range and should be appreciably populated at the sublimation temperature (∼330 K). Observation of only one conformer for each tautomer (1ccc and 2pcc) is explained in terms of calculated barriers to conformational rearrangements. All conformers with the cis O=COH moiety are separated by low barriers (less than 10 kJ mol(-1)) and collapse to the most stable 1ccc (1H-) and 2pcc (2H-) forms during deposition of the matrix. On the trans O=COH surfaces, the relative energies are very high (between 12 and 27 kJ mol(-1)). The trans forms are not thermally populated at the sublimation conditions and were not detected in matrices. One high-energy form in each tautomer, 1cct (1H-) and 2pct (2H-), was found to differ from the most stable form only by rotation of the OH group and separated from other forms by high barriers. This opened a perspective for their stabilization in a matrix. 1cct and 2pct were generated in the matrices selectively by means of narrow-band near-infrared (NIR) irradiations of the samples at 6920 and 6937 cm(-1), where the first OH stretching overtone vibrations of 1ccc and 2pcc occur

  5. Tetrazole acetic acid: Tautomers, conformers, and isomerization

    SciTech Connect

    Araujo-Andrade, C.; Reva, I. Fausto, R.

    2014-02-14

    Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric modifications, 1H- and 2H-, depending on the position of the annular hydrogen atom. Two-dimensional potential energy surfaces (PESs) of TAA were theoretically calculated at the MP2/6-311++G(d,p) level, for each tautomer. Four and six symmetry-unique minima were located on these PESs, for 1H- and 2H-TAA, respectively. The energetics of the detected minima was subsequently refined by calculations at the QCISD level. Two 1H- and three 2H-conformers fall within the 0–8 kJ mol{sup −1} energy range and should be appreciably populated at the sublimation temperature (∼330 K). Observation of only one conformer for each tautomer (1ccc and 2pcc) is explained in terms of calculated barriers to conformational rearrangements. All conformers with the cis O=COH moiety are separated by low barriers (less than 10 kJ mol{sup −1}) and collapse to the most stable 1ccc (1H-) and 2pcc (2H-) forms during deposition of the matrix. On the trans O=COH surfaces, the relative energies are very high (between 12 and 27 kJ mol{sup −1}). The trans forms are not thermally populated at the sublimation conditions and were not detected in matrices. One high-energy form in each tautomer, 1cct (1H-) and 2pct (2H-), was found to differ from the most stable form only by rotation of the OH group and separated from other forms by high barriers. This opened a perspective for their stabilization in a matrix. 1cct and 2pct were generated in the matrices selectively by means of narrow-band near-infrared (NIR) irradiations of the samples at 6920 and 6937 cm{sup −1}, where the first OH stretching overtone

  6. The Role of Electrolyte Upon the SEI Formation Characteristics and Low Temperature Performance of Lithium-Ion Cells With Graphite Anodes

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Greenbaum, S.; Surampudi, S.

    2000-01-01

    Quarternary lithium-ion battery electrolyte solutions containing ester co-solvents in mixtures of carbonates have been demonstrated to have high conductivity at low temperatures (< -20C). However, in some cases the presence of such co-solvents does not directly translate into improved low temperature cell performance, presumably due to the formation of ionically resistive surface films on carbonaceous anodes. In order to understand this behavior, a number of lithium-graphite cells have been studied containing electrolytes with various ester co-solvents, including methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP), and ethyl butyrate (EB). The charge/discharge characterization of these cells indicates that the higher molecular weight esters result in electrolytes which possess superior low temperature performance in contrast to the lower molecular weight ester-containing solutions, even though these solutions display lower conductivity values.

  7. Smyd2 controls cytoplasmic lysine methylation of Hsp90 and myofilament organization

    PubMed Central

    Donlin, Laura T.; Andresen, Christian; Just, Steffen; Rudensky, Eugene; Pappas, Christopher T.; Kruger, Martina; Jacobs, Erica Y.; Unger, Andreas; Zieseniss, Anke; Dobenecker, Marc-Werner; Voelkel, Tobias; Chait, Brian T.; Gregorio, Carol C.; Rottbauer, Wolfgang; Tarakhovsky, Alexander; Linke, Wolfgang A.

    2012-01-01

    Protein lysine methylation is one of the most widespread post-translational modifications in the nuclei of eukaryotic cells. Methylated lysines on histones and nonhistone proteins promote the formation of protein complexes that control gene expression and DNA replication and repair. In the cytoplasm, however, the role of lysine methylation in protein complex formation is not well established. Here we report that the cytoplasmic protein chaperone Hsp90 is methylated by the lysine methyltransferase Smyd2 in various cell types. In muscle, Hsp90 methylation contributes to the formation of a protein complex containing Smyd2, Hsp90, and the sarcomeric protein titin. Deficiency in Smyd2 results in the loss of Hsp90 methylation, impaired titin stability, and altered muscle function. Collectively, our data reveal a cytoplasmic protein network that employs lysine methylation for the maintenance and function of skeletal muscle. PMID:22241783

  8. Acetate Transport and Utilization in the Rat Brain

    PubMed Central

    Deelchand, Dinesh K.; Shestov, Alexander A.; Koski, Dee M.; Uğurbil, Kâmil; Henry, Pierre-Gilles

    2009-01-01

    Acetate, a glial-specific substrate, is an attractive alternative to glucose for the study of neuronal-glial interactions. The present study investigates the kinetics of acetate uptake and utilization in the rat brain in vivo during infusion of [2-13C]acetate using NMR spectroscopy. When plasma acetate concentration was increased, the rate of brain acetate utilization (CMRace) increased progressively and reached close to saturation for plasma acetate concentration > 2-3 mM, whereas brain acetate concentration continued to increase. The Michaelis-Menten constant for brain acetate utilization ( KMutil=0.01±0.14mM) was much smaller than for acetate transport through the blood-brain barrier ( KMt=4.18±0.83mM). The maximum transport capacity of acetate through the blood-brain barrier ( Vmaxt=0.96±0.18μmol/g/min) was nearly two-fold higher than the maximum rate of brain acetate utilization ( Vmaxutil=0.50±0.08μmol/g/min). We conclude that, under our experimental conditions, brain acetate utilization is saturated when plasma acetate concentrations increase above 2-3 mM. At such high plasma acetate concentration, the rate-limiting step for glial acetate metabolism is not the blood-brain barrier, but occurs after entry of acetate into the brain. PMID:19393008

  9. Selective enhancement of autotrophic acetate production with genetically modified Acetobacterium woodii.

    PubMed

    Straub, Melanie; Demler, Martin; Weuster-Botz, Dirk; Dürre, Peter

    2014-05-20

    Great interest has emerged in the recent past towards the potential of autotrophic acetogenic bacteria for the sustainable production of fuels and chemicals. This group of microorganisms possesses an ancient pathway for the fixation of carbon dioxide in the presence of hydrogen, making them highly attractive for the utilization of gas mixtures as a cheap and abundant carbon and energy source. As more and more genome sequence data of acetogens becomes available, the genetic tools are being developed concomitantly. Here, we demonstrate for the first time the genetic modification of the well-characterized acetogen Acetobacterium woodii. This microorganism selectively produces acetate under autotrophic conditions, but seems to be limited at high acetate concentrations. To increase the carbon flow through the Wood-Ljungdahl pathway and therefore increase the efficiency of CO2 fixation, genes of enzyme groups of this pathway were selectively overexpressed (the four THF-dependent enzymes for the processing of formate as well as phosphotransacetylase and acetate kinase to enhance an ATP-generation step). Acetate production with genetically modified strains was increased in a batch process under pH-controlled reaction conditions in a stirred-tank reactor with continuous sparging of H2 and CO2. Final acetate concentrations of more than 50gL(-1) acetate were thus measured with the recombinant strains at low cell concentrations of 1.5-2gL(-1) dry cell mass in less than four days under autotrophic conditions. PMID:24637370

  10. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  11. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  12. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  13. ENZYMOLOGY OF ARSENIC METHYLATION

    EPA Science Inventory

    Enzymology of Arsenic Methylation

    David J. Thomas, Pharmacokinetics Branch, Experimental Toxicology Division, National
    Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park...

  14. Methyl salicylate overdose

    MedlinePlus

    Deep heating rubs overdose; Oil of wintergreen overdose ... These products contain methyl salicylate: Deep-heating creams used to relieve sore muscles and joints (Ben Gay, Icy Hot) Oil of wintergreen Solutions for vaporizers Other products ...

  15. Total Synthesis of Acetate from CO2: Methyltetrahydrofolate, an Intermediate, and a Procedure for Separation of the Folates

    PubMed Central

    Parker, Donald J.; Wu, Tsai-Feng; Wood, Harland G.

    1971-01-01

    Whole-cell preparations of Clostridium thermoaceticum were exposed to a short pulse of 14CO2 under conditions in which double-labeled acetate was synthesized. Radioactive methyltetrahydrofolate monoglutamate, diglutamate, and triglutamates were isolated from extracts of the cells. The radioactivity was found to be exclusively in the five methyl position. The specific activities of the methyltetrahydrofolate derivatives were very high and were in accord with the proposal that methyltetrahydrofolates are the precursors of the methyl of acetate. A new method of separation of folates employing QAE-Sephadex chromatography and a linear gradient with triethylammonium bicarbonate is presented which completely resolves the common folate monoglutamates and, upon freeze-drying, yields salt-free preparations. PMID:5001869

  16. Amavadin and other vanadium complexes as remarkably efficient catalysts for one-pot conversion of ethane to propionic and acetic acids.

    PubMed

    Kirillova, Marina V; Kuznetsov, Maxim L; da Silva, José A L; Guedes da Silva, Maria Fátima C; Fraústo da Silva, João J R; Pombeiro, Armando J L

    2008-01-01

    Synthetic amavadin Ca[V{ON[CH(CH(3))COO](2)}(2)] and its models Ca[V{ON(CH(2)COO)(2)}(2)] and [VO{N(CH(2)CH(2)O)(3)}], in the presence of K(2)S(2)O(8) in trifluoroacetic acid (TFA), exhibit remarkable catalytic activity for the one-pot carboxylation of ethane to propionic and acetic acids with the former as the main product (overall yields up to 93 %, catalyst turnover numbers (TONs) up to 2.0 x 10(4)). The simpler V complexes [VO(CF(3)SO(3))(2)], [VO(acac)(2)] and VOSO(4) are less active. The effects of various factors, namely, C(2)H(6) and CO pressures, time, temperature, and amounts of catalyst, TFA and K(2)S(2)O(8), have been investigated, and this allowed optimisation of the process and control of selectivity. (13)C-labelling experiments indicated that the formation of acetic acid follows two pathways, the dominant one via oxidation of ethane with preservation of the C--C bond, and the other via rupture of this bond and carbonylation of the methyl group by CO; the C--C bond is retained in the formation of propionic acid upon carbonylation of ethane. The reactions proceed via both C- and O-centred radicals, as shown by experiments with radical traps. On the basis of detailed DFT calculations, plausible reaction mechanisms are discussed. The carboxylation of ethane in the presence of CO follows the sequential formation of C(2)H(5) (*), C(2)H(5)CO(*), C(2)H(5)COO(*) and C(2)H(5)COOH. The C(2)H(5)COO(*) radical is easily formed on reaction of C(2)H(5)CO(*) with a peroxo V catalyst via a V{eta(1)-OOC(O)C(2)H(5)} intermediate. In the absence of CO, carboxylation proceeds by reaction of C(2)H(5) (*) with TFA. For the oxidation of ethane to acetic acid, either with preservation or cleavage of the C-C bond, metal-assisted and purely organic pathways are also proposed and discussed. PMID:18058882

  17. 40 CFR Appendix A to Part 439 - Tables

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... acetate n-Amyl acetate n-Butyl acetate Methyl formate Tetrahydrofuran 1 Ethers. Isopropyl ether Acetone 1... chloride 1 Chlorobenzene Ammonia (aqueous) Diethyl amine Triethyl amine Acetone 1 4-methyl-2-pentanone...

  18. 40 CFR Appendix A to Part 439 - Tables

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... acetate n-Amyl acetate n-Butyl acetate Methyl formate Tetrahydrofuran 1 Ethers. Isopropyl ether Acetone 1... chloride 1 Chlorobenzene Ammonia (aqueous) Diethyl amine Triethyl amine Acetone 1 4-methyl-2-pentanone...

  19. Tested Demonstrations: Buffer Capacity of Various Acetic Acid-Sodium Acetate Systems: A Lecture Experiment.

    ERIC Educational Resources Information Center

    Donahue, Craig J.; Panek, Mary G.

    1985-01-01

    Background information and procedures are provided for a lecture experiment which uses indicators to illustrate the concept of differing buffer capacities by titrating acetic acid/sodium acetate buffers with 1.0 molar hydrochloric acid and 1.0 molar sodium hydroxide. A table with data used to plot the titration curve is included. (JN)

  20. Acetylation of Starch with Vinyl Acetate in Imidazolium Ionic Liquids and Characterization of Acetate Distribution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch was acetylated with vinyl acetate in different 1-butyl-3-methylimidazolium (BMIM) salts as solvent in effort to produce starches with different acetylation patterns. Overall degree of substitution was much higher for basic anions such as acetate and dicyanimide (dca) than for neutral anions ...

  1. 40 CFR 721.10001 - 2-Ethoxyethanol, 2-ethoxyethanol acetate, 2-methoxyethanol, and 2-methoxyethanol acetate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... new uses subject to reporting. (1) The chemical substances identified as 2-ethoxyethanol (CAS No. 110-80-5), 2-ethoxyethanol acetate (CAS No. 111-15-9), 2-methoxyethanol (CAS No. 109-86-4), and 2-methoxyethanol acetate (CAS No. 110-49-6) are subject to reporting under this section for the significant new...

  2. 40 CFR 721.10001 - 2-Ethoxyethanol, 2-ethoxyethanol acetate, 2-methoxyethanol, and 2-methoxyethanol acetate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... new uses subject to reporting. (1) The chemical substances identified as 2-ethoxyethanol (CAS No. 110-80-5), 2-ethoxyethanol acetate (CAS No. 111-15-9), 2-methoxyethanol (CAS No. 109-86-4), and 2-methoxyethanol acetate (CAS No. 110-49-6) are subject to reporting under this section for the significant new...

  3. [Degradation of thiometon in ethyl acetate].

    PubMed

    Satoh, M; Shimokawa, S; Kobata, M; Tanaka, T; Nakanishi, Y

    2001-04-01

    When performing multiresidue analysis of pesticides, the recovery of thiometon was less than 20% from carrots and eggplants, but about 100% from garlic chives and welsh onions. The recovery of thiometon was found to depend on the lot of ethyl acetate. A 2-year-old lot of ethyl acetate caused degradation of thiometon, but a fresh lot of ethyl acetate did not. Analysis showed that ethyl acetate stored for 2 years contained about 5 microL/mL of acetaldehyde. Thiometon was also degraded by acetone or acetonitrile, when acetaldehyde was added to them, in the same manner as by aged ethyl acetate. The fact that the recovery of thiometon from welsh onions was about 100% indicated that some of the mercaptans in allium vegetables may prevent thiometon degradation. Mercaptans such as L-cysteine and 3-mercaptoproionic acid were confirmed to prevent the degradation of thiometon and disulfoton. These findings show that mercaptans may be useful additives for analyzing thiometon and disulfoton. PMID:11486375

  4. Inheritance of Cytosine Methylation.

    PubMed

    Tillo, Desiree; Mukherjee, Sanjit; Vinson, Charles

    2016-11-01

    There are numerous examples of parental transgenerational inheritance that is epigenetic. The informational molecules include RNA, chromatin modifications, and cytosine methylation. With advances in DNA sequencing technologies, the molecular and epigenetic mechanisms mediating these effects are now starting to be uncovered. This mini-review will highlight some of the examples of epigenetic inheritance, the establishment of cytosine methylation in sperm, and recent genomic studies linking sperm cytosine methylation to epigenetic effects on offspring. A recent paper examining changes in diet and sperm cytosine methylation from pools of eight animals each, found differences between a normal diet, a high fat diet, and a low protein diet. However, epivariation between individuals within a group was greater than the differences between groups obscuring any potential methylation changes linked to diet. Learning more about epivariation may help unravel the mechanisms that regulate cytosine methylation. In addition, other experimental and genetic systems may also produce more dramatic changes in the sperm methylome, making it easier to unravel potential transgenerational phenomena. J. Cell. Physiol. 231: 2346-2352, 2016. © 2016 Wiley Periodicals, Inc. PMID:26910768

  5. Relative kinetic measurements of rate coefficients for the gas-phase reactions of Cl atoms and OH radicals with a series of methyl alkyl esters

    NASA Astrophysics Data System (ADS)

    Schütze, Nicole; Zhong, Xiaoyin; Kirschbaum, Stefan; Bejan, Iustinian; Barnes, Ian; Benter, Thorsten

    2010-12-01

    Relative kinetic studies have been performed on the reactions of Cl atoms with a series of methyl alkyl esters in a 405-liter borosilicate glass chamber at (298 ± 3) K and one atmosphere of synthetic air using in situ FTIR spectroscopy to monitor the reactants. Rate coefficients (in units of cm 3 molecule -1 s -1) were determined for the following compounds: methyl acetate (2.48 ± 0.58) × 10 -12; methyl propanoate (1.68 ± 0.36) × 10 -11; methyl butanoate (4.77 ± 0.87) × 10 -11; methyl pentanoate (7.84 ± 1.15) × 10 -11; methyl hexanoate (1.09 ± 0.31) × 10 -10; methyl heptanoate (1.56 ± 0.37) × 10 -10; methyl cyclohexane carboxylate (3.32 ± 0.76) × 10 -10; methyl-2-methyl butanoate (9.41 ± 1.39) × 10 -11. In addition rate coefficients (in units of 10 -11 cm 3 molecule -1 s -1) have been obtained for the reactions of OH radicals with the following compounds: methyl butanoate (3.55 ± 0.71), methyl pentanoate (5.41 ± 1.08), and methyl-2-methyl butanoate (4.08 ± 0.82). Using the kinetic rate data tropospheric lifetimes for the methyl alkyl esters with respect to their reactions with OH, and Cl have been estimated for typical ambient air concentrations of these oxidants.

  6. Metabolism of (2-14C)acetate and its use in assessing hepatic Krebs cycle activity and gluconeogenesis

    SciTech Connect

    Schumann, W.C.; Magnusson, I.; Chandramouli, V.; Kumaran, K.; Wahren, J.; Landau, B.R. )

    1991-04-15

    To examine the fate of the carbons of acetate and to evaluate the usefulness of labeled acetate in assessing intrahepatic metabolic processes during gluconeogenesis, (2-14C)acetate, (2-14C)ethanol, and (1-14C)ethanol were infused into normal subjects fasted 60 h and given phenyl acetate. Distributions of 14C in the carbons of blood glucose and glutamate from urinary phenylacetylglutamine were determined. With (2-14C)acetate and (2-14C)ethanol, carbon 1 of glucose had about twice as much 14C as carbon 3. Carbon 2 of glutamate had about twice as much 14C as carbon 1 and one-half to one-third as much as carbon 4. There was only a small amount in carbon 5. These distributions are incompatible with the metabolism of (2-14C)acetate being primarily in liver. Therefore, (2-14C)acetate cannot be used to study Krebs cycle metabolism in liver and in relationship to gluconeogenesis, as has been done. The distributions can be explained by: (a) fixation of 14CO2 from (2-14C)acetate in the formation of the 14C-labeled glucose and glutamate in liver and (b) the formation of 14C-labeled glutamate in a second site, proposed to be muscle. (1,3-14C)Acetone formation from the (2-14C)acetate does not contribute to the distributions, as evidenced by the absence of 14C in carbons 2-4 of glutamate after (1-14C)ethanol administration.

  7. The Antibacterial Activity of Acetic Acid against Biofilm-Producing Pathogens of Relevance to Burns Patients

    PubMed Central

    Halstead, Fenella D.; Rauf, Maryam; Moiemen, Naiem S.; Bamford, Amy; Wearn, Christopher M.; Fraise, Adam P.; Lund, Peter A.; Oppenheim, Beryl A.; Webber, Mark A.

    2015-01-01

    Introduction Localised infections, and burn wound sepsis are key concerns in the treatment of burns patients, and prevention of colonisation largely relies on biocides. Acetic acid has been shown to have good antibacterial activity against various planktonic organisms, however data is limited on efficacy, and few studies have been performed on biofilms. Objectives We sought to investigate the antibacterial activity of acetic acid against important burn wound colonising organisms growing planktonically and as biofilms. Methods Laboratory experiments were performed to test the ability of acetic acid to inhibit growth of pathogens, inhibit the formation of biofilms, and eradicate pre-formed biofilms. Results Twenty-nine isolates of common wound-infecting pathogens were tested. Acetic acid was antibacterial against planktonic growth, with an minimum inhibitory concentration of 0.16–0.31% for all isolates, and was also able to prevent formation of biofilms (at 0.31%). Eradication of mature biofilms was observed for all isolates after three hours of exposure. Conclusions This study provides evidence that acetic acid can inhibit growth of key burn wound pathogens when used at very dilute concentrations. Owing to current concerns of the reducing efficacy of systemic antibiotics, this novel biocide application offers great promise as a cheap and effective measure to treat infections in burns patients. PMID:26352256

  8. Activity of C-7 substituted cyclic acetal derivatives of mitomycin C and porfiromycin against hypoxic and oxygenated EMT6 carcinoma cells in vitro and in vivo.

    PubMed

    Rockwell, S; Keyes, S R; Loomis, R; Kelley, M; Vyas, D M; Wong, H; Doyle, T W; Sartorelli, A C

    1991-06-01

    A series of cyclic acetal derivatives of mitomycin C (MC) and porfiromycin (POR) were tested for their ability to kill hypoxic and oxygenated EMT6 tumor cells. Amino methyl acetal and thioacetal substitutions at C-7 of MC and POR dramatically increased the cytotoxicity of the compounds to hypoxic EMT6 tumor cells in vitro but had little effect on the aerobic toxicities. In contrast, a methyl substitution at N1a markedly decreased the aerobic cytotoxicities of the compounds but did not alter the hypoxic cytotoxicities. The POR acetal, BMY-42355, had the largest differential between hypoxic and aerobic cytotoxicities yet observed among MC analogs. Preliminary studies in mice showed that BMY-42355 had good antineoplastic activity when used alone or in combination with radiation and was less toxic than POR; the therapeutic ratio of this compound in these initial studies was higher than those of either MC or POR. PMID:2049227

  9. Lead exposure in pheochromocytoma cells induces persistent changes in amyloid precursor protein gene methylation patterns.

    PubMed

    Li, Yuan-Yuan; Chen, Tian; Wan, Yanjian; Xu, Shun-qing

    2012-08-01

    It has been suggested that lead (Pb) exposure in early life may increase amyloid precursor protein (APP) expression and promote the pathogenesis of Alzheimer's disease in old age. The current study examined whether the DNA methylation patterns of APP gene in rat pheochromocytoma (PC12) cells changed after Pb acetate exposure. Undifferentiated PC12 cells were exposed to three doses of Pb acetate (50, 250, and 500 nM) and one control for 2 days or 1 week. The methylation patterns of APP promoter and global DNA methylation were analyzed. The DNA methyltransferase 1 (DNMT1) expression and the level of amyloid β peptide (Aβ) were also investigated. The results showed that the exposure of the three concentrations of Pb acetate could make the APP promoter hypomethylated. The global DNA methylation level and the expression of DNMT1 were changed in the 500 nM group after 2 days exposure and in the 250 and 500 nM group after 7 days exposure. Thus, Pb may exert neurotoxic effects through mechanisms that alter the global and promoter methylation patterns of APP gene. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012. PMID:22764079

  10. Microbial process for the preparation of acetic acid as well as solvent for its extraction from the fermentation broth

    DOEpatents

    Gaddy, James L.; Clausen, Edgar C.; Ko, Ching-Whan; Wade, Leslie E.; Wikstrom, Carl V.

    2002-01-01

    A modified water-immiscible solvent useful in the extraction of acetic acid from aqueous streams is a substantially pure mixture of isomers of highly branched di-alkyl amines. This solvent is substantially devoid of mono-alkyl amines and alcohols. Solvent mixtures formed of such a modified solvent with a desired cosolvent, preferably a low boiling hydrocarbon which forms an azeotrope with water are useful in the extraction of acetic acid from aqueous gaseous streams. An anaerobic microbial fermentation process for the production of acetic acid employs such solvents, under conditions which limit amide formation by the solvent and thus increase the efficiency of acetic acid recovery. Methods for the direct extraction of acetic acid and the extractive fermentation of acetic acid also employ the modified solvents and increase efficiency of acetic acid production. Such increases in efficiency are also obtained where the energy source for the microbial fermentation contains carbon dioxide and the method includes a carbon dioxide stripping step prior to extraction of acetic acid in solvent.

  11. Microbial process for the preparation of acetic acid as well as solvent for its extraction from the fermentation broth

    DOEpatents

    Gaddy, James L.; Clausen, Edgar C.; Ko, Ching-Whan; Wade, Leslie E.; Wikstrom, Carl V.

    2006-07-11

    A modified water-immiscible solvent useful in the extraction of acetic acid from aqueous streams is a substantially pure mixture of isomers of highly branched di-alkyl amines. This solvent is substantially devoid of mono-alkyl amines and alcohols. Solvent mixtures formed of such a modified solvent with a desired cosolvent, preferably a low boiling hydrocarbon which forms an azeotrope with water are useful in the extraction of acetic acid from aqueous gaseous streams. An anaerobic microbial fermentation process for the production of acetic acid employs such solvents, under conditions which limit amide formation by the solvent and thus increase the efficiency of acetic acid recovery. Methods for the direct extraction of acetic acid and the extractive fermentation of acetic acid also employ the modified solvents and increase efficiency of acetic acid production. Such increases in efficiency are also obtained where the energy source for the microbial fermentation contains carbon dioxide and the method includes a carbon dioxide stripping step prior to extraction of acetic acid in solvent.

  12. Strain IMB-1, a novel bacterium for the removal of methyl bromide in fumigated agricultural soils

    USGS Publications Warehouse

    Connell, Hancock T.L.; Costello, A.M.; Lidstrom, M.E.; Oremland, R.S.

    1998-01-01

    A facultatively methylotrophic bacterium, strain IMB-1, that has been isolated from agricultural soil grows on methyl bromide (MeBr), methyl iodide, methyl chloride, and methylated amines, as well as on glucose, pyruvate, or acetate. Phylogenetic analysis of its 16S rRNA gene sequence indicates that strain IMB-1 classes in the alpha subgroup of the class Proteobacteria and is closely related to members of the genus Rhizobium. The ability of strain IMB-1 to oxidize MeBr to CO2 is constitutive in cells regardless of the growth substrate. Addition of cell suspensions of strain IMB-1 to soils greatly accelerates the oxidation of MeBr, as does pretreatment of soils with low concentrations of methyl iodide. These results suggest that soil treatment strategies can be devised whereby bacteria can effectively consume MeBr during field fumigations, which would diminish or eliminate the outward flux of MeBr to the atmosphere.

  13. Megestrol acetate for treatment of endometriosis.

    PubMed

    Schlaff, W D; Dugoff, L; Damewood, M D; Rock, J A

    1990-04-01

    Between 1977-1989, 29 women with symptomatic endometriosis were treated with megestrol acetate by the Johns Hopkins Division of Reproductive Endocrinology. All had previously received one or more alternative medical treatments for endometriosis, in each case discontinued because of poor response or development of unacceptable side effects. Treatment consisted of a daily dose of 40 mg megestrol acetate orally for up to 24 months. Disease-related symptoms (dysmenorrhea, noncyclic pelvic pain, and dyspareunia) were relieved in 86% of the subjects treated with an adequate course of therapy. Side effects were fairly well tolerated, although eight women discontinued treatment within 2 months and two others stopped the drug by 4 months. These preliminary findings suggest that megestrol acetate may be an effective treatment for patients with endometriosis, even those who have been unresponsive to other modes of therapy. PMID:2314784

  14. Genetic Control of Methyl Halide Production in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Rhew, R. C.; Ostergaard, L.; Saltzman, E. S.; Yanofsky, M. F.

    2003-12-01

    Methyl chloride and methyl bromide are the primary carriers of natural chlorine and bromine to the stratosphere where they catalyze the destruction of ozone, whereas methyl iodide influences aerosol formation and ozone loss in the troposphere. Methyl bromide is also an agricultural fumigant whose use is scheduled to be phased out by international agreement. Despite the economic and environmental importance of these methyl halides, their natural sources and biological production mechanisms are poorly understood. Currently identified sources include oceans, biomass burning, industrial and agricultural use, fuel combustion, salt marshes, wetlands, rice paddies, certain terrestrial plants and fungi, and abiotic processes. We demonstrate that the model plant Arabidopsis thaliana produces and emits methyl halides and that the enzyme primarily responsible for the production is encoded by the HARMLESS TO OZONE LAYER (HOL) gene located on chromosome II. In mutant plants that have a disruption of the HOL gene, methyl halide production is largely eliminated. A phylogenetic analysis using the HOL gene suggests that the ability to produce methyl halides is widespread among vascular plants. This approach provides a genetic basis for understanding and predicting patterns of methyl halide production by plants.

  15. DNA methylation impacts on learning and memory in aging

    PubMed Central

    Liu, Liang; van Groen, Thomas; Kadish, Inga; Tollefsbol, Trygve O.

    2008-01-01

    Learning and memory are two of the fundamental cognitive functions that confer us the ability to accumulate knowledge from our experiences. Although we use these two mental skills continuously, understanding the molecular basis of learning and memory is very challenging. Methylation modification of DNA is an epigenetic mechanism that plays important roles in regulating gene expression, which is one of the key processes underlying the functions of cells including neurons. Interestingly, a genome-wide decline in DNA methylation occurs in the brain during normal aging, which coincides with a functional decline in learning and memory with age. It has been speculated that DNA methylation in neurons might be involved in memory coding. However, direct evidence supporting the role of DNA methylation in memory formation is still under investigation. This particular function of DNA methylation has not drawn wide attention despite several important studies that have provided supportive evidence for the epigenetic control of memory formation. To facilitate further exploration of the epigenetic basis of memory function, we will review existing studies on DNA methylation that are related to the development and function of the nervous system. We will focus on studies illustrating how DNA methylation regulates neural activities and memory formation via the control of gene expression in neurons, and relate these studies to various age-related neurological disorders that affect cognitive functions. PMID:17850924

  16. First chemoenzymatic synthesis of (+)-2-carboxypyrrolidine-3-acetic acid, the nucleus of kainoid amino acids.

    PubMed

    Felluga, Fulvia; Forzato, Cristina; Nitti, Patrizia; Pitacco, Giuliana; Ghelfi, Franco; Valentin, Ennio

    2012-02-01

    The distinctive nucleus of kainoid amino acids, (2S,3R)-(+)-2-carboxypyrrolidine-3-acetic acid 6, was synthesized by a chemoenzymatic process, exploiting the diastereomeric cis/trans methyl pyroglutamate derivatives 10a-c/11a-c as key intermediates. These mixtures, when subjected to a kinetic resolution mediated by α-chymotrypsin, reacted diastereo-, regio-, and enantioselectively to give the trans derivatives (+)-10a-c possessing the correct (2S,3R) configuration. Subsequently, the desired product (2S,3R)-(+)-6 could be obtained after well-established transformations. PMID:22180179

  17. Mercury methylation in mine wastes collected from abandoned mercury mines in the USA

    USGS Publications Warehouse

    Gray, J.E.; Hines, M.E.; Biester, H.; Lasorsa, B.K.

    2003-01-01

    Speciation and transformation of Hg was studied in mine wastes collected from abandoned Hg mines at McDermitt, Nevada, and Terlingua, Texas, to evaluate formation of methyl-Hg, which is highly toxic. In these mine wastes, we measured total Hg and methyl-Hg contents, identified various Hg compounds using a pyrolysis technique, and determined rates of Hg methylation and methyl-Hg demethylation using isotopic-tracer methods. Mine wastes contain total Hg contents as high as 14000 ??g/g and methyl-Hg concentrations as high as 88 ng/g. Mine wastes were found to contain variable amounts of cinnabar, metacinnabar, Hg salts, Hg0, and Hg0 and Hg2+ sorbed onto matrix particulates. Samples with Hg0 and matrix-sorbed Hg generally contained significant methyl-Hg contents. Similarly, samples containing Hg0 compounds generally produced significant Hg methylation rates, as much as 26%/day. Samples containing mostly cinnabar showed little or no Hg methylation. Mine wastes with high methyl-Hg contents generally showed low methyl-Hg demethylation, suggesting that Hg methylation was dominant. Methyl-Hg demethylation was by both oxidative and microbial pathways. The correspondence of mine wastes containing Hg0 compounds and measured Hg methylation suggests that Hg0 oxidizes to Hg2+, which is subsequently bioavailable for microbial Hg methylation.

  18. Would acetate (or its derivatives) be the most reliable guide to life on terraqueous globes?

    NASA Astrophysics Data System (ADS)

    Russell, Michael; Martin-Torres, Javier; Yung, Yuk; Kanik, Isik

    2010-05-01

    At bottom life hydrogenates carbon dioxide. But so does serpentinization-to methane-hence the problem of diagnosing its source (Mumma et al. 2009). However, this abiotic process does not appear to produce acetate or acetic acid (CH3COOH) in measurable quantities-only the acetogenic and sulfate-reducing bacteria do that. On the early Earth it seems that the homoacetogens were the first to resolve the tension between CO2 and H2 via the autotrophic acetyl coenzyme-A pathway. The acetyl co-A pathway employs two separate redox controlled tributaries-one Ni-Fe-directed, merely reduces CO2 to CO, while the other, initially molybdenum-directed, reduces CO2 through to a methyl group. The CO and the -CH3 are then assembled on the nickel-bearing acetyl coenzyme-A synthase. Such a complex dual delivery system from contrasting redox conditions could not be prefigured by serpentinization but required a chemiosmotic drive, as did the origin of life itself (Nitschke and Russell 2009). Homoacetogens can compete successfully against the methanoarchaea for H2 and CO2 in the cold, as can the sulfate-reducing acetate-generating bacteria (Krumholz et al. 1999). Thus we argue that acetate or acetic acid effluent (depending on pH) from putative microbes on wet rocky planets would be a more reliable indicator of life. What are the difficulties? The most critical is that in ground-waters and oceans with pH >5 acetate remains in solution and would therefore not be detectable remotely. Even were the waters acidic enough to release volatile acetic acid, it would be prone to photo- and chemical oxidation. However, apart from CO2 and CH4, the products are formic (HCOOH), glycolic (HOCH2.COOH) and tartaric (HOOC.HCOH.HOCH.COOH) acids (Ogata et al. 1981). Remote sensing in the ultraviolet to near-infrared might be used for detection of all these acids, especially when their concentrations are enhanced in plumes. In situ techniques would be required for acetate detection. Krumholz, L.R. et al

  19. The effects of acetaldehyde, glyoxal and acetic acid on the heterogeneous reaction of nitrogen dioxide on gamma-alumina.

    PubMed

    Sun, Zhenyu; Kong, Lingdong; Ding, Xiaoxiao; Du, Chengtian; Zhao, Xi; Chen, Jianmin; Fu, Hongbo; Yang, Xin; Cheng, Tiantao

    2016-04-14

    Heterogeneous reactions of nitrogen oxides on the surface of aluminium oxide result in the formation of adsorbed nitrite and nitrate. However, little is known about the effects of other species on these heterogeneous reactions and their products. In this study, diffuse reflectance infrared spectroscopy (DRIFTS) was used to analyze the process of the heterogeneous reaction of NO2 on the surface of aluminium oxide particles in the presence of pre-adsorbed organic species (acetaldehyde, glyoxal and acetic acid) at 298 K and reveal the influence of these organic species on the formation of adsorbed nitrite and nitrate. It was found that the pre-adsorption of organic species (acetaldehyde, glyoxal and acetic acid) on γ-Al2O3 could suppress the formation of nitrate to different extents. Under the same experimental conditions, the suppression of the formation of nitrate by the pre-adsorption of acetic acid is much stronger than that by pre-adsorption of acetaldehyde and glyoxal, indicating that the influence of acetic acid on the heterogeneous reaction of NO2 is different from that of acetaldehyde and glyoxal. Surface nitrite is formed and identified to be an intermediate product. For the heterogeneous reaction of NO2 on the surface of γ-Al2O3 with and without the pre-adsorption of acetaldehyde and glyoxal, it is firstly formed and then gradually disappears as the reaction proceeds, but for the reaction with the pre-adsorption of acetic acid, it is the final main product besides nitrate. This indicates that the pre-adsorption of acetic acid would promote the formation of nitrite, while the others would not change the trend of the formation of nitrite. The possible influence mechanisms of the pre-adsorption of acetaldehyde, glyoxal and acetic acid on the heterogeneous conversion of NO2 on γ-Al2O3 are proposed and atmospheric implications based on these results are discussed. PMID:26745767

  20. DNA Methylation is Developmentally Regulated for Genes Essential for Cardiogenesis

    PubMed Central

    Chamberlain, Alyssa A.; Lin, Mingyan; Lister, Rolanda L.; Maslov, Alex A.; Wang, Yidong; Suzuki, Masako; Wu, Bingruo; Greally, John M.; Zheng, Deyou; Zhou, Bin

    2014-01-01

    Background DNA methylation is a major epigenetic mechanism altering gene expression in development and disease. However, its role in the regulation of gene expression during heart development is incompletely understood. The aim of this study is to reveal DNA methylation in mouse embryonic hearts and its role in regulating gene expression during heart development. Methods and Results We performed the genome‐wide DNA methylation profiling of mouse embryonic hearts using methyl‐sensitive, tiny fragment enrichment/massively parallel sequencing to determine methylation levels at ACGT sites. The results showed that while global methylation of 1.64 million ACGT sites in developing hearts remains stable between embryonic day (E) 11.5 and E14.5, a small fraction (2901) of them exhibit differential methylation. Gene Ontology analysis revealed that these sites are enriched at genes involved in heart development. Quantitative real‐time PCR analysis of 350 genes with differential DNA methylation showed that the expression of 181 genes is developmentally regulated, and 79 genes have correlative changes between methylation and expression, including hyaluronan synthase 2 (Has2). Required for heart valve formation, Has2 expression in the developing heart valves is downregulated at E14.5, accompanied with increased DNA methylation in its enhancer. Genetic knockout further showed that the downregulation of Has2 expression is dependent on DNA methyltransferase 3b, which is co‐expressed with Has2 in the forming heart valve region, indicating that the DNA methylation change may contribute to the Has2 enhancer's regulating function. Conclusions DNA methylation is developmentally regulated for genes essential to heart development, and abnormal DNA methylation may contribute to congenital heart disease. PMID:24947998

  1. Synthesis of diversely substituted 2-(furan-3-yl)acetates from allenols through cascade carbonylations.

    PubMed

    He, Yan; Zhang, Xinying; Fan, Xuesen

    2015-11-21

    Novel synthesis of diversely substituted 2-(furan-3-yl)acetates via palladium-catalyzed one-pot multi-component reactions of allenols, aryl iodides, alcohols, and carbon monoxide has been developed. Notably, the formation of the title compounds features a cascade process combining carbonylation of aryl iodide, alcohoxyl carbonylation of the in situ formed allyl palladium complex, and intramolecular condensation of the α-hydroxyl enone intermediate. Moreover, the 2-(furan-3-yl)acetates obtained herein were found to be ready intermediates for the construction of the biologically significant naphtho[1,2-b]furan-5-ol scaffold. PMID:26399394

  2. DNA methylation in fibrosis.

    PubMed

    Dowson, Christopher; O'Reilly, Steven

    2016-09-01

    Fibrosis is characterised by an exuberant wound healing response and the major cell type responsible is the myofibroblast. The myofibroblast is typified by excessive ECM production and contractile activity and is demarcated by alpha-smooth muscle actin expression. What has recently come to light is that the activation of the fibroblast to myofibroblast may be under epigenetic control, specifically methylation. Methylation of DNA is a conserved mechanism to precisely regulate gene expression in a specific context. Hypermethylation leads to gene repression and hypomethylation results in gene induction. Methylation abnormalities have recently been uncovered in fibrosis, both organ specific and widespread fibrosis. The fact that these methylation changes are rapid and reversible lends themselves amenable to therapeutic intervention. This review considers the role of methylation in fibrosis and the activation of the myofibroblasts and how this could be targeted for fibrosis. Fibrosis is of course currently intractable to therapeutics and is a leading cause of morbidity and mortality and is an urgent unmet clinical need. PMID:27346523

  3. O-Methyl sugars in lipopolysaccharides of Rhodospirillacea. Identification of 3-O-methyl-d-mannose in Rhodopseudomonas viridis and of 4-O-methyl-d-xylose and 3-O-methyl-6-deoxy-d-talose in Rhodopseudomonas palustris respectively

    PubMed Central

    Weckesser, Jürgen; Mayer, Hubert; Fromme, Inge

    1973-01-01

    1. This paper deals with the identification of three O-methyl sugars in lipopolysaccharides isolated from strains of the Gram-negative photosynthetic family Rhodospirillaceae. In addition to the previously described 3-O-methyl-l-xylose, a second O-methyl sugar was encountered in the lipopolysaccharide of Rhodopseudomonas viridis F, namely 3-O-methyl-d-mannose. The lipopolysaccharides of two strains of Rhodopseudomonas palustris (strain 1e5 and 8/1) contain two O-methylsugars, 4-O-methyl-d-xylose and 3-O-methyl-6-deoxy-d-talose (d-acovenose). 4-O-Methyl-d-xylose, but not 3-O-methyl-6-deoxy-d-talose, could be identified in the lipopolysaccharides of the strains K/1 and 2/2 of the same species. 2. The O-methyl sugars described in this communication were isolated by paper chromatography and identified by g.l.c., paper chromatography, high-voltage electrophoresis and mass spectrometry. Besides the genuine sugars, their alditol acetates and their demethylated (parental) forms were investigated. Optical rotation measurements and, in one case, enzymic reactions were used to establish the optical configuration of the sugars under investigation. PMID:4764262

  4. A new source of methyl glyoxal in the aqueous phase

    NASA Astrophysics Data System (ADS)

    Rodigast, M.; Mutzel, A.; Schindelka, J.; Herrmann, H.

    2015-11-01

    Carbonyl compounds are ubiquitous in atmospheric multiphase system participating in gas, particle, and aqueous-phase chemistry. One important compound is methyl ethyl ketone (MEK), as it is detected in significant amounts in the gas phase as well as in cloud water, ice, and rain. Consequently, it can be expected that MEK influences the liquid phase chemistry. Therefore, the oxidation of MEK and the formation of corresponding oxidation products were investigated in the aqueous phase. Several oxidation products were identified from the oxidation with OH radicals, including 2,3-butanedione, hydroxyacetone, and methyl glyoxal. The molar yields were 29.5 % for 2,3-butanedione, 3.0 % for hydroxyacetone, and 9.5 % for methyl glyoxal. Since methyl glyoxal is often related to the formation of organics in the aqueous phase, MEK should be considered for the formation of aqueous secondary organic aerosol (aqSOA). Based on the experimentally obtained data, a reaction mechanism for the formation of methyl glyoxal has been developed and evaluated with a model study. Besides known rate constants, the model contains measured photolysis rate constants for MEK (kp = 5 × 10-5 s-1), 2,3-butanedione (kp = 9 × 10-6 s-1), methyl glyoxal (kp = 3 × 10-5 s-1), and hydroxyacetone (kp = 2 × 10-5 s-1). From the model predictions, a branching ratio of 60/40 for primary/secondary H-atom abstraction at the MEK skeleton was found. This branching ratio reproduces the experiment results very well, especially the methyl glyoxal formation, which showed excellent agreement. Overall, this study demonstrates MEK as a methyl glyoxal precursor compound for the first time.

  5. An experimental determination of ferrous chloride and acetate complexation in aqueous solutions to 300°C

    NASA Astrophysics Data System (ADS)

    Palmer, Donald A.; Hyde, K. E.

    1993-04-01

    The formation of the monochloroiron(II) complex, FeCl +, was studied potentiometrically from 125 to 295°C at 25 degree intervals at one molal ionic strength in aqueous solutions containing acetic acid, sodium acetate, and sodium trifluoromethanesulfonate. In this method, competition between chloride and acetate ions for the ferrous cation resulted in a change in solution pH, which in turn was monitored in situ in a hydrogen-electrode, concentration cell. A simple empirical approach was used to extrapolate these formation quotients to infinite dilution. The resulting constants proved to be in excellent agreement with previous spectrophotometric results obtained from 25 to 200°C. Thus, the present study confirms the validity of the conclusions made based on these earlier data concerning the solubility of Fe-containing minerals in hydrothermal brines. Formation constants at infinite dilution for FeCl + are compared with the stability of ferrous acetate and hydroxide complexes. The original potentiometric titration data for ferrous acetate complex formation were combined in a new fit with values determined from the present study at unit ionic strength. Two empirical treatments (namely the isocoulombic method and the temperature/water density function) were considered for fitting and extrapolating the infinite dilution formation constants to 350°C.

  6. Synthesis of Cellulose Acetate from Cotton Byproducts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton burr and cottonseed hull are relatively inexpensive cotton byproducts. In an effort to derive greater value out of these natural renewable materials, we have succeeded in converting part of them into cellulose acetate without prior chemical breakdown or physical separation of cellulose, ligni...

  7. Advanced Colloids Experiment (ACE-T1)

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Sicker, Ron; Brown, Dan; Eustace, John

    2015-01-01

    Increment 45 - 46 Science Symposium presentation of Advanced Colloids Experiment (ACE-T1) to RPO. The purpose of this event is for Principal Investigators to present their science objectives, testing approach, and measurement methods to agency scientists, managers, and other investigators.

  8. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium acetate. 184.1185 Section 184.1185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  9. 21 CFR 556.380 - Melengestrol acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Melengestrol acetate. 556.380 Section 556.380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS TOLERANCES FOR RESIDUES OF NEW ANIMAL DRUGS IN FOOD Specific Tolerances for Residues of New Animal Drugs §...

  10. Heat Bonding of Irradiated Ethylene Vinyl Acetate

    NASA Technical Reports Server (NTRS)

    Slack, D. H.

    1986-01-01

    Reliable method now available for joining parts of this difficult-tobond material. Heating fixture encircles ethylene vinyl acetate multiplesocket part, providing heat to it and to tubes inserted in it. Fixtures specially designed to match parts to be bonded. Tube-and-socket bonds made with this technique subjected to tensile tests. Bond strengths of 50 percent that of base material obtained consistently.

  11. 21 CFR 522.1881 - Prednisolone acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Prednisolone acetate. 522.1881 Section 522.1881 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... used as supportive therapy pre- and postoperatively and for various stress conditions...

  12. Reactions of germanium tetrahalides with ketene acetals

    SciTech Connect

    Efimova, I.V.; Kazankova, M.A.; Lutsenko, I.F.

    1985-05-01

    Recently, the authors reported that alkyl vinyl ethers and terminal alkynes are readily germylated by germanium tetrahalides in the presence of a tertiary amine. To extend the range of applicability of this reaction and to obtain additional information on its mechanism, the authors study reactions of ketene acetals with germanium tetrachloride and tetrabromide in the presence of triethylamine.

  13. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS §...

  14. Process for the preparation of vinyl acetate

    DOEpatents

    Tustin, G.C.; Zoeller, J.R.; Depew, L.S.

    1998-02-17

    This invention pertains to the preparation of vinyl acetate by contacting within a contact zone a mixture of ketene and acetaldehyde with an acid catalyst at about one bar pressure and between about 85 and 200 C and removing the reaction products from the contact zone.

  15. Process for the preparation of vinyl acetate

    DOEpatents

    Tustin, Gerald Charles; Zoeller, Joseph Robert; Depew, Leslie Sharon

    1998-01-01

    This invention pertains to the preparation of vinyl acetate by contacting within a contact zone a mixture of ketene and acetaldehyde with an acid catalyst at about one bar pressure and between about 85.degree. and 200.degree. C. and removing the reaction products from the contact zone.

  16. Studies of LDL oxidation following alpha-, gamma-, or delta-tocotrienyl acetate supplementation of hypercholesterolemic humans.

    PubMed

    O'Byrne, D; Grundy, S; Packer, L; Devaraj, S; Baldenius, K; Hoppe, P P; Kraemer, K; Jialal, I; Traber, M G

    2000-11-01

    In vitro tocotrienols (T3s) have potent vitamin E antioxidant activity, but unlike tocopherols can inhibit cholesterol synthesis by suppressing 3-hydroxy-3-methyl-glutarylCoA (HMG-CoA) reductase. Because hypercholesterolemia is a major risk factor for coronary artery disease and oxidative modification of low-density lipoprotein (LDL) may be involved in atherogenesis, we investigated whether daily supplements of placebo, or alpha-, gamma-, or delta- (alpha-, gamma-, or delta-) tocotrienyl acetates would alter serum cholesterol or LDL oxidative resistance in hypercholesterolemics in a double-blind placebo controlled study. Subjects were randomly assigned to receive placebo (n = 13), alpha- (n = 13), gamma- (n = 12), or delta- (n = 13) tocotrienyl acetate supplements (250 mg/d). All subjects followed a low-fat diet for 4 weeks, then took supplements with dinner for the following 8 weeks while still continuing diet restrictions. Plasma alpha- and gamma-tocopherols were unchanged by supplementation. Plasma T3s were undetectable initially and always in the placebo group. Following supplementation in the respective groups plasma concentrations were: alpha-T3 0.98 +/- 0.80 micromol/l, gamma-T3 0.54 +/- 0.45 micromol/l, and delta-T3 0.09 +/- 0.07 micromol/l. Alpha-T3 increased in vitro LDL oxidative resistance (+22%, p <.001) and decreased its rate of oxidation (p <. 01). Neither serum or LDL cholesterol nor apolipoprotein B were significantly decreased by tocotrienyl acetate supplements. This study demonstrates that: (i) tocotrienyl acetate supplements are hydrolyzed, absorbed, and detectable in human plasma; (ii) tocotrienyl acetate supplements do not lower cholesterol in hypercholesterolemic subjects on low-fat diets; and (iii) alpha-T3 may be potent in decreasing LDL oxidizability. PMID:11063909

  17. [DNA methylation in obesity].

    PubMed

    Pokrywka, Małgorzata; Kieć-Wilk, Beata; Polus, Anna; Wybrańska, Iwona

    2014-01-01

    The number of overweight and obese people is increasing at an alarming rate, especially in the developed and developing countries. Obesity is a major risk factor for diabetes, cardiovascular disease, and cancer, and in consequence for premature death. The development of obesity results from the interplay of both genetic and environmental factors, which include sedentary life style and abnormal eating habits. In the past few years a number of events accompanying obesity, affecting expression of genes which are not directly connected with the DNA base sequence (e.g. epigenetic changes), have been described. Epigenetic processes include DNA methylation, histone modifications such as acetylation, methylation, phosphorylation, ubiquitination, and sumoylation, as well as non-coding micro-RNA (miRNA) synthesis. In this review, the known changes in the profile of DNA methylation as a factor affecting obesity and its complications are described. PMID:25531701

  18. Molecular Biology and Genetics of the Acetate-Utilizing Methanogenic Bacteria

    SciTech Connect

    Robert P. Gunsalus

    2003-07-21

    Methane biosynthesis by the Methanosarcina species, in contrast to other methanogens, occurs from the full range of methanogenic substrates that include acetate, methanol, tri-methyl, di-methyl, and methyl-amine, methyl-sulfides, and in limited instances, H2/CO2. The Methanosarcina are also versatile in their ability to adapt and grow in habitats of varying osmolarity ranging from fresh water environments, marine environments, and to hyper saline environments (ca to 1.2 M NaCl). To facilitate studies that address the biochemistry, molecular biology and physiology of these organisms, we have constructed a whole-genome microarray to identify classes of differentially expressed genes in M. mazei strain Goe1. We propose to further identify and examine how genes and their proteins involved in the synthesis and transport of osmolytes in the cell are regulated. These compounds include N-epsilon-acetyl-beta-lysine, alpha-glutamate, betaine, and potassium whose levels within the cell are modulated in order to provide appropriate osmotic balance. We will identify differentially expressed genes involved in hydrogen and carbon dioxide sequestration since M. mazei strain Goe1 is currently the only practical model for such study. Finally, we will explore the essential roles of two metals, molybdate and tungstate, in methanogen regulation and metabolism of these environmentally essential organsims. The above studies will advance our general understanding of how methanogens respond to their environmental signals, and adapt by adjusting their physiology to thrive in changing anaerobic habitats whether natural or man-made.

  19. Thiosulphate conversion in a methane and acetate fed membrane bioreactor.

    PubMed

    Suarez-Zuluaga, Diego A; Timmers, Peer H A; Plugge, Caroline M; Stams, Alfons J M; Buisman, Cees J N; Weijma, Jan

    2016-02-01

    The use of methane and acetate as electron donors for biological reduction of thiosulphate in a 5-L laboratory membrane bioreactor was studied and compared to disproportionation of thiosulphate as competing biological reaction. The reactor was operated for 454 days in semi-batch mode; 30 % of its liquid phase was removed and periodically replenished (days 77, 119, 166, 258, 312 and 385). Although the reactor was operated under conditions favourable to promote thiosulphate reduction coupled to methane oxidation, thiosulphate disproportionation was the dominant microbial process. Pyrosequencing analysis showed that the most abundant microorganisms in the bioreactor were phototrophic green sulphur bacteria (GSB) belonging to the family Chlorobiaceae and thiosulphate-disproportionating bacteria belonging to the genus Desulfocapsa. Even though the reactor system was surrounded with opaque plastic capable of filtering most of the light, the GSB used it to oxidize the hydrogen sulphide produced from thiosulphate disproportionation to elemental sulphur. Interrupting methane and acetate supply did not have any effect on the microbial processes taking place. The ultimate goal of our research was to develop a process that could be applied for thiosulphate and sulphate removal and biogenic sulphide formation for metal precipitation. Even though the system achieved in this study did not accomplish the targeted conversion using methane as electron donor, it does perform microbial conversions which allow to directly obtain elemental sulphur from thiosulphate. PMID:26423279

  20. Aluminum(III) speciation with acetate and oxalate. A potentiometric and sup 27 Al NMR study

    SciTech Connect

    Thomas, F.; Rouiller, J.; Genevrier, F.; Boudot, D. ); Masion, A.; Bottero, J.Y. )

    1991-09-01

    Aluminum (III) hydrolysis and precipitation in the presence of acetic acid and oxalic acid have been studied by combining potentiometric titration and liquid-state {sup 27}Al NMR. The main aluminum species have thus been identified and quantified: unreacted hydrolyzed, complexed monomers, and the Al{sub 13} tridecamer. A solid species appeared when precipitation occurred and was quantified by difference with the other species. The quantitative evolution of these species was followed for pH values up to 5. Acetate forms weak complexes with aluminum. The precipitated phase was hypothesized to be aggregated Al{sub 13}. Oxalate forms strong multiligand complexes to form Al{sub 13} requires higher hydroxyl content. High oxalate contents (L/M > 1) inhibit tridecamer formation and precipitation occurs only at high pH values. With oxalate the precipitated phase seems to be devoid of Al{sub 13} and of a more condensed nature than it is with acetate.