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Sample records for enzymatic mnii oxidation

  1. Enzymatic microbial Mn(II) oxidation and Mn biooxide production in the Guaymas Basin deep-sea hydrothermal plume

    Science.gov (United States)

    Dick, Gregory J.; Clement, Brian G.; Webb, Samuel M.; Fodrie, F. Joel; Bargar, John R.; Tebo, Bradley M.

    2009-11-01

    Microorganisms play important roles in mediating biogeochemical reactions in deep-sea hydrothermal plumes, but little is known regarding the mechanisms that underpin these transformations. At Guaymas Basin (GB) in the Gulf of California, hydrothermal vents inject fluids laden with dissolved Mn(II) (dMn) into the deep waters of the basin where it is oxidized and precipitated as particulate Mn(III/IV) oxides, forming turbid hydrothermal "clouds". Previous studies have predicted extremely short residence times for dMn at GB and suggested they are the result of microbially-mediated Mn(II) oxidation and precipitation. Here we present biogeochemical results that support a central role for microorganisms in driving Mn(II) oxidation in the GB hydrothermal plume, with enzymes being the primary catalytic agent. dMn removal rates at GB are remarkably fast for a deep-sea hydrothermal plume (up to 2 nM/h). These rapid rates were only observed within the plume, not in background deep-sea water above the GB plume or at GB plume depths (˜1750-2000 m) in the neighboring Carmen Basin, where there is no known venting. dMn removal is dramatically inhibited under anoxic conditions and by the presence of the biological poison, sodium azide. A conspicuous temperature optimum of dMn removal rates (˜40 °C) and a saturation-like (i.e. Michaelis-Menten) response to O 2 concentration were observed, indicating an enzymatic mechanism. dMn removal was resistant to heat treatment used to select for spore-forming organisms, but very sensitive to low concentrations of added Cu, a cofactor required by the putative Mn(II)-oxidizing enzyme. Extended X-ray absorption fine structure spectroscopy (EXAFS) and synchrotron radiation-based X-ray diffraction (SR-XRD) revealed the Mn oxides to have a hexagonal birnessite or δ-MnO 2-like mineral structure, indicating that these freshly formed deep-sea Mn oxides are strikingly similar to primary biogenic Mn oxides produced by laboratory cultures of bacteria

  2. The effect of Ca2+ ions and ionic strength on Mn(II) oxidation by spores of the marine Bacillus sp. SG-1

    Science.gov (United States)

    Toyoda, Kazuhiro; Tebo, Bradley M.

    2013-01-01

    Manganese(IV) oxides, believed to form primarily through microbial activities, are extremely important mineral phases in marine environments where they scavenge a variety of trace elements and thereby control their distributions. The presence of various ions common in seawater are known to influence Mn oxide mineralogy yet little is known about the effect of these ions on the kinetics of bacterial Mn(II) oxidation and Mn oxide formation. We examined factors affecting bacterial Mn(II) oxidation by spores of the marine Bacillus sp. strain SG-1 in natural and artificial seawater of varying ionic conditions. Ca2+ concentration dramatically affected Mn(II) oxidation, while Mg2+, Sr2+, K+, Na+ and NO3- ions had no effect. The rate of Mn(II) oxidation at 10 mM Ca2+ (seawater composition) was four or five times that without Ca2+. The relationship between Ca2+ content and oxidation rate demonstrates that the equilibrium constant is small (on the order of 0.1) and the binding coefficient is 0.5. The pH optimum for Mn(II) oxidation changed depending on the amount of Ca2+ present, suggesting that Ca2+ exerts a direct effect on the enzyme perhaps as a stabilizing bridge between polypeptide components. We also examined the effect of varying concentrations of NaCl or KNO3 (0-2000 mM) on the kinetics of Mn(II) oxidation in solutions containing 10 mM Ca2+. Mn(II) oxidation was unaffected by changes in ionic strength (I) below 0.2, but it was inhibited by increasing salt concentrations above this value. Our results suggest that the critical coagulation concentration is around 200 mM of salt (I = ca. 0.2), and that the ionic strength of seawater (I > 0.2) accelerates the precipitation of Mn oxides around the spores. Under these conditions, the aggregation of Mn oxides reduces the supply of dissolved O2 and/or Mn2+ and inhibits the Mn(II) → Mn(III) step controlling the enzymatic oxidation of Mn(II). Our results suggest that the hardness and ionic strength of the aquatic environment

  3. Electronic spin resonance quantitative analysis of Mn(II) complexes anti oxidative activity using phosphate or organic buffer

    Energy Technology Data Exchange (ETDEWEB)

    Souchard, J.P.; Massol, M.; Nepveu, F. [Toulouse-3 Univ., 31 (France)

    1996-01-01

    Superoxide anion is implicated in the pathogenesis of several human diseases including ischaemia, atherosclerosis and inflammation when molecular or enzymatic antioxidant systems cannot regulate its formation. In order to investigate superoxide dismutase (SOD) mimics, a method using Electron Spin Resonance (ESR) has been developed to quantify anti-oxidative activities of Mn(II) compounds. The acetaldehyde / xanthine oxidase system produced superoxide anion and the 5,5-dimethyl-I-pyroline-N-oxide (DMPO) was used as spin trap. The complexing properties of the usual phosphate buffer towards Mn{sup 2+} being not negligible comparatively to those of the studied ligands, activities of free ligands and Mn(II) complexes have been compared according to the buffer, phosphate or organic. (Authors). 7 refs., 1 tab., 2 figs.,.

  4. Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1.

    Science.gov (United States)

    Bohu, Tsing; Santelli, Cara M; Akob, Denise M; Neu, Thomas R; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

    2015-01-01

    Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

  5. Characterization of pH dependent Mn(II oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    Directory of Open Access Journals (Sweden)

    Tsing eBohu

    2015-07-01

    Full Text Available Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB isolates limits our understanding of how pH influences biological Mn(II oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction (XRD, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase (MCO expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS, particularly superoxide, appeared to be more important for T-G1 mediated Mn(II oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

  6. Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    Science.gov (United States)

    Bohu, Tsing; Santelli, Cara M; Akob, Denise M.; Neu, Thomas R; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

    2015-01-01

    Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

  7. Acclimation of a marine microbial consortium for efficient Mn(II) oxidation and manganese containing particle production

    International Nuclear Information System (INIS)

    Zhou, Hao; Pan, Haixia; Xu, Jianqiang; Xu, Weiping; Liu, Lifen

    2016-01-01

    Highlights: • An efficient Mn(II) oxidation marine sediments microbial community was obtained. • High-throughput sequencing indicated new Mn(II) oxidation associated genus. • Na 3 MnPO 4 CO 3 and MnCO 3 were synthesized by the consortium. • Consortium exhibited Mn(II) oxidation performance over a range of harsh conditions. - Abstract: Sediment contamination with metals is a widespread concern in the marine environment. Manganese oxidizing bacteria (MOB) are extensively distributed in various environments, but a marine microbial community containing MOB is rarely reported. In this study, a consortium of marine metal-contaminated sediments was acclimated using Mn(II). The shift in community structure was determined through high-throughput sequencing. In addition, the consortium resisted several harsh conditions, such as toxic metals (1 mM Cu(II) and Fe(III)), and exhibited high Mn(II) oxidation capacities even the Mn(II) concentration was up to 5 mM. Meanwhile, biogenic Mn containing particles were characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and N 2 adsorption/desorption. Dye removal performance of the Mn containing particles was assayed using methylene blue, and 20.8 mg g −1 adsorption capacity was obtained. Overall, this study revealed several new genera associated with Mn(II) oxidation and rare biogenic Na 3 MnPO 4 CO 3. Results suggested the complexity of natural microbe-mediated Mn transformation.

  8. Mycogenic Mn(II) oxidation promotes remediation of acid mine drainage and other anthropogenically impacted environments

    Science.gov (United States)

    Santelli, C. M.; Chaput, D.; Hansel, C. M.; Burgos, W. D.

    2014-12-01

    Manganese is a pollutant in worldwide environments contaminated with metals and organics, such as acid mine drainage (AMD), freshwater ponds, and agricultural waste storage sites. Microorganisms contribute to the removal of dissolved Mn compounds in the environment by promoting Mn(II) oxidation reactions. The oxidation of Mn(II) results in the precipitation of sparingly soluble Mn(IV) oxide minerals, effectively removing the metal from the aqueous milieu (e.g., groundwater or wastewater streams). In recent years, our research has identified a diversity of Mn(II)-oxidizing fungi inhabiting these polluted environments, however their overall contribution to the remediation process in situ remains poorly understood. Here we present results of culture-based and Next Generation Sequencing (NGS) studies in AMD treatment systems actively remediating Mn and other metals where we profile the bacterial, fungal, algal and archaeal communities to determine the overall community diversity and to establish the relative abundance of known Mn(II) oxidizers. A variety of treatment systems with varying Mn-removal efficiencies were sampled to understand the relationship between remediation efficiency and microbial community composition and activity. Targeted-amplicon sequencing of DNA and RNA of the 16S rRNA genes (bacteria and archaea), 23S rRNA genes (algae) and ITS region (fungi) was performed using both 454 pyrosequencing and Illumina platforms. Results showed that only the fungal taxonomic profiles significantly differed between sites that removed the majority of influent Mn and those that did not. Specifically, Ascomycota (which include known Mn(II) oxidizers isolated from these treatment systems) dominated greater efficiency systems whereas less efficient systems were dominated by Basidiomycota. Furthermore, known Mn(II) oxidizers accounted for only a minor proportion of bacterial sequences but a far greater proportion of fungal sequences. These culture-independent studies lend

  9. Acclimation of a marine microbial consortium for efficient Mn(II) oxidation and manganese containing particle production

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Hao, E-mail: zhouhao@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Food and Environment, Dalian University of Technology, Panjin 124221 (China); Pan, Haixia [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Food and Environment, Dalian University of Technology, Panjin 124221 (China); Xu, Jianqiang [School of Life Science and Medicine, Dalian University of Technology, Panjin 124221 (China); Xu, Weiping; Liu, Lifen [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Food and Environment, Dalian University of Technology, Panjin 124221 (China)

    2016-03-05

    Highlights: • An efficient Mn(II) oxidation marine sediments microbial community was obtained. • High-throughput sequencing indicated new Mn(II) oxidation associated genus. • Na{sub 3}MnPO{sub 4}CO{sub 3} and MnCO{sub 3} were synthesized by the consortium. • Consortium exhibited Mn(II) oxidation performance over a range of harsh conditions. - Abstract: Sediment contamination with metals is a widespread concern in the marine environment. Manganese oxidizing bacteria (MOB) are extensively distributed in various environments, but a marine microbial community containing MOB is rarely reported. In this study, a consortium of marine metal-contaminated sediments was acclimated using Mn(II). The shift in community structure was determined through high-throughput sequencing. In addition, the consortium resisted several harsh conditions, such as toxic metals (1 mM Cu(II) and Fe(III)), and exhibited high Mn(II) oxidation capacities even the Mn(II) concentration was up to 5 mM. Meanwhile, biogenic Mn containing particles were characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and N{sub 2} adsorption/desorption. Dye removal performance of the Mn containing particles was assayed using methylene blue, and 20.8 mg g{sup −1} adsorption capacity was obtained. Overall, this study revealed several new genera associated with Mn(II) oxidation and rare biogenic Na{sub 3}MnPO{sub 4}CO{sub 3.} Results suggested the complexity of natural microbe-mediated Mn transformation.

  10. Efficient catalytic As(III) oxidation on the surface of ferrihydrite in the presence of aqueous Mn(II).

    Science.gov (United States)

    Lan, Shuai; Ying, Hong; Wang, Xiaoming; Liu, Fan; Tan, Wenfeng; Huang, Qiaoyun; Zhang, Jing; Feng, Xionghan

    2018-01-01

    Arsenic is a carcinogenic element that exists primarily as arsenate [As(V)] and arsenite [As(III)] in the nature environment, with As(III) being more toxic and mobile of the two species. In addition, ferrihydrite, which is widely distributed in soils and aquatic environments, can catalyze the oxidation of Mn(II) and accelerate the formation of high-valence Mn, which can significantly influence the speciation, toxicity, and mobility of As when these species co-exist. In this context, we herein explored the mechanism of As(III) oxidation in the presence of ferrihydrite and Mn(II) using a kinetic approach combined with multiple spectroscopic techniques, including X-ray absorption near edge spectroscopy, in situ horizontal attenuated total-reflectance Fourier transform infrared spectroscopy, and in situ quick scanning X-ray absorption spectroscopy. Our results indicate that efficient As(III) oxidation by dissolved O 2 occurs on the surface of ferrihydrite in the presence of aqueous Mn(II). Compared with As(III) oxidation in the presence of ferrihydrite and Mn oxides (i.e., Mn oxides/hydroxides), the degree of As(III) oxidation in the ferrihydrite-Mn(II) system was significantly higher, and the majority of generated As(V) was adsorbed on the mineral (i.e., ferrihydrite) surface. Furthermore, As(III) oxidation was enhanced upon increasing both the molar ratio of Mn(II)/As(III) and the solution pH. The greater As(III) oxidation by O 2 in the ferrihydrite-Mn(II) system was mainly attributed to the formation of a strong oxidant of the instantaneous intermediate Mn(III) species via Mn(II) oxidation under catalysis by the ferrihydrite surface. Moreover, As(III) oxidation occurred mainly on the ferrihydrite surface and was accompanied by the regeneration of Mn(II), thereby rendering it recyclable. These results therefore provide new insights into the mechanism of As(III) oxidation on the surfaces of Fe oxides (i.e., Fe oxides/hydroxides) in the presence of aqueous Mn(II) as

  11. Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater

    Science.gov (United States)

    Bohu, Tsing; Akob, Denise M.; Abratis, Michael; Lazar, Cassandre S.; Küsel, Kirsten

    2016-01-01

    The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems.

  12. The Enzymatic Oxidation of Graphene Oxide

    Science.gov (United States)

    Kotchey, Gregg P.; Allen, Brett L.; Vedala, Harindra; Yanamala, Naveena; Kapralov, Alexander A.; Tyurina, Yulia Y.; Klein-Seetharaman, Judith; Kagan, Valerian E.; Star, Alexander

    2011-01-01

    Two-dimensional graphitic carbon is a new material with many emerging applications, and studying its chemical properties is an important goal. Here, we reported a new phenomenon – the enzymatic oxidation of a single layer of graphitic carbon by horseradish peroxidase (HRP). In the presence of low concentrations of hydrogen peroxide (~40 µM), HRP catalyzed the oxidation of graphene oxide, which resulted in the formation of holes on its basal plane. During the same period of analysis, HRP failed to oxidize chemically reduced graphene oxide (RGO). The enzymatic oxidation was characterized by Raman, UV-Vis, EPR and FT-IR spectroscopy, TEM, AFM, SDS-PAGE, and GC-MS. Computational docking studies indicated that HRP was preferentially bound to the basal plane rather than the edge for both graphene oxide and RGO. Due to the more dynamic nature of HRP on graphene oxide, the heme active site of HRP was in closer proximity to graphene oxide compared to RGO, thereby facilitating the oxidation of the basal plane of graphene oxide. We also studied the electronic properties of the reduced intermediate product, holey reduced graphene oxide (hRGO), using field-effect transistor (FET) measurements. While RGO exhibited a V-shaped transfer characteristic similar to a single layer of graphene that was attributed to its zero band gap, hRGO demonstrated a p-type semiconducting behavior with a positive shift in the Dirac points. This p-type behavior rendered hRGO, which can be conceptualized as interconnected graphene nanoribbons, as a potentially attractive material for FET sensors. PMID:21344859

  13. FTIR Spectroscopic Study of Mn(II) Oxidizing Pseudomonas putida GB1 Biofilms on ZnSe, Ge, and CdTe Crystal Surfaces

    Science.gov (United States)

    Parikh, S. J.; Gilbert, H. L.; Conklin, M. H.; Chorover, J.

    2003-12-01

    Pseudomonas putida strain GB1 is an aerobic, gram-negative bacterium capable of gaining energy from the biological oxidation of Mn(II). The increased kinetics of Mn(II) oxidation resulting from this microbial catalysis is known to contribute to the formation of Mn(IV) oxides in natural waters. Environmental conditions, including aqueous and surface chemistry, greatly affect the macromolecular composition and surface adhesion behavior of bacteria. For example, the chemistry of GB1 biofilms forming on crystal surfaces is expected to vary with Mn(II) concentration in solution. We used Fourier transform infrared (FTIR) spectroscopy to probe the formation of GB1 biofilms on the surfaces of negatively-charged IR transparent ZnSe, Ge, and CdTe crystal windows. Bacterial adhesion experiments were carried out both in the presence and absence of Mn(II)(aq) with FTIR windows suspended in a bioreactor comprising GB1 cells in a mineral growth medium at pH 7.6 and 30° C. After 85 h, windows were removed from the reactor and IR spectra were collected. Oxidation of Mn(II) was confirmed via leucoberbelin blue (LBB) indicator and the appearance of Mn-O stretches in biofilm IR spectra. Transmission FTIR spectra do not reveal detectable effects of crystal type on biofilm composition, but do indicate changes in chemistry resulting from introduction of Mn(II). In the presence of Mn(II), spectra of biofilms show higher relative intensity in the carbohydrate region (specifically 1160, 1052 cm-1). A down frequency shift in the P=O absorbance was also observed (1240 to 1222 cm-1). These results indicate a modification of bacterial cell/biofilm composition resulting during biological oxidation of Mn(II). The CdTe transmission window permits measurements to low wavenumbers (treatment. Transmission electron microscopy (TEM) of the bioreactor suspension revealed needle-like clusters of Mn oxide crystals in association with GB1 biomass and extracellular materials.

  14. High turnover catalysis of water oxidation by Mn(II) complexes of monoanionic pentadentate ligands.

    Science.gov (United States)

    Seidler-Egdal, Rune Kirk; Nielsen, Anne; Bond, Andrew D; Bjerrum, Morten J; McKenzie, Christine J

    2011-04-21

    Capillary electrophoresis (CE) and electrospray ionisation (ESI) mass spectra of aqueous solutions of manganese(II) complexes of the monoanions of the pentadentate ligands N-methyl-N'-carboxymethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine (mcbpen(-)) and N-benzyl-N'-carboxymethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine (bcbpen(-)), show the presence of a mixture of closely related Mn(II) species, assigned to the mono, di-, tri- and poly-cationic complexes [Mn(II)(L)(H(2)O)](n)(n+), L = mcbpen(-) or bcbpen(-) with n = 1, 2, 3, etc. In solution, these complexes are reversibly oxidized by tert-butyl hydrogen peroxide (TBHP), (NH(4))(2)[Ce(NO(3))(6)], Ce(ClO(4))(4), oxone and [Ru(bipy)(3)](3+) to form metastable (t(½) = min to h) higher valent (hydr)oxide species, showing a collective maximum absorbance at 430 nm. The same species can be produced by [Ru(bipy)(3)](2+)-mediated photooxidization in the presence of an electron acceptor. TBHP oxidation of the complexes, in large excesses of the TBHP, is concurrent with an O(2) evolution with turnovers of up to 1.5 × 10(4) mol of O(2) per mol of [Mn] and calculated rate constants from two series of experiments of 0.039 and 0.026 mol[O(2)] s(-1) M(-2). A 1:1 reaction of TBHP with [Mn] is rate determining and the resultant species is proposed to be the mononuclear, catalytically competent, [Mn(IV)(O)(mcbpen)](+). At very close m/z values [Mn(III)(OH)(mcbpen)](+), [Mn(2)(III/IV)(O)(2)(mcbpen)(2)](+) and [Mn(IV)(2)(O)(2)(mcbpen)(2)](2+) are detected by ESI MS and CE when the concentration of TBHP is comparable to or lower than that of [Mn]. These are conditions that occur post catalysis and these species are derived from [Mn(IV)(O)(mcbpen)](+) through condensation reactions.

  15. Multicopper Oxidase Involvement in Both Mn(II) and Mn(III) Oxidation during Bacterial Formation of MnO2

    OpenAIRE

    Soldatova, Alexandra V.; Butterfield, Cristina; Oyerinde, Oyeyemi F.; Tebo, Bradley M.; Spiro, Thomas G.

    2012-01-01

    Global cycling of environmental manganese requires catalysis by bacteria and fungi for MnO2 formation, since abiotic Mn(II) oxidation is slow under ambient conditions. Genetic evidence from several bacteria implicates multicopper oxidases (MCOs) as being required for MnO2 formation. However, MCOs catalyze one-electron oxidations, whereas conversion of Mn(II) to MnO2 is a two-electron process. Trapping experiments with pyrophosphate (PP), a Mn(III) chelator, have demonstrated that Mn(III) is a...

  16. Conditions for the formation of pure birnessite during the oxidation of Mn(II) cations in aqueous alkaline medium

    Energy Technology Data Exchange (ETDEWEB)

    Boumaiza, Hella [Laboratoire de Chimie des Matériaux et Catalyse, Faculté des Sciences de Tunis, Université El Manar (Tunisia); Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME)-UMR 7564, CNRS-Université de Lorraine, 405, rue de Vandoeuvre, 54600 Villers-lès-Nancy (France); Département de Génie Biologique et Chimique, Institut National des Sciences Appliquées et de Technologies (INSAT), Université de Carthage, Tunis (Tunisia); Coustel, Romain [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME)-UMR 7564, CNRS-Université de Lorraine, 405, rue de Vandoeuvre, 54600 Villers-lès-Nancy (France); Medjahdi, Ghouti [Institut Jean Lamour, Centre de Compétences Rayons X et Spectroscopie (X-Gamma), UMR 7198 CNRS-Université de Lorraine (France); Ruby, Christian, E-mail: Christian.ruby@univ-lorraine.fr [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME)-UMR 7564, CNRS-Université de Lorraine, 405, rue de Vandoeuvre, 54600 Villers-lès-Nancy (France); and others

    2017-04-15

    Birnessite was synthetized through redox reaction by mixing MnO{sub 4}{sup -}, Mn{sup 2+} and OH{sup -} solutions. The Mn(VII): Mn(II) ratio of 0.33 was chosen and three methods were used consisting in a quick mixing under vigorous stirring of two of the three reagents and then on the dropwise addition of the third one. The obtained solids were characterized by XRD, FTIR and XPS spectroscopies. Their average oxidation states were determined from ICP and CEC measurements while their surface properties were investigated by XPS. This study provides an increased understanding of the importance of dissolved oxygen in the formation of birnessite and hausmannite and shows the ways to obtain pure birnessite. The role of counter-ion ie. Na{sup +} or K{sup +} was also examined. - Graphical abstract: Pathways of birnessite formation. - Highlights: • Pure birnessite is prepared through a redox reaction. • Hausmannite formation is prevented by controlling dissolved O2. • The employed counterion influences the purity of birnessite. • Initial Mn(OH){sub 2} is oxidized by both MnO{sub 4}{sup -} and dissolved O{sub 2}.

  17. Kinetics and Mechanism of Mn(II Catalyzed Periodate Oxidation of p-anisidine: Effect of pH

    Directory of Open Access Journals (Sweden)

    Rajneesh Dutt Kaushik

    2014-10-01

    Full Text Available The stoichiometry for the initial part of the reaction, Mn(II catalysed periodate oxidation of p-anisidine (PMA, has been found to be 1 mol of PMA consuming 2 mol of periodate ion. The kinetic-mechanistic study of reaction in acetone-water medium was made spectrophotometrically by noting the increase in the absorbance of reaction intermediate. Reaction is first order in reactants and catalyst each. A decrease in dielectric constant of the medium results in decrease in the rate of reaction suggesting an ion-dipole type interaction. Free radical scavengers do not affect the reaction rate. A special type of rate-pH profile shows a maximum at pH = 7.0. This pH effect also suggests the involvement of at least three differently reactive reactant species in the reaction and this fact has been considered by us while deriv-ing the rate law. Under pseudo first order conditions [IO4-] >> [PMA] and in agreement with the derived rate law, the 1/kcat versus [H+] plot passes through the minimum and the results can be fitted to the equation: 1/kcat = (K2 / k K3 K4 [H+] + {(Kw + Kb K2 / k K3 K4 Kw} + Kb [H+] / k K3 K4 Kw, where kK3K4 is the empirical composite rate constant, Kw is ionic product of water, K2 is acid dissociation constant of H4IO6- and Kb is base dissociation constant of PMA. The experimental value of [H+]min is in good agreement with the value calculated by using the derived rate law equation and is character-istic of the substrate involved relating to the base dissociation constant of PMA. The value of thermo-dynamic parameters have been evaluated. © 2014 BCREC UNDIP. All rights reservedReceived: 2nd May 2014; Revised: 2nd July 2014; Accepted: 5th July 2014How to Cite: Kaushik, R.D., Singh, J., Manila, M., Kaur, M., Singh, P. (2014. Kinetics and Mechanism of MnII Catalyzed Periodate Oxidation of p-anisidine: Effect of pH. Bulletin of Chemical Reaction En-gineering & Catalysis, 9(3: 182-191. (doi: 10.9767/bcrec.9.3.6823.182-191Permalink

  18. High Turnover Catalysis of Water Oxidation by Mn(II) complexes of Monoanionic Pentadentate Ligands

    DEFF Research Database (Denmark)

    Seidler-Egdal, Rune Kirk; Nielsen, Anne; Bond, Andrew

    2011-01-01

    peroxide (TBHP), (NH4)2[Ce(NO3)6], Ce(ClO4)4, oxone and [Ru(bipy)3]3+ to form metastable (t½ = min to h) higher valent (hydr)oxide species, showing a collective maximum absorbance at 430 nm. The same species can be produced by [Ru(bipy)3]2+-mediated photooxidization in the presence of an electron acceptor....... TBHP oxidation of the complexes, in large excesses of the TBHP, is concurrent with an O2 evolution with turnovers of up to 1.5 × 104 mol of O2 per mol of [Mn] and calculated rate constants from two series of experiments of 0.039 and 0.026 mol[O2] s−1 M−2. A 1:1 reaction of TBHP with [Mn] is rate...

  19. High turnover catalysis of water oxidation by Mn(II) complexes of monoanionic pentadentate ligands

    DEFF Research Database (Denmark)

    Seidler-Egdal, Rune Kirk; Nielsen, Anne; Bond, Andrew

    2011-01-01

    -butyl hydrogen peroxide (TBHP), (NH(4))(2)[Ce(NO(3))(6)], Ce(ClO(4))(4), oxone and [Ru(bipy)(3)](3+) to form metastable (t(½) = min to h) higher valent (hydr)oxide species, showing a collective maximum absorbance at 430 nm. The same species can be produced by [Ru(bipy)(3)](2+)-mediated photooxidization...... in the presence of an electron acceptor. TBHP oxidation of the complexes, in large excesses of the TBHP, is concurrent with an O(2) evolution with turnovers of up to 1.5 × 10(4) mol of O(2) per mol of [Mn] and calculated rate constants from two series of experiments of 0.039 and 0.026 mol[O(2)] s(-1) M(-2). A 1...

  20. Zeolite-encapsulated Co(II), Mn(II), Cu(II) and Cr(III) salen complexes as catalysts for efficient selective oxidation of benzyl alcohol

    Science.gov (United States)

    Li, F. H.; Bi, H.; Huang, D. X.; Zhang, M.; Song, Y. B.

    2018-01-01

    Co(II), Mn(II), Cu(II) and Cr(III) salen type complexes were synthesized in situ in Y zeolite by the reaction of ion-exchanged metal ions with the flexible ligand molecules that had diffused into the cavities. Data of characterization indicates the formation of metal salen complexes in the pores without affecting the zeolite framework structure, the absence of any extraneous species and the geometry of encapsulated complexes. The catalytic activity results show that Cosalcyen Y exhibited higher catalytic activity in the water phase selective oxidation of benzyl alcohol, which could be attributed to their geometry and the steric environment of the metal actives sites.

  1. Effects of exogenous pyoverdines on Fe availability and their impacts on Mn(II) oxidation by Pseudomonas putida GB-1

    Science.gov (United States)

    Lee, Sung-Woo; Parker, Dorothy L.; Geszvain, Kati; Tebo, Bradley M.

    2014-01-01

    Pseudomonas putida GB-1 is a Mn(II)-oxidizing bacterium that produces pyoverdine-type siderophores (PVDs), which facilitate the uptake of Fe(III) but also influence MnO2 formation. Recently, a non-ribosomal peptide synthetase mutant that does not synthesize PVD was described. Here we identified a gene encoding the PVDGB-1 (PVD produced by strain GB-1) uptake receptor (PputGB1_4082) of strain GB-1 and confirmed its function by in-frame mutagenesis. Growth and other physiological responses of these two mutants and of wild type were compared during cultivation in the presence of three chemically distinct sets of PVDs (siderotypes n°1, n°2, and n°4) derived from various pseudomonads. Under iron-limiting conditions, Fe(III) complexes of various siderotype n°1 PVDs (including PVDGB-1) allowed growth of wild type and the synthetase mutant, but not the receptor mutant, confirming that iron uptake with any tested siderotype n°1 PVD depended on PputGB1_4082. Fe(III) complexes of a siderotype n°2 PVD were not utilized by any strain and strongly induced PVD synthesis. In contrast, Fe(III) complexes of siderotype n°4 PVDs promoted the growth of all three strains and did not induce PVD synthesis by the wild type, implying these complexes were utilized for iron uptake independent of PputGB1_4082. These differing properties of the three PVD types provided a way to differentiate between effects on MnO2 formation that resulted from iron limitation and others that required participation of the PVDGB-1 receptor. Specifically, MnO2 production was inhibited by siderotype n°1 but not n°4 PVDs indicating PVD synthesis or PputGB1_4082 involvement rather than iron-limitation caused the inhibition. In contrast, iron limitation was sufficient to explain the inhibition of Mn(II) oxidation by siderotype n°2 PVDs. Collectively, our results provide insight into how competition for iron via siderophores influences growth, iron nutrition and MnO2 formation in more complex environmental

  2. Fingerprinting Bacterial and Fungal Manganese Oxidation via Stable Oxygen Isotopes of Manganese Oxides

    Science.gov (United States)

    Sutherland, K. M.; Wankel, S. D.; Hansel, C. M.

    2016-12-01

    Manganese (Mn) oxides are a ubiquitous mineralogical component of surface Earth and Mars. Mn(III/IV) oxides are potent environmental sorbents and oxidants that play a crucial role in the fate of organic matter. The processes by which Mn(II) oxidation occurs in natural systems are poorly understood, but a number of studies have implicated microogranisms as the primary agents of Mn(II) oxidation in terrestrial and marine environments. The ability of microorganisms to oxidize Mn(II) to Mn(III/IV) oxides transcends the boundaries of biological domain, with an abundance of well-characterized prokaryotes as well as eukaryotic fungi with the ability to oxidize Mn(II) to Mn(III/IV) oxides. Biological Mn(II) oxidation proceeds directly through enzymatic activity or indirectly through the production of reactive oxygen species. Building upon earlier research suggesting that stable oxygen isotope fractionation could be used to fingerprint unique Mn(II)-oxidizing organisms or distinct oxidation pathways, here we use culture-based studies of Mn(II)-oxidizing bacteria and fungi to determine the kinetic oxygen isotope effects associated with Mn(II) oxidation. Since the oxygen molecules in Mn(III/IV) oxides are comprised of oxygen from both precursor water and molecular oxygen, we used a two-fold approach to constrain isotope fractionation with respect to each oxygen source. We used open system oxidation experiments using oxygen-18 labeled water in parallel with closed system Rayleigh distillation oxidation experiments to fully constrain isotope fractionation associated with oxygen atom incorporation during Mn(II) oxidation. Our results suggest commonalities among fractionation factors from groups of Mn(II)-oxidizing organisms that have similar oxidation mechanisms. These results suggest that stable oxygen isotopes of Mn(III/IV) oxides have the potential to distinguish between Mn(II) oxidation pathways in nature, providing a way to determine which groups of Mn(II) oxidizers may be

  3. A Mn(II) complex of boradiazaindacene (BODIPY) loaded graphene oxide as both LED light and H2O2 enhanced anticancer agent.

    Science.gov (United States)

    Xu, Xiao-Lei; Shao, Jian; Chen, Qiu-Yun; Li, Cheng-Hao; Kong, Meng-Yun; Fang, Fang; Ji, Ling; Boison, Daniel; Huang, Tao; Gao, Jing; Feng, Chang-Jian

    2016-06-01

    Cancer cells are more susceptible to H2O2 induced cell death than normal cells. H2O2-activatable and O2-evolving nanoparticles could be used as photodynamic therapy agents in hypoxic environments. In this report, a photo-active Mn(II) complex of boradiazaindacene derivatives (Mn1) was used as a dioxygen generator under irradiation with LED light in water. Moreover, the in vitro biological evaluation for Mn1 and its loaded graphene oxide (herein called Mn1@GO) on HepG-2 cells in normal and hypoxic conditions has been performed. In particular, Mn1@GO can react with H2O2 resulting active anticancer species, which show high inhibition on both HepG-2 cells and CoCl2-treated HepG-2 cells (hypoxic cancer cells). The mechanism of LED light enhanced anticancer activity for Mn1@GO on HepG-2 cells was discussed. Our results show that Mn(II) complexes of boradiazaindacene (BODIPY) derivatives loaded GO can be both LED light and H2O2-activated anticancer agents in hypoxic environments. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Nitric oxide synthase expression and enzymatic activity in multiple sclerosis

    DEFF Research Database (Denmark)

    Broholm, H; Andersen, B; Wanscher, B

    2004-01-01

    and endothelial nitric oxide synthase (NOS)], and enzymatic NO synthase activity. MRI guided biopsies documented more active plaques than macroscopic examination, and histological examination revealed further lesions. Inducible NOS (iNOS) was the dominant IR isoform, while reactive astrocytes were the dominant i...

  5. Evaluation of wet oxidation pretreatment for enzymatic hydrolysis of softwood

    DEFF Research Database (Denmark)

    Palonen, H.; Thomsen, A.B.; Tenkanen, M.

    2004-01-01

    , and the compositions of solid and liquid fractions were analyzed. The solid fraction after wet oxidation contained 58-64% cellulose, 2-16% hemicellulose, and 24-30% lignin. The pretreatment series gave information about the roles of lignin and hemicellulose in the enzymatic hydrolysis. The temperature...... of the pretreatment, the residual hemicellulose content of the substrate, and the type of the commercial cellulase preparation used were the most important factors affecting the enzymatic hydrolysis. The highest sugar yield in a 72-h hydrolysis, 79% of theoretical, was obtained using a pretreatment of 200degrees...

  6. Coulometric titration of D(+)-glucose using its enzymatic oxidation.

    Science.gov (United States)

    Tanaka, T; Shutto, E; Mizoguchi, T; Fukushima, K

    2001-02-01

    A definitive method is described for the indirect assay of milligram quantities of D(+)-glucose by coulometric titration. D(+)-Glucose was aerobically oxidized by glucose oxidase in an acetate buffer solution (pH 5.1). Subsequently, the enzymatically formed hydrogen peroxide was titrated coulometrically with electrogenerated hypobromite in sodium bromide-sodium tetraborate medium of pH 8.6, with biamperometric end-point detection. Parameters affecting the enzymatically catalyzed oxidation and coulometric titration were evaluated. The optimized conditions for the oxidation of up to 20 mg of D(+)-glucose include the addition of 4500 U of glucose oxidase and stirring over a 10-min interval at 25 degrees C. Under proposed conditions, the assay values of several commercial D(+)-glucose reagents were somewhat lower than the guaranteed minimum values, with RSDs (n = 5) of 0.071 - 0.106%.

  7. Secretome-based Manganese(II) Oxidation by Filamentous Ascomycete Fungi

    Science.gov (United States)

    Zeiner, C. A.; Purvine, S.; Zink, E.; Paša-Tolić, L.; Chaput, D.; Wu, S.; Santelli, C. M.; Hansel, C. M.

    2017-12-01

    Manganese (Mn) oxides are among the strongest oxidants in the environment, and Mn(II) oxidation to Mn(III/IV) (hydr)oxides includes both abiotic and microbially-mediated processes. While white-rot Basidiomycete fungi oxidize Mn(II) using laccases and Mn peroxidases in association with lignocellulose degradation, the mechanisms by which filamentous Ascomycete fungi oxidize Mn(II) and a physiological role for Mn(II) oxidation in these organisms remain poorly understood. Through a combination of chemical and in-gel assays, bulk mass spectrometry, and iTRAQ proteomics, we demonstrate enzymatic Mn(II) oxidation in the secretomes of three phylogenetically diverse Ascomycetes that were isolated from Mn-laden sediments. Candidate Mn(II)-oxidizing enzymes were species-specific and included bilirubin oxidase and tyrosinase in Stagonospora sp. SRC1lsM3a, GMC oxidoreductase in Paraconiothyrium sporulosum AP3s5-JAC2a, and FAD-binding oxidoreductases in Pyrenochaeta sp. DS3sAY3a. These findings were supported by full proteomic characterization of the secretomes, which revealed a lack of Mn, lignin, and versatile peroxidases in these Ascomycetes but a substantially higher proportion of LMCOs and GMC oxidoreductases compared to wood-rot Basidiomycetes. We also identified the potential for indirect enzymatic Mn(II) oxidation by hydroxyl radical, as the secretomes were rich in diverse lignocellulose-degrading enzymes that could participate in Fenton chemistry. A link between Mn(II) oxidation and carbon oxidation analogous to white-rot Basidiomycetes remains unknown in these Ascomycetes. Interestingly, growth rates on rich medium were unaffected by the presence of Mn(II), and the production of Mn(II)-oxidizing proteins in the secretome was constitutive and not inducible by Mn(II). Thus, no physiological benefit of Mn(II) oxidation in these Ascomycetes has yet been identified, and Mn(II) oxidation appears to be a side reaction. Future work will explore the lignin-degrading capacity of

  8. Oxidative enzymatic gelation of sugar beet pectin for emulsion stabilization

    DEFF Research Database (Denmark)

    Abang Zaidel, Dayang Norulfairuz; Meyer, Anne S.

    2013-01-01

    Pectin from sugar beet is derived from the sugar beet pulp residue which results when sugar beets are processed for sucrose extraction. The sugar beet pectin has poor gelationability by the classic divalentcation molecular mechanism because of a relatively high acetylation degree and short...... emulsions has recently been investigated in model food emulsions. This paper reviews the pectin chemistry, enzymatic oxidative gelation mechanisms, interaction mechanisms of the sugar beet pectin with the emulsion droplets and explores how the gelation affects the rheology and stability of emulsion systems...

  9. Identification of a Third Mn(II) Oxidase Enzyme in Pseudomonas putida GB-1.

    Science.gov (United States)

    Geszvain, Kati; Smesrud, Logan; Tebo, Bradley M

    2016-07-01

    The oxidation of soluble Mn(II) to insoluble Mn(IV) is a widespread bacterial activity found in a diverse array of microbes. In the Mn(II)-oxidizing bacterium Pseudomonas putida GB-1, two Mn(II) oxidase genes, named mnxG and mcoA, were previously identified; each encodes a multicopper oxidase (MCO)-type enzyme. Expression of these two genes is positively regulated by the response regulator MnxR. Preliminary investigation into putative additional regulatory pathways suggested that the flagellar regulators FleN and FleQ also regulate Mn(II) oxidase activity; however, it also revealed the presence of a third, previously uncharacterized Mn(II) oxidase activity in P. putida GB-1. A strain from which both of the Mn(II) oxidase genes and fleQ were deleted exhibited low levels of Mn(II) oxidase activity. The enzyme responsible was genetically and biochemically identified as an animal heme peroxidase (AHP) with domain and sequence similarity to the previously identified Mn(II) oxidase MopA. In the ΔfleQ strain, P. putida GB-1 MopA is overexpressed and secreted from the cell, where it actively oxidizes Mn. Thus, deletion of fleQ unmasked a third Mn(II) oxidase activity in this strain. These results provide an example of an Mn(II)-oxidizing bacterium utilizing both MCO and AHP enzymes. The identity of the Mn(II) oxidase enzyme in Pseudomonas putida GB-1 has been a long-standing question in the field of bacterial Mn(II) oxidation. In the current work, we demonstrate that P. putida GB-1 employs both the multicopper oxidase- and animal heme peroxidase-mediated pathways for the oxidation of Mn(II), rendering this model organism relevant to the study of both types of Mn(II) oxidase enzymes. The presence of three oxidase enzymes in P. putida GB-1 deepens the mystery of why microorganisms oxidize Mn(II) while providing the field with the tools necessary to address this question. The initial identification of MopA as a Mn(II) oxidase in this strain required the deletion of FleQ, a

  10. Oxidative enzymatic gelation of sugar beet pectin for emulsion stabilization

    DEFF Research Database (Denmark)

    Abang Zaidel, Dayang Norulfairuz; Meyer, Anne S.

    2013-01-01

    Pectin from sugar beet is derived from the sugar beet pulp residue which results when sugar beets are processed for sucrose extraction. The sugar beet pectin has poor gelationability by the classic divalentcation molecular mechanism because of a relatively high acetylation degree and short...... polygalacturonate backbone chain length. However, due to the feruloyl-substitutions on the side chains, the sugar beet pectic polysaccharides can be cross-linked via enzyme catalyzed oxidation. The enzyme kinetics and functionality of such oxidativelycross-linked sugar beet pectin, in relation to stabilizing...... emulsions has recently been investigated in model food emulsions. This paper reviews the pectin chemistry, enzymatic oxidative gelation mechanisms, interaction mechanisms of the sugar beet pectin with the emulsion droplets and explores how the gelation affects the rheology and stability of emulsion systems...

  11. Effect of nitrogen oxide pretreatments on enzymatic hydrolysis of cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Borrevik, R.K.; Wilke, C.R.; Brink, D.L.

    1978-09-01

    This work considers the effect of nitrogen oxide pretreatments on the subsequent enzymatic hydrolysis by Trichoderma viride cellulase of the cellulose occurring in wheat straw; Triticum Aestivum-L, em. Thell. In the pretreatment scheme the straw is first reacted with nitric oxide and air, and then extracted in aqueous solution. In this way, overall sugar yields increased from 17% for the case of no pretreatment to 70%. The glucose yield increased from 20 to 60%. The yield of glucose during enzymatic hydrolysis is dependent on the reaction time of the gas phase reaction. For a 24 hour reaction the yield is 60%, but drops to 45% for a reaction time of 2 hours. Xylose, a potentially valuable side product of the pretreatment, is obtained by dilute acid hydrolysis during the extraction stage in yields of 90 to 96%. In acidic media, the kinetics of both the rate of formation and destruction of xylose were found to follow the first-order rate laws reported in the literature. These were determined to be 4.5 (liter/gmole)(hr./sup -1/) and 0.03 hr./sup -1/, respectively. However, the rate of formation is much greater (20.4 (liter/gmole) (hr./sup -1/)) when the extraction liquor is recycled. The most likely explanation for this is that the increased total acidity of the recycled liquor compensates for diffusional limitations. A preliminary design and cost analysis of the pretreatment-hydrolysis scheme indicates that glucose can be produced at 10.86 cents per pound, exclusive of straw cost. The corresponding cost per pound of total sugars produced is 5.0 cents. Sensitivity analyses indicate that 42% of the pretreatment cost (excluding hydrolysis) can be attributed to nitric oxide production, and the high yield of sugar obtained is advantageous when considering the cost of straw.

  12. Controlling enzymatic activity by immobilization on graphene oxide

    Science.gov (United States)

    Bolibok, Paulina; Wiśniewski, Marek; Roszek, Katarzyna; Terzyk, Artur P.

    2017-04-01

    In this study, graphene oxide (GO) has been applied as a matrix for enzyme immobilization. The protein adsorption capacity of GO is much higher than of other large surface area carbonaceous materials. Its structure and physicochemical properties are reported beneficial also for enzymatic activity modifications. The experimental proof was done here that GO-based biocatalytic systems with immobilized catalase are modifiable in terms of catalyzed reaction kinetic constants. It was found that activity and stability of catalase, considered here as model enzyme, closely depend on enzyme/GO ratio. The changes in kinetic parameters can be related to secondary structure alterations. The correlation between enzyme/GO ratio and kinetic and structure parameters is reported for the first time and enables the conscious control of biocatalytic processes and their extended applications. The biological activity of obtained biocatalytic systems was confirmed in vitro by the use of functional test. The addition of immobilized catalase improved the cells' viability after they were exposed to hydrogen peroxide and tert-butyl-hydroperoxide used as source of reactive oxygen species.

  13. Rapid reaction of nanomolar Mn(II) with superoxide radical in seawater and simulated freshwater.

    Science.gov (United States)

    Hansard, S Paul; Easter, Hillary D; Voelker, Bettina M

    2011-04-01

    Superoxide radical (O2-) has been proposed to be an important participant in oxidation-reduction reactions of metal ions in natural waters. Here, we studied the reaction of nanomolar Mn(II) with O2- in seawater and simulated freshwater, using chemiluminescence detection of O2- to quantify the effect of Mn(II) on the decay kinetics of O2-. With 3-24 nM added [Mn(II)] and seawater samples. In simulated freshwater (pH 8.6), the effective rate constant of Mn(II) reaction with O2- was somewhat lower, 1.6×10(6) M(-1)·s(-1). With higher initial [O2-], in excess of added [Mn(II)], catalytic decay of O2- by Mn was observed, implying that a Mn(II/III) redox cycle occurred. Our results show that reactions with nanomolar Mn(II) could be an important sink of O2- in natural waters. In addition, reaction of Mn(II) with superoxide could maintain a significant fraction of dissolved Mn in the +III oxidation state.

  14. Rapid reaction of nanomolar Mn(II) with superoxide radical in seawater and simulated freshwater

    Science.gov (United States)

    Hansard, S.P.; Easter, H.D.; Voelker, Bettina M.

    2011-01-01

    Superoxide radical (O2-) has been proposed to be an important participant in oxidation-reduction reactions of metal ions in natural waters. Here, we studied the reaction of nanomolar Mn(II) with O 2- in seawater and simulated freshwater, using chemiluminescence detection of O2- to quantify the effect of Mn(II) on the decay kinetics of O2-. With 3-24 nM added [Mn(II)] and seawater samples. In simulated freshwater (pH 8.6), the effective rate constant of Mn(II) reaction with O 2- was somewhat lower, 1.6 ?? 106 M -1???s-1. With higher initial [O2-], in excess of added [Mn(II)], catalytic decay of O 2- by Mn was observed, implying that a Mn(II/III) redox cycle occurred. Our results show that reactions with nanomolar Mn(II) could be an important sink of O2- in natural waters. In addition, reaction of Mn(II) with superoxide could maintain a significant fraction of dissolved Mn in the +III oxidation state. ?? 2011 American Chemical Society.

  15. Enzymatically synthesized glycogen inhibits colitis through decreasing oxidative stress.

    Science.gov (United States)

    Mitani, Takakazu; Yoshioka, Yasukiyo; Furuyashiki, Takashi; Yamashita, Yoko; Shirai, Yasuhito; Ashida, Hitoshi

    2017-05-01

    Inflammatory bowel diseases are a group of chronic inflammation conditions of the gastrointestinal tract. Disruption of the mucosal immune response causes accumulation of oxidative stress, resulting in the induction of inflammatory bowel disease. In this study, we investigated the effect of enzymatically synthesized glycogen (ESG), which is produced from starch, on dextran sulfate sodium (DSS)- and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in C57BL/6 mice. Oral administration of ESG suppressed DSS- and TNBS-induced shortening of large intestine in female mice and significant decreased DSS-induced oxidative stress and TNBS-induced pro-inflammatory cytokine expression in the large intestine. ESG increase in the expression levels of heme oxygenase-1 (HO-1) and NF-E2-related factor-2 (Nrf2), a transcription factor for HO-1 expressed in the large intestine. Furthermore, ESG-induced HO-1 and Nrf2 were expressed mainly in intestinal macrophages. ESG is considered to be metabolized to resistant glycogen (RG) during digestion with α-amylase in vivo. In mouse macrophage RAW264.7 cells, RG, but not ESG decreased 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced reactive oxygen species (ROS). Knockdown of Nrf2 inhibited RG-induced HO-1 expression and negated the decrease in AAPH-induced ROS brought about by RG. RG up-regulated the protein stability of Nrf2 to decrease the formation of Nrf2-Keap1 complexes. RG-induced phosphorylation of Nrf2 at Ser40 was suppressed by ERK1/2 and JNK inhibitors. Our data indicate that ESG, digested with α-amylase to RG, suppresses DSS- and TNBS-induced colitis by increasing the expression of HO-1 in the large intestine of mice. Furthermore, we demonstrate that RG induces HO-1 expression by promoting phosphorylation of Nrf2 at Ser40 through activation of the ERK1/2 and JNK cascade in macrophages. Copyright © 2017. Published by Elsevier Inc.

  16. Lignocellulose pretreatment technologies affect the level of enzymatic cellulose oxidation by LPMO

    DEFF Research Database (Denmark)

    Rodríguez-Zúñiga, Ursula Fabiola; Cannella, David; de Campos Giordano, Roberto

    2015-01-01

    Sugarcane bagasse, corn stover, and wheat straw are among the most available resources for production of cellulosic ethanol. For these biomasses we study the influence of pre-treatment methods on the chemical composition, as well as on the subsequent reactions of enzymatic hydrolysis and oxidation...

  17. Pretreatment of corn stover using wet oxidation to enhance enzymatic digestibility

    DEFF Research Database (Denmark)

    Varga, E.; Schmidt, A.S.; Reczey, K.

    2003-01-01

    Corn stover is an abundant, promising raw material for fuel ethanol production. Although it has a high cellulose content, without pretreatment it resists enzymatic hydrolysis, like most lignocellulosic materials. Wet oxidation (water, oxygen, mild alkali or acid, elevated temperature and pressure...

  18. Simultaneous iridium catalysed oxidation and enzymatic reduction employing orthogonal reagents

    NARCIS (Netherlands)

    Mutti, Francesco G.; Orthaber, Andreas; Schrittwieser, Joerg H.; Vries, Johannes G. de; Pietschnig, Rudolf; Kroutil, Wolfgang

    2010-01-01

    An iridium catalysed oxidation was coupled concurrently to an asymmetric biocatalytic reduction in one-pot; thus it was shown for the first time that iridium- and alcohol dehydrogenase-catalysed redox reactions are compatible. As a model system racemic chlorohydrins were transformed to

  19. Complete genome sequence of the highly Mn(II) tolerant Staphylococcus sp. AntiMn-1 isolated from deep-sea sediment in the Clarion-Clipperton Zone.

    Science.gov (United States)

    Wang, Xing; Lin, Danqiu; Jing, Xiaohuan; Zhu, Sidong; Yang, Jifang; Chen, Jigang

    2018-01-20

    Staphylococcus sp. AntiMn-1 is a deep-sea bacterium inhabiting seafloor sediment in the Clarion-Clipperton Zone (CCZ) that is highly tolerant to Mn(II) and displays efficient Mn(II) oxidation. Herein, we present the assembly and annotation of its genome. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Nitric oxide synthase expression and enzymatic activity in multiple sclerosis

    DEFF Research Database (Denmark)

    Broholm, H; Andersen, B; Wanscher, B

    2004-01-01

    We used post-mortem magnetic resonance imaging (MRI) guidance to obtain paired biopsies from the brains of four patients with clinical definite multiple sclerosis (MS). Samples were analyzed for the immunoreactivity (IR) of the three nitric oxide (NO) synthase isoforms [inducible, neuronal...... and sex showed no such changes. Our data support the hypothesis that NO is a pathogenic factor in MS, and that NOS IR is strongly expressed in brain regions appearing normal by MRI...

  1. Enzymatic oxidations of alcohols in biosynthesis of bumblebee pheromones

    OpenAIRE

    Bártová, Adéla

    2016-01-01

    Secretion of cephalic labial gland of Buff-tailed bumblebee males (Bombus terrestris) contains a mixture of terpene alcohols, aliphatic alcohols, esters and alkanes with small amount of aldehydes potentially biosynthetized of (S)-2,3-dihydrofarnesol and geranylcitronellol (major alcoholic compounds). This secretion acts as a marking and luring pheromone during patrolling. This study is focused on oxidation of terpene alcohols using enzymes of cephalic labial gland of a bumblebee. In vitro inc...

  2. Single-molecule study of oxidative enzymatic deconstruction of cellulose.

    Science.gov (United States)

    Eibinger, Manuel; Sattelkow, Jürgen; Ganner, Thomas; Plank, Harald; Nidetzky, Bernd

    2017-10-12

    LPMO (lytic polysaccharide monooxygenase) represents a unique paradigm of cellulosic biomass degradation by an oxidative mechanism. Understanding the role of LPMO in deconstructing crystalline cellulose is fundamental to the enzyme's biological function and will help to specify the use of LPMO in biorefinery applications. Here we show with real-time atomic force microscopy that C1 and C4 oxidizing types of LPMO from Neurospora crassa (NcLPMO9F, NcLPMO9C) bind to nanocrystalline cellulose with high preference for the very same substrate surfaces that are also used by a processive cellulase (Trichoderma reesei CBH I) to move along during hydrolytic cellulose degradation. The bound LPMOs, however, are immobile during their adsorbed residence time ( ~ 1.0 min for NcLPMO9F) on cellulose. Treatment with LPMO resulted in fibrillation of crystalline cellulose and strongly ( ≥ 2-fold) enhanced the cellulase adsorption. It also increased enzyme turnover on the cellulose surface, thus boosting the hydrolytic conversion.Understanding the role of enzymes in biomass depolymerization is essential for the development of more efficient biorefineries. Here, the authors show by atomic force microscopy the real-time mechanism of cellulose deconstruction by lytic polysaccharide monooxygenases.

  3. Constraints on superoxide mediated formation of manganese oxides

    Directory of Open Access Journals (Sweden)

    Deric R. Learman

    2013-09-01

    Full Text Available Manganese (Mn oxides are among the most reactive sorbents and oxidants within the environment, where they play a central role in the cycling of nutrients, metals, and carbon. Recent discoveries have identified superoxide (O2- (both of biogenic and abiogenic origin as an effective oxidant of Mn(II leading to the formation of Mn oxides. Here we examined the conditions under which abiotically produced superoxide led to oxidative precipitation of Mn and the solid-phases produced. Oxidized Mn, as both aqueous Mn(III and Mn(III/IV oxides, was only observed in the presence of active catalase, indicating that hydrogen peroxide, a product of the reaction of O2- with Mn(II, inhibits the oxidation process presumably through the reduction of Mn(III. Citrate and pyrophosphate increased the yield of oxidized Mn but decreased the amount of Mn oxide produced via formation of Mn(III-ligand complexes. While complexing ligands played a role in stabilizing Mn(III, they did not eliminate the inhibition of net Mn(III formation by H2O2. The Mn oxides precipitated were highly disordered colloidal hexagonal birnessite, similar to those produced by biotically generated superoxide. Yet, in contrast to the large particulate Mn oxides formed by biogenic superoxide, abiotic Mn oxides did not ripen to larger, more crystalline phases. This suggests that the deposition of crystalline Mn oxides within the environment requires a biological, or at least organic, influence. This work provides the first direct evidence that, under conditions relevant to natural waters, oxidation of Mn(II by superoxide can occur and lead to formation of Mn oxides. For organisms that oxidize Mn(II by producing superoxide, these findings may also point to other microbially mediated processes, in particular enzymatic hydrogen peroxide degradation and/or production of organic ligand metabolites, that allow for Mn oxide formation.

  4. Syntheses, structures, electrochemistry and catalytic oxidation degradation of organic dyes of two new coordination polymers derived from Cu(II) and Mn(II) and 1-(tetrazo-5-yl)-4-(triazo-1-yl)benzene

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ming; Mu, Bao; Huang, Ru-Dan, E-mail: huangrd@bit.edu.cn

    2017-02-15

    Two new coordination polymers (CPs), namely, [Cu{sub 2}(ttbz)(H{sub 2}btc){sub 2}(OH)]{sub n} (1) and [Mn(ttbz){sub 2}(H{sub 2}O){sub 2}]{sub n} (2) (Httbz =1-(tetrazo-5-yl)-4-(triazo-1-yl)benzene, H{sub 3}btc =1,3,5-benzenetricarboxylic acid), have been hydrothermally synthesized and structurally characterized. Complex 1 exhibits a (3,5,5,5)-connected 2D layer with a Schläfli symbol of (3·4{sup 2})(3·4{sup 4}0.5{sup 2}0.6{sup 3})(3{sup 2}0.4{sup 4}0.5{sup 2}0.6{sup 2})(3{sup 2}0.4{sup 4}0.5{sup 3}0.6), in which the ttbz{sup -} ligand can be described as μ{sub 5}-bridge, linking Cu(II) ions into a 2D layer and H{sub 2}btc{sup -} ions play a supporting role in complex 1. The ttbz{sup -} ligand in complex 2 represents the bridging coordination mode, connecting two Mn(II) ions to form the infinite 1D zigzag chains, respectively, which are further connected by two different types of hydrogen bonds to form a 3D supramolecular. Furthermore, catalytic oxidation activities toward organic dyes and electrochemical behaviors of the title complexes have been investigated at room temperature in aqueous solutions, indicating these complexes may be applicable to color removal in a textile wastewater stream and practical applications in areas of electrocatalytic reduction toward nitrite, respectively. - Graphical abstract: Two new coordination polymers based on different structural characteristics have been hydrothermally synthesized by the mixed ligands. The catalytic oxidation activities toward organic dyes and electrochemical behaviors of the title complexes have been investigated. - Highlights: • The organic ligand containing the tetrazolyl group and triazolyl group with some advantages has been used. • Two new coordination polymers with different structural characteristics has been discussed in detail. • Catalytic oxidation activities toward organic dyes and electrochemical behaviors of the title complexes have been investigated.

  5. Bioinspired design of a hybrid bifunctional enzymatic/organic electrocatalyst for site selective alcohol oxidation.

    Science.gov (United States)

    Lancaster, Louis; Hickey, David P; Sigman, Matthew S; Minteer, Shelley D; Wheeldon, Ian

    2018-01-11

    This work combines the thermostable alcohol dehydrogenase D (AdhD) from Pyrococcus furiosus and the organic electrocatalyst TEMPO to create a bifunctional catalyst that selectively oxidizes primary and secondary alcohols. The active sites function independently, can be switched on by changing reaction conditions, and can selectively oxidize a mixture of 1- and 2-butanol. The NAD + -dependent enzyme catalyses the secondary alcohol oxidation at a rate 3-fold faster than the primary alcohol, while the covalently attached 4-glycidyl-TEMPO oxidizes 1-butanol and has negligible activity toward 2-butanol. This hybrid catalytic approach has potential value for selective alcohol oxidations as well as other electrochemical and enzymatic multistep processes in energy conversion and chemical synthesis.

  6. Enzymatic oxidative transformation of phenols by Trametes trogii laccases.

    Science.gov (United States)

    Chakroun, Hanen; Bouaziz, Mohamed; Dhouib, Abdelhafidh; Sayadi, Sami

    2012-09-01

    The removal of toxic phenolic compounds from industrial wastewater is an important issue to be addressed. Their presence in water and soil has become a great environmental concern, and effective methods for their removal need to be addressed. The feasibility of applying laccases for the degradation of phenolic compounds has received increasing attention. In the present work, the transformation of five phenolic compounds (catechol, hydroxytyrosol, tyrosol, guaiacol and p-coumaric acid), the main constituents of a typical wastewater derived from an olive oil factory, by Trametes trogii laccases was studied at concentrations ranging between 0.2 and 1.6 mM. High-performance liquid chromatography analysis showed high degradation rates of phenolic compounds by T trogii laccases. Independently of the used concentration, a complete transformation of guaiacol, p-coumaric acid, hydroxytyrosol and tyrosol occurred after 1 h of incubation. The transformation of catechol depends on its initial concentration. The liquid chromatography-mass spectrometry analysis showed that laccases catalysed transformation of p-coumaric acid and tyrosol, resulting in the formation of phenolic dimers. No reduction of enzyme activity has been observed during the oxidation of all phenolic compounds. These results suggest that the studied laccases were capable of efficiently removing phenolic compounds, as well as catalysing the production of novel phenolic dimers.

  7. Blood parameters and enzymatic and oxidative activity in the liver of chickens fed with calcium anacardate

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Braga Cruz

    Full Text Available ABSTRACT The aim of this research was to evaluate the inclusion of calcium anacardate (CAC as a source of anacardic acid in the diet of broiler chickens on blood parameters, and enzymatic and oxidative activity in the liver. A total of 840 male chicks, one day old, were kept in a completely randomised experimental design, with six treatments and seven replications of 20 birds, totalling 140 birds per treatment. The treatments consisted of feed without the addition of growth promoter (GP, feed with GP, and feed with no GP and the addition of CAC at levels of 0.25, 0.50, 0.75 and 1%. The biochemical blood variables to be analysed were uric acid, total cholesterol, HDL, LDL, creatinine, AST, ALT, triglycerides, total erythrocytes, haemoglobin, haematocrit, mean corpuscular volume, corpuscular haemoglobin concentration, total plasma protein, total leukocytes, heterophils, lymphocytes, platelets and heterophil/lymphocyte ratio. The concentrations of superoxide dismutase, glutathione peroxidase and malondialdehyde were analysed for the enzymatic and oxidative parameters in the liver. There were no significant differences between treatments in the blood parameters or the enzymatic and oxidative activity in the liver of the chickens, demonstrating that the use of calcium anacardate as a source of anacardic acid is non-toxic, and does not affect these parameters.

  8. Enzymatic lipid oxidation by eosinophils propagates coagulation, hemostasis, and thrombotic disease

    Science.gov (United States)

    Uderhardt, Stefan; Ackermann, Jochen A.; Fillep, Tobias; Hammond, Victoria J.; Willeit, Johann; Stark, Konstantin; Rossaint, Jan; Schubert, Irene; Mielenz, Dirk; Dietel, Barbara; Raaz-Schrauder, Dorette; Ay, Cihan; Thaler, Johannes; Heim, Christian; Collins, Peter W.; Schabbauer, Gernot; Mackman, Nigel; Voehringer, David; Nadler, Jerry L.; Lee, James J.; Massberg, Steffen; Rauh, Manfred; O’Donnell, Valerie B.

    2017-01-01

    Blood coagulation is essential for physiological hemostasis but simultaneously contributes to thrombotic disease. However, molecular and cellular events controlling initiation and propagation of coagulation are still incompletely understood. In this study, we demonstrate an unexpected role of eosinophils during plasmatic coagulation, hemostasis, and thrombosis. Using a large-scale epidemiological approach, we identified eosinophil cationic protein as an independent and predictive risk factor for thrombotic events in humans. Concurrent experiments showed that eosinophils contributed to intravascular thrombosis by exhibiting a strong endogenous thrombin-generation capacity that relied on the enzymatic generation and active provision of a procoagulant phospholipid surface enriched in 12/15-lipoxygenase–derived hydroxyeicosatetraenoic acid–phosphatidylethanolamines. Our findings reveal a previously unrecognized role of eosinophils and enzymatic lipid oxidation as regulatory elements that facilitate both hemostasis and thrombosis in response to vascular injury, thus identifying promising new targets for the treatment of thrombotic disease. PMID:28566277

  9. Biochemical and Spectroscopic Observation of Mn(II) Sequestration from Bacterial Mn(II) Transport Machinery by Calprotectin.

    Science.gov (United States)

    Hadley, Rose C; Gagnon, Derek M; Brophy, Megan Brunjes; Gu, Yu; Nakashige, Toshiki G; Britt, R David; Nolan, Elizabeth M

    2018-01-10

    Human calprotectin (CP, S100A8/S100A9 oligomer) is a metal-sequestering host-defense protein that prevents bacterial acquisition of Mn(II). In this work, we investigate Mn(II) competition between CP and two solute-binding proteins that Staphylococcus aureus and Streptococcus pneumoniae, Gram-positive bacterial pathogens of significant clinical concern, use to obtain Mn(II) when infecting a host. Biochemical and electron paramagnetic resonance (EPR) spectroscopic analyses demonstrate that CP outcompetes staphylococcal MntC and streptococcal PsaA for Mn(II). This behavior requires the presence of excess Ca(II) ions, which enhance the Mn(II) affinity of CP. This report presents new spectroscopic evaluation of two Mn(II) proteins important for bacterial pathogenesis, direct observation of Mn(II) sequestration from bacterial Mn(II) acquisition proteins by CP, and molecular insight into the extracellular battle for metal nutrients that occurs during infection.

  10. Investigation of lipid oxidation and non-enzymatic browning reactions in marine PL emulsions

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline P.

    Marine phospholipids (PL) have received much attention recently due to their numerous advantages. One of these advantages is their better resistance towards oxidation as compared to fish oil. In addition to the antioxidative properties of α-tocopherol and phospholipids, the better oxidative...... stability of marine PL might be attributed to antioxidative properties of pyrroles formed between oxidised lipids with amine groups from phosphatidylethanolamine (PE) or residues amino acids that are present in marine PL. The main objective of this study was to investigate if the presence of amine group...... from PE or amino acids affected the oxidative stability of purified marine PL emulsions. The secondary objective was to study the non-enzymatic browning reactions in the emulsions which included both Strecker degradation (SD) and pyrroles formation. Emulsions were prepared with and without addition...

  11. Kinetics of reaction between O 2 and Mn(II) species in aqueous solutions

    Science.gov (United States)

    Morgan, James J.

    2005-01-01

    The objective of this research is to assess critically the experimental rate data for O 2 oxidation of dissolved Mn(II) species at 25°C and to interpret the rates in terms of the solution species of Mn(II) in natural waters. A species kinetic rate expression for parallel paths expresses the total rate of Mn(II) oxidation as Σk i a ij, where k i is the rate constant of species i and a ij is the species concentration fraction in solution j. Among the species considered in the rate expression are Mn(II) hydrolysis products, carbonate complexes, ammonia complexes, and halide and sulfate complexes, in addition to the free aqueous ion. Experiments in three different laboratory buffers and in seawater yield an apparent rate constant for Mn(II) disappearance, k app,j ranging from 8.6 × 10 -5 to 2.5 × 10 -2 (M -1s -1), between pH 8.03 and 9.30, respectively. Observed values of k app exceed predictions based on Marcus outer-sphere electron transfer theory by more than four orders of magnitude, lending strong support to the proposal that Mn(II) + O 2 electron transfer follows an inner-sphere path. A multiple linear regression analysis fit of the observed rates to the species kinetic rate expression yields the following oxidation rate constants (M -1s -1) for the most reactive species: MnOH +, 1.66 × 10 -2; Mn(OH) 2, 2.09 × 10 1; and Mn(CO 3) 22-, 8.13 × 10 -2. The species kinetic rate expression accounts for the influence of pH and carbonate on oxidation rates of Mn(II), through complex formation and acid-base equilibria of both reactive and unreactive species. At pH ˜8, the greater fraction of the total rate is carried by MnOH +. At pH greater than ˜8.4, the species Mn(OH) 2 and Mn(CO 3) 22- make the greater contributions to the total rate.

  12. "Aerogels of enzymatically oxidized galactomannans from leguminous plants: Versatile delivery systems of antimicrobial peptides and enzymes".

    Science.gov (United States)

    Campia, Paola; Ponzini, Erika; Rossi, Bianca; Farris, Stefano; Silvetti, Tiziana; Merlini, Luca; Brasca, Milena; Grandori, Rita; Galante, Yves M

    2017-02-20

    We describe aerogels obtained by laccase/TEMPO-oxidation and lyophilization of galactomannans (GM) from fenugreek, sesbania and guar. Enzymatic oxidation of GM in aqueous solution caused viscosity increase up to fifteen-fold, generating structured, elastic, stable hydrogels, presumably due to establishment of hemiacetalic bonds between newly formed carbonyl groups and free hydroxyl groups. Upon lyophilization, water-insoluble aerogels were obtained, whose mechanical properties and porosity were investigated. Active principles were absorbed into the aerogels from aqueous solutions and, following rinsing, blotting, re-lyophilization, were released in an appropriate medium. The release of the antibiotic polymyxin B was tested against six different Gram-negative bacterial strains, of the antimicrobial peptide nisin against two Gram-positive and of the muraminidase lysozyme against one anaerobic strain. Protease and lipase release in solution from "enzyme loaded" aerogels was monitored by the increase in enzymatic activity. These biomaterials could represent new versatile, biocompatible "delivery systems" of actives for biomedical and industrial applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Oxidant and enzymatic antioxidant status (gene expression and activity) in the brain of chickens with cold-induced pulmonary hypertension

    Science.gov (United States)

    Hassanpour, Hossein; Khalaji-Pirbalouty, Valiallah; Nasiri, Leila; Mohebbi, Abdonnaser; Bahadoran, Shahab

    2015-11-01

    To evaluate oxidant and antioxidant status of the brain (hindbrain, midbrain, and forebrain) in chickens with cold-induced pulmonary hypertension, the measurements of lipid peroxidation, protein oxidation, antioxidant capacity, enzymatic activity, and gene expression (for catalase, glutathione peroxidase, and superoxide dismutases) were done. There were high lipid peroxidation/protein oxidation and low antioxidant capacity in the hindbrain of cold-induced pulmonary hypertensive chickens compared to control ( P pulmonary hypertension.

  14. Enzymatic Browning in Sugar Beet Leaves (Beta vulgaris L.): Influence of Caffeic Acid Derivatives, Oxidative Coupling, and Coupled Oxidation.

    Science.gov (United States)

    Vissers, Anne; Kiskini, Alexandra; Hilgers, Roelant; Marinea, Marina; Wierenga, Peter Alexander; Gruppen, Harry; Vincken, Jean-Paul

    2017-06-21

    Sugar beet (Beta vulgaris L.) leaves of 8 month (8 m ) plants showed more enzymatic browning than those of 3 month (3 m ). Total phenolic content increased from 4.6 to 9.4 mg/g FW in 3 m and 8 m , respectively, quantitated by reverse-phase-ultrahigh-performance liquid chromatography-ultraviolet-mass spectrometry (RP-UHPLC-UV-MS). The PPO activity was 6.7 times higher in extracts from 8 m than from 3 m leaves. Substrate content increased from 0.53 to 2.45 mg/g FW in 3 m and 8 m , respectively, of which caffeic acid glycosyl esters were most important, increasing 10-fold with age. Caffeic acid glycosides and vitexin derivatives were no substrates. In 3 m and 8 m, nonsubstrate-to-substrate ratios were 8:1 and 3:1, respectively. A model system showed browning at 3:1 ratio due to formation of products with extensive conjugated systems through oxidative coupling and coupled oxidation. The 8:1 ratio did not turn brown as oxidative coupling occurred without much coupled oxidation. We postulate that differences in nonsubstrate-to-substrate ratio and therewith extent of coupled oxidation explain browning.

  15. Non-Enzymatic Glucose Sensor Composed of Carbon-Coated Nano-Zinc Oxide

    Directory of Open Access Journals (Sweden)

    Ren-Jei Chung

    2017-02-01

    Full Text Available Nowadays glucose detection is of great importance in the fields of biological, environmental, and clinical analyzes. In this research, we report a zinc oxide (ZnO nanorod powder surface-coated with carbon material for non-enzymatic glucose sensor applications through a hydrothermal process and chemical vapor deposition method. A series of tests, including crystallinity analysis, microstructure observation, and electrochemical property investigations were carried out. For the cyclic voltammetric (CV glucose detection, the low detection limit of 1 mM with a linear range from 0.1 mM to 10 mM was attained. The sensitivity was 2.97 μA/cm2mM, which is the most optimized ever reported. With such good analytical performance from a simple process, it is believed that the nanocomposites composed of ZnO nanorod powder surface-coated with carbon material are promising for the development of cost-effective non-enzymatic electrochemical glucose biosensors with high sensitivity.

  16. Degradation of phenols in olive oil mill wastewater by biological, enzymatic, and photo-Fenton oxidation.

    Science.gov (United States)

    Justino, Celine; Marques, Ana Gabriela; Duarte, Kátia Reis; Duarte, Armando Costa; Pereira, Ruth; Rocha-Santos, Teresa; Freitas, Ana Cristina

    2010-03-01

    Olive oil mill wastewater (OOMW) environmental impacts minimization have been attempted by developing more effective processes, but no chemical or biological treatments were found to be totally effective to mitigate their impact on receiving systems. This work is the first that reports simultaneously the efficiency of three different approaches: biological treatment by two fungal species (Trametes versicolor or Pleurotus sajor caju), enzymatic treatment by laccase, and chemical treatment by photo-Fenton oxidation on phenols removal. Those treatments were performed on OOMW with or without phenol supplement (p-coumaric, vanillin, guaiacol, vanillic acid, or tyrosol). OOMW samples resulted from treatments were extracted for phenols using liquid-liquid extraction and analyzed by gas chromatography coupled to mass spectrometry. Treatment with T. versicolor or P. sajor caju were able to remove between 22% and 74% and between 8% and 76% of phenols, respectively. Treatment by laccase was able to reduce 4% to 70% of phenols whereas treatment by photo-Fenton oxidation was responsible for 100% phenols reduction. Range of phenol degradation was equivalent between T. versicolor, P. sajor caju and laccase for p-coumaric, guaiacol, caffeic acid, and tyrosol in supplemented OOMW, which enhances this enzyme role in the biological treatment promoted by these two species. Phenols were removed more efficiently by photo-Fenton treatment than by biological or enzymatic treatments. Use of fungi, laccase, or photo-Fenton presents great potential for removing phenols from OOMW. This should be further assessed by increasing the application scale and the reactor configurations effect on the performance, besides a toxicity evaluation of treated wastewater in comparison to raw wastewater.

  17. Evaluation of peroxidases from roots of Cyperus hermaphroditus as enzymatic mechanisms in phenanthrene oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero Zuniga, A. [Inst. Mexicano del Petroleo, Mexico City (Mexico). Environmental Protection Management Office; Rodriguez Dorantes, A.M. [Lab. Fisiologia Vegetal, Escuela Nacional de Ciencias Biologicas, Mexico City (Mexico). Depto Botanica

    2006-07-01

    Although phenanthrene is not mutagenic or carcinogenic, it has been shown to be toxic to aquatic organisms. This study evaluated in-vitro phenanthrene oxidation by peroxidases from radical extracts of Cyperus hermaphroditus plants. The characterization of oxidation products of phenanthrene related to the induction of root peroxidases was also examined. Concentrated ethanol stock of phenanthrene solution was added to the mineral solution of each plant container. The total radical biomass was placed in 4.5 ml of an ionic solution to analyze the enzymatic activity of the extracellular peroxidases. The total protein for each experiment was quantified by the Bradford method. Extracellular peroxidases activity was measured using the spectrophotometric method. The amount of radical biomass was quantified as high in the 80 and 120 ppm phenanthrene treatments relative to the control plants. It was suggested that the nature of the Cyperaceae roots combined with the high-octanol water coefficient and a low water solubility for phenanthrene may have facilitated the stabilization of the contaminant towards the roots. The ability of Cyperus hermaphroditus to immobilize phenanthrene through its adhesion was encouraged by the conditions of the hydroponic culture system. The adsorption of phenanthrene was increased with the time of exposure to the contaminant due to the greater total root mass. The study also showed the transformation of phenanthrene by radical extracts of Cyperus hermaphroditus containing guaiacol peroxidases with 12 per cent residual phenanthrene in the in vitro assays. The spectrophotometric analysis confirmed that the enzymatic systems are responsible for the phytotransformation of the pollutant. 9 refs., 2 tabs., 5 figs.

  18. High selective delignification using oxidative ionic liquid pretreatment at mild conditions for efficient enzymatic hydrolysis of lignocellulose.

    Science.gov (United States)

    Pang, Zhiqiang; Lyu, Wenkang; Dong, Cuihua; Li, Hongxing; Yang, Guihua

    2016-08-01

    Herein, the oxidative ionic liquid (IL) pretreatment for overcoming recalcitrance of lignocellulose with selective delignification was investigated, and the subsequent enzymatic hydrolysis was evaluated. IL pretreatment incorporating oxygen delignification could enhance lignin extraction with high selectivity at low carbohydrate loss. The dual-action of oxidative decomposition and dissolution by 1-butyl-3-methlimidazolium chloride (BmimCl) on biomass were synergistically acted, accounting for efficient recalcitrance removal. In addition, the mild oxidative IL treatment only slightly converted crystalline cellulose into amorphous structure, and the extensive extraction of the amorphous lignin and carbohydrate resulted to the expose of cellulose with high susceptibility. Correspondingly, the enzymatic hydrolysis of the pretreated lignocellulose was greatly enhanced. The oxidative IL treatment at mild conditions, collaborating BmimCl treatment with oxygen delignification is a promising and effective system for overcoming the robust structure of lignocellulose. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Processing surface sizing starch using oxidation, enzymatic hydrolysis and ultrasonic treatment methods--Preparation and application.

    Science.gov (United States)

    Brenner, Tobias; Kiessler, Birgit; Radosta, Sylvia; Arndt, Tiemo

    2016-03-15

    The surface application of starch is a well-established method for increasing paper strength. In surface sizing, a solution of degraded starch is applied to the paper. Two procedures have proved valuable for starch degradation in the paper mill: enzymatic and thermo-oxidative degradation. The objective of this study was to determine achievable efficiencies of cavitation in preparing degraded starch for surface application on paper. It was found that ultrasonic-assisted starch degradation can provide a starch solution that is suitable for surface sizing. The molecular composition of starch solutions prepared by ultrasonic treatment differed from that of starch solutions degraded by enzymes or by thermo-oxidation. Compared to commercial degradation processes, this resulted in intensified film formation and in greater penetration during surface sizing and ultimately in a higher starch content of the paper. Paper sized with ultrasonically treated starch solutions show the same strength properties compared to commercially sized paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Non-Enzymatic Glucose Sensing Using Carbon Quantum Dots Decorated with Copper Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Houcem Maaoui

    2016-10-01

    Full Text Available Perturbations in glucose homeostasis is critical for human health, as hyperglycemia (defining diabetes leads to premature death caused by macrovascular and microvascular complications. However, the simple and accurate detection of glucose in the blood at low cost remains a challenging task, although it is of great importance for the diagnosis and therapy of diabetic patients. In this work, carbon quantum dots decorated with copper oxide nanostructures (CQDs/Cu2O are prepared by a simple hydrothermal approach, and their potential for electrochemical non-enzymatic glucose sensing is evaluated. The proposed sensor exhibits excellent electrocatalytic activity towards glucose oxidation in alkaline solutions. The glucose sensor is characterized by a wide concentration range from 6 µM to 6 mM, a sensitivity of 2.9 ± 0.2 µA·µM−1·cm−2, and a detection limit of 6 µM at a signal-to-noise ratio S/N = 3. The sensors are successfully applied for glucose determination in human serum samples, demonstrating that the CQDs/Cu2O-based glucose sensor satisfies the requirements of complex sample detection with adapted potential for therapeutic diagnostics.

  1. Networks of enzymatically oxidized membrane lipids support calcium-dependent coagulation factor binding to maintain hemostasis.

    Science.gov (United States)

    Lauder, Sarah N; Allen-Redpath, Keith; Slatter, David A; Aldrovandi, Maceler; O'Connor, Anne; Farewell, Daniel; Percy, Charles L; Molhoek, Jessica E; Rannikko, Sirpa; Tyrrell, Victoria J; Ferla, Salvatore; Milne, Ginger L; Poole, Alastair W; Thomas, Christopher P; Obaji, Samya; Taylor, Philip R; Jones, Simon A; de Groot, Phillip G; Urbanus, Rolf T; Hörkkö, Sohvi; Uderhardt, Stefan; Ackermann, Jochen; Vince Jenkins, P; Brancale, Andrea; Krönke, Gerhard; Collins, Peter W; O'Donnell, Valerie B

    2017-11-28

    Blood coagulation functions as part of the innate immune system by preventing bacterial invasion, and it is critical to stopping blood loss (hemostasis). Coagulation involves the external membrane surface of activated platelets and leukocytes. Using lipidomic, genetic, biochemical, and mathematical modeling approaches, we found that enzymatically oxidized phospholipids (eoxPLs) generated by the activity of leukocyte or platelet lipoxygenases (LOXs) were required for normal hemostasis and promoted coagulation factor activities in a Ca 2+ - and phosphatidylserine (PS)-dependent manner. In wild-type mice, hydroxyeicosatetraenoic acid-phospholipids (HETE-PLs) enhanced coagulation and restored normal hemostasis in clotting-deficient animals genetically lacking p12-LOX or 12/15-LOX activity. Murine platelets generated 22 eoxPL species, all of which were missing in the absence of p12-LOX. Humans with the thrombotic disorder antiphospholipid syndrome (APS) had statistically significantly increased HETE-PLs in platelets and leukocytes, as well as greater HETE-PL immunoreactivity, than healthy controls. HETE-PLs enhanced membrane binding of the serum protein β2GP1 (β2-glycoprotein 1), an event considered central to the autoimmune reactivity responsible for APS symptoms. Correlation network analysis of 47 platelet eoxPL species in platelets from APS and control subjects identified their enzymatic origin and revealed a complex network of regulation, with the abundance of 31 p12-LOX-derived eoxPL molecules substantially increased in APS. In summary, circulating blood cells generate networks of eoxPL molecules, including HETE-PLs, which change membrane properties to enhance blood coagulation and contribute to the excessive clotting and immunoreactivity of patients with APS. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  2. Improvement of enzymatic hydrolysis and ethanol production from corn stalk by alkali and N-methylmorpholine-N-oxide pretreatments.

    Science.gov (United States)

    Cai, Ling-Yan; Ma, Yu-Long; Ma, Xiao-Xia; Lv, Jun-Min

    2016-07-01

    A combinative technology of alkali and N-methylmorpholine-N-oxide (NMMO) was used to pretreat corn stalk (CS) for improving the efficiencies of subsequent enzymatic hydrolysis and ethanol fermentation. The results showed that this strategy could not only remove hemicellulose and lignin but also decrease the crystallinity of cellulose. About 98.0% of enzymatic hydrolysis yield was obtained from the pretreated CS as compared with 46.9% from the untreated sample. The yield for corresponding ethanol yield was 64.6% while untreated CS was only 18.8%. Besides, xylose yield obtained from the untreated CS was only 11.1%, while this value was 93.8% for alkali with NMMO pretreated sample. These results suggest that a combination of alkali with 50% (wt/wt) NMMO solution may be a promising alternative for pretreatment of lignocellulose, which can increase the productions of subsequent enzymatic hydrolysis and ethanol fermentation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Enhanced enzymatic hydrolysis and acetone-butanol-ethanol fermentation of sugarcane bagasse by combined diluted acid with oxidate ammonolysis pretreatment.

    Science.gov (United States)

    Li, Hailong; Xiong, Lian; Chen, Xuefang; Wang, Can; Qi, Gaoxiang; Huang, Chao; Luo, Mutan; Chen, Xinde

    2017-03-01

    This study aims to propose a biorefinery pretreatment technology for the bioconversion of sugarcane bagasse (SB) into biofuels and N-fertilizers. Performance of diluted acid (DA), aqueous ammonia (AA), oxidate ammonolysis (OA) and the combined DA with AA or OA were compared in SB pretreatment by enzymatic hydrolysis, structural characterization and acetone-butanol-ethanol (ABE) fermentation. Results indicated that DA-OA pretreatment improves the digestibility of SB by sufficiently hydrolyzing hemicellulose into fermentable monosaccharides and oxidating lignin into soluble N-fertilizer with high nitrogen content (11.25%) and low C/N ratio (3.39). The enzymatic hydrolysates from DA-OA pretreated SB mainly composed of glucose was more suitable for the production of ABE solvents than the enzymatic hydrolysates from OA pretreated SB containing high ratio of xylose. The fermentation of enzymatic hydrolysates from DA-OA pretreated SB produced 12.12g/L ABE in 120h. These results suggested that SB could be utilized efficient, economic, and environmental by DA-OA pretreatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Optimization of a Liquid Crystal-based Sensory Platform for Monitoring Enzymatic Glucose Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Yibin; Jang, Chang-Hyun [Gachon University, Seongnam (Korea, Republic of)

    2016-05-15

    Managing glucose levels in human blood is extremely important for the treatment of diabetes. Here, an innovative sensory strategy has been developed to monitor the enzymatic activities of glucose and glucose oxidase by using confined liquid crystal (LC) birefringent droplet patterns. Acidic products released during the glucose oxidation process lead to a slight decrease in the pH of aqueous systems that can be monitored by pH-sensitive LC materials. Of the existing pH-sensitive LC materials, dodecanoic acid-doped 4-cyano-4'-pentylbiphenyl is inexpensive and easily adjusted to satisfy the 7.4 ± 0.05 pH requirement of human blood. Moreover, the orientational alignment of capillary-confined pH-responsive LCs can be disrupted at the aqueous/LC interface following a slight decrease in the critical pH of aqueous reaction systems, which results in an optical signal that can be observed with the naked eye by using polarizing optical microscopy. Based on the stable LC droplet patterns generated by the cylindrical confinement system, the functionalized LCs can selectively detect glucose at concentrations as low as 0.1 pM. This study further advances the previously reported LC-based glucose monitoring systems by reducing production costs and instituting a smarter LC sensory design. This improved system shows potential for the use in clinical bioassay applications.

  5. Vertically grown zinc oxide nanorods functionalized with ferric oxide for in vivo and non-enzymatic glucose detection

    Science.gov (United States)

    Marie, Mohammed; Manoharan, Anishkumar; Kuchuk, Andrian; Ang, Simon; Manasreh, M. O.

    2018-03-01

    An enzyme-free glucose sensor based on vertically grown zinc oxide nanorods (NRs) functionalized with ferric oxide (Fe2O3) is investigated. The well-aligned and high density ZnO NRs were synthesized on an FTO/glass substrate by a sol-gel and hydrothermal growth method. A dip-coating technique was utilized to modify the surface of the as-grown ZnO NRs with Fe2O3. The immobilized surface was coated with a layer of nafion membrane. The fabricated glucose sensor was characterized amperometrically at room temperature using three electrodes stationed in the phosphate buffer solution, where ZnO NRs/Fe2O3/nafion membrane was the sensing or working electrode, and platinum plate and silver/silver chloride were used as the counter and reference electrodes, respectively. The proposed non-enzymatic and modified glucose sensor exhibited a high sensitivity in the order of 0.052 μA cm-2 (mg/dL)-1, a lower detection limit of around 0.95 mmol L-1, a sharp and fast response time of ˜1 s, and a linear response to changes in glucose concentrations from 100-400 mg dL-1. The linear amperometric response of the sensor covers the physiological and clinical interest of glucose levels for diabetic patients. The device continues to function accurately after multiple measurements with a good reproducibility. The proposed glucose sensor is expected to be used clinically for in vivo monitoring of glucose.

  6. Multireversible redox processes in pentanuclear bis(triple-helical) manganese complexes featuring an oxo-centered triangular {Mn(II)2Mn(III)(μ3-O)}5+ or {Mn(II)Mn(III)2(μ3-O)}6+ core wrapped by two {Mn(II)2(bpp)3}-.

    Science.gov (United States)

    Romain, Sophie; Rich, Jordi; Sens, Cristina; Stoll, Thibaut; Benet-Buchholz, Jordi; Llobet, Antoni; Rodriguez, Montserrat; Romero, Isabel; Clérac, Rodolphe; Mathonière, Corine; Duboc, Carole; Deronzier, Alain; Collomb, Marie-Noëlle

    2011-09-05

    A new pentanuclear bis(triple-helical) manganese complex has been isolated and characterized by X-ray diffraction in two oxidation states: [{Mn(II)(μ-bpp)(3)}(2)Mn(II)(2)Mn(III)(μ-O)](3+) (1(3+)) and [{Mn(II)(μ-bpp)(3)}(2)Mn(II)Mn(III)(2)(μ-O)](4+) (1(4+)). The structure consists of a central {Mn(3)(μ(3)-O)} core of Mn(II)(2)Mn(III) (1(3+)) or Mn(II)Mn(III)(2) ions (1(4+)) which is connected to two apical Mn(II) ions through six bpp(-) ligands. Both cations have a triple-stranded helicate configuration, and a pair of enantiomers is present in each crystal. The redox properties of 1(3+) have been investigated in CH(3)CN. A series of five distinct and reversible one-electron waves is observed in the -1.0 and +1.50 V potential range, assigned to the Mn(II)(4)Mn(III)/Mn(II)(5), Mn(II)(3)Mn(III)(2)/Mn(II)(4)Mn(III), Mn(II)(2)Mn(III)(3)/Mn(II)(3)Mn(III)(2), Mn(II)Mn(III)(4)/Mn(II)(2)Mn(III)(3), and Mn(III)(5)/Mn(II)Mn(III)(4) redox couples. The two first oxidation processes leading to Mn(II)(3)Mn(III)(2) (1(4+)) and Mn(II)(2)Mn(III)(3) (1(5+)) are related to the oxidation of the Mn(II) ions of the central core and the two higher oxidation waves, close in potential, are thus assigned to the oxidation of the two apical Mn(II) ions. The 1(4+) and 1(5+) oxidized species and the reduced Mn(4)(II) (1(2+)) species are quantitatively generated by bulk electrolyses demonstrating the high stability of the pentanuclear structure in four oxidation states (1(2+) to 1(5+)). The spectroscopic characteristics (X-band electron paramagnetic resonance, EPR, and UV-visible) of these species are also described as well as the magnetic properties of 1(3+) and 1(4+) in solid state. The powder X- and Q-band EPR signature of 1(3+) corresponds to an S = 5/2 spin state characterized by a small zero-field splitting parameter (|D| = 0.071 cm(-1)) attributed to the two apical Mn(II) ions. At 40 K, the magnetic behavior is consistent for 1(3+) with two apical S = 5/2 {Mn(II)(bpp)(3)}(-) and one S

  7. Novel synthesis and structural analysis of zinc oxide nanoparticles for the non enzymatic glucose biosensor.

    Science.gov (United States)

    Dayakar, T; Venkateswara Rao, K; Bikshalu, K; Rajendar, V; Park, Si-Hyun

    2017-06-01

    A non-enzymatic glucose biosensor was developed by utilizing the zinc oxide nanoparticles (ZnO NPs) synthesized by a novel green method using the leaf extract of Ocimum tenuiflorum. The structural, optical and morphological properties of ZnO NPs characterized by means of X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDAX) spectroscopy, and transmission electron microscopy (TEM). The XRD analysis revealed that the ZnO NPs were crystalline and had a hexagonal wurtzite structure. The crystallite size measured by XRD was the same as that measured using SEM and TEM. The UV-vis absorption spectrum estimates the band gap of ZnO NPs present in the range of 2.82 to 3.45eV. The reduction and formation of ZnO NPs mainly due to the involvement of leaf extract bio-molecular compounds analyzed from the FTIR spectra. The SEM result confirms the morphology of the NPs responsible from the various concentration of leaf extract in the synthesis process. HRTEM analysis depicts the spherical structure of ZnO NPs. The synthesized NPs have the average size ranges from 10 to 20nm. The fabricated GCE/ZnO glucose sensor represents superior electro catalytic activity that has been observed for ZnO NPs with a reproducible sensitivity of 631.30μAmM -1 cm -2 , correlation coefficient of R=0.998, linear dynamic range from 1-8.6mM, low detection limit of 0.043μM (S/N=3) and response time<4s. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Topotactic reduction as a synthetic route for the preparation of low-dimensional Mn(II) oxide phases: the structure and magnetism of LaAMnO(4-x) (A = Sr, Ba).

    Science.gov (United States)

    Kitchen, Helen J; Saratovsky, Ian; Hayward, Michael A

    2010-07-14

    Reaction of LaSrMnO(4) with CaH(2) at 420 degrees C yields LaSrMnO(3.67(3)). Raising the temperature to 480 degrees C yields the Mn(II) phase LaSrMnO(3.50(2)). Neutron powder diffraction data show both phases adopt body-centred orthorhombic crystal structures (LaSrMnO(3.67(3)), Immm: a = 3.7256(1) A, b = 3.8227(1) A, c = 13.3617(4) A; LaSrMnO(3.50(2)), Immm: a = 3.7810(1) A, b = 3.7936(1) A, c = 13.3974(3) A) with anion vacancies located within the equatorial MnO(2-x) planes of the materials. Analogous reactivity is observed between LaBaMnO(4) and CaH(2) to yield body-centred tetragonal reduced phases (LaBaMnO(3.53(3)), I4/mmm: a = 3.8872(1)A, c = 13.6438(2) A). Low-temperature neutron diffraction and magnetisation data show that LaSrMnO(3.5) and LaBaMnO(3.5) exhibit three-dimensional antiferromagnetic order below 155 K and 135 K respectively. Above these temperatures, they exhibit two-dimensional antiferromagnetic order with paramagnetic behaviour observed above 480 K in both phases. The origin of the low dimensional magnetic order and ordering of the anion vacancies in the reduced phases is discussed.

  9. Wet oxidation pre-treatment of woody yard waste: Parameter optimization and enzymatic digestibility for ethanol production

    DEFF Research Database (Denmark)

    Lissens, G.; Klinke, H.B.; Verstraete, W.

    2004-01-01

    Woody yard waste with high lignin content (22% of dry matter (DM)) was subjected to wet oxidation pre-treatment for subsequent enzymatic conversion and fermentation. The effects of temperature (185-200 degreesC), oxygen pressure (3-12 bar) and addition of sodium carbonate (0-3.3 g per 100 g DM...... biomass) on enzymatic cellulose and hemicellulose (xylan) convertibility were studied. The enzymatic cellulose conversion was highest after wet oxidation for 15 min at 185 degreesC with addition of 12 bars of oxygen and 3.3 g Na2CO3 per 100g waste. At 25 FPU (filter paper unit) cellulase g(-1) DM added......, 58-67% and 80-83% of the cellulose and hemicellulose contained in the waste were converted into monomeric sugars. The cellulose conversion efficiency during a simultaneous saccharification and fermentation (SSF) assay at 10% DM was 79% for the highest enzyme loading (25 FPU g(-1) DM) while 69...

  10. Mn(II) complexes with bipyridine, phenanthroline and benzoic acid ...

    Indian Academy of Sciences (India)

    ... complexes and the antifungal (anticandidal) activities of the Mn(II) complexes were remarkably higher than the reference drug ketoconazole. Keywords. Manganese complex; catalase; biological activity; hydrogen peroxide; bipyridine; phenanthroline. 1. Introduction. The synthesis of transition metal complexes that exhibit.

  11. Schiff base ligand derived from (±trans-1,2-cyclohexanediamine and its Cu(II, Co(II, Zn(II and Mn(II complexes: Synthesis, characterization, styrene oxidation and hydrolysis study of the imine bond in Cu(II Schiff base complex

    Directory of Open Access Journals (Sweden)

    Sarkheil Marzieh

    2016-01-01

    Full Text Available A Schiff base ligand (H2L derived from 2´-hydroxypropiophenone and (±trans-1,2-cyclohexanediamine was synthesized. The reactions of MCl2.xH2O (M =Cu(II, Co(II, Zn(II and Mn(IIwith the di-Schiff base ligand (H2L were studied. This ligand when stirred with 1 equivalent of CuCl2.2H2O in the solution of ethanol and chloroform undergoes partial hydrolysis of the imino bond and the resultant tridentate ligand (HL′immediately forms complex[CuL´Cl]∙3/2CHCl3(1with N2O coordination sphere. Under the same condition, the reaction of H2L with MCl2.xH2O (M = Co(II (3, Zn(II (4 and Mn(II (5 gave complexes[ML]•1/2CHCl3∙3/2H2O (3-5with N2O2 coordination sphere and no hydrolytic cleavage was occurred. Also, the reaction of H2L with CuCl2.2H2O in THF gave the complex CuL (2with N2O2 coordination sphere. The ligand and complexes were characterized by FTIR, UV-Vis, 1H NMRand elemental analysis. The homogeneous catalytic activity of the complexes1, 3 and 5wasevaluated for the oxidation of styrene using tert-butyl hydroperoxide (TBHP as oxidant. Finally, the copper(II complex(1encapsulated in the nanopores of zeolite-Y by flexible ligand method (CuL´-Yand its encapsulation was ensured by different studies. The catalytic performance of heterogeneous catalyst in the styrene oxidation with TBHP was investigated. The catalytic tests showed that the homogenous and heterogeneous catalysts were active in the oxidation of styrene.

  12. Effect of Cadmium Stress on Non-enzymatic Antioxidant and Nitric Oxide Levels in Two Varieties of Maize (Zea mays).

    Science.gov (United States)

    Akinyemi, Ayodele Jacob; Faboya, Oluwabamise Lekan; Olayide, Israel; Faboya, Opeyemi Ayodeji; Ijabadeniyi, Tosin

    2017-06-01

    Cadmium (Cd) is one of the most toxic heavy metals that inhibit physiological processes of plants. Hence, the present study sought to investigate the effect of cadmium-contaminated seeds from two varieties of maize (Zea mays) on non-enzymatic antioxidant and nitric oxide levels. Seeds of yellow and white maize were exposed to different concentrations of Cd (0, 1, 3 and 5 ppm) for two weeks. The results from this study revealed that both varieties of maize bio-accumulate Cd in leaves in a dose-dependent manner. In addition, Cd exposure caused a significant (p < 0.05) decrease in total phenolic, GSH and nitric oxide (NO) levels at the highest concentration tested when compared with control. Therefore, the observed decrease in NO and endogenous antioxidant status by Cd treatment in maize plants could suggest some possible mechanism of action for Cd-induced oxidative stress and counteracting effect of the plants against Cd toxicity.

  13. Enzymatic halogenation and oxidation using an alcohol oxidase-vanadium chloroperoxidase cascade

    NARCIS (Netherlands)

    But, Andrada; Noord, Van Aster; Poletto, Francesca; Sanders, Johan P.M.; Franssen, Maurice C.R.; Scott, Elinor L.

    2017-01-01

    The chemo-enzymatic cascade which combines alcohol oxidase from Hansenula polymorpha (AOXHp) with vanadium chloroperoxidase (VCPO), for the production of biobased nitriles from amino acids was investigated. In the first reaction H2O2 (and acetaldehyde) are generated from ethanol and oxygen by AOXHp.

  14. Anticancer system created by acrolein and hydroxyl radical generated in enzymatic oxidation of spermine and other biochemical reactions.

    Science.gov (United States)

    Alarcon, R A

    2012-10-01

    A hypothesis suggesting the existence of a ubiquitous physiological anticancer system created by two highly reactive oxidative stress inducers with anticancer properties, acrolein and hydroxyl radical, is reported in this communication. Both components can originate separately or together in several biochemical interactions, among them, the enzymatic oxidation of the polyamine spermine, which appear to be their main source. The foundations of this hypothesis encompass our initial search for growth-inhibitors or anticancer compounds in biological material leading to the isolation of spermine, a polyamine that became highly cytotoxic through the generation of acrolein, when enzymatically oxidized. Findings complemented with pertinent literature data by other workers and observed anticancer activities by sources capable of producing acrolein and hydroxyl radical. This hypothesis obvious implication: spermine enzymatic oxidations or other biochemical interactions that would co-generate acrolein and hydroxyl radical, the anticancer system components, should be tried as treatments for any given cancer. The biochemical generation of acrolein observed was totally unexpected, since this aldehyde was known; as a very toxic and highly reactive xenobiotic chemical produced in the pyrolysis of fats and other organic material, found as an atmospheric pollutant, in tobacco smoke and car emissions, and mainly used as a pesticide or aquatic herbicide. Numerous studies on acrolein, considered after our work a biological product, as well, followed. In them, acrolein widespread presence, its effects on diverse cellular proteins, such as, growth factors, and its anticancer activities, were additionally reported. Regarding hydroxyl radical, the second component of the proposed anticancer system, and another cytotoxic product in normal cell metabolism, it co-generates with acrolein in several biochemical interactions, occurrences suggesting that these products might jointly fulfill some

  15. Electrochemical oxidation of nucleotide cofactors. Characterisation and process development of asymmetrical enzymatic catalysis systems; Elektrochemische Oxidation von Nukleotidkofaktoren Charakterisierung und Prozessentwicklung asymmetrischer enzymatischer Katalysesysteme

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, I.

    2003-06-01

    A new electrochemical mediator for electroenzymatic syntheses with nucleotide factor dependent dehydrogenases was to be developed. The main task was the verification of the applicability of the radical cation 2,2'-azinobis-(3-ethyl benzothiazoline-6-sulfonate (ABTS)) as an electron transfer mediator for in situ oxidation of NADH and NADPH to the corresponding biologically active nucleotide factors. The radical cation ABTS was to be generated by an electrochemical process, and the mediated cofactor regeneration was to be coupled successfully with at least one enzymatic reaction.

  16. Enzymatic Baeyer-Villiger Oxidation of Benzo-Fused Ketones : Formation of Regiocomplementary Lactones

    NARCIS (Netherlands)

    Rioz-Martinez, Ana; de Gonzalo, Gonzalo; Pazmino, Daniel E. Torres; Fraaije, Marco W.; Gotor, Vicente

    Baeyer-Villiger monooxygenases (BVMOs) are enzymes that are known to catalyse the Baeyer-Villiger oxidation of ketones in aqueous media using O(2) as oxidant. Herein, we describe the oxidation of a set of diverse benzo-fused ketones by three different BVMOs in both aqueous and non-conventional

  17. Effects of Cobalt on Manganese Oxidation by Pseudomonas putida MnB1

    Science.gov (United States)

    Pena, J.; Bargar, J.; Sposito, G.

    2005-12-01

    The oxidation of Mn(II) in the environment is thought to occur predominantly through biologically mediated pathways. During the stationary phase of growth, the well-characterized freshwater and soil bacterium Pseudomonas putida MnB1 oxidizes soluble Mn(II) to a poorly crystalline layer type Mn(IV) oxide. These Mn oxide particles (2 - 5 nm thickness) are deposited in a matrix of extracellular polymeric substances (EPS) surrounding the cell, creating a multi-component system distinct from commonly studied synthetic Mn oxides. Accurate characterization of the reactivity of these biomineral assemblages is essential to understanding trace metal biogeochemistry in natural waters and sediments. Moreover, these biogenic oxides may potentially be used for the remediation of surface and ground waters impacted by mining, industrial pollution, and other anthropogenic activities. In this study, we consider the interactions between Co, P. putida MnB1, and its biogenic Mn oxide. Cobalt is a redox-active transition metal which exists in the environment as Co(II) and Co(III). While Co is not generally found in the environment at toxic concentrations, it may be released as a byproduct of mining activities (e.g. levels of up to 20 μM are found in Pinal Creek, AZ, a stream affected by copper mining). In addition, the radionuclide 60Co, formed by neutron activation in nuclear reactors, is of concern at Department of Energy sites, such as that at Hanford, and has several industrial applications, including radiotherapy. We address the following questions: Do high levels of Co inhibit enzymatic processes such as Mn(II) oxidation? Can the multicopper oxidase enzyme involved in Mn(II) oxidation facilitate Co(II) oxidation? Lastly, does the organic matter surrounding the oxides affect Co or Mn oxide reactivity? These issues were approached via wet chemical analysis, synchrotron radiation X-ray diffraction (SR-XRD), and extended X-ray absorption fine structure (EXAFS) spectroscopy. In the

  18. White-rot fungi pretreatment combined with alkaline/oxidative pretreatment to improve enzymatic saccharification of industrial hemp.

    Science.gov (United States)

    Xie, Chunliang; Gong, Wenbing; Yang, Qi; Zhu, Zuohua; Yan, Li; Hu, Zhenxiu; Peng, Yuande

    2017-11-01

    White-rot fungi combined with alkaline/oxidative (A/O) pretreatments of industrial hemp woody core were proposed to improve enzymatic saccharification. In this study, hemp woody core were treated with only white rot fungi, only A/O and combined with the two methods. The results showed that Pleurotus eryngii (P. eryngii) was the most effective fungus for pretreatment. Reducing sugars yield was 329mg/g with 30 Filter Paper Unit (FPU)/g cellulase loading when treated 21day. In the A/O groups, the results showed that when treated with 3% NaOH and 3% H 2 O 2 , the yield of reducing sugars was 288mg/g with 30FPU/g cellulase loading. After combination pretreatment with P. eryngii and A/O pretreatment, the reducing sugar yield from enzymatic hydrolysis of combined sample increased 1.10-1.29-fold than that of bio-treated or A/O pretreatment sample at the same conditions, suggesting that P. eryngii combined with A/O pretreatment was an effective method to improve enzyme hydrolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Non-enzymatic lipid oxidation products in biological systems: assessment of the metabolites from polyunsaturated fatty acids.

    Science.gov (United States)

    Vigor, Claire; Bertrand-Michel, Justine; Pinot, Edith; Oger, Camille; Vercauteren, Joseph; Le Faouder, Pauline; Galano, Jean-Marie; Lee, Jetty Chung-Yung; Durand, Thierry

    2014-08-01

    Metabolites of non-enzymatic lipid peroxidation of polyunsaturated fatty acids notably omega-3 and omega-6 fatty acids have become important biomarkers of lipid products. Especially the arachidonic acid-derived F2-isoprostanes are the classic in vivo biomarker for oxidative stress in biological systems. In recent years other isoprostanes from eicosapentaenoic, docosahexaenoic, adrenic and α-linolenic acids have been evaluated, namely F3-isoprostanes, F4-neuroprostanes, F2-dihomo-isoprostanes and F1-phytoprostanes, respectively. These have been gaining interest as complementary specific biomarkers in human diseases. Refined extraction methods, robust analysis and elucidation of chemical structures have improved the sensitivity of detection in biological tissues and fluids. Previously the main reliable instrumentation for measurement was gas chromatography-mass spectrometry (GC-MS), but now the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunological techniques is gaining much attention. In this review, the types of prostanoids generated from non-enzymatic lipid peroxidation of some important omega-3 and omega-6 fatty acids and biological samples that have been determined by GC-MS and LC-MS/MS are discussed. Copyright © 2014. Published by Elsevier B.V.

  20. Evidence for two enzymatic pathways for omega-oxidation of docosanoic acid in rat liver microsomes

    NARCIS (Netherlands)

    Sanders, Robert-Jan; Ofman, Rob; Valianpour, Fredoen; Kemp, Stephan; Wanders, Ronald J. A.

    2005-01-01

    We studied the omega-oxidation of docosanoic acid (C22:0) in rat liver microsomes. C22:0 and 22-hydroxy-docosanoic acid (omega-hydroxy-C22:0) were used as substrates, and the reaction products were analyzed by electrospray ionization mass spectrometry. In the presence of NADPH, omega-oxidation of

  1. Immobilization of enzymatic extracts of Portulaca oleracea cv. roots for oxidizing aqueous bisphenol A.

    Science.gov (United States)

    Matsushima, Kazuki; Kaneda, Hirokazu; Harada, Kazuo; Matsuura, Hideyuki; Hirata, Kazumasa

    2015-05-01

    Water pollution from the release of industrial wastewater is a serious problem for almost every industry. Enzymes from portulaca, Portulaca oleracea cv., have been investigated for their ability to degrade bisphenol A (BPA), one of the well-known estrogenic pollutants. Enzymatic crude extracts from P. oleracea cv. roots were immobilized on aminopropyl-modified glass beads. They maintained BPA metabolic activity over a broad range of pH values and temperatures. The immobilized enzyme was reusable with more than 50 % of its initial activity retained after 12 batch reactions and no loss of activity after storage for 1 month at -30 °C. Thus, the immobilization of extracts from P. oleracea cv. roots is a useful method for removing BPA from industrial wastewater.

  2. Investigation of oxidative degradation and non‐enzymatic browning reactions in krill and fish oils

    DEFF Research Database (Denmark)

    Thomsen, Birgitte Raagaard; Haugsgjerd, Bjørn Ole; Griinari, Mikko

    2013-01-01

    substance (TBARS), conjugated dienes and trienes, and antioxidant content, and (ii) advanced methods such as determination of volatiles content by dynamic headspace (DHS)‐GC/MS, lipid classes, and pyrrole content. In addition, the oxidative stability of the oils was evaluated under accelerated oxidation...... of these classical methods. Nevertheless, the conclusion was supported by the results of the Oxipres™ measurements, which showed that the oxygen consumption was higher for fish oil. Furthermore, the level of most volatile lipid oxidation products was higher for fish oil. The development of Strecker degradation...

  3. Comparison between wet oxidation and steam explosion as pretreatment methods for enzymatic hydrolysis of sugarcane bagasse

    DEFF Research Database (Denmark)

    Medina, Carlos Martín; Marcet, M.; Thomsen, Anne Belinda

    2008-01-01

    , and to a two-fold increase of cellulose content in the pretreated solids, while steam explosion solubilised only 60% of xylan and 35% of lignin and increased cellulose content in the solid material by one third. Wet oxidation formed more aliphatic acids and phenolics, and less furan aldehydes in the liquid...... significantly in steam explosion. This investigation demonstrates the potential of wet oxidation as a promising pretreatment method for enzyme-based bagasse-to-ethanol processes....

  4. Enzymatic improvement of mitochondrial thiol oxidase Erv1 for oxidized glutathione fermentation by Saccharomyces cerevisiae.

    Science.gov (United States)

    Kobayashi, Jyumpei; Sasaki, Daisuke; Hara, Kiyotaka Y; Hasunuma, Tomohisa; Kondo, Akihiko

    2017-03-15

    Oxidized glutathione (GSSG) is the preferred form for industrial mass production of glutathione due to its high stability compared with reduced glutathione (GSH). In our previous study, over-expression of the mitochondrial thiol oxidase ERV1 gene was the most effective for high GSSG production in Saccharomyces cerevisiae cells among three types of different thiol oxidase genes. We improved Erv1 enzyme activity for oxidation of GSH and revealed that S32 and N34 residues are critical for the oxidation. Five engineered Erv1 variant proteins containing S32 and/or N34 replacements exhibited 1.7- to 2.4-fold higher in vitro GSH oxidation activity than that of parental Erv1, whereas the oxidation activities of these variants for γ-glutamylcysteine were comparable. According to three-dimensional structures of Erv1 and protein stability assays, S32 and N34 residues interact with nearby residues through hydrogen bonding and greatly contribute to protein stability. These results suggest that increased flexibility by amino acid replacements around the active center decrease inhibitory effects on GSH oxidation. Over-expressions of mutant genes coding these Erv1 variants also increased GSSG and consequently total glutathione production in S. cerevisiae cells. Over-expression of the ERV1 S32A gene was the most effective for GSSG production in S. cerevisiae cells among the parent and other mutant genes, and it increased GSSG production about 1.5-fold compared to that of the parental ERV1 gene. This is the first study demonstrating the pivotal effects of S32 and N34 residues to high GSH oxidation activity of Erv1. Furthermore, in vivo validity of Erv1 variants containing these S32 and N34 replacements were also demonstrated. This study indicates potentials of Erv1 for high GSSG production.

  5. 3D-copper oxide and copper oxide/few-layer graphene with screen printed nanosheet assembly for ultrasensitive non-enzymatic glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhimei [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Pan, Peng, E-mail: panpeny@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Liu, Xuewen [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Yang, Zhengchun; Wei, Jun [Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Wei, Zhen, E-mail: weizhenxinxi@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China)

    2017-02-01

    Screen-printed copper oxide (CuO) and CuO/few-layer graphene on graphite electrodes were used to fabricate the ultrasensitive nonenzymatic glucose biosensors. Flower-like CuO and flower-like CuO/few-layer graphene composites were prepared by screen-printing method and characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HETEM). On the basis of their cyclic voltammetry (CV) and chronoamperometry results, it was concluded that the addition of graphene to CuO significantly improved the performance of the fabricated glucose sensors, exhibiting high and reproducible sensitivity of 3120 μAmM{sup −1} cm{sup −2} with three linear ranges from 4 μM to 13.5 mM and the detection limit of 4 μM (S/N = 3) in a fast response time of 2 s. In addition, the fabricated sensors could effectively avoid the disturbance by interferents, such as Ascorbic Acid (AA), Uric Acid (UA), and Dopamine (DA). Most importantly, the testing results of real blood serum samples demonstrated that the electrodes were applicable and acceptable for the determination of glucose concentrations in human serum. The efficiencies of two non-enzymatic glucose biosensors for glucose determination were comparable with that of a commercial enzymatic sensor. - Highlights: • The method 2D nanosheet turns to 3D microflower by using screen printing was proposed. • Few-layer graphene added improved the sensor’s performance on base of CuO functional material. • Two ultrasensitive non-enzymatic glucose sensors were successfully fabricated. • The proposed sensor shows a high sensitivity of 3120 μA mM{sup −1} cm{sup −2}.

  6. Pulse electrodeposited nickel-indium tin oxide nanocomposite as an electrocatalyst for non-enzymatic glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Sivasakthi, P.; Ramesh Bapu, G.N.K., E-mail: rameshbapugnk@cecri.res.in; Chandrasekaran, Maruthai

    2016-01-01

    Nickel and nickel-ITO nanocomposite on mild steel substrate were prepared by pulse electrodeposition method from nickel sulphamate electrolyte and were examined as electrocatalysts for non-enzymatic glucose sensing. The surface morphology, chemical composition, preferred orientation and oxidation states of the nickel metal ion in the deposits were characterized by SEM, EDAX, XRD and XPS. Electrochemical sensing of glucose was studied by cyclic voltammetry and amperometry. The modified Ni-ITO nanocomposite electrode showed higher electrocatalytic activity for the oxidation of glucose in alkaline medium and exhibited a linear range from 0.02 to 3.00 mM with a limit of detection 3.74 μM at a signal-to-noise ratio of 3. The higher selectivity, longer stability and better reproducibility of this electrode compared to nickel in the sensing of glucose are pointers for exploitation in practical clinical applications. - Highlights: • Ni-ITO nanocomposites are prepared by pulse electrocodeposition method from nickel sulphamate solutions. • Ni-ITO nanocomposites are characterized using SEM, EDAX, XRD and XPS. • Electrochemical characteristics of the Ni and Ni-ITO nanocomposite deposits are studied by CV and amperometry techniques. • Ni-ITO nanocomposite electrode could be used as sensing material for detection of glucose in practical condition.

  7. Impact of the components of metabolic syndrome on oxidative stress and enzymatic antioxidant activity in essential hypertension.

    Science.gov (United States)

    Abdilla, N; Tormo, M C; Fabia, M J; Chaves, F J; Saez, G; Redon, J

    2007-01-01

    The objective of the present study was to analyze the impact of metabolic syndrome (MS) and its individual components on oxidative stress (OX) and on the activity of antioxidant enzymes of patients with essential hypertension. One hundred and eighty-seven hypertensives, 127 (61.9%) of them having criteria for MS according to the International Diabetes Federation criteria and 30 healthy normotensive subjects were included. OX status was assessed by measuring glutathione oxidized/glutathione reduced and reactive oxygen species-induced byproducts of lipid peroxidation, malondialdehyde, and DNA damage, 8-oxo-dG genomic and mitochondrial. Antioxidant enzymatic activity of Cu/Zn extracellular-superoxide dismutase (SOD) and catalase (CAT) was measured in plasma and glutathione peroxidase 1 in hemolysed erythrocytes. In mononuclear cells, total-SOD activity, CAT and glutathione peroxidase 1, were assessed as well. The OX state in both blood and peripheral mononuclear cells observed in hypertensives were not enhanced by the addition of components of the so-called MS. Likewise, the reduction in the activity of antioxidant enzymes, both extracellular and cytoplasmic, was not affected by the presence of additional components of the MS. Neither the number of components nor the individual addition of each of them, low high-density lipoprotein, triglycerides, abdominal obesity or fasting glucose, further impact in the OX abnormalities observed in those with only hypertension in absence of other components. In conclusion, the present data indicates that contribution of MS components to the OX burden generated by high blood pressure is minimal.

  8. Treatment of groundwater containing Mn(II), Fe(II), As(III) and Sb(III) by bioaugmented quartz-sand filters.

    Science.gov (United States)

    Bai, Yaohui; Chang, Yangyang; Liang, Jinsong; Chen, Chen; Qu, Jiuhui

    2016-12-01

    High concentrations of iron (Fe(II)) and manganese (Mn(II)) often occur simultaneously in groundwater. Previously, we demonstrated that Fe(II) and Mn(II) could be oxidized to biogenic Fe-Mn oxides (BFMO) via aeration and microbial oxidation, and the formed BFMO could further oxidize and adsorb other pollutants (e.g., arsenic (As(III)) and antimony (Sb(III))). To apply this finding to groundwater remediation, we established four quartz-sand columns for treating groundwater containing Fe(II), Mn(II), As(III), and Sb(III). A Mn-oxidizing bacterium (Pseudomonas sp. QJX-1) was inoculated into two parallel bioaugmented columns. Long-term treatment (120 d) showed that bioaugmentation accelerated the formation of Fe-Mn oxides, resulting in an increase in As and Sb removal. The bioaugmented columns also exhibited higher overall treatment effect and anti-shock load capacity than that of the non-bioaugmented columns. To clarify the causal relationship between the microbial community and treatment effect, we compared the biomass of active bacteria (reverse-transcribed real-time PCR), bacterial community composition (Miseq 16S rRNA sequencing) and community function (metagenomic sequencing) between the bioaugmented and non-bioaugmented columns. Results indicated that the QJX1 strain grew steadily and attached onto the filter material surface in the bioaugmented columns. In general, the inoculated strain did not significantly alter the composition of the indigenous bacterial community, but did improve the relative abundances of xenobiotic metabolism genes and Mn oxidation gene. Thus, bioaugmentation intensified microbial degradation/utilization for the direct removal of pollutants and increased the formation of Fe-Mn oxides for the indirect removal of pollutants. Our study provides an alternative method for the treatment of groundwater containing high Fe(II), Mn(II) and As/Sb. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Electrochemical and enzymatic synthesis of oxidative drug metabolites for metabolism studies : Exploring selectivity and yield

    NARCIS (Netherlands)

    Gül, Turan

    2017-01-01

    Metabolism studies of drug molecules play a crucial role in drug discovery and development since the early detection of possibly toxic drug metabolites can save time and money. During the metabolic biotransformation process, oxidation of a drug molecule is catalyzed by specific enzymes which can

  10. Human milk fat substitute from butterfat: production by enzymatic interesterification and evaluation of oxidative stability

    DEFF Research Database (Denmark)

    Sørensen, Ann-Dorit Moltke; Xu, Xuebing; Zhang, Long

    2010-01-01

    Recent data have suggested that the fatty acid composition and molecular structure of fats in infant formulas should be as similar to human milk fat as possible to obtain optimal fat and calcium absorption from the infant formula. This work investigated the possibilities of using enzyme technology...... and butterfat as a material to produce a fat similar to human milk fat with respect to the above parameters. Moreover, the oxidative stability of the enzyme modified human milk fat substitute (HMFS) was compared to the fat blend used for the production of HMFS. Using a combination of enzyme technology......, fractionation and batch deodorization and with butterfat in combination with soybean oil and rapeseed oil as raw materials it was possible to produce HMFS with a molecular structure and fatty acid composition that was very similar to that of human milk fat. The oxidative stability of the HMFS oil was lower than...

  11. Tyrosinase: the four oxidation states of the active site and their relevance to enzymatic activation, oxidation and inactivation.

    Science.gov (United States)

    Ramsden, Christopher A; Riley, Patrick A

    2014-04-15

    Tyrosinase is an enzyme widely distributed in the biosphere. It is one of a group of proteins with a strongly conserved bicopper active centre able to bind molecular oxygen. Tyrosinase manifests two catalytic properties; monooxygenase and oxidase activity. These actions reflect the oxidation states of the active centre. Tyrosinase has four possible oxidation states and the details of their interaction are shown to give rise to the unusual kinetic behaviour of the enzyme. The resting state of the enzyme is met-tyrosinase [Cu(II)2] and activation, associated with a 'lag period', involves reduction to deoxy-tyrosinase [Cu(I)2] which is capable of binding dioxygen to form oxy-tyrosinase [Cu(II)2·O2]. Initially the conversion of met- to deoxy-tyrosinase is brought about by a catechol that is indirectly formed from an ortho-quinone product of tyrosinase action. The primary function of the enzyme is monooxygenation of phenols to ortho-quinones by oxy-tyrosinase. Inactivation of the enzyme results from monooxygenase processing of catechols which can lead to reductive elimination of one of the active-site copper ions and conversion of oxy-tyrosinase to the inactive deact-tyrosinase [Cu(II)Cu(0)]. This review describes the tyrosinase pathways and the role of each oxidation state in the enzyme's oxidative transformations of phenols and catechols. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Impact of primary amine group from aminophospholipids and amino acids on marine phospholipids stability: Non-enzymatic browning and lipid oxidation

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline P.

    2013-01-01

    The main objective of this study was to investigate the oxidative stability and non-enzymatic browning reactions of marine PL in the presence or in the absence of primary amine group from aminophospholipids and amino acids. Marine phospholipids liposomal dispersions were prepared from two authent...... the formation of pyrroles, generated Strecker derived volatiles, decreased the YI development and lowered lipid oxidation. The lower degree of lipid oxidation in liposomal dispersions containing amino acids might be attributed to antioxidative properties of pyrroles or amino acids....

  13. Enzymatic Upgrading of Heavy Crudes via Partial Oxidation or Conversion of PAHs

    Energy Technology Data Exchange (ETDEWEB)

    Borole, A P; Davison, B H; Kuritz, T

    2002-07-01

    The objective of this program was to investigate new enzyme-based technologies for upgrading of heavy oils. Enzymes were selected for screening from those capable of conversion of polyaromatic hydrocarbons (PAHs) reported in the literature. Oxidative reactions of PAHs using hydrogen peroxide as an oxidant with conversion to partially oxidized products were used. The enzymes (lignin peroxidase, cytochrome c) were tested in various organic solvents and found to loose activity in pure organic solvents. A thermodynamic analysis revealed lack of effective interaction between the substrate and enzyme as the cause for low activity. The protein cytochrome c was modified to work in organic media by chemical hydrophobic group attachment. Two different modifications were made: attachment of polyethylene glycol (PEG) and alkyl groups. Alkyl groups, being small could be attached at interior locations within the core of the enzyme and possibly near the active site. Increase in the threshold solvent concentration where maximum enzyme activity occurred indicated potential of this strategy for effective enzyme-substrate interaction. Further improvements in enzyme activity called for other diverse methods due to the unavailability of sufficient chemical modification sites. Genetic techniques were therefore explored for further improvements. These experiments focused on cloning of a gene for the fungal enzyme lignin peroxidase (lip) into yeast Pichia pastoris, which would allow easy manipulation of the gene. However, differences in the fungal and yeast cellular machinery impeded significant expression of the fungal enzyme. Several strategies were explored to allow higher-level expression of the enzyme, which was required for enzyme improvement. The strategies used in this investigation are described in the report. Industrial in-kind support was available throughout the project period. review of the research results was carried out on a regular basis (bimonthly reports and annual

  14. A Comparative evaluation of Graphene oxide based materials for Electrochemical non-enzymatic sensing of Curcumin

    Science.gov (United States)

    Dey, Nibedita; Devasena, T.; Sivalingam, Tamilarasu

    2018-02-01

    This work reports a comparative study on the development of a sensitive voltammetric method for the assay of diferuloylmethane which is fabricated using cost-effective sensing material graphene oxide (GO modified electrode) and reduced graphene oxide (rGO modified electrode) modified on glassy carbon electrode respectively. The prepared materials were characterized using SEM, XRD, FTIR, and Raman techniques to understand the formation. Between the both modified electrodes, rGO modified electrode demonstrated a lower limit detection of 0.9 pM and good signal quality. But, the better linear dynamic range for detection was found to be 1 nm to 100 nM for GO and 0.1 nM to 10 nM for rGO modified electrodes respectively. The repeatability is checked for seven cycles and interference studies were also performed for checking the sensors’ selectivity to curcumin. rGO modified electrode and GO modified electrode both shows specific signals for Diferuloylmethane under conditions similar to physiology. But, with better properties over GO modified electrode, rGO modified electrode is suggested a better candidate for real-time usability in sensing. The detection limit reported is the lowest till date for the given plant drug using any sensing assay.

  15. Molecular Basis for Enzymatic Sulfite Oxidation -- HOW THREE CONSERVED ACTIVE SITE RESIDUES SHAPE ENZYME ACTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, Susan; Rapson, Trevor; Johnson-Winters, Kayunta; Astashkin, Andrei; Enemark, John; Kappler, Ulrike

    2008-11-10

    Sulfite dehydrogenases (SDHs) catalyze the oxidation and detoxification of sulfite to sulfate, a reaction critical to all forms of life. Sulfite-oxidizing enzymes contain three conserved active site amino acids (Arg-55, His-57, and Tyr-236) that are crucial for catalytic competency. Here we have studied the kinetic and structural effects of two novel and one previously reported substitution (R55M, H57A, Y236F) in these residues on SDH catalysis. Both Arg-55 and His-57 were found to have key roles in substrate binding. An R55M substitution increased Km(sulfite)(app) by 2-3 orders of magnitude, whereas His-57 was required for maintaining a high substrate affinity at low pH when the imidazole ring is fully protonated. This effect may be mediated by interactions of His-57 with Arg-55 that stabilize the position of the Arg-55 side chain or, alternatively, may reflect changes in the protonation state of sulfite. Unlike what is seen for SDHWT and SDHY236F, the catalytic turnover rates of SDHR55M and SDHH57A are relatively insensitive to pH (~;;60 and 200 s-1, respectively). On the structural level, striking kinetic effects appeared to correlate with disorder (in SDHH57A and SDHY236F) or absence of Arg-55 (SDHR55M), suggesting that Arg-55 and the hydrogen bonding interactions it engages in are crucial for substrate binding and catalysis. The structure of SDHR55M has sulfate bound at the active site, a fact that coincides with a significant increase in the inhibitory effect of sulfate in SDHR55M. Thus, Arg-55 also appears to be involved in enabling discrimination between the substrate and product in SDH.

  16. New parameters for evaluating the quality of commercial krill oil capsules from the aspect of lipid oxidation and non-enzymatic browning reactions

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Bruheim, Inge; Jacobsen, Charlotte

    2015-01-01

    , and their alkyl derivatives, sulphur and amino compounds). The data of chemical composition of krill oil were correlated well with those from volatile measurement. Through investigating volatile profile, new insights into the lipid oxidation and non-enzymatic browning reactions in krill oil were obtained...... different commercial krill oil capsules through parameters such as: investigation of chemical compositions (bioactive compounds such as phospholipids, n-3 polyunsaturated fatty acids, antioxidants), hydrophobic pyrroles, and volatile profiles (lipid and Strecker-derived volatiles, pyridines, pyrazines...... provides new parameters to differentiate the quality of krill oil through the measurement of bioactive compounds and hydrophobic pyrroles in krill oil, and investigation of volatile profiles of krill oil from the aspect of lipid oxidation and non-enzymatic browning reactions....

  17. The Experimental Degradation of Microorganisms Exposed to Mn(II) and SiO2 Over Time

    Science.gov (United States)

    Schelble, R. T.; Hall, J. A.; Fogel, M. L.; Jahnke, L. L.; Nealson, K. H.; Steele, A.

    2005-12-01

    The sedimentary origin of early Proterozoic massive manganese deposits in the geological record is often attributed in part to the impact of biological processes. Although it seems possible that widespread algal blooms in near-shore oceanic environments caused the oxidation of reduced manganese from ocean waters, direct evidence of microorganisms (i.e. microfossils or chemical biosignatures) have not been identified in early Proterozoic manganiferous deposits. The purpose of this study was to identify the potential for biosignature preservation in remnant ancient manganese deposits by monitoring the degradation of modern microorganisms exposed to varying concentrations of Mn(II). Given that most early Proterozoic microfossils have been found in siliceous rocks, similar experiments were carried out using silica-rich solutions for comparison. Bacillus subtilis (gram-positive) and Escherichia coli (gram-negative) were exposed to various Mn(II)- and silica-rich solutions over a period of 180 days. The degradation of a short-duration biomarker (DNA), and longer-duration biomarkers (phospholipid fatty acids and their derivative n-alkanes) were investigated. The degradation of DNA was quantified using real time PCR (RT-PCR) and microorganism specific and general bacteria primers. DNA longevity decreased with higher concentrations of manganese (up to 1000 ppm Mn(II)) when compared with control microorganisms suspended in solutions without manganese. This effect was more dramatic in the E. coli incubations. Relatively steady decreases in the longevity of B. subtilis DNA were observed when cells were exposed to Mn(II). This may be due to the ability of the organism to sporulate, which may protect the DNA from rapid degradation. B. subtilis DNA persisted longer when cells were exposed to undersaturated SiO2 solution (100 ppm SiO2), than those exposed to supersaturated SiO2 solutions (1000 ppm and 3000 ppm). The preservation potential of E. coli DNA showed no differences

  18. Effects of cerium oxide nanoparticles on soil enzymatic activities and wheat grass nutrients uptake

    Science.gov (United States)

    Li, Biting; Chen, Yirui; Bai, Lingyun; Jacobson, Astrid; Darnault, Christophe

    2015-04-01

    The US National Science Foundation estimated that the use of nanomaterials and nanotechnology would reach a global market value of 1 million this year. Concomitant with the wide applications of nanoparticles is an increasing risk of adverse effects to the environment and human health. As a common nanomaterial used as a fuel catalyst and polish material, cerium (IV) oxide nanoparticles (CeO2 NP) were tested for their potential impact on soil health and plant growth. Through exposure by air, water, and solid deposition, nanoparticles may accumulate in soils and impact agricultural systems. The objectives of this research were to determine whether CeO2 NPs affect the growth of wheat grass and selected soil enzyme activities chose as indicators of soil health. Wheat grass was grown in plant boxes containing CeO2 NPs mixed with agricultural soil at different concentrations. Two control groups were included: one consisting of soil with plants but no CeO2 NPs, and one containing only soil, i.e., no NP or wheat plants added. The plants were grown for 10 weeks and harvested every two weeks in a laboratory under sodium growth lights. At the end of the each growing period, two weeks, soils were assayed for phosphatase, β-glucosidase, and urease activities, and NPK values. Spectrophotometer analyses were used to assess enzyme activities, and NPK values were tested by Clemson Agricultural Center. Wheat yields were estimated by shoot and root lengths and weights.

  19. Enzymatic oxidation of cholesterol: properties and functional effects of cholestenone in cell membranes.

    Directory of Open Access Journals (Sweden)

    Maarit Neuvonen

    Full Text Available Bacterial cholesterol oxidase is commonly used as an experimental tool to reduce cellular cholesterol content. That the treatment also generates the poorly degradable metabolite 4-cholesten-3-one (cholestenone has received less attention. Here, we investigated the membrane partitioning of cholestenone using simulations and cell biological experiments and assessed the functional effects of cholestenone in human cells. Atomistic simulations predicted that cholestenone reduces membrane order, undergoes faster flip-flop and desorbs more readily from membranes than cholesterol. In primary human fibroblasts, cholestenone was released from membranes to physiological extracellular acceptors more avidly than cholesterol, but without acceptors it remained in cells over a day. To address the functional effects of cholestenone, we studied fibroblast migration during wound healing. When cells were either cholesterol oxidase treated or part of cellular cholesterol was exchanged for cholestenone with cyclodextrin, cell migration during 22 h was markedly inhibited. Instead, when a similar fraction of cholesterol was removed using cyclodextrin, cells replenished their cholesterol content in 3 h and migrated similarly to control cells. Thus, cholesterol oxidation produces long-term functional effects in cells and these are in part due to the generated membrane active cholestenone.

  20. Enzymatic Oxidation of Cholesterol: Properties and Functional Effects of Cholestenone in Cell Membranes

    Science.gov (United States)

    Neuvonen, Maarit; Manna, Moutusi; Mokkila, Sini; Javanainen, Matti; Rog, Tomasz; Liu, Zheng; Bittman, Robert; Vattulainen, Ilpo; Ikonen, Elina

    2014-01-01

    Bacterial cholesterol oxidase is commonly used as an experimental tool to reduce cellular cholesterol content. That the treatment also generates the poorly degradable metabolite 4-cholesten-3-one (cholestenone) has received less attention. Here, we investigated the membrane partitioning of cholestenone using simulations and cell biological experiments and assessed the functional effects of cholestenone in human cells. Atomistic simulations predicted that cholestenone reduces membrane order, undergoes faster flip-flop and desorbs more readily from membranes than cholesterol. In primary human fibroblasts, cholestenone was released from membranes to physiological extracellular acceptors more avidly than cholesterol, but without acceptors it remained in cells over a day. To address the functional effects of cholestenone, we studied fibroblast migration during wound healing. When cells were either cholesterol oxidase treated or part of cellular cholesterol was exchanged for cholestenone with cyclodextrin, cell migration during 22 h was markedly inhibited. Instead, when a similar fraction of cholesterol was removed using cyclodextrin, cells replenished their cholesterol content in 3 h and migrated similarly to control cells. Thus, cholesterol oxidation produces long-term functional effects in cells and these are in part due to the generated membrane active cholestenone. PMID:25157633

  1. Antioxidant and enzymatic responses to oxidative stress induced by pre-harvest water supply reduction and ripening on mango (Mangifera indica L. cv. 'Cogshall') in relation to carotenoid content

    OpenAIRE

    Rosalie , Rémy; Joas , Jacques; Deytieux-Belleau , Christelle; Vulcain , Emmanuelle; Payet , Bertrand; Dufossé , Laurent; Léchaudel , Mathieu

    2015-01-01

    International audience; The effects of a reduction in water supply during fruit development and postharvest fruit ripening on the oxidative status and the antioxidant defense system were studied in the mango fruit (Mangifera indica L.) cv. Cogshall. Changes in non-enzymatic (ascorbate) and enzymatic (SOD, CAT, APX, MDHAR, DHAR and GR) antioxidants, as well as oxidative parameters (H 2 O 2 and MDA) and major carotenoids, were measured in unripe and ripe fruits from well-irrigated and non-irrig...

  2. A non-enzymatic amperometric hydrogen peroxide sensor based on iron nanoparticles decorated reduced graphene oxide nanocomposite.

    Science.gov (United States)

    Amanulla, Baishnisha; Palanisamy, Selvakumar; Chen, Shen-Ming; Velusamy, Vijayalakshmi; Chiu, Te-Wei; Chen, Tse-Wei; Ramaraj, Sayee Kannan

    2017-02-01

    A simple and facile green process was used for the synthesis of iron nanoparticles (FeNPs) decorated reduced graphene oxide (rGO) nanocomposite by using Ipomoea pes-tigridis leaf extract as a reducing and stabilizing agent. The as-prepared rGO/FeNPs nanocomposite was characterized by transmission electron microscopy, X-ray spectroscopy and Fourier transform infrared spectroscopy. The nanocomposite was further modified on the glassy carbon electrode and used for non-enzymatic sensing of hydrogen peroxide (H 2 O 2 ). Cyclic voltammetry results reveal that rGO/FeNPs nanocomposite has excellent electro-reduction behavior to H 2 O 2 when compared to the response of FeNPs and rGO modified electrodes. Furthermore, the nanocomposite modified electrode shows 9 and 6 folds enhanced reduction current response to H 2 O 2 than that of rGO and FeNPs modified electrodes. Amperometric method was further used to quantify the H 2 O 2 using rGO/FeNPs nanocomposite, and the response was linear over the concentration ranging from 0.1μM to 2.15mM. The detection limit and sensitivity of the sensor were estimated as 0.056μM and 0.2085μAμM -1 cm -2 , respectively. The fabricated sensor also utilized for detection of H 2 O 2 in the presence of potentially active interfering species, and found high selectivity towards H 2 O 2 . Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Dietary enzymatically treated Artemisia annua L. supplementation alleviates liver oxidative injury of broilers reared under high ambient temperature

    Science.gov (United States)

    Wan, Xiaoli; Zhang, Jingfei; He, Jintian; Bai, Kaiwen; Zhang, Lili; Wang, Tian

    2017-09-01

    Heat stress induced by high ambient temperature is a major concern in commercial broiler production. To evaluate the effects of dietary enzymatically treated Artemisia annua L. (EA) supplementation on growth performance and liver oxidative injury of broilers reared under heat stress, a total of 320 22-day-old male broilers were randomly allotted into five groups with eight replicates of eight birds each. Broilers in the control group were housed at 22 ± 1 °C and fed the basal diet. Broilers in the HS, HS-EA1, HS-EA2, and HS-EA3 groups were fed basal diet supplemented with 0, 0.75, 1.00, and 1.25 g/kg EA, respectively, and reared under cyclic high temperature (34 ± 1 °C for 8 h/day and 22 ± 1 °C for 16 h/day). Broilers fed EA diets had higher final body weight, average daily body weight gain, and average daily feed intake, as well as liver concentration of reduced glutathione, activities of antioxidant enzymes, abilities to inhibit hydroxyl radical and superoxide radical (HS-EA2 and HS-EA3), and lower liver concentrations of reactive oxygen metabolites, malondialdehyde, and protein carbonyl (HS-EA1, HS-EA2, and HS-EA3) than HS group ( P < 0.05). EA treatment downregulated the mRNA levels of heat shock proteins 70 and 90, upregulated the mRNA levels of nuclear factor erythroid 2-related factor 2 (HS-EA1, HS-EA2, and HS-EA3) and heme oxygenase 1 (HS-EA2 and HS-EA3) in liver of heat-treated broilers ( P < 0.05). In conclusion, EA alleviated heat stress-induced growth depression and liver oxidative injury in broilers, possibly through improving the antioxidant capacity and regulating the pertinent mRNA expression. The appropriate inclusion level of EA in broiler diet is 1.00-1.25 g/kg.

  4. Investigation of the effects of the chronic administration of some antihypertensive drugs on enzymatic and non-enzymatic oxidant/antioxidant parameters in rat ovarian tissue.

    Science.gov (United States)

    Salman, Suleyman; Kumbasar, Serkan; Yilmaz, Mehmet; Kumtepe, Yakup; Borekci, Bunyamin; Bakan, Ebubekir; Suleyman, Halis

    2011-11-01

    In this study, effects of chronic antihypertensive drug (clonidine, methyldopa, amlodipine, ramipril, and rilmenidine) treatment on antioxidant-oxidant parameters were investigated in rat ovarian tissue. Chronic drug administration for 30 days and at the end, biochemical examinations (total glutathione (tGSH), glutathione peroxidase (GPO), glutathione reductase (GR), glutathione s-transferase (GST), superoxide dismutase (SOD), nitric oxide (NO), catalase (CAT), malondialdehyde (MDA), and myeloperoxidase (MPO) analyses) were performed. The levels of glutathione (GSH) and NO, and the activities of GPO, GR, GST, SOD, and CAT were measured the lowest in ramiprile group. Also in ramiprile group, the level of MDA and the activity of MPO was the highest. We divided the drugs into four groups according to their biochemical side effect potentials in ovarian tissue: (I) Drugs which have no clear negative effect on ovarian tissue: clonidine, rilmenidine; (II) Drugs which have mild negative effect on ovarian tissue: methyldopa; (III) Drugs which have moderate negative effect on ovarian tissue: amlodipine; (IV) Drugs which have severe negative effect on ovarian tissue: ramipril. These data might be useful in the selection of the least toxic antihypertensive drug in pregnant and/or normal females.

  5. Oxidative degradation and non-enzymatic browning due to the interaction between oxidised lipids and primary amine groups in different marine PL emulsions

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline P.

    2012-01-01

    levels of triglycerides in the emulsions. The oxidative and hydrolytic stability of emulsions was investigated through measurement of peroxide value, free fatty acids, and 31P NMR during storage at 2 C for up to 32 days. The oxidative stability of marine PL emulsions during storage was further......Due to the beneficial health effects of marine phospholipids (PL) there is an increasing industrial interest in using them for nutritional applications including emulsified foods. This study was undertaken to investigate both oxidative and hydrolytic stability of marine PL emulsions in relation...... investigated through the measurement of secondary volatile compounds by solid-phase microextraction (SPME) and dynamic headspace (DHS) connected to gas chromatography (GC–MS). Non-enzymatic browning reactions were investigated through the measurement of Strecker derived volatiles, colour changes and pyrrole...

  6. Standardization and quality control in quantifying non-enzymatic oxidative protein modifications in relation to ageing and disease

    DEFF Research Database (Denmark)

    Nedić, Olgica; Rogowska-Wrzesinska, Adelina; Rattan, Suresh I S

    2015-01-01

    Post-translational modifications (PTM) of proteins determine the activity, stability, specificity, transportability and lifespan of a protein. Some PTM are highly specific and regulated involving various enzymatic pathways, but there are other non-enzymatic PTM (nePTM), which occur stochastically...... being fully active to totally inactive molecules. Determination of the type and the amount (abundance) of nePTM is essential for establishing connection between specific protein structure and specific biological role. This article summarizes analytical demands for reliable quantification of ne......PTM, including requirements for the assay performance, standardization and quality control, and points to the difficulties, uncertainties and un-resolved issues....

  7. Physical and oxidative stability of fish oil-in-water emulsions fortified with enzymatic hydrolysates from common carp (Cyprinus carpio) roe

    DEFF Research Database (Denmark)

    Ghelichi, Sakhi; Sørensen, Ann-Dorit Moltke; García Moreno, Pedro Jesús

    2017-01-01

    Physical and oxidative stability of 5% (by weight) cod liver oil-in-water emulsions fortified with common carp (C. carpio) roe protein hydrolysate (CRPH) were examined. CRPH was obtained by enzymatic hydrolysis of discarded roe by using Alcalase 2.4 L for 30, 60, 90, and 120 min to yield different...... degrees of hydrolysis (DH). All the hydrolysates showed in vitro antioxidant activity in terms of radical scavenging and chelating properties. CRPH-containing emulsions had significantly smaller droplets than control (p ...

  8. Enzymatic synthesis of organophosphorus compounds

    International Nuclear Information System (INIS)

    Kolodiazhnyi, Oleg I

    2011-01-01

    Data on biocatalytic methods for the preparation of chiral organophosphorus compounds are generalized and described systematically. Various examples of enzymatic and microbiological synthesis of hydroxyphosphonates, aminophosphonates, phosphinites, phosphine oxides and tertiary phosphines are discussed. The bibliography includes 154 references.

  9. Enzymatic synthesis of organophosphorus compounds

    Science.gov (United States)

    Kolodiazhnyi, Oleg I.

    2011-09-01

    Data on biocatalytic methods for the preparation of chiral organophosphorus compounds are generalized and described systematically. Various examples of enzymatic and microbiological synthesis of hydroxyphosphonates, aminophosphonates, phosphinites, phosphine oxides and tertiary phosphines are discussed. The bibliography includes 154 references.

  10. Effect of temperature towards lipid oxidation and non-enzymatic browning reactions in krill oil upon storage

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Bruheim, I.; Haugsgjerd, B.O.

    2014-01-01

    was assessed by peroxide value and anisidine value, measurement of lipid derived volatiles, lipid classes and antioxidants. The non-enzymatic browning reactions were assessed through the measurement of pyrroles, free amino acids content and Strecker-derived volatiles. The increase of incubation temperature...

  11. Pretreatment of sugarcane bagasse using the advanced oxidation process by electron beam for enzymatic hydrolysis of cellulose

    International Nuclear Information System (INIS)

    Ribeiro, Marcia Almeida

    2013-01-01

    The sugar cane bagasse is a renewable energy source and a raw material promise in the biofuel production, once represents about 30% of glucose contained in the plant with the potential to be hydrolyzed and then converted to ethanol. The bagasse is composed of cellulose, straight chain of glucose, of hemicellulose, an amorphous polymer consisting of xylose, arabinose, galactose, and mannose, and of lignin, a complex polymer consisting of fenilpropan units that acts as waterproof coating on the fibers, which is hard to remove due its recalcitrant nature. The aim of this work was to study the electron beam processing as a pretreatment of sugarcane bagasse to enzymatic hydrolysis of cellulose. The pretreatment of sugarcane bagasse is one of the most important steps to make this material economically viable and competitive on the energy production. As a pretreatment the electron beam processing can weak the hemicellulose and lignin structures by the action highly reactive radicals that breaks the links, reducing the degree of polymerization fibers. It was evaluated the chemical and structural modifications on fibers caused by the irradiation, the enzymatic hydrolysis of electron beam as the only pretreatment and combined to steam explosion. For enzymatic hydrolysis it was used the commercial enzymes from Novozymes. The radiation processing promotes changes in structure and composition of sugarcane bagasse, increasing the solubility, that is related to hemicellulose and cellulose cleavage, and also increasing the enzymatic conversion yield. In the case of exploded bagasse there is no changes in the enzymatic hydrolysis yield, however the electron beam processing promoted a 67% reduction of furfural, that is formed in the steam explosion process. (author)

  12. Biological Superoxide In Manganese Oxide Formation

    Science.gov (United States)

    Hansel, C.; Learman, D.; Zeiner, C.; Santelli, C. M.

    2011-12-01

    Manganese (Mn) oxides are among the strongest sorbents and oxidants within the environment, controlling the fate and transport of numerous elements and the degradation of recalcitrant carbon. Both bacteria and fungi mediate the oxidation of Mn(II) to Mn(III/IV) oxides but the genetic and biochemical mechanisms responsible remain poorly understood. Furthermore, the physiological basis for microbial Mn(II) oxidation remains an enigma. We have recently reported that a common marine bacterium (Roseobacter sp. AzwK-3b) oxidizes Mn(II) via reaction with extracellular superoxide (O2-) produced during exponential growth. Here we expand this superoxide-mediated Mn(II) oxidation pathway to fungi, introducing a surprising homology between prokaryotic and eukaryotic metal redox processes. For instance, Stibella aciculosa, a common soil Ascomycete filamentous fungus, precipitates Mn oxides at the base of asexual reproductive structures (synnemata) used to support conidia (Figure 1). This distribution is a consequence of localized production of superoxide (and it's dismutation product hydrogen peroxide, H2O2), leading to abiotic oxidation of Mn(II) by superoxide. Disruption of NADPH oxidase activity using the oxidoreductase inhibitor DPI leads to diminished cell differentiation and subsequent Mn(II) oxidation inhibition. Addition of Cu(II) (an effective superoxide scavenger) leads to a concentration dependent decrease in Mn oxide formation. We predict that due to the widespread production of extracellular superoxide within the fungal and likely bacterial kingdoms, biological superoxide may be an important contributor to the cycling of Mn, as well as other metals (e.g., Hg, Fe). Current and future explorations of the genes and proteins involved in superoxide production and Mn(II) oxidation will ideally lend insight into the physiological and biochemical basis for these processes.

  13. Physicochemical properties of 3,4,5-trimethoxybenzoates of Mn(II, Co(II, Ni(II and Zn(II

    Directory of Open Access Journals (Sweden)

    W. FERENC

    2005-09-01

    Full Text Available The complexes of Mn(II, Co(II, Ni(II, Cu(II and Zn(II with 3,4,5-trimethoxybenzoic acid anion of the formula: M(C10H11O52·nH2O, where n = 6 for Ni(II, n = 1 for Mn(II, Co(II, Cu(II, and n = 0 for Zn, have been synthesized and characterized by elemental analysis, IR spectroscopy, X–ray diffraction measurements, thermogravimetry and magnetic studies. They are crystalline compounds characterized by various symmetry. They decompose in various ways when heated in air to 1273 K. At first, they dehydrate in one step and form anhydrous salts. The final products of decomposition are oxides of the respective metals (Mn2O3, Co3O4, NiO, CuO, ZnO. The solubilities of the analysed complexes in water at 293 K are in the orders of 10-2 – 10-4 mol dm-3. The magnetic susceptibilities of the Mn(II, Co(II, Ni(II and Cu(II complexes were measured over the range of 76–303 K and the magnetic moments were calculated. The results show that the 3,4,5-trimethoxybenzoates of Mn(II, Co(II and Ni(II are high-spin complexes but that of Cu(II forms a dimer [Cu2(C10H11O54(H2O2]. The carboxylate groups bind as monodentate or bidentate chelating or bridging ligands.

  14. Mn(II) regulation of lignin peroxidases and manganese-dependent peroxidases from lignin-degrading white rot fungi

    International Nuclear Information System (INIS)

    Bonnarme, P.; Jeffries, T.W.

    1990-01-01

    Two families of peroxidases-lignin peroxidase (LiP) and manganese-dependent lignin peroxidase (MnP)-are formed by the lignin-degrading white rot basidiomycete Phanerochaete chrysosporium and other white rot fungi. Isoenzymes of these enzyme families carry out reactions important to the biodegradation of lignin. This research investigated the regulation of LiP and MnP production by Mn(II). In liquid culture, LiP titers varied as an inverse function of and MnP titers varied as a direct function of the Mn(II) concentration. The extracellular isoenzyme profiles differed radically at low and high Mn(II) levels, whereas other fermentation parameters, including extracellular protein concentrations, the glucose consumption rate, and the accumulation of cell dry weight, did not change significantly with the Mn(II) concentration. In the absence of Mn(II), extracellular LiP isoenzymes predominated, whereas in the presence of Mn(II), MnP isoenzymes were dominant. The release of 14 CO 2 from 14 C-labeled dehydrogenative polymerizate lignin was likewise affected by Mn(II). The rate of 14 CO 2 release increased at low Mn(II) and decreased at high Mn(II) concentrations. This regulatory effect of Mn(II) occurred with five strains of P. chrysosporium, two other species of Phanerochaete, three species of Phlebia, Lentinula edodes, and Phellinus pini

  15. Manganese and iron oxidation by fungi isolated from building stone.

    Science.gov (United States)

    de la Torre, M A; Gomez-Alarcon, G

    1994-01-01

    Acid and nonacid generating fungal strains isolated from weathered sandstone, limestone, and granite of Spanish cathedrals were assayed for their ability to oxidize iron and manganese. In general, the concentration of the different cations present in the mineral salt media directly affected Mn(IV) oxide formation, although in some cases, the addition of glucose and nitrate to the culture media was necessary. Mn(II) oxidation in acidogenic strains was greater in a medium containing the highest concentrations of glucose, nitrate, and manganese. High concentrations of Fe(II), glucose, and mineral salts were optimal for iron oxidation. Mn(IV) precipitated as oxides or hydroxides adhered to the mycelium. Most of the Fe(III) remained in solution by chelation with organic acids excreted by acidogenic strains. Other metabolites acted as Fe(III) chelators in nonacidogenic strains, although Fe(III) deposits around the mycelium were also detected. Both iron and manganese oxidation were shown to involve extracellular, hydrosoluble enzymes, with maximum specific activities during exponential growth. Strains able to oxidize manganese were also able to oxidize iron. It is concluded that iron and manganese oxidation reported in this work were biologically induced by filamentous fungi mainly by direct (enzymatic) mechanisms.

  16. Novel differential refractometry study of the enzymatic degradation kinetics of poly(ethylene oxide)-b-poly(epsilon-caprolactone) particles dispersed in water.

    Science.gov (United States)

    Lam, HiuFung; Gong, Xiangjun; Wu, Chi

    2007-02-22

    A poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) diblock copolymer was micronized into small micelle-like particles (approximately 80 nm) via dialysis-induced microphase inversion. The enzymatic biodegradation of the PCL portion of these particles in water was in situ investigated inside a recently developed novel differential refractometer. Using this refractometry method, we were able to monitor the real-time biodegradation via the refractive index change (Deltan) of the dispersion because Deltan is directly proportional to the particle mass concentration. We found that the degradation rate is proportional to either the polymer or enzyme concentration. Our results directly support previous speculation on the basis of the light-scattering data that the biodegradation follows the first-order kinetics for a given enzyme concentration. This study not only leads to a better understanding of the enzymatic biodegradation of PCL, but also demonstrates a novel, rapid, noninvasive, and convenient way to test the degradability of polymers.

  17. Thermoanalytical studies of cimetidine and complexes with Mn(II Co(II and Ni(II

    Directory of Open Access Journals (Sweden)

    Ana Carolina Mendes Hacke

    2014-02-01

    Full Text Available Cimetidine is an important hydrogen histamine receptor and can coordinate metal ions in blood plasma. The stability of cimetidine and its complexes with Mn(II, Co(II and Ni(II was evaluated by studies of thermogravimetry (TG and differential thermal analysis (DTA. Cimetidine was thermally stable up to near 190 °C and above this temperature the thermal decomposition occurred in two stages. Complexes of [Mn(HCm2]Cl2, [Co(Cm2]Cl2 and [Ni(Cm2]Cl2 showed a similar behavior. The pyrolytic decomposition occurred in two stages at temperatures above 250 oC. A residue for each complex was detected at the end of the decomposition process. This probably corresponds to the respective metal oxide.

  18. Evaluation of a silver-based electrocatalyst for the determination of hydrogen peroxide formed via enzymatic oxidation.

    Science.gov (United States)

    Gonzalez-Macia, Laura; Smyth, Malcolm R; Killard, Anthony J

    2012-09-15

    Silver paste electrodes modified with lyotropic phases formed from dodecyl benzenesulphonic acid and KCl were used as the reductant in the determination of the hydrogen peroxide released from the enzymatic reaction of glucose oxidase with glucose and oxygen. The response of the modified electrode to hydrogen peroxide reduction (-0.1 V vs. Ag/AgCl) was shown to suffer from interference resulting from co-localization of enzyme and substrate at the electrode surface. This interference was eradicated by the introduction of a perm-selective membrane in the form of cellulose acetate. This further facilitated immobilization of the enzyme while allowing diffusion of the generated peroxide to the electrode. The resulting configuration was shown to be capable of the analytical determination of glucose. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Enzymatic decontamination

    Directory of Open Access Journals (Sweden)

    Edyta Prusińska-Kurstak

    2014-12-01

    Full Text Available [b]Abstract[/b]. This paper is devoted to the methods of decontamination of weapons of mass destruction (biological and chemical, based on the use of protein catalysts of chemical reactions — enzymes. This paper presents the possibility of using enzymes to neutralize the harmful and destructive to the environment and human chemicals used in weapons of mass destruction. The mechanism of the enzymatic reaction is showed. These are the possibilities of using lysozyme as destructor dangerous bacteria (E. coli, anthrax Bacillus anthracis and their spores. The advantages and disadvantages of chemical and enzymatic methods of decontamination have been compared. It was found that under certain conditions the enzymes can be an alternative to chemical methods of decontamination of weapons of mass destruction.[b]Keywords[/b]: decontamination, weapons of mass destruction, enzymes

  20. Fabrication of sensitive enzymatic biosensor based on multi-layered reduced graphene oxide added PtAu nanoparticles-modified hybrid electrode.

    Directory of Open Access Journals (Sweden)

    Md Faruk Hossain

    Full Text Available A highly sensitive amperometric glucose sensor was developed by immobilization of glucose oxidase (GOx onto multi-layer reduced graphene oxide (MRGO sheets decorated with platinum and gold flower-like nanoparticles (PtAuNPs modified Au substrate electrode. The fabricated MRGO/PtAuNPs modified hybrid electrode demonstrated high electrocatalytic activities toward oxidation of H2O2, to which it had a wide linear response that ranged from 0.5 to 8 mM (R2 = 0.997, and high sensitivity of 506.25 μA/mMcm2. Furthermore, glucose oxidase-chitosan composite and cationic polydiallyldimethylammonium chloride (PDDA were assembled by a casting method on the surface of MRGO/PtAuNPs modified electrode. This as-fabricated hybrid biosensor electrode exhibited high electrocatalytic activity for the detection of glucose in PBS. It demonstrated good analytical properties in terms of a low detection limit of 1 μM (signal-to-noise ratio of 3, short response time (3 s, high sensitivity (17.85 μA/mMcm2, and a wide linear range (0.01-8 mM for glucose sensing. These results reveal that the newly developed sensing electrode offers great promise for new type enzymatic biosensor applications.

  1. Fabrication of sensitive enzymatic biosensor based on multi-layered reduced graphene oxide added PtAu nanoparticles-modified hybrid electrode.

    Science.gov (United States)

    Hossain, Md Faruk; Park, Jae Y

    2017-01-01

    A highly sensitive amperometric glucose sensor was developed by immobilization of glucose oxidase (GOx) onto multi-layer reduced graphene oxide (MRGO) sheets decorated with platinum and gold flower-like nanoparticles (PtAuNPs) modified Au substrate electrode. The fabricated MRGO/PtAuNPs modified hybrid electrode demonstrated high electrocatalytic activities toward oxidation of H2O2, to which it had a wide linear response that ranged from 0.5 to 8 mM (R2 = 0.997), and high sensitivity of 506.25 μA/mMcm2. Furthermore, glucose oxidase-chitosan composite and cationic polydiallyldimethylammonium chloride (PDDA) were assembled by a casting method on the surface of MRGO/PtAuNPs modified electrode. This as-fabricated hybrid biosensor electrode exhibited high electrocatalytic activity for the detection of glucose in PBS. It demonstrated good analytical properties in terms of a low detection limit of 1 μM (signal-to-noise ratio of 3), short response time (3 s), high sensitivity (17.85 μA/mMcm2), and a wide linear range (0.01-8 mM) for glucose sensing. These results reveal that the newly developed sensing electrode offers great promise for new type enzymatic biosensor applications.

  2. [Isolation and identification of hydrogen-oxidizing bacteria producing 1-aminocyclopropane-1-carboxylate deaminase and the determination of enzymatic activity].

    Science.gov (United States)

    Fu, Bo; Wang, Weiwei; Tang, Ming; Chen, Xingdu

    2009-03-01

    We used Medicago sativa rhizosphere in Shaanxi province of China to isolate and identify hydrogen-oxidizing bacteria that produced ACC (1-aminocyclopropane-1-carboxylate) deaminase, and then studied the mechanism why they can promote the growth of plants. Hydrogen-oxidizing bacteria were isolated by gas-cycle incubation system. We studied the morphological character, physiological characteristics, 16S rDNA sequence analysis and built the phylogenic tree. Thin layer chromatography was used to isolate the strain that produced ACC deaminase. Ninhydrin reaction was used to test the enzyme activity. In total 37 strains were isolated, 8 of which could oxidize H2 strongly and grow chemolithoautotrophically. We initially identified them as hydrogen-oxidizing bacteria. Only strain WMQ-7 produced ACC deaminase among these 8 strains. Morphological and physiological characteristics analysis showed that strain WMQ-7 was essentially consistent with Pseudomonas putida. The 16S rDNA sequence analysis (GenBank accession number EU807744) suggested that strain WMQ-7 was clustered together with Pseudomonas putida in phylogenetic tree, with the sequence identity of 99%. Based on all these results, strain WMQ-7 was identified as Pseudomonas putida. The enzyme activity of strain WMQ-7 was 0.671 U/microg. A strain producing ACC deaminase was identified and tested.

  3. Enzymatic desulfurization of coal

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Y.N.; Crooker, S.C.; Kitchell, J.P.; Nochur, S.V.

    1991-05-16

    The overall objective of this program was to investigate the feasibility of an enzymatic desulfurization process specifically intended for organic sulfur removal from coal. Toward that end, a series of specific objectives were defined: (1) establish the feasibility of (bio)oxidative pretreatment followed by biochemical sulfate cleavage for representative sulfur-containing model compounds and coals using commercially-available enzymes; (2) investigate the potential for the isolation and selective use of enzyme preparations from coal-utilizing microbial systems for desulfurization of sulfur-containing model compounds and coals; and (3) develop a conceptual design and economic analysis of a process for enzymatic removal of organic sulfur from coal. Within the scope of this program, it was proposed to carry out a portion of each of these efforts concurrently. (VC)

  4. Status of plasma nitric oxide and non-enzymatic antioxidants before and after antipsychotic treatment in Nigerian patients with schizophrenia

    Directory of Open Access Journals (Sweden)

    Ganiyu Olatubosun Arinola

    2009-02-01

    Full Text Available

    • BACKGROUND: Recently, it is proposed that oxidant-antioxidant imbalance may have a role in the pathophysiology of schizophrenia. The present study was performed to assess differences in plasma levels of nitric oxide (as oxidant, caeruloplasmin (secondary antioxidant, and antioxidant trace metals (Zn, Se, Mn, Cu and Fe in patients with schizophrenia compared with healthy controls. Our secondary aim was to further evaluate the impact of psychopharmacologic treatment on these parameters.
    • METHODS: Plasma levels of nitric oxides (NO, caeruloplasmin, zinc (Zn, selenium (Se, manganese (Mn, copper (Cu and iron (Fe in patients with schizophrenia before (n = 15 and after antipsychotic drug treatment (n = 20 were compared with those of healthy controls (n = 20. Convenient sampling method was used for the selection of subjects. NO was estimated by the use of Griess method, caeruloplasmin was estimated by the use of immunodiffusion method and antioxidant trace metals was estimated by the use of atomic absorption spectrophotometer.
    • RESULTS: The levels of Cu and caeruloplasmin were not significantly different while Fe and Se were significantly reduced in both groups of schizophrenic patients compared with the controls. Zn was significantly elevated in medicated
    • schizophrenics compared with drug-free patients or controls. NO was significantly elevated in drug free patients with schizophrenia compared with controls or treated patients.
    • CONCLUSIONS: Our findings suggest the application of management strategies that will reduce NO but will increase antioxidant trace metals in patients with schizophrenia.
    • KEYWORDS: Schizophrenia, antioxidant defense system, antioxidant status, oxidative Stress.

  5. Enzymatic and chemical oxidation of polygalactomannans from the seeds of a few species of leguminous plants and characterization of the oxidized products.

    Science.gov (United States)

    Merlini, Luca; Boccia, Antonella Caterina; Mendichi, Raniero; Galante, Yves M

    2015-03-20

    Plant polysaccharides are used in a growing number of applications, in their native or in chemically and/or biochemically modified forms. In the present work, we compare TEMPO-mediated oxidation with laccase of polygalactomannans (PGM) from different species of plant leguminous to chemical oxidation with NaClO/NaBr/TEMPO. We have investigated the gums from: locust bean (Ceratonia siliqua), tara (Caesalpinia spinosa), guar (Cyamopsis tetragonolobus), sesbania (Sesbania bispinosa) and fenugreek (Trigonella foenum-graecum). Upon laccase/TEMPO oxidation, PGM viscosity and concentration of reducing groups increased up to five-fold and structured, elastic, stable gels were formed, which could be degraded by hydrolysis with β-mannanase. Conversely, chemical oxidation with NaClO/NaBr/TEMPO caused a rapid, intermediate transition of the gum solutions to compact gels, that immediately reverted to liquid, with a lower viscosity than at the start and an increased concentration of reducing groups, similar to the reaction with laccase. We interpret the above as due to, in the case of laccase, oxidation of primary hydroxyl groups to aldehydes, able to form stable hemiacetalic bonds with free hydroxyl groups. While upon chemical oxidation, primary OH's are only transiently oxidized to aldehydes, followed by rapid oxidation of all carbonyl groups to carboxylates. In either cases, TEMPO appeared to cause a limited splitting of glycosidic bonds of PGM. Native and oxidized PGM were further characterized by 1D and 2D NMR spectroscopy and by rheology. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Antioxidant and enzymatic responses to oxidative stress induced by pre-harvest water supply reduction and ripening on mango (Mangifera indica L. cv. 'Cogshall') in relation to carotenoid content.

    Science.gov (United States)

    Rosalie, Rémy; Joas, Jacques; Deytieux-Belleau, Christelle; Vulcain, Emmanuelle; Payet, Bertrand; Dufossé, Laurent; Léchaudel, Mathieu

    2015-07-20

    The effects of a reduction in water supply during fruit development and postharvest fruit ripening on the oxidative status and the antioxidant defense system were studied in the mango fruit (Mangifera indica L.) cv. Cogshall. Changes in non-enzymatic (ascorbate) and enzymatic (SOD, CAT, APX, MDHAR, DHAR and GR) antioxidants, as well as oxidative parameters (H2O2 and MDA) and major carotenoids, were measured in unripe and ripe fruits from well-irrigated and non-irrigated trees. Under non-limiting water supply conditions, ripening induced oxidation as a result of the production of ROS and decreased ascorbate content. Antioxidant enzymatic systems were activated to protect fruit tissues and to regenerate the ascorbate pool. The carotenoid pool, mainly represented by β-carotene and esterified violaxanthine isomers, accumulated naturally during mango ripening. The suppression of irrigation decreased fruit size and induced accumulation of ABA and of its storage form, ABA-GE, in fruit pulp from the earliest harvest. It also increased oxidation, which was observable by the high levels of ascorbate measured at the early stages at harvest, and by the delay in the time it took to reach the pseudo constant carotene-to-xanthophyll ratio in ripe fruits. Nevertheless, differences between the irrigation treatments on the antioxidant system in ripe fruits were not significant, mainly because of the drastic changes in this system during ripening. Copyright © 2015 Elsevier GmbH. All rights reserved.

  7. Comparison of the properties of cellulose nanocrystals and cellulose nanofibrils isolated from bacteria, tunicate, and wood processed using acid, enzymatic, mechanical, and oxidative methods.

    Science.gov (United States)

    Sacui, Iulia A; Nieuwendaal, Ryan C; Burnett, Daniel J; Stranick, Stephan J; Jorfi, Mehdi; Weder, Christoph; Foster, E Johan; Olsson, Richard T; Gilman, Jeffery W

    2014-05-14

    This work describes the measurement and comparison of several important properties of native cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), such as crystallinity, morphology, aspect ratio, and surface chemistry. Measurement of the fundamental properties of seven different CNCs/CNFs, from raw material sources (bacterial, tunicate, and wood) using typical hydrolysis conditions (acid, enzymatic, mechanical, and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation), was accomplished using a variety of measurement methods. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and 13C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy were used to conclude that CNCs, which are rodlike in appearance, have a higher crystallinity than CNFs, which are fibrillar in appearance. CNC aspect ratio distributions were measured and ranged from 148±147 for tunicate-CNCs to 23±12 for wood-CNCs. Hydrophobic interactions, measured using inverse gas chromatography (IGC), were found to be an important contribution to the total surface energy of both types of cellulose. In all cases, a trace amount of naturally occurring fluorescent compounds was observed after hydrolysis. Confocal and Raman microscopy were used to confirm that the fluorescent species were unique for each cellulose source, and demonstrated that such methods can be useful for monitoring purity during CNC/CNF processing. This study reveals the broad, tunable, multidimensional material space in which CNCs and CNFs exist.

  8. Ternary nanohybrid of reduced graphene oxide-nafion@silver nanoparticles for boosting the sensor performance in non-enzymatic amperometric detection of hydrogen peroxide.

    Science.gov (United States)

    Yusoff, Norazriena; Rameshkumar, Perumal; Mehmood, Muhammad Shahid; Pandikumar, Alagarsamy; Lee, Hing Wah; Huang, Nay Ming

    2017-01-15

    A sensitive and novel electrochemical sensor was developed for the detection of hydrogen peroxide (H 2 O 2 ) using a reduced graphene oxide-nafion@silver6 (rGO-Nf@Ag6) nanohybrid modified glassy carbon electrode (GC/rGO-Nf@Ag6). The GC/rGO-Nf@Ag6 electrode exhibited an excellent electrochemical sensing ability for determining H 2 O 2 with high sensitivity and selectivity. The detection limit of the electrochemical sensor using the GC/rGO-Nf@Ag6 electrode for H 2 O 2 determination was calculated to be 5.35×10 -7 M with sensitivity of 0.4508µAµM -1 . The coupling between rGO-Nf with silver nanoparticles (AgNPs) significantly boosted the electroanalytical performance by providing more active area for analyte interaction, thereby allowing more rapid interfacial electron transfer process. The interfering effect on the current response of H 2 O 2 was studied and the results revealed that the sensor electrode exhibited an excellent immunity from most common interferents. The proposed non-enzymatic electrochemical sensor was used for determining H 2 O 2 in apple juice, and the sensor electrode provided satisfactory results with reliable recovery values. These studies revealed that the novel GC/rGO-Nf@Ag6 sensor electrode could be a potential candidate for the detection of H 2 O 2 . Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Long-term effects of cupric oxide nanoparticles (CuO NPs) on the performance, microbial community and enzymatic activity of activated sludge in a sequencing batch reactor.

    Science.gov (United States)

    Wang, Sen; Li, Zhiwei; Gao, Mengchun; She, Zonglian; Ma, Bingrui; Guo, Liang; Zheng, Dong; Zhao, Yangguo; Jin, Chunji; Wang, Xuejiao; Gao, Feng

    2017-02-01

    The long-term effects of cupric oxide nanoparticles (CuO NPs) on the performance, microbial activity and microbial community of activated sludge were investigated in a sequencing batch reactor (SBR). The SBR performance had no evident change at 0-10 mg/L CuO NPs, whereas the CuO NPs concentration at 30-60 mg/L affected the COD, NH 4 + -N and soluble orthophosphate (SOP) removal, nitrogen and phosphorus removal rate and microbial enzymatic activity of activated sludge. Some CuO NPs might be absorbed on the surface of activated sludge or penetrate the microbial cytomembrane into the microbial cell interior of activated sludge. Compared to 0 mg/L CuO NPs, the reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) release increased by 43.6% and 56.4% at 60 mg/L CuO NPs, respectively. The variations of ROS production and LDH release demonstrated that CuO NPs could induce the toxicity towards the microorganisms and destroy the integrity of microbial cytomembrane in the activated sludge. High throughput sequencing of 16S rDNA indicated that CuO NPs could evidently impact on the microbial richness, diversity and composition of activated sludge in the SBR. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Synthesis and Characterization of Multimetallic Fe(II) and Mn(II ...

    African Journals Online (AJOL)

    MBI

    Synthesis and Characterization of Multimetallic Fe(II) and Mn(II) Using. N4O3 Potentially Heptadentate Ligand. Mustapha, A. and Gani, S. M.. Department of Chemistry, Federal University Dutse, PMB 7156, Jigawa State. Email: abmustapha2004@yahoo.com. ABSTRACT. Potentially heptadentate (N4O3) tripodal Schiff-base ...

  11. Adsorption of Mn(II) and Co(II) ions from aqueous solution using ...

    African Journals Online (AJOL)

    The adsorption of Mn(II) and Co(II) ions from aqueous solution was investigated using batch adsorption experiment at room temperature. The effect of pH, contact time, metal ion concentration and temperature were evaluated. The residual concentrations of the metal ions were determined by atomic absorption ...

  12. Synthesis and Characterization of Multimetallic Fe(II) and Mn(II ...

    African Journals Online (AJOL)

    Iron(II) and Manganese(II) complexes of the resulting ligand were obtained from its reactions with Fe(II) and Mn(II) salts in absolute methanol for the metal to ligand ratio 2:3. These complexes were characterized by Solubility, Conductivity, IR and UV-VIS spectrometry, elemental analysis and mass spectrometry. Keywords: ...

  13. Mn(II), Zn(II) and VO(II) Schiff

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 113; Issue 3. Synthesis and characterisation of Cu(II), Ni(II), Mn(II), Zn(II) and VO(II) Schiff base complexes derived from o-phenylenediamine and acetoacetanilide. N Raman Y Pitchaikani Raja A Kulandaisamy. Inorganic Volume 113 Issue 3 June 2001 pp 183-189 ...

  14. Disposable Non-Enzymatic Glucose Sensors Using Screen-Printed Nickel/Carbon Composites on Indium Tin Oxide Electrodes

    Directory of Open Access Journals (Sweden)

    Won-Yong Jeon

    2015-12-01

    Full Text Available Disposable screen-printed nickel/carbon composites on indium tin oxide (ITO electrodes (DSPNCE were developed for the detection of glucose without enzymes. The DSPNCE were prepared by screen-printing the ITO substrate with a 50 wt% nickel/carbon composite, followed by curing at 400 °C for 30 min. The redox couple of Ni(OH2/NiOOH was deposited on the surface of the electrodes via cyclic voltammetry (CV, scanning from 0–1.5 V for 30 cycles in 0.1 M NaOH solution. The DSPNCE were characterized by field-emission scanning electron microscopy (FE-SEM, X-ray photoelectron spectroscopy (XPS, and electrochemical methods. The resulting electrical currents, measured by CV and chronoamperometry at 0.65 V vs. Ag/AgCl, showed a good linear response with glucose concentrations from 1.0–10 mM. Also, the prepared electrodes showed no interference from common physiologic interferents such as uric acid (UA or ascorbic acid (AA. Therefore, this approach allowed the development of a simple, disposable glucose biosensor.

  15. Disposable Non-Enzymatic Glucose Sensors Using Screen-Printed Nickel/Carbon Composites on Indium Tin Oxide Electrodes.

    Science.gov (United States)

    Jeon, Won-Yong; Choi, Young-Bong; Kim, Hyug-Han

    2015-12-10

    Disposable screen-printed nickel/carbon composites on indium tin oxide (ITO) electrodes (DSPNCE) were developed for the detection of glucose without enzymes. The DSPNCE were prepared by screen-printing the ITO substrate with a 50 wt% nickel/carbon composite, followed by curing at 400 °C for 30 min. The redox couple of Ni(OH)₂/NiOOH was deposited on the surface of the electrodes via cyclic voltammetry (CV), scanning from 0-1.5 V for 30 cycles in 0.1 M NaOH solution. The DSPNCE were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The resulting electrical currents, measured by CV and chronoamperometry at 0.65 V vs. Ag/AgCl, showed a good linear response with glucose concentrations from 1.0-10 mM. Also, the prepared electrodes showed no interference from common physiologic interferents such as uric acid (UA) or ascorbic acid (AA). Therefore, this approach allowed the development of a simple, disposable glucose biosensor.

  16. Non-enzymatic glycosylation of a type I collagen matrix: effects on osteoblastic development and oxidative stress

    Directory of Open Access Journals (Sweden)

    Barrio Daniel A

    2001-08-01

    Full Text Available Abstract Background The tissue accumulation of protein-bound advanced glycation endproducts (AGE may be involved in the etiology of diabetic chronic complications, including osteopenia. The aim of this study was to investigate the effect of an AGE-modified type I collagen substratum on the adhesion, spreading, proliferation and differentiation of rat osteosarcoma UMR106 and mouse non-transformed MC3T3E1 osteoblastic cells. We also studied the role of reactive oxygen species (ROS and nitric oxide synthase (NOS expression on these AGE-collagen mediated effects. Results AGE-collagen decreased the adhesion of UMR106 cells, but had no effect on the attachment of MC3T3E1 cells. In the UMR106 cell line, AGE-collagen also inhibited cellular proliferation, spreading and alkaline phosphatase (ALP activity. In preosteoblastic MC3T3E1 cells (24-hour culture, proliferation and spreading were significantly increased by AGE-collagen. After one week of culture (differentiated MC3T3E1 osteoblasts AGE-collagen inhibited ALP activity, but had no effect on cell number. In mineralizing MC3T3E1 cells (3-week culture AGE-collagen induced a decrease in the number of surviving cells and of extracellular nodules of mineralization, without modifying their ALP activity. Intracellular ROS production, measured after a 48-hour culture, was decreased by AGE-collagen in MC3T3E1 cells, but was increased by AGE-collagen in UMR106 cells. After a 24-hour culture, AGE-collagen increased the expression of endothelial and inducible NOS, in both osteoblastic cell lines. Conclusions These results suggest that the accumulation of AGE on bone extracellular matrix could regulate the proliferation and differentiation of osteoblastic cells. These effects appear to depend on the stage of osteoblastic development, and possibly involve the modulation of NOS expression and intracellular ROS pathways.

  17. Determining the Role of Multicopper Oxidases in Manganese(II) Oxidation by Marine Bacillus Spores

    Science.gov (United States)

    Dick, G. J.; Tebo, B. M.

    2005-12-01

    Bacteria play an important role in the environmental cycling of Mn by oxidizing soluble Mn(II) and forming insoluble Mn(III/IV) oxides. These biogenic Mn oxides are renowned for their strong sorptive and oxidative properties, which control the speciation and availability of many metals and organic compounds. A wide variety of bacteria are known to catalyze the oxidation of Mn(II); one of the most frequently isolated types are Bacillus species that oxidize Mn(II) only as metabolically dormant spores. We are using genetic and biochemical methods to study the molecular mechanisms of this process in these organisms. mnxG, a gene related to the multicopper oxidase (MCO) family of enzymes, is required for Mn(II) oxidation in the model organism, Bacillus sp. strain SG-1. Mn(II)-oxidizing activity can be detected in crude protein extracts of the exosporium and as a discrete band in SDS-PAGE gels, however previous attempts to purify or identify this Mn(II)-oxidizing enzyme have failed. A direct link between the Mn(II)-oxidizing enzyme and the MCO gene suspected to encode it has never been made. We used genetic and biochemical methods to investigate the role of the MCO in the mechanism of Mn(II) oxidation. Comparative analysis of the mnx operon from several diverse Mn(II)-oxidizing Bacillus spores revealed that mnxG is the most highly conserved gene in the operon, and that copper binding sites are highly conserved. As with Mn(II) oxidases from other organisms, heterologous expression of the Bacillus mnxG in E. coli did not yield an active Mn(II) oxidase. Purifying sufficient quantities of the native Mn(II) oxidase from Bacillus species for biochemical characterization has proven difficult because the enzyme does not appear to be abundant, and it is highly insoluble. We were able to partially purify the Mn(II) oxidase, and to analyze the active band by in-gel trypsin digestion followed by tandem mass spectrometry (MS/MS). MS/MS spectra provided a conclusive match to mnx

  18. Manganese oxidation state mediates toxicity in PC12 cells

    International Nuclear Information System (INIS)

    Reaney, S.H.; Smith, D.R.

    2005-01-01

    The role of the manganese (Mn) oxidation state on cellular Mn uptake and toxicity is not well understood. Therefore, undifferentiated PC12 cells were exposed to 0-200 μM Mn(II)-chloride or Mn(III)-pyrophosphate for 24 h, after which cellular manganese levels were measured along with measures of cell viability, function, and cytotoxicity (trypan blue exclusion, medium lactate dehydrogenase (LDH), 8-isoprostanes, cellular ATP, dopamine, serotonin, H-ferritin, transferrin receptor (TfR), Mn-superoxide dismutase (MnSOD), and copper-zinc superoxide dismutase (CuZnSOD) protein levels). Exposures to Mn(III) >10 μM produced 2- to 5-fold higher cellular manganese levels than equimolar exposures to Mn(II). Cell viability and ATP levels both decreased at the highest Mn(II) and Mn(III) exposures (150-200 μM), while Mn(III) exposures produced increases in LDH activity at lower exposures (≥50 μM) than did Mn(II) (200 μM only). Mn(II) reduced cellular dopamine levels more than Mn(III), especially at the highest exposures (50% reduced at 200 μM Mn(II)). In contrast, Mn(III) produced a >70% reduction in cellular serotonin at all exposures compared to Mn(II). Different cellular responses to Mn(II) exposures compared to Mn(III) were also observed for H-ferritin, TfR, and MnSOD protein levels. Notably, these differential effects of Mn(II) versus Mn(III) exposures on cellular toxicity could not simply be accounted for by the different cellular levels of manganese. These results suggest that the oxidation state of manganese exposures plays an important role in mediating manganese cytotoxicity

  19. A combined self-assembly and calcination method for preparation of nanoparticles-assembled cobalt oxide nanosheets using graphene oxide as template and their application for non-enzymatic glucose biosensing.

    Science.gov (United States)

    Zhang, Haiyan; Liu, Sen

    2017-01-01

    Cobalt oxide (Co 3 O 4 )-based materials have been extensively investigated as efficient electrocatalysts for non-enzymatic glucose biosensing. The proper tuning the structure of Co 3 O 4 -based materials could improve sensing performances for glucose detection. Herein, we have developed a combined self-assembly and calcination method to prepare nanoparticles-assembled Co 3 O 4 nanosheets, which exhibit good sensing performances for glucose biosensing. The Co 3 O 4 nanosheets were prepared by the following three steps: (i) the Co 2+ modified graphene oxide (GO) was prepared by the self-assembly of Co 2+ and GO in aqueous solution firstly, and then Co 2+ modified GO film was obtained by vacuum filtration method; (ii) after calcination of Co 2+ modified GO film in N 2 atmosphere, Co 3 O 4 nanoparticles modified reduced GO (RGO) was obtained; (iii) finally, nanoparticles-assembled Co 3 O 4 nanosheets were obtained by calcination of Co 3 O 4 modified RGO in air to remove RGO template. Most importantly, Co 3 O 4 nanosheets exhibit good electrocatalytic activity for oxidation of glucose, leading to high-performance glucose sensor. The detection limit and linear range of Co 3 O 4 nanosheets-based glucose sensor in the present work are 0.15μM, and 1-50μM, respectively. Furthermore, such sensor also shows excellent selectivity for glucose detection, compared to the commonly interfering species including dopamine, and uric acid. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Synthesis, Hirshfeld surface analyses and magnetism of a 1D Mn(II ...

    African Journals Online (AJOL)

    A new Mn-based complex of {[Mn(L)2(mi)]·H2O}n (1) (HL = p-hydroxy phenylacetic acid; mi = 1,1'-(1,4-butanediyl)bis(imidazole)), has been synthesized and structurally characterized. Single-crystal X-ray analyses reveal that compound 1 has a dinuclear Mn(II) unit linking by four carboxylate groups. The bridging N-donor ...

  1. Removal of Mn(II) from the acid mine wastewaters using coal fired bottom ash

    Science.gov (United States)

    Mahidin, M.; Sulaiman, T. N.; Muslim, A.; Gani, A.

    2017-06-01

    Acid mine wastewater (AMW), the wastewater from mining activities which has low pH about 3-5 and contains hazardous heavy metals such as Cu, Fe, Mn, Zn, Pb, etc. Those heavy metals pollution is of prime concern from the environmental view point. Among the heavy metals, Mn occupies the third position in the AMW from one the iron ore mining company in Aceh, Indonesia. In this study, the possibility use of bottom ash from coal fired boiler of steam power plants for the removal of Mn(II) in AMW has been investigated. Experimental has been conducted as follows. Activation of bottom ash was done both by physical and chemical treatments through heating at 270 °C and washing with NaOH activator 0.5 and 1 M. Adsorption test contains two parts observation; preliminary and primary experiments. Preliminary study is addressed to select the best condition of three independent variables i.e.: pH of AMW (3 & 7), bottom ash particle size (40, 60 & 100 mesh) and initial Mn(II) concentrations (100 & 600 mg/l). AMW used was synthetics wastewater. It was found that the best value for NaOH is 1 M, pH is 7, particle size is 100 meshes and initial Mn(II) concentration is 600 mg/l from the adsorption efficiency point of view. The maximum adsorption capacity (q e) is 63.7 mg/g with the efficiency of 85%.

  2. Inhibition of tyrosinase-mediated enzymatic browning by sulfite and natural alternatives

    NARCIS (Netherlands)

    Kuijpers, T.F.M.; Vincken, J.P.

    2013-01-01

    Although sulfite is widely used to counteract enzymatic browning, its mechanism has remained largely unknown. We describe a double inhibitory mechanism of sulfite on enzymatic browning, affecting both the enzymatic oxidation of phenols into o‑quinones, as well as the non‑enzymatic reactions of these

  3. The dependence of the discharge of nitrous oxide by ordinary chernozem steppe of the Central-Chernozem Region of Russia from the content of humus, nitrogen and enzymatic activity

    Science.gov (United States)

    Avksentev, Alexey; Negrobova, Elena; Kramareva, Tatiana; Moiseeva, Evgenya

    2016-04-01

    The dependence of the discharge of nitrous oxide by ordinary chernozem steppe of the Central-Chernozem Region of Russia from the content of humus, nitrogen and enzymatic activity Alexey Avksentev, Elena Negrobova, Tatiana Kramareva, Evgenya Moiseeva 394000 Voronezh, Universitetskaya square, 1 Voronezh State University Nitrous oxide is emitted by soil as a result of microbiological processes, ranks third in the list of aggressive greenhouse gas after carbon dioxide and methane. Nitrous oxide is formed during nitrification and denitrification of ammonia that enters the soil during microbial decomposition of complex organic compounds. Denitrification can be direct and indirect. In the microbiological process of recovery of nitrates involved of the organic substance. In aerobic conditions microorganisms denitrificator behave like normal saprotrophs and oxidize organic matter in the act of breathing oxygen. Thus, they operate at different times two enzyme systems: the electron transport chain with an oxygen acceptor in aerobic and restoration of nitrates under anaerobic conditions. Investigation of the emission of nitrous oxide by ordinary Chernozem steppe of the Central-Chernozem Region showed that it depends on the type of cenosis and the content of available forms of nitrogen. Natural ecosystems emit nitrous oxide more than the soil of arable land. The dependence of the emission of nitrous oxide from the humus content shows positive trend, but the aggregation of data, significant differences are not detected. Research shows that nitrous oxide emissions are seasonal. So the autumn season is characterized by nitrous oxide emissions than spring. Enzymatic processes are an important link in the biological cycle of elements and, consequently, participate in the process of decomposition of organic matter, nitrification and other processes. Analysis of the data on enzyme activity of ordinary Chernozem and the intensity of emission of N20 shows a clear relationship between

  4. EFFECTIVE ALKALINE PEROXIDE OXIDATION PRETREATMENT OF SHEA TREE SAWDUST FOR THE PRODUCTION OF BIOFUELS: KINETICS OF DELIGNIFICATION AND ENZYMATIC CONVERSION TO SUGAR AND SUBSEQUENT PRODUCTION OF ETHANOL BY FERMENTATION USING Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    A. O. Ayeni

    Full Text Available Abstract Shea tree sawdust delignification kinetic data during alkaline peroxide pretreatment were investigated at temperatures of 120 °C, 135 °C, and 150 °C. The activation energy during delignification was 76.4 kJ/mol and the Arrhenius constant was calculated as 8.4 x 106 per min. The reducing sugar yield for the treated to the untreated biomass was about 22-fold. Enzymatic hydrolysis conditions studied were; time (72 h and 96 h, substrate concentration (20, 30, 40, and 50 g/L, and enzyme loadings (10, 25, 40, 50 FPU/g dry biomass, which showed the optimum conditions of 96 h, 40 g/L, and 25 FPU/g dry biomass at 45 °C hydrolysis temperature. At the optimized enzymatic hydrolysis conditions, the reducing sugar yield was 416.32 mg equivalent glucose/g treated dry biomass. After 96 h fermentation of treated biomass, the ethanol obtained at 2% effective cellulose loading was 12.73 g/L. Alkaline peroxide oxidation pretreatment and subsequent enzymatic hydrolysis improved the ethanol yield of the biomass.

  5. The generation of biogenic manganese oxides and its application in the removal of As(III) in groundwater.

    Science.gov (United States)

    Liang, Guannan; Yang, Yu; Wu, Simiao; Jiang, Yonghai; Xu, Yunfeng

    2017-07-01

    The generation of biogenic manganese oxides (BMnOx) by Microbacterium sp. CSA40, and As(III) removal efficiency and mechanism by BMnOx were investigated in this study. The propagation and growth of Microbacterium sp. CSA40 was conducted in half-strength Luria Broth with 10 mg/L Mn(II), then high concentration of Microbacterium sp. CSA40 was added to PYG medium making its OD600 = 0.9 ± 0.05 for BMnOx generation. The initial Mn(II) concentrations, excessively oligotrophic condition, and pH had great influence on generation of BMnOx by Microbacterium sp. CSA40. An appropriate Mn(II) concentration (50 mg/L) was obtained for generation of BMnOx, and higher or lower Mn(II) concentration would interfere Mn(II) oxidization performance. Mn(II) oxidation ability performed best in weak alkaline conditions and would be restricted in an excessively oligotrophic condition. As(III) oxidization and As(V) adsorption proceed simultaneously by BMnOx, what is more, more than 90% of total As was removed by 0.5 g/L BMnOx. During the application process, no Mn(II) was released in the solution, that is, BMnOx retained its ability for Mn(II) oxidization caused by activity of Microbacterium sp. CSA40. Therefore, BMnOx would be a pollution-free, cost-effective, and high-efficiency material for As(III) treatment in groundwater.

  6. Thiol-functionalized polysilsesquioxane as efficient adsorbent for adsorption of Hg(II) and Mn(II) from aqueous solution

    International Nuclear Information System (INIS)

    Niu, Yuzhong; Qu, Rongjun; Liu, Xiguang; Mu, Lei; Bu, Baihui; Sun, Yuting; Chen, Hou; Meng, Yangfeng; Meng, Lina; Cheng, Lin

    2014-01-01

    Highlights: • PMPSQ was promising adsorbent for the removal of Hg(II) and Mn(II). • The adsorption kinetics followed the pseudo-second-order model. • The adsorption isotherms can be described by the monolayer Langmuir model. • The adsorption was controlled by film diffusion and chemical ion-exchange mechanism. - Abstract: Thiol-functionalized polysilsesquioxane was synthesized and used for the adsorption of Hg(II) and Mn(II) from aqueous solution. Results showed that the optimal pH was about 6 and 5 for Hg(II) and Mn(II), respectively. Adsorption kinetics showed that the adsorption equilibriums were established within 100 min and followed pseudo-second-order model. Adsorption isotherms revealed that the adsorption capacities increased with the increasing of temperature. The adsorption was found to be well described by the monolayer Langmuir isotherm model and took place by chemical ion-exchange mechanism. The thermodynamic properties indicated the adsorption processes were spontaneous and endothermic nature. Selectively adsorption showed that PMPSQ can selectively adsorb Hg(II) from binary ion systems in the presence of the coexistent ions Mn(II), Cu(II), Pb(II), Co(II), and Ni(II). Based on the results, it is concluded that PMPSQ had comparable high adsorption efficiency and could be potentially used for the removal of Hg(II) and Mn(II) from aqueous solution

  7. Strategies to inhibit the lipid oxidation in the enzymatic synthesis of monoglycerides by glycerolysis of Babassu oil - doi: 10.4025/actascitechnol.v35i3.14187

    Directory of Open Access Journals (Sweden)

    Larissa Freitas

    2013-06-01

    Full Text Available Different strategies to avoid the lipid feedstock oxidation in the enzymatic synthesis of monoglycerides (MAG from glycerolysis of babassu oil were tested. The reactions were catalyzed by Burkholderia cepacia lipase immobilized on SiO2-PVA and the tests carried out in batchwise. The best strategy was tested in a continuous packed-bed reactor. Different antioxidants and emulsifiers were used, including: Buthyl-hydroxy-toluene (BHT, tocopherol, soy lecithin and Triton X-100. The influence of inert atmosphere (N2 on the MAG production was also investigated. Results were compared with those attaining in the control reaction. The best performance was obtained using N2 in the reaction medium, preventing the oxidation of babassu oil. MAG concentrations were 60 and 24% in batch and continuous mode, respectively. Among the tested antioxidant and emulsifying agents, only soy lecithin was found to be efficient but its application showed limit performance to be used in continuous runs.  

  8. Structural alteration of hexagonal birnessite by aqueous Mn(II): Impacts on Ni(II) sorption

    Energy Technology Data Exchange (ETDEWEB)

    Lefkowitz, Joshua P.; Elzinga, Evert J.

    2017-09-01

    We studied the impacts of aqueous Mn(II) (1 mM) on the sorption of Ni(II) (200 μM) by hexagonal birnessite (0.1 g L- 1) at pH 6.5 and 7.5 with batch experiments and XRD, ATR-FTIR and Ni K-edge EXAFS analyses. In the absence of Mn(II)aq, sorbed Ni(II) was coordinated predominantly as triple corner-sharing complexes at layer vacancies at both pH values. Introduction of Mn(II)aq into Ni(II)-birnessite suspensions at pH 6.5 caused Ni(II) desorption and led to the formation of edge-sharing Ni(II) complexes. This was attributed to competitive displacement of Ni(II) from layer vacancies by either Mn(II) or by Mn(III) formed through interfacial Mn(II)-Mn(IV) comproportionation, and/or incorporation of Ni(II) into the birnessite lattice promoted by Mn(II)-catalyzed recrystallization of the sorbent. Similar to Mn(II)aq, the presence of HEPES or MES caused the formation of edge-sharing Ni(II) sorption complexes in Ni(II)-birnessite suspensions, which was attributed to partial reduction of the sorbent by the buffers. At pH 7.5, interaction with aqueous Mn(II) caused reductive transformation of birnessite into secondary feitknechtite that incorporated Ni(II), enhancing removal of Ni(II) from solution. These results demonstrate that reductive alteration of phyllomanganates may significantly affect the speciation and solubility of Ni(II) in anoxic and suboxic environments.

  9. Characterization of Mn(II) ion binding to the amyloid-β peptide in Alzheimer's disease.

    Science.gov (United States)

    Wallin, Cecilia; Kulkarni, Yashraj S; Abelein, Axel; Jarvet, Jüri; Liao, Qinghua; Strodel, Birgit; Olsson, Lisa; Luo, Jinghui; Abrahams, Jan Pieter; Sholts, Sabrina B; Roos, Per M; Kamerlin, Shina C L; Gräslund, Astrid; Wärmländer, Sebastian K T S

    2016-12-01

    Growing evidence links neurodegenerative diseases to metal exposure. Aberrant metal ion concentrations have been noted in Alzheimer's disease (AD) brains, yet the role of metals in AD pathogenesis remains unresolved. A major factor in AD pathogenesis is considered to be aggregation of and amyloid formation by amyloid-β (Aβ) peptides. Previous studies have shown that Aβ displays specific binding to Cu(II) and Zn(II) ions, and such binding has been shown to modulate Aβ aggregation. Here, we use nuclear magnetic resonance (NMR) spectroscopy to show that Mn(II) ions also bind to the N-terminal part of the Aβ(1-40) peptide, with a weak binding affinity in the milli- to micromolar range. Circular dichroism (CD) spectroscopy, solid state atomic force microscopy (AFM), fluorescence spectroscopy, and molecular modeling suggest that the weak binding of Mn(II) to Aβ may not have a large effect on the peptide's aggregation into amyloid fibrils. However, identification of an additional metal ion displaying Aβ binding reveals more complex AD metal chemistry than has been previously considered in the literature. Copyright © 2016 Elsevier GmbH. All rights reserved.

  10. Synthesis and characterisation of Cu(II), Ni(II), Mn(II), Zn(II) and VO(II ...

    Indian Academy of Sciences (India)

    Unknown

    Synthesis and characterisation of Cu(II), Ni(II), Mn(II), Zn(II) and VO(II) Schiff base complexes derived from o-phenylenediamine and acetoacetanilide. N RAMAN*, Y PITCHAIKANI RAJA and A KULANDAISAMY. Department of Chemistry, VHNSN College, Virudhunagar 626 001, India e-mail: ra_man@123india.com.

  11. Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

    Directory of Open Access Journals (Sweden)

    Verena Weidmann

    2013-10-01

    Full Text Available Allylic oxidations of olefins to enones allow the efficient synthesis of value-added products from simple olefinic precursors like terpenes or terpenoids. Biocatalytic variants have a large potential for industrial applications, particularly in the pharmaceutical and food industry. Herein we report efficient biocatalytic allylic oxidations of spirocyclic terpenoids by a lyophilisate of the edible fungus Pleurotus sapidus. This ‘’mushroom catalysis’’ is operationally simple and allows the conversion of various unsaturated spirocyclic terpenoids. A number of new spirocyclic enones have thus been obtained with good regio- and chemoselectivity and chiral separation protocols for enantiomeric mixtures have been developed. The oxidations follow a radical mechanism and the regioselectivity of the reaction is mainly determined by bond-dissociation energies of the available allylic CH-bonds and steric accessibility of the oxidation site.

  12. Effect of the addition of a cocoa butter-like fat enzymatically produced from olive pomace oil on the oxidative stability of cocoa butter.

    Science.gov (United States)

    Ciftçi, Ozan Nazim; Kowalski, Bolesław; Göğüş, Fahrettin; Fadiloğlu, Sibel

    2009-01-01

    A cocoa butter (CB)-like fat was produced in a packed bed enzyme reactor using sn-1,3 specific lipase, and its blends with CB were prepared at different ratios (CB: CB-like fat; 100: 0, 90: 10, 80: 20, 70: 30, 60: 40, 50: 50, 0: 100). The oxidation kinetics of CB: CB-like fat blends was studied by differential scanning calorimeter (DSC). Samples were heated in DSC at different temperatures (130, 140, 150, 160 degrees C) under 100 mL/min oxygen. From DSC exotherms, oxidation induction times (OIT) were determined and used for the assessment of the oxidative stabilities of the blends. Oxidation kinetics parameters (activation energy, E(a); preexponential factor, Z; and oxidation rate constant, k) were calculated. In general, it has been observed that above 110 degrees C increasing the ratio of CB-like fat in the blend increased the k value with increasing temperature. It has been observed that for all blends the increase in k value with temperature was significant (P < 0.05). Increasing CB-like fat ratio in the blend decreased the content of major TAGs (1,3-dipalmitoyl-2-oleoyl-glycerol [POP]; 1[3]-palmitoyl-3[1]stearoyl-2-oleoyl-glycerol [POS]; 1,3-distearoyl-2-oleoyl-glycerol [SOS]), and decreased the oxidative stability of the blends.

  13. Facile One-Step Microwave-Assisted Route towards Ni Nanospheres/Reduced Graphene Oxide Hybrids for Non-Enzymatic Glucose Sensing

    Directory of Open Access Journals (Sweden)

    Mojiao Zhou

    2012-04-01

    Full Text Available In this work, a facile one-step microwave-assisted method for deposition of monodisperse Ni nanospheres on reduced graphene oxide (rGO sheets to form Ni-rGO nanohybrids is discussed. In the presence of hydrazine monohydrate, Ni nanospheres are grown onto rGO sheets using nickel precursor and GO as starting materials in ethylene glycol (EG solution under a low level of microwave irradiation (300 W for 20 min, during which GO is also reduced to rGO. The as-prepared nanohybrids exhibit well-dispersed Ni nanosphere (about 80 nm in diameter loadings and effective reduction of graphene oxide. The resulting Ni-rGO nanohybrids-modified glassy carbon electrode (GCE shows significantly improved electrochemical performance in nonenzymatic amperometric glucose detection. In addition, interference from the oxidation of common interfering species under physiological conditions, such as ascorbic acid (AA and uric acid (UA, is effectively avoided.

  14. Poly(ethylene oxide monomethyl ether)-block-poly(propylene succinate) nanoparticles. Synthesis and characterization, enzymatic and cellular degradation, micellar solubilization of paclitaxel and in vitro and in vivo evaluation.

    Science.gov (United States)

    Jager, Alessandro; Jäger, Eliézer; Syrová, Zdenka; Mazel, Tomaš; Kováčik, Lubomír; Raška, Ivan; Höcherl, Anita; Kučka, Jan; Konefal, Rafal; Humajova, Jana; Pouckova, Pavla; Stepanek, Petr; Hruby, Martin

    2018-03-30

    Polyester-based nanostructures are widely studied as drug delivery systems due to their biocompatibility and biodegradability. They have already reached the clinical use. In this work we describe a new and simple biodegradable and biocompatible system as alternative to the FDA-approved polyesters (PLGA, PCL and PLA) for the delivery of the anticancer drug paclitaxel (PTX) as a model drug. A hydrophobic polyester, poly(propylene succinate) (PPS) was prepared from a non-toxic alcohol (propylene glycol) and monomer from the Krebs's cycle (succinic acid) in two steps via esterification and melt polycondensation. Further their amphiphilic block copolyester poly(ethylene oxide monomethyl ether)-block-poly(propylene succinate) (mPEO-b-PPS) was prepared by three steps via esterification followed by melt polycondensation and the addition of mPEO to the PPS macromolecules. In vitro cellular behavior of the prepared NPs (enzymatic degradation, uptake, localization and FRET-pair degradation studies) were performed by fluorescence studies from new synthesized Rhodamine B isothiocyanate-poly(propylene succinate) (Rhoda-PPS) and Reactive Blue- poly(propylene succinate) (Blue-PPS) copolymer conjugates. Paclitaxel was loaded to the NPs of variable sizes (30, 70 and 150 nm) and their in vitro release was evaluated in different cell models (Raw 264.7, HeLa, MCF-7 and 4T1 tumor cells) being compared with commercial paclitaxel formulations. The selected 30 nm NPs were chosen for more detailed cytotoxicity in vitro and in vivo tumor efficacy studies. Similarly to the aforementioned copolyesters, the mPEO-b-PPS copolymer present Tg< body temperature enzymatic degradability after uptake into the cells. Detailed cytotoxicity in vitro and in vivo tumor efficacy studies shown the superior efficacy

  15. Binuclear and tetranuclear Mn(II) clusters in coordination polymers derived from semirigid tetracarboxylate and N‑donor ligands: syntheses, new topology structures and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiao-Ling [College of Chemistry and Chemical Engineering, and Henan Key Laboratory of Function-Oriented Porous Materials, Luoyang Normal University, Luoyang 471934 (China); Liu, Guang-Zhen, E-mail: gzliuly@126.com [College of Chemistry and Chemical Engineering, and Henan Key Laboratory of Function-Oriented Porous Materials, Luoyang Normal University, Luoyang 471934 (China); Xin, Ling-Yun [College of Chemistry and Chemical Engineering, and Henan Key Laboratory of Function-Oriented Porous Materials, Luoyang Normal University, Luoyang 471934 (China); Wang, Li-Ya [College of Chemistry and Chemical Engineering, and Henan Key Laboratory of Function-Oriented Porous Materials, Luoyang Normal University, Luoyang 471934 (China); College of Chemistry and Pharmacy Engineering, Nanyang Normal University, Nanyang, Henan 473061 (China)

    2017-02-15

    Two topologically new Mn(II) coordination polymers, namely ([Mn{sub 2}(H{sub 4}ipca)(4,4′-bpy){sub 1.5}(CH{sub 3}CH{sub 2}OH){sub 0.5}(H{sub 2}O){sub 1.5}]·0.5CH{sub 3}CH{sub 2}OH·2.5H{sub 2}O){sub n} (1) and (Mn{sub 4}(H{sub 4}ipca){sub 2}(bze)(H{sub 2}O){sub 4}){sub n} (2) were prepared by the solvothermal reactions of Mn(II) acetate with 5-(2’,3’-dicarboxylphenoxy)isophthalic acid (H{sub 4}ipca) in the presence of different N-donor coligands (4,4′-bpy=4,4′-bipyridyl and bze=1, 4-bis(1-imidazoly)benzene). The single crystal X-ray diffractions reveal that two complexes display 3D metal-organic frameworks with binuclear and tetranuclear Mn(II) units, respectively. Complex 1 features a (3,4,6)-connected porous framework based on dinuclear Mn(II) unit with the (4.5{sup 2}){sub 2}(4{sup 2}.6{sup 8}.8{sup 3}.9{sup 2})(5{sup 2}.8.9{sup 2}.10) new topology, and complex 2 possesses a (3,8)-connected network based on tetranuclear Mn(II) unit with the (4{sup 2}.6){sub 2}(4{sup 4}.6{sup 14}.7{sup 7}.8{sup 2}.9) new topology. Magnetic analyses indicate that both two compounds show weak antiferromagnetic interactions within binuclear and tetranuclear Mn(II) units. - Graphical abstract: Two topologically new Mn(II) metal-organic frameworks with dinuclear and tetranuclear Mn(II) units respectively were assembled by using 5-(2′,3′-Dicarboxylphenoxy)isophthalic acid and N-donor ancillary coligands. Magnetic analysis revealed the existence of dominant antiferromagnetic interactions within the polynuclear Mn(II) units. - Highlights: • Mixed ligand strategy produces two topologically new MOFs with dinuclear and tetranuclear Mn(II) respectively. • Magnetic fitting gives weak antiferromagnetic interactions within the polynuclear Mn(II) units.

  16. Enzymatically Modified Low-Density Lipoprotein Promotes Foam Cell Formation in Smooth Muscle Cells via Macropinocytosis and Enhances Receptor-Mediated Uptake of Oxidized Low-Density Lipoprotein.

    Science.gov (United States)

    Chellan, Bijoy; Reardon, Catherine A; Getz, Godfrey S; Hofmann Bowman, Marion A

    2016-06-01

    Enzyme-modified nonoxidized low-density lipoprotein (ELDL) is present in human atherosclerotic lesions. Our objective is to understand the mechanisms of ELDL uptake and its effects on vascular smooth muscle cells (SMC). Transformation of murine aortic SMCs into foam cells in response to ELDL was analyzed. ELDL, but not acetylated or oxidized LDL, was potent in inducing SMC foam cell formation. Inhibitors of macropinocytosis (LY294002, wortmannin, amiloride) attenuated ELDL uptake. In contrast, inhibitors of receptor-mediated endocytosis (dynasore, sucrose) and inhibitor of caveolae-/lipid raft-mediated endocytosis (filipin) had no effect on ELDL uptake in SMC, suggesting that macropinocytosis is the main mechanism of ELDL uptake by SMC. Receptor for advanced glycation end products (RAGE) is not obligatory for ELDL-induced SMC foam cell formation, but primes SMC for the uptake of oxidized LDL in a RAGE-dependent manner. ELDL increased intracellular reactive oxygen species, cytosolic calcium, and expression of lectin-like oxidized LDL receptor-1 in wild-type SMC but not in RAGE(-/-) SMC. The macropinocytotic uptake of ELDL is regulated predominantly by intracellular calcium because ELDL uptake was completely inhibited by pretreatment with the calcium channel inhibitor lacidipine in wild-type and RAGE(-/-) SMC. This is in contrast to pretreatment with PI3 kinase inhibitors which completely prevented ELDL uptake in RAGE(-/-) SMC, but only partially in wild-type SMC. ELDL is highly potent in inducing foam cells in murine SMC. ELDL endocytosis is mediated by calcium-dependent macropinocytosis. Priming SMC with ELDL enhances the uptake of oxidized LDL. © 2016 American Heart Association, Inc.

  17. Enzymatic recognition of DNA damage induced by UVB-photosensitized titanium dioxide and biological consequences in Saccharomyces cerevisiae: Evidence for oxidatively DNA damage generation

    International Nuclear Information System (INIS)

    Pinto, A. Viviana; Deodato, Elder L.; Cardoso, Janine S.; Oliveira, Eliza F.; Machado, Sergio L.; Toma, Helena K.; Leitao, Alvaro C.; Padula, Marcelo de

    2010-01-01

    Although titanium dioxide (TiO 2 ) has been considered to be biologically inert, finding use in cosmetics, paints and food colorants, recent reports have demonstrated that when TiO 2 is attained by UVA radiation oxidative genotoxic and cytotoxic effects are observed in living cells. However, data concerning TiO 2 -UVB association is poor, even if UVB radiation represents a major environmental carcinogen. Herein, we investigated DNA damage, repair and mutagenesis induced by TiO 2 associated with UVB irradiation in vitro and in vivo using Saccharomyces cerevisiae model. It was found that TiO 2 plus UVB treatment in plasmid pUC18 generated, in addition to cyclobutane pyrimidine dimers (CPDs), specific damage to guanine residues, such as 8-oxo-7,8-dihydroguanine (8-oxoG) and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG), which are characteristic oxidatively generated lesions. In vivo experiments showed that, although the presence of TiO 2 protects yeast cells from UVB cytotoxicity, high mutation frequencies are observed in the wild-type (WT) and in an ogg1 strain (deficient in 8-oxoG and FapyG repair). Indeed, after TiO 2 plus UVB treatment, induced mutagenesis was drastically enhanced in ogg1 cells, indicating that mutagenic DNA lesions are repaired by the Ogg1 protein. This effect could be attenuated by the presence of metallic ion chelators: neocuproine or dipyridyl, which partially block oxidatively generated damage occurring via Fenton reactions. Altogether, the results indicate that TiO 2 plus UVB potentates UVB oxidatively generated damage to DNA, possibly via Fenton reactions involving the production of DNA base damage, such as 8-oxo-7,8-dihydroguanine.

  18. Enzymatic recognition of DNA damage induced by UVB-photosensitized titanium dioxide and biological consequences in Saccharomyces cerevisiae: Evidence for oxidatively DNA damage generation

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, A. Viviana, E-mail: alicia.pinto@incqs.fiocruz.br [Laboratorio de Diagnostico Molecular e Hematologia, Faculdade de Farmacia, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude - Ilha do Fundao, CEP 21941-540, Rio de Janeiro (Brazil); Laboratorio de Radiobiologia Molecular, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude - Ilha do Fundao, CEP 21949-900, Rio de Janeiro (Brazil); Deodato, Elder L. [Laboratorio de Diagnostico Molecular e Hematologia, Faculdade de Farmacia, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude - Ilha do Fundao, CEP 21941-540, Rio de Janeiro (Brazil); Laboratorio de Radiobiologia Molecular, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude - Ilha do Fundao, CEP 21949-900, Rio de Janeiro (Brazil); Cardoso, Janine S. [Laboratorio de Radiobiologia Molecular, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude - Ilha do Fundao, CEP 21949-900, Rio de Janeiro (Brazil); Oliveira, Eliza F.; Machado, Sergio L.; Toma, Helena K. [Laboratorio de Diagnostico Molecular e Hematologia, Faculdade de Farmacia, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude - Ilha do Fundao, CEP 21941-540, Rio de Janeiro (Brazil); Leitao, Alvaro C. [Laboratorio de Radiobiologia Molecular, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude - Ilha do Fundao, CEP 21949-900, Rio de Janeiro (Brazil); Padula, Marcelo de [Laboratorio de Diagnostico Molecular e Hematologia, Faculdade de Farmacia, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude - Ilha do Fundao, CEP 21941-540, Rio de Janeiro (Brazil)

    2010-06-01

    Although titanium dioxide (TiO{sub 2}) has been considered to be biologically inert, finding use in cosmetics, paints and food colorants, recent reports have demonstrated that when TiO{sub 2} is attained by UVA radiation oxidative genotoxic and cytotoxic effects are observed in living cells. However, data concerning TiO{sub 2}-UVB association is poor, even if UVB radiation represents a major environmental carcinogen. Herein, we investigated DNA damage, repair and mutagenesis induced by TiO{sub 2} associated with UVB irradiation in vitro and in vivo using Saccharomyces cerevisiae model. It was found that TiO{sub 2} plus UVB treatment in plasmid pUC18 generated, in addition to cyclobutane pyrimidine dimers (CPDs), specific damage to guanine residues, such as 8-oxo-7,8-dihydroguanine (8-oxoG) and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG), which are characteristic oxidatively generated lesions. In vivo experiments showed that, although the presence of TiO{sub 2} protects yeast cells from UVB cytotoxicity, high mutation frequencies are observed in the wild-type (WT) and in an ogg1 strain (deficient in 8-oxoG and FapyG repair). Indeed, after TiO{sub 2} plus UVB treatment, induced mutagenesis was drastically enhanced in ogg1 cells, indicating that mutagenic DNA lesions are repaired by the Ogg1 protein. This effect could be attenuated by the presence of metallic ion chelators: neocuproine or dipyridyl, which partially block oxidatively generated damage occurring via Fenton reactions. Altogether, the results indicate that TiO{sub 2} plus UVB potentates UVB oxidatively generated damage to DNA, possibly via Fenton reactions involving the production of DNA base damage, such as 8-oxo-7,8-dihydroguanine.

  19. A novel non-enzymatic H{sub 2}O{sub 2} sensor based on polypyrrole nanofibers–silver nanoparticles decorated reduced graphene oxide nano composites

    Energy Technology Data Exchange (ETDEWEB)

    Moozarm Nia, Pooria, E-mail: pooriamn@yahoo.com; Lorestani, Farnaz, E-mail: farnaz.lorestani@siswa.um.edu.my; Meng, Woi Pei, E-mail: pmwoi@um.edu.my; Alias, Y., E-mail: yatimah70@um.edu.my

    2015-03-30

    Graphical abstract: - Highlights: • Decorating silver nanoparticles on the surface of graphene oxide nanocomposites. • Using and comparing two different electrochemical methods for reducing graphene oxide. • Investigating the effect of cyclic voltammetry and amperometry on electropolymerization of polypyrrole nanofibers. • The senor shows superior performances (LOD, LOQ, selectivity, repeatability, reproducibility and stability) towards H{sub 2}O{sub 2}. - Abstract: Graphene oxide (GO) decorated with silver nanoparticles (AgNPs), was electrochemically reduced on glassy carbon electrode (GCE) by an amperometry method (AMP-AgNPs-rGO/GCE). Then, Pyrrole was electropolymerized on the surface of the modified electrode through amperometry process in order to obtain nanofibers of polypyrrole (AMP-PpyNFs-AgNPs-rGO). Fourier-transform infrared transmission spectroscopy and X-ray diffraction approved that during the amperometry process, the GO and Ppy nanofibers were reduced and polymerized respectively and the silver nanoparticles were formed. Field emission scanning electron microscope images indicated that the silver nanoparticles were homogeneously distributed on the rGO surface with a narrow nano size distribution and polypyrrole synthesized in the form of nanofibers with diameter around 100 nm. The first linear section was in the range of 0.1–5 mM with a limit of detection of 1.099 and the second linear section raised to 90 mM with a correlation factor of 0.085 (S/N of 3)

  20. A novel non-enzymatic H2O2 sensor based on polypyrrole nanofibers–silver nanoparticles decorated reduced graphene oxide nano composites

    International Nuclear Information System (INIS)

    Moozarm Nia, Pooria; Lorestani, Farnaz; Meng, Woi Pei; Alias, Y.

    2015-01-01

    Graphical abstract: - Highlights: • Decorating silver nanoparticles on the surface of graphene oxide nanocomposites. • Using and comparing two different electrochemical methods for reducing graphene oxide. • Investigating the effect of cyclic voltammetry and amperometry on electropolymerization of polypyrrole nanofibers. • The senor shows superior performances (LOD, LOQ, selectivity, repeatability, reproducibility and stability) towards H 2 O 2 . - Abstract: Graphene oxide (GO) decorated with silver nanoparticles (AgNPs), was electrochemically reduced on glassy carbon electrode (GCE) by an amperometry method (AMP-AgNPs-rGO/GCE). Then, Pyrrole was electropolymerized on the surface of the modified electrode through amperometry process in order to obtain nanofibers of polypyrrole (AMP-PpyNFs-AgNPs-rGO). Fourier-transform infrared transmission spectroscopy and X-ray diffraction approved that during the amperometry process, the GO and Ppy nanofibers were reduced and polymerized respectively and the silver nanoparticles were formed. Field emission scanning electron microscope images indicated that the silver nanoparticles were homogeneously distributed on the rGO surface with a narrow nano size distribution and polypyrrole synthesized in the form of nanofibers with diameter around 100 nm. The first linear section was in the range of 0.1–5 mM with a limit of detection of 1.099 and the second linear section raised to 90 mM with a correlation factor of 0.085 (S/N of 3)

  1. Photoelectrochemical enzymatic biosensors.

    Science.gov (United States)

    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2017-06-15

    Enzymatic biosensors have been valuable bioanalytical devices for analysis of diverse targets in disease diagnosis, biological and biomedical research, etc. Photoelectrochemical (PEC) bioanalysis is a recently emerged method that promptly becoming a subject of new research interests due to its attractive potential for future bioanalysis with high sensitivity and specificity. PEC enzymatic biosensors integrate the inherent sensitivities of PEC bioanalysis and the selectivity of enzymes and thus share their both advantages. Currently, PEC enzymatic biosensors have become a hot topic of significant research and the recent impetus has grown rapidly as demonstrated by increased research papers. Given the pace of advances in this area, this review will make a thorough discussion and survey on the fundamentals, sensing strategies, applications and the state of the art in PEC enzymatic biosensors, followed by future prospects based on our own opinions. We hope this work could provide an accessible introduction to PEC enzymatic biosensors for any scientist. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Isolated and combined exposure to ammonia and nitrite in giant freshwater pawn (Macrobrachium rosenbergii): effects on the oxidative stress, antioxidant enzymatic activities and apoptosis in haemocytes.

    Science.gov (United States)

    Zhang, Yufan; Ye, Chaoxia; Wang, Anli; Zhu, Xuan; Chen, Changhong; Xian, Jianan; Sun, Zhenzhu

    2015-10-01

    The residual contaminators such as ammonia and nitrite are widely considered as relevant sources of aquatic environmental pollutants, posing a great threat to shrimp survival. To study the toxicological effects of ammonia and nitrite exposure on the innate immune response in invertebrates, we investigated the oxidative stress and apoptosis in haemocytes of freshwater prawn (Macrobrachium rosenbergii) under isolated and combined exposure to ammonia and nitrite in order to provide useful information about adult prawn immune responses. M. rosenbergii (13.44 ± 2.75 g) were exposed to 0, 5, and 25 mg/L total ammonia-N (TAN) and 0, 5, and 20 mg/L nitrite-N for 24 h. All ammonia concentrations were combined with all nitrite concentrations, making a total of nine treatments studied. Following the exposure treatment, antioxidant enzyme activity, reactive oxygen species (ROS) generation, nitric oxide (NO) generation, and apoptotic cell ratio of haemocytes were measured using flow cytometry. Results indicated that ROS generation was sensitive to the combined effect of ammonia and nitrite, which subsequently affected the Cu-Zn SOD activity. In addition, CAT showed the highest activity at 5 mg/L TAN while GPx decreased at 5 mg/L TAN and returned towards baseline at 25 mg/L. NO generation synchronized with the apoptotic cell ratio in haemocytes, indicating that NO production was closely associated with programmed cell death. Both NO production and apoptotic ratios significantly decreased following 25 mg/L TAN, which may be due to the antagonistic regulation of NO and GPx. We hypothesized that the toxicological effect of nitrite exhibited less change in physiological changes compared to that of ammonia, because of the high tolerance to nitrite exposure in mature M. rosenbergii and/or the competitive effects of chloride ions. Taken together, these results showed that ammonia and nitrite caused a series of combined oxidative stress and apoptosis in M. rosenbergi, but further

  3. Oxidative stress and enzymatic scavenging of superoxide radicals induced by solar UV-B radiation in Ulva canopies from southern Spain

    Directory of Open Access Journals (Sweden)

    Kai Bischof

    2003-09-01

    Full Text Available The generation of reactive oxygen species (ROS and scavenging of the superoxide radical by superoxide dismutase (SOD was studied in mat-like canopies of the green macroalga Ulva rotundata Bliding in a tidal brine pond system in southern Spain. Artificial canopies were covered with different cut-off filters, generating different radiation conditions. ROS and SOD were assessed after three days of exposure. ROS induced lipid peroxidation depended on the position of individual thalli within the canopy and on radiation conditions. Samples exposed to the full solar spectrum were most affected, whereas samples either exposed to photosynthetically active radiation (PAR alone or UV radiation without PAR exhibited fewer peroxidation products. The activity of SOD appeared to be controlled by the impinging UV-A and UV-B radiation and also increased in response to oxidative stress. The results provide evidence for additive effects of high PAR and UV-B under field conditions and support the previously proposed hypothesis that UV-B effects are mediated by an inhibition of the xanthophyll cycle, which increases ROS production and, consequently, causes oxidative damage to components of the photosynthetic machinery, such as proteins and pigments.

  4. Physico-chemical properties, oxidative stability and non-enzymatic browning in marine phospholipid emulsions and their use in food applications

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng

    better bioavailability and ability to form liposomes. All these unique properties of marine PL make them an attractive choice as ingredients for food fortification. Nowadays, a wide range of food products fortified with n-3 triglycerides (TAG) are available worldwide. However, the feasibility of using...... marine PL for food fortification has not been explored. The main objective of the present Ph.D. study was to explore the feasibility of using marine PL for food fortification. The secondary objective was to study the physical and oxidative stability of marine PL emulsions while identifying the important...... be prepared by using 2-10 % marine PL. The high physical stability of these emulsions was most likely due to the coexistence of micelles, liposomes and emulsified oil droplets. However, there was a requirement for at least 3 % of marine PL (equivalent to 0.8 - 1.3 % of PC depending on the marine PL sources...

  5. Synthesis, crystal structure and adsorption properties of a novel Mn(II) coordination polymer

    Science.gov (United States)

    Cui, Lian-Sheng; Gan, Yong-Le; Li, Yuan-Cheng; Meng, Jun-Rong

    2017-11-01

    A novel Mn(II) coordination polymer based on a "V"-shaped 1,3-di(4‧-carboxyl-phenyl)benzene acid (H2dpb, dpb = 1,3-di(4‧-carboxyl-phenyl)benzene), namely {[Mn(dpb)(4,4‧-bibp)]·H2O}n (4,4‧-bibp = 4,4‧-bis(imidazol-1-yl)biphenyl) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis (TGA). Furthermore, CO2 and SO2 adsorption properties of the complex were tested by high-pressure adsorption instrument under different pressure. The results show that the adsorption performance of CO2 is far superior to SO2 on the same conditions. The adsorption capacity increases with temperature rising. Very interestingly, the saturated adsorption amount (5.5 mmol/g) at 100 °C is less than the one at 80 °C (7.20 mmol/g). This phenomenon is caused by the escape of water vapor.

  6. Enzymatic synthesis of vanillin

    NARCIS (Netherlands)

    van den Heuvel, RHH; Fraaije, MW; Laane, C; van Berkel, WJH; Heuvel, Robert H.H. van den; Berkel, Willem J.H. van

    Due to increasing interest in natural vanillin, two enzymatic routes for the synthesis of vanillin were developed. The flavoprotein vanillyl alcohol oxidase (VAO) acts on a wide range of phenolic compounds and converts both creosol and vanillylamine to vanillin with high yield. The VAO-mediated

  7. Enzymatic synthesis of vanillin

    NARCIS (Netherlands)

    Heuvel, van den R.H.H.; Fraaije, M.W.; Laane, C.; Berkel, van W.J.H.

    2001-01-01

    Due to increasing interest in natural vanillin, two enzymatic routes for the synthesis of vanillin were developed. The flavoprotein vanillyl alcohol oxidase (VAO) acts on a wide range of phenolic compounds and converts both creosol and vanillylamine to vanillin with high yield. The VAO-mediated

  8. Graphene paper based bioelectrodes for enzymatic biofuel cells

    DEFF Research Database (Denmark)

    Werchmeister, Rebecka Maria Larsen; Shen, Fei; Zhang, Jingdong

    We aim at developing bioelectrodes for enzymatic biofuel cells, where sustainable and renewable enzymes are used for catalyzing the oxidation and reduction of fuel molecules. Here glucose is chosen as fuel molecule and glucose oxidase (GOx) is target enzyme which catalyzes the oxidation of glucose...

  9. A novel non-enzymatic H2O2 sensor based on polypyrrole nanofibers-silver nanoparticles decorated reduced graphene oxide nano composites

    Science.gov (United States)

    Moozarm Nia, Pooria; Lorestani, Farnaz; Meng, Woi Pei; Alias, Y.

    2015-03-01

    Graphene oxide (GO) decorated with silver nanoparticles (AgNPs), was electrochemically reduced on glassy carbon electrode (GCE) by an amperometry method (AMP-AgNPs-rGO/GCE). Then, Pyrrole was electropolymerized on the surface of the modified electrode through amperometry process in order to obtain nanofibers of polypyrrole (AMP-PpyNFs-AgNPs-rGO). Fourier-transform infrared transmission spectroscopy and X-ray diffraction approved that during the amperometry process, the GO and Ppy nanofibers were reduced and polymerized respectively and the silver nanoparticles were formed. Field emission scanning electron microscope images indicated that the silver nanoparticles were homogeneously distributed on the rGO surface with a narrow nano size distribution and polypyrrole synthesized in the form of nanofibers with diameter around 100 nm. The first linear section was in the range of 0.1-5 mM with a limit of detection of 1.099 and the second linear section raised to 90 mM with a correlation factor of 0.085 (S/N of 3)

  10. Novel mode of microbial energy metabolism: organic carbon oxidation coupled to dissimilatory reduction of iron or manganese.

    Science.gov (United States)

    Lovley, D R; Phillips, E J

    1988-06-01

    A dissimilatory Fe(III)- and Mn(IV)-reducing microorganism was isolated from freshwater sediments of the Potomac River, Maryland. The isolate, designated GS-15, grew in defined anaerobic medium with acetate as the sole electron donor and Fe(III), Mn(IV), or nitrate as the sole electron acceptor. GS-15 oxidized acetate to carbon dioxide with the concomitant reduction of amorphic Fe(III) oxide to magnetite (Fe(3)O(4)). When Fe(III) citrate replaced amorphic Fe(III) oxide as the electron acceptor, GS-15 grew faster and reduced all of the added Fe(III) to Fe(II). GS-15 reduced a natural amorphic Fe(III) oxide but did not significantly reduce highly crystalline Fe(III) forms. Fe(III) was reduced optimally at pH 6.7 to 7 and at 30 to 35 degrees C. Ethanol, butyrate, and propionate could also serve as electron donors for Fe(III) reduction. A variety of other organic compounds and hydrogen could not. MnO(2) was completely reduced to Mn(II), which precipitated as rhodochrosite (MnCO(3)). Nitrate was reduced to ammonia. Oxygen could not serve as an electron acceptor, and it inhibited growth with the other electron acceptors. This is the first demonstration that microorganisms can completely oxidize organic compounds with Fe(III) or Mn(IV) as the sole electron acceptor and that oxidation of organic matter coupled to dissimilatory Fe(III) or Mn(IV) reduction can yield energy for microbial growth. GS-15 provides a model for how enzymatically catalyzed reactions can be quantitatively significant mechanisms for the reduction of iron and manganese in anaerobic environments.

  11. Equilibrium, thermodynamic and kinetic studies on biosorption of Mn(II) from aqueous solution by Pseudomonas sp., Staphylococcus xylosus and Blakeslea trispora cells

    International Nuclear Information System (INIS)

    Gialamouidis, D.; Mitrakas, M.; Liakopoulou-Kyriakides, M.

    2010-01-01

    Biosorption of Mn(II) from aqueous solutions using Pseudomonas sp., Staphylococcus xylosus and Blakeslea trispora cells was investigated under various experimental conditions of pH, biomass concentration, contact time and temperature. The optimum pH value was determined to 6.0 and the optimum biomass concentration to 1.0 g L -1 for all types of cells. Mn(II) biosorption was found to fit better to the Langmuir model for Pseudomonas sp. and B. trispora and to Freundlich model for S. xylosus. Langmuir model gave maximum Mn(II) uptake capacity 109 mg g -1 for Pseudomonas sp. and much lower, 59 mg g -1 and 40 mg g -1 for S. xylosus and B. trispora, respectively. Pseudo-second-order kinetic model was also found to be in good agreement with the experimental results. Thermodynamic parameters of the adsorption confirmed the endothermic nature of sorption process with positive heat of enthalpy, accompanied by a positive value of entropy change. Interestingly, desorption experiments by treating biomass with 0.1 M HNO 3 solution resulted to more than 88% recovery of the adsorbed Mn(II) from Pseudomonas sp. and almost 95% and 99% from S. xylosus and B. trispora cells respectively, thus indicating that Mn(II) can be easily and quantitatively recovered from biomass.

  12. Assigning the EPR Fine Structure Parameters of the Mn(II) Centers in Bacillus subtilis Oxalate Decarboxylase by Site-Directed Mutagenesis and DFT/MM Calculations

    Science.gov (United States)

    2015-01-01

    Oxalate decarboxylase (OxDC) catalyzes the Mn-dependent conversion of the oxalate monoanion into CO2 and formate. EPR-based strategies for investigating the catalytic mechanism of decarboxylation are complicated by the difficulty of assigning the signals associated with the two Mn(II) centers located in the N- and C-terminal cupin domains of the enzyme. We now report a mutational strategy that has established the assignment of EPR fine structure parameters to each of these Mn(II) centers at pH 8.5. These experimental findings are also used to assess the performance of a multistep strategy for calculating the zero-field splitting parameters of protein-bound Mn(II) ions. Despite the known sensitivity of calculated D and E values to the computational approach, we demonstrate that good estimates of these parameters can be obtained using cluster models taken from carefully optimized DFT/MM structures. Overall, our results provide new insights into the strengths and limitations of theoretical methods for understanding electronic properties of protein-bound Mn(II) ions, thereby setting the stage for future EPR studies on the electronic properties of the Mn(II) centers in OxDC and site-specific variants. PMID:24444454

  13. Enzymatic glycosylation of lincomycin

    Czech Academy of Sciences Publication Activity Database

    Weignerová, Lenka; Spížek, Jaroslav; Najmanová, Lucie; Křen, Vladimír

    2001-01-01

    Roč. 65, č. 8 (2001), s. 1897-1899 ISSN 0916-8451 R&D Projects: GA ČR GA303/99/1382; GA ČR GA203/01/1018; GA MPO PZ-Z2/23 Institutional research plan: CEZ:AV0Z5020903 Keywords : lincomycin * enzymatic glycosylation * monnosylation Subject RIV: EE - Microbiology, Virology Impact factor: 0.968, year: 2001

  14. Thermoanalytical studies of cimetidine and complexes with Mn(II) Co(II) and Ni(II)

    OpenAIRE

    Ana Carolina Mendes Hacke; Fernanda Moreira; Egon Schnitzler; Neiva Deliberali Rosso

    2014-01-01

    Cimetidine is an important hydrogen histamine receptor and can coordinate metal ions in blood plasma. The stability of cimetidine and its complexes with Mn(II), Co(II) and Ni(II) was evaluated by studies of thermogravimetry (TG) and differential thermal analysis (DTA). Cimetidine was thermally stable up to near 190 °C and above this temperature the thermal decomposition occurred in two stages. Complexes of [Mn(HCm)2]Cl2, [Co(Cm)2]Cl2 and [Ni(Cm)2]Cl2 showed a similar behavior. The pyrolytic d...

  15. LOW-TEMPERATURE OZONE DECOMPOSITION BY COMPLEXES OF Cu(II, Co(II AND Mn(II WITH HEXAMETHYLENETETRAMINE

    Directory of Open Access Journals (Sweden)

    A. S. Truba

    2016-04-01

    Full Text Available First, the complexes MCl2*HTMA*xH2O/SiO2 (M = Cu(II, Co(II, Mn(II with hexa-methylenetetramine (HMTA molecule weakly bound with a central M atom (CM ranging from 5.010-7 to 5.010-6 mol/g have been found to catalyse the ozone decomposition. Their activity and turnover number exceeded much those for MCl2*хН2О/ SiO2 acido complexes

  16. Characterization of manganese oxide precipitates from Appalachian coal mine drainage treatment systems

    International Nuclear Information System (INIS)

    Tan Hui; Zhang Gengxin; Heaney, Peter J.; Webb, Samuel M.; Burgos, William D.

    2010-01-01

    The removal of Mn(II) from coal mine drainage (CMD) by chemical addition/active treatment can significantly increase treatment costs. Passive treatment for Mn removal involves promotion of biological oxidative precipitation of manganese oxides (MnO x ). Manganese(II) removal was studied in three passive treatment systems in western Pennsylvania that differed based on their influent Mn(II) concentrations (20-150 mg/L), system construction (±inoculation with patented Mn(II)-oxidizing bacteria), and bed materials (limestone vs. sandstone). Manganese(II) removal occurred at pH values as low as 5.0 and temperatures as low as 2 deg. C, but was enhanced at circumneutral pH and warmer temperatures. Trace metals such as Zn, Ni and Co were removed effectively, in most cases preferentially, into the MnO x precipitates. Based on synchrotron radiation X-ray diffraction and Mn K-edge extended X-ray absorption fine structure spectroscopy, the predominant Mn oxides at all sites were poorly crystalline hexagonal birnessite, triclinic birnessite and todorokite. The surface morphology of the MnO x precipitates from all sites was coarse and 'sponge-like' composed of nm-sized lathes and thin sheets. Based on scanning electron microscopy (SEM), MnO x precipitates were found in close proximity to both prokaryotic and eukaryotic organisms. The greatest removal efficiency of Mn(II) occurred at the one site with a higher pH in the bed and a higher influent total organic C (TOC) concentration (provided by an upstream wetland). Biological oxidation of Mn(II) driven by heterotrophic activity was most likely the predominant Mn removal mechanism in these systems. Influent water chemistry and Mn(II) oxidation kinetics affected the relative distribution of MnO x mineral assemblages in CMD treatment systems.

  17. The oxidation capacity of Mn3O4 nanoparticles is significantly enhanced by anchoring them onto reduced graphene oxide to facilitate regeneration of surface-associated Mn(III).

    Science.gov (United States)

    Duan, Lin; Wang, Zhongyuan; Hou, Yan; Wang, Zepeng; Gao, Guandao; Chen, Wei; Alvarez, Pedro J J

    2016-10-15

    Metal oxides are often anchored to graphene materials to achieve greater contaminant removal efficiency. To date, the enhanced performance has mainly been attributed to the role of graphene materials as a conductor for electron transfer. Herein, we report a new mechanism via which graphene materials enhance oxidation of organic contaminants by metal oxides. Specifically, Mn3O4-rGO nanocomposites (Mn3O4 nanoparticles anchored to reduced graphene oxide (rGO) nanosheets) enhanced oxidation of 1-naphthylamine (used here as a reaction probe) compared to bare Mn3O4. Spectroscopic analyses (X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy) show that the rGO component of Mn3O4-rGO was further reduced during the oxidation of 1-naphthylamine, although rGO reduction was not the result of direct interaction with 1-naphthylamine. We postulate that rGO improved the oxidation efficiency of anchored Mn3O4 by re-oxidizing Mn(II) formed from the reaction between Mn3O4 and 1-naphthylamine, thereby regenerating the surface-associated oxidant Mn(III). The proposed role of rGO was verified by separate experiments demonstrating its ability to oxidize dissolved Mn(II) to Mn(III), which subsequently can oxidize 1-naphthylamine. The role of dissolved oxygen in re-oxidizing Mn(II) was ruled out by anoxic (N2-purged) control experiments showing similar results as O2-sparged tests. Opposite pH effects on the oxidation efficiency of Mn3O4-rGO versus bare Mn3O4 were also observed, corroborating the proposed mechanism because higher pH facilitates oxidation of surface-associated Mn(II) even though it lowers the oxidation potential of Mn3O4. Overall, these findings may guide the development of novel metal oxide-graphene nanocomposites for contaminant removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Marine Bacillus spores as catalysts for oxidative precipitation and sorption of metals.

    Science.gov (United States)

    Francis, C A; Tebo, B M

    1999-08-01

    The oxidation of soluble manganese(II) to insoluble Mn(III,IV) oxide precipitates plays an important role in the environment. These Mn oxides are known to oxidize numerous organic and inorganic compounds, scavenge a variety of other metals on their highly charged surfaces, and serve as electron acceptors for anaerobic respiration. Although the oxidation of Mn(II) in most environments is believed to be bacterially-mediated, the underlying mechanisms of catalysis are not well understood. In recent years, however, the application of molecular biological approaches has provided new insights into these mechanisms. Genes involved in Mn oxidation were first identified in our model organism, the marine Bacillus sp. strain SG-1, and subsequently have been identified in two other phylogenetically distinct organisms, Leptothrix discophora and Pseudomonas putida. In all three cases, enzymes related to multicopper oxidases appear to be involved, suggesting that copper may play a universal role in Mn(II) oxidation. In addition to catalyzing an environmentally important process, organisms capable of Mn(II) oxidation are potential candidates for the removal, detoxification, and recovery of metals from the environment. The Mn(II)-oxidizing spores of the marine Bacillus sp. strain SG-1 show particular promise, due to their inherent physically tough nature and unique capacity to bind and oxidatively precipitate metals without having to sustain growth.

  19. Enzymatic cascade bioreactor

    Science.gov (United States)

    Simmons, Blake A.; Volponi, Joanne V.; Ingersoll, David; Walker, Andrew

    2007-09-04

    Disclosed is an apparatus and method for continuously converting sucrose to .beta.-D-glucose. The method comprises a three stage enzymatic reactor in which an aqueous solution of sucrose is first converted into a solution of fructose and .alpha.-D-glucose by passing it through a porous, packed column containing an inert media on which invertase is immobilized. This solution is then sent through a second packed column containing glucose isomerase and finally a third packed column containing mutarotase. Solution temperature and pH are adjusted to maximize glucose output.

  20. Relationship between Testosterone, Oxidative Stress Biomarkers ...

    African Journals Online (AJOL)

    Hypogonadism attributable to males with metabolic syndrome was also observed in automechanics occupationally exposed to mixed chemicals accompanied by oxidative stress (OS). We evaluated associations among testosterone, OS biomarkers, enzymatic and non-enzymatic antioxidants in normal weight ...

  1. Enzymatic oxidative dimerization of silymarin flavonolignans

    Czech Academy of Sciences Publication Activity Database

    Gavezzotti, P.; Vavříková, Eva; Valentová, Kateřina; Fronza, G.; Kudanga, T.; Kuzma, Marek; Riva, S.; Biedermann, David; Křen, Vladimír

    2014-01-01

    Roč. 109, NOV 2014 (2014), s. 24-30 ISSN 1381-1177 R&D Projects: GA MŠk(CZ) LD13041; GA ČR(CZ) GP14-14373P Institutional support: RVO:61388971 Keywords : Silybin dimers * Silydianin dimer * Silymarin Subject RIV: CE - Biochemistry Impact factor: 2.128, year: 2014

  2. Equilibrium, thermoanalytical and spectroscopic studies to characterize phytic acid complexes with Mn(II) and Co(II)

    Energy Technology Data Exchange (ETDEWEB)

    Carli, Ligia de; Schnitzler, Egon; Rosso, Neiva Deliberali [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Dept. de Quimica], e-mail: ndrosso@uepg.br; Ionashiro, Massao [Universidade Estadual Paulista (UNESP), Araraquara, SP (Brazil). Inst. de Quimica; Szpoganicz, Bruno [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica

    2009-07-01

    Potentiometric studies were carried out to determine the binding degree of phytic acid with Co(II) and Mn(II) ions, in the absence of dioxygen. Equilibrium constants for all major complexes formed are reported, and the results are presented in the form of distribution diagrams showing the concentrations of individual complexes as a function of pH. The formation constants of the complexes show higher values for the species in which the ligand was more deprotonated. Potentiometric data indicates that the species [MH{sub 4}L]{sup 6-}, was totally formed at pH 7.0 and the complexes were synthesized from this data. A solid state complex of Mn(II) and Co(II) with phytic acid was synthesized. Thermogravimetry, differential scanning calorimetry, and infrared spectroscopy were used to investigate and characterize the thermal behavior of these compounds. The results led to information on the composition, dehydration, thermal stability and thermal decomposition of the isolated complexes. (author)

  3. Modelling Tethered Enzymatic Reactions

    Science.gov (United States)

    Solis Salas, Citlali; Goyette, Jesse; Coker-Gordon, Nicola; Bridge, Marcus; Isaacson, Samuel; Allard, Jun; Maini, Philip; Dushek, Omer

    Enzymatic reactions are key to cell functioning, and whilst much work has been done in protein interaction in cases where diffusion is possible, interactions of tethered proteins are poorly understood. Yet, because of the large role cell membranes play in enzymatic reactions, several reactions may take place where one of the proteins is bound to a fixed point in space. We develop a model to characterize tethered signalling between the phosphatase SHP-1 interacting with a tethered, phosphorylated protein. We compare our model to experimental data obtained using surface plasmon resonance (SPR). We show that a single SPR experiment recovers 5 independent biophysical/biochemical constants. We also compare the results between a three dimensional model and a two dimensional model. The work gives the opportunity to use known techniques to learn more about signalling processes, and new insights into how enzyme tethering alters cellular signalling. With support from the Mexican Council for Science and Technology (CONACyT), the Public Education Secretariat (SEP), and the Mexican National Autonomous University's Foundation (Fundacion UNAM).

  4. Scanning tunneling microscopy investigation of nano-structured α-K5PW11(M x OH2)O39(M = Mn(II), Co(II), Ni(II), and Zn(II)) Keggin heteropolyacid catalyst monolayers.

    Science.gov (United States)

    Choi, Jung Ho; Kang, Tae Hun; Bang, Yongju; Yoo, Jaekyeong; Jun, Jin Oh; Song, In Kyu

    2014-11-01

    Nano-structured α-K5PW11(M x OH2)O39 (M = Mn(II), Co(II), Ni(II), and Zn(II)) Keggin heteropolyacids (HPAs) were investigated by scanning tunneling microscopy (STM) and tunneling spectroscopy (TS) measurements in order to elucidate their redox property and oxidation catalysis. HPA molecules formed two-dimensional self-assembled monolayer arrays on highly oriented pyrolytic graphite (HOPG) surface. Furthermore, HPAs exhibited a distinctive current-voltage behavior referred to as negative differential resistance (NDR) phenomenon. The measured NDR peak voltage of HPAs was correlated with the reduction potential and the absorption edge energy determined by electrochemical method and UV-visible spectroscopy, respectively. NDR peak voltage of HPAs appeared at less negative voltage with increasing reduction potential and with decreasing UV-visible absorption edge energy. The correlations strongly suggested that NDR phenomenon was closely related to the redox property of HPAs. Vapor-phase oxidation of benzyl alcohol to benzaldehyde was carried out as a model reaction to track the oxidation catalysis of HPAs. NDR peak voltage appeared at less negative voltage with increasing yield for benzaldehyde.

  5. Enzymatic desulfurization of coal

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Y.N.; Crooker, S.C.; Kitchell, J.P.; Nochur, S.V. (DynaGen, Inc., Cambridge, MA (United States)); Marquis, J.K. (Boston Univ., MA (United States). School of Medicine)

    1989-11-07

    Our experimental approach focuses on the use of enzymes which catalyze the addition of oxygen to organic compounds. In tailoring the application of these enzymes to coal processing, we are particularly interested in ensuring that oxidation occurs at sulfur and not at carbon-carbon bonds. Previous studies with DBT have shown that the reaction most frequently observed in microbial oxidative pathways is one in which DBT is oxidized at ring carbons. These reactions, as we have said, are accompanied by a considerable decrease in the energy content of the compound. In addition, microbial pathways have been identified in which the sulfur atom is sequentially oxidized to sulfoxide, to sulfone, to sulfonate, and finally to sulfuric acid. In this case, the fuel value of the desulfurized compounds is largely retained. We are evaluating the potential of commercially available enzymes to selectively catalyze oxidation at sulfur.

  6. THE INFLUENCE OF pH TOWARDS MULTIPLE METAL ION ADSORPTION OF Cu(II, Zn(II, Mn(II, AND Fe(II ON HUMIC ACID

    Directory of Open Access Journals (Sweden)

    Buhani Buhani

    2010-06-01

    Full Text Available Multiple metal ions adsorption of Cu(II, Zn(II, Mn(II and Fe(II on humic acid with a batch method has been carried out at pH interaction of 3, 5, and 6. Concentration of metal ions in solution before and after interaction was analyzed with Atomic Absorption Spectrophotometer (AAS. Result showed that adsorption multiple metal ions of Cu(II, Zn(II, Mn(II, and Fe(II on humic acid is optimum at pH 5. Adsorption energies of the multiple metal ions Cu(II, Zn(II, Mn(II, and Fe(II on humic acid at pH 3, 5, and 6 are around 35.0 - 37.6 kJ/mole. In general, capacity of competition adsorption of the multiple metal ions has an order as follows; Cu(II < Fe(II < Zn(II < Mn(II.   Keywords: Humic acid, adsorption, multiple metal

  7. Enzymatic modification of starch

    DEFF Research Database (Denmark)

    Jensen, Susanne Langgård

    In the food industry approaches for using bioengineering are investigated as alternatives to conventional chemical and physical starch modification techniques in development of starches with specific properties. Enzyme-assisted post-harvest modification is an interesting approach to this, since...... it is considered a clean and energy saving technology. This thesis aimed to investigate the effect of using reaction conditions, simulating an industrial process, for enzymatic treatment of starch with branching enzyme (BE) from Rhodothermus obamensis. Thus treatements were conducted at 70°C using very high...... substrate concentration (30-40% dry matter (DM)) and high enzyme activity (750-2250 BE units (BEU)/g sample). Starches from various botanical sources, representing a broad range of properties, were used as substrates. The effects of the used conditions on the BE-reaction were evaluated by characterization...

  8. Enzymatic modification of starch

    DEFF Research Database (Denmark)

    Jensen, Susanne Langgård

    In the food industry approaches for using bioengineering are investigated as alternatives to conventional chemical and physical starch modification techniques in development of starches with specific properties. Enzyme-assisted post-harvest modification is an interesting approach to this, since...... it is considered a clean and energy saving technology. This thesis aimed to investigate the effect of using reaction conditions, simulating an industrial process, for enzymatic treatment of starch with branching enzyme (BE) from Rhodothermus obamensis. Thus treatements were conducted at 70°C using very high...... of the obtained products and were correlated to properties of the starch substrates. It was found that the obtained products differed depending on both the conditions used and the properties of the starch. Products of starch from certain origins completely lost their granular structure during the enzyme treatment...

  9. Enzymatic Modification of Sphingomyelin

    DEFF Research Database (Denmark)

    Zhang, Long; Hellgren, Lars; Xu, Xuebing

    2005-01-01

    . Due to its major role in the water-retaining properties of the epidermis, ceramide is of great commercial potential in cosmetic and pharmaceuticals such as hair and skin care products. In current, ceramide is not easy to synthesis for industrial application and synthetic ceramide is still expensive......Sphingomyelin (SM) is a ubiquitous component of animal cell membranes, and it is the most abundant sphingolipid. Ceramide, a hydrolysis product from SM, has an important role in cellular signaling, and especially in the regulation of apoptosis, cell differentiation, transformation and proliferation....... Therefore, it is desirable to develop alternative cost-efficient, high yield production methods. This study optimized the enzymatic production of ceramide from SM. Phospholipase C from Clostridium perfringens was chosen to catalyze the reaction. Several important factors were considered in optimization....

  10. Enzymatic Modification of Sphingomyelin

    DEFF Research Database (Denmark)

    Due to its major role in maintaining the water-retaining properties of the epidermis, ceramide is of great commercial potential in cosmetic and pharmaceuticals such as hair and skin care products. Currently, chemical synthesis of ceramide is a costly process, and developments of alternative cost......-efficient, high yield production methods are of great interest. In the present study, the potential of producing ceramide through the enzymatic hydrolysis of sphingomyelin have been studied. sphingomyelin is a ubiquitous membrane-lipid and rich in dairy products or by-products. It has been verified...... that sphingomyelin modification gives a feasible approach to the potential production of ceramide. The reaction system has been improved through system evaluation and the optimization of several important factors, and phospholipase C from Clostridium perfringens shows higher activity towards the hydrolysis reaction...

  11. Enzymatic desulfurization of coal

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Y.N.; Crooker, S.C.; Kitchell, J.P.; Nochur, S.V.

    1989-12-14

    Our experimental approach focuses on the use of enzymes which catalyze the addition of oxygen to organic compounds., In tailoring the application of these enzymes to coal processing, we are particularly interested in ensuring that oxidation occurs at sulfur and not at carbon-carbon bonds. Previous studies with DBT have shown that the reaction most frequently observed in microbial oxidative pathways is one in which DBT is oxidized at ring carbons. These reactions, as we have said, are accompanied by a considerable decrease in the energy content of the compound. In addition, microbial pathways have been identified in which the sulfur atom is sequentially oxidized to sulfoxide, to sulfone, to sulfonate, and finally to sulfuric acid. In this case, the fuel value of the desulfurized compounds is largely retained. We are evaluating the potential of commercially available enzymes to perform this function.

  12. Application of Local Adsorbant From Southeast Sulawesi Clay Immobilized Saccharomyces Cerevisiae Bread’s Yeast Biomass for Adsorption Of Mn(Ii) Metal Ion

    Science.gov (United States)

    R, Halimahtussaddiyah; Mashuni; Budiarni

    2017-05-01

    Southeast Sulawesi has a great stock of clay. It is probably to use as a source of adsorbent. The adsorbent capacity of clay can be largered with teratment using bread’s yeast as biomass. At this research, study of analysis adsorption of Mn(II) metal ion on clay immobilized Saccharomyces cerevisiae bread’s yeast biomass adsorbent has been conducted. The aims of this research were to determine the effects of contact time, pH and concentration of Mn(II) metal ion and to determine the adsorption capacity of clay immobilized S. cerevisiae biomass for adsorbtion of Mn(II) metal ion. Activated clay was synthesized by reaction of clay with KMnO4, H2SO4 and HCl. S. cerevisiae biomass was result by bread’s yeast mashed. Immobilization of S. cerevisiae biomass into clay was done by mixing of ratio of S. cerevisiae bread’s yeast biomass and clay equal to 1:3 (mass of biomassa : mass of clay). The adsorption capacity was determined by using Freundlich and Langmuir adsorption isoterms. The results of FTIR spectrums showed that the functional groups of clay immobilized S. cerevisiae biomass were Si-OH (wave number 1643 cm-1), Si-O-Si (wave number 1033 cm-1), N-H (wave number 2337 cm-1), O-H (wave number 3441cm-1), and C-H (wave number 2931 cm-1). The result of adsorption capacity from Mn(II) metal ion of contact time optimum 120 minutes, pH optimun at 7 and concentration optimum 50 mg/L were 1,816 mg/g; 0,509 mg/g and 2,624mg/g respectively. The adsorption capacity of Mn(II) metal ion with ratio 1:3 (biomass : clay) was 0,1045 mg/g. Type of isothermal adsorption followed the Freunlich adsorption.

  13. Metal Inhibition of Growth and Manganese Oxidation in Pseudomonas putida GB-1

    Science.gov (United States)

    Pena, J.; Sposito, G.

    2009-12-01

    Biogenic manganese oxides (MnO2) are ubiquitous nanoparticulate minerals that contribute to the adsorption of nutrient and toxicant metals, the oxidative degradation of various organic compounds, and the respiration of metal-reducing bacteria in aquatic and terrestrial environments. The formation of these minerals is catalyzed by a diverse and widely-distributed group of bacteria and fungi, often through the enzymatic oxidation of aqueous Mn(II) to Mn(IV). In metal-impacted ecosystems, toxicant metals may alter the viability and metabolic activity of Mn-oxidizing organisms, thereby limiting the conditions under which biogenic MnO2 can form and diminishing their potential as adsorbent materials. Pseudomonas putida GB-1 (P. putida GB-1) is a model Mn-oxidizing laboratory culture representative of freshwater and soil biofilm-forming bacteria. Manganese oxidation in P. putida GB-1 occurs via two single-electron-transfer reactions, involving a multicopper oxidase enzyme found on the bacterial outer membrane surface. Near the onset of the stationary phase of growth, dark brown MnO2 particles are deposited in a matrix of bacterial cells and extracellular polymeric substances, thus forming heterogeneous biomineral assemblages. In this study, we assessed the influence of various transition metals on microbial growth and manganese oxidation capacity in a P. putida GB-1 culture propagated in a nutrient-rich growth medium. The concentration-response behavior of actively growing P. putida GB-1 cells was investigated for Fe, Co, Ni, Cu and Zn at pH ≈ 6 in the presence and absence of 1 mM Mn. Toxicity parameters such as EC0, EC50 and Hillslope, and EC100 were obtained from the sigmoidal concentration-response curves. The extent of MnO2 formation in the presence of the various metal cations was documented 24, 50, 74 and 104 h after the metal-amended medium was inoculated. Toxicity values were compared to twelve physicochemical properties of the metals tested. Significant

  14. Pretreatment of sugarcane bagasse using the advanced oxidation process by electron beam for enzymatic hydrolysis of cellulose; Pre-tratamento do bagaco de cana utilizando o processo de oxidacao avancada por feixe de eletrons para hidrolise enzimatica da celulose

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Marcia Almeida

    2013-07-01

    The sugar cane bagasse is a renewable energy source and a raw material promise in the biofuel production, once represents about 30% of glucose contained in the plant with the potential to be hydrolyzed and then converted to ethanol. The bagasse is composed of cellulose, straight chain of glucose, of hemicellulose, an amorphous polymer consisting of xylose, arabinose, galactose, and mannose, and of lignin, a complex polymer consisting of fenilpropan units that acts as waterproof coating on the fibers, which is hard to remove due its recalcitrant nature. The aim of this work was to study the electron beam processing as a pretreatment of sugarcane bagasse to enzymatic hydrolysis of cellulose. The pretreatment of sugarcane bagasse is one of the most important steps to make this material economically viable and competitive on the energy production. As a pretreatment the electron beam processing can weak the hemicellulose and lignin structures by the action highly reactive radicals that breaks the links, reducing the degree of polymerization fibers. It was evaluated the chemical and structural modifications on fibers caused by the irradiation, the enzymatic hydrolysis of electron beam as the only pretreatment and combined to steam explosion. For enzymatic hydrolysis it was used the commercial enzymes from Novozymes. The radiation processing promotes changes in structure and composition of sugarcane bagasse, increasing the solubility, that is related to hemicellulose and cellulose cleavage, and also increasing the enzymatic conversion yield. In the case of exploded bagasse there is no changes in the enzymatic hydrolysis yield, however the electron beam processing promoted a 67% reduction of furfural, that is formed in the steam explosion process. (author)

  15. Synthesis, characterization and cytotoxicity of mixed ligand Mn(II, Co(II and Ni(II complexes

    Directory of Open Access Journals (Sweden)

    Osman Souad A.

    2014-01-01

    Full Text Available Complexes of the type [ML'L(OH(H2O] {where M= Ni(II, Co(II or Mn(II, L'= isatin and HL= 3-(2-phenylhydrazonoacetylacetone, 3-(2-(4-chlorophenylhydrazonoacetylacetone or 3-(2-(4-bromophenylhydrazono-acetylacetone} have been synthesized by equimolar reaction of a metal(II chloride with isatin and 3-(2-(arylhydrazonoacetylacetone. The resulting complexes have been characterized by elemental analyses, molar conductivity, spectral data (IR, 1H NMR, mass and magnetic moments. Furthermore, the ligands and their metal complexes have been screened for their cytotoxicity against different human cancer cell lines by using SRB assay. The results showed that most of the mixed ligand metal complexes have high cytotoxicity in comparison with the reference drugs used.

  16. Chelating Schiff base assisted azide-bridged Mn(II), Ni(II) and Cu(II) magnetic coordination polymers.

    Science.gov (United States)

    Bai, Shi-Qiang; Fang, Chen-Jie; He, Zheng; Gao, En-Qing; Yan, Chun-Hua; Hor, T S Andy

    2012-11-21

    Four new Mn(II), Ni(II) and Cu(II) coordination polymers [Mn2(L1)(μ(1,1)-N3)2(μ(1,3)-N3)2]n (1), [Ni(L2)2(μ(1,3)-N3)]n(ClO4)n (2), [Cu(L3)(μ(1,1)-N3)(N3)]n (3) and [Cu(L4)(μ(1,1)-N3)2]n (4) (L1 = N,N′-bis(2-pyridylmethylene)ethane-1,2-diamine, L2 = N-(2-pyridylmethylene)methylamine, L3 = N-(2-pyridylmethylene)-3-pyridylamine, L4 = N-(2-pyridylmethylene)-tbutylamine) have been synthesized and characterized by single-crystal X-ray analysis and magnetic measurements. Complex 1 indicates a stoichiometry-dependent structural change (based on Mn:L1:N3 = 2:1:4 molar ratio) and consists of two-dimensional (2-D) (4,4) net layers, in which Mn(II) centers are co-bridged by single end-to-end (EE), double end-on (EO) azide and chelate-bridging L1 ligands. Complex 2 shows a single EE azide-bridged one-dimensional (1-D) Ni(II) chain. Complexes 3 and 4 indicate single EO and double EO azide-bridged 1-D Cu(II) chains, respectively. Complex 1 exhibits weak ferromagnetism due to its intra-layer spin-canting with T(c) = 20 K. Complex 2 shows an unusual intra-chain ferromagnetic coupling and spin-canting behaviour. Both complexes 3 and 4 exhibit intra-chain antiferromagnetic interactions. Magneto-structural parameters for these related complexes were also discussed.

  17. Electrochemical non-enzymatic glucose sensors

    International Nuclear Information System (INIS)

    Park, Sejin; Boo, Hankil; Chung, Taek Dong

    2006-01-01

    The electrochemical determination of glucose concentration without using enzyme is one of the dreams that many researchers have been trying to make come true. As new materials have been reported and more knowledge on detailed mechanism of glucose oxidation has been unveiled, the non-enzymatic glucose sensor keeps coming closer to practical applications. Recent reports strongly imply that this progress will be accelerated in 'nanoera'. This article reviews the history of unraveling the mechanism of direct electrochemical oxidation of glucose and making attempts to develop successful electrochemical glucose sensors. The electrochemical oxidation of glucose molecules involves complex processes of adsorption, electron transfer, and subsequent chemical rearrangement, which are combined with the surface reactions on the metal surfaces. The information about the direct oxidation of glucose on solid-state surfaces as well as new electrode materials will lead us to possible breakthroughs in designing the enzymeless glucose sensing devices that realize innovative and powerful detection. An example of those is to introduce nanoporous platinum as an electrode, on which glucose is oxidized electrochemically with remarkable sensitivity and selectivity. Better model of such glucose sensors is sought by summarizing and revisiting the previous reports on the electrochemistry of glucose itself and new electrode materials

  18. Enzymatic network for production of ether amines from alcohols

    DEFF Research Database (Denmark)

    Palacio, Cyntia M.; Crismaru, Ciprian G.; Bartsch, Sebastian

    2016-01-01

    We constructed an enzymatic network composed of three different enzymes for the synthesis of valuable ether amines. The enzymatic reactions are interconnected to catalyze the oxidation and subsequent transamination of the substrate and to provide cofactor recycling. This allows production...... for reactions containing 10mM alcohol and up to 280mM ammonia corresponded well to predicted conversions. The results indicate that efficient amination can be driven by high concentrations of ammonia and may require improving enzyme robustness for scale-up....

  19. Reactivity of biogenic manganese oxide for metal sequestration and photochemistry: Computational solid state physics study

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, K.D.; Sposito, G.

    2010-02-01

    Many microbes, including both bacteria and fungi, produce manganese (Mn) oxides by oxidizing soluble Mn(II) to form insoluble Mn(IV) oxide minerals, a kinetically much faster process than abiotic oxidation. These biogenic Mn oxides drive the Mn cycle, coupling it with diverse biogeochemical cycles and determining the bioavailability of environmental contaminants, mainly through strong adsorption and redox reactions. This mini review introduces recent findings based on quantum mechanical density functional theory that reveal the detailed mechanisms of toxic metal adsorption at Mn oxide surfaces and the remarkable role of Mn vacancies in the photochemistry of these minerals.

  20. Homogeneous, Heterogeneous, and Enzymatic Catalysis.

    Science.gov (United States)

    Oyama, S. Ted; Somorjai, Gabor A.

    1988-01-01

    Discusses three areas of catalysis: homegeneous, heterogeneous, and enzymatic. Explains fundamentals and economic impact of catalysis. Lists and discusses common industrial catalysts. Provides a list of 107 references. (MVL)

  1. Mechanism of Alkene, Alkane, and Alcohol Oxidation with H2O2 by an in Situ Prepared Mn-II/Pyridine-2-carboxylic Acid Catalyst

    NARCIS (Netherlands)

    Saisaha, Pattama; Dong, Jia Jia; Meinds, Tim G.; de Boer, Johannes W.; Hage, Ronald; Mecozzi, Francesco; Kasper, Johann B.; Browne, Wesley R.

    The oxidation of alkenes, alkanes, and alcohols with H2O2 is catalyzed efficiently using an in situ prepared catalyst comprised of a MnII salt and pyridine-2-carboxylic acid (PCA) together with a ketone in a wide range of solvents. The mechanism by which these reactions proceed is elucidated, with a

  2. Influence of magnetic field on enzymatic ONOO- production

    Science.gov (United States)

    Dranova, T.; Petrovskii, D.; Ershov, N.; Slepneva, I.; Stass, D.

    2017-08-01

    Enzymatic oxidation of L-arginine catalyzed by inducible nitric oxide synthase gives nitric oxide as the main product and superoxide anion as a side reaction product. Recombination of these radicals gives a very reactive species - peroxynitrite, which is involved in many biochemical processes. In the current work it was shown that such a system can be a usable model system for investigating the influence of magnetic field on enzymatic peroxynitrite formation. Using a selective fluorescent probe for peroxynitrite - coumarin boronic acid and an adopted for the experimental purpose incubation mixture, magnetic field experiments have been done at 11.7T. The averaged magnetic field effect is equal to 2.8±0.9%.

  3. Cation Effects on the Layer Structure of Biogenic Mn-Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, M.; Ginder-Vogel, M; Parikh, S; Feng, X; Sparks, D

    2010-01-01

    Biologically catalyzed Mn(II) oxidation produces biogenic Mn-oxides (BioMnO{sub x}) and may serve as one of the major formation pathways for layered Mn-oxides in soils and sediments. The structure of Mn octahedral layers in layered Mn-oxides controls its metal sequestration properties, photochemistry, oxidizing ability, and topotactic transformation to tunneled structures. This study investigates the impacts of cations (H{sup +}, Ni(II), Na{sup +}, and Ca{sup 2+}) during biotic Mn(II) oxidation on the structure of Mn octahedral layers of BioMnO{sub x} using solution chemistry and synchrotron X-ray techniques. Results demonstrate that Mn octahedral layer symmetry and composition are sensitive to previous cations during BioMnO{sub x} formation. Specifically, H{sup +} and Ni(II) enhance vacant site formation, whereas Na{sup +} and Ca{sup 2+} favor formation of Mn(III) and its ordered distribution in Mn octahedral layers. This study emphasizes the importance of the abiotic reaction between Mn(II) and BioMnO{sub x} and dependence of the crystal structure of BioMnO{sub x} on solution chemistry.

  4. Synthesis, molecular structure, biological properties and molecular docking studies on Mn(II), Co(II) and Zn(II) complexes containing bipyridine-azide ligands.

    Science.gov (United States)

    Thamilarasan, Vijayan; Jayamani, Arumugam; Sengottuvelan, Nallathambi

    2015-01-07

    Metal complexes of the type Mn(bpy)2(N3)2 (1), Co(bpy)2(N3)2·3H2O (2) and Zn2(bpy)2(N3)4 (3) (Where bpy = 2,2-bipyridine) have been synthesized and characterized by elemental analysis and spectral (FT-IR, UV-vis) studies. The structure of complexes (1-3) have been determined by single crystal X-ray diffraction studies and the configuration of ligand-coordinated metal(II) ion was well described as distorted octahedral coordination geometry for Mn(II), Co(II) and distorted square pyramidal geometry for Zn(II) complexes. DNA binding interaction of these complexes (1-3) were investigated by UV-vis absorption, fluorescence circular dichroism spectral and molecular docking studies. The intrinsic binding constants Kb of complexes 1, 2 and 3 with CT-DNA obtained from UV-vis absorption studies were 8.37 × 10(4), 2.23 × 10(5) and 5.52 × 10(4) M(-1) respectively. The results indicated that the three complexes are able to bind to DNA with different binding affinity, in the order 2 > 1 > 3. Complexes (1-3) exhibit a good binding propensity to bovine serum albumin (BSA) proteins having relatively high binding constant values. Gel electrophoresis assay demonstrated the ability of the complexes 1-3 promote the cleavage ability of the pBR322 plasmid DNA in the presence of the reducing agent 3-mercaptopropionic acid (MPA) but with different cleavage mechanisms: the complex 3 cleaves DNA via hydrolytic pathway (T4 DNA ligase assay), while the DNA cleavage by complexes 1 and 2 follows oxidative pathway. The chemical nuclease activity follows the order: 2 > 1 > 3. The effects of various activators were also investigated and the nuclease activity efficacy followed the order MPA > GSH > H2O2 > Asc. The cytotoxicity studies of complexes 1-3 were tested in vitro on breast cancer cell line (MCF-7) and they found to be active. Copyright © 2014. Published by Elsevier Masson SAS.

  5. Characterizing Enzymatic Deposition for Microelectrode Neurotransmitter Detection

    Energy Technology Data Exchange (ETDEWEB)

    Hosein, W. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Yorita, A. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tolosa, V. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-08-12

    The enzyme immobilization process, one step in creating an enzymatic biosensor, was characterized and analyzed as a function of its physical properties. The neural glutamic biosensor is a flexible device, effectively minimizing trauma to the area of implantation. The Multielectrode Array (MEA) is composed primarily of a proprietary polymer which has been successfully implanted into human subjects in recent years. This polymer allows the device the pliability that other devices normally lack, though this poses some challenges to implantation. The electrodes are made of Platinum (Pt), and can range in number from eight to thirty two electrodes per device. These electrodes are electroplated with a semipermeable polymer layer to improve selectivity of the electrode to the neurotransmitter of interest, in this case glutamate. A signal is created from the interaction of glutamate in the brain with the glutamate oxidase (GluOx) which is immobilized on the surface of the electrode by using crosslinking chemistry in conjunction with glutaraldehyde and Bovine Serum Albumin (BSA). The glutamate is oxidized by glutamate oxidase, producing α-ketoglutarate and hydrogen peroxide (H2O2) as a by-product. The production of H2O2 is crucial for detection of the presence of the glutamate within the enzymatic coating, as it diffuses through the enzyme layer and oxidizes at the surface of the electrode. This oxidation is detectable by measurable change in the current using amperometry. Hence, the MEA allows for in vivo monitoring of neurotransmitter activity in real time. The sensitivity of the sensor to these neurotransmitters is dependent on the thickness of the layer, which is investigated in these experiments in order to optimize the efficacy of the device to detecting the substrate, once implanted.

  6. Magnetic, thermal and spectroscopic properties of 5-chloro-2-methoxybenzoates of Mn(II, Co(II, Ni(II, Cu(II and Zn(II

    Directory of Open Access Journals (Sweden)

    BEATA BOCIAN

    2002-09-01

    Full Text Available The 5-chloro-2-methoxybenzoates of Mn(II, Co(II, Ni(II, Cu(II and Zn(II were synthesized as solids and their magnetic, spectral and thermal properties studied. The complexes possess colours typical of the M(II ions. The thermal stabilities were examined in air and nitrogen atmospheres and the products of decompositions were also identified. The magnetic susceptibilities of the complexes were measured over the temperature range 4.4–300 K and the magnetic moments were calculated. The results show that the 5-chloro-2-methoxybenzoates of Mn(II, Co(II and Ni(II are octahedral, high-spin complexes.

  7. Spectral, structural elucidation and coordination abilities of Co(II) and Mn(II) coordination entities of 2,6,11,15-tetraoxa-9,17-diaza-1,7,10,16-(1,2)-tetrabenzenacyclooctadecaphan-8,17-diene

    Science.gov (United States)

    Rajiv, Kumar; Rajni, Johar

    2011-09-01

    Designing tactics were tailored and followed by synthetic and formulation methodologies to prepare 2,6,11,15-tetraoxa-9,17-diaza-1,7,10,16-(1,2)-tetrabenzenacyclooctadecaphan-8,17-diene. Spectral techniques (MS, infrared, 1H NMR, 13C NMR, electronic and EPR), physiochemical measurements (elemental analysis, molar conductance and magnetic susceptibility), electrochemistry (cyclic voltammetry) and classical mechanics (molecular modeling) were employed for structural elucidation of Co(II) and Mn(II) coordination entities having N 2O 4 chromophore. Comparative spectral analysis revealed legating nature of N 2O 4 donor macrocycle and confirmed host/guest connectivity between ligand and metal(s). Mass spectrometry (MS) determined 1:1 stoichiometry in CEs. Further electrochemical study confirmed change in oxidation and reduction patterns of CEs. Inhibiting potential (antifungal screened against Aspergillus flavus) showed enhanced antimicrobial properties of CEs as compared to ligand. Molecular modeling was employed to find out different molecular features along with their stabilization energies.

  8. Synthesis and spectroscopic studies of biologically active tetraazamacrocyclic complexes of Mn(II, Co(II, Ni(II, Pd(II and Pt(II

    Directory of Open Access Journals (Sweden)

    Monika Tyagi

    2014-01-01

    Full Text Available Complexes of Mn(II, Co(II, Ni(II, Pd(II and Pt(II were synthesized with the macrocyclic ligand, i.e., 2,3,9,10-tetraketo-1,4,8,11-tetraazacycoletradecane. The ligand was prepared by the [2 + 2] condensation of diethyloxalate and 1,3-diamino propane and characterized by elemental analysis, mass, IR and 1H NMR spectral studies. All the complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, IR, electronic and electron paramagnetic resonance spectral studies. The molar conductance measurements of Mn(II, Co(II and Ni(II complexes in DMF correspond to non electrolyte nature, whereas Pd(II and Pt(II complexes are 1:2 electrolyte. On the basis of spectral studies an octahedral geometry has been assigned for Mn(II, Co(II and Ni(II complexes, whereas square planar geometry assigned for Pd(II and Pt(II. In vitro the ligand and its metal complexes were evaluated against plant pathogenic fungi (Fusarium odum, Aspergillus niger and Rhizoctonia bataticola and some compounds found to be more active as commercially available fungicide like Chlorothalonil.

  9. Permanganate-based synthesis of manganese oxide nanoparticles in ferritin

    Science.gov (United States)

    Olsen, Cameron R.; Smith, Trevor J.; Embley, Jacob S.; Maxfield, Jake H.; Hansen, Kameron R.; Peterson, J. Ryan; Henrichsen, Andrew M.; Erickson, Stephen D.; Buck, David C.; Colton, John S.; Watt, Richard K.

    2017-05-01

    This paper investigates the comproportionation reaction of MnII with {{{{MnO}}}4}- as a route for manganese oxide nanoparticle synthesis in the protein ferritin. We report that {{{{MnO}}}4}- serves as the electron acceptor and reacts with MnII in the presence of apoferritin to form manganese oxide cores inside the protein shell. Manganese loading into ferritin was studied under acidic, neutral, and basic conditions and the ratios of MnII and permanganate were varied at each pH. The manganese-containing ferritin samples were characterized by transmission electron microscopy, UV/Vis absorption, and by measuring the band gap energies for each sample. Manganese cores were deposited inside ferritin under both the acidic and basic conditions. All resulting manganese ferritin samples were found to be indirect band gap materials with band gap energies ranging from 1.01 to 1.34 eV. An increased UV/Vis absorption around 370 nm was observed for samples formed under acidic conditions, suggestive of MnO2 formation inside ferritin.

  10. A Multiplex Enzymatic Machinery for Cellular Protein S-nitrosylation.

    Science.gov (United States)

    Seth, Divya; Hess, Douglas T; Hausladen, Alfred; Wang, Liwen; Wang, Ya-Juan; Stamler, Jonathan S

    2018-02-01

    S-nitrosylation, the oxidative modification of Cys residues by nitric oxide (NO) to form S-nitrosothiols (SNOs), modifies all main classes of proteins and provides a fundamental redox-based cellular signaling mechanism. However, in contrast to other post-translational protein modifications, S-nitrosylation is generally considered to be non-enzymatic, involving multiple chemical routes. We report here that endogenous protein S-nitrosylation in the model organism E. coli depends principally upon the enzymatic activity of the hybrid cluster protein Hcp, employing NO produced by nitrate reductase. Anaerobiosis on nitrate induces both Hcp and nitrate reductase, thereby resulting in the S-nitrosylation-dependent assembly of a large interactome including enzymes that generate NO (NO synthase), synthesize SNO-proteins (SNO synthase), and propagate SNO-based signaling (trans-nitrosylases) to regulate cell motility and metabolism. Thus, protein S-nitrosylation by NO in E. coli is essentially enzymatic, and the potential generality of the multiplex enzymatic mechanism that we describe may support a re-conceptualization of NO-based cellular signaling. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Enzymatic Browning: a practical class

    Directory of Open Access Journals (Sweden)

    Maria Teresa Pedrosa Silva Clerici

    2014-10-01

    Full Text Available This paper presents a practical class about the enzymes polyphenol oxidases, which have been shown to be responsible for the enzymatic browning of fruits and vegetables. Vegetables samples were submitted to enzymatic inactivation process with chemical reagents, as well as by bleaching methods of applying heat by conventional oven and microwave oven. Process efficiency was assessed qualitatively by both observing the guaiacol peroxidase activity and after the storage period under refrigeration or freezing. The practical results obtained in this class allow exploring multidisciplinary knowledge in food science, with practical applications in everyday life.

  12. Colors as catalysts in enzymatic reactions.

    Science.gov (United States)

    Azeemi, Samina T Yousuf; Raza, Syed Mohsin; Yasinzai, Masoom

    2008-12-01

    We studied the effects of visible range irradiation (in vitro) on the enzyme solutions (glucose oxidase, cholesterol oxidase + cholesterol esterase and lipase) in order to infer the changes produced in the human body after chromotherapy. The glucose oxidase showed enhanced activity to the color purple (464 nm), while the activity of the other enzymes, cholesterol esterase + cholesterol oxidase and lipase, increased when exposed to dark violet (400 nm). Purple is being used in conventional chromotherapy for diabetes, as supported by the experimental observation in which purple enhanced the activity of enzymes responsible for the oxidation of glucose. Specific wavelengths regulate living processes by acting as catalysts in enzyme activity, while some wavelengths may reduce enzyme activity. The irradiation of specific wavelengths effect enzymatic processes, which as a consequence, accelerated biochemical reactions. This particular frequency when provided to the enzymes (in vitro) lead to changes which may well be occurring in vivo.

  13. New potentiometric transducer based on a Mn(II) [2-formylquinoline thiosemicarbazone] complex for static and hydrodynamic assessment of azides.

    Science.gov (United States)

    Kamel, Ayman H

    2015-11-01

    A new potentiometric transducer for selective recognition of azide is characterized and developed. The PVC plasticized based sensor incorporates Mn(II) [2-formylquinoline thiosemicarbazone] complex in the presence of tri dodecyl methyl ammonium chloride (TDMAC) as a lipophilic cationic additive. The sensor displayed a near-Nernstian response for azide over 1.0×10(-2)-1.0×10(-5) mol L(-1), with an anionic slope of -55.8±0.6 mV decade(-1) and lower limit of detection 0.34 µg mL(-1). The sensor was pH independent in the range 5.5-9 and presented good selectivity features towards several inorganic anions, and it is easily used in a flow injection system and compared with a tubular detector. The intrinsic characteristics of the detector in a low dispersion manifold were determined and compared with data obtained under a hydrodynamic mode of operation. This simple and inexpensive automation, with a good potentiometric detector, enabled the analysis of ~33 samples h(-1) without requiring pre-treatment procedures. The proposed method is also applied to the analysis of trace levels of azide in primer mixtures. Significantly improved accuracy, precision, response time, stability and selectivity were offered by these simple and cost-effective potentiometric sensor compared with other standard techniques. The method has the requisite accuracy, sensitivity and precision to determine azide ions. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Ancient DNA: extraction, characterization, molecular cloning, and enzymatic amplification.

    OpenAIRE

    Pääbo, S

    1989-01-01

    Several chemical and enzymatic properties were examined in the DNA extracted from dry remains of soft tissues that vary in age from 4 to 13,000 years and represent four species, including two extinct animals (the marsupial wolf and giant ground sloth). The DNA obtained was invariably of a low average molecular size and damaged by oxidative processes, which primarily manifest themselves as modifications of pyrimidines and sugar residues as well as baseless sites and intermolecular cross-links....

  15. Kinetic modelling of enzymatic starch hydrolysis

    NARCIS (Netherlands)

    Bednarska, K.A.

    2015-01-01

    Kinetic modelling of enzymatic starch hydrolysis – a summary

    K.A. Bednarska

    The dissertation entitled ‘Kinetic modelling of enzymatic starch hydrolysis’ describes the enzymatic hydrolysis and kinetic modelling of liquefaction and saccharification of wheat starch.

  16. Moderate O3/O2therapy enhances enzymatic and non-enzymatic antioxidant in brain and cochlear that protects noise-induced hearing loss.

    Science.gov (United States)

    Nasezadeh, Parvaneh; Shahi, Farshad; Fridoni, Mohammadjavad; Seydi, Enayatollah; Izadi, Morteza; Salimi, Ahmad

    2017-10-01

    Mitochondrial damage and oxidative stress are known to contribute to the pathogenesis of noise-induced hearing loss (NIHL). In this study, we examined the protective effect of O 2 /O 3 mixture (ozone/oxygen) therapy against mitochondrial induced damage and oxidative stress by noise exposure in rat brain and cochlear. For this purpose, rats were divided into four groups: 1 - control group; 2 - noise-exposed group (100 dB); 3 - noise + O 2 /O 3 , and 4 - O 2 /O 3 (30 µg/ml). After 14 d, animals were anesthetised. Rat brain and cochlear tissue were removed for evaluation of the histopathological damages, oxidative stress, and mitochondrial dysfunction in both tissues. Our findings indicated that noise caused pathological damage, oxidative stress, and mitochondrial dysfunction in rat brain and cochlear. Also, daily administration of an O 2 /O 3 therapy (30 µg/ml intravenous) efficiently increased enzymatic and non-enzymatic antioxidant in brain and cochlear that this action led to inhibition of pathological damages, oxidative stress, reactive oxygen species formation, mitochondrial membrane potential (MMP) collapse, mitochondrial swelling, and cytochrome c release resulting from noise. These findings suggest that the moderate O 2 /O 3 therapy enhances the capacity of enzymatic and non-enzymatic antioxidant in brain and cochlear that protects against NIHL.

  17. Method for the enzymatic production of hydrogen

    Science.gov (United States)

    Woodward, Jonathan; Mattingly, Susan M.

    1999-01-01

    The present invention is an enzymatic method for producing hydrogen comprising the steps of: a) forming a reaction mixture within a reaction vessel comprising a substrate capable of undergoing oxidation within a catabolic reaction, such as glucose, galactose, xylose, mannose, sucrose, lactose, cellulose, xylan and starch. The reaction mixture further comprises an amount of glucose dehydrogenase in an amount sufficient to catalyze the oxidation of the substrate, an amount of hydrogenase sufficient to catalyze an electron-requiring reaction wherein a stoichiometric yield of hydrogen is produced, an amount of pH buffer in an amount sufficient to provide an environment that allows the hydrogenase and the glucose dehydrogenase to retain sufficient activity for the production of hydrogen to occur and also comprising an amount of nicotinamide adenine dinucleotide phosphate sufficient to transfer electrons from the catabolic reaction to the electron-requiring reaction; b) heating the reaction mixture at a temperature sufficient for glucose dehydrogenase and the hydrogenase to retain sufficient activity and sufficient for the production of hydrogen to occur, and heating for a period of time that continues until the hydrogen is no longer produced by the reaction mixture, wherein the catabolic reaction and the electron-requiring reactions have rates of reaction dependent upon the temperature; and c) detecting the hydrogen produced from the reaction mixture.

  18. Method for the enzymatic production of hydrogen

    Science.gov (United States)

    Woodward, J.; Mattingly, S.M.

    1999-08-24

    The present invention is an enzymatic method for producing hydrogen comprising the steps of: (a) forming a reaction mixture within a reaction vessel comprising a substrate capable of undergoing oxidation within a catabolic reaction, such as glucose, galactose, xylose, mannose, sucrose, lactose, cellulose, xylan and starch; the reaction mixture also comprising an amount of glucose dehydrogenase in an amount sufficient to catalyze the oxidation of the substrate, an amount of hydrogenase sufficient to catalyze an electron-requiring reaction wherein a stoichiometric yield of hydrogen is produced, an amount of pH buffer in an amount sufficient to provide an environment that allows the hydrogenase and the glucose dehydrogenase to retain sufficient activity for the production of hydrogen to occur and also comprising an amount of nicotinamide adenine dinucleotide phosphate sufficient to transfer electrons from the catabolic reaction to the electron-requiring reaction; (b) heating the reaction mixture at a temperature sufficient for glucose dehydrogenase and the hydrogenase to retain sufficient activity and sufficient for the production of hydrogen to occur, and heating for a period of time that continues until the hydrogen is no longer produced by the reaction mixture, wherein the catabolic reaction and the electron-requiring reactions have rates of reaction dependent upon the temperature; and (c) detecting the hydrogen produced from the reaction mixture. 8 figs.

  19. A MnII6MnIII6 single-strand molecular wheel with a reuleaux triangular topology: synthesis, structure, magnetism, and DFT studies.

    Science.gov (United States)

    Zartilas, Sotiris; Papatriantafyllopoulou, Constantina; Stamatatos, Theocharis C; Nastopoulos, Vassilios; Cremades, Eduard; Ruiz, Eliseo; Christou, George; Lampropoulos, Christos; Tasiopoulos, Anastasios J

    2013-10-21

    The use of the anion of 3-methyl-1,3,5-pentanetriol (mpt(3-)) in manganese carboxylate chemistry has afforded the new Mn(II/III)12 cluster [Mn(II)6Mn(III)6(mpt)6(CH3CO2)12(py)6]·3CH3CN (1·3CH3CN). Complex 1 was isolated in moderate yield by the reaction of Mn(CH3CO2)2·4H2O and H3mpt in a 2.6:1 molar ratio in a solvent mixture of acetonitrile and pyridine. The structure of 1 consists of alternating [Mn(II)2(CH3CO2)3(py)](+) and [Mn(III)2(μ-OR)2(CH3CO2)(py)](3+) dimeric units (three of each dimer), linked at each end by two alkoxo and one acetate bridges; the mpt(3-) ligands adopt the η(2):η(2):η(2):μ4 coordination mode. The overall metal topology of this new Mn12 wheel resembles a guitar plectrum, or a Reuleaux triangle. Complex 1 displays an unprecedented structural topology, being the first example of a Mn(II)6Mn(III)6 wheel constructed from alternating homovalent dimers and the only known Mn12 loop with the trigonal symmetry of a Reuleaux triangle (all other reported loops were ellipsoids). Variable-temperature, solid-state direct- and alternating-current magnetization studies were carried out on complex 1, revealing the presence of antiferromagnetic exchange interactions between the metal ions in the molecule, which lead to a spin ground-state value S = 0; the exchange coupling parameters J were calculated using density functional theory employing a hybrid B3LYP functional.

  20. Enzymatic reduction of U(VI) in groundwaters

    International Nuclear Information System (INIS)

    Addelouas, A.; Gong, W.; Lutze, W.; Nuttall, E.; Fritz, B.; Crovisier, J.L.

    1999-01-01

    The use of enzymatic reduction of U(VI) in remediation of groundwater contaminated with U(VI) is receiving considerable attention. Certain strains of bacteria can combine the oxidation of an organic compound to the reduction of U(VI) to U(IV), which precipitates as uraninite. In the present study, we tested the reduction of U(VI) in groundwaters with various origins and compositions. In all groundwaters u(VI) was reduced by sulfate reducing bacteria that had been activated by ethanol and tri-metaphosphate. The reduction rate of U(VI) depends on sulfate concentration in water and the abundance of bacteria in the system. This work shows that bacteria capable of U(VI) reduction are ubiquitous in nature, and suggests the possibility of a large application of the enzymatic reduction of U(VI) for in situ clean up of groundwaters contaminated with uranium. (authors)

  1. Biofuel Cells: Enhanced Enzymatic Bioelectrocatalysis

    Science.gov (United States)

    Meredith, Matthew T.; Minteer, Shelley D.

    2012-07-01

    Enzymatic biofuel cells represent an emerging technology that can create electrical energy from biologically renewable catalysts and fuels. A wide variety of redox enzymes have been employed to create unique biofuel cells that can be used in applications such as implantable power sources, energy sources for small electronic devices, self-powered sensors, and bioelectrocatalytic logic gates. This review addresses the fundamental concepts necessary to understand the operating principles of biofuel cells, as well as recent advances in mediated electron transfer- and direct electron transfer-based biofuel cells, which have been developed to create bioelectrical devices that can produce significant power and remain stable for long periods.

  2. Breakthrough Curve Analysis for Column Dynamics Sorption of Mn(II Ions from Wastewater by Using Mangostana garcinia Peel-Based Granular-Activated Carbon

    Directory of Open Access Journals (Sweden)

    Z. Z. Chowdhury

    2013-01-01

    Full Text Available The potential of granular-activated carbon (GAC derived from agrowaste of Mangostene (Mangostana garcinia fruit peel was investigated in batch and fixed bed system as a replacement of current expensive methods for treating wastewater contaminated by manganese, Mn(II cations. Batch equilibrium data was analyzed by Langmuir, Freundlich, and Temkin isotherm models at different temperatures. The effect of inlet metal ion concentration (50 mg/L, 70 mg/L, and 100 mg/L, feed flow rate (1 mL/min and 3 mL/min, and activated carbon bed height (4.5 cm and 3 cm on the breakthrough characteristics of the fixed bed sorption system were determined. The adsorption data were fitted with well-established column models, namely, Thomas, Yoon-Nelson, and Adams-Bohart. The results were best-fitted with Thomas and Yoon-Nelson models rather than Adams-Bohart model for all conditions. The column had been regenerated and reused consecutively for five cycles. The results demonstrated that the prepared activated carbon was suitable for removal of Mn(II ions from wastewater using batch as well as fixed bed sorption system.

  3. Molecular structure and biological studies on Cr(III), Mn(II) and Fe(III) complexes of heterocyclic carbohydrazone ligand

    Science.gov (United States)

    Abu El-Reash, G. M.; El-Gammal, O. A.; Radwan, A. H.

    2014-03-01

    The chelating behavior of the ligand (H2APC) based on carbohydrazone core modified with pyridine end towards Cr(III), Mn(II) and Fe(III) ions have been examined. The 1H NMR and IR data for H2APC revealed the presence of two stereoisomers syn and anti in both solid state and in solution in addition to the tautomeric versatility based on the flexible nature of the hydrazone linkage leading to varied coordination modes. The spectroscopic data confirmed that the ligand behaves as a monobasic tridentate in Cr(III) and Fe(III) complexes and as neutral tetradentate in Mn(II) complex. The electronic spectra as well as the magnetic measurements confirmed the octahedral geometry for all complexes. The bond length and angles were evaluated by DFT method using material studio program for all complexes. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The antioxidant (DDPH and ABTS methods), anti-hemolytic and cytotoxic activities of the compounds have been screened. Cr(III) complex and H2APC showed the highest antioxidant activity using ABTS and DPPH methods. With respect to in vitro Ehrlich ascites assay, H2APC exhibited the potent activity followed by Fe(III) and Cr(III)complexes.

  4. Selective Extraction of Co(II in the Presence of Mn(II, Ni(II and Cu(II Using Salting-out Phase Separation Method

    Directory of Open Access Journals (Sweden)

    A M Shafiqul Alam

    2008-06-01

    Full Text Available Extraction of Co(II in the presence of Mn(II, Ni(II and Cu(II has been studied using the mixture of 2-propanol with water upon the addition of CaCl2 in the concentration range of 3.0 – 5.0 mol dm-3 (M. Co(II was extracted selectively to the extent of 80% into the 2-propanol phase at 5.0 M CaCl2. The percent of extraction of other transition metal ions, for example Mn(II, Ni(II and Cu(II was much lower than that of Co(II, but they were stripped in the aqueous phase upon addition of CaCl2. Therefore, selective extraction of Co(II from these metal ions was attained by using the mixture of water and 2-propanol. Co(II was extracted as CoCl42- from the aqueous phase into the 2-propanol phase through the formation of ion pair, Ca2+ - CoCl42-. A mechanism is proposed to explain the extraction.

  5. Preparation, Investigation and the Study of the Effect of Mn(II Complex of Catechol and 2-Aminopyridine on Seed Germination

    Directory of Open Access Journals (Sweden)

    F. I. El-Moshaty

    2011-01-01

    Full Text Available The formation of mixed ligand complex of Mn(II with catechol (L1 and 2-aminopyridine (L2 was determined by elemental analyses (C, H and N, molar conductance measurement, thermogravimetric analysis, infrared, electronic and electron paramagnetic resonance spectroscopies. The elemental analysis data show the formation of 1:1:1 [M: L1: L2] complex. The molar conductance measurement shows a non-electrolyte nature. The thermogravimetric analysis data of the complex display the existence of hydrated and coordinated water molecules. The infrared spectral data exhibit the coordination sites that are through -OH,-C=N and –NH2 groups. The electronic spectral data display the electronic transitions of the ligands and suggest an octahedral structure for the complex. The electron paramagnetic resonance spectrum of the complex reveals the existence of paramagnetic phenomena and supports its geometrical structure. Seed germination and root length of grass were also assayed under the effect of MnCl2.4H2O, catechol, 2-aminopyridine and its complex. Mn(II salt was the most effective on germination than its complex which possess the high test effect on root length, while the ligands are the least active of all.

  6. Nutrient input influences fungal community composition and size and can stimulate manganese (II) oxidation in caves.

    Science.gov (United States)

    Carmichael, Sarah K; Zorn, Bryan T; Santelli, Cara M; Roble, Leigh A; Carmichael, Mary J; Bräuer, Suzanna L

    2015-08-01

    Little is known about the fungal role in biogeochemical cycling in oligotrophic ecosystems. This study compared fungal communities and assessed the role of exogenous carbon on microbial community structure and function in two southern Appalachian caves: an anthropogenically impacted cave and a near-pristine cave. Due to carbon input from shallow soils, the anthropogenically impacted cave had an order of magnitude greater fungal and bacterial quantitative-polymerase chain reaction (qPCR) gene copy numbers, had significantly greater community diversity, and was dominated by ascomycotal phylotypes common in early phase, labile organic matter decomposition. Fungal assemblages in the near-pristine cave samples were dominated by Basidiomycota typically found in deeper soils (and/or in late phase, recalcitrant organic matter decomposition), suggesting more oligotrophic conditions. In situ carbon and manganese (II) [Mn(II)] addition over 10 weeks resulted in growth of fungal mycelia followed by increased Mn(II) oxidation. A before/after comparison of the fungal communities indicated that this enrichment increased the quantity of fungal and bacterial cells, yet decreased overall fungal diversity. Anthropogenic carbon sources can therefore dramatically influence the diversity and quantity of fungi, impact microbial community function, and stimulate Mn(II) oxidation, resulting in a cascade of changes that can strongly influence nutrient and trace element biogeochemical cycles in karst aquifers. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  7. THEORY DEVELOPMENT OF ENZYMATIC AROMA RECOVERY

    Directory of Open Access Journals (Sweden)

    G. E. Dubova

    2014-01-01

    Full Text Available Summary. The fruit and vegetable pretreatment conditions and subsequent environment in which enzymatic reactions take place can be considered as potential factors in the formation of fresh flavors. The synthesis of aromatic components of fresh grass and green leaves occurs involving vegetable lipoxygenases. The molecules of a precursor-compound can withstand the processing modes, while enzymes and aromatic compounds break down frequently. Vegetable homogenates are potential sources of enzymes which produce natural aromatic substances. Formation of fresh favors is the most perceptible when it occurs as the result of the reaction between poliunsaturated fatty acids of cytoplasmic membranes and lipoxygenases and hydroperoxide lyase of plant material. Pre-treatment of samples positively influences binding energy in the complex of enzyme-substrate. The change of iodine number in treated homogenates, as compared to fresh ones, shows isomerization of flavor precursors. The minimal quantity of homogenates introduced (up to 20 g and the duration of aroma-restoring reaction (from 5 to 7 minutes were defined. Pre-cooling of homogenates activates enzymes, strengthens oxidability of the PUFA, and results in recovery of fresh aroma of plant material. Under conditions of enzyme inactivation, the synthesis of aromas is not possible. Conversely, production of aroma in food glazes and foams is possible in case of interphase activation between a substrate and enzymes.

  8. Single or combined effects of mannan-oligosaccharides and probiotic supplements on the total oxidants, total antioxidants, enzymatic antioxidants, liver enzymes, and serum trace minerals in cyclic heat-stressed broilers.

    Science.gov (United States)

    Sohail, M U; Rahman, Z U; Ijaz, A; Yousaf, M S; Ashraf, K; Yaqub, T; Zaneb, H; Anwar, H; Rehman, H

    2011-11-01

    This study was intended to explore the oxidative status of broilers under cyclic heat stress (HS) as modulated by supplementation of mannan-oligosaccharides (MOS) and a probiotic mixture (PM). Two hundred fifty 1-d-old chicks were randomly divided into 5 groups. From d 22, birds were either kept in a thermoneutral zone (TN; 26.7°C for 24 h/d) or subjected to HS (35 ± 1.1°C and 75 ± 5% RH for 8 h/d from 1000 to 1800 h) to the conclusion of the study on d 42. Birds were fed either a corn-based diet (TN and HS groups) or the same diet supplemented with 0.5% MOS (HS-MOS group), 0.1% PM (HS-PM group), or their combination as a symbiotic (SYN; HS-SYN group). On d 42, birds were killed by cervical dislocation to collect serum for the determination of total oxidants, total antioxidants, paraoxonase, arylesterase, ceruloplasmin, aspartate aminotransferase, alanine aminotransferase, and trace minerals. Heat stress increased (P trace minerals, whereas SYN increased (P trace minerals.

  9. Organic synthesis - applications in enzymatic studies, catalysis and surface modification

    DEFF Research Database (Denmark)

    Viart, Helene Marie-France

    as liposomes and the enzymatic activity was studied. Hydrolysis (or absence of hydrolysis) was monitored by MALDI-TOF-MS. The results observedin these experiments are compared to MD predictions and confirm them. The second chapter deals with surface functionalization of liposomes. The copper mediated [3......: a C3symmetric phosphine oxide has been synthesised, which we intend to test, after reduction to the phosphin, as a ligand in organometallic catalysed reactions. The ultimate goal is to obtain enantioselectivity, introduced by the organization of aryl substituents around phosphorous in our ligand....

  10. Review of the literature on enzymatic reduction of nitrocompounds

    Energy Technology Data Exchange (ETDEWEB)

    Hadley, W.M.

    1983-02-01

    If more accurate assessment of the risk associated with human exposure to nitrocompounds (NCs) in combustion products, drugs, industrial chemicals and agricultural chemicals are to be made. An understanding of the enzymatic reduction of NCs must be acquired. This review covers the literature through November 1982 on reduction by enzymes of nitro groups attached to organic compounds. Much of the nitroreduction literature has focused on the metabolism of p-nitrobenzoic acid, 4-nitroquinoline 1-oxide, the nitrofurans, and the nitroimidazoles. A few papers report the reduction of other NCs such as the nitrophenols, nitrotoluenes and nitrobenzenes. Only very limited information is available on the reductive metabolism of multi-ring NCs.

  11. Fusion to Flaviviral Leader Peptide Targets HIV-1 Reverse Transcriptase for Secretion and Reduces Its Enzymatic Activity and Ability to Induce Oxidative Stress but Has No Major Effects on Its Immunogenic Performance in DNA-Immunized Mice

    Directory of Open Access Journals (Sweden)

    Anastasia Latanova

    2017-01-01

    Full Text Available Reverse transcriptase (RT is a key enzyme in viral replication and susceptibility to ART and a crucial target of immunotherapy against drug-resistant HIV-1. RT induces oxidative stress which undermines the attempts to make it immunogenic. We hypothesized that artificial secretion may reduce the stress and make RT more immunogenic. Inactivated multidrug-resistant RT (RT1.14opt-in was N-terminally fused to the signal providing secretion of NS1 protein of TBEV (Ld generating optimized inactivated Ld-carrying enzyme RT1.14oil. Promotion of secretion prohibited proteasomal degradation increasing the half-life and content of RT1.14oil in cells and cell culture medium, drastically reduced the residual polymerase activity, and downmodulated oxidative stress. BALB/c mice were DNA-immunized with RT1.14opt-in or parental RT1.14oil by intradermal injections with electroporation. Fluorospot and ELISA tests revealed that RT1.14opt-in and RT1.14oil induced IFN-γ/IL-2, RT1.14opt-in induced granzyme B, and RT1.14oil induced perforin production. Perforin secretion correlated with coproduction of IFN-γ and IL-2 (R=0,97. Both DNA immunogens induced strong anti-RT antibody response. Ld peptide was not immunogenic. Thus, Ld-driven secretion inferred little change to RT performance in DNA immunization. Positive outcome was the abrogation of polymerase activity increasing safety of RT-based DNA vaccines. Identification of the molecular determinants of low cellular immunogenicity of RT requires further studies.

  12. Enzymatic determination of cadmium, zinc, and lead in plant materials

    International Nuclear Information System (INIS)

    Muginova, S.V.; Veselova, I.A.; Parova, L.M.; Shekhovtseva, T.N.

    2008-01-01

    Prospects are outlined for using the following enzymes (native and immobilized on polyurethane foam) in the rapid and highly sensitive determination of cadmium, zinc, and lead ions in plant materials (wild grass, fresh pea, and grape): horseradish peroxidase and alkaline phosphatases isolated from chicken intestine and Greenland seal small intestine. The analytical ranges of the above metals are 1x10 -3 -25; 7x10 -3 -250, and 3x10 -2 -67 mg/kg dry matter, respectively. The enzymatic determination procedures developed are based on the inhibiting effect of metal ions on the catalytic activity of peroxidase in the oxidation of o-dianisidine with hydrogen peroxide and alkaline phosphatases in the hydrolysis of p-nitrophenyl phosphate. The rates of enzymatic reactions were monitored spectrophotometrically or visually. In the analysis of plant extracts, their high acidity was diminished by choosing optimum dilution factors and pH values for test samples and the nature and concentration of a buffer solution. The interference of iron(III) was removed by introducing a 0.1 M tartaric acid solution into the indicator reaction. The accuracy of the results of the enzymatic determination of cadmium, zinc, and lead in plant materials was supported by atomic absorption spectrometry and anodic stripping voltammetry [ru

  13. Enzymatic acylglycerol synthesis in membrane reactor systems

    NARCIS (Netherlands)

    Padt, van der A.

    1993-01-01

    Up till twenty years ago, only chemical modifications of agricultural oils for novel uses were studied. Because of the instability of various fatty acids, enzymatic biomodifications can have advantages above the chemical route. Nowadays, enzymatic catalysis can be used for the modification

  14. Condições de secagem de uma pasta de anchoita modificada enzimaticamente na oxidação lipídica, lisina disponível e atividade antioxidante do produto Drying conditions of an enzymatic modified paste of anchovy in the lipid oxidation, available lisina and antioxidant activity of the product

    Directory of Open Access Journals (Sweden)

    Kelly de Moraes

    2013-03-01

    Full Text Available O objetivo do trabalho foi analisar as condições da secagem convectiva de uma pasta de anchoita (Engraulis anchoita modificada enzimaticamente, através da metodologia de superfícies de resposta, sendo as respostas consideradas: a oxidação lipídica (TBA, a redução da lisina disponível e a perda da atividade antioxidante específica. A pasta de anchoita modificada foi obtida por hidrólise enzimática da fração muscular (filés do pescado por Neutrase®. Foram avaliadas na operação de secagem, a temperatura do ar (60, 70 e 80°C e a espessura das amostras (1,5; 2,5 e 3,5mm. A análise estatística da secagem mostrou efeitos significativos da temperatura do ar e da espessura das amostras (PThe aim of the work was to analyze the conditions of the convective drying of an enzymatic modified paste of anchovy (Engraulis anchoita through the response surfaces methodology, and the responses were the lipid oxidation (TBA, reduction of the available lisina and loss of the specific antioxidant activity. The modified paste of anchovy was obtained through enzymatic hydrolysis of the fish muscular fraction (fillets by Neutrase®. In drying operation the air temperature (60, 70 and 80°C and the samples thickness (1.5, 2.5 and 3.5mm were studied. The statistical analysis of the drying showed significant effects of the air temperature and samples thickness (P<0.05. The best drying condition was obtained in the air temperature of 60°C and samples thickness of 2.5mm. In this condition the TBA index was of 0.93mgMDA kg-1, available lisina reduction of 16% and loss of the specific antioxidant activity of 20.2%.

  15. An Enzymatic Bioassay for Perchlorate

    Science.gov (United States)

    2010-07-01

    idea of using DTT as an antioxidant in the reaction was abandoned. Figure 26. Effect of cysteine on the oxidation of NADH by Pcr in the presence of...oxidized by molecular oxygen. The experiments shown above disproved the hypothesis that antioxidants could be added to the reaction to quench molecular... polypropylene tubes and spun in a Beckman TI-50 centrifuge at 35,000 RPM for 1 hour. The supernatant was retained, and the pellet was discarded

  16. The effects of xylitol and sorbitol on lysozyme- and peroxidase-related enzymatic and candidacidal activities.

    Science.gov (United States)

    Kim, Bum-Soo; Chang, Ji-Youn; Kim, Yoon-Young; Kho, Hong-Seop

    2015-07-01

    To investigate whether xylitol and sorbitol affect enzymatic and candidacidal activities of lysozyme, the peroxidase system, and the glucose oxidase-mediated peroxidase system. Xylitol and sorbitol were added to hen egg-white lysozyme, bovine lactoperoxidase, glucose oxidase-mediated peroxidase, and whole saliva in solution and on hydroxyapatite surfaces. The enzymatic activities of lysozyme, peroxidase, and glucose oxidase-mediated peroxidase were determined by the turbidimetric method, the NbsSCN assay, and production of oxidized o-dianisidine, respectively. Candidacidal activities were determined by comparing colony forming units using Candida albicans ATCC strains 10231, 11006, and 18804. While xylitol and sorbitol did not affect the enzymatic activity of hen egg-white lysozyme both in solution and on hydroxyapatite surfaces, they did inhibit the enzymatic activity of salivary lysozyme significantly in solution, but not on the surfaces. Xylitol and sorbitol enhanced the enzymatic activities of both bovine lactoperoxidase and salivary peroxidase significantly in a dose-dependent manner in solution, but not on the surfaces. Sorbitol, but not xylitol, inhibited the enzymatic activity of glucose oxidase-mediated peroxidase significantly. Both xylitol and sorbitol did not affect candidacidal activities of hen egg-white lysozyme, the bovine lactoperoxidase system, or the glucose oxidase-mediated bovine lactoperoxidase system. Xylitol and sorbitol inhibited salivary lysozyme activity, but enhanced both bovine lactoperoxidase and salivary peroxidase activities significantly in solution. Xylitol and sorbitol did not augment lysozyme- and peroxidase-related candidacidal activities. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Population structure of manganese-oxidizing bacteria in stratified soils and properties of manganese oxide aggregates under manganese-complex medium enrichment.

    Directory of Open Access Journals (Sweden)

    Weihong Yang

    Full Text Available Manganese-oxidizing bacteria in the aquatic environment have been comprehensively investigated. However, little information is available about the distribution and biogeochemical significance of these bacteria in terrestrial soil environments. In this study, stratified soils were initially examined to investigate the community structure and diversity of manganese-oxidizing bacteria. Total 344 culturable bacterial isolates from all substrata exhibited Mn(II-oxidizing activities at the range of 1 µM to 240 µM of the equivalent MnO2. The high Mn(II-oxidizing isolates (>50 mM MnO2 were identified as the species of phyla Actinobacteria, Firmicutes and Proteobacteria. Seven novel Mn(II-oxidizing bacterial genera (species, namely, Escherichia, Agromyces, Cellulomonas, Cupriavidus, Microbacterium, Ralstonia, and Variovorax, were revealed via comparative phylogenetic analysis. Moreover, an increase in the diversity of soil bacterial community was observed after the combined enrichment of Mn(II and carbon-rich complex. The phylogenetic classification of the enriched bacteria represented by predominant denaturing gradient gel electrophoresis bands, was apparently similar to culturable Mn(II-oxidizing bacteria. The experiments were further undertaken to investigate the properties of the Mn oxide aggregates formed by the bacterial isolates with high Mn(II-oxidizing activity. Results showed that these bacteria were closely encrusted with their Mn oxides and formed regular microspherical aggregates under prolonged Mn(II and carbon-rich medium enrichment for three weeks. The biotic oxidation of Mn(II to Mn(III/IV by these isolates was confirmed by kinetic examinations. X-ray diffraction assays showed the characteristic peaks of several Mn oxides and rhodochrosite from these aggregates. Leucoberbelin blue tests also verified the Mn(II-oxidizing activity of these aggregates. These results demonstrated that Mn oxides were formed at certain amounts under the

  18. Synthesis, spectroscopic characterization, DFT calculations and biological evaluation of benzothiazole derivative bearing Mn(II) and Ni(II) metal ions

    Science.gov (United States)

    El-Gamel, Nadia E. A.; Ali, Korany A.

    2017-11-01

    N-(benzo[d]thiazol-2-yl)-3-oxo-3-phenylpropanamide ligand and its Nickel and Manganese complexes have been synthesized and characterized by elemental and thermal analyses, IR, diffuse reflectance, mass and UV-Vis spectra, molar conductance and magnetic moment measurements. The decomposition mechanism and thermal stability of the investigated complexes are interpreted in terms of their structures. The thermal behaviour of the complexes has been studied and different thermodynamic parameters are calculated using Coats-Redfern method. N-(benzo[d]thiazol-2-yl)-3-oxo-3-phenylpropanamide is a neutral bidentate ligand coordinating metal ions via thiazole ring nitrogen and amide carbonyl O forming high spin octahedral complexes with Mn(II) (2) and distorted square planar in case of Ni(II) (1). Natural bond orbital analysis and geometry optimization were carried out at DFT/B3LYP/6-31G(d) level of theory for the ligand and the mentioned complexes. Ab inito computations at the HF/6-31G(d) level of the theory is conducted in order to detect any probability of a hydrogen bond formation in the ligand. The dipole moment of the Ni(II) and Mn(II) complexes is recorded to be 9.69 and 7.39 Debye, respectively, indicating that the complexes are more polarized than the ligand 2.39 Debye. The in vitro biological activity of the metal chelates is screened against the Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), fungus (Aspergillus flavus, Candida albicans). Ni(II) complexes displayed the highest activity against Candida albicans and Staphylococcus aureus with MIC values of 13, 30 μg/cm3, respectively.

  19. Synthesis, spectral, thermal and magnetic studies of Mn(II), Ni(II) and Cu(II) complexes with some benzopyran-4-one Schiff bases

    Science.gov (United States)

    El-Ansary, Aida L.; Abdel-Fattah, Hussein M.; Abdel-Kader, Nora S.

    2011-08-01

    The Schiff bases of N 2O 2 dibasic ligands, H 2La and H 2Lb are prepared by the condensation of ethylenediamine (a) and trimethylenediamine (b) with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one. Also tetra basic ligands, H 4La and H 4Lb are prepared by the condensation of aliphatic amines (a) and (b) with 6-formyl-5,7-dihydroxy-2-methylbenzopyran-4-one. New complexes of H 4La and H 4Lb with metal ions Mn(II), Ni(II) and Cu(II) are synthesized, in addition Mn(II) complexes with ligands H 2La and H 2Lb are also synthesized. Elemental and thermal analyses, infrared, ultraviolet-visible as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. The structures of copper(II) complexes are also assigned based upon ESR spectra study. All the complexes separated with the stoichiometric ratio (1:1) (M:L) except Mn-H 4La and Mn-H 4Lb with (2:1) (M:L) molar ratio. In metal chelates of the type 1:1 (M:L), the Schiff bases behave as a dinegative N 2O 2 tetradentate ligands. Moreover in 2:1 (M:L) complexes, the Schiff base molecules act as mono negative bidentate ligand and binuclear complex is then formed. The Schiff bases were assayed by the disc diffusion method for antibacterial activity against Staphylococcus aureus and Escherichia coli. The antifungal activity of the Schiff bases was also evaluated against the fungi Aspergillus flavus and Candida albicans.

  20. Enzymatic gelation of sugar beet pectin in food products

    DEFF Research Database (Denmark)

    Bergsøe, Merete Norsker; Jensen, Mette; Adler-Nissen, Jens

    2000-01-01

    was formed which bound the meat pieces together thereby making the product sliceable. However, in two of the food products some unwanted side effects were observed. The enzymes did not only catalyse the cross-linking, but also oxidised the anthocyanins in the black currant juice and short chained fatty acids......Sugar beet pectin is a food ingredient with specific functional properties. It may form gels by an oxidative cross-linking of ferulic acid. In the present study, the gel forming properties of three oxidative enzymes were examined in different food relevant conditions. The enzymes chosen were two...... laccases and one peroxidase. The textural properties of the produced gels were measured on a texture analyser. The influence of sugar, salt and protein were analysed. Finally, the enzymatic gelation was studied in three food products with added sugar beet pectin. These were black currant juice, milk...

  1. Enzymatic synthesis of C-11 formaldehyde: concise communication

    International Nuclear Information System (INIS)

    Slegers, G.; Lambrecht, R.H.D.; Vandewalle, T.; Meulewaeter, L.; Vandecasteele, C.

    1984-01-01

    An enzymatic synthesis of C-11 formaldehyde from C-11 methanol is presented, with immobilized alcohol oxidase and catalase: a rapid, simple procedure, with a high and reproducible yield. Carbon-11 methanol is oxidized to C-11 formaldehyde by passage over a column on which the enzymes alcohol oxidase and catalase are immobilized. The catalase increases reaction velocity by recycling the oxygen, and prevents destruction of the alcohol oxidase by eliminating the excess of hydrogen peroxide. The yield of the enzyme-catalyzed oxidation was 80-95%. A specific activity of 400-450 mCi/μmole was obtained at EOB + 20 min. Various immobilization techniques and the optimal reaction conditions of the immobilized enzymes are investigated

  2. Recent advances in Carbon Nanotube based Enzymatic Fuel Cells

    Directory of Open Access Journals (Sweden)

    Serge eCosnier

    2014-10-01

    Full Text Available This review summarizes recent trends in the field of enzymatic fuel cells. Thanks to the high specificity of enzymes, biofuel cells can generate electrical energy by oxidation of a targeted fuel (sugars, alcohols or hydrogen at the anode and reduction of oxidants (O2, H2O2 at the cathode in complex media. The combination of carbon nanotubes, enzymes and redox mediators was widely exploited to develop biofuel cells since the electrons, involved in the bio-electrocatalytic processes, can be efficiently transferred from or to an external circuit. Original approaches to construct electron transfer based CNT-bioelectrodes and impressive biofuel cell performances are reported as well as biomedical applications.

  3. Detection of extracellular enzymatic activity in microorganisms ...

    African Journals Online (AJOL)

    Detection of extracellular enzymatic activity in microorganisms isolated from waste vegetable oil contaminated soil using plate methodologies. Eugenia G. Ortiz Lechuga, Isela Quintero Zapata, Katiushka Arévalo Niño ...

  4. IMPORTANCE OF ENZYMATIC BIOTRANSFORMATION IN IMMUNOTOXICOLOGY

    Science.gov (United States)

    Many immunotoxic compounds, such as benzene and other organic solvents, pesticides, mycotoxins and polycyclic aromatic hydrocarbons, can alter immune function only after undergoing enzyme-mediated reactions within various tissues. In the review that follows, the role of enzymatic...

  5. Enzymatic synthesis of isotopically labelled purine deoxyribonucleotides

    International Nuclear Information System (INIS)

    Frank-Kamenetskaya, M.D.; Myasoedov, N.F.

    1992-01-01

    An enzymatic method is described which makes it possible to synthesize labelled purine deoxyribonucleotides from corresponding labelled purine ribonucleotides using the RDP-reductase system of ether-treated E. coli E125 cells. (Author)

  6. Single-molecule theory of enzymatic inhibition.

    Science.gov (United States)

    Robin, Tal; Reuveni, Shlomi; Urbakh, Michael

    2018-02-22

    The classical theory of enzymatic inhibition takes a deterministic, bulk based approach to quantitatively describe how inhibitors affect the progression of enzymatic reactions. Catalysis at the single-enzyme level is, however, inherently stochastic which could lead to strong deviations from classical predictions. To explore this, we take the single-enzyme perspective and rebuild the theory of enzymatic inhibition from the bottom up. We find that accounting for multi-conformational enzyme structure and intrinsic randomness should strongly change our view on the uncompetitive and mixed modes of inhibition. There, stochastic fluctuations at the single-enzyme level could make inhibitors act as activators; and we state-in terms of experimentally measurable quantities-a mathematical condition for the emergence of this surprising phenomenon. Our findings could explain why certain molecules that inhibit enzymatic activity when substrate concentrations are high, elicit a non-monotonic dose response when substrate concentrations are low.

  7. Kinetics of enzymatic hydrolysis of methyl ricinoleate

    OpenAIRE

    Neeharika, T. S.V.R.; Lokesh, P.; Prasanna Rani, K. N.; Prathap Kumar, T.; Prasad, R. B.N.

    2015-01-01

    Ricinoleic acid is an unsaturated hydroxy fatty acid that naturally occurs in castor oil in proportions of up to 85–90%. Ricinoleic acid is a potential raw material and finds several applications in coatings, lubricant formulations and pharmaceutical areas. Enzymatic hydrolysis of castor oil is preferred over conventional hydrolysis for the preparation of ricinoleic acid to avoid estolide formation. A kinetics analysis of the enzymatic hydrolysis of Methyl Ricinoleate in the presence of Candi...

  8. [Isolation and identification of Mn oxidizing bacterium Aminobacter sp. H1 and its oxidation mechanism].

    Science.gov (United States)

    Yan, Ping; Jiang, Li-Ying; Chen, Jian-Meng; He, Zhi-Min; Xiao, Shao-Dan; Jiang, Yi-Feng

    2014-04-01

    A bacterium with high manganese oxidizing activity was isolated from a biological manganese removal filter and named as H1. Based on its characteristics and the analysis of 16S rDNA sequence, the strain H1 belonged to the genus Aminobacter sp. and its manganese oxidizing ability had never been reported. In this paper, the microbiologic properties of the strain H1, the manganese oxidation mechanisms and characteristics of biogenic manganese oxides were investigated. The results showed that the maximal tolerant Mn concentration of strain H1 was 50 mmol x L(-1), and Mn(II) could be completely removed by strain H1 when the concentration was lower than 10 mmol x L(-1). Strain H1 could oxidize Mn2+ by both the production of manganese oxidizing activity factor and alkaline metabolites during growth, which were synthesized in the cell and then secreted into extracellular culture medium. During the oxidation process, the intermediate of soluble Mn(III) was detected. SEM showed that the biogenic manganese oxides were amorphous and poorly-crystalline, and it closely combined with bacteria. The components of the biogenic manganese oxides produced by strain H1 were identified as MnCO3, MnOOH, Mn3O4 and MnO2 by XRD, XPS and SEM-EDX.

  9. Synthesis, characterization, fluorescence and biological studies of Mn(II, Fe(III and Zn(II complexes of Schiff bases derived from Isatin and 3-substituted-4-amino-5-mercapto-1,2,4-triazoles

    Directory of Open Access Journals (Sweden)

    Sangamesh A. Patil

    2014-12-01

    Full Text Available A series of Mn(II, Fe(III and Zn(II complexes have been synthesized with Schiff bases derived from isatin and 3-substituted-4-amino-5-mercapto-1,2,4-triazole. The elemental, spectroscopic (Infrared, nuclear magnetic resonance, ultraviolet-visible, fast atom bombardment-mass, fluorescence and electrochemistry and magnetic studies suggested that the metal complexes possess octahedral geometry. The Schiff bases and their metal complexes exhibit fluorescent properties. The antimicrobial studies of Schiff bases and their metal complexes against various bacterial (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis and fungal (Aspergillus niger, and Penicillium chrysogenum species by the minimum inhibitory concentration method revealed that the metal complexes possess more healing antibacterial activities than the Schiff bases. DNA cleavage property of Mn(II, Fe(III and Zn(II complexes revealed the important role of metal ion in the biological system.

  10. Synthesis, spectroscopic characterization, molecular modeling and antimicrobial activities of Mn(II), Co(II), Ni(II), Cu(II) complexes containing the tetradentate aza Schiff base ligand

    Science.gov (United States)

    Chandra, Sulekh; Ruchi

    2013-02-01

    Mn(II), Co(II), Ni(II), and Cu(II) complexes with a tetradentate macrocyclic ligand [1.2.5.6tetraoxo-3,4,7,8tetraaza-(1,2,3,4,5,6,7,8)tetrabenzene(L)] were synthesized and characterized by elemental analysis, molar conductance measurements, mass, nmr, i.r., electronic and e.p.r. spectral studies. All the complexes are non electrolytes in nature and may be formulated as [M(L)X2] [where, M = Mn(II), Co(II), Ni(II), Cu(II) and X = Cl-, CH3COO-]. On the basis of i.r., electronic and e.p.r. spectral studies a distorted octahedral geometry has been assigned for all complexes. The antimicrobial activities and LD50 values of the ligand and its complexes, as growth inhibiting agents, have been screened in vitro against two different species of bacteria and plant pathogenic fungi.

  11. Enzymatic hydrolysis and ethanol fermentation of high dry matter wet-exploded wheat straw at low enzyme loading

    DEFF Research Database (Denmark)

    Georgieva, T.I.; Hou, Xiaoru; Hilstrøm, Troels

    2008-01-01

    Wheat straw was pretreated by wet explosion using three different oxidizing agents (H2O2, O-2, and air). The effect of the pretreatment was evaluated based on glucose and xylose liberated during enzymatic hydrolysis. The results showed that pretreatment with the use of O-2 as oxidizing agent was ...... and a low enzyme loading of 10 FPU/g cellulose in an industrial acceptable time frame of 96 h. Cellulose and hemicellulose conversion from enzymatic hydrolysis were 70 and 68%, respectively, and an overall ethanol yield from SSF was 68%....

  12. New Mn(II, Ni(II, Cd(II, Pb(II complexes with 2-methylbenzimidazole and other ligands. Synthesis, spectroscopic characterization, crystal structure, magnetic susceptibility and biological activity studies

    Directory of Open Access Journals (Sweden)

    Shayma A. Shaker

    2016-11-01

    Full Text Available Synthesis and characterization of Mn(II, Ni(II, Cd(II and Pb(II mixed ligand complexes of 2-methylbenzimidazole with other ligands have been reported. The structure of the ligands and their complexes was investigated using elemental analysis, IR, UV–Vis, (1H, 13C NMR spectroscopy, molar conductivity and magnetic susceptibility measurements. In all the studies of complexes, the 2-methylbenzimidazole behaves as a neutral monodentate ligand which is coordinated with the metal ions through the N atom. While benzotriazole behaves as a neutral bidentate ligand which is coordinated with the Ni(II ion through the two N atoms. Moreover, the N-acetylglycine behaves as a bidentate ligand which is coordinated with the Mn(II, Ni(II and Pb(II ions through the N atom and the terminal carboxyl oxygen atom. The magnetic and spectral data indicate the tetrahedral geometry for Mn(II complex, irregular tetrahedral geometry for Pb(II complex and octahedral geometry for Ni(II complex. The X-ray single crystal diffraction method was used to confirm a centrosymmetric dinuclear Cd(II complex as each two metal ions are linked by a pair of thiocyanate N = S bridge. Two 2-methylbenzimidazole N-atom donors and one terminal thiocyanate N atom complete a highly distorted square pyramid geometry around the Cd atom. Besides, different cell types were used to determine the inhibitory effect of Mn(II, Ni(II, Cd(II and Pb(II complexes on cell growth using MTT assay. Cd(II complex showed cytotoxic effect on various types of cancer cell lines with different EC50 values.

  13. Kinetics of Melanin Polymerization during Enzymatic and Nonenzymatic Oxidation.

    Science.gov (United States)

    Mondal, Sayan; Thampi, Arya; Puranik, Mrinalini

    2018-02-22

    Melanin is an abundant biopigment in the animal kingdom, but its structure remains poorly understood. This is a substantial impediment to understanding the mechanistic origin of its observed functions. Proposed models of melanin structure include aggregates of both linear and macrocyclic units and noncovalently held monomers. Both models are broadly in agreement with current experimental data. To constrain the structural and kinetic models of melanin, experimental data of high resolution with chemical specificity accompanied by atomistic modeling are required. We have addressed this by obtaining electronic absorption, infrared, and ultraviolet resonance Raman (RR) spectra of melanin at several wavelengths of excitation that are sensitive to small changes in structure. From these experiments, we observed kinetics of the formation of different species en route to melanin polymerization. Exclusive chemical signatures of monomer 3,4-dihydroxyphenylalanine (dopa), intermediate dopachrome (DC), and early-time polymer are established through their vibrational bands at 1292, 1670, and 1616 cm -1 respectively. Direct evidence of reduced heterogeneity of melanin oligomers in tyrosinase-induced formation is provided from experimental measurements of vibrational bandwidths. Models made with density functional theory show that the linear homopolymeric structures of 5,6-dihydroxyindole can account for experimentally observed wavenumbers and broad bandwidth in Raman spectra of dopa-melanin. We capture resonance Raman (RR) signature of DC, the intermediate stabilized by the enzyme tyrosinase, for the first time in an enzyme-assisted melanization reaction using 488 nm excitation wavelength and propose that this wavelength can be used to probe reaction intermediates of melanin formation in solution.

  14. Fluorescence-detected X-ray magnetic circular dichroism of well-defined Mn(II) and Ni(II) doped in MgO crystals: credential evaluation for measurements on biological samples.

    Science.gov (United States)

    Wang, Hongxin; Bryant, Craig; LeGros, M; Wang, Xin; Cramer, S P

    2012-10-18

    L(2,3)-edge X-ray magnetic circular dichroism (XMCD) spectra have been measured for the well-defined dilute Ni(II) and Mn(II) ions doped into a MgO crystal, with sub-Kelvin dilution refrigerator cooling and 2 T magnetic field magnetization. A 30-element Ge array X-ray detector has been used to measure the XMCD for these dilute ions, whose concentrations are 1400 ppm for Ni(II) and 10,000 ppm for Mn(II). Large XMCD effects have been observed for both Ni(II) and Mn(II), and multiplet simulation described the observed spectra. The fluorescence-detected L-edge absorption spectrum and XMCD of Ni(II) in MgO are comparable with both theoretical calculations and the total electron yield measured ions in similar chemical environments, at least qualitatively validating the use of the sensitive fluorescence detection technique for studying XMCD for dilute 3d metal ions, such as various metalloproteins. Sum rule analyses on the XMCD spectra are also performed. In addition, these XMCD measurements have also been used to obtain the sample's magnetization curve and the beamline's X-ray helicity curve. This study also illustrated that bend magnet beamlines are still useful in examining XMCD on dilute and paramagnetic metal sites.

  15. A wheel-shaped single-molecule magnet of [MnII 3MnIII 4]: quantum tunneling of magnetization under static and pulse magnetic fields.

    Science.gov (United States)

    Koizumi, Satoshi; Nihei, Masayuki; Shiga, Takuya; Nakano, Motohiro; Nojiri, Hiroyuki; Bircher, Roland; Waldmann, Oliver; Ochsenbein, Stefan T; Güdel, Hans U; Fernandez-Alonso, Felix; Oshio, Hiroki

    2007-01-01

    The reaction of N-(2-hydroxy-5-nitrobenzyl)iminodiethanol (=H3(5-NO2-hbide)) with Mn(OAc)2* 4 H2O in methanol, followed by recrystallization from 1,2-dichloroethane, yielded a wheel-shaped single-molecule magnet (SMM) of [MnII 3MnIII 4(5-NO2-hbide)6].5 C2H4Cl2 (1). In 1, seven manganese ions are linked by six tri-anionic ligands and form the wheel in which the two manganese ions on the rim and the one in the center are MnII and the other four manganese ions are MnIII ions. Powder magnetic susceptibility measurements showed a gradual increase with chimT values as the temperature was lowered, reaching a maximum value of 53.9 emu mol(-1) K. Analyses of magnetic susceptibility data suggested a spin ground state of S=19/2. The zero-field splitting parameters of D and B 0 4 were estimated to be -0.283(1) K and -1.64(1)x10(-5) K, respectively, by high-field EPR measurements (HF-EPR). The anisotropic parameters agreed with those estimated from magnetization and inelastic neutron scattering experiments. AC magnetic susceptibility measurements showed frequency-dependent in- and out-of-phase signals, characteristic data for an SMM, and an Arrhenius plot of the relaxation time gave a re-orientation energy barrier (DeltaE) of 18.1 K and a pre-exponential factor of 1.63x10(-7) s. Magnetization experiments on aligned single crystals below 0.7 K showed a stepped hysteresis loop, confirming the occurrence of quantum tunneling of the on magnetization (QTM). QTM was, on the other hand, suppressed by rapid sweeps of the magnetic field even at 0.5 K. The sweep-rate dependence of the spin flips can be understood by considering the Landau-Zener-Stückelberg (LZS) model.

  16. Enzymatic biodiesel production: Technical and economical considerations

    DEFF Research Database (Denmark)

    Munk Nielsen, Per; Brask, Jesper; Fjerbæk, Lene

    2008-01-01

    It is well documented in the literature that enzymatic processing of oils and fats for biodiesel is technically feasible. However, with very few exceptions, enzyme technology is not currently used in commercial-scale biodiesel production. This is mainly due to non-optimized process design...... and a lack of available costeffective enzymes. The technology to re-use enzymes has typically proven insufficient for the processes to be competitive. However, literature data documenting the productivity of enzymatic biodiesel together with the development of new immobilization technology indicates...... that enzyme catalysts can become cost effective compared to chemical processing. This work reviews the enzymatic processing of oils and fats into biodiesel with focus on process design and economy....

  17. Synthesis, characterization, DFT calculations and biological studies of Mn(II), Fe(II), Co(II) and Cd(II) complexes based on a tetradentate ONNO donor Schiff base ligand

    Science.gov (United States)

    Abdel-Rahman, Laila H.; Ismail, Nabawia M.; Ismael, Mohamed; Abu-Dief, Ahmed M.; Ahmed, Ebtehal Abdel-Hameed

    2017-04-01

    This study highlights synthesis and characterization of a tetradentate ONNO Schiff base ligand namely (1, 1‧- (pyridine-2, 3-dimethyliminomethyl) naphthalene-2, 2‧-diol) and hereafter denotes as "HNDAP″ and selected metal complexes including Mn(II), Fe(II), Co(II) and Cd(II) as a central metal. HNDAP was synthesized from 1:2 M ratio condensation of 2, 3-diaminopyridine and 2- hydroxy-1-naphthaldhyde, respectively. The stoichiometric ratios of the prepared complexes were estimated using complementary techniques such as; elemental analyses (-C, H, N), FT-IR, magnetic measurements and molar conductivity. Furthermore, their physicochemical studies were carried out using thermal TGA, DTA and kinetic-thermodynamic studies along with DFT calculations. The results of elemental analyses showed that these complexes are present in a 1:1 metal-to- ligand molar ratio. Moreover, the magnetic susceptibilities values at room temperature revealed that Mn(II), Fe(II) and Co(II) complexes are paramagnetic in nature and have an octahedral (Oh) geometry. In contrast, Cd(II) is diamagnetic and stabilizes in square planar sites. The molar conductivity measurements indicated that all complexes are nonelectrolytes in dimethyl formamide. Spectral data suggested that the ligand is as tetradentate and coordinated with Co(II) ion through two phenolic OH and two azomethine nitrogen. However, for Mn(II), Fe(II) and Cd(II) complexes, the coordination occurred through two phenolic oxygen and two azomethine nitrogen with deprotonation of OH groups. The proposed chemical structures have been validated by quantum mechanics calculations. Antimicrobial activities of both the HNDAP Schiff base ligand and its metal complexes were tested against strains of Gram (-ve) E. coli and Gram (+ve) B. subtilis and S. aureus bacteria and C. albicans, A. flavus and T. rubrum fungi. All the prepared compounds showed good results of inhibition against the selected pathogenic microorganisms. The investigated

  18. Enzymatic production of polysaccharides from gum tragacanth

    DEFF Research Database (Denmark)

    2014-01-01

    Plant polysaccharides, relating to the field of natural probiotic components, can comprise structures similar to human milk oligosaccharides. A method for enzymatic hydrolysis of gum tragacanth from the bush-like legumes of the genus Astragalus, using a combination of pectin hydrolases and a xylo......Plant polysaccharides, relating to the field of natural probiotic components, can comprise structures similar to human milk oligosaccharides. A method for enzymatic hydrolysis of gum tragacanth from the bush-like legumes of the genus Astragalus, using a combination of pectin hydrolases...

  19. Ancient DNA: extraction, characterization, molecular cloning, and enzymatic amplification.

    Science.gov (United States)

    Pääbo, S

    1989-03-01

    Several chemical and enzymatic properties were examined in the DNA extracted from dry remains of soft tissues that vary in age from 4 to 13,000 years and represent four species, including two extinct animals (the marsupial wolf and giant ground sloth). The DNA obtained was invariably of a low average molecular size and damaged by oxidative processes, which primarily manifest themselves as modifications of pyrimidines and sugar residues as well as baseless sites and intermolecular cross-links. This renders molecular cloning difficult. However, the polymerase chain reaction can be used to amplify and study short mitochondrial DNA sequences that are of anthropological and evolutionary significance. This opens up the prospect of performing diachronical studies of molecular evolutionary genetics.

  20. Synthesis, Characterization and DNA-Binding Properties of The Novel Mononuclear Zn(II, Cd(II, and Mn(II Complexes with Pantoprazole.

    Directory of Open Access Journals (Sweden)

    Wessam N. El-Sayed

    2016-04-01

    Full Text Available A   novel   mononuclear   Mn(II,   Zn(II   and   Cd(II   complexes of pantoprazole   (PA   was synthesized  and characterized  by elemental analysis,  molar conductivity,  magnetic susceptibility   measurements,   IR,  UV-visible  spectral  studies,  and  thermal  analysis.  The electronic spectra along with magnetic data suggest octahedral geometry for Mn(II, Zn(II and Cd(II complexes.  PA acts as an anionic bi-dentate ligand being coordinated by (S=O oxygen and benzimdazolyl nitrogen atoms. The interaction of the complexes with calf thymus DNA (CT-DNA was monitored by blue shift and hyperchromism in the UV-vis spectra. The observed  intrinsic  binding  constants  together  with  structural  analysis  of  the  complexes indicate  the groove  binding. The binding constants were determined at 303°K, 308°K and 313°K.  A thermodynamic analysis showed that the reaction is spontaneous with ΔG being negative. The enthalpy ΔH and the entropy ΔS of reactions were all determined.

  1. Economical synthesis of silver nanoparticles using leaf extract of Acalypha hispida and its application in the detection of Mn(II ions

    Directory of Open Access Journals (Sweden)

    R. Sithara

    2017-11-01

    Full Text Available This study was focused on the synthesis of silver nanoparticles using Acalypha hispida leaf extract and the characterization of the particles using UV–Vis spectroscopy, XRD, FT-IR, and TEM. The results showed the formation of silver nanoparticles, crystalline in nature, with an average size of 20–50 nm. The leaf extract components were analyzed with GC–MS and exhibited a high content of Phytol (40.52%, n-Hexadecanoic acid (9.67%, 1,2,3-Benzenetriol (7.04%, α-d-Mannofuranoside methyl (6.22%, and d-Allose (4.45%. The optimization and statistical investigation of reaction parameters were studied and maximum yield with suitable properties of silver nanoparticles was obtained at leaf extract volume (0.5 mL, the concentration of silver nitrate (1.75 mM, and reaction temperature (50 °C. The method of detecting Mn2+ ions using the colloidal silver nanoparticles was discussed. The minimum and maximum detection limit were found to be 50 and 200 µM of Mn(II ions, respectively. Thus, the obtained results encourage the use of economical synthesis of silver nanoparticles in the development of nanosensors to detect the pollutants present in industrial effluents.

  2. Application of modified multiwalled carbon nanotubes as a sorbent for simultaneous separation and preconcentration trace amounts of Au(III) and Mn(II)

    International Nuclear Information System (INIS)

    Shamspur, Tayebeh; Mostafavi, Ali

    2009-01-01

    A solid phase extraction procedure is proposed for simultaneous separation and preconcentration trace amounts of Au(III) and Mn(II) in an aqueous medium by using a column of multiwalled carbon nanotubes modified with the analytical reagent N,N'-bis(2-hydroxybenzylidene)-2,2'(aminophenylthio)ethane. An implementation, it was found that the sorption is quantitative in the pH range 5.0-7.5, whereas quantitative desorption occurs instantaneously with 4.0 mL of 0.1 mol L -1 Na 2 S 2 O 3. Selected elements were also determined by flame atomic absorption spectrometry. Linearity was maintained between 0.2 ng mL -1 to 25 μg mL -1 for gold and 0.08 ng mL -1 to 5 μg mL -1 for manganese in the original solution. Various parameters such as the effect of pH, flow rate, type and amount of eluent, breakthrough volume and interference of a large number of anions and cations on the recovery of the selected ions was studied. Under optimum conditions, the detection limits (3 s, n = 10) for analytes were 0.03 ng mL -1 (gold) and 0.01 ng mL -1 (manganese). The method was successfully applied for separation and determination of gold and manganese ions in water and standard samples.

  3. The effects of some compounds of Mn(II and Zn(II on the multiplication of wine yeast and biosynthesis of carbohydrates in the biomass

    Directory of Open Access Journals (Sweden)

    Agafia USATÎI

    2010-11-01

    Full Text Available The aim of investigation was to establish the influence of sulphates, acetates and coordination compounds of Mn(II and Zn(II as stimulators of the multiplication and growth of wine yeasts strain Saccharomyces cerevisiae CNMN-Y-20 and inducers of carbohydrate biosynthesis in biomass with the following elaboration of new procedures for directed carbohydrate biosynthesis. The study has been revealed that compounds MnSO4•4H2O, [Mn2Ac(2PyTCH-1,5-Bis(piridintiocarbohidrazid-dimanganese-acetate] and ZnLP-2 in optimal concentrations can be recommended as effective regulators of the yeast Saccharomyces cerevisiae CNMN-Y-20 multiplications, as well as compounds [Mn(Gly2]Cl2, (CH3COO2Zn and ZnLP-2 in established concentrations - of the carbohydrates biosynthesis in the biomass of studied wine yeast strain. Stimulatory properties of studied compounds of Mn2+ and Zn2+ on carbohydrate biosynthesis in biomass of Saccharomyces cerevisiae CNMN-Y-20 can be explained both by the action of metal and by the nature of the ligand. The obtained biomass of wine yeast strain with high content of carbohydrates can be utilized for the obtaining of new bioproducts with the following application in the field of medicine and cosmetology.

  4. Preparation and characterization of electrically conducting polypyrrole Sn(IV phosphate cation-exchanger and its application as Mn(II ion selective membrane electrode

    Directory of Open Access Journals (Sweden)

    A.A. Khan

    2011-10-01

    Full Text Available Polypyrrole Sn(IV phosphate, an organic–inorganic composite cation-exchanger was synthesized via sol-gel mixing of an organic polymer, polypyrrole, into the matrices of the inorganic precipitate of Sn(IV phosphate. The physico-chemical properties of the material were determined using Atomic Absorption Spectrometry (AAS, CHN elemental analysis (inductively coupled plasma mass spectrometry, ICP-MS, UV–VIS spectrophotometry, FTIR (Fourier Transform Infra-Red, SEM (Scanning Electron Microscopy, TGA–DTA (Thermogravimetric Analysis–Differential Thermal Analysis, and XRD (X-ray diffraction. Ion-exchange behavior was observed to characterize the material. On the basis of distribution studies, the material was found to be highly selective for toxic heavy metal ion Mn2+. Due to its selective nature, the material was used as an electroactive component for the construction of an ion-selective membrane electrode. The proposed electrode shows fairly good discrimination of mercury ion over several other inorganic ions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations for Mn(II in water.

  5. Hydrolysis of Miscanthus for bioethanol production using dilute acid presoaking combined with wet explosion pre-treatment and enzymatic treatment

    DEFF Research Database (Denmark)

    Sørensen, Annette; Teller, Philip Johan; Hilstrøm, Troels

    2008-01-01

    xylose prior to wet explosion. The acid presoaking extracted 63.2% xylose and 5.2% glucose. Direct enzymatic hydrolysis of the presoaked biomass was found to give only low sugar yields of 24-26% glucose. Wet explosion is a pre-treatment method that combines wet-oxidation and steam explosion. The effect...... of wet explosion on non-presoaked and presoaked Miscanthus was investigated using both atmospheric air and hydrogen peroxide as the oxidizing agent. All wet explosion pre-treatments showed to have a disrupting effect on the lignocellulosic biomass, making the sugars accessible for enzymatic hydrolysis......Miscanthus is a high yielding bioenergy crop. In this study we used acid presoaking, wet explosion, and enzymatic hydrolysis to evaluate the combination of the different pre-treatment methods for bioethanol production with Miscanthus. Acid presoaking is primarily carried out in order to remove...

  6. Dynamics of the enzymatic antioxidants during experimental caprine coccidiosis.

    Science.gov (United States)

    Rakhshandehroo, E; Razavi, S M; Nazifi, S; Farzaneh, M; Mobarraei, N

    2013-04-01

    Caprine coccidiosis, caused by coccidian parasites from genus Eimeria, is considered as one of the most common and significant diseases in goats worldwide. The aim of this experiment was to investigate the responses of the enzymatic antioxidant systems during experimental coccidiosis. For this purpose, 20 newborn kids were selected. Ten were infected with sporulated oocysts of the most pathogenic species of Eimeria, and the remainder served as the control. Blood samples were taken at 0 (before inoculation), 3, 7, 14, 21, 28, and 35 days post-infection (dpi), and antioxidant-oxidant-related parameters were measured. Our data showed that the activities of the main erythrocyte antioxidant enzymes revealed significant declines at 7 dpi. These decreases were more evident at 14 to 21 dpi and then gradually enhanced to the normal values until 35 dpi; however, total antioxidant capacity revealed a remarkable decrease at 7 dpi and remained on the same level toward the end of the study. By contrast, serum levels of malondialdehyde (a biomarker of lipid peroxidation) and total homocysteine significantly increased at 21 and 14, 21, and 28 dpi, respectively. These observations suggest that caprine coccidiosis can impair the major antioxidant systems leading to remarkable oxidative damages during the infection. Furthermore, oxidative injuries could have a considerable linkage to the pathogenesis of Eimeria parasites.

  7. Enzymatic treatment of sulfonated aromatic amines generated from reductive degradation of reactive azo dyes.

    Science.gov (United States)

    Biswas, Mousumi Mani; Taylor, Keith E; Bewtra, Jatinder K; Biswas, Nihar

    2007-04-01

    Anaerobic degradation, an effective treatment process of textile industry effluent, generates sulfonated aromatic amines, which are carcinogenic, mutagenic, and resistant to microbial degradation. These aromatic amines can be effectively removed by oxidative polymerization catalyzed by peroxidase enzyme. The amines, generated in this study from the anaerobic reduction by zero-valent iron of two reactive azo dyes (Reactive Red 2 [RR2] and Reactive Black 5 [RB5]), were successfully removed (90%) by Arthromyces ramosus peroxidase (ARP). For better understanding of the process, enzymatic treatment of two model compounds, diphenylamine (DPA) and 2-amino-8-naphthol-3,6-disulfonic acid (ANDSA), were also studied. Diphenylamine has a similar diarylamine bond as RR2. The ANDSA has a similar structure as the dye reduction products. The secondary amine bond in DPA and RR2 were oxidized by ARP. Enzymatic reaction of sulfonated aromatic amines generated soluble colored compounds, which were removed by coagulant. Optimum reaction parameters were also determined.

  8. Enzymatic activity of the cellulolytic complex produced by trichoderma reesei. Enzymatic hydrolysis of cellulose

    International Nuclear Information System (INIS)

    Alfonsel Jaen, M.; Negro, M.J.; Saez, R.; Martin Moreno, C.

    1986-01-01

    The enzymatic activity characterization of the cellulolytic complex obtained from Trichoderma reese QM 9414 and the influence of the enzymatic hydrolysis conditions on the hydrolysis yield are studied. Pure cellulose and native or alkali pretreated biomass from Onopordum nervosum have been used as substrates. The values of pH, temperature, substrate concentration and enzyme-substrate ratio for the optimum activity of that complex, evaluated as glucose and reducing sugars productions, have been selected. Previous studies on enzymatic hydrolysis of O. nervosum have shown a remarkable effect of the alkaline pretreatments on the final hydrolysis yield. (author). 10 figs.; 10 refs

  9. Enzymatic activity of the cellulolytic complex produced by Trichoderma reesei. Enzymatic hydrolysis of cellulose

    International Nuclear Information System (INIS)

    Alfonsel J, M.; Negro A, M. J.; Saez A, R.; Martin M, C.

    1986-01-01

    The enzymatic activity characterization of the cellulolytic complex obtained from Trichoderma reesei QM 9414 and the influence of the enzymatic hydrolysis conditions on the hydrolysis yield are studied. Pure cellulose and native or alkali pretreated biomass Onopordum nervosum have been used as substrates. The values of pH, temperature, substrate concentration and enzyme-substrate ratio for the optimum activity of that complex, evaluated as glucose and reducing sugars production, have been selected. Previous studies on enzymatic hydrolysis of 0. nervosum have shown a remarkable effect of the alkaline pretreatments on the final hydrolysis yield. (Author) 10 refs

  10. Ultrasonic acceleration of enzymatic processing of cotton

    Science.gov (United States)

    Enzymatic bio-processing of cotton generates significantly less hazardous wastewater effluents, which are readily biodegradable, but it also has several critical shortcomings that impede its acceptance by industries: expensive processing costs and slow reaction rates. It has been found that the intr...

  11. Enzymatic hydrolysis of pretreated soybean straw

    International Nuclear Information System (INIS)

    Xu Zhong; Wang Qunhui; Jiang Zhaohua; Yang Xuexin; Ji Yongzhen

    2007-01-01

    In order to produce lactic acid, from agricultural residues such as soybean straw, which is a raw material for biodegradable plastic production, it is necessary to decompose the soybean straw into soluble sugars. Enzymatic hydrolysis is one of the methods in common use, while pretreatment is the effective way to increase the hydrolysis rate. The optimal conditions of pretreatment using ammonia and enzymatic hydrolysis of soybean straw were determined. Compared with the untreated straw, cellulose in straw pretreated by ammonia liquor (10%) soaking for 24 h at room temperature increased 70.27%, whereas hemicellulose and lignin in pretreated straw decreased to 41.45% and 30.16%, respectively. The results of infrared spectra (IR), scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis also showed that the structure and the surface of the straw were changed through pretreatment that is in favor of the following enzymatic hydrolysis. maximum enzymatic hydrolysis rate of 51.22% was achieved at a substrate concentration of 5% (w/v) at 50 deg. C and pH 4.8 using cellulase (50 fpu/g of substrate) for 36 h

  12. Starch facilitates enzymatic wheat gluten hydrolysis

    NARCIS (Netherlands)

    Hardt, N.A.; Boom, R.M.; Goot, van der A.J.

    2015-01-01

    Wheat gluten can be hydrolyzed by either using (vital) wheat gluten or directly from wheat flour. This study investigates the influence of the presence of starch, the main component of wheat, on enzymatic wheat gluten hydrolysis. Wheat gluten present in wheat flour (WFG) and vital wheat gluten (VWG)

  13. Enzymatic assay for methotrexate in erythrocytes

    DEFF Research Database (Denmark)

    Schrøder, H; Heinsvig, E M

    1985-01-01

    Methotrexate (MTX) accumulates in erythrocytes in MTX-treated patients. We present a modified enzymatic assay measuring MTX concentrations between 10 and 60 nmol/l in erythrocytes, adapted for a centrifugal analyser (Cobas Bio). About 40 patient's samples could be analysed within 1 h. The detection...

  14. Enzymatic production of human milk oligosaccharides

    DEFF Research Database (Denmark)

    Guo, Yao

    Enzymatic treatment of biomass is an environmentally friendly method to obtain a range of value- added products, such as biofuels, animal feed or food ingredients. The objective of this PhD study was to biocatalytically produce biofunctional food ingredients – human milk oligosaccharides decorate...

  15. A comparative genomic analysis of the oxidative enzymes potentially involved in lignin degradation by Agaricus bisporus

    Science.gov (United States)

    Harshavardhan Doddapaneni; Venkataramanan Subramanian; Bolei Fu; Dan Cullen

    2013-01-01

    The oxidative enzymatic machinery for degradation of organic substrates in Agaricus bisporus (Ab) is at the core of the carbon recycling mechanisms in this fungus. To date, 156 genes have been tentatively identified as part of this oxidative enzymatic machinery, which includes 26 peroxidase encoding genes, nine copper radical oxidase [including three...

  16. Improved enzymatic production of phenolated glycerides through alkyl phenolate intermediate

    DEFF Research Database (Denmark)

    Yang, Zhiyong; Feddern, Vivian; Glasius, Marianne

    2011-01-01

    This work reported a novel approach for synthesis of dihydrocaffoylated glycerides, consisting of 2 steps: enzymatic synthesis of octyl dihydrocaffeate (as a synthetic intermediate) from octanol and dihydrocaffeic acid (DHCA), and enzymatic interesterification of triglycerides with octyl dihydroc...

  17. Impact of environmental chemistry on mycogenic Mn oxide minerals

    Science.gov (United States)

    Santelli, C. M.; Farfan, G. A.; Post, A.; Post, J. E.

    2012-12-01

    Manganese (Mn) oxide minerals are ubiquitous in aquatic and terrestrial environments and their presence can have broad environmental consequences. In particular, Mn oxides scavenge nutrients and metals, degrade complex organics, and oxidize a variety of inorganic contaminants. The "reactivity" of Mn oxides, however, is highly dependent upon crystallite size, composition, and structure, which are largely determined by environmental factors such as solution chemistry. It is has been suggested that most Mn oxides in terrestrial and aquatic environments are formed by microbial activity; indeed, a diversity of Mn(II)-oxidizing bacteria and fungi have been isolated and their mineral byproducts are consistent with those observed in natural systems. Previous studies showed that Mn(II)-oxidizing Ascomycete fungi produce highly-disordered, nanocrystalline Mn oxides that are structurally similar to synthetic δ-MnO2 or natural vernadite. Unlike related studies with Mn-oxidizing bacteria, Mn oxides produced by these fungi did not "age" or transform to more crystalline mineral phases with time. We hypothesize that fungal growth conditions, in particular the low concentration of cations, are inhibiting secondary mineral formation. The overall goal of this research is to examine the structure and speciation of fungally-precipitated Mn oxides with respect to fungal species, time, and concentration of soluble Mn(II), Na, and Ca - three environmentally relevant cations that promote the transformation of δ-MnO2 to more crystalline mineral phases such as feitknechtite, birnessite, or ranciéite. For this study, we examined the Mn oxides formed by different species of Mn(II)-oxidizing fungi (Pyrenochaeta sp., Stagonospora sp., Plectosphaerella cucumerina., and Acremonium strictum). Isolates were grown for 8 or 16 days in a nutrient lean media consisting of yeast extract, trace elements and 0.2 mM MnCl2 supplemented with varying concentrations of Na, Ca, or Mn(II) compounds. The

  18. Localized cranial hyperostosis of meningiomas: a result of neoplastic enzymatic activity?

    DEFF Research Database (Denmark)

    Heick, A.; Mosdal, C.; Klinken, Leif

    1993-01-01

    Neuropathology, alkaline phosphatase, cranial hyperostosis, meningioma, ossifying enzymatic activity......Neuropathology, alkaline phosphatase, cranial hyperostosis, meningioma, ossifying enzymatic activity...

  19. Biogenic precipitation of manganese oxides and enrichment of heavy metals at acidic soil pH

    Science.gov (United States)

    Mayanna, Sathish; Peacock, Caroline L.; Schäffner, Franziska; Grawunder, Anja; Merten, Dirk; Kothe, Erika; Büchel, Georg

    2014-05-01

    The precipitation of biogenic Mn oxides at acidic pH is rarely reported and poorly understood, compared to biogenic Mn oxide precipitation at near neutral conditions. Here we identified and investigated the precipitation of biogenic Mn oxides in acidic soil, and studied their role in the retention of heavy metals, at the former uranium mining site of Ronneburg, Germany. The site is characterized by acidic pH, low carbon content and high heavy metal loads including rare earth elements. Specifically, the Mn oxides were present in layers identified by detailed soil profiling and within these layers pH varied from 4.7 to 5.1, Eh varied from 640 to 660 mV and there were enriched total metal contents for Ba, Ni, Co, Cd and Zn in addition to high Mn levels. Using electron microprobe analysis, synchrotron X-ray diffraction and X-ray absorption spectroscopy, we identified poorly crystalline birnessite (δ-MnO2) as the dominant Mn oxide in the Mn layers, present as coatings covering and cementing quartz grains. With geochemical modelling we found that the environmental conditions at the site were not favourable for chemical oxidation of Mn(II), and thus we performed 16S rDNA sequencing to isolate the bacterial strains present in the Mn layers. Bacterial phyla present in the Mn layers belonged to Firmicutes, Actinobacteria and Proteobacteria, and from these phyla we isolated six strains of Mn(II) oxidizing bacteria and confirmed their ability to oxidise Mn(II) in the laboratory. The biogenic Mn oxide layers act as a sink for metals and the bioavailability of these metals was much lower in the Mn layers than in adjacent layers, reflecting their preferential sorption to the biogenic Mn oxide. In this presentation we will report our findings, concluding that the formation of natural biogenic poorly crystalline birnessite can occur at acidic pH, resulting in the formation of a biogeochemical barrier which, in turn, can control the mobility and bioavailability of heavy metals in

  20. Synthesis, structural characterization and evaluation of catalytic and antimicrobial properties of new mononuclear Ag(I), Mn(II), Cu(II) and Pt(IV) complexes

    Science.gov (United States)

    Ali, Omyma A. M.; Abd El-Wahab, Zeinab H.; Ismail, Basmh A.

    2017-07-01

    New mononuclear complexes of composition [AgL(H2O)2]NO3·H2O, [MnL2Cl(H2O)]Cl.3½H2O, [CuL2Cl2].½H2O and [PtLCl3(H2O)]Cl·2H2O {where L was 1-(2-furylmethylene)-N-(3-phenylallylidene) methanamine} were synthesized and characterized by different techniques. From the analytical data, the stoichiometry of the complexes were 1:1 for Ag(I) and Pt(IV) complexes and 1:2 (M:L) for Mn(II) and Cu(II) complexes. Conductance data indicated that all complexes are electrolytic in nature while, Cu(II) complex was non-electrolyte. Spectroscopic data suggested that the ligand behaves as a neutral bidentate ligand towards the central metal ion with azomethine nitrogen and furan oxygen atoms as coordination sites. Tetrahedral structure has been proposed for Ag(I) complex, whereas the other complexes possess six coordinated octahedral geometry. TG-DTG study was done to track the thermal behavior of the complexes and the thermodynamic parameters were computed from the thermal data using Coats - Redfern method. The catalytic activity of the metal complexes was evaluated in the decomposition reaction of hydrogen peroxide at 313-333 K temperature range. The data reveal that metal complexes are effective in catalyzing the hydrogen peroxide decomposition and the decomposition percentage increased with temperature. The agar well diffusion technique was used to test the growth inhibition of the ligand and its complexes against different species of bacteria and fungi. The metal complexes are more potent in inhibiting the growth of microorganisms than the ligand and in some cases, the complexes were closed to and more active than the standard species.

  1. Zn(II, Mn(II and Sr(II Behavior in a Natural Carbonate Reservoir System. Part II: Impact of Geological CO2 Storage Conditions

    Directory of Open Access Journals (Sweden)

    Auffray B.

    2016-07-01

    Full Text Available Some key points still prevent the full development of geological carbon sequestration in underground formations, especially concerning the assessment of the integrity of such storage. Indeed, the consequences of gas injection on chemistry and petrophysical properties are still much discussed in the scientific community, and are still not well known at either laboratory or field scale. In this article, the results of an experimental study about the mobilization of Trace Elements (TE during CO2 injection in a reservoir are presented. The experimental conditions range from typical storage formation conditions (90 bar, supercritical CO2 to shallower conditions (60 and 30 bar, CO2 as gas phase, and consider the dissolution of the two carbonates, coupled with the sorption of an initial concentration of 10−5 M of Zn(II, and the consequent release in solution of Mn(II and Sr(II. The investigation goes beyond the sole behavior of TE in the storage conditions: it presents the specific behavior of each element with respect to the pressure and the natural carbonate considered, showing that different equilibrium concentrations are to be expected if a fluid with a given concentration of TE leaks to an upper formation. Even though sorption is evidenced, it does not balance the amount of TE released by the dissolution process. The increase in porosity is clearly evidenced as a linear function of the CO2 pressure imposed for the St-Emilion carbonate. For the Lavoux carbonate, this trend is not confirmed by the 90 bar experiment. A preferential dissolution of the bigger family of pores from the preexisting porosity is observed in one of the samples (Lavoux carbonate while the second one (St-Emilion carbonate presents a newly-formed family of pores. Both reacted samples evidence that the pore network evolves toward a tubular network type.

  2. An enzymatic method for removal of phenol from industrial effluent

    Energy Technology Data Exchange (ETDEWEB)

    Singh, N.; Singh, J. [DN College, Meerut (India). Dept. of Chemistry

    2002-07-01

    Phenols occur in wastewater of a number of industries, such as high temperature coal conversion, petroleum refining, resin and plastic, wood and dye industries, etc. It can be toxic when present at elevated levels and is known to be carcinogenous. An enzymatic method for removal of phenols from industrial wastewater, using turnip peroxidase, has been developed. Phenol-containing industrial wastewater was treated with immobilized turnip peroxidase in the presence of hydrogen peroxide. In the reaction, a number of phenols are oxidized to form the corresponding free radicals in the presence of hydrogen peroxide as an oxidant. Free radicals polymerize to form substances that are less soluble in water than the original substances. The precipitates were removed by conventional methods and residual phenol was estimated. The present report describes the immobilization of turnip peroxidase on silica via covalent coupling, and its utility in phenol removal. A comparative study was also carried out with other immobilization techniques, viz., calcium alginate entrapment, polyacrylamide gel entrapment, etc. Peroxidase, covalently bound to silica, showed 95% removal of phenol, whereas naphthol was removed up to 99%.

  3. Enzymatic production of ceramide from sphingomyelin

    DEFF Research Database (Denmark)

    Zhang, Long; Hellgren, Lars; Xu, Xuebing

    Ceramide is the key intermediate in the biosynthesis of all complex sphingolipids. Due to its major role in maintaining the water-retaining properties of the epidermis, ceramide is of great commercial potential in cosmetic and pharmaceuticals such as hair and skin care products. Currently, chemical...... synthesis of ceramide is a costly and time consuming process, and developments of alternative cost-efficient, high yield production methods are of great interest. In the present, the potential of producing ceramide through the enzymatic hydrolysis of sphingomyelin have been studied. Sphingomyelin, which...... contains a ceramide moiety, is a ubiquitous component of animal cell membranes, and dairy products or by-products is a rich source of sphingomyelin. It has been verified that enzymatic modification of sphingomyelin is a feasible approach for production of ceramide. The reaction system has been optimized...

  4. Production of MAG via enzymatic glycerolysis

    Science.gov (United States)

    Jamlus, Norul Naziraa Ahmad; Derawi, Darfizzi; Salimon, Jumat

    2015-09-01

    Enzymatic glycerolysis of a medium chain methyl ester, methyl laurate was performed using lipase Candida antarctica (Novozyme 435) for 6 hours at 55°C. The percentage of components mixture of product were determined by using gas chromatography technique. The enzymatic reaction was successfully produced monolaurin (45.9 %), dilaurin (47.1 %) and trilaurin (7.0 %) respectively. Thin layer chromatography (TLC) plate also showed a good separation of component spots. Fourier transformation infra-red (FTIR) spectrum showed the presence of ester carbonyl at wavenumber 1739.99 cm-1 and hydrogen bonded O-H at 3512.03 cm-1. The product is potentially to be used as emulsifier and additive in food industry, pharmaceutical, as well as antibacterial.

  5. The oxidative hypothesis of senescence

    Directory of Open Access Journals (Sweden)

    Gilca M

    2007-01-01

    Full Text Available The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g., those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc. This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal β -oxidation and respiratory burst of phagocytic cells, antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol, alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.

  6. Enzymatic depolymerization of lignin by laccases

    OpenAIRE

    Hamidi, Nor Hanimah

    2013-01-01

    More than half of platform petrochemicals are aromatic, whereas the only large-scale, naturally-occurring, renewable source of aromatics is lignin. Chemical depolymerization of lignin requires extreme conditions, and results in extensive destruction of the aromatic rings and/or char formation. By contrast, enzymatic lignin depolymerization occurs under mild conditions with retention of the aromatic nuclei. Therefore, laccase from Agaricus bisporus (LAB) and from Trametes versicolor (LTV) with...

  7. Regioselective enzymatic acylation ofN-acetylhexosamines

    Czech Academy of Sciences Publication Activity Database

    Simerská, Pavla; Pišvejcová, Andrea; Kuzma, Marek; Sedmera, Petr; Křen, Vladimír; Nicotra, S.; Riva, S.

    2004-01-01

    Roč. 29, - (2004), s. 219-225 ISSN 1381-1177 R&D Projects: GA ČR GA203/01/1018; GA MŠk OC D25.002 Grant - others:GA NATO(XX) LST.CLG.980125 Institutional research plan: CEZ:AV0Z5020903 Keywords : n-acetylhexosamines * regioselectivity * enzymatic acylation Subject RIV: EE - Microbiology, Virology Impact factor: 1.547, year: 2004

  8. Enzymatic Synthesis of Biobased Polyesters and Polyamides

    Directory of Open Access Journals (Sweden)

    Yi Jiang

    2016-06-01

    Full Text Available Nowadays, “green” is a hot topic almost everywhere, from retailers to universities to industries; and achieving a green status has become a universal aim. However, polymers are commonly considered not to be “green”, being associated with massive energy consumption and severe pollution problems (for example, the “Plastic Soup” as a public stereotype. To achieve green polymers, three elements should be entailed: (1 green raw materials, catalysts and solvents; (2 eco-friendly synthesis processes; and (3 sustainable polymers with a low carbon footprint, for example, (biodegradable polymers or polymers which can be recycled or disposed with a gentle environmental impact. By utilizing biobased monomers in enzymatic polymerizations, many advantageous green aspects can be fulfilled. For example, biobased monomers and enzyme catalysts are renewable materials that are derived from biomass feedstocks; enzymatic polymerizations are clean and energy saving processes; and no toxic residuals contaminate the final products. Therefore, synthesis of renewable polymers via enzymatic polymerizations of biobased monomers provides an opportunity for achieving green polymers and a future sustainable polymer industry, which will eventually play an essential role for realizing and maintaining a biobased and sustainable society.

  9. Microbial Enzymatic Degradation of Biodegradable Plastics.

    Science.gov (United States)

    Roohi; Bano, Kulsoom; Kuddus, Mohammed; Zaheer, Mohammed R; Zia, Qamar; Khan, Mohammed F; Ashraf, Ghulam Md; Gupta, Anamika; Aliev, Gjumrakch

    2017-01-01

    The renewable feedstock derived biodegradable plastics are important in various industries such as packaging, agricultural, paper coating, garbage bags and biomedical implants. The increasing water and waste pollution due to the available decomposition methods of plastic degradation have led to the emergence of biodegradable plastics and biological degradation with microbial (bacteria and fungi) extracellular enzymes. The microbes utilize biodegradable polymers as the substrate under starvation and in unavailability of microbial nutrients. Microbial enzymatic degradation is suitable from bioremediation point of view as no waste accumulation occurs. It is important to understand the microbial interaction and mechanism involved in the enzymatic degradation of biodegradable plastics under the influence of several environmental factors such as applied pH, thermo-stability, substrate molecular weight and/or complexity. To study the surface erosion of polymer film is another approach for hydrolytic degradation characteristion. The degradation of biopolymer is associated with the production of low molecular weight monomer and generation of carbon dioxide, methane and water molecule. This review reported the degradation study of various existing biodegradable plastics along with the potent degrading microbes (bacteria and fungi). Patents available on plastic biodegradation with biotechnological significance is also summarized in this paper. This paper assesses that new disposal technique should be adopted for the degradation of polymers and further research is required for the economical production of biodegradable plastics along with their enzymatic degradation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  10. Interactions between metal oxides and species of nitrogen and iodine in bioturbated marine sediments

    Science.gov (United States)

    Anschutz, Pierre; Sundby, Bjørn; Lefrançois, Lucie; Luther, George W.; Mucci, Alfonso

    2000-08-01

    By using a gold amalgam (Au/Hg) voltammetric microelectrode, we have measured simultaneously and with millimeter resolution the distributions of O 2, Mn(II), Fe(II), I(-I), and HS(-I) in bioturbated sediment cores from the Laurentian Trough. We also measured nitrate and ammonia in the pore water, total I and ascorbate- and HCl-extractable Fe and Mn in the solid-phase sediment, and fluxes of O 2, NO 3-, and NH 4+ across the sediment-water interface. The concentrations of O 2 and Mn(II) were below their respective detection limits of 3 and 5 μM between 4 and 12 mm depth, but a sharp iodide maximum occurred at the depth where upward diffusing Mn(II) was being removed. We propose that the iodide peak is maintained through the reduction of IO 3- by Mn(II), reoxidation of I(-I) to IO 3- in the oxic zone above the peak and oxidation to I 2 below where it is ultimately trapped by reaction with organic matter. The iodide production rate is sufficient to account for the oxidation of all of the upward diffusing Mn(II) by IO 3-. Nitrate plus nitrite (ΣNO 3) decreased to a minimum within 10 mm of the sediment-water interface, in agreement with flux measurements which showed ΣNO 3 uptake by the sediment. Below the minimum, ΣNO 3 rebounded, and reached a maximum at 40- to 50-mm depth. This rebound is attributed to the anaerobic oxidation of ammonia by manganese oxides. Fe(II) was always first detected below the anoxic ΣNO 3 maximum, and was accompanied by colloidal or complexed Fe(III). A sharp upward-directed ammonia gradient was recorded near the sediment-water interface, but no ammonia was released during the first 48 h of the incubations. If the ammonia removal were due to coupled bacterial nitrification-denitrification, more than one half of the total measured oxygen uptake (6.7 to 7.3 mmol/m 2/d) would be required, and more organic carbon would be oxidized by nitrate than by oxygen. This scenario is not supported by nitrate flux calculations. Alternatively, the

  11. The effects of iron(II) on the kinetics of arsenic oxidation and sorption on manganese oxides.

    Science.gov (United States)

    Wu, Yun; Li, Wei; Sparks, Donald L

    2015-11-01

    In this study, As(III) oxidation kinetics by a poorly-crystalline phyllomanganate (δ-MnO2) in the presence and absence of dissolved Fe(II) was investigated using stirred-flow and batch experiments. Chemically synthetic δ-MnO2 was reacted with four influent solutions, containing the same As(III) concentration but different Fe(II) concentrations, at pH 6. The results show an initial rapid As(III) oxidation by δ-MnO2, which is followed by an appreciably slow reaction after 8h. In the presence of Fe(II), As(III) oxidation is inhibited due to the competitive oxidation of Fe(II) as well as the formation of Fe(III)-(hydr)oxides on the δ-MnO2 surface. However, the sorption of As(III), As(V) and Mn(II) are increased, for the newly formed Fe(III)-(hydr)oxides provide additional sorption sites. This study suggests that the competitive oxidation of Fe(II) and consequently the precipitation of Fe(III) compounds on the δ-MnO2 surface play an important role in As(III) oxidation and As sequestration. Understanding these processes would be helpful in developing in situ strategies for remediation of As-contaminated waters and soils. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Oxidation as an important factor of protein damage: Implications for ...

    Indian Academy of Sciences (India)

    ... site-specific metal-catalysed protein oxidation), oxidation-dependent generation of protein hydroperoxides, carbonyl derivatives and protein–protein cross-linkages. Non-enzymatic glycoxidation (also known as Maillard reaction) as an important factor of protein damage, consequences of oxidative protein impairment and ...

  13. Fabrication of Nickel/nanodiamond/boron-doped diamond electrode for non-enzymatic glucose biosensor

    International Nuclear Information System (INIS)

    Dai, Wei; Li, Mingji; Gao, Sumei; Li, Hongji; Li, Cuiping; Xu, Sheng; Wu, Xiaoguo; Yang, Baohe

    2016-01-01

    Highlights: • Nanodiamonds (NDs) were electrophoretically deposited on the BDD film. • The NDs significantly extended the potential window. • Ni/NDs/BDD electrode was prepared by electrodeposition. • The electrode shows good catalytic activity for glucose oxidation. - Abstract: A stable and sensitive non-enzymatic glucose sensor was prepared by modifying a boron-doped diamond (BDD) electrode with nickel (Ni) nanosheets and nanodiamonds (NDs). The NDs were electrophoretically deposited on the BDD surface, and acted as nucleation sites for the subsequent electrodeposition of Ni. The morphology and composition of the modified BDD electrodes were characterized by field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The Ni nanosheet-ND modified BDD electrode exhibited good current response towards the non-enzymatic oxidation of glucose in alkaline media. The NDs significantly extended the potential window. The response to glucose was linear over the 0.2–1055.4-μM range. The limit of detection was 0.05 μM, at a signal-to-noise ratio of 3. The Ni nanosheet-ND/BDD electrode exhibited good selectivity, reproducibility and stability. Its electrochemical performance, low cost and simple preparation make it a promising non-enzymatic glucose sensor.

  14. Inhibiting mitochondrial β-oxidation selectively reduces levels of nonenzymatic oxidative polyunsaturated fatty acid metabolites in the brain.

    Science.gov (United States)

    Chen, Chuck T; Trépanier, Marc-Olivier; Hopperton, Kathryn E; Domenichiello, Anthony F; Masoodi, Mojgan; Bazinet, Richard P

    2014-03-01

    Schönfeld and Reiser recently hypothesized that fatty acid β-oxidation is a source of oxidative stress in the brain. To test this hypothesis, we inhibited brain mitochondrial β-oxidation with methyl palmoxirate (MEP) and measured oxidative polyunsaturated fatty acid (PUFA) metabolites in the rat brain. Upon MEP treatment, levels of several nonenzymatic auto-oxidative PUFA metabolites were reduced with few effects on enzymatically derived metabolites. Our finding confirms the hypothesis that reduced fatty acid β-oxidation decreases oxidative stress in the brain and β-oxidation inhibitors may be a novel therapeutic approach for brain disorders associated with oxidative stress.

  15. A combined chemical + enzymatic method to remove selected aromatics from aqueous streams

    International Nuclear Information System (INIS)

    Xu, X.; John, V.

    1993-01-01

    Aromatics are major pollutants found in aqueous environments and in sediments. While there are many chemical and biochemical processes to remove and/or destroy these contaminants, they have to be considered in light of the economics and the time-scales for treatment. We describe our initial work on a hybrid chemical + enzymatic technique to remove aromatics from aqueous stream. The aromatic is first converted to the corresponding phenol through classical Fenton type chemistry involving catalysis by Fe(II). The phenol is subsequently polymerized through an enzymatic mechanism, using horseradish peroxidase as the oxidative enzyme. The polymer is insoluble in water and can be easily recovered. In addition, such phenolic polymers are useful products with varied applications in coatings and resin technologies. Thus, the pollutants can be eventually converted to useful products

  16. Impact of lignins isolated from pretreated lignocelluloses on enzymatic cellulose saccharification

    DEFF Research Database (Denmark)

    Barsberg, Søren Talbro; Selig, Michael Joseph; Felby, Claus

    2013-01-01

    Lignins were enzymatically isolated from corn stover and wheat straw samples and subjected to hydrothermal or wet oxidation pretreatments for enzyme adsorption experimentations. Lignin contents of the isolates ranged from 26 to 71 % (w/w); cellulose ranged from 3 to 22 % (w/w); xylan from 0.7 to 6...... % (w/w) and ash was from 5.8 to 30 % (w/w). ATR-IR analyses indicated significant and similar levels of calcium in all lignin isolates. Commercial cellulase adsorption studies showed that the presence of these lignins had no significant impact on the total amount of adsorbed enzyme in cellulose...... and cellulose-lignin systems. Consequently, the presence of the lignins had minimal effect, if any, on enzymatic cellulose conversion. Furthermore, this result, coupled with significant calcium levels in the isolated lignins, supports previous work suggesting lignin-calcium complexes reduce enzyme...

  17. Enzymatic Hydrolysis of Alkaline Pretreated Coconut Coir

    Directory of Open Access Journals (Sweden)

    Akbarningrum Fatmawati

    2013-06-01

    Full Text Available The purpose of this research is to study the effect of concentration and temperature on the cellulose and lignin content, and the reducing sugars produced in the enzymatic hydrolysis of coconut coir. In this research, the coconut coir is pretreated using 3%, 7%, and 11% NaOH solution at 60oC, 80oC, and 100oC. The pretreated coir were assayed by measuring the amount of cellulose and lignin and then hydrolysed using Celluclast and Novozyme 188 under various temperature (30oC, 40oC, 50oC and pH (3, 4, 5. The hydrolysis results were assayed for the reducing sugar content. The results showed that the alkaline delignification was effective to reduce lignin and to increase the cellulose content of the coir. The best delignification condition was observed at 11% NaOH solution and 100oC which removed 14,53% of lignin and increased the cellulose content up to 50,23%. The best condition of the enzymatic hydrolysis was obtained at 50oC and pH 4 which produced 7,57 gr/L reducing sugar. © 2013 BCREC UNDIP. All rights reservedReceived: 2nd October 2012; Revised: 31st January 2013; Accepted: 6th February 2013[How to Cite: Fatmawati, A., Agustriyanto, R., Liasari, Y. (2013. Enzymatic Hydrolysis of Alkaline Pre-treated Coconut Coir. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 34-39 (doi:10.9767/bcrec.8.1.4048.34-39[Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4048.34-39] | View in  |

  18. Comparative performance of enzymatic and combined alkaline-enzymatic pretreatments on methane production from ensiled sorghum forage.

    Science.gov (United States)

    Rollini, Manuela; Sambusiti, Cecilia; Musatti, Alida; Ficara, Elena; Retinò, Isabella; Malpei, Francesca

    2014-12-01

    This study investigated the effect of enzymatic and combined alkaline-enzymatic pretreatments on chemical composition and methane production from ensiled sorghum forage. Four commercial enzymatic preparations were tested and the two yielding the highest sugars release were added to evaluate any hydrolytic effect on both untreated and alkaline pretreated samples. In the combined alkaline-enzymatic pretreatment trials, the highest sugar release was found with Primafast and BGL preparations (added at a final concentration 0.12 and 0.20 mL/g TS, respectively), with a total monomeric content of 12 and 6.5 g/L. Fibre composition analysis confirmed that the combined alkaline-enzymatic pretreatment led to cellulose (up to 32 %) and hemicelluloses (up to 56 %) solubilisation, compared to the enzymatic pretreatment alone. BMP tests were performed on both untreated and pretreated samples, and time courses of methane production were fitted. Both enzymatic and combined alkaline-enzymatic pretreatment led to a methane production increase (304 and 362 mL CH4/g VS), compared to that of untreated sorghum (265 mL CH4/g VS), as  +15 and  +37 %, respectively. Moreover, higher specific methane production rates, compared to that of untreated sorghum (20.31 mL CH4/g VS/d), were obtained by applying the enzymatic and combined alkaline-enzymatic pretreatment (33.94 and 31.65 mL CH4/g VS/d), respectively.

  19. Isothermal calorimetry of enzymatic biodiesel reaction

    DEFF Research Database (Denmark)

    Fjerbæk Søtoft, Lene; Westh, Peter; Christensen, Knud Villy

    2010-01-01

      Isothermal calorimetry ITC has been used to investigate enzymatic biodiesel production. The transesterification of rapeseed oil with methanol and ethanol was catalyzed by the immobilized lipase Novozym 435 at 40°C. The ITC-experiments clearly demonstrate the possibilities of investigating complex...... and composition change in the system, the heat of reaction at 40°C for the two systems has been determined to -9.8 ± 0.9 kJ/mole biodiesel formed from rapeseed oil and methanol, and - 9.3 ± 0.7 kJ/mole when rapeseed oil and ethanol is used....

  20. Enzymatic Ligation of Large Biomolecules to DNA

    DEFF Research Database (Denmark)

    Sørensen, Rasmus Schøler; Okholm, Anders Hauge; Schaffert, David Henning

    2013-01-01

    application. However, conjugation of DNA to large molecular components using classical chemistries often suffers from suboptimal yields. Here, we report the use of terminal deoxynucleotidyl transferase (TdT) for direct enzymatic ligation of native DNA to nucleotide triphosphates coupled to proteins and other...... large macromolecules. We demonstrate facile synthesis routes for a range of NTP-activated macromolecules and subsequent ligation to the 3′ hydroxyl group of oligodeoxynucleotides using TdT. The reaction is highly specific and proceeds rapidly and essentially to completion at micromolar concentrations...

  1. Diversity of Mn oxides produced by Mn(II)-oxidizing fungi

    Science.gov (United States)

    Santelli, Cara M.; Webb, Samuel M.; Dohnalkova, Alice C.; Hansel, Colleen M.

    2011-05-01

    Manganese (Mn) oxides are environmentally abundant, highly reactive mineral phases that mediate the biogeochemical cycling of nutrients, contaminants, carbon, and numerous other elements. Despite the belief that microorganisms (specifically bacteria and fungi) are responsible for the majority of Mn oxide formation in the environment, the impact of microbial species, physiology, and growth stage on Mn oxide formation is largely unresolved. Here, we couple microscopic and spectroscopic techniques to characterize the Mn oxides produced by four different species of Mn(II)-oxidizing Ascomycete fungi ( Plectosphaerella cucumerina strain DS2psM2a2 , Pyrenochaeta sp. DS3sAY3a, Stagonospora sp. SRC1lsM3a, and Acremonium strictum strain DS1bioAY4a) isolated from acid mine drainage treatment systems in central Pennsylvania. The site of Mn oxide formation varies greatly among the fungi, including deposition on hyphal surfaces, at the base of reproductive structures (e.g., fruiting bodies), and on envisaged extracellular polymers adjacent to the cell. The primary product of Mn(II) oxidation for all species growing under the same chemical and physical conditions is a nanoparticulate, poorly-crystalline hexagonal birnessite-like phase resembling synthetic δ-MnO 2. The phylogeny and growth conditions (planktonic versus surface-attached) of the fungi, however, impact the conversion of the initial phyllomanganate to more ordered phases, such as todorokite ( A. strictum strain DS1bioAY4a) and triclinic birnessite ( Stagonospora sp. SRC1lsM3a). Our findings reveal that the species of Mn(II)-oxidizing fungi impacts the size, morphology, and structure of Mn biooxides, which will likely translate to large differences in the reactivity of the Mn oxide phases.

  2. Unraveling the mechanism responsible for the contrasting tolerance of Synechocystis and Synechococcus to Cr(VI): Enzymatic and non-enzymatic antioxidants

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Alka [Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Ballal, Anand, E-mail: aballal@barc.gov.in [Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 40085 (India)

    2015-07-15

    Highlights: • Cr(VI) accumulation generates higher ROS in Synechocystis than in Synechococcus. • Synechococcus exhibits better photosynthetic activity in response to Cr(VI). • Synechococcus has higher enzymatic/non-enzymatic antioxidants than Synechocystis. • Synechococcus shows better tolerance to other oxidative stresses than Synechocystis. • Differential detoxification of ROS is responsible for the contrasting tolerance to Cr(VI) - Abstract: Two unicellular cyanobacteria, Synechocystis and Synechococcus, showed contrasting tolerance to Cr(VI); with Synechococcus being 12-fold more tolerant than Synechocystis to potassium dichromate. The mechanism responsible for this differential sensitivity to Cr(VI) was explored in this study. Total content of photosynthetic pigments as well as photosynthetic activity decreased at lower concentration of Cr(VI) in Synechocystis as compared to Synechococcus. Experiments with {sup 51}Cr showed Cr to accumulate intracellularly in both the cyanobacteria. At lower concentrations, Cr(VI) caused excessive ROS generation in Synechocystis as compared to that observed in Synechococcus. Intrinsic levels of enzymatic antioxidants, i.e., superoxide dismutase, catalase and 2-Cys-peroxiredoxin were considerably higher in Synechococcus than Synechocystis. Content of total thiols (both protein as well as non-protein) and reduced glutathione (GSH) was also higher in Synechococcus as compared to Synechocystis. This correlated well with higher content of carbonylated proteins observed in Synechocystis than Synechococcus. Additionally, in contrast to Synechocystis, Synechococcus exhibited better tolerance to other oxidative stresses like high intensity light and H{sub 2}O{sub 2}. The data indicate that the disparity in the ability to detoxify ROS could be the primary mechanism responsible for the differential tolerance of these cyanobacteria to Cr(VI)

  3. Lactose hydrolysis in an enzymatic membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, B.; Huyghebaert, A.

    1987-10-01

    The enzymatic hydrolysis of lactose in whey permeate with subsequent recuperation of Saccharomyces lactis lactase by means of ultrafiltration was investigated. In whey permeate, S. lactis lactase shows maximal activity at pH 6.5; the optimal temperature was found to be 45/sup 0/C and is limited by strong thermal inactivation beyond this temperature. High activity combined with acceptable thermal inactivation (< 10% after 5 h incubation) was established at 30/sup 0/C. S. lactis lactase also displays considerable activity at low temperature (5/sup 0/C). Enzyme stability is reduced drastically by demineralisation: addition of low concentrations of manganese ions (10/sup -3/ M) considerably enhances stability. Using a DDS Lab-Unit 35 fitted with GR61PP polysulphon membranes (cut-off: 20.000), pilot scale experiments were carried out (pH 6.5; 30/sup 0/C) in which whey permeate was hydrolyzed to a degree of hydrolysis of 82% minimum. Enzyme recuperation amounted to 96.5% per batch, all enzyme activity loss being due to thermal inactivation. Microbiological examination of the enzymatic membrane reactor showed that growth of mcicroorganisms can largely be suppressed by working at lower temperature (5/sup 0/C). Eventually, 50 ppm H/sub 2/O/sub 2/ or sterile filtration will adequately solve microbiological problems without affecting enzyme activity.

  4. Mapping the Reaction Coordinates of Enzymatic Defluorination

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Peter W.Y.; Yakunin, Alexander F.; Edwards, Elizabeth A.; Pai, Emil F. (Toronto)

    2011-09-28

    The carbon-fluorine bond is the strongest covalent bond in organic chemistry, yet fluoroacetate dehalogenases can readily hydrolyze this bond under mild physiological conditions. Elucidating the molecular basis of this rare biocatalytic activity will provide the fundamental chemical insights into how this formidable feat is achieved. Here, we present a series of high-resolution (1.15-1.80 {angstrom}) crystal structures of a fluoroacetate dehalogenase, capturing snapshots along the defluorination reaction: the free enzyme, enzyme-fluoroacetate Michaelis complex, glycolyl-enzyme covalent intermediate, and enzyme-product complex. We demonstrate that enzymatic defluorination requires a halide pocket that not only supplies three hydrogen bonds to stabilize the fluoride ion but also is finely tailored for the smaller fluorine halogen atom to establish selectivity toward fluorinated substrates. We have further uncovered dynamics near the active site which may play pivotal roles in enzymatic defluorination. These findings may ultimately lead to the development of novel defluorinases that will enable the biotransformation of more complex fluorinated organic compounds, which in turn will assist the synthesis, detoxification, biodegradation, disposal, recycling, and regulatory strategies for the growing markets of organofluorines across major industrial sectors.

  5. Enzymatic deconstruction of xylan for biofuel production

    Science.gov (United States)

    DODD, DYLAN; CANN, ISAAC K. O.

    2010-01-01

    The combustion of fossil-derived fuels has a significant impact on atmospheric carbon dioxide (CO2) levels and correspondingly is an important contributor to anthropogenic global climate change. Plants have evolved photosynthetic mechanisms in which solar energy is used to fix CO2 into carbohydrates. Thus, combustion of biofuels, derived from plant biomass, can be considered a potentially carbon neutral process. One of the major limitations for efficient conversion of plant biomass to biofuels is the recalcitrant nature of the plant cell wall, which is composed mostly of lignocellulosic materials (lignin, cellulose, and hemicellulose). The heteropolymer xylan represents the most abundant hemicellulosic polysaccharide and is composed primarily of xylose, arabinose, and glucuronic acid. Microbes have evolved a plethora of enzymatic strategies for hydrolyzing xylan into its constituent sugars for subsequent fermentation to biofuels. Therefore, microorganisms are considered an important source of biocatalysts in the emerging biofuel industry. To produce an optimized enzymatic cocktail for xylan deconstruction, it will be valuable to gain insight at the molecular level of the chemical linkages and the mechanisms by which these enzymes recognize their substrates and catalyze their reactions. Recent advances in genomics, proteomics, and structural biology have revolutionized our understanding of the microbial xylanolytic enzymes. This review focuses on current understanding of the molecular basis for substrate specificity and catalysis by enzymes involved in xylan deconstruction. PMID:20431716

  6. Palm Date Fibers: Analysis and Enzymatic Hydrolysis

    Directory of Open Access Journals (Sweden)

    Mohammad J. Taherzadeh

    2010-11-01

    Full Text Available Waste palm dates were subjected to analysis for composition and enzymatic hydrolysis of their flesh fibers. The fruit contained 32% glucose and 30% fructose, while the water-insoluble fibers of its flesh consisted of 49.9% lignin and 20.9% polysaccharides. Water-insoluble fibers were settled to 55% of its initial volume in 12 h. The presence of skin and flesh colloidal fibers results in high viscosity and clogging problems during industrial processes. The settling velocity of the fibers was improved by enzymatic hydrolysis. Hydrolysis resulted in 84.3% conversion of the cellulosic part of the fibers as well as reducing the settling time to 10 minutes and the final settled volume to 4% of the initial volume. It implies easier separation of the fibers and facilitates fermentation processes in the corresponding industries. Two kinds of high- and low-lignin fibers were identified from the water-insoluble fibers. The high-lignin fibers (75% lignin settled easily, while the low-lignin fibers (41.4% lignin formed a slurry suspension which settled very slowly. The hydrophilicity of these low-lignin fibers is the major challenge of the industrial processes.

  7. Enzymatic processing of municipal solid waste.

    Science.gov (United States)

    Jensen, Jacob Wagner; Felby, Claus; Jørgensen, Henning; Rønsch, Georg Ørnskov; Nørholm, Nanna Dreyer

    2010-12-01

    The focus of this work was to investigate an enzymatic liquefaction of MSW organics, paper and cardboard. Liquefaction trials were conducted in different trial volumes: 50 g lab-scale trials and 5 0kg vessel-tests and evaluated based on particle size and viscosity. The viscosity results showed that Celluclast 1.5L had the singular significant effect on liquefaction of model MSW. No effect of α-amylase, protease and interaction in between and with cellulases on viscosity and particle size distribution was found in this study. Degradable material with a particle size above 1mm after treatment was evaluated using SEM microscopy. These results showed that paper particles were the main obstacles needing additional treatment in order to become fully liquefied. In a pilot scale test treating authentic MSW; more than 90% of initial organic and paper dry matter (DM) was recovered as liquid slurry after sieving through a 5-mm sieve. These tests were performed at up to 35% DM, showing that this process can easily manage high DM loadings. MSW enzymatic liquefaction promotes the separation of organics and paper from solids, which facilitate the use of these degradable fractions, with minimal loss, capable to enter a biogas plant through existing pipes. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Enzymatically crosslinked silk-hyaluronic acid hydrogels.

    Science.gov (United States)

    Raia, Nicole R; Partlow, Benjamin P; McGill, Meghan; Kimmerling, Erica Palma; Ghezzi, Chiara E; Kaplan, David L

    2017-07-01

    In this study, silk fibroin and hyaluronic acid (HA) were enzymatically crosslinked to form biocompatible composite hydrogels with tunable mechanical properties similar to that of native tissues. The formation of di-tyrosine crosslinks between silk fibroin proteins via horseradish peroxidase has resulted in a highly elastic hydrogel but exhibits time-dependent stiffening related to silk self-assembly and crystallization. Utilizing the same method of crosslinking, tyramine-substituted HA forms hydrophilic and bioactive hydrogels that tend to have limited mechanics and degrade rapidly. To address the limitations of these singular component scaffolds, HA was covalently crosslinked with silk, forming a composite hydrogel that exhibited both mechanical integrity and hydrophilicity. The composite hydrogels were assessed using unconfined compression and infrared spectroscopy to reveal of the physical properties over time in relation to polymer concentration. In addition, the hydrogels were characterized by enzymatic degradation and for cytotoxicity. Results showed that increasing HA concentration, decreased gelation time, increased degradation rate, and reduced changes that were observed over time in mechanics, water retention, and crystallization. These hydrogel composites provide a biologically relevant system with controllable temporal stiffening and elasticity, thus offering enhanced tunable scaffolds for short or long term applications in tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Fluorometric enzymatic assay of L-arginine

    Science.gov (United States)

    Stasyuk, Nataliya; Gayda, Galina; Yepremyan, Hasmik; Stepien, Agnieszka; Gonchar, Mykhailo

    2017-01-01

    The enzymes of L-arginine (further - Arg) metabolism are promising tools for elaboration of selective methods for quantitative Arg analysis. In our study we propose an enzymatic method for Arg assay based on fluorometric monitoring of ammonia, a final product of Arg splitting by human liver arginase I (further - arginase), isolated from the recombinant yeast strain, and commercial urease. The selective analysis of ammonia (at 415 nm under excitation at 360 nm) is based on reaction with o-phthalaldehyde (OPA) in the presence of sulfite in alkali medium: these conditions permit to avoid the reaction of OPA with any amino acid. A linearity range of the fluorometric arginase-urease-OPA method is from 100 nM to 6 μМ with a limit of detection of 34 nM Arg. The method was used for the quantitative determination of Arg in the pooled sample of blood serum. The obtained results proved to be in a good correlation with the reference enzymatic method and literature data. The proposed arginase-urease-OPA method being sensitive, economical, selective and suitable for both routine and micro-volume formats, can be used in clinical diagnostics for the simultaneous determination of Arg as well as urea and ammonia in serum samples.

  10. Comparison of the role that entropy has played in processes of non-enzymatic and enzymatic catalysis

    International Nuclear Information System (INIS)

    Dixon Pineda, Manuel Tomas

    2012-01-01

    The function that entropy has played is compared in processes of non-enzymatic and enzymatic catalysis. The processes followed are showed: the kinetics of the acid hydrolysis of 3-pentyl acetate and cyclopentyl acetate catalyzed by hydrochloric acid and enzymatic hydrolysis of ethyl acetate and γ-butyrolactone catalyzed by pig liver esterase. The activation parameters of Eyring were determined for each process and interpreted the contribution of the entropy of activation for catalysis in this type of model reactions. (author) [es

  11. Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse.

    Science.gov (United States)

    Agarwal, Vinayak; Miles, Zachary D; Winter, Jaclyn M; Eustáquio, Alessandra S; El Gamal, Abrahim A; Moore, Bradley S

    2017-04-26

    Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetic halogenation reactions range from simple aromatic substitutions to stereoselective C-H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removing halogen atoms from man-made organohalogens, yet also function naturally, albeit rarely, in metabolic pathways. This review details the scope and mechanism of nature's halogenation and dehalogenation enzymatic strategies, highlights gaps in our understanding, and posits where new advances in the field might arise in the near future.

  12. Inorganic Sulfur Oxidation by Aureobasidium pullulans

    OpenAIRE

    Killham, K.; Lindley, N. D.; Wainwright, M.

    1981-01-01

    Aureobasidium pullulans (de Bary) Arnaud isolated from the phylloplane of sycamore exposed to heavy atmospheric pollution oxidized S0 to S2O32−, S4O62−, and SO42− in vitro. The intermediates S2O32− and S4O62− were also oxidized to SO42−. Cell-free extracts of A. pullulans also oxidized reduced forms of S, the oxidation increasing linearly with increasing protein concentration, showing that the process is enzymatic. The possible role of fungi in S oxidation in soils is discussed.

  13. Inorganic Sulfur Oxidation by Aureobasidium pullulans

    Science.gov (United States)

    Killham, K.; Lindley, N. D.; Wainwright, M.

    1981-01-01

    Aureobasidium pullulans (de Bary) Arnaud isolated from the phylloplane of sycamore exposed to heavy atmospheric pollution oxidized S0 to S2O32−, S4O62−, and SO42− in vitro. The intermediates S2O32− and S4O62− were also oxidized to SO42−. Cell-free extracts of A. pullulans also oxidized reduced forms of S, the oxidation increasing linearly with increasing protein concentration, showing that the process is enzymatic. The possible role of fungi in S oxidation in soils is discussed. PMID:16345859

  14. Comparative study of the catalytic activity of [Mn(II)(bpy)2Cl2] and [Mn2(III/IV)(mu-O)2(bpy)4](ClO4)3 in the H2O2 induced oxidation of organic dyes in carbonate buffered aqueous solution.

    Science.gov (United States)

    Rothbart, Sabine; Ember, Erika; van Eldik, Rudi

    2010-04-07

    The kinetics of the hydrogen peroxide induced oxidative degradation of the azo dye Orange II in aqueous carbonate buffered solution were studied for the oxo-bridged [Mn(2)(III/IV)(mu-O)(2)(bpy)(4)](ClO(4))(3) complex and its mononuclear analogue [Mn(II)(bpy)(2)Cl(2)] as catalysts to reveal the underlying reaction mechanism and reactive intermediates participating in the catalytic cycle. Both catalysts show identical oxidative reactivity when used at equimolar manganese concentration. If a simple Mn(II) salt and a 1 : 2 concentration of bipyridine are added to the substrate and oxidant containing reaction mixture, the same oxidative reactivity as found for both readily prepared catalysts was observed for several investigated substrates. This demonstrates the in situ accessibility of a reactive intermediate and its precursor complex. The crucial role of bicarbonate as co-catalyst was studied. The distinct dependence of the observed rate constant for the oxidation reaction on the total carbonate concentration can be accounted for in terms of in situ generation of peroxycarbonate. EPR and rapid scan UV/Vis measurements of the reaction of hydrogen peroxide in carbonate buffered solution with [Mn(2)(III/IV)(mu-O)(2)(bpy)(4)](ClO(4))(3) and [Mn(II)(bpy)(2)Cl(2)], revealed for both catalysts the presence of monomeric Mn(II) and Mn(IV)-oxo species as the main intermediates. The proposed reaction mechanism involves two-electron oxidation of a mononuclear Mn(II) precursor complex to a high-valent Mn(IV)=O intermediate as catalytically active species. Differences in the activity of in situ prepared catalyst precursors of different metal to ligand ratios are reported. The 1 : 2 complex was found to be the catalytically more active precursor for the oxidation of the selected substrates, whereas the 1 : 3 complex rather catalyzed the disproportion of hydrogen peroxide.

  15. Nitrogen-doped graphene-silver nanodendrites for the non-enzymatic detection of hydrogen peroxide

    International Nuclear Information System (INIS)

    Tajabadi, M.T.; Basirun, W.J.; Lorestani, F.; Zakaria, R.; Baradaran, S.; Amin, Y.M.; Mahmoudian, M.R.; Rezayi, M.; Sookhakian, M.

    2015-01-01

    Highlights: • N-graphene/Ag nanodendrities by electrophoretic and electrochemical deposition. • Support of N-graphene shows efficient electrocatalytic activity toward H 2 O 2 reduction. • The fabricated non-enzymatic H 2 O 2 electrochemical sensor improved in the presence of Ag. - Abstract: An organic-metal hybrid film based on nitrogen-doped graphene-silver nanodendrites (Ag-NG) was fabricated on an indium tin oxide (ITO) electrode using a simple electrophoretic and electrochemical sequential deposition approach. The microwave-assisted method was utilized for the synthesis of nitrogen-doped graphene. This method involves a three-step process consisting of graphite oxidation, exfoliation, and finally chemical reduction with the use of hydrazine as the reducing agent, which leads to the simultaneous reduction of graphene oxide and production of nitrogen-doped graphene. The morphology and structure of the as-fabricated electrode were determined by X-ray diffraction, field emission electron microscopy and transmission electron microscopy. The as-prepared Ag-NG-modified ITO electrode exhibited superior electrocatalytic activity toward hydrogen peroxide (H 2 O 2 ) reduction, with a wide linear detection range of 100 μM to 80 mM (r = 0.9989) and a detection limit of 0.26 μM with a signal-to-noise ratio of 3. Furthermore, the fabricated non-enzymatic H 2 O 2 electrochemical sensor exhibited excellent stability and reproducibility

  16. Inhibition of cellulose enzymatic hydrolysis by laccase-derived compounds from phenols.

    Science.gov (United States)

    Oliva-Taravilla, Alfredo; Tomás-Pejó, Elia; Demuez, Marie; González-Fernández, Cristina; Ballesteros, Mercedes

    2015-01-01

    The presence of inhibitors compounds after pretreatment of lignocellulosic materials affects the saccharification and fermentation steps in bioethanol production processes. Even though, external addition of laccases selectively removes the phenolic compounds from lignocellulosic prehydrolysates, when it is coupled to saccharification step, lower hydrolysis yields are attained. Vanillin, syringaldehyde and ferulic acid are phenolic compounds commonly found in wheat-straw prehydrolysate after steam-explosion pretreatment. These three phenolic compounds were used in this study to elucidate the inhibitory mechanisms of laccase-derived compounds after laccase treatment. Reaction products derived from laccase oxidation of vanillin and syringaldehyde showed to be the strongest inhibitors. The presence of these products causes a decrement on enzymatic hydrolysis yield of a model cellulosic substrate (Sigmacell) of 46.6 and 32.6%, respectively at 24 h. Moreover, a decrease in more than 50% of cellulase and β-glucosidase activities was observed in presence of laccase and vanillin. This effect was attributed to coupling reactions between phenoxyl radicals and enzymes. On the other hand, when the hydrolysis of Sigmacell was performed in presence of prehydrolysate from steam-exploded wheat straw a significant inhibition on enzymatic hydrolysis was observed independently of laccase treatment. This result pointed out that the other components of wheat-straw prehydrolysate are affecting the enzymatic hydrolysis to a higher extent than the possible laccase-derived products. © 2015 American Institute of Chemical Engineers.

  17. Simultaneous sonochemical-enzymatic coating of medical textiles with antibacterial ZnO nanoparticles.

    Science.gov (United States)

    Petkova, Petya; Francesko, Antonio; Perelshtein, Ilana; Gedanken, Aharon; Tzanov, Tzanko

    2016-03-01

    The antimicrobial finishing is a must for production of medical textiles, aiming at reducing the bioburden in clinical wards and consequently decreasing the risk of hospital-acquired infections. This work reports for the first time on a simultaneous sonochemical/enzymatic process for durable antibacterial coating of cotton with zinc oxide nanoparticles (ZnO NPs). The novel technology goes beyond the "stepwise" concept we proposed recently for enzymatic pre-activation of the fabrics and subsequent sonochemical nano-coating, and is designed to produce "ready-to-use" antibacterial medical textiles in a single step. A multilayer coating of uniformly dispersed NPs was obtained in the process. The enzymatic treatment provides better adhesion of the ZnO NPs and, as a consequence, enhanced coating stability during exploitation. The NPs-coated cotton fabrics inhibited the growth of the medically relevant Staphylococcus aureus and Escherichia coli respectively by 67% and 100%. The antibacterial efficiency of these textile materials resisted the intensive laundry regimes used in hospitals, though only 33% of the initially deposited NPs remained firmly fixed onto the fabrics after multiple washings. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Process technology for multi-enzymatic reaction systems

    DEFF Research Database (Denmark)

    Xue, Rui; Woodley, John M.

    2012-01-01

    In recent years, biocatalysis has started to provide an important green tool in synthetic organic chemistry. Currently, the idea of using multi-enzymatic systems for industrial production of chemical compounds becomes increasingly attractive. Recent examples demonstrate the potential of enzymatic...

  19. Al(III, Cu(II, Co(II, Pb(II, Mn(II, and Fe(III DETERMINATIONS IN VARIOUS SAMPLES by FAAS AFTER SOLID PHASE EXTRACTION

    Directory of Open Access Journals (Sweden)

    Şule Dinç Zor

    2016-08-01

    Full Text Available In this study, a novel method for the preconcentration of of Al(III, Cu(II, Co(II, Pb(II, Mn(II, and Fe(III in the form of their hematoxylin chelates using a column filled with Amberlite XAD-16 resin was proposed. Metal chelates collected on the resin were eluted by 1 mol/L nitric acid in acetone and determined by flame atomic absorption spectrometry (FAAS. The influences of some analytical parameters including pH, flow rates, sample volume, the type and concentration of eluent on the preconcentration efficiency were examined. Effects of some interfering ions on the recovery values of analytes were also investigated. While optimum pH value was 8.5 for Cu(II, Co(II, Mn(II, and Fe(III ions, it was 6.5 for Al(III and Pb(II ions. Appropriate eluent for quantitative elution was 8 mL of 1 mol/L nitric acid in acetone. Sample and eluent flow rates were found to be 2 mL/min. The maximum sample volume was established by changing the sample volume from 50 mL to 2500 mL. The sample volume does not significantly affect recovery within the range of 50-2000 mL of the sample volume for the investigated metal ions. The preconcentration factor obtained was 400. Under optimized conditions, the detection limits found as concentration which is threefold of the standard deviation of the blank solution were 0.053, 0.080, 0.620, 1.310, 0.330 and 0.120 µg/L for Al(III, Cu(II, Co(II, Pb(II, Mn(II, and Fe(III ions, respectively and the adsorption capacities for these ions were 0.47 ± 0.02, 0.81 ± 0.01, 0.66 ± 0.01, 0.58 ± 0.01, 0.91 ± 0.01, and 0.73 ± 0.02 mg/g, respectively. By using the certified reference materials, the accuracy of the method was verified. The proposed method was successfully applied to cigarette, hair, and some vegetable species.

  20. Spectroscopic and thermal degradation behavior of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with thiopental sodium anesthesia drug

    Science.gov (United States)

    Refat, Moamen S.

    2013-04-01

    A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized with thiopental sodium anesthesia drug. The elemental analyses of the complexes are confined to stoichiometry of the formulas [M(TPL)3]ṡnH2O (M = Cr(III) or Fe(III); n = 6 or 5), [M(TPL)2(H2O)2]ṡnH2O (M = Mn(II), Co(II) or Ni(II); n = 0 or 4), and [M(TPL)2] (M = Cu(II) or Zn(II); n = 2 or 0) respectively, where TPL is thiopental chelating agent. Structures have been discussed and suggested upon elemental analyses, infrared, Raman, electronic, electron spin resonance, 1H NMR spectral data and magnetic studies. The X-ray powder diffraction (XRD) was performed of metal complexes. The XRD patterns indicate crystalline nature for the complexes. The measured low molar conductance values in dimethylsulfoxide indicate that the complexes are non-electrolyte nature. Spectroscopic discussion refer that coordination take place through three types: Cdbnd N (pyrimidine moiety) nitrogen and C2sbnd S (2-thiolate group) for Cr(III), Mn(II) and Fe(III), C6dbnd O (amido group) oxygen and C2sbnd S (2-thiolate group) for Co(II) and Ni(II), and Cu(II) and Zn(II) ions coordinated via Cdbnd N (pyrimidine moiety) nitrogen, C2dbnd S (2-thiolate group) and C6dbnd O (amido group) oxygen, respectively. The thermal behavior (TG/DTG/DTA) of the complexes was studied and kinetic parameters were determined by Horowitz-Metzger and Coats-Redfern methods. The thiopental and its complexes have been screened for their antimicrobial (G+ and G-) bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa) and fungi (Aspergillus flavus and Candida albicans) activities by minimum inhibitory concentration (MIC) method.

  1. Zn(II, Mn(II and Sr(II Behavior in a Natural Carbonate Reservoir System. Part I: Impact of Salinity, Initial pH and Initial Zn(II Concentration in Atmospheric Conditions

    Directory of Open Access Journals (Sweden)

    Auffray B.

    2016-07-01

    Full Text Available The sorption of inorganic elements on carbonate minerals is well known in strictly controlled conditions which limit the impact of other phenomena such as dissolution and/or precipitation. In this study, we evidence the behavior of Zn(II (initially in solution and two trace elements, Mn(II and Sr(II (released by carbonate dissolution in the context of a leakage from a CO2 storage site. The initial pH chosen are either equal to the pH of the water-CO2 equilibrium (~ 2.98 or equal to the pH of the water-CO2-calcite system (~ 4.8 in CO2 storage conditions. From this initial influx of liquid, saturated or not with respect to calcite, the batch experiments evolve freely to their equilibrium, as it would occur in a natural context after a perturbation. The batch experiments are carried out on two natural carbonates (from Lavoux and St-Emilion with PCO2 = 10−3.5 bar, with different initial conditions ([Zn(II]i from 10−4 to 10−6 M, either with pure water or 100 g/L NaCl brine. The equilibrium regarding calcite dissolution is confirmed in all experiments, while the zinc sorption evidenced does not always correspond to the two-step mechanism described in the literature. A preferential sorption of about 10% of the concentration is evidenced for Mn(II in aqueous experiments, while Sr(II is more sorbed in saline conditions. This study also shows that this preferential sorption, depending on the salinity, is independent of the natural carbonate considered. Then, the simulations carried out with PHREEQC show that experiments and simulations match well concerning the equilibrium of dissolution and the sole zinc sorption, with log KZn(II ~ 2 in pure water and close to 4 in high salinity conditions. When the simulations were possible, the log K values for Mn(II and Sr(II were much different from those in the literature obtained by sorption in controlled conditions. It is shown that a new conceptual model regarding multiple Trace Elements (TE sorption is

  2. Structure of the enzymatically synthesized fructan inulin

    Energy Technology Data Exchange (ETDEWEB)

    Heyer, A.G.; Schroeer, B. [Max-Planck-Institut fuer Molekulare Pflanzenphysiologie, Karl-Liebknecht-Str. 25, 14476 Golm (Germany); Radosta, S. [Fraunhofer-Institut fuer Angewandte Polymerforschung, Postfach 126, 14504 Teltow (Germany); Wolff, D.; Czapla, S.; Springer, J. [Technische Universitaet Berlin, FG Makromolekulare Chemie, Str. des 17. Juni 135, 10623 Berlin (Germany)

    1998-12-15

    Construction, purification and characterization of a fusion protein of maltose-binding protein of Escherichia coli and the fructosyltransferase of Streptococcus mutans is described. With the purified protein, in vitro synthesis of inulin was performed. The obtained polysaccharide was characterized by high-performance size-exclusion chromatography (HPSEC) and static light scattering (SLS) in dilute aqueous and dimethyl sulfoxide solution. For all samples very high molecular weights between 60x10{sup 6} and 90x10{sup 6} g/mol and a remarkable small polydispersity index of 1.1 have been determined. Small root-mean-square radii of gyration point to a compact conformation in dilute solution. No difference between native and enzymatically synthesized inulin was observed by X-ray powder diffraction and thermoanalysis of solid samples. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  3. Structure of the enzymatically synthesized fructan inulin

    International Nuclear Information System (INIS)

    Heyer, A.G.; Schroeer, B.; Radosta, S.; Wolff, D.; Czapla, S.; Springer, J.

    1998-01-01

    Construction, purification and characterization of a fusion protein of maltose-binding protein of Escherichia coli and the fructosyltransferase of Streptococcus mutans is described. With the purified protein, in vitro synthesis of inulin was performed. The obtained polysaccharide was characterized by high-performance size-exclusion chromatography (HPSEC) and static light scattering (SLS) in dilute aqueous and dimethyl sulfoxide solution. For all samples very high molecular weights between 60x10 6 and 90x10 6 g/mol and a remarkable small polydispersity index of 1.1 have been determined. Small root-mean-square radii of gyration point to a compact conformation in dilute solution. No difference between native and enzymatically synthesized inulin was observed by X-ray powder diffraction and thermoanalysis of solid samples. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  4. Isothermal calorimetry on enzymatic biodiesel production

    DEFF Research Database (Denmark)

    Fjerbæk, Lene

    2008-01-01

    information about effects taking place when using lipases immobilized on an inert carrier for transesterification of a triglyceride and an alcohol as for biodiesel production. The biodiesel is produced by rapeseed oil and methanol as well as ethanol and a commercial biocatalyst Novozym 435 from Novozymes......Calorimetric investigations are very useful for real-time monitoring of reaction rate and heat. Various chemical and physical effects can be revealed and observed closely such as adsorption, mixing, evaporation, stirring and chemical reactions during a calorimetric experiment. For enzymatic...... containing a Candida Antarctica B lipase immobilized on an acrylic resin. The reaction investigated is characterized by immiscible liquids (oil, methanol, glycerol and biodiesel) and enzymes imm. on an inert carrier during reaction, which allows several effects to take place that during normal reaction...

  5. Isothermal calorimetry on enzymatic biodiesel production

    DEFF Research Database (Denmark)

    Fjerbæk, Lene

    2008-01-01

    information about effects taking place when using lipases immobilized on an inert carrier for transesterification of a triglyceride and an alcohol as for biodiesel production. The biodiesel is produced by rapeseed oil and methanol as well as ethanol and a commercial biocatalyst Novozym 435 from Novozymes...... containing a Candida Antarctica B lipase immobilized on an acrylic resin. The reaction investigated is characterized by immiscible liquids (oil, methanol, glycerol and biodiesel) and enzymes imm. on an inert carrier during reaction, which allows several effects to take place that during normal reaction...... conditions can not be elucidated. These effects have been observed with isothermal calorimetry bringing forth new information about the reaction of enzymes catalyzing transesterification. Enzymatic biodiesel production has until now not been investigated with isothermal microcalorimetry, but the results...

  6. [Studies of enzymatic synthesis of biodiesel].

    Science.gov (United States)

    Deng, Li; Tan, Tian-Wei; Wang, Fang

    2003-01-01

    Biodiesel, an alternative diesel fuel, fatty acid alkyl ester, is made from renewable biological sources such as vegetable oils and animal fats. Two processes for biodiesel synthesis, enzymatic lipase catalytic esterification from fatty acid and transesterification from oils and fats, was investigated. The effects of various lipases, enzyme amount and purity, solvent, water absorbent, inhibition of short chains alcohol, specificity of substrate, molar ratio of substrate on esterification were studied in detail. The esterification degree with the optimal parameter and process can reach up to 92%. The purity of biodiesel obtained by separation and purification is up to 98%, and the half-life of the immobilized lipase for the esterification process can be up to 360hr, Moreover, the preliminary studies of the transesterification including the amount of methanol and mode of adding methanol into reaction system were made. The transesterification degree with adding methanol stepwise can reach 83%.

  7. Cascade enzymatic reactions for efficient carbon sequestration.

    Science.gov (United States)

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. ENZYMATIC HYDROLYSIS OF AGRICULTURAL LIGNOCELLULOSIC BIOMASS

    Directory of Open Access Journals (Sweden)

    T. VINTILA

    2009-05-01

    Full Text Available The yield, productivity and cost for the enzymatic hydrolysis of cellulose to glucose are crucial for the production of second generation ethanol. In the first study we have evaluated the activity of several commercial cellulolytic enzymes and a crude extract of a local strain of Trichoderma viride. The load used was 15 U of cellulase/gram cellulose and 90 U of cellobiase/gram cellulose. The hydrolysis was carried out at 50oC and pH 4,8 for 96 hours. The best cellulose hydrolysis yield of 58% was obtained with the cocktail formed of crude cellulases from T. viride CMIT3.5 combined with Novozyme 188. This cocktail was used in the second study, when alkaline-steam pretreated wheat straw and corn stover where hydrolyzed at pH 4,8 for 96 hours. The temperature was set at 50oC and 40oC. The hydrolysis at lower temperature was tested for a future experiment of simultaneous hydrolysis and fermentation. An enzymatic assay using glucose-6-phosphate dehydrogenase was used to determine exclusively glucose, instead of wide-range sugar DNS assay. Reporting to 100 grams of wet pretreated biomass, the following results were obtained: 14.4 g% glucose for corn stover at 50oC and 13,0 g% at 40oC; 13,1 g% glucose for wheat straw at 50oC and 10.3 g% at 40oC. Considering that wheat straw contain 36.6% glucose-based carbohydrates, the hydrolysis yields are between 39.3% and 28.1%. Further studies, concerning the optimal parameters for cellulase cocktail will be made.

  9. ENZYMATIC HYDROLYSIS OF AGRICULTURAL LIGNOCELLULOSIC BIOMASS

    Directory of Open Access Journals (Sweden)

    S. STRAVA

    2009-05-01

    Full Text Available The yield, productivity and cost for the enzymatic hydrolysis of cellulose to glucoseare crucial for the production of second generation ethanol. In the first study wehave evaluated the activity of several commercial cellulolytic enzymes and a crudeextract of a local strain of Trichoderma viride. The load used was 15 U ofcellulase/gram cellulose and 90 U of cellobiase/gram cellulose. The hydrolysis wascarried out at 50oC and pH 4,8 for 96 hours. The best cellulose hydrolysis yield of58% was obtained with the cocktail formed of crude cellulases from T. virideCMIT3.5 combined with Novozyme 188. This cocktail was used in the second study,when alkaline-steam pretreated wheat straw and corn stover where hydrolyzed at pH4,8 for 96 hours. The temperature was set at 50oC and 40oC. The hydrolysis at lowertemperature was tested for a future experiment of simultaneous hydrolysis andfermentation. An enzymatic assay using glucose-6-phosphate dehydrogenase wasused to determine exclusively glucose, instead of wide-range sugar DNS assay.Reporting to 100 grams of wet pretreated biomass, the following results wereobtained: 14.4 g% glucose for corn stover at 50oC and 13,0 g% at 40oC; 13,1 g%glucose for wheat straw at 50oC and 10.3 g% at 40oC. Considering that wheat strawcontain 36.6% glucose-based carbohydrates, the hydrolysis yields are between39.3% and 28.1%. Further studies, concerning the optimal parameters for cellulasecocktail will be made.

  10. XPS determination of Mn oxidation states in Mn (hydr)oxides

    International Nuclear Information System (INIS)

    Ilton, Eugene S.; Post, Jeffrey E.; Heaney, Peter J.; Ling, Florence T.; Kerisit, Sebastien N.

    2016-01-01

    Graphical abstract: - Highlights: • Systematic fitting the XPS Mn3p, Mn2p, and Mn3s to determine oxidation states of Mn (hydr)oxides. • Analysis of using the Mn3s multiplet splitting for determining valence of Mn(hydr)oxides. • Provided an easy to implement method for determining Mn oxidation states using XPS. - Abstract: Hydrous manganese oxides are an important class of minerals that help regulate the geochemical redox cycle in near-surface environments and are also considered to be promising catalysts for energy applications such as the oxidation of water. A complete characterization of these minerals is required to better understand their catalytic and redox activity. In this contribution an empirical methodology using X-ray photoelectron spectroscopy (XPS) is developed to quantify the oxidation state of hydrous multivalent manganese oxides with an emphasis on birnessite, a layered structure that occurs commonly in soils but is also the oxidized endmember in biomimetic water-oxidation catalysts. The Mn2p 3/2 , Mn3p, and Mn3s lines of near monovalent Mn(II), Mn(III), and Mn(IV) oxides were fit with component peaks; after the best fit was obtained the relative widths, heights and binding energies of the components were fixed. Unknown multivalent samples were fit such that binding energies, intensities, and peak-widths of each oxidation state, composed of a packet of correlated component peaks, were allowed to vary. Peak-widths were constrained to maintain the difference between the standards. Both average and individual mole fraction oxidation states for all three energy levels were strongly correlated, with close agreement between Mn3s and Mn3p analyses, whereas calculations based on the Mn2p 3/2 spectra gave systematically more reduced results. Limited stoichiometric analyses were consistent with Mn3p and Mn3s. Further, evidence indicates the shape of the Mn3p line was less sensitive to the bonding environment than that for Mn2p. Consequently, fitting the

  11. Enzymatic Hydrolysis of Hydrotropic Pulps at Different Substrate Loadings.

    Science.gov (United States)

    Denisova, Marina N; Makarova, Ekaterina I; Pavlov, Igor N; Budaeva, Vera V; Sakovich, Gennady V

    2016-03-01

    Enzymatic hydrolysis of cellulosic raw materials to produce nutrient broths for microbiological synthesis of ethanol and other valuable products is an important field of modern biotechnology. Biotechnological processing implies the selection of an effective pretreatment technique for raw materials. In this study, the hydrotropic treatment increased the reactivity of the obtained substrates toward enzymatic hydrolysis by 7.1 times for Miscanthus and by 7.3 times for oat hulls. The hydrotropic pulp from oat hulls was more reactive toward enzymatic hydrolysis compared to that from Miscanthus, despite that the substrates had similar compositions. As the initial substrate loadings were raised during enzymatic hydrolysis of the hydrotropic Miscanthus and oat hull pulps, the concentration of reducing sugars increased by 34 g/dm(3) and the yield of reducing sugars decreased by 31 %. The findings allow us to predict the efficiency of enzymatic hydrolysis of hydrotropic pulps from Miscanthus and oat hulls when scaling up the process by volume.

  12. Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

    Science.gov (United States)

    Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

    2018-06-15

    The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. A novel enzymatic system against oxidative stress in the thermophilic hydrogen-oxidizing bacterium Hydrogenobacter thermophilus.

    Directory of Open Access Journals (Sweden)

    Yuya Sato

    Full Text Available Rubrerythrin (Rbr is a non-heme iron protein composed of two distinctive domains and functions as a peroxidase in anaerobic organisms. A novel Rbr-like protein, ferriperoxin (Fpx, was identified in Hydrogenobacter thermophilus and was found not to possess the rubredoxin-like domain that is present in typical Rbrs. Although this protein is widely distributed among aerobic organisms, its function remains unknown. In this study, Fpx exhibited ferredoxin:NADPH oxidoreductase (FNR-dependent peroxidase activity and reduced both hydrogen peroxide (H(2O(2 and organic hydroperoxide in the presence of NADPH and FNR as electron donors. The calculated K(m and V(max values of Fpx for organic hydroperoxides were comparable to that for H(2O(2, demonstrating a multiple reactivity of Fpx towards hydroperoxides. An fpx gene disruptant was unable to grow under aerobic conditions, whereas its growth profiles were comparable to those of the wild-type strain under anaerobic and microaerobic conditions, clearly indicating the indispensability of Fpx as an antioxidant of H. thermophilus in aerobic environments. Structural analysis suggested that domain-swapping occurs in Fpx, and this domain-swapped structure is well conserved among thermophiles, implying the importance of structural stability of domain-swapped conformation for thermal environments. In addition, Fpx was located on a deep branch of the phylogenetic tree of Rbr and Rbr-like proteins. This finding, taken together with the wide distribution of Fpx among Bacteria and Archaea, suggests that Fpx is an ancestral type of Rbr homolog that functions as an essential antioxidant and may be part of an ancestral peroxide-detoxification system.

  14. Real-time monitoring of mass-transport-related enzymatic reaction kinetics in a nanochannel-array reactor.

    Science.gov (United States)

    Li, Su-Juan; Wang, Chen; Wu, Zeng-Qiang; Xu, Jing-Juan; Xia, Xing-Hua; Chen, Hong-Yuan

    2010-09-03

    To understand the fundamentals of enzymatic reactions confined in micro-/nanosystems, the construction of a small enzyme reactor coupled with an integrated real-time detection system for monitoring the kinetic information is a significant challenge. Nano-enzyme array reactors were fabricated by covalently linking enzymes to the inner channels of a porous anodic alumina (PAA) membrane. The mechanical stability of this nanodevice enables us to integrate an electrochemical detector for the real-time monitoring of the formation of the enzyme reaction product by sputtering a thin Pt film on one side of the PAA membrane. Because the enzymatic reaction is confined in a limited nanospace, the mass transport of the substrate would influence the reaction kinetics considerably. Therefore, the oxidation of glucose by dissolved oxygen catalyzed by immobilized glucose oxidase was used as a model to investigate the mass-transport-related enzymatic reaction kinetics in confined nanospaces. The activity and stability of the enzyme immobilized in the nanochannels was enhanced. In this nano-enzyme reactor, the enzymatic reaction was controlled by mass transport if the flux was low. With an increase in the flux (e.g., >50 microL min(-1)), the enzymatic reaction kinetics became the rate-determining step. This change resulted in the decrease in the conversion efficiency of the nano-enzyme reactor and the apparent Michaelis-Menten constant with an increase in substrate flux. This nanodevice integrated with an electrochemical detector could help to understand the fundamentals of enzymatic reactions confined in nanospaces and provide a platform for the design of highly efficient enzyme reactors. In addition, we believe that such nanodevices will find widespread applications in biosensing, drug screening, and biochemical synthesis.

  15. Binderless solution processed Zn doped Co3O4 film on FTO for rapid and selective non-enzymatic glucose detection

    CSIR Research Space (South Africa)

    Chowdhury, M

    2016-09-01

    Full Text Available A simple solution based deposition process has been used to fabricate Zn doped Co(sub3)O(sub4) electrode as an electrocatalyst for non-enzymatic oxidation of glucose. XRD, HRTEM, SEM, EELS, AFM, EIS was used to characterise the electrode...

  16. The properties and kinetics of enzymatic reaction in the process of the enzymatic extraction of fish oil.

    Science.gov (United States)

    Qian, Junqing; Zhang, Hongyong; Liao, Qiyuan

    2011-06-01

    The technology of enzymatic extraction of fish oil has many advantages, such as moderate operating conditions, lower energy consumption and high efficiency. Moreover, it could reduce the breakage for the functional component of fish oil. In enzymatic extraction of oil, the investigation of the property of enzymatic reaction is propitious to improve the enzymolysis efficiency. In this study, the 1398 neutrase was used for hydrolyzing fish protein, then analyzed the impacts to the enzymolysis efficiency which were induced by the different initial substrate concentration and different initial enzyme concentration, the result showed that the higher substrate concentration generate inhibition to the enzyme. And then, the properties of enzymatic hydrolysis were studied by the Michaelis-Menten equation of substrate inhibition and the enzymatic hydrolysis kinetics equation which is derived by theory. By means of the verification to the enzymatic hydrolysis kinetics model, it could see that the model in line with the actual situation better at a lower degree of hydrolysis. Lastly, the critical enzyme concentration and critical substrate concentration of enzymatic reaction could be obtained by deducing the enzymatic hydrolysis kinetics model.

  17. Enzymatic and non-enzymatic detoxification of 4-hydroxynonenal: Methodological aspects and biological consequences.

    Science.gov (United States)

    Mol, Marco; Regazzoni, Luca; Altomare, Alessandra; Degani, Genny; Carini, Marina; Vistoli, Giulio; Aldini, Giancarlo

    2017-10-01

    4-Hydroxynonenal (HNE), an electrophilic end-product deriving from lipid peroxidation, undergoes a heterogeneous set of biotransformations including enzymatic and non-enzymatic reactions. The former mostly involve red-ox reactions on the HNE oxygenated functions (phase I metabolism) and GSH conjugations (phase II) while the latter are due to the HNE capacity to spontaneously condense with nucleophilic sites within endogenous molecules such as proteins, nucleic acids and phospholipids. The overall metabolic fate of HNE has recently attracted great interest not only because it clearly determines the HNE disposal, but especially because the generated metabolites and adducts are not inactive molecules (as initially believed) but show biological activities even more pronounced than those of the parent compound as exemplified by potent pro-inflammatory stimulus induced by GSH conjugates. Similarly, several studies revealed that the non-enzymatic reactions, initially considered as damaging processes randomly involving all endogenous nucleophilic reactants, are in fact quite selective in terms of both reactivity of the nucleophilic sites and stability of the generated adducts. Even though many formed adducts retain the expected toxic consequences, some adducts exhibit well-defined beneficial roles as documented by the protective effects of sublethal concentrations of HNE against toxic concentrations of HNE. Clearly, future investigations are required to gain a more detailed understanding of the metabolic fate of HNE as well as to identify novel targets involved in the biological activity of the HNE metabolites. These studies are and will be permitted by the continuous progress in the analytical methods for the identification and quantitation of novel HNE metabolites as well as for proteomic analyses able to offer a comprehensive picture of the HNE-induced adducted targets. On these grounds, the present review will focus on the major enzymatic and non-enzymatic HNE

  18. Spectroscopic (FT-IR, FT-Raman, 1H, 13C NMR, UV/VIS), thermogravimetric and antimicrobial studies of Ca(II), Mn(II), Cu(II), Zn(II) and Cd(II) complexes of ferulic acid

    Science.gov (United States)

    Kalinowska, M.; Piekut, J.; Bruss, A.; Follet, C.; Sienkiewicz-Gromiuk, J.; Świsłocka, R.; Rzączyńska, Z.; Lewandowski, W.

    2014-03-01

    The molecular structure of Mn(II), Cu(II), Zn(II), Cd(II) and Ca(II) ferulates (4-hydroxy-3-methoxycinnamates) was studied. The selected metal ferulates were synthesized. Their composition was established by means of elementary and thermogravimetric analysis. The following spectroscopic methods were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (13C, 1H NMR) and ultraviolet-visible (UV/VIS). On the basis of obtained results the electronic charge distribution in studied metal complexes in comparison with ferulic acid molecule was discussed. The microbiological study of ferulic acid and ferulates toward Escherichia coli, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris was done.

  19. Syntheses, X-ray structures, solid state high-field electron paramagnetic resonance, and density-functional theory investigations on chloro and aqua Mn(II) mononuclear complexes with amino-pyridine pentadentate ligands.

    Science.gov (United States)

    Hureau, Christelle; Groni, Sihem; Guillot, Régis; Blondin, Geneviève; Duboc, Carole; Anxolabéhère-Mallart, Elodie

    2008-10-20

    The two pentadentate amino-pyridine ligands L5(2) and L5(3) (L5(2) and L5(3) stand for the N-methyl-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine and the N-methyl-N,N',N'-tris(2-pyridylmethyl)propane-1,3-diamine, respectively) were used to synthesize four mononuclear Mn(II) complexes, namely [(L5(2))MnCl](PF6) (1(PF6)), [(L5(3))MnCl](PF6) (2(PF6)), [(L5(2))Mn(OH2)](BPh4)2 (3(BPh4)2), and [(L5(3))Mn(OH2)](BPh4)2 (4(BPh4)2). The X-ray diffraction studies revealed different configurations for the ligand L5(n) (n = 2, 3) depending on the sixth exogenous ligand and/or the counterion. Solid state high-field electron paramagnetic resonance spectra were recorded on complexes 1-4 as on previously described mononuclear Mn(II) systems with tetra- or hexadentate amino-pyridine ligands. Positive and negative axial zero-field splitting (ZFS) parameters D were determined whose absolute values ranged from 0.090 to 0.180 cm(-1). Density-functional theory calculations were performed unraveling that, in contrast with chloro systems, the spin-spin and spin-orbit coupling contributions to the D-parameter are comparable for mixed N,O-coordination sphere complexes.

  20. Column solid phase extraction and flame atomic absorption spectrometric determination of manganese(II) and iron(III) ions in water, food and biological samples using 3-(1-methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid on synthesized graphene oxide.

    Science.gov (United States)

    Pourjavid, Mohammad Reza; Sehat, Ali Akbari; Arabieh, Masoud; Yousefi, Seyed Reza; Hosseini, Majid Haji; Rezaee, Mohammad

    2014-02-01

    A modified, selective, highly sensitive and accurate procedure for the determination of trace amounts of manganese and iron ions is established in the presented work. 3-(1-Methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid (MPPC) and graphene oxide (GO) were used in a glass column as chelating reagent and as adsorbent respectively prior to their determination by flame atomic absorption spectrometry. The adsorption mechanism of titled metals complexes on GO was investigated by using computational chemistry approach based on PM6 semi-empirical potential energy surface (PES). The effect of some parameters including pH, flow rate and volume of sample and type, volume and concentration of eluent, as well as the adsorption capacity of matrix ions on the recovery of Mn(II) and Fe(III) was investigated. The limit of detection was 145 and 162 ng L(-1) for Mn(II) and Fe(III), respectively. Calibration was linear over the range of 0.31-355 μg L(-1) for Mn(II) and 0.34-380 μg L(-1) for Fe(III) ions. The method was successfully applied for the determination of understudied ions in water, food and biological samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Non-Enzymatic Glucose Biosensor Based on CuO-Decorated CeO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Panpan Guan

    2016-08-01

    Full Text Available Copper oxide (CuO-decorated cerium oxide (CeO2 nanoparticles were synthesized and used to detect glucose non-enzymatically. The morphological characteristics and structure of the nanoparticles were characterized through transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The sensor responses of electrodes to glucose were investigated via an electrochemical method. The CuO/CeO2 nanocomposite exhibited a reasonably good sensitivity of 2.77 μA mM−1cm−2, an estimated detection limit of 10 μA, and a good anti-interference ability. The sensor was also fairly stable under ambient conditions.

  2. The effect of chemical, physical and enzymatic treatments on the dewatering of tar sands tailings

    Energy Technology Data Exchange (ETDEWEB)

    Theriault, Y.; Masliyah, J.H.; Fedorak, P.M.; Vazquez-Duhalt, R.; Gray, M.R. [University of Alberta, Edmonton, AB (Canada). Dept. of Chemical Engineering

    1995-09-01

    Fine tailings (with solids {lt} 106{mu}m) from hot-water extraction of the Athabasca tar sands were subjected to thermal, physical, chemical and enzymatic treatments in an attempt to modify the dewatering characteristics of the solid particles. A low-speed centrifuge at circa 1500 relative centrifugal force for 15 h was used to accelerate the sedimentation of the solids, and allowed comparison of the ultimate concentration of solids after the various treatments. Fine tailings were subjected to thermal treatment, sonication and modification of the water chemistry. Although the rate of sedimentation was affected by these treatments, the ultimate volume fraction of solids after centrifuging was about 0.3 (50-55 wt% solids). Extraction of the tailings to remove bitumen, humins and other organic components also failed to change the ultimate solids concentration. Oxidation of the organic material in the tailings by hydrogen peroxide in Fenton`s reagent, and enzymatic oxidation with lignin peroxidase, manganese peroxidase, cytochrome c, horseradish peroxidase and cowpea peroxidase gave no significant effect on the volume fraction of solids in the sediment after centrifugation. The observation that all of these treated samples gave an ultimate volume fraction of solids of about 0.3 indicated that bitumen, adsorbed organic matter and salts had little effect on the ultimate dewatering of tailings. 26 refs., 3 figs., 5 tabs.

  3. Production of prebiotic oligosaccharides by novel enzymatic catalysis

    DEFF Research Database (Denmark)

    Nordvang, Rune Thorbjørn; Jers, Carsten

    evidence backing them up. Since chemical synthesis of carbohydrates is extremely cumbersome, it is generally accepted that HMOs must be produced biochemically and enzymatic in vitro production is a popular strategy. Thus, the purpose of this PhD project was to encompass as many of the aspects...... of the enzymatic production of HMOs as possible, and identify opportunities to improve the enzymes, reaction efficiencies and processes involved. For enzymatic in vitro production of HMOs, industrial side stream products are often used as substrates to reduce the final product price. However, to use...

  4. Phenols and lignin: Key players in reducing enzymatic hydrolysis yields of steam-pretreated biomass in presence of laccase.

    Science.gov (United States)

    Oliva-Taravilla, Alfredo; Tomás-Pejó, Elia; Demuez, Marie; González-Fernández, Cristina; Ballesteros, Mercedes

    2016-01-20

    Phenols are known as inhibitors for cellulases and fermentative microorganisms in bioethanol production processes. The addition of laccases removes the phenolic compounds and subsequently reduces the lag phase of the fermentative microorganism. However, the application of laccases diminishes glucose release during the enzymatic hydrolysis. In this study a model cellulosic substrate (Sigmacell) together with lignin extract, whole steam-pretreated wheat straw (slurry) and its water insoluble solid fraction (WIS) were subjected to enzymatic hydrolysis to evaluate the effects of laccase treatment in presence of lignin and phenols. The presence of laccase in enzymatic hydrolysis of Sigmacell with lignin extract reduced glucose yield by 37% compared with assays without laccase. Furthermore, this reduction was even more marked in presence of phenols (55% reduction). Interestingly, when hydrolyzing WIS, the addition of phenols coupled with laccase treatment did not show a reduction when compared with only laccase addition. This fact suggests the key role of lignin in the hydrolysis inhibition since in WIS the ratio cellulase per gram of lignin was much lower than in Sigmacell experiments. Finally, the lower cellobiose and xylose recoveries point out that phenolic oligomers formed by laccase oxidation play important roles in the inhibition of endoglucanases, cellobiohydrolases and xylanases. To conclude, the proportion of lignin and the composition of phenols are key players in the inhibition of cellulases when the enzymatic hydrolysis is combined with laccases detoxification. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Non-enzymatic U(VI) interactions with biogenic mackinawite

    Science.gov (United States)

    Veeramani, H.; Qafoku, N. P.; Kukkadapu, R. K.; Murayama, M.; Hochella, M. F.

    2011-12-01

    Reductive immobilization of hexavalent uranium [U(VI)] by stimulation of dissimilatory metal and/or sulfate reducing bacteria (DMRB or DSRB) has been extensively researched as a remediation strategy for subsurface U(VI) contamination. These bacteria derive energy by reducing oxidized metals as terminal electron acceptors, often utilizing organic substrates as electron donors. Thus, when evaluating the potential for in-situ uranium remediation in heterogeneous subsurface media, it is important to understand how the presence of alternative electron acceptors such as Fe(III) and sulfate affect U(VI) remediation and the long term behavior and reactivity of reduced uranium. Iron, an abundant subsurface element, represents a substantial sink for electrons from DMRB, and the reduction of Fe(III) leads to the formation of dissolved Fe(II) or to reactive biogenic Fe(II)- and mixed Fe(II)/Fe(III)- mineral phases. Consequently, abiotic U(VI) reduction by reactive forms of biogenic Fe(II) minerals could be a potentially important process for uranium immobilization. In our study, the DMRB Shewanella putrefaciens CN32 was used to synthesize a biogenic Fe(II)-bearing sulfide mineral: mackinawite, that has been characterized by XRD, SEM, HRTEM and Mössbauer spectroscopy. Batch experiments involving treated biogenic mackinawite and uranium (50:1 molar ratio) were carried out at room temperature under strict anoxic conditions. Following complete removal of uranium from solution, the biogenic mackinawite was analyzed by a suite of analytical techniques including XAS, HRTEM and Mössbauer spectroscopy to determine the speciation of uranium and investigate concomitant Fe(II)-phase transformation. Determining the speciation of uranium is critical to success of a remediation strategy. The present work elucidates non-enzymatic/abiotic molecular scale redox interactions between biogenic mackinawite and uranium.

  6. Inorganic sulfur oxidation by Aureobasidium pullulans

    Energy Technology Data Exchange (ETDEWEB)

    Killham, K.; Lindley, N.D.; Wainwright, M.

    1981-10-01

    Aureobasidium pullulans (de Bary) Arnaud isolated from the phylloplane of sycamore exposed to heavy atmospheric pollution oxidized S/sup 0/ to S/sub 2/O/sub 3//sup 2 -/, S/sub 4/O/sub 6//sup 2 -/, and SO/sub 4//sup 2 -/. Cell-free extracts of A. pullulans also oxidized reduced forms of S, the oxidation increasing linearly with increasing protein concentration, showing that the process is enzymatic. The possible role of fungi in S oxidation in soils is discussed.

  7. Aqueous enzymatic extraction of Moringa oleifera oil.

    Science.gov (United States)

    Mat Yusoff, Masni; Gordon, Michael H; Ezeh, Onyinye; Niranjan, Keshavan

    2016-11-15

    This paper reports on the extraction of Moringa oleifera (MO) oil by using aqueous enzymatic extraction (AEE) method. The effect of different process parameters on the oil recovery was discovered by using statistical optimization, besides the effect of selected parameters on the formation of its oil-in-water cream emulsions. Within the pre-determined ranges, the use of pH 4.5, moisture/kernel ratio of 8:1 (w/w), and 300stroke/min shaking speed at 40°C for 1h incubation time resulted in highest oil recovery of approximately 70% (goil/g solvent-extracted oil). These optimized parameters also result in a very thin emulsion layer, indicating minute amount of emulsion formed. Zero oil recovery with thick emulsion were observed when the used aqueous phase was re-utilized for another AEE process. The findings suggest that the critical selection of AEE parameters is key to high oil recovery with minimum emulsion formation thereby lowering the load on the de-emulsification step. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Enzymatic hydrolysis of spent coffee ground.

    Science.gov (United States)

    Jooste, T; García-Aparicio, M P; Brienzo, M; van Zyl, W H; Görgens, J F

    2013-04-01

    Spent coffee ground (SCG) is the main residue generated during the production of instant coffee by thermal water extraction from roasted coffee beans. This waste is composed mainly of polysaccharides such as cellulose and galactomannans that are not solubilised during the extraction process, thus remaining as unextractable, insoluble solids. In this context, the application of an enzyme cocktail (mannanase, endoglucanase, exoglucanase, xylanase and pectinase) with more than one component that acts synergistically with each other is regarded as a promising strategy to solubilise/hydrolyse remaining solids, either to increase the soluble solids yield of instant coffee or for use as raw material in the production of bioethanol and food additives (mannitol). Wild fungi were isolated from both SCG and coffee beans and screened for enzyme production. The enzymes produced from the selected wild fungi and recombinant fungi were then evaluated for enzymatic hydrolysis of SCG, in comparison to commercial enzyme preparations. Out of the enzymes evaluated on SCG, the application of mannanase enzymes gave better yields than when only cellulase or xylanase was utilised for hydrolysis. The recombinant mannanase (Man1) provided the highest increments in soluble solids yield (17 %), even when compared with commercial preparations at the same protein concentration (0.5 mg/g SCG). The combination of Man1 with other enzyme activities revealed an additive effect on the hydrolysis yield, but not synergistic interaction, suggesting that the highest soluble solid yields was mainly due to the hydrolysis action of mannanase.

  9. Glucuronic Acid Derivatives in Enzymatic Biomass Degradation: Synthesis and Evaluation of Enzymatic Activity

    DEFF Research Database (Denmark)

    d'Errico, Clotilde

    -carbohydrate complexes found in lignocellulosic biomass, as model substrates for glucuronoyl esterases (GEs). These esters have been used to characterize a novel GE from Cerrena unicolor (CuGE), produced by Novozymes, to obtain insights into the substrate specificity of the enzymes. HPLC analysis of the enzymatic......An essential tool for biotechnology companies in enzyme development for biomass delignification is the access to well-defined model substrates. A deeper understanding of the enzymes substrate specificity can be used to address and optimize enzyme mixtures towards natural, complex substrates. Hence...

  10. Oxidative Reactions with Nonaqueous Enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Jonathan S. Dordick; Douglas Clark; Brian H Davison; Alexander Klibanov

    2001-12-30

    The objective of this work is to demonstrate a proof-of-concept of enzymatic oxidative processing in nonaqueous media using alkene epoxidation and phenolic polymerization as relevant targets. This project will provide both the fundamental and applied investigations necessary to initiate the implementation of oxidative biocatalysts as commercially relevant alternatives to chemical processing in general, and to phenolic polymerizations and alkene epoxidation specifically. Thus, this work will address the Bioprocessing Solicitation Area to: (1) makes major improvements to phenolic polymerization and alkene epoxidation technologies; (2) is expected to be cost competitive with competing conventional processes; and (3) produces higher yields with less waste.

  11. Modelling of the enzymatic kinetically controlled synthesis of cephalexin

    NARCIS (Netherlands)

    Schroën, C.G.P.H.; Fretz, C.B.; Bruin, de V.H.; Berendsen, W.; Moody, H.M.; Roos, E.C.; Roon, van J.L.; Kroon, P.J.; Strubel, M.; Janssen, A.E.M.; Tramper, J.

    2002-01-01

    In this study the influence of diffusion limitation on enzymatic kinetically controlled cephalexin synthesis from phenylglycine amide and 7-aminodeacetoxycephalosporinic acid (7-ADCA) was investigated systematically. It was found that if diffusion limitation occurred, both the synthesis/hydrolysis

  12. Anti-inflammatory activities of enzymatic (alcalase) hydrolysate of a ...

    African Journals Online (AJOL)

    Anti-inflammatory activities of enzymatic (alcalase) hydrolysate of a whey protein concentrate. LB de Carvalho-Silva, MTB Pacheco, R Bertoldo, C de Carvalho Veloso, LC Teodoro, A Giusti-Paiva, PCB Lollo, R Soncini ...

  13. Phyto-agglutinin, total proteins and amino assimilating enzymatic ...

    African Journals Online (AJOL)

    Jane

    2011-09-28

    2K cultivars extract showed highly phyto-agglutination of human erythrocytes with reproductive organs and other tissues, which represents the presence of potent lectins (phyto-agglutinin). The amino assimilating enzymatic.

  14. Recent insights in enzymatic synthesis of fructooligosaccharides from inulin.

    Science.gov (United States)

    Singh, Ram Sarup; Singh, Rupinder Pal; Kennedy, John F

    2016-04-01

    In the past few years, people are paying more attention to their dietary habits, and functional foods are playing a key role in maintaining the health of man. Prebiotics are considered as a main component of the functional foods which are usually composed of short chains of carbohydrates. Fructooligosaccharides (FOSs) are considered as one of the main group of prebiotics which have recognisable bifidogenic properties. FOSs are obtained either by extraction from various plant materials or by enzymatic synthesis from different substrates. Enzymatically, these can be obtained either from sucrose using fructosyltransferase or from inulin by endoinulinase. Inulin is a potent substrate for the enzymatic production of FOSs. This review article will provide an overview on the inulin as potent substrate, microbial sources of endoinulinases, enzymatic synthesis of FOSs from inulin, commercial status of FOSs, and their future perspectives. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Biosensing strategies based on enzymatic reactions and nanoparticles.

    Science.gov (United States)

    Díez-Buitrago, Beatriz; Briz, Nerea; Liz-Marzán, Luis M; Pavlov, Valeri

    2018-03-19

    Enzymes are pivotal elements in bioanalysis due to their specificity and extremely high catalytic activity. The sensitivity of bioanalytical assays depends mainly on the capacity of an observer to detect the product(s) of a biocatalytic reaction. Both natural and artificial compounds have been traditionally used to evaluate enzymatic activities. The drawbacks of chromogenic and fluorogenic organic enzymatic substrates are their high cost and low stability, resulting in high background signals. We review here state of the art assays in the detection of enzymatic activities using recent advances in nanoscience. Novel methods based on the use of nanoparticles lead to increased sensitivity and decreased costs for bioanalysis based on enzymes as recognition elements and signal amplifiers in Enzyme-Linked Immunosorbent Assays (ELISA). Novel approaches toward the detection of enzymatic activities are based on biocatalytic synthesis, modulation, etching, and aggregation of nanoparticles under physiological conditions.

  16. Intracellular trapping of cycloSal-pronucleotides by enzymatic cleavage.

    Science.gov (United States)

    Jessen, H J; Tonn, V; Meier, C

    2007-01-01

    A new synthesis for cycloSal-pronucleotides bearing enzymatically cleavable triggers is presented. This trigger is introduced to trap the pronucleotide inside cells. The general concept and hydrolysis data in different media are discussed.

  17. The effect of delignification of forest biomass on enzymatic hydrolysis.

    Science.gov (United States)

    Yu, Zhiying; Jameel, Hasan; Chang, Hou-Min; Park, Sunkyu

    2011-10-01

    The effect of delignification methods on enzymatic hydrolysis of forest biomass was investigated using softwood and hardwood that were pretreated at an alkaline condition followed by sodium chlorite or ozone delignification. Both delignifications improved enzymatic hydrolysis especially for softwood, while pretreatment alone was found effective for hardwood. High enzymatic conversion was achieved by sodium chlorite delignification when the lignin content was reduced to 15%, which is corresponding to 0.30-0.35 g/g accessible pore volume, and further delignification showed a marginal effect. Sample crystallinity index increased with lignin removal, but it did not show a correlation with the overall carbohydrate conversion of enzymatic hydrolysis. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Papaya pulp for enzymatic wound debridement in burns

    OpenAIRE

    Rajshree C Jayarajan; Puthucode V Narayanan; Hirji S Adenwalla

    2016-01-01

    Context: Early surgical debridement in burns has its disadvantages like extensive blood loss and long anaesthesia time and risks. Enzymatic wound debridement as an alternative to surgical debridement has been assessed for its effectiveness, safety and patient compliance. Aims: To assess the effectiveness and safety of papaya pulp as an enzymatic wound debriding agent in burns. Setting and Design: The study was conducted including 50 patients with second degree and third degree burns, age rang...

  19. Tomato volatile components: enzymatic formation of trans-2-hexenal

    International Nuclear Information System (INIS)

    Sieso, Victor; Nicolas, Michel; Seck, Souleymane; Crouzet, Jean

    1976-01-01

    Evidence of the presence of trans-2-hexenol among tomato volatile components was shown using heavy solvent extraction and absorption-desorption techniques. The action of alcohol deshydrogenase isolated from tomato fruit on trans-2-hexenal shows that the pathway for the formation of trans-2-hexenol is enzymatic. The presence of hexanal and hexanol besides this alcohol indicate that the reduction of the double bonds by the enzymatic preparation is also possible. (Kako, I.)

  20. The Aerobic Oxidation of Bromide to Dibromine Catalyzed by Homogeneous Oxidation Catalysts and Initiated by Nitrate in Acetic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Partenheimer, Walt; Fulton, John L.; Sorensen, Christina M.; Pham, Van Thai; Chen, Yongsheng

    2014-06-01

    A small amount of nitrate, ~0.002 molal, initiates the Co/Mn catalyzed aerobic oxidation of bromide compounds (HBr,NaBr,LiBr) to dibromine in acetic acid at room temperature. At temperatures 40oC or less , the reaction is autocatalytic. Co(II) and Mn(II) themselves and mixed with ionic bromide are known homogeneous oxidation catalysts. The reaction was discovered serendipitously when a Co/Br and Co/Mn/Br catalyst solution was prepared for the aerobic oxidation of methyaromatic compounds and the Co acetate contained a small amount of impurity i.e. nitrate. The reaction was characterized by IR, UV-VIS, MALDI and EXAFS spectroscopies and the coordination chemistry is described. The reaction is inhibited by water and its rate changed by pH. The change in these variables, as well as others, are identical to those observed during homogeneous, aerobic oxidation of akylaromatics. A mechanism is proposed. Accidental addition of a small amount of nitrate compound into a Co/Mn/Br/acetic acid mixture in a large, commercial feedtank is potentially dangerous.

  1. Kinetics of enzymatic hydrolysis of methyl ricinoleate

    Directory of Open Access Journals (Sweden)

    Neeharika, T. S.V.R.

    2015-12-01

    Full Text Available Ricinoleic acid is an unsaturated hydroxy fatty acid that naturally occurs in castor oil in proportions of up to 85–90%. Ricinoleic acid is a potential raw material and finds several applications in coatings, lubricant formulations and pharmaceutical areas. Enzymatic hydrolysis of castor oil is preferred over conventional hydrolysis for the preparation of ricinoleic acid to avoid estolide formation. A kinetics analysis of the enzymatic hydrolysis of Methyl Ricinoleate in the presence of Candida antarctica Lipase B was carried out in this study by varying reaction temperature (40–60 °C and enzyme concentration (2–5%. The optimal conditions were found to be 6 h reaction time, temperature 60°C, buffer to methyl ricinoleate ratio 2:1(v/w and 4% enzyme concentration to achieve a maximum conversion of 98.5%. A first order reversible reaction kinetic model was proposed to describe this reaction and a good agreement was observed between the experimental data and the model values. The effect of temperature on the forward reaction rate constant was determined by fitting data to the Arrhenius equation. The activation energy for forward reaction was found to be 14.69 KJ·mol−1.El ácido ricinoleico es un hidroxiácido insaturado que se produce naturalmente en el aceite de ricino en proporciones de hasta el 85–90%. El ácido ricinoleico es una materia prima con gran potencial y tiene aplicaciones en revestimientos, formulaciones lubricantes y en áreas farmacéuticas. Para la preparación del ácido ricinoleico se prefiere la hidrólisis enzimática del aceite de ricino a la hidrólisis convencional, para evitar la formación de estólidos. En este estudio se llevó a cabo la cinética de la hidrólisis enzimática del ricinoleato de metilo en presencia de lipasa de Candida antarctica B mediante la variación de la temperatura de reacción (40–60 °C y la concentración de la enzima (2–5%. Las condiciones óptimas de la reacción para

  2. The enzymatic and antioxidative stress response of Lemna minor to copper and a chloroacetamide herbicide.

    Science.gov (United States)

    Obermeier, Michael; Schröder, Christian A; Helmreich, Brigitte; Schröder, Peter

    2015-12-01

    Lemna minor L., a widely used model plant for toxicity tests has raised interest for its application to phytoremediation due to its rapid growth and ubiquitous occurrence. In rural areas, the pollution of water bodies with heavy metals and agrochemicals poses a problem to surface water quality. Among problematic compounds, heavy metals (copper) and pesticides are frequently found in water bodies. To establish duckweed as a potential plant for phytoremediation, enzymatic and antioxidative stress responses of Lemna minor during exposure to copper and a chloroacetamide herbicide were investigated in laboratory studies. The present study aimed at evaluating growth and the antioxidative and glutathione-dependent enzyme activity of Lemna plants and its performance in a scenario for phytoremediation of copper and a chloroacetamide herbicide. Lemna minor was grown in Steinberg medium under controlled conditions. Plants were treated with CuSO4 (ion conc. 50 and 100 μg/L) and pethoxamide (1.25 and 2.5 μg/L). Measurements following published methods focused on plant growth, oxidative stress, and basic detoxification enzymes. Duckweed proved to survive treatment with the respective concentrations of both pollutants very well. Its growth was inhibited scarcely, and no visible symptoms occurred. On the cellular basis, accumulation of O2(-) and H2O2 were detected, as well as stress reactions of antioxidative enzymes. Duckweed detoxification potential for organic pollutants was high and increased significantly with incubation. Pethoxamide was found to be conjugated with glutathione. Copper was accumulated in the fronds at high levels, and transient oxidative defense reactions were triggered. This work confirms the significance of L. minor for the removal of copper from water and the conjugation of the selective herbicide pethoxamide. Both organic and inorganic xenobiotics induced different trends of enzymatic and antioxidative stress response. The strong increase of stress

  3. Enhanced enzymatic conversion with freeze pretreatment of rice straw

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ken-Lin; Thitikorn-amorn, Jitladda; Ou, Bay-Ming; Chen, Shan-He; Huang, Po-Jung [Institute of Biological Chemistry and Genomics Research Center Academia Sinica, Nankang, Taipei 115 (China); Hsieh, Jung-Feng [Department of Food Science, Fu Jen Catholic University, Xin Zhuang, Taipei 242 (China); Ratanakhanokchai, Khanok [School of Bioresources and Technology, King Mongkut' s University of Technology Thonburi, Bangkok 10150 (Thailand); Chen, Shui-Tein [Institute of Biological Chemistry and Genomics Research Center Academia Sinica, Nankang, Taipei 115 (China); Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei 106 (China)

    2011-01-15

    Production of bioethanol by the conversion of lignocellulosic waste has attracted much interest in recent years, because of its low cost and great potential availability. The pretreatment process is important for increasing the enzymatic digestibility of lignocellulosic materials. Enzymatic conversion with freeze pretreatment of rice straw was evaluated in this study. The freeze pretreatment was found to significantly increase the enzyme digestibility of rice straw from 48% to 84%. According to the results, enzymatic hydrolysis of unpretreated rice straw with 150 U cellulase and 100 U xylanase for 48 h yielded 226.77 g kg{sup -1} and 93.84 g kg{sup -1} substrate-reducing sugars respectively. However, the reducing sugar yields from freeze pretreatment under the same conditions were 417.27 g kg{sup -1} and 138.77 g kg{sup -1} substrate, respectively. In addition, hydrolyzates analysis showed that the highest glucose yield obtained during the enzymatic hydrolysis step in the present study was 371.91 g kg{sup -1} of dry rice straw, following pretreatment. Therefore, the enhanced enzymatic conversion with freeze pretreatment of rice straw was observed in this study. This indicated that freeze pretreatment was highly effective for enzymatic hydrolysis and low environmental impact. (author)

  4. Oxidant activation of neutrophil collagenase

    International Nuclear Information System (INIS)

    Muthukumaran, G.; Amoruso, M.A.; Berg, R.A.

    1986-01-01

    Oxidant gas exposure leads to lung injury characterized by acute inflammation, connective tissue breakdown and alveolar damage. In an effort to better understand the mechanism for oxidant gas injury human peripheral neutrophils were isolated and incubated with 14 C-proline labelled extracellular matrix. Neutrophils in the presence of phorbol myristate acetate (PMA) alone (to stimulate the secretion of collagenase from specific granules) had no effect on the matrix. When neutrophils were incubated with PMA and 2 mM p-aminophenylmercuric acetate (APMA), the latter a known activator of collagenase, extensive degradation of the matrix was observed. The generation of the characteristic 3/4- and 1/4-clip fragments of Type I collagen was an indication that the major enzymatic activity operative was collagenase. This was further supported by its requirement for Ca 2+ and inhibition of enzymatic activity by EDTA. Further experiments indicated that 10 μM oxidized glutathione could replace APMA in activating the secreted collagenase. Since GSH is thought to be the major physiological antioxidant in the lung, the degradation of connective tissue caused by inflammation from oxidant gas injury may be attributed to the oxidation of GSH to GSSG with resultant activation of neutrophil collagenase

  5. Enzymatic sequencing of partially acetylated chitosan oligomers.

    Science.gov (United States)

    Hamer, Stefanie Nicole; Moerschbacher, Bruno Maria; Kolkenbrock, Stephan

    2014-06-17

    Chitosan oligosaccharides have diverse biological activities with potentially valuable applications, for example, in the fields of medicine and agriculture. These functionalities are thought to depend on their degree of polymerization and acetylation, and possibly on specific patterns of acetylation. Chitosan oligomers with fully defined architecture are difficult to produce, and their complete analysis is demanding. Analysis is typically done using MS or NMR, requiring access to expensive infrastructure, and yielding unequivocal results only in the case of rather small oligomers. We here describe a simple and cost-efficient method for the sequencing of μg amounts of chitosan oligosaccharides which is based on the sequential action of two recombinant glycosidases, namely an exo-β-N-acetylhexosaminidase (GlcNAcase) from Bacillus subtilis 168 and an exo-β-d-glucosaminidase (GlcNase) from Thermococcus kodakarensis KOD1. Starting from the non-reducing end, GlcNAcase and GlcNase specifically remove N-acetyl glucosamine (A) and glucosamine (D) units, respectively. By the sequential addition and removal of these enzymes in an alternating way followed by analysis of the products using high-performance thin-layer chromatography, the sequence of chitosan oligosaccharides can be revealed. Importantly, both enzymes work under identical conditions so that no buffer exchange is required between steps, and the enzyme can be removed conveniently using simple ultra-filtration devices. As proof-of-principle, the method was used to sequence the product of enzymatic deacetylation of chitin pentamer using a recombinant chitin deacetylase from Vibrio cholerae which specifically removes the acetyl group from the second unit next to the non-reducing end of the substrate, yielding mono-deacetylated pentamer with the sequence ADAAA. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Nanocrystal Bioassembly: Asymmetry, Proximity, and Enzymatic Manipulation

    Energy Technology Data Exchange (ETDEWEB)

    Claridge, Shelley A. [Univ. of California, Berkeley, CA (United States)

    2008-05-01

    Research at the interface between biomolecules and inorganic nanocrystals has resulted in a great number of new discoveries. In part this arises from the synergistic duality of the system: biomolecules may act as self-assembly agents for organizing inorganic nanocrystals into functional materials; alternatively, nanocrystals may act as microscopic or spectroscopic labels for elucidating the behavior of complex biomolecular systems. However, success in either of these functions relies heavily uponthe ability to control the conjugation and assembly processes.In the work presented here, we first design a branched DNA scaffold which allows hybridization of DNA-nanocrystal monoconjugates to form discrete assemblies. Importantly, the asymmetry of the branched scaffold allows the formation of asymmetric2assemblies of nanocrystals. In the context of a self-assembled device, this can be considered a step toward the ability to engineer functionally distinct inputs and outputs.Next we develop an anion-exchange high performance liquid chromatography purification method which allows large gold nanocrystals attached to single strands of very short DNA to be purified. When two such complementary conjugates are hybridized, the large nanocrystals are brought into close proximity, allowing their plasmon resonances to couple. Such plasmon-coupled constructs are of interest both as optical interconnects for nanoscale devices and as `plasmon ruler? biomolecular probes.We then present an enzymatic ligation strategy for creating multi-nanoparticle building blocks for self-assembly. In constructing a nanoscale device, such a strategy would allow pre-assembly and purification of components; these constructs can also act as multi-label probes of single-stranded DNA conformational dynamics. Finally we demonstrate a simple proof-of-concept of a nanoparticle analog of the polymerase chain reaction.

  7. CuO nanoparticles supported on nitrogen and sulfur co-doped graphene nanocomposites for non-enzymatic glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meixia [Hebei University of Engineering, Faculty of Material Science and Engineering (China); Guo, Qingbin, E-mail: guoqingbinhue@163.com [Hebei University of Engineering, Academic Affairs office (China); Xie, Juan; Li, Yongde; Feng, Yapeng [Hebei University of Engineering, Faculty of Material Science and Engineering (China)

    2017-01-15

    Developing highly active catalysts to promote the electrocatalytic glucose oxidation (EGO) is a crucial demand for non-enzymatic glucose sensing. Herein, we reported the use of nitrogen and sulfur co-doped graphene (NSG) as a novel support material for anchoring CuO nanoparticles and obtained CuO/NSG was employed as an efficient EGO catalyst for non-enzymatic glucose sensing. The results showed that the NSG endowed the CuO/NSG with large surface area, increased structural defects, improved conductivity, and strong covalent coupling between NSG and CuO. Owing to the significant contribution of NSG and the synergistic effect of NSG and CuO, the CuO/NSG exhibited a remarkably higher EGO activity than CuO and CuO/reduced graphene oxide. The CuO/NSG-based sensor displayed excellent glucose sensing performances with a considerably low detection limit of 0.07 μM. These findings elucidate that the NSG is a promising support material for non-enzymatic glucose detection.

  8. Enzymatic Hydrolysis and Ethanol Fermentation of High Dry Matter Wet-Exploded Wheat Straw at Low Enzyme Loading

    Science.gov (United States)

    Georgieva, Tania I.; Hou, Xiaoru; Hilstrøm, Troels; Ahring, Birgitte K.

    Wheat straw was pretreated by wet explosion using three different oxidizing agents (H2O2, O2, and air). The effect of the pretreatment was evaluated based on glucose and xylose liberated during enzymatic hydrolysis. The results showed that pretreatment with the use of O2 as oxidizing agent was the most efficient in enhancing overall convertibility of the raw material to sugars and minimizing generation of furfural as a by-product. For scale-up of the process, high dry matter (DM) concentrations of 15-20% will be necessary. However, high DM hydrolysis and fermentation are limited by high viscosity of the material, higher inhibition of the enzymes, and fermenting microorganism. The wet-explosion pretreatment method enabled relatively high yields from both enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) to be obtained when performed on unwashed slurry with 14% DM and a low enzyme loading of 10 FPU/g cellulose in an industrial acceptable time frame of 96 h. Cellulose and hemicellulose conversion from enzymatic hydrolysis were 70 and 68%, respectively, and an overall ethanol yield from SSF was 68%.

  9. Enzymatic Catalysis at Interfaces—Heterophase Systems as Substrates for Enzymatic Action

    Directory of Open Access Journals (Sweden)

    Katharina Landfester

    2013-04-01

    Full Text Available Several important enzymatic reactions occurring in nature, such as, e.g., the digestion of fat, proceed only at the interface of two immiscible phases. Typically, these systems consist of an organic substrate, dispersed in an aqueous continuous phase, with a specialized enzyme capable of working at the interface. For adopting such a system for organic synthesis, a stable heterophase system with a large interfacial area is required. These prerequisites can be found in so-called miniemulsions. Such liquid-liquid heterophase systems feature droplets with sizes smaller than 500 nm, and more importantly, these emulsions do not suffer from Ostwald ripening, as conventional emulsions do. Consequently, the droplets show long-term stability, even throughout reactions conducted in the droplets. In this review, we will briefly discuss the physicochemical background of miniemulsions, provide a comprehensive overview of the enzymatically catalyzed reactions conducted in miniemulsions and, as data are available, to compare the most important features to conventional systems, as reverse microemulsions, (macroemulsions and solvent-based systems.

  10. Enzymatic and non-enzymatic antioxidant potentials of Chlorella vulgaris grown in effluent of a confectionery industry

    OpenAIRE

    Kumar, R. Ranjith; Rao, P. Hanumantha; Subramanian, V. V.; Sivasubramanian, V.

    2011-01-01

    Enzymatic and non-enzymatic antioxidant potentials of Chlorella vulgaris have gained considerable importance in recent decades. C. vulgaris strain highly tolerant to extreme pH variations was isolated and mass-cultivated in the wastewater from a confectionery industry. C.vulgaris showed better growth in wastewater than in improvised CFTRI medium. The microalgal biomass was then screened for the following antioxidants: peroxidase, superoxide dismutase, polyphenol oxidase, glutathione peroxidas...

  11. ENZYMATIC CHANGES IN SNAKE ENVENOMATION- AN OBSERVATIONAL STUDY

    Directory of Open Access Journals (Sweden)

    Sidharth Kapoor

    2017-06-01

    levels were reduced to 3.27 mmol/L. CONCLUSION It was found that the mean rise in AST level was higher in neurotoxic cases than in haemotoxic cases on day 0, but on day 4, haemotoxic cases had still higher levels, but the value of AST had trend towards normalisation in neurotoxic cases. Since the mortality figures were too low to perform statistical analysis, the prognostic value of these changes could not be determined, hence, a larger study will be more informative. Since there is only one study available in literature in which effect of viperine venom enzymatic changes on male albino rats was studied, no definite conclusions could be drawn on the clinical studied, no definite conclusions could be drawn on the clinical implications of such changes in enzymatic assay after snake envenomation in human beings. Secondly, it is still not clear whether the oxidative stress after snake envenomation is because of effect on venom or is just on epiphenomenon, therefore, further work of similar nature is required before drawing definite conclusion.

  12. Enzymatic reduction of U(VI) in groundwaters; Reduction enzymatique de U(VI) dans des eaux souterraines

    Energy Technology Data Exchange (ETDEWEB)

    Addelouas, A.; Gong, W. [Center for Radioactive Waste Management, Advanced Materials Laboratory, 1001 University, Albuquerque (United States); Lutze, W.; Nuttall, E. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering; Fritz, B.; Crovisier, J.L. [Centre National de la Recherche Scientifique (CNRS), 67 - Strasbourg (France). Centre de Sedimentologie et Geochimie de la Surface

    1999-03-01

    The use of enzymatic reduction of U(VI) in remediation of groundwater contaminated with U(VI) is receiving considerable attention. Certain strains of bacteria can combine the oxidation of an organic compound to the reduction of U(VI) to U(IV), which precipitates as uraninite. In the present study, we tested the reduction of U(VI) in groundwaters with various origins and compositions. In all groundwaters u(VI) was reduced by sulfate reducing bacteria that had been activated by ethanol and tri-metaphosphate. The reduction rate of U(VI) depends on sulfate concentration in water and the abundance of bacteria in the system. This work shows that bacteria capable of U(VI) reduction are ubiquitous in nature, and suggests the possibility of a large application of the enzymatic reduction of U(VI) for in situ clean up of groundwaters contaminated with uranium. (authors) 12 refs.

  13. Redox polymer mediation for enzymatic biofuel cells

    Science.gov (United States)

    Gallaway, Joshua

    Mediated biocatalytic cathodes prepared from the oxygen-reducing enzyme laccase and redox-conducting osmium hydrogels were characterized for use as cathodes in enzymatic biofuel cells. A series of osmium-based redox polymers was synthesized with redox potentials spanning the range from 0.11 V to 0.85 V (SHE), and the resulting biocatalytic electrodes were modeled to determine reaction kinetic constants using the current response, measured osmium concentration, and measured apparent electron diffusion. As in solution-phase systems, the bimolecular rate constant for mediation was found to vary greatly with mediator potential---from 250 s-1M-1 when mediator and enzyme were close in potential to 9.4 x 10 4 s-1M-1 when this overpotential was large. Optimum mediator potential for a cell operating with a non-limiting platinum anode and having no mass transport limitation from bulk solution was found to be 0.66 V (SHE). Redox polymers were synthesized under different concentrations, producing osmium variation. An increase from 6.6% to 7.2% osmium increased current response from 1.2 to 2.1 mA/cm2 for a planar film in 40°C oxygen-saturated pH 4 buffer, rotating at 900 rpm. These results translated to high surface area electrodes, nearly doubling current density to 13 mA/cm2, the highest to date for such an electrode. The typical fungal laccase from Trametes versicolor was replaced by a bacterially-expressed small laccase from Streptomyces coelicolor, resulting in biocatalytic films that reduced oxygen at increased pH, with full functionality at pH 7, producing 1.5 mA/cm 2 in planar configuration. Current response was biphasic with pH, matching the activity profile of the free enzyme in solution. The mediated enzyme electrode system was modeled with respect to apparent electron diffusion, mediator concentration, and transport of oxygen from bulk solution, all of which are to some extent controlled by design. Each factor was found to limit performance in certain circumstances

  14. Oxidation Catalysis by Enzymes in Microemulsions

    Directory of Open Access Journals (Sweden)

    Evgenia Mitsou

    2017-02-01

    Full Text Available Microemulsions are regarded as “the ultimate enzyme microreactors” for liquid oxidations. Their structure, composed of water nanodroplets dispersed in a non-polar medium, provides several benefits for their use as media for enzymatic transformations. They have the ability to overcome the solubility limitations of hydrophobic substrates, enhance the enzymatic activity (superactivity phenomenon and stability, while providing an interface for surface-active enzymes. Of particular interest is the use of such systems to study biotransformations catalyzed by oxidative enzymes. Nanodispersed biocatalytic media are perfect hosts for liquid oxidation reactions catalyzed by many enzymes such as heme peroxidases, phenoloxidases, cholesterol oxidase, and dehydrogenases. The system’s composition and structural properties are important for better understanding of nanodispersion-biocatalyst interactions.

  15. Evolution of enzymatic activities and carbon fractions throughout composting of plant waste.

    Science.gov (United States)

    Jurado, M M; Suárez-Estrella, F; Vargas-García, M C; López, M J; López-González, J A; Moreno, J

    2014-01-15

    Many alternatives for the proper disposal of horticultural plant wastes have been studied, and composting is one of the most attractive due to its insignificant environmental impact and low cost. The quality of compost for agronomical use is related to the degree of organic matter maturation and stabilization. Traditional parameters as well as temperature, ratio C/N, cationic exchange capacity, extractable carbon, or evolution of humificated substances have been successfully used to assess compost maturity and stability. However, microorganisms frequently isolated during composting release a wide range of hydrolytic enzymes, whose activity could apparently give interesting information on the rate of decomposition of organic matter and, therefore, on the product stability. The aim of this work was to study the evolution of some important enzymatic activities during composting of agricultural wastes and their comparison with other chemical parameters commonly employed as quality and maturity indexes, to establish a relationship between the degradation intensity of specific organic carbon fractions throughout the process. In this work, the chemical and biochemical parameters of plant wastes were studied along a composting process of 189 days to evaluate their importance as tools for compost characterization. Results showed an intense enzymatic activity during the first 2-3 weeks of composting (bio-oxidative phase), because of the availability of easily decomposable organic compounds. From a biological point of view, a less intense phase was observed between second and third month of composting (mesophilic or cooling phase). Finally, chemical humification parameters were more closely associated with the period between 119 and 189 days (maturation phase). Significant correlations between the enzymatic activities as well as between enzyme activities and other more traditional parameters were also highlighted, indicating that both kind of indexes can be a reliable tool to

  16. Role of enzymatic and non enzymatic antioxidant in ameliorating salinity induced damage in nostoc muscorum

    International Nuclear Information System (INIS)

    Hend, A.; Abeer, A.; Allah, A.

    2015-01-01

    Presence of high salt concentration in the growth medium adversely affected the plant growth and productivity by altering its metabolic activities. Experiments were conducted on cyanobacteriaum Nostoc muscorum grown in nitrogen free medium supplemented with 250 mM NaCl to evaluate the salt stress induced changes in growth, antioxidants and lipid composition. Salt stress significantly reduced the growth and physio-biochemical attributes. Salt stress increased malonaldehyde content thereby causing alterations in the lipid fraction. Significant reduction in polyunsaturated fatty acids including phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylinositol (PI) and phosphatidylserine (PS) was observed. Where as diacylglycerol, sterol ester and non-esterified fatty acids were increased. Activities of antioxidant enzymes and contents of non-enzymatic antioxidants including glutathione enhanced due to salt stress. An increase in accumulation of proline was also observed. Hence increased activity of antioxidants and altered fatty acid composition was observed in salt stressed Nostoc muscorum. (author)

  17. Sulfate radicals enable a non-enzymatic Krebs cycle precursor.

    Science.gov (United States)

    Keller, Markus A; Kampjut, Domen; Harrison, Stuart A; Ralser, Markus

    2017-03-13

    The evolutionary origins of the tricarboxylic acid cycle (TCA), or Krebs cycle, are so far unclear. Despite a few years ago, the existence of a simple non-enzymatic Krebs-cycle catalyst has been dismissed 'as an appeal to magic', citrate and other intermediates have meanwhile been discovered on a carbonaceous meteorite and do interconvert non-enzymatically. To identify the non-enzymatic Krebs cycle catalyst, we used combinatorial, quantitative high-throughput metabolomics to systematically screen iron and sulfate reaction milieus that orient on Archean sediment constituents. TCA cycle intermediates are found stable in water and in the presence of most iron and sulfate species, including simple iron-sulfate minerals. However, we report that TCA intermediates undergo 24 interconversion reactions in the presence of sulfate radicals that form from peroxydisulfate. The non-enzymatic reactions critically cover a topology as present in the Krebs cycle, the glyoxylate shunt and the succinic semialdehyde pathways. Assembled in a chemical network, the reactions achieve more than ninety percent carbon recovery. Our results show that a non-enzymatic precursor for the Krebs cycle is biologically sensible, efficient, and forms spontaneously in the presence of sulfate radicals.

  18. A Highly Sensitive Electrochemical Glucose Sensor By Nickel-Epoxy Electrode With Non-Enzymatic Sensor

    Directory of Open Access Journals (Sweden)

    Riyanto Riyanto

    2016-03-01

    Full Text Available The preparation of new sensor for glucose was based on the fact that glucose can be determined by non-enzymatic glucose oxidase. The Ni metals (99.98% purity, 0.5 mm thick, Aldrich Chemical Company was used to prepare Ni-Epoxy electrode. The Ni-epoxy electrodes were prepared in square cut of 1 cm and 1 mm by length and wide respectively. The Ni metal electrodes were connected to silver wire with silver conducting paint prior covered with epoxy gum. The prepared of nickel-epoxy modified electrode showed outstanding electro catalytic activity toward the oxidation of glucose in alkaline solution. The result from this research are correlation of determination using Nickel-Epoxyelectrode for electroanalysis of glucose in NaOH was R2 = 0.9984. LOQ, LOD and recovery of the Nickel-Epoxy electrode towards glucose were found to be 4.4 μM, 1.48 μM and 98.19%, respectively. The Nickel-Epoxy wire based electrochemical glucose sensor demonstrates good sensitivity, wide linear range, outstanding detection limit, attractive selectivity, good reproducibility, high stability as well as prominent feasibility use of non-enzymatic sensor for monitoring glucose in human urine owing to its advantages of low cost, simple preparation and excellent properties for glucose detection.

  19. Two-Input Enzymatic Logic Gates Made Sigmoid by Modifications of the Biocatalytic Reaction Cascades

    Energy Technology Data Exchange (ETDEWEB)

    Zavalov, Oleksandr [Clarkson University, Potsdam, NY; Bocharova, Vera [ORNL; Halamek, Jan [Clarkson University, Potsdam, NY; Halamkova, Lenka [Clarkson University, Potsdam, NY; Korkmaz, Sevim [Clarkson University, Potsdam, NY; Arugula, Mary [University of Utah; Chinnapareddy, Soujanya [Clarkson University, Potsdam, NY; Katz, Evgeny [Clarkson University, Potsdam, NY; Privman, Vladimir [Clarkson University, Potsdam, NY

    2012-01-01

    Computing based on biochemical processes is a newest rapidly developing field of unconventional information and signal processing. In this paper we present results of our research in the field of biochemical computing and summarize the obtained numerical and experimental data for implementations of the standard two-input OR and AND gates with double-sigmoid shape of the output signal. This form of response was obtained as a function of the two inputs in each of the realized biochemical systems. The enzymatic gate processes in the first system were activated with two chemical inputs and resulted in optically detected chromogen oxidation, which happens when either one or both of the inputs are present. In this case, the biochemical system is functioning as the OR gate. We demonstrate that the addition of a filtering biocatalytic process leads to a considerable reduction of the noise transmission factor and the resulting gate response has sigmoid shape in both inputs. The second system was developed for functioning as an AND gate, where the output signal was activated only by a simultaneous action of two enzymatic biomarkers. This response can be used as an indicator of liver damage, but only if both of these of the inputs are present at their elevated, pathophysiological values of concentrations. A kinetic numerical model was developed and used to estimate the range of parameters for which the experimentally realized logic gate is close to optimal. We also analyzed the system to evaluate its noise-handling properties.

  20. Colorimetric method for enzymatic screening assay of ATP using Fe(III)-xylenol orange complex formation.

    Science.gov (United States)

    Ishida, Akihiko; Yamada, Yasuko; Kamidate, Tamio

    2008-11-01

    In hygiene management, recently there has been a significant need for screening methods for microbial contamination by visual observation or with commonly used colorimetric apparatus. The amount of adenosine triphosphate (ATP) can serve as the index of a microorganism. This paper describes the development of a colorimetric method for the assay of ATP, using enzymatic cycling and Fe(III)-xylenol orange (XO) complex formation. The color characteristics of the Fe(III)-XO complexes, which show a distinct color change from yellow to purple, assist the visual observation in screening work. In this method, a trace amount of ATP was converted to pyruvate, which was further amplified exponentially with coupled enzymatic reactions. Eventually, pyruvate was converted to the Fe(III)-XO complexes through pyruvate oxidase reaction and Fe(II) oxidation. As the assay result, yellow or purple color was observed: A yellow color indicates that the ATP concentration is lower than the criterion of the test, and a purple color indicates that the ATP concentration is higher than the criterion. The method was applied to the assay of ATP extracted from Escherichia coli cells added to cow milk.

  1. Changes in the secondary structure of proteins labeled with 125I. CD spectroscopy and enzymatic activity studies

    International Nuclear Information System (INIS)

    Efimova, Y.M.; Wierczinski, B.; Haemers, S.; Well, A.A. van

    2005-01-01

    Bovine serum albumin (BSA) and lysozyme (LSZ) were radiolabeled with 125 I. Three different methods for protein iodination with 125 I were optimized. Parameters like incubation time and ratio of oxidizing agent and amount of protein were established. During protein iodination with 125 I, structural damages caused by the introduction of iodine into the protein may occur. These damages depend on the oxidizing agent used and may lead to considerable changes in the protein structure and, hence, their biological activity. Changes in secondary structure of LSZ and BSA were examined by circular dichroism (CD). Enzymatic activity tests were performed with lysozyme to check its biological activity. The Iodo Bead was found the best oxidizing agent for protein iodination. (author)

  2. Perfluorinated quaternary ammonium salts of polyoxometalate anions: Fluorous biphasic oxidation catalysis with and without fluorous solvents

    Energy Technology Data Exchange (ETDEWEB)

    Maayan, Galia; Fish, Richard H.; Neumann, Ronny

    2003-05-28

    Perfluorinated quaternary ammonium cations, [CF{sub 3}(CF{sub 2}){sub 7}(CH{sub 2}){sub 3}]{sub 3}CH{sub 3}N{sup +} (RFN{sup +}), were synthesized and used as counter cations for the [WZnM{sub 2}(H{sub 2}O){sub 2}(ZnW{sub 9}O{sub 34}){sub 2}]{sup 12-} (M = Mn(II), Zn(II)), polyoxometalate. The (RFN{sup +}){sub 12}[WZnM{sub 2}(H{sub 2}O){sub 2}(ZnW9O{sub 34}){sub 2}] compounds were fluorous biphasic catalysts for alcohol and alkenol oxidation, and alkene epoxidation with aqueous hydrogen peroxide. Reaction protocols with or without a fluorous solvent were tested. The catalytic activity and selectivity was affected both by the hydrophobicity of the solvent and the substrate.

  3. Recent Advances in Enzymatic Fuel Cells: Experiments and Modeling

    Directory of Open Access Journals (Sweden)

    Ivan Ivanov

    2010-04-01

    Full Text Available Enzymatic fuel cells convert the chemical energy of biofuels into electrical energy. Unlike traditional fuel cell types, which are mainly based on metal catalysts, the enzymatic fuel cells employ enzymes as catalysts. This fuel cell type can be used as an implantable power source for a variety of medical devices used in modern medicine to administer drugs, treat ailments and monitor bodily functions. Some advantages in comparison to conventional fuel cells include a simple fuel cell design and lower cost of the main fuel cell components, however they suffer from severe kinetic limitations mainly due to inefficiency in electron transfer between the enzyme and the electrode surface. In this review article, the major research activities concerned with the enzymatic fuel cells (anode and cathode development, system design, modeling by highlighting the current problems (low cell voltage, low current density, stability will be presented.

  4. Enzymatic saccharification of brown seaweed for production of fermentable sugars.

    Science.gov (United States)

    Sharma, Sandeep; Horn, Svein Jarle

    2016-08-01

    This study shows that high drying temperatures negatively affect the enzymatic saccharification yield of the brown seaweed Saccharina latissima. The optimal drying temperature of the seaweed in terms of enzymatic sugar release was found to be 30°C. The enzymatic saccharification process was optimized by investigating factors such as kinetics of sugar release, enzyme dose, solid loading and different blend ratios of cellulases and an alginate lyase. It was found that the seaweed biomass could be efficiently hydrolysed to fermentable sugars using a commercial cellulase cocktail. The inclusion of a mono-component alginate lyase was shown to improve the performance of the enzyme blend, in particular at high solid loadings. At 25% dry matter loading a combined glucose and mannitol concentration of 74g/L was achieved. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Green liquor pretreatment for improving enzymatic hydrolysis of corn stover.

    Science.gov (United States)

    Gu, Feng; Yang, Linfeng; Jin, Yongcan; Han, Qiang; Chang, Hou-min; Jameel, Hasan; Phillips, Richard

    2012-11-01

    Green liquor consists of sodium carbonate and sodium sulfide and is readily available in any kraft mills. The green liquor pretreatment process for bioethanol production was developed for wood chips. This process uses only proven technology and equipment currently used in a kraft pulp mill and has several additional advantages such as high sugar recovery and concentration, no inhibitive substances produced, as compared to acid-based pretreatment methods. The liquor was used to pretreat corn stover for enhancing enzymatic hydrolysis in bioethanol production. Pulp yield of 70% with 45% lignin removal was achieved under optimized conditions (8% total titratable alkali, 40% sulfidity and 140°C). About 70% of the original polysaccharides were converted into fermentable sugars, using 20 FPU/g-pulp of enzyme in the subsequent enzymatic hydrolysis. The result indicates that green liquor is a feasible pretreatment to improve the enzymatic saccharification of corn stover for bioethanol production. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Oxidative stress signaling to chromatin in health and disease

    KAUST Repository

    Kreuz, Sarah

    2016-06-20

    Oxidative stress has a significant impact on the development and progression of common human pathologies, including cancer, diabetes, hypertension and neurodegenerative diseases. Increasing evidence suggests that oxidative stress globally influences chromatin structure, DNA methylation, enzymatic and non-enzymatic post-translational modifications of histones and DNA-binding proteins. The effects of oxidative stress on these chromatin alterations mediate a number of cellular changes, including modulation of gene expression, cell death, cell survival and mutagenesis, which are disease-driving mechanisms in human pathologies. Targeting oxidative stress-dependent pathways is thus a promising strategy for the prevention and treatment of these diseases. We summarize recent research developments connecting oxidative stress and chromatin regulation.

  7. Transition-state structures for enzymatic and alkaline phosphotriester hydrolysis

    International Nuclear Information System (INIS)

    Caldwell, S.R.; Raushel, F.M.; Weiss, P.M.; Cleland, W.W.

    1991-01-01

    The primary and secondary 18 O isotope effects for the alkaline (KOH) and enzymatic (phosphotriesterase) hydrolysis of two phosphotriesters, O,O-diethyl p-nitrophenyl phosphate (I) and O,O-diethyl O-(4-carbamoylphenyl) phosphate (II), are consistent with an associative mechanism with significant changes in bond order to both the phosphoryl and phenolic leaving group oxygens in the transition state. The synthesis of [ 15 N, phosphoryl- 18 O]-,[ 15 N, phenolic- 18 O]-, and [ 15 N]-O,O-diethyl p-nitrophenyl phosphate and O,O-diethyl O-(4-carbamoylphenyl)phosphate is described. The primary and secondary 18 O isotope effects for the alkaline hydrolysis of compound I are 1.0060 and 1.0063 ± 0.0001, whereas for compound II they are 1.027±0.002 and 1.025 ± 0.002, respectively. These isotope effects are consistent with the rate-limiting addition of hydroxide and provide evidence for a S N 2-like transition state with the absence of a stable phosphorane intermediate. For the enzymatic hydrolysis of compound I, the primary and secondary 18 O isotope effects are very small, 1.0020 and 1.0021±0.0004, respectively, and indicate that the chemical step in the enzymatic mechanism is not rate-limiting. The 18 O isotope effects for the enzymatic hydrolysis of compound II are 1.036±0.001 and 1.0181±0.0007, respectively, and are comparable in magnitude to the isotope effects for alkaline hydrolysis, suggesting that the chemical step is rate-limiting. The relative magnitude of the primary 18 O isotope effects for the alkaline and enzymatic hydrolysis of compound II reflect a transition state that is more progressed for the enzymatic reaction

  8. Management of oxidative stress by microalgae.

    Science.gov (United States)

    Cirulis, Judith T; Scott, J Ashley; Ross, Gregory M

    2013-01-01

    The aim of this review is to provide an overview of the current research on oxidative stress in eukaryotic microalgae and the antioxidant compounds microalgae utilize to control oxidative stress. With the potential to exploit microalgae for the large-scale production of antioxidants, interest in how microalgae manage oxidative stress is growing. Microalgae can experience increased levels of oxidative stress and toxicity as a result of environmental conditions, metals, and chemicals. The defence mechanisms for microalgae include antioxidant enzymes such as superoxide dismutase, catalase, peroxidases, and glutathione reductase, as well as non-enzymatic antioxidant molecules such as phytochelatins, pigments, polysaccharides, and polyphenols. Discussed herein are the 3 areas the literature has focused on, including how conditions stress microalgae and how microalgae respond to oxidative stress by managing reactive oxygen species. The third area is how beneficial microalgae antioxidants are when administered to cancerous mammalian cells or to rodents experiencing oxidative stress.

  9. Synthesis, spectroscopic characterization, DNA interaction and biological activities of Mn(II), Co(II), Ni(II) and Cu(II) complexes with [(1H-1,2,4-triazole-3-ylimino)methyl]naphthalene-2-ol

    Science.gov (United States)

    Gaber, Mohamed; El-Wakiel, Nadia A.; El-Ghamry, Hoda; Fathalla, Shaimaa K.

    2014-11-01

    Manganese(II), cobalt(II), nickel(II) and copper(II) complexes of [(1H-1,2,4-triazole-3-ylimino)methyl]naphthalene-2-ol have been synthesized. The structure of complexes have been characterized by elemental analysis, molar conductance, magnetic moment measurements and spectral (IR, 1H NMR, EI-mass, UV-Vis and ESR), and thermal studies. The results showed that the chloro and nitrato Cu(II) complexes have octahedral geometry while Ni(II), Co(II) and Mn(II) complexes in addition to acetato Cu(II) complex have tetrahedral geometry. The possible structures of the metal complexes have been computed using the molecular mechanic calculations using the hyper chem. 8.03 molecular modeling program to confirm the proposed structures. The kinetic and thermodynamic parameters of the thermal decomposition steps were calculated from the TG curves. The binding modes of the complexes with DNA have been investigated by UV-Vis absorption titration. The results showed that the mode of binding of the complexes to DNA is intercalative or non-intercalative binding modes. Schiff base and its metal complexes have been screened for their in vitro antimicrobial activities against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli and Pesudomonas aeruginosa), fungi (Asperigllus flavus and Mucer) and yeast (Candida albicans and Malassezia furfur).

  10. Synthesis, Characterization, and Biological Activity of Mn(II, Fe(II, Co(II, Ni(II, Cu(II, Zn(II, and Cd(II Complexes of N-Thiophenoyl-N′-Phenylthiocarbohydrazide

    Directory of Open Access Journals (Sweden)

    M. Yadav

    2013-01-01

    Full Text Available Mn(II, Fe(II, Co(II, Ni(II, Cu(II, Zn(II, and Cd(II complex of N-thiophenoyl -N′-phenylthiocarbohydrazide (H2 TPTH have been synthesized and characterized by elemental analysis, magnetic susceptibility measurements, infrared, NMR, electronic, and ESR spectral studies. The complexes were found to have compositions [Mn(H TPTH2], [Co(TPTH (H2O2], [Ni(TPTH (H2O2], [Cu(TPTH], [Zn(H TPTH], [Cd(H TPTH2], and [Fe(H TPTH2(EtOH]. The magnetic and electronic spectral studies suggest square planar geometry for [Cu(TPTH], tetrahedral geometry for [Zn(TPTH] and [Cd(H TPTH2], and octahedral geometry for rest of the complexes. The infrared spectral studies of the 1 : 1 deprotonated complexes suggest bonding through enolic oxygen, thiolato sulfur, and both the hydrazinic nitrogens. Thus, H2TPTH acts as a binegative tetradentate ligand. H2 TPTH and its metal complexes have been screened against several bacteria and fungi.

  11. Therapeutic effectiveness of a new enzymatic bleaching dentifrice.

    Science.gov (United States)

    Forner, Leopaldo; Amengual, José; Liena, Carmen; Riutord, Pere

    2012-01-01

    Research into bleaching focuses on new products in order to minimize undesirable effects. This study evaluated the bleaching effectiveness of a new enzymatic-activated dentifrice. A total of 20 volunteers were bleached with a dentifrice containing 5% lactoperoxidase and 3% carbamide peroxide applied three times a day for two minutes over 21 days. Color was recorded before and after the treatment using a spectrophotometer. CIELAB differences were calculated before and after treatment using the paired t test (P whitening teeth. Enzymatic dental bleaching is able to increase the efficiency of low concentration peroxides, reducing the potential risk of peroxides on oral tissues.

  12. Optimization of Substrate Feeding for Enzymatic Biodiesel Production

    DEFF Research Database (Denmark)

    Price, Jason Anthony; Huusom, Jakob Kjøbsted; Nordblad, Mathias

    to be effective in mitigating the effects of substrate inhibition. Using enzymatic biodiesel production as a case study, the volumetric productivity of the reactor is increased while minimizing inactivation of the enzyme due to the alcohol. This is done by using a simple optimization routine where the substrate...... (both the vegetable oil and alcohol) feed rate/concentration is manipulated simultaneously. The results of the simulation were tested in the laboratory and are sufficiently positive to suggest the implementation of a feeding strategy for large scale enzymatic biodiesel production....

  13. Moving towards a Competitive Fully Enzymatic Biodiesel Process

    Directory of Open Access Journals (Sweden)

    Silvia Cesarini

    2015-06-01

    Full Text Available Enzymatic biodiesel synthesis can solve several problems posed by the alkaline-catalyzed transesterification but it has the drawback of being too expensive to be considered competitive. Costs can be reduced by lipase improvement, use of unrefined oils, evaluation of soluble/immobilized lipase preparations, and by combination of phospholipases with a soluble lipase for biodiesel production in a single step. As shown here, convenient natural tools have been developed that allow synthesis of high quality FAMEs (EN14214 from unrefined oils in a completely enzymatic single-step process, making it fully competitive.

  14. Dynamic modeling and validation of a lignocellulosic enzymatic hydrolysis process

    DEFF Research Database (Denmark)

    Prunescu, Remus Mihail; Sin, Gürkan

    2013-01-01

    The enzymatic hydrolysis process is one of the key steps in second generation biofuel production. After being thermally pretreated, the lignocellulosic material is liquefied by enzymes prior to fermentation. The scope of this paper is to evaluate a dynamic model of the hydrolysis process...... on a demonstration scale reactor. The following novel features are included: the application of the Convection–Diffusion–Reaction equation to a hydrolysis reactor to assess transport and mixing effects; the extension of a competitive kinetic model with enzymatic pH dependency and hemicellulose hydrolysis...

  15. Optimization of Substrate Feeding for Enzymatic Biodiesel Production

    DEFF Research Database (Denmark)

    Price, Jason Anthony; Huusom, Jakob Kjøbsted; Nordblad, Mathias

    2013-01-01

    to be effective in mitigating the effects of substrate inhibition. Using enzymatic biodiesel production as a case study, the volumetric productivity of the reactor is increased while minimizing inactivation of the enzyme due to the alcohol. This is done by using a simple optimization routine where the substrate...... (both the vegetable oil and alcohol) feed rate/concentration is manipulated simultaneously. The results of the simulation were tested in the laboratory and are sufficiently positive to suggest the implementation of a feeding strategy for large scale enzymatic biodiesel production....

  16. Enzymatic generation of hydrogen peroxide shows promising antifouling effect

    DEFF Research Database (Denmark)

    Kristensen, J.B.; Olsen, Stefan Møller; Laursen, B.S.

    2010-01-01

    The antifouling (AF) potential of hydrogen peroxide (H2O2) produced enzymatically in a coating containing starch, glucoamylase, and hexose oxidase was evaluated in a series of laboratory tests and in-sea field trials. Dissolved H2O2 inhibited bacterial biofilm formation by eight of nine marine...... Proteobacteria, tested in microtiter plates. However, enzymatically produced H2O2 released from a coating did not impede biofilm formation by bacteria in natural seawater tested in a biofilm reactor. A field trial revealed a noticeable effect of the enzyme system: after immersion in the North Sea for 97 days...

  17. High Performance Non-enzymatic Glucose Sensor Based on One-Step Electrodeposited Nickel Sulfide.

    Science.gov (United States)

    Kannan, Padmanathan Karthick; Rout, Chandra Sekhar

    2015-06-22

    Nanostructured NiS thin film was prepared by a one-step electrodeposition method and the structural, morphological characteristics of the as-prepared films were analyzed by X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The electrocatalytic activity of NiS thin film towards glucose oxidation was investigated by fabricating a non-enzymatic glucose sensor and the sensor performance was studied by cyclic voltammetry (CV) and amperometry. The fabricated sensor showed excellent sensitivity and low detection limit with values of 7.43 μA μM(-1)  cm(-2) and 0.32 μM, respectively, and a response time of <8 s. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Enzymatic Reactions in Near Critical CO2: The Effect of Pressure on Phenol Removal by Tyrosinase

    Science.gov (United States)

    Amaral, Priscilla; Garcia, Daniela; Cardoso, Miguel; Mendes, Marisa; Coelho, Maria Alice; Pessoa, Fernando

    2009-01-01

    The use of enzymes in supercritical CO2 (SCCO2) has received extensive attention in recent years. Biocatalysts have the advantage of substrate specificity and SCCO2 offers several advantages over liquid solvents. This work deals with the utilization of SCCO2 as a medium for the enzymatic removal of phenol from aqueous solutions using tyrosinase. Since the presence of oxygen is crucial for the enzyme-catalyzed oxidation, the substantial solvating power of SCCO2 makes it a promising medium for such reactions. The conversion of phenol was higher at 10 MPa. Under near critical conditions (7 MPa, 35 °C), the addition of air at 5 × 105 Pa of pressure improved phenol removal. PMID:20054468

  19. Efficient Enzymatic Synthesis of Phenolic Ester by Increasing Solubility of Phenolic Acids in Ionic Liquids

    DEFF Research Database (Denmark)

    Yang, Zhiyong; Guo, Zheng; Xu, Xuebing

    Compounds from phenolic acid family are well known natural antioxidants, but the application of phenolic acids as antioxidants in industry is limited due to the relatively low solubility in oil-based media. The properties of phenolic acids can be modified through enzymatic lipophilization...... and modified phenolic acids will have amphiphilic property, therefore they can be localized at oil-water or water-oil phase where oxidation is considered to occur frequently. It had been reported that immobilized Candida Antarctica lipase B was the most effective biocatalyst for the various esterification...... reactions, and it had been widely used for esterification of various phenolic acids with fatty alcohol or triglycerides. However, the conversion of phenolic acids is low due to low solubility in hydrophobic solvents and hindrance effect of unsaturated side chain towards the enzyme. Our studies show...

  20. Enzymatic synthesis of arbutin undecylenic acid ester and its inhibitory effect on mushroom tyrosinase.

    Science.gov (United States)

    Tokiwa, Y; Kitagawa, M; Raku, T

    2007-03-01

    A novel tyrosinase inhibitor, an arbutin derivative having undecylenic acid at the 6-position of its glucose moiety, was enzymatically synthesized. Its inhibitory activity was studied in vitro by using catechol and phenol as substrates. The IC(50) value of the arbutin ester on tyrosinase using catechol (4 x 10(-4) M) was 1% of that when arbutin (4 x 10(-2) M) was used. Using phenol, IC(50) of the arbutin ester (3 x 10(-4) M) as substrate was 10% of that of arbutin (3 x 10(-3) M). These results suggest that the arbutin ester inhibits the latter part of the tyrosinase reaction, which consists of hydroxylation and oxidation.

  1. Evaluation of alcohol dehydrogenase and aldehyde dehydrogenase enzymes as bi-enzymatic anodes in a membraneless ethanol microfluidic fuel cell

    Science.gov (United States)

    Galindo-de-la-Rosa, J.; Arjona, N.; Arriaga, L. G.; Ledesma-García, J.; Guerra-Balcázar, M.

    2015-12-01

    Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (AldH) enzymes were immobilized by covalent binding and used as the anode in a bi-enzymatic membraneless ethanol hybrid microfluidic fuel cell. The purpose of using both enzymes was to optimize the ethanol electro-oxidation reaction (EOR) by using ADH toward its direct oxidation and AldH for the oxidation of aldehydes as by-products of the EOR. For this reason, three enzymatic bioanode configurations were evaluated according with the location of enzymes: combined, vertical and horizontally separated. In the combined configuration, a current density of 16.3 mA cm-2, a voltage of 1.14 V and a power density of 7.02 mW cm-2 were obtained. When enzymes were separately placed in a horizontal and vertical position the ocp drops to 0.94 V and to 0.68 V, respectively. The current density also falls to values of 13.63 and 5.05 mA cm-2. The decrease of cell performance of bioanodes with separated enzymes compared with the combined bioanode was of 31.7% and 86.87% for the horizontal and the vertical array.

  2. Resveratrol and Endothelial Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Ning Xia

    2014-10-01

    Full Text Available Nitric oxide (NO derived from the endothelial NO synthase (eNOS has antihypertensive, antithrombotic, anti-atherosclerotic and antiobesogenic properties. Resveratrol is a polyphenol phytoalexin with multiple cardiovascular and metabolic effects. Part of the beneficial effects of resveratrol are mediated by eNOS. Resveratrol stimulates NO production from eNOS by a number of mechanisms, including upregulation of eNOS expression, stimulation of eNOS enzymatic activity and reversal of eNOS uncoupling. In addition, by reducing oxidative stress, resveratrol prevents oxidative NO inactivation by superoxide thereby enhancing NO bioavailability. Molecular pathways underlying these effects of resveratrol involve SIRT1, AMPK, Nrf2 and estrogen receptors.

  3. Enzymatic detection of formalin-fixed museum specimens for DNA analysis and enzymatic maceration of formalin-fixed specimens

    DEFF Research Database (Denmark)

    Sørensen, Margrethe; Redsted Rasmussen, Arne; Simonsen, Kim Pilkjær

    2016-01-01

    Abstract.—A simple enzymatic screening method has been developed to detect whether a tissue sample has been preserved with formalin or with ethanol only because such a method is a useful tool for predicting the quality of genetic test results. The method is based on enzymatic digestion at 55 C...... in museums where DNA analyses of archived specimens are performed. Wasted time and resources can be avoided through the detection of formalin-fixed specimens because these specimens yield low-quality, damaged DNA. In addition to the screening method, it is shown that formalin-preserved specimens can...

  4. Changes in Non-Enzymatic Antioxidants in the Blood Following Anaerobic Exercise in Men and Women.

    Directory of Open Access Journals (Sweden)

    Magdalena Wiecek

    Full Text Available The aim of this study was to compare changes in total oxidative status (TOS, total antioxidative capacity (TAC and the concentration of VitA, VitE, VitC, uric acid (UA, reduced (GSH and oxidized glutathione (GSSG in blood within 24 hours following anaerobic exercise (AnEx among men and women.10 women and 10 men performed a 20-second bicycle sprint (AnEx. Concentrations of oxidative stress indicators were measured before AnEx and 3, 15 and 30 minutes and 1 hour afterwards. UA, GSH and GSSH were also measured 24 hours after AnEx. Lactate and H+ concentrations were measured before and 3 minutes after AnEx.The increase in lactate and H+ concentrations following AnEx was similar in both sexes. Changes in the concentrations of all oxidative stress indicators were significant and did not differ between men and women. In both sexes, TOS, TAC, TOS/TAC and VitA and VitE concentrations were the highest 3 minutes, VitC concentration was the highest 30 minutes, and UA concentration was the highest 1 hour after AnEx. GSH concentration was significantly lower than the initial concentration from 15 minutes to 24 hour after AnEx. GSSG concentration was significantly higher, while the GSH/GSSG ratio was significantly lower than the initial values 1 hour and 24 hour after AnEx.With similar changes in lactate and H+ concentrations, AnEx induces the same changes in TAC, TOS, TOS/TAC and non-enzymatic antioxidants of low molecular weight in men and women. Oxidative stress lasted at least 24 hours after AnEx.

  5. Physiological and enzymatic changes in rice seeds stored at low ...

    African Journals Online (AJOL)

    This study aimed to evaluate the effect of low temperatures on the physiological and enzymatic changes of rice seeds. The seeds were packed in airtight chambers and maintained at temperatures of 8 and -50°C for periods of 15, 30 , 45, 60, 75 and 90 days. The same procedure was adopted for the control treatment with ...

  6. Enzymatic activities of Dermatophilus congolensis measured by API ZYM.

    Science.gov (United States)

    Hermoso de Mendoza, J; Arenas, A; Alonso, J M; Rey, J M; Gil, M C; Anton, J M; Hermoso de Mendoza, M

    1993-10-01

    API ZYM kit was used to test enzymatic activities on eighteen strains of Dermatophilus congolensis. All strains produced lipase and acid phosphatase, which act on lipids, and leucine arylamidase which act on proteins. Another 10 exoenzymes were present in at least one of the strains.

  7. PDGF ENZYMATIC ACTIVITY IN PATIENTS WITH DELAYED FRACTURE CONSOLIDATION

    Directory of Open Access Journals (Sweden)

    D. V. Kuzmenko

    2017-01-01

    Full Text Available Introduction. Techniques that use growth factors to improve bone fragment consolidation and to treat the inflammatory and degenerative diseases of the musculoskeletal system have become very popular. Many researchers are actively searching for personification of this therapy and the reasons for delayed consolidation. The purpose of the study – to identify the biomarker for delayed bone consolidation.Materials and Methods. The study groups consisted of patients with high-energy tibia open fractures with normal (group 1 and with delayed (2nd group consolidation of bone fragments. The enzymatic activity of platelet-derived growth factor (PDGF in blood serum was studied after 7 days and in 1, 3 and 6 months after bone fragments reduction. Spectrophotometric technique (Specord-200 was used.Results. In patients with normal consolidation of bone fragments, the enzymatic activity of PDGF was statistically significantly higher in comparison with the group with delayed healing. At the same time, the highest activity was reported on day 7, and by third month it was becoming lower.Conclusion. Bone healing depends on PDGF enzymatic activity, besides significant differences on various stages of healing were observed. Further study the reasons for the PDGF enzymatic deficiency and its correction are of a great interest for reducing the timing of consolidation.

  8. Lime pretreatment and fermentation of enzymatically hydrolyzed sugarcane bagasse.

    Science.gov (United States)

    Rabelo, Sarita C; Maciel Filho, Rubens; Costa, Aline C

    2013-03-01

    Sugarcane bagasse was subjected to lime (calcium hydroxide) pretreatment and enzymatic hydrolysis for second-generation ethanol production. A central composite factorial design was performed to determine the best combination of pretreatment time, temperature, and lime loading, as well as to evaluate the influence of enzymatic loadings on hydrolysis conversion. The influence of increasing solids loading in the pretreatment and enzymatic hydrolysis stages was also determined. The hydrolysate was fermented using Saccharomyces cerevisiae in batch and continuous mode. In the continuous fermentation, the hydrolysates were concentrated with molasses. Lime pretreatment significantly increased the enzymatic digestibility of sugarcane bagasse without the need for prior particle size reduction. In the optimal pretreatment conditions (90 h, 90 °C, 0.47 glime/g bagasse) and industrially realistic conditions of hydrolysis (12.7 FPU/g of cellulase and 7.3 CBU/g of β-glucosidase), 139.6 kglignin/ton raw bagasse and 126.0 kg hemicellulose in the pretreatment liquor per ton raw bagasse were obtained. The hydrolysate from lime pretreated sugarcane bagasse presented low amounts of inhibitors, leading to ethanol yield of 164.1 kgethanol/ton raw bagasse.

  9. Wet explosion pretreatment of sugarcane bagasse for enhanced enzymatic hydrolysis

    DEFF Research Database (Denmark)

    Biswas, Rajib; Uellendahl, Hinrich; Ahring, Birgitte Kiær

    2014-01-01

    Wet explosion pretreatment of sugarcane bagasse was investigated in pilot-scale with the aim of obtaining the highest possible sugar yield after pretreatment. The temperatures used were 155, 170, 185 and 200 C with or without addition of oxygen (0.6 MPa pressure). Enzymatic hydrolysis of washed...

  10. Soil bacterial flora and enzymatic activities in zinc and lead ...

    African Journals Online (AJOL)

    JTEkanem

    Abstract. Soil bacterial flora and enzymatic activities in lead and zinc contaminated soil of Ishiagu, ... the quality of the soil. The type of activities prevalent in any given environment determines the type of contamination in that area1-3. Soil and water bodies have been sinks for many ..... lead, Cadmium and Mercury in cattle.

  11. Highly Stable Foams from Block Oligomers Synthesized by Enzymatic Reactions

    NARCIS (Netherlands)

    Sagis, L.M.C.; Boeriu, C.G.; Frissen, A.E.; Schols, H.A.; Wierenga, P.A.

    2008-01-01

    We have synthesized a new amphiphilic block oligomer by the enzymatic linking of a fatty acid (lauric acid) to a fructan oligomer (inulin) and tested the functionality of this carbohydrate derivative in foam stabilization. The structure of the modified oligosaccharide was found to be

  12. Enzymatic cascade reactions involving phosphorylated intermediates: immobilization and process optimization

    NARCIS (Netherlands)

    Babich, L.

    2013-01-01

    The research described in this thesis aims to develop new strategies for the synthesis of fine chemicals by replacing conventional methods by nature-inspired technologies. The integration of multiple enzymatic steps into one-pot cascade processes is the ultimate goal to convert cheap renewable

  13. Process design for enzymatic Adipyl-7-ADCA hydrolysis

    NARCIS (Netherlands)

    Schroën, Catharina Gerarda Petronella Henrica; Nierstrasz, Vincent; Bosma, Rouke; Dijkstra, Zwaantje Johanna; VandeSandt, Emilius Johannes Albertus Xavierius; Beeftink, Hendrik Harmen; Tramper, Johannes

    2002-01-01

    Adipyl-7-ADCA is a new source for 7-aminodeacetoxycephalosporanic acid (7-ADCA), one of the substrates for antibiotics synthesis. In this paper, a novel process for enzymatic 7-ADCA production is presented. The process consists of a reactor, a crystallization step, a membrane separation step, and

  14. Validation of Orchestia gammarellus enzymatic activities in several ...

    African Journals Online (AJOL)

    The aim of this research was to validate the enzymatic activities (catalase, esterase, á-amylase and acetylcholinesterase) of Orchestia gammarellus in several sites of Tangier's bay to improve predictive performance of responses to coastal environmental pollutants. Our results showed a significant increase of catalase (e.g. ...

  15. Evaluation of microbial and enzymatic communities in soil and ...

    African Journals Online (AJOL)

    Evaluation of microbial and enzymatic communities in soil and rizosphere from soybean plants. M.S. Santos, E.S.D. Villela, R.A.A. Pazianotto, E.F. Reynaldo, E.H.F.M. Silva, A.C.S.O. Bueno, A. May ...

  16. Functional palm oil-based margarine by enzymatic interesterification

    DEFF Research Database (Denmark)

    Ibrahim, Nuzul Amri Bin; Xu, Xuebing

    Palm stearin, palm kernel and fish oils were blended to a various composition ratios and enzymatically interesterified by Lipozyme TL IM lipase (Thermomyces lanuginosa) using a continuous packed bed reactor. The ratio of the oils ranged from 60-90%, 10-40% and 0-10% respectively. The enzyme...

  17. Enzymatic cell disruption of microalgae biomass in biorefinery processes.

    Science.gov (United States)

    Demuez, Marie; Mahdy, Ahmed; Tomás-Pejó, Elia; González-Fernández, Cristina; Ballesteros, Mercedes

    2015-10-01

    When employing biotechnological processes for the procurement of biofuels and bio-products from microalgae, one of the most critical steps affecting economy and yields is the "cell disruption" stage. Currently, enzymatic cell disruption has delivered effective and cost competitive results when compared to mechanical and chemical cell disruption methods. However, the introduction of enzymes implies additional associated cost within the overall process. In order to reduce this cost, autolysis of microalgae is proposed as alternative enzymatic cell disruption method. This review aims to provide the state of the art of enzymatic cell disruption treatments employed in biorefinery processes and highlights the use of endopeptidases. During the enzymatic processes of microalgae life cycle, some lytic enzymes involved in cell division and programmed cell death have been proven useful in performing cell lysis. In this context, the role of endopeptidases is emphasized. Mirroring these natural events, an alternative cell disruption approach is proposed and described with the potential to induce the autolysis process using intrinsic cell enzymes. Integrating induced autolysis within biofuel production processes offers a promising approach to reduce overall global costs and energetic input associated with those of current cell disruption methods. A number of options for further inquiry are also discussed. © 2015 Wiley Periodicals, Inc.

  18. Enzymatic biodiesel production from sludge palm oil (SPO) using ...

    African Journals Online (AJOL)

    Biodiesel is a non-toxic, renewable and environmental friendly fuel. This study involved the production of biodiesel from sludge palm oil (SPO), a low-cost waste oil via enzymatic catalysis. The enzyme catalyst was a Candida cylindracea lipase, locally-produced using palm oil mill effluent as the low cost based medium.

  19. Enzymatic epoxidation of biodiesel optimized by response surface ...

    African Journals Online (AJOL)

    During the enzymatic epoxidation of biodiesel, stearic acid was selected as oxygen carrier. Enzyme screening and the load of stearic acid were investigated. The effects of four main reaction conditions including reaction time, temperature, enzyme load, and mole ratio of H2O2/C=C-bonds on the epoxy oxygen group content ...

  20. A comparison of acidic and enzymatic hydrolysis of rutin | Wang ...

    African Journals Online (AJOL)

    Rutin and its hydrolysis products (isoquercitrin and quercetin) are widely used as important materials in food and pharmaceutical industry. In this study, the effects of various acids and enzymes as catalysts on the hydrolysis reaction of rutin were studied. In comparison with acidic and enzymatic catalysis of rutin, the research ...

  1. Robust and efficient enzymatic saccharification of softwoods by SPORL

    Science.gov (United States)

    J.Y. Zhu; X.J. Pan; W. Zhu; G.S. Wang; R. Gleisner

    2009-01-01

    This study demonstrated Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose (SPORL) for robust conversion of softwood through enzymatic hydrolysis. At a sodium bisulfite charge around 9%, over 90% cellulose conversion could be achieved when spruce wood chips were pretreated at 180°C with pH near 2. For lodgepole pine, pretreatment liquor initial...

  2. Short-time ultrasonication treatment in enzymatic hydrolysis of biomass

    Science.gov (United States)

    Zengqian Shi; Zhiyong Cai; Siqun Wang; Qixin Zhong; Joseph J. Bozell

    2013-01-01

    To improve the conversion of enzymatic hydrolysis of biomass in an energy-efficient manner, two shorttime ultrasonication strategies were applied on six types of biomass with different structures and components. The strategies include pre-sonication before the hydrolysis and intermittent sonication during the ongoing hydrolysis. The microstructures of each type of...

  3. Recombinant EXLX1 from Bacillus subtilis for enhancing enzymatic ...

    African Journals Online (AJOL)

    AJL

    2012-06-21

    Jun 21, 2012 ... enhancing enzymatic hydrolysis of corn stover with low cellulase loadings. Zhang Yan1, He Ming-Xiong2,3*, Wu Bo1, ... University, Chengdu 610064, China. 2Biogas Institute of Ministry of Agriculture, Biomass Energy Technology Research Centre, Section 4-13, Renming Nanlu,. Chengdu 610041, China.

  4. Enzymatic Profiles of Activated Sludge from a Wastewater Treatment ...

    African Journals Online (AJOL)

    Activated sludge samples collected from a treatment plant, with foaming experience in the month of July, was characterized enzymatically. Hexokinase, Glyceraldehyde-3-phosphate dehydrogenase and Adenylate kinase activity assays were conducted before, during and after the foaming episode. The spectrum of enzyme ...

  5. Enzymatic Breakdown of Type II Collagen in the Human Vitreous

    NARCIS (Netherlands)

    van Deemter, Marielle; Pas, Hendri H.; Kuijer, Roel; van der Worp, Roelofje J.; Hooymans, Johanna M. M.; Los, Leonoor I.

    2009-01-01

    PURPOSE. To investigate whether enzymatic collagen breakdown is an active process in the human vitreous. METHODS. Human donor eyes were used for immunohistochemistry to detect the possible presence of the matrix metalloproteinase (MMP)-induced type II collagen breakdown product col2-3/4C-short in

  6. Malondialdehyde level and some enzymatic activities in subclinical ...

    African Journals Online (AJOL)

    The purpose of this study was to evaluate the changes occurring in milk malondialdehyde (MDA) level and some enzymatic activities as a result of subclinical mastitis (SCM) in dairy cows. A total of 124 milk samples were collected from 124 lactating cows from the same herd in the period between the 2nd week after calving ...

  7. Enzymatic saccharification of some agro-industrial cellulosic wastes ...

    African Journals Online (AJOL)

    Enzymatic saccharification of some agro-industrial cellulosic wastes by cellulose produced from a mixed culture of Aspergillus Niger and Saccharomyces ... All the sorghum pomace media recorded significantly (P<0.05) higher level of cellulase enzyme (2.06-4.06 units/ml) than that of carboxymethyl-cellulose medium (1.72 ...

  8. Enzymatic characterization of lipid-based drug delivery systems

    DEFF Research Database (Denmark)

    Ljusberg-Wahren, Helena; Seier Nielsen, Flemming; Brogård, Mattias

    2005-01-01

    The present work introduces a simple and robust in vitro method for enzymatic characterisation of surface properties of lipid dispersions in aqueous media. The initial lipolysis rate in biorelevant media, using pancreatic lipase and a self-microemulsifying formulation (SMEDDS) containing digestib...

  9. Recombinant EXLX1 from Bacillus subtilis for enhancing enzymatic ...

    African Journals Online (AJOL)

    Recombinant EXLX1 from Bacillus subtilis for enhancing enzymatic hydrolysis of corn stover with low cellulase loadings. ... These results provided a feasible way for the potential application of BsEXLX1 in the efficient saccharification of cellulose materials for bioethanol production. Key word: Bacillus subtilis, BsEXLX1, ...

  10. Enzymatic reaction paths as determined by transition path sampling

    Science.gov (United States)

    Masterson, Jean Emily

    Enzymes are biological catalysts capable of enhancing the rates of chemical reactions by many orders of magnitude as compared to solution chemistry. Since the catalytic power of enzymes routinely exceeds that of the best artificial catalysts available, there is much interest in understanding the complete nature of chemical barrier crossing in enzymatic reactions. Two specific questions pertaining to the source of enzymatic rate enhancements are investigated in this work. The first is the issue of how fast protein motions of an enzyme contribute to chemical barrier crossing. Our group has previously identified sub-picosecond protein motions, termed promoting vibrations (PVs), that dynamically modulate chemical transformation in several enzymes. In the case of human heart lactate dehydrogenase (hhLDH), prior studies have shown that a specific axis of residues undergoes a compressional fluctuation towards the active site, decreasing a hydride and a proton donor--acceptor distance on a sub-picosecond timescale to promote particle transfer. To more thoroughly understand the contribution of this dynamic motion to the enzymatic reaction coordinate of hhLDH, we conducted transition path sampling (TPS) using four versions of the enzymatic system: a wild type enzyme with natural isotopic abundance; a heavy enzyme where all the carbons, nitrogens, and non-exchangeable hydrogens were replaced with heavy isotopes; and two versions of the enzyme with mutations in the axis of PV residues. We generated four separate ensembles of reaction paths and analyzed each in terms of the reaction mechanism, time of barrier crossing, dynamics of the PV, and residues involved in the enzymatic reaction coordinate. We found that heavy isotopic substitution of hhLDH altered the sub-picosecond dynamics of the PV, changed the favored reaction mechanism, dramatically increased the time of barrier crossing, but did not have an effect on the specific residues involved in the PV. In the mutant systems

  11. Enzymatic biosensor of horseradish peroxidase immobilized on Au-Pt nanotube/Au-graphene for the simultaneous determination of antioxidants

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Long; Yin, Wenmin; Tang, Kun; Li, Dian; Shao, Kang; Zuo, Yunpeng; Ma, Jing; Liu, Jiawei; Han, Heyou, E-mail: hyhan@mail.hzau.edu.cn

    2016-08-24

    A new electrochemical method has been proposed for the simultaneous determination of butylated hydroxyanisole (BHA) and propyl gallate (PG) in food matrices based on enzymatic biosensors. Spiny Au-Pt nanotubes (SAP NTs) was first synthesized and demonstrated to exhibit intrinsic peroxidase and catalase-like activity. The structure of SAP NTs provides large surface area and favorable medium for electron transfer, on which HRP were immobilized and acted as enzymatic biosensor for the simultaneous detection of BHA and PG. The results revealed that BHA and PG both have well-defined oxidation waves with peak potentials of 624 and 655 mV, respectively. Under the optimal conditions, the method behaved satisfactory analytical performance towards BHA and PG with a wide linear range of 0.3–50 mg L{sup −1} and 0.1–100 mg L{sup −1}, as well as a detection limit of 0.046 mg L{sup −1} and 0.024 mg L{sup −1} (3σ/slope), respectively. Besides, the proposed method exhibits good sensitivity, stability and reproducibility, providing an alternative to fabricate electrode and construct sensitive biosensors. - Highlights: • SAP NTs was synthesized and demonstrated to exhibit intrinsic peroxidase and catalase-like activity. • The structure of SAP NTs provides larger surface area and more favorable medium for electron transfer. • Horseradish peroxidase immobilized on Au-Pt nanotube/Au-graphene acted as enzymatic biosensor. • The simultaneous detection of BHA and PG in food matrices was achieved based on enzymatic biosensors.

  12. Dynamic Simulation, Sensitivity and Uncertainty Analysis of a Demonstration Scale Lignocellulosic Enzymatic Hydrolysis Process

    DEFF Research Database (Denmark)

    Prunescu, Remus Mihail; Sin, Gürkan

    2014-01-01

    This study presents the uncertainty and sensitivity analysis of a lignocellulosic enzymatic hydrolysis model considering both model and feed parameters as sources of uncertainty. The dynamic model is parametrized for accommodating various types of biomass, and different enzymatic complexes...

  13. Comparison of dilute mineral and organic acid pretreatment for enzymatic hydrolysis of wheat straw

    NARCIS (Netherlands)

    Kootstra, A.M.J.; Beeftink, H.H.; Scott, E.L.; Sanders, J.P.M.

    2009-01-01

    The efficiencies of fumaric, maleic, and sulfuric acid in wheat straw pretreatment were compared. As a measure for pretreatment efficiency, enzymatic digestibility of the lignocellulose was determined. Monomeric glucose and xylose concentrations were measured after subsequent enzymatic hydrolysis,

  14. Antioxidant and oxidative stress status in type 2 diabetes and ...

    African Journals Online (AJOL)

    Objective. Oxidative stress (OS) has been implicated in the aetiology and progression of diabetic complications including diabetic foot ulcer. In this study, the levels of lipid peroxides (LPO) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) as well as the enzymatic antioxidant activities of superoxide dismutase (SOD) and ...

  15. Effect of ascorbic and folic acids supplementation on oxidative ...

    African Journals Online (AJOL)

    An experiment was conducted on the effect of supplementation of ascorbic and folic acids on the oxidative hormones, enzymatic antioxidants, haematological and biochemical properties of layers exposed to increased heat load. A total of 72 Isa Brown laying hens at 31 weeks of age were randomly divided into four groups ...

  16. Oxidative stress and antioxidant status in sportsmen two hours after ...

    African Journals Online (AJOL)

    Regular exercise has well documented health benefits. However, exercise can also induce imbalance between oxidant stress and antioxidant status. This study was designed to investigate the serum lipid profile and non-enzymatic antioxidants markers (serum uric acid and albumin) as well as lipid hydroperoxide (a marker ...

  17. Self-sustained enzymatic cascade for the production of 2,5-furandicarboxylic acid from 5-methoxymethylfurfural.

    Science.gov (United States)

    Carro, Juan; Fernández-Fueyo, Elena; Fernández-Alonso, Carmen; Cañada, Javier; Ullrich, René; Hofrichter, Martin; Alcalde, Miguel; Ferreira, Patricia; Martínez, Angel T

    2018-01-01

    2,5-Furandicarboxylic acid is a renewable building block for the production of polyfurandicarboxylates, which are biodegradable polyesters expected to substitute their classical counterparts derived from fossil resources. It may be produced from bio-based 5-hydroxymethylfurfural or 5-methoxymethylfurfural, both obtained by the acidic dehydration of biomass-derived fructose. 5-Methoxymethylfurfural, which is produced in the presence of methanol, generates less by-products and exhibits better storage stability than 5-hydroxymethylfurfural being, therefore, the industrial substrate of choice. In this work, an enzymatic cascade involving three fungal oxidoreductases has been developed for the production of 2,5-furandicarboxylic acid from 5-methoxymethylfurfural. Aryl-alcohol oxidase and unspecific peroxygenase act on 5-methoxymethylfurfural and its partially oxidized derivatives yielding 2,5-furandicarboxylic acid, as well as methanol as a by-product. Methanol oxidase takes advantage of the methanol released for in situ producing H 2 O 2 that, along with that produced by aryl-alcohol oxidase, fuels the peroxygenase reactions. In this way, the enzymatic cascade proceeds independently, with the only input of atmospheric O 2 , to attain a 70% conversion of initial 5-methoxymethylfurfural. The addition of some exogenous methanol to the reaction further improves the yield to attain an almost complete conversion of 5-methoxymethylfurfural into 2,5-furandicarboxylic acid. The synergistic action of aryl-alcohol oxidase and unspecific peroxygenase in the presence of 5-methoxymethylfurfural and O 2 is sufficient for the production of 2,5-furandicarboxylic acid. The addition of methanol oxidase to the enzymatic cascade increases the 2,5-furandicarboxylic acid yields by oxidizing a reaction by-product to fuel the peroxygenase reactions.

  18. Oxidative stress in cardiovascular diseases

    Directory of Open Access Journals (Sweden)

    Shyamal K Goswami

    2015-01-01

    Full Text Available Oxidative stress caused by various oxygen containing free radicals and reactive species (collectively called "Reactive Oxygen Species" or ROS has long been attributed to cardiovascular diseases. In human body, major oxidizing species are super oxide, hydrogen peroxide, hydroxyl radical, peroxy nitrite etc. ROS are produced from distinct cellular sources, enzymatic and non-enzymatic; have specific physicochemical properties and often have specific cellular targets. Although early studies in nineteen sixties and seventies highlighted the deleterious effects of these species, later it was established that they also act as physiological modulators of cellular functions and diseases occur only when ROS production is deregulated. One of the major sources of cellular ROS is Nicotinamide adenine dinucleotide phosphate oxidases (Noxes that are expressed in almost all cell types. Superoxide and hydrogen peroxide generated from them under various conditions act as signal transducers. Due to their immense importance in cellular physiology, various Nox inhibitors are now being developed as therapeutics. Another free radical of importance in cardiovascular system is nitric oxide (a reactive nitrogen species generated from nitric oxide synthase(s. It plays a critical role in cardiac function and its dysregulated generation along with superoxide leads to the formation of peroxynitrite a highly deleterious agent. Despite overwhelming evidences of association between increased level of ROS and cardiovascular diseases, antioxidant therapies using vitamins and omega 3 fatty acids have largely been unsuccessful till date. Also, there are major discrepancies between studies with laboratory animals and human trials. It thus appears that the biology of ROS is far complex than anticipated before. A comprehensive understanding of the redox biology of diseases is thus needed for developing targeted therapeutics.

  19. Archetypal sandwich-structured CuO for high performance non-enzymatic sensing of glucose

    Science.gov (United States)

    Meher, Sumanta Kumar; Rao, G. Ranga

    2013-02-01

    In the quest to enhance the selectivity and sensitivity of novel structured metal oxides for electrochemical non-enzymatic sensing of glucose, we report here a green synthesis of unique sandwich-structured CuO on a large scale under microwave mediated homogeneous precipitation conditions. The physicochemical studies carried out by XRD and BET methods show that the monoclinic CuO formed via thermal decomposition of Cu2(OH)2CO3 possesses monomodal channel-type pores with largely improved surface area (~43 m2 g-1) and pore volume (0.163 cm3 g-1). The fascinating surface morphology and pore structure of CuO is formulated due to homogeneous crystallization and microwave induced self assembly during synthesis. The cyclic voltammetry and chronoamperometry studies show diffusion controlled glucose oxidation at ~0.6 V (vs. Ag/AgCl) with extremely high sensitivity of 5342.8 μA mM-1 cm-2 and respective detection limit and response time of ~1 μM and ~0.7 s, under a wide dynamic concentration range of glucose. The chronoamperometry measurements demonstrate that the sensitivity of CuO to glucose is unaffected by the absence of dissolved oxygen and presence of poisoning chloride ions in the reaction medium, which essentially implies high poison resistance activity of the sandwich-structured CuO. The sandwich-structured CuO also shows insignificant interference/significant selectivity to glucose, even in the presence of high concentrations of other sugars as well as reducing species. In addition, the sandwich-structured CuO shows excellent reproducibility (relative standard deviation of ~2.4% over ten identically fabricated electrodes) and outstanding long term stability (only ~1.3% loss in sensitivity over a period of one month) during non-enzymatic electrochemical sensing of glucose. The unique microstructure and suitable channel-type pore architecture provide structural stability and maximum accessible electroactive surface for unimpeded mobility of glucose as well as the

  20. Determination of photosynthetic and enzymatic biomarkers sensitivity used to evaluate toxic effects of copper and fludioxonil in alga Scenedesmus obliquus

    International Nuclear Information System (INIS)

    Dewez, David; Geoffroy, Laure; Vernet, Guy; Popovic, Radovan

    2005-01-01

    Modulated PAM fluorometry and Plant Efficiency Analyser methods were used to investigate photosynthetic fluorescence parameters of alga Scenedesmus obliquus exposed to inhibitory effect of fungicides copper sulphate and fludioxonil (N-(4-nitrophenyl)-N'-propyl-uree). The change of those parameters were studied when alga S. obliquus have been exposed during 48 h to different concentrations of fungicides (1, 2 and 3 mg l -1 ). Under the same condition, enzymatic activities of catalase, ascorbate peroxidase, glutathione reductase and glutathione S-transferase were investigated to evaluate antioxidative response to fungicides effects. The change of sensitivity of those parameters was dependent to the mode of fungicide action, their concentration and time of exposure. For copper effects, the most indicative photosynthetic biomarkers were parameters Q N as non-photochemical fluorescence quenching, Q Emax as the proton induced fluorescence quenching and ABS/RC as the antenna size per photosystem II reaction center. Copper induced oxidative stress was indicated by increased activity of catalase serving as the most sensitive and valuable enzymatic biomarker. On the other hand, fludioxonil effect on photosynthetic parameters was very negligible and consequently not very useful as biomarkers. However, fludioxonil induced strong antioxidative activities associated with cytosol enzymes, as we found for catalase, ascorbate peroxidase and glutathione S-transferase activities. By obtained results, we may suggest for the activation of those enzymes to be sensitive and valuable biomarkers of oxidative stress induced by fludioxonil. Determination of biomarkers sensitivity may offer advantages in providing real criteria to use them for ecotoxicological diagnostic studies

  1. Highly Dispersed NiO Nanoparticles Decorating graphene Nanosheets for Non-enzymatic Glucose Sensor and Biofuel Cell

    Science.gov (United States)

    Zeng, Guisheng; Li, Weiping; Ci, Suqin; Jia, Jingchun; Wen, Zhenhai

    2016-11-01

    Nickel oxide-decorated graphene nanosheet (NiO/GNS), as a novel non-enzymatic electrocatalyst for glucose oxidation reaction (GOR), was synthesized through a facile hydrothermal route followed by the heat treatment. The successful synthesis of NiO/GNS was characterized by a series of techniques including XRD, BET, SEM and TEM. Significantly, the NiO/GNS catalyst show excellent catalytic activity toward GOR, and was employed to develop a sensitive non-enzymatic glucose sensor. The developed glucose sensor could response to glucose in a wide range from 5 μM-4.2 mM with a low detection limit (LOD) of 5.0 μM (S/N = 3). Importantly, compared with bare NiO, the catalytic activity of NiO/GNS was much higher. The reason might be that the 2D structure of graphene could prevent the aggregation of NiO and facilitate the electron transfer at electrode interface. Moreover, the outstanding catalytic activity of NiO/GNS was further demonstrated by applying it to construct a biofuel cell using glucose as fuel, which exhibited high stability and current density.

  2. Effects of lead contamination on soil enzymatic activities, microbial biomass, and rice physiological indices in soil-lead-rice (Oryza sativa L.) system.

    Science.gov (United States)

    Zeng, Lu S; Liao, Min; Chen, Cheng L; Huang, Chang Y

    2007-05-01

    The effect of lead (Pb) treatment on the soil enzymatic activities, soil microbial biomass, rice physiological indices and rice biomass were studied in a greenhouse pot experiment. Six levels of Pb viz. 0(CK), 100, 300, 500, 700, 900 mg/kg soil were applied in two types of paddy soils. The results showed that Pb treatment had a stimulating effect on soil enzymatic activities and microbial biomass carbon (Cmic) at low concentration and an inhibitory influence at higher concentration. The degree of influence on enzymatic activities and Cmic by Pb was related to the clay and organic matter contents of the soils. When the Pb treatment was raised to the level of 500 mg/kg, ecological risk appeared both to soil microorganisms and plants. The results also revealed a consistent trend of increased chlorophyll contents and rice biomass initially, maximum at a certain Pb treatment, and then decreased gradually with the increase in Pb concentration. Pb was effective in inducing proline accumulation and its toxicity causes oxidative stress in rice plants. Therefore, it was concluded that soil enzymatic activities, Cmic and rice physiological indices, could be sensitive indicators to reflect environmental stress in soil-lead-rice system.

  3. Enhancing the Antioxidant Ability of Trametes versicolor Polysaccharopeptides by an Enzymatic Hydrolysis Process.

    Science.gov (United States)

    Jhan, Mei-Hsin; Yeh, Ching-Hua; Tsai, Chia-Chun; Kao, Ching-Tian; Chang, Chao-Kai; Hsieh, Chang-Wei

    2016-09-10

    Polysaccharopeptides (PSPs) are among the main bioactive constituents of Trametes versicolor (T. versicolor). The purpose of this research was to investigate the antioxidant activities of enzymatic hydrolysates obtained from T. versicolor polysaccharopeptides by 80 U/mL β-1,3-glucanase (PSPs-EH80). The half-inhibitory concentration (IC50) of PSPs-EH80 in metal chelating assay, ABTS and DPPH radical scavenging test results were 0.83 mg/mL, 0.14 mg/mL and 0.52 mg/mL, respectively, which were lower than that of PSPs-EH 20 U/mL. The molecular weights of the PSPs-EH80 hydrolysates were 300, 190, 140 and 50 kDa, respectively, and the hydrolysis of polysaccharides by β-1,3-glucanase did not change the original functional group. PSPs-EH80 reduced the reactive oxygen species (ROS) content at least twice that of treatment without PSPs-EH80. In addition, an oxidative damage test showed that PSPs-EH80 can improve HaCaT cell survival. According to our results, PSP demonstrates the potential of anti-oxidative damage; besides, enzyme hydrolysis can improve the ability of the PSP.

  4. Determination of myoglobin based on its enzymatic activity by stopped-flow spectrophotometry

    Science.gov (United States)

    Zheng, Qi; Liu, Zhihong; Cai, Ruxiu

    2005-04-01

    A new method has been developed for the determination of myoglobin (Mb) based on its enzymatic activity for the oxidation of o-phenylenediamine (OPDA) with hydrogen peroxide. Stopped-flow spectrophotometry was used to study the kinetic behavior of the oxidation reaction. The catalytic activity of Mb was compared to other three kinds of catalyst. The time dependent absorbance of the reaction product, 2,3-diamimophenazine (DAPN), at a wavelength of 426 nm was recorded. The initial reaction rate obtained at 40 °C was found to be proportional to the concentration of Mb in the range of 1.0 × 10 -6 to 4.0 × 10 -9 mol L -1. The detection limit of Mb was found to be 9.93 × 10 -10 mol L -1. The relative standard deviations were within 5% for the determination of different concentrations of Mb. Excess of bovine serum albumin (BSA), Ca(II), Mg(II), Cu(II), glucose, caffeine, lactose and uric acid did not interfere.

  5. Biological activity of camel milk casein following enzymatic digestion.

    Science.gov (United States)

    Salami, Maryam; Moosavi-Movahedi, Ali Akbar; Moosavi-Movahedi, Faezeh; Ehsani, Mohammad Reza; Yousefi, Reza; Farhadi, Mohammad; Niasari-Naslaji, Amir; Saboury, Ali Akbar; Chobert, Jean-Marc; Haertlé, Thomas

    2011-11-01

    The aim of this study was to investigate the effects of enzymatic hydrolysis with digestive enzymes of camel whole casein and beta-casein (β-CN) on their antioxidant and Angiotensin Converting Enzyme (ACE)-inhibitory properties. Peptides in each hydrolysate were fractionated with ultra-filtration membranes. The antioxidant activity was determined using a Trolox equivalent antioxidant capacity (TEAC) scale. After enzymatic hydrolysis, both antioxidant and ACE-inhibitory activities of camel whole casein and camel β-CN were enhanced. Camel whole casein and β-CN showed significant ACE-inhibitory activities after hydrolysis with pepsin alone and after pepsinolysis followed by trypsinolysis and chymotrypsinolysis. Camel β-CN showed high antioxidant activity after hydrolysis with chymotrypsin. The results of this study suggest that when camel milk is consumed and digested, the produced peptides start to act as natural antioxidants and ACE-inhibitors.

  6. Pretreatment of Agave americana stalk for enzymatic saccharification.

    Science.gov (United States)

    Yang, Qiang; Pan, Xuejun

    2012-12-01

    Agave americana is one of commonly grown agave species but currently less valuable because its large flower stalk cannot be used for producing alcoholic beverage. In the present study, the stalk was pretreated with dilute acid (DA), sulfite (SPORL), and sodium hydroxide (NaOH) to preliminarily assess its potential as feedstock for bioethanol production. The changes of cell wall components during the pretreatments, enzymatic digestibility of the pretreated stalks, and the adsorption of cellulases on the substrates were investigated. Results indicated that the pretreatments significantly improved the enzymatic digestibility of the agave stalk. SPORL pretreatment gave higher substrate and sugar yields, while NaOH pretreated stalk had better digestibility under the investigated conditions. The better hydrolysability of NaOH-pretreated stalk was attributed to low lignin and hemicellulose content and high affinity to cellulases. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Enzymatic Assays to Investigate Acyl-Homoserine Lactone Autoinducer Synthases.

    Science.gov (United States)

    Shin, Daniel; Nagarajan, Rajesh

    2018-01-01

    Bacteria use chemical molecules called autoinducers as votes to poll their numerical strength in a colony. This polling mechanism, commonly referred to as quorum sensing, enables bacteria to build a social network and provide a collective response for fighting off common threats. In Gram-negative bacteria, AHL synthases synthesize acyl-homoserine lactone (AHL) autoinducers to turn on the expression of several virulent genes including biofilm formation, protease secretion, and toxin production. Therefore, inhibiting AHL signal synthase would limit quorum sensing and virulence. In this chapter, we describe four enzymatic methods that could be adopted to investigate a broad array of AHL synthases. The enzymatic assays described here should accelerate our mechanistic understanding of quorum-sensing signal synthesis that could pave the way for discovery of potent antivirulence compounds.

  8. Bio-based alkyds by direct enzymatic bulk polymerization

    DEFF Research Database (Denmark)

    Nguyen, Hiep Dinh

    materials before a 100% bio-based alkyd paint can be realized. In this project an enzyme catalyzed bulk polymerization method for direct production of alkyds has been developed. The objective has been to make it possible to produce binders at much lower temperatures as well as to achieve a higher degree....... Bio-based alkyds prepared from a combination of glycerol, and tall oil fatty acids, and azelaic acid by enzymatic polymerization show improved hydrophobicity and lower glass transition temperatures compared to an alkyd prepared from the same raw materials by a classical boiling method. The enzymatic...... working on the coupling between reinforcement agents and the binder in alkyd coatings. For this purpose, two different types of silica particles were modified with rape seed oil fatty acids or tall oil fatty acids (TOFA-silica), respectively. Tests of TOFA-silica particles have demonstrated...

  9. Bioremediation of uranium contamination with enzymatic uranium reduction

    Science.gov (United States)

    Lovley, D.R.; Phillips, E.J.P.

    1992-01-01

    Enzymatic uranium reduction by Desulfovibrio desulfuricans readily removed uranium from solution in a batch system or when D. desulfuricans was separated from the bulk of the uranium-containing water by a semipermeable membrane. Uranium reduction continued at concentrations as high as 24 mM. Of a variety of potentially inhibiting anions and metals evaluated, only high concentrations of copper inhibited uranium reduction. Freeze-dried cells, stored aerobically, reduced uranium as fast as fresh cells. D. desulfuricans reduced uranium in pH 4 and pH 7.4 mine drainage waters and in uraniumcontaining groundwaters from a contaminated Department of Energy site. Enzymatic uranium reduction has several potential advantages over other bioprocessing techniques for uranium removal, the most important of which are as follows: the ability to precipitate uranium that is in the form of a uranyl carbonate complex; high capacity for uranium removal per cell; the formation of a compact, relatively pure, uranium precipitate.

  10. Quantifying the limits of transition state theory in enzymatic catalysis.

    Science.gov (United States)

    Zinovjev, Kirill; Tuñón, Iñaki

    2017-11-21

    While being one of the most popular reaction rate theories, the applicability of transition state theory to the study of enzymatic reactions has been often challenged. The complex dynamic nature of the protein environment raised the question about the validity of the nonrecrossing hypothesis, a cornerstone in this theory. We present a computational strategy to quantify the error associated to transition state theory from the number of recrossings observed at the equicommittor, which is the best possible dividing surface. Application of a direct multidimensional transition state optimization to the hydride transfer step in human dihydrofolate reductase shows that both the participation of the protein degrees of freedom in the reaction coordinate and the error associated to the nonrecrossing hypothesis are small. Thus, the use of transition state theory, even with simplified reaction coordinates, provides a good theoretical framework for the study of enzymatic catalysis. Copyright © 2017 the Author(s). Published by PNAS.

  11. Physiological and enzymatic analyses of pineapple subjected to ionizing radiation

    International Nuclear Information System (INIS)

    Silva, Josenilda Maria da; Silva, Juliana Pizarro; Spoto, Marta Helena Fillet

    2007-01-01

    The physiological and enzymatic post-harvest characteristics of the pineapple cultivar Smooth Cayenne were evaluated after the fruits were gamma-irradiated with doses of 100 and 150 Gy and the fruits were stored for 10, 20 and 30 days at 12 deg C (±1) and relative humidity of 85% (±5). Physiological and enzymatic analyses were made for each storage period to evaluate the alterations resulting from the application of ionizing radiation. Control specimens showed higher values of soluble pectins, total pectins, reducing sugars, sucrose and total sugars and lower values of polyphenyloxidase and polygalacturonase enzyme activities. All the analyses indicated that storage time is a significantly influencing factor. The 100 Gy dosage and 20-day storage period presented the best results from the standpoint of maturation and conservation of the fruits quality. (author)

  12. Enzymatic transesterification of lipids from microalgae into biodiesel: a review

    Directory of Open Access Journals (Sweden)

    Maria del Pilar Rodriguez

    2016-10-01

    Full Text Available Biodiesel is considered as a potential interesting alternative diesel substitute due to its many advantages, such as biodegradability and non-toxicity. Biodiesel production worldwide is low and does not meet the needs of society. Therefore, biodiesel production policies have been implemented by various countries. This paper addresses the issues of plant materials containing lipids for biodiesel production and explores also the avenue of microalgae as an alternative. Various conversion technologies of lipids into biodiesel are also described and compared. Enzymatic transesterification would be most appropriate when microalgae oils are used because of their high free fatty acids content. The optimization of the enzymatic process depends on several parameters such as the catalyst, temperature, reaction time and the alcohol: oil molar ratio.

  13. From Fed-batch to Continuous Enzymatic Biodiesel Production

    DEFF Research Database (Denmark)

    Price, Jason Anthony; Nordblad, Mathias; Woodley, John M.

    2015-01-01

    In this this paper, we use mechanistic modelling to guide the development of acontinuous enzymatic process that is performed as a fed-batch operation. In this workwe use the enzymatic biodiesel process as a case study. A mechanistic model developedin our previous work was used to determine...... measured components (triglycerides, diglycerides, monoglycerides, free fatty acid and fatty acid methyl esters(biodiesel)) much better than using fed-batch data alone given the smaller residuals. We also observe a reduction in the correlation between the parameters.The model was then used to predict that 5...... reactors are required (with a combined residence time of 30 hours) to reach a final biodiesel concentration within 2 % of the95.6 mass % achieved in a fed-batch operation, for 24 hours....

  14. Novel investigation of enzymatic biodiesel reaction by isothermal calorimetry

    DEFF Research Database (Denmark)

    Søtoft, Lene Fjerbaek; Westh, Peter; Christensen, Knud V.

    2010-01-01

    Isothermal calorimetry (ITC) was used to investigate solvent-free enzymatic biodiesel production. The transesterification of rapeseed oil with methanol and ethanol was catalyzed by immobilized lipase Novozym 435 at 40 °C. The aim of the study was to determine reaction enthalpy for the enzymatic...... transesterification and to elucidate the mass transfer and energetic processes taking place. Based on the measured enthalpy and composition change in the system, the heat of reaction at 40 °C for the two systems was determined as −9.8 ± 0.9 kJ/mole biodiesel formed from rapeseed oil and methanol, and −9.3 ± 0.7 k...

  15. Enhanced enzymatic cellulose degradation by cellobiohydrolases via product removal

    DEFF Research Database (Denmark)

    Ahmadi Gavlighi, Hassan; Meyer, Anne S.; Mikkelsen, Jørn Dalgaard

    2013-01-01

    Product inhibition by cellobiose decreases the rate of enzymatic cellulose degradation. The optimal reaction conditions for two Emericella (Aspergillus) nidulans-derived cellobiohydrolases I and II produced in Pichia pastoris were identified as CBHI: 52 °C, pH 4.5–6.5, and CBHII: 46 °C, pH 4.......8. The optimum in a mixture of the two was 50 °C, pH 4.9. An almost fourfold increase in enzymatic hydrolysis yield was achieved with intermittent product removal of cellobiose with membrane filtration (2 kDa cut-off): The conversion of cotton cellulose after 72 h was ~19 % by weight, whereas the conversion...... achievable by intermittent product removal during cellulose hydrolysis....

  16. Rational design of functional and tunable oscillating enzymatic networks

    Science.gov (United States)

    Semenov, Sergey N.; Wong, Albert S. Y.; van der Made, R. Martijn; Postma, Sjoerd G. J.; Groen, Joost; van Roekel, Hendrik W. H.; de Greef, Tom F. A.; Huck, Wilhelm T. S.

    2015-02-01

    Life is sustained by complex systems operating far from equilibrium and consisting of a multitude of enzymatic reaction networks. The operating principles of biology's regulatory networks are known, but the in vitro assembly of out-of-equilibrium enzymatic reaction networks has proved challenging, limiting the development of synthetic systems showing autonomous behaviour. Here, we present a strategy for the rational design of programmable functional reaction networks that exhibit dynamic behaviour. We demonstrate that a network built around autoactivation and delayed negative feedback of the enzyme trypsin is capable of producing sustained oscillating concentrations of active trypsin for over 65 h. Other functions, such as amplification, analog-to-digital conversion and periodic control over equilibrium systems, are obtained by linking multiple network modules in microfluidic flow reactors. The methodology developed here provides a general framework to construct dissipative, tunable and robust (bio)chemical reaction networks.

  17. Parameters optimization for enzymatic assays using experimental design

    Directory of Open Access Journals (Sweden)

    J. F. M. Burkert

    2006-06-01

    Full Text Available The conditions for maximization enzymatic activity were determined using experimental design and inulinase from Kluyveromyces marxianus ATCC 16045. The effects of substrate concentration (sucrose and inulin, pH and temperature on inulinase activity were verified using four factorial design and surface response analysis. Using sucrose as substrate. It has bean shown that the effects sucrose on enzymatic activity is not statistically significant and the best condition for the highest activity (110 U/mL was achieved with temperature between 60°C and 68°C and pH between 4.5 and 5.0. Using inulin as substrate it was verified that temperature is the only variable statistically significant and the maximum activity was 7.3 U/mL at temperature between 50°C and 51°C.

  18. Electrochemical Detection of Mn(II and Cd(II Mediated by Carbon Nanotubes and Carbon Nanotubes/Li+ Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Muhammed M. Radhi

    2010-11-01

    Full Text Available Glassy carbon electrode (GCE was modified with carbon nanotubes (CNT with and without a Li+ dopant by using a mechanical attachment method; CNT/Li+/GCE was used as two working electrodes, by doping CNT/GCE with Li+. The nano-structure of the electrodes showed individual voltammetrics of Mn2+ with two reduction peaks at +800 and +100 mV. Two reduction peaks for Cd2+ appeared at +600 V and -800 mV with one oxidation peak at -600 mV. The reduction current of Mn2+ and the redox current of Cd2+ on the CNT/Li+/GCE were largely influenced by a low concentration comparison with GCE and CNT/GCE. It showed that the detection of Mn2+ and Cd2+ by CNT/Li+/GCE in an aqueous solution of 0.1M KCL, with a relative standard deviation (RSD of the electrode being very good CNT/Li+/GCE. The determination of efficiency for the best modified electrode was detected for Mn2+ and Cd2+ on CNT/Li+/GCE; it was also found to have a wide linear range and good repeatability with a relative standard deviation (RSD of ±1.9 % when this electrode was used and the limit of detection was found to be 10-4 to 10-3 mM of Mn2+ and 10-4 to 10-2 mM of Cd2+, while the range of detection was found to be 3x10-4 to 10-3 mM and 10-3 to 10 -2 mM when using the CNT/GCE for Mn2+and Cd2+, respectively, with an RSD of ±3.3 % for Mn2+ and Cd2+.

  19. Derivatization-free gel permeation chromatography elucidates enzymatic cellulose hydrolysis

    Directory of Open Access Journals (Sweden)

    Engel Philip

    2012-10-01

    Full Text Available Abstract Background The analysis of cellulose molecular weight distributions by gel permeation chromatography (GPC is a powerful tool to obtain detailed information on enzymatic cellulose hydrolysis, supporting the development of economically viable biorefinery processes. Unfortunately, due to work and time consuming sample preparation, the measurement of cellulose molecular weight distributions has a limited applicability until now. Results In this work we present a new method to analyze cellulose molecular weight distributions that does not require any prior cellulose swelling, activation, or derivatization. The cellulose samples were directly dissolved in dimethylformamide (DMF containing 10-20% (v/v 1-ethyl-3-methylimidazolium acetate (EMIM Ac for 60 minutes, thereby reducing the sample preparation time from several days to a few hours. The samples were filtrated 0.2 μm to avoid column blocking, separated at 0.5 mL/min using hydrophilic separation media and were detected using differential refractive index/multi angle laser light scattering (dRI/MALLS. The applicability of this method was evaluated for the three cellulose types Avicel, α-cellulose and Sigmacell. Afterwards, this method was used to measure the changes in molecular weight distributions during the enzymatic hydrolysis of the different untreated and ionic liquid pretreated cellulose substrates. The molecular weight distributions showed a stronger shift to smaller molecular weights during enzymatic hydrolysis using a commercial cellulase preparation for cellulose with lower crystallinity. This was even more pronounced for ionic liquid-pretreated cellulose. Conclusions In conclusion, this strongly simplified GPC method for cellulose molecular weight distribution allowed for the first time to demonstrate the influence of cellulose properties and pretreatment on the mode of enzymatic hydrolysis.

  20. Novel flavonolignan hybrid antioxidants: From enzymatic preparation to molecular rationalization

    Czech Academy of Sciences Publication Activity Database

    Vavříková, Eva; Křen, Vladimír; Ježová-Kalachová, Lubica; Biler, M.; Chantemargue, B.; Pyszková, M.; Riva, S.; Kuzma, Marek; Valentová, Kateřina; Ulrichová, J.; Vrba, J.; Trouillas, P.; Vacek, J.

    2017-01-01

    Roč. 127, FEB 15 (2017), s. 263-274 ISSN 0223-5234 R&D Projects: GA MŠk(CZ) LD14096; GA MŠk(CZ) LD15084; GA ČR(CZ) GA15-03037S Institutional support: RVO:61388971 Keywords : Silybin * Vitamin C * Enzymatic coupling Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 4.519, year: 2016

  1. Biodiesel production by chemical or enzymatic esterification of sunflower oil

    Energy Technology Data Exchange (ETDEWEB)

    Passarinho, Paula C.; Rosa, M. Fernanda; Oliveira, A.C.; Pingarilho, M.S.; Beirao, S.G.; Vieira, Ana Maria Soares

    1998-07-01

    In this work, two processes of sunflower oil transesterification, with methanol or ethanol, were studied for biodiesel production: chemical (catalyst- NaOH) and enzymatic (catalyst - rhizomucor miehei lipase). The chemical catalysis proved to be more efficient, having been obtained higher conversion yields and a better quality biodiesel, mainly in the case where methanol was used. The transesterification product had, in all cases, to be purified in order to be used as a diesel substitute.

  2. Enzymatic determination of rare earth elements using pyrophosphatases

    International Nuclear Information System (INIS)

    Shekhovtsova, T.N.; Pirogova, S.V.; Fedorova, O.M.; Dolmanova, I.F.; Bajkov, A.A.

    1993-01-01

    A highly sensitive(determination limit 8x10 -6 -4x10 -4 μ g/m) and selective enzymatic method for determination of rare earth elements has been developed. The method is based on inhibition action of rare earths on the catalytic activity of pyrophosphates isolated from bakery geast and E.Coli. The mechanism of the rare earth element action, corresponding to competitive inhibition, has been established

  3. Enzymatic determination of rare earth elements by use of pyrophosphotases

    International Nuclear Information System (INIS)

    Shekhovtseva, T.N.; Pirogova, S.V.; Fedorova, O.M.; Dolmanova, I.F.; Bajkov, A.A.

    1993-01-01

    A highly sensitive (determination limit 8 x 10 -6 - 4 x 10 -4 μg/ml) and selective enzymatic method for determination of rare earth elements has been developed. The method is based on inhibition action of rare earths on the catalytic activity of pyrophosphates isolated from bakery geast and E. Coli. The mechanism of the rare earth element action, corresponding to competitive inhibition, has been established

  4. Global Warming Potential Of A Waste Refinery Using Enzymatic Treatment

    DEFF Research Database (Denmark)

    Tonini, Davide; Astrup, Thomas

    2010-01-01

    and fossil resources. This is especially important with respect to the residual waste (i.e. the remains after source-separation and separate collection) which is typically incinerated or landfilled. In this paper the energy and Global Warming performance of a pilot-scale waste refinery for the enzymatic...... plants and utilization of the liquid fraction for biogas production turned out to be the best options with respect to energy and Global Warming performance....

  5. Physiological and enzymatic alterations in papaya seed during storage

    OpenAIRE

    Dias, Denise Cunha Fernandes Dos Santos; Estanislau, Wagner Tompson; Finger, Fernando Luiz; Alvarenga, Eveline Mantovani; Dias, Luiz Antônio Dos Santos

    2010-01-01

    This study was done to evaluate the physiological and enzymatic alterations in papaya (Carica papaya L.) seeds during storage period. Seeds were extracted from mature fruits of Formosa group papaya hybrid Tainung 01. The sarcotesta was removed by rubbing the seeds on a wire screen under running water and then dried to the moisture content (MC) of 5, 8 or 11% The seeds were packed in multilayer paper bags, polyethylene bags, aluminum foil pouch and metallic canisters and stored for 15 months u...

  6. Optimization of enzymatic hydrolysis of skipjack tuna by-product ...

    African Journals Online (AJOL)

    The goal of this study was to optimize enzymatic hydrolysis of the dark flesh of skipjack tuna (Katsuwonus pelamis). Protamex® was used as the hydrolytic enzyme at various concentrations (1%, 1.5%, 2%, 2.5% and 3% w/w) at pHs from 6.5 to 8.5, temperatures from 40 to 60 oC and times of 2 to 6 h. The experiment was ...

  7. ASPECTS CONCERNING THE ENZYMATIC ACTIVITY IN SEVERAL THERMOACTINOMYCETE STRAINS

    Directory of Open Access Journals (Sweden)

    Simona Dunca

    2003-08-01

    Full Text Available In the thermoactinomycete strains subjected to examination the values of their recorded enzymatic activities (i.e. α-amy lase, protease, exo-β-1,4 – glucanase, endo -β-1,4 – glucanase and β-glucosidase were lower in the stationary cultures as compared to the stirred ones. The strain Thermomonospora fusca BB255 was found to be highly cellulase- producing and at the same time able to synthesize α-amy lases and proteases.

  8. CO(2) fixation through hydrogenation by chemical or enzymatic methods.

    Science.gov (United States)

    Beller, Matthias; Bornscheuer, Uwe T

    2014-04-25

    Two birds with one stone: The simulaneous fixation of the greenhouse gas carbon dioxide and storage of the alternative fuel hydrogen can be accomplished with the formation of formic acid. In principle, this is now possible either with an enzymatic system based on a newly discovered bacterial hydrogen-dependent carbon dioxide reductase or by using organometallic catalysts at room temperature and ambient pressure. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Nanosilver: A Catalyst in Enzymatic Hydrolysis of Starch

    Directory of Open Access Journals (Sweden)

    Falkowska Marta

    2014-09-01

    Full Text Available Silver nanoparticles are widely used, because of their antimicrobial properties. In this paper, the rate of starch digestion in the presence of nanocatalyst was compared with the rate of reaction without nanosilver. The rate of enzymatic degradation of starch was found to be increased in the presence of silver nanoparticles. It is considered that α-amylase was immobilized onto the surface of nanoparticles.

  10. Bioethanol production: Pretreatment and enzymatic hydrolysis of softwood

    Energy Technology Data Exchange (ETDEWEB)

    Tengborg, Charlotte

    2000-05-01

    The enzymatic hydrolysis process can be used to produce bioethanol from softwood, which are the dominating raw material in the Northern hemisphere. This thesis deals with the development of the process focusing on the pretreatment and the enzymatic hydrolysis stages. The influence of pretreatment conditions on sugar yield, and the effect of inhibitors on the ethanol yield, were investigated for spruce and pine. The maximum yields of hemicellulose sugars and glucose were obtained under different pretreatment conditions. This indicates that two-stage pretreatment may be preferable. The added catalysts, H{sub 2}SO{sub 4} and SO{sub 2}, resulted in similar total sugar yields about 40 g/100 g dry raw material. However, the fermentability of SO{sub 2}-impregnated material was better. This pretreatment resulted in the formation of inhibitors to the subsequent process steps, e.g. sugar and lignin degradation products. The glucose yield in the enzymatic hydrolysis stage was affected by various parameters such as enzyme loading, temperature, pH, residence time, substrate concentration, and agitation. To decrease the amount of fresh water used and thereby waste water produced, the sugar-rich prehydrolysate from the pretreatment step was included in the enzymatic hydrolysis of the solid fraction, resulting in a reduction in the cellulose conversion of up to 36%. Different prehydrolysate detoxification methods, such as treatment with Ca(OH){sub 2}, laccase, and fermentation using yeast, were investigated. The latter was shown to be very efficient. The amount of fresh water used can be further reduced by recycling various process streams. This was simulated experimentally in a bench-scale process. A reduction in fresh water demand of 50% was obtained without any further negative effects on either hydrolysis or fermentation.

  11. Enzymatic analysis of venom from Cuban scorpion Rhopalurus junceus

    OpenAIRE

    D?az-Garc?a, Alexis; Ruiz-Fuentes, Jenny Laura; Yglesias-Rivera, Arianna; Rodr?guez-S?nchez, Hermis; Riquenes Garlobo, Yanelis; Fleitas Martinez, Osmel; Fraga Castro, Jos? A

    2015-01-01

    Rhopalurus junceus scorpion venom has been identified as a natural extract with anticancer potential. Interestingly, this scorpion venom does not cause adverse symptoms in humans. However, there is scarce information about its composition and enzymatic activity. In this work, we determined the electrophoretic profile of the venom, the gelatinase and caseinolytic activity, and the phospholipase A2 (PLA2) and hemolytic activity. The effect of different venom doses (6.25, 12.5 and 25 mg/kg) on g...

  12. The integrated enzymatic production and downstream processing of glucosides

    OpenAIRE

    Roode, de, B.M.

    2001-01-01

    Glucosides are of commercial interest for the industry in general and for the pharmaceutical and food industry in particular. Chemical preparation of glycosides is not applicable in the food industry, and therefore an enzyme-catalyzed reaction would be an alternative. However, until now the low yield in the enzymatic reaction prevents the production of glycosides on a commercial scale. Therefore, high yields should be established by a combination of optimum reaction conditions and a ...

  13. Tetradentate Schiff base ligands and their complexes: Synthesis, structural characterization, thermal, electrochemical and alkane oxidation

    Science.gov (United States)

    Ceyhan, Gökhan; Köse, Muhammet; McKee, Vickie; Uruş, Serhan; Gölcü, Ayşegül; Tümer, Mehmet

    Three Schiff base ligands (H2L1-H2L3) with N2O2 donor sites were synthesized by condensation of 1,5-diaminonapthalene with benzaldehyde derivatives. A series of Cu(II), Co(II), Ni(II), Mn(II) and Cr(III) complexes were prepared and characterized by spectroscopic and analytical methods. Thermal, electrochemical and alkane oxidation reactions of the ligands and their metal complexes were investigated. Extensive application of 1D (1H, 13C NMR) and 2D (COSY, HETCOR, HMBC and TOSCY) NMR techniques were used to characterize the structures of the ligands and establish the 1H and 13C resonance assignments of the three ligands. Ligands H2L1 and H2L3 were obtained as single crystals from THF solution and characterized by X-ray diffraction. Both molecules are centrosymmetric and asymmetric unit contains one half of the molecule. Catalytic alkane oxidation reactions with the transition metal complexes investigated using cyclohexane and cyclooctane as substrates. The Cu(II) and Cr(III) complexes showed good catalytic activity in the oxidation of cyclohexane and cyclooctane to desired oxidized products. Electrochemical and thermal properties of the compounds were also investigated.

  14. Enzymatic degradation behavior and cytocompatibility of silk fibroin-starch-chitosan conjugate membranes

    Energy Technology Data Exchange (ETDEWEB)

    Baran, Erkan T., E-mail: erkantur@metu.edu.tr; Tuzlakoglu, Kadriye, E-mail: kadriye@dep.uminho.pt; Mano, Joao F., E-mail: jmano@dep.uminho.pt; Reis, Rui L., E-mail: rgreis@dep.uminho.pt

    2012-08-01

    The objective of this study was to investigate the influence of silk fibroin and oxidized starch conjugation on the enzymatic degradation behavior and the cytocompatability of chitosan based biomaterials. The tensile stress of conjugate membranes, which was at 50 Megapascal (MPa) for the lowest fibroin and starch composition (10 weight percent (wt.%)), was decreased significantly with the increased content of fibroin and starch. The weight loss of conjugates in {alpha}-amylase was more notable when the starch concentration was the highest at 30 wt.%. The conjugates were resistant to the degradation by protease and lysozyme except for the conjugates with the lowest starch concentration. After 10 days of cell culture, the proliferation of osteoblast-like cells (SaOS-2) was stimulated significantly by higher fibroin compositions and the DNA synthesis on the conjugate with the highest fibroin (30 wt.%) was about two times more compared to the native chitosan. The light microscopy and the image analysis results showed that the cell area and the lengths were decreased significantly with higher fibroin/chitosan ratio. The study proved that the conjugation of fibroin and starch with the chitosan based biomaterials by the use of non-toxic reductive alkylation crosslinking significantly improved the cytocompatibility and modulated the biodegradation, respectively. - Highlights: Black-Right-Pointing-Pointer Silk fibroin, starch and chitosan conjugates were prepared by reductive alkylation. Black-Right-Pointing-Pointer The enzymatic biodegradation and the cytocompatibility of conjugates were tested. Black-Right-Pointing-Pointer The conjugate with 30% starch composition was degraded by {alpha}-amylase significantly. Black-Right-Pointing-Pointer Higher starch composition in conjugates prevented protease and lysozyme degradation. Black-Right-Pointing-Pointer Fibroin incorporation effectively increased the cell proliferation of conjugates.

  15. Microstructural study of pre-treated and enzymatic hydrolyzed bamboo

    Directory of Open Access Journals (Sweden)

    Funsho O. KOLAWOLE

    2016-07-01

    Full Text Available Bamboo was used as biomass feedstock which was pre-treated using dilute acid hydrolysis followed by enzymatic hydrolysis. The bamboo was mechanical ground to particle sizes 212–500µm, followed by pre-treatment with dilute sulfuric acid at a concentration of 0.5 and 1.0 (%v/v at temperatures of 25, 110, 120, 150 and 200°C with time intervals of 2 and 4 hours. Pre-hydrolyzate was later analyzed for reducing sugar using UV-Vis spectrophotometry. Under the above conditions, a maximum glucose yield of 153.1 mg/g was obtained at 200°C and acid concentrations of 1% for 4 hours. Water insoluble solids obtained were subsequently hydrolyzed with Celluclast (Trichoderma reesi and β-glucosidase (Novozyme 188 for 72 hours. Optical Microscope and ESEM images of bamboo samples were obtained at various stages of pre-treatment and enzymatic hydrolysis. Result reveals a breakdown in the ligno-cellulosic structure of the bamboo during exposure to dilute acid and enzymatic hydrolysis.

  16. Thermodynamic feasibility of enzymatic reduction of carbon dioxide to methanol.

    Science.gov (United States)

    Baskaya, F Suhan; Zhao, Xueyan; Flickinger, Michael C; Wang, Ping

    2010-09-01

    Production of valuable chemicals from CO(2) is highly desired for the purpose of controlling CO(2) emission. Toward that, enzymatic reduction of CO(2) for the production of methanol appeared to be especially promising. That has been achieved by reversing the biological metabolic reaction pathways. However, hitherto, there has been little discussion on the thermodynamic feasibility of reversing such biological pathways. The reported yields of methanol have been generally very low under regular reaction conditions preferred by naturally evolved enzymes. The current work examines the sequential enzymatic conversion of CO(2) into methanol from a thermodynamic point of view with a focus on factors that control the reaction equilibrium. Our analysis showed that the enzymatic conversion of carbon dioxide is highly sensitive to the pH value of the reaction solution and, by conducting the reactions at low pHs (such as pH 6 or 5) and ionic strength, it is possible to shift the biological methanol metabolic reaction equilibrium constants significantly (by a factor of several orders of magnitude) to favor the synthesis of methanol.

  17. Oxidative atom-transfer to a trimanganese complex to form Mn6(μ6-E) (E = O, N) clusters featuring interstitial oxide and nitride functionalities.

    Science.gov (United States)

    Fout, Alison R; Zhao, Qinliang; Xiao, Dianne J; Betley, Theodore A

    2011-10-26

    Utilizing a hexadentate ligand platform, a trinuclear manganese complex of the type ((H)L)Mn(3)(thf)(3) was synthesized and characterized ([(H)L](6-) = [MeC(CH(2)N(C(6)H(4)-o-NH))(3)](6-)). The pale-orange, formally divalent trimanganese complex rapidly reacts with O-atom transfer reagents to afford the μ(6)-oxo complex ((H)L)(2)Mn(6)(μ(6)-O)(NCMe)(4), where two trinuclear subunits bind the central O-atom and the ((H)L) ligands cooperatively bind both trinuclear subunits. The trimanganese complex ((H)L)Mn(3)(thf)(3) rapidly consumes inorganic azide ([N(3)]NBu(4)) to afford a dianionic hexanuclear nitride complex [((H)L)(2)Mn(6)(μ(6)-N)](NBu(4))(2), which subsequently can be oxidized with elemental iodine to ((H)L)(2)Mn(6)(μ(6)-N)(NCMe)(4). EPR and alkylation of the interstitial light atom substituent were used to distinguish the nitride from the oxo complex. The oxo and oxidized nitride complexes give rise to well-defined Mn(II) and Mn(III) sites, determined by bond valence summation, while the dianionic nitride shows a more symmetric complex, giving rise to indistinguishable ion oxidation states based on crystal structure bond metrics.

  18. Catalytic metal ions and enzymatic processing of DNA and RNA.

    Science.gov (United States)

    Palermo, Giulia; Cavalli, Andrea; Klein, Michael L; Alfonso-Prieto, Mercedes; Dal Peraro, Matteo; De Vivo, Marco

    2015-02-17

    CONSPECTUS: Two-metal-ion-dependent nucleases cleave the phosphodiester bonds of nucleic acids via the two-metal-ion (2M) mechanism. Several high-resolution X-ray structures portraying the two-metal-aided catalytic site, together with mutagenesis and kinetics studies, have demonstrated a functional role of the ions for catalysis in numerous metallonucleases. Overall, the experimental data confirm the general mechanistic hypothesis for 2M-aided phosphoryl transfer originally reported by Steitz and Steitz ( Proc. Natl. Acad. Sci. U.S.A. 1993 , 90 ( 14 ), 6498 - 6502 ). This seminal paper proposed that one metal ion favors the formation of the nucleophile, while the nearby second metal ion facilitates leaving group departure during RNA hydrolysis. Both metals were suggested to stabilize the enzymatic transition state. Nevertheless, static X-ray structures alone cannot exhaustively unravel how the two ions execute their functional role along the enzymatic reaction during processing of DNA or RNA strands when moving from reactants to products, passing through metastable intermediates and high-energy transition states. In this Account, we discuss the role of multiscale molecular simulations in further disclosing mechanistic insights of 2M-aided catalysis for two prototypical enzymatic targets for drug discovery, namely, ribonuclease H (RNase H) and type II topoisomerase (topoII). In both examples, first-principles molecular simulations, integrated with structural data, emphasize a cooperative motion of the bimetal motif during catalysis. The coordinated motion of both ions is crucial for maintaining a flexible metal-centered structural architecture exquisitely tailored to accommodate the DNA or RNA sugar-phosphate backbone during phosphodiester bond cleavage. Furthermore, our analysis of RNase H and the N-terminal domain (PAN) of influenza polymerase shows that classical molecular dynamics simulations coupled with enhanced sampling techniques have contributed to describe

  19. Evaluation of ecotoxicological effects of drugs on Daphnia magna using different enzymatic biomarkers.

    Science.gov (United States)

    Oliveira, Laira L D; Antunes, Sara C; Gonçalves, Fernando; Rocha, Odete; Nunes, Bruno

    2015-09-01

    The increasing occurrence of pharmaceutical drugs in the aquatic environment is cause of concern, due to the possibility of toxic phenomena in non-target species, including oxidative stress and neurotoxicity. The present study aimed to assess the acute effect of four widely used therapeutic agents: acetaminophen (analgesic), chlorpromazine (antipsychotic), diclofenac (anti-inflammatory) and propranolol (antihypertensive), in the cladoceran species Daphnia magna. Considering the involvement of the mentioned compounds in the impairment of cholinesterasic activity and modifications in cellular redox systems, the purpose of this study was to analyze their effects on biomarkers of neuronal regulation, such as total cholinesterases (ChEs), and enzymatic oxidative stress defense, including as catalase (CAT), glutathione-S-transferases (GSTs), and total and selenium-dependent glutathione-peroxidase (total GPx; Se-GPx) activities. Exposure to acetaminophen caused a significant inhibition of AChE and Se-GPx activities in D. magna relative to the control. Among the biomarkers of oxidative stress, only the activity of CAT was significantly altered in concentration of 0.001mg L(-1) of chlorpromazine, which was not always consistent with the literature. Diclofenac caused a significant inhibition of AChE and Se-dependent GPx, and also in total GPx activities. Propranolol was responsible for a significant decrease in the activity of the latter two enzymes, and also a slight increase of GSTs activity. The results indicated that the exposure to all the tested compounds induced alterations on the cellular redox status in the studied species. In addition, acetaminophen and diclofenac were shown to have the capability of interfering with D. magna neurotransmission, through the inhibition of ChEs. Our data enlighten the need for more research on the ecological consequences of pharmaceuticals in non-target organisms. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. A green synthetic strategy of nickel hexacyanoferrate nanoparticals supported on the graphene substrate and its non-enzymatic amperometric sensing application

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhonghua, E-mail: xzh@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); He, Nan [Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Rao, Honghong [College of Chemistry and Chemical Engineering, Lanzhou City University, Lanzhou, 730070 (China); Hu, Chenxian; Wang, Xiaofen; Wang, Hui; Liu, Xiuhui [Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Lu, Xiaoquan, E-mail: luxq@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2017-02-28

    Highlights: • A sensitive non-enzymatic glucose sensor was explored by using a facile and green strategy. • Well dispersed and uniform NiHCF nanoparticles can be effectively produced by the introduction of electrochemical reduction graphene oxide films. • Metal hexacyanoferrate as a potential electron mediator was proposed and applied into non-enzymatic sensing. - Abstract: Rapid glucose detection is a key requirement for both diagnosis and treatment of diabetes. A facile and green strategy to achieve spherical-shaped nickel hexacyanoferrate (NiHCF) nanoparticals supported on electrochemical reduction graphene oxide by using electrochemical cyclic voltammetry is explored. As a sensing substrate, electrochemical reduction graphene oxide deposited on a glassy carbon electrode surface exhibited obvious positive effect on the electrodeposition of NiHCF nanoparticals with spherical structure and thus effectively improved the electrical conductivity and electrochemical sensing of the proposed amperometric sensor. Proof-concept experiments demonstrated that the proposed nanocomposites modified electrode exhibited excellent sensitivity toward glucose oxidation as well as with a satisfying detection limit of 0.11 μM. More importantly, we also explore that as a simple, green and facile method, electrochemical technology can be employed and provide a new strategy for developing GO and metal hexacyanoferrate based amperometric sensing platform toward glucose and other biomolecules.

  1. A green synthetic strategy of nickel hexacyanoferrate nanoparticals supported on the graphene substrate and its non-enzymatic amperometric sensing application

    International Nuclear Information System (INIS)

    Xue, Zhonghua; He, Nan; Rao, Honghong; Hu, Chenxian; Wang, Xiaofen; Wang, Hui; Liu, Xiuhui; Lu, Xiaoquan

    2017-01-01

    Highlights: • A sensitive non-enzymatic glucose sensor was explored by using a facile and green strategy. • Well dispersed and uniform NiHCF nanoparticles can be effectively produced by the introduction of electrochemical reduction graphene oxide films. • Metal hexacyanoferrate as a potential electron mediator was proposed and applied into non-enzymatic sensing. - Abstract: Rapid glucose detection is a key requirement for both diagnosis and treatment of diabetes. A facile and green strategy to achieve spherical-shaped nickel hexacyanoferrate (NiHCF) nanoparticals supported on electrochemical reduction graphene oxide by using electrochemical cyclic voltammetry is explored. As a sensing substrate, electrochemical reduction graphene oxide deposited on a glassy carbon electrode surface exhibited obvious positive effect on the electrodeposition of NiHCF nanoparticals with spherical structure and thus effectively improved the electrical conductivity and electrochemical sensing of the proposed amperometric sensor. Proof-concept experiments demonstrated that the proposed nanocomposites modified electrode exhibited excellent sensitivity toward glucose oxidation as well as with a satisfying detection limit of 0.11 μM. More importantly, we also explore that as a simple, green and facile method, electrochemical technology can be employed and provide a new strategy for developing GO and metal hexacyanoferrate based amperometric sensing platform toward glucose and other biomolecules.

  2. Enzymatic conversion of CO2 to CH3OH via reverse dehydrogenase cascade biocatalysis: Quantitative comparison of efficiencies of immobilized enzyme systems

    DEFF Research Database (Denmark)

    Marpani, Fauziah Binti; Pinelo, Manuel; Meyer, Anne S.

    2017-01-01

    the reaction warrants innovative development. There is a particular need for development of i) better enzymes; ii) improved understanding of enzyme structure function aspects of reverse catalysis by dehydrogenases, iii) quantitative kinetic models of the enzymatic cascade reaction during simultaneous cofactor......A designed biocatalytic cascade system based on reverse enzymatic catalysis by formate dehydrogenase (EC 1.2.1.2), formaldehyde dehydrogenase (EC 1.2.1.46), and alcohol dehydrogenase (EC 1.1.1.1) can convert carbon dioxide (CO2) to methanol (CH3OH) via formation of formic acid (CHOOH......) and formaldehyde (CHOH) during equimolar cofactor oxidation of NADH to NAD+. This reaction is appealing because it represents a double gain: (1) reduction of CO2 and (2) an alternative to fossil fuel based production of CH3OH. The present review evaluates the efficiency of different immobilized enzyme systems...

  3. Enzymatic methods for choline-containing water soluble phospholipids based on fluorescence of choline oxidase: Application to lyso-PAF.

    Science.gov (United States)

    Sanz-Vicente, Isabel; Domínguez, Andrés; Ferrández, Carlos; Galbán, Javier

    2017-02-15

    In this paper we present methods to determine water soluble phospholipids containing choline (wCh-PL). The analytes were hydrolyzed by the enzyme phospholipase D and the choline formed was oxidized by the enzyme Choline Oxidase (ChOx); the fluorescence changes of the ChOx are followed during the enzymatic reaction, avoiding the necessity of an indicating step. Both reactions (hydrolysis and oxidation) can be combined in two different ways: 1) a two-step process (TSP) in which the hydrolysis reaction takes place during an incubation time and then the oxidation reaction is carried out, the analytical signal being provided by the intrinsic fluorescence of ChOx due to tryptophan; 2) a one-step process (OSP) in which both enzymatic reactions are carried out simultaneously in the same test; in this case the analytical signal is provided by the ChOx extrinsic fluorescence due to a fluorescent probe (Ru (II) chelate) linked to the enzyme (ChOx-RuC). The analytical capabilities of these methods were studied using 1,2-dioctanoyl-sn-glycero-3-phosphocholine (C 8 PC), a water soluble short alkyl chain Ch-PL as a substrate, and 1-O-hexadecyl-sn-glyceryl-3-phosphorylcholine (lyso-PAF). The analytical features of merit for both analytes using both methods were obtained. The TSP gave a 10-fold sensitivity and lower quantification limit (1.0*10 -5  M for lyso-PAF), but OSP reduced the determination time and permitted to use the same enzyme aliquot for several measurements. Both methods gave similar precision (RSD 7%, n = 5). The TSP was applied to the determination of C 8 PC and lyso-PAF in spiked synthetic serum matrix using the standard addition method. The application of this methodology to PLD activity determination is also discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Electrodeposition of flower-like platinum on electrophoretically grown nitrogen-doped graphene as a highly sensitive electrochemical non-enzymatic biosensor for hydrogen peroxide detection

    Energy Technology Data Exchange (ETDEWEB)

    Tajabadi, M.T. [University Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Sookhakian, M., E-mail: m.sokhakian@gmail.com [University Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Korea (Korea, Republic of); Zalnezhad, E., E-mail: erfan@hanyang.ac.kr [Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Korea (Korea, Republic of); Yoon, G.H. [Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Korea (Korea, Republic of); Hamouda, A.M.S. [Mechanical and Industrial Engineering Department, College of Engineering, Qatar University, 2713, Doha (Qatar); Azarang, Majid [Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Basirun, W.J. [Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Institute of Nanotechnology & Catalysis Research, Institute of Postgraduate Studies, University Malaya, 50603 Kuala Lumpur (Malaysia); Alias, Y., E-mail: yatimah70@um.edu.my [University Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia)

    2016-11-15

    Highlights: • Nitrogen doped graphene with different thickness by electrophoretic deposition. • The conductivity of N-graphene layer depends on the tickness. • Support of platinum shows efficient electrocatalytic performance for biosensor. • CV curves and amperometric responses improved and optimized in the presence of N-graphene. - Abstract: An efficient non-enzymatic biosensor electrode consisting of nitrogen-doped graphene (N-graphene) and platinum nanoflower (Pt NF) with different N-graphene loadings were fabricated on indium tin oxide (ITO) glass using a simple layer-by-layer electrophoretic and electrochemical sequential deposition approach. N-graphene was synthesized by annealing graphene oxide with urea at 900 °C. The structure and morphology of the as-fabricated non-enzymatic biosensor electrodes were determined using X-ray diffraction, field emission electron microscopy, transmission electron microscopy, Raman and X-ray photoelectron spectra. The as-fabricated Pt NF-N-graphene-modified ITO electrodes with different N-graphene loadings were utilized as a non-enzymatic biosensor electrode for the detection of hydrogen peroxide (H{sub 2}O{sub 2}). The behaviors of the hybrid electrodes towards H{sub 2}O{sub 2} reduction were assessed using chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy analysis. The Pt NF-N-graphene-modified ITO electrode with a 0.05 mg ml{sup −1} N-graphene loading exhibited the lowest detection limit, fastest amperometric sensing, a wide linear response range, excellent stability and reproducibility for the non-enzymatic H{sub 2}O{sub 2} detection, due to the synergistic effect between the electrocatalytic activity of the Pt NF and the high conductivity and large surface area of N-graphene.

  5. Protective effects against H2O2-induced damage by enzymatic hydrolysates of an edible brown seaweed, sea tangle (Laminaria japonica).

    Science.gov (United States)

    Park, Pyo-Jam; Kim, Eun-Kyung; Lee, Seung-Jae; Park, Sun-Young; Kang, Dong-Soo; Jung, Bok-Mi; Kim, Kui-Shik; Je, Jae-Young; Ahn, Chang-Bum

    2009-02-01

    Enzymatic hydrolysates of Laminaria japonica were evaluated for antioxidative activities using hydroxyl radical scavenging activity and protective effects against H(2)O(2)-induced DNA and cell damage. In addition, activities of antioxidative enzymes, including catalase, glutathione peroxidase, and glutathione S-transferase, of the enzymatic hydrolysates from L. japonica were also estimated. L. japonica was first enzymatically hydrolyzed by seven carbohydrases (Dextrozyme, AMG, Promozyme, Maltogenase, Termamyl, Viscozyme, and Celluclast [all from Novo Co., Novozyme Nordisk, Bagsvaerd, Denmark]) and five proteinases (Flavourzyme, Neutrase, Protamex, Alcalase [all from Novo Co.], and pancreatic trypsin). The hydroxyl radical scavenging activities of Promozyme and pancreatic trypsin hydrolysates from L. japonica were the highest as compared to those of the other carbohydrases and proteinases, and their 50% inhibitory concentration values were 1.67 and 317.49 mug/mL, respectively. The pancreatic trypsin hydrolysates of L. japonica exerted a protective effect on H(2)O(2)-induced DNA damage. We also evaluated the protective effect on hydroxyl radical-induced oxidative damage in PC12 cells via propidium iodide staining using a flow cytometer. The AMG and pancreatic trypsin hydrolysates of L. japonica dose-dependently protected PC12 cells against cell death caused by hydroxyl radical-induced oxidative damage. Additionally, we analyzed the activity of antioxidative enzymes such as catalase, glutathione peroxidase, and the phase II biotransformation enzyme glutathione S-transferase in L. japonica-treated cells. The activity of all antioxidative enzymes was higher in L. japonica-treated cells compared with the nontreated cells. These results indicate that enzymatic hydrolysates of L. japonica possess antioxidative activity.

  6. Electrodeposition of flower-like platinum on electrophoretically grown nitrogen-doped graphene as a highly sensitive electrochemical non-enzymatic biosensor for hydrogen peroxide detection

    International Nuclear Information System (INIS)

    Tajabadi, M.T.; Sookhakian, M.; Zalnezhad, E.; Yoon, G.H.; Hamouda, A.M.S.; Azarang, Majid; Basirun, W.J.; Alias, Y.

    2016-01-01

    Highlights: • Nitrogen doped graphene with different thickness by electrophoretic deposition. • The conductivity of N-graphene layer depends on the tickness. • Support of platinum shows efficient electrocatalytic performance for biosensor. • CV curves and amperometric responses improved and optimized in the presence of N-graphene. - Abstract: An efficient non-enzymatic biosensor electrode consisting of nitrogen-doped graphene (N-graphene) and platinum nanoflower (Pt NF) with different N-graphene loadings were fabricated on indium tin oxide (ITO) glass using a simple layer-by-layer electrophoretic and electrochemical sequential deposition approach. N-graphene was synthesized by annealing graphene oxide with urea at 900 °C. The structure and morphology of the as-fabricated non-enzymatic biosensor electrodes were determined using X-ray diffraction, field emission electron microscopy, transmission electron microscopy, Raman and X-ray photoelectron spectra. The as-fabricated Pt NF-N-graphene-modified ITO electrodes with different N-graphene loadings were utilized as a non-enzymatic biosensor electrode for the detection of hydrogen peroxide (H 2 O 2 ). The behaviors of the hybrid electrodes towards H 2 O 2 reduction were assessed using chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy analysis. The Pt NF-N-graphene-modified ITO electrode with a 0.05 mg ml −1 N-graphene loading exhibited the lowest detection limit, fastest amperometric sensing, a wide linear response range, excellent stability and reproducibility for the non-enzymatic H 2 O 2 detection, due to the synergistic effect between the electrocatalytic activity of the Pt NF and the high conductivity and large surface area of N-graphene.

  7. Increased Reactive Oxygen Species Formation and Oxidative Stress in Rheumatoid Arthritis.

    Directory of Open Access Journals (Sweden)

    Somaiya Mateen

    Full Text Available Rheumatoid arthritis (RA is an autoimmune inflammatory disorder. Highly reactive oxygen free radicals are believed to be involved in the pathogenesis of the disease. In this study, RA patients were sub-grouped depending upon the presence or absence of rheumatoid factor, disease activity score and disease duration. RA Patients (120 and healthy controls (53 were evaluated for the oxidant-antioxidant status by monitoring ROS production, biomarkers of lipid peroxidation, protein oxidation and DNA damage. The level of various enzymatic and non-enzymatic antioxidants was also monitored. Correlation analysis was also performed for analysing the association between ROS and various other parameters.Intracellular ROS formation, lipid peroxidation (MDA level, protein oxidation (carbonyl level and thiol level and DNA damage were detected in the blood of RA patients. Antioxidant status was evaluated by FRAP assay, DPPH reduction assay and enzymatic (SOD, catalase, GST, GR and non-enzymatic (vitamin C and GSH antioxidants.RA patients showed a higher ROS production, increased lipid peroxidation, protein oxidation and DNA damage. A significant decline in the ferric reducing ability, DPPH radical quenching ability and the levels of antioxidants has also been observed. Significant correlation has been found between ROS and various other parameters studied.RA patients showed a marked increase in ROS formation, lipid peroxidation, protein oxidation, DNA damage and decrease in the activity of antioxidant defence system leading to oxidative stress which may contribute to tissue damage and hence to the chronicity of the disease.

  8. [Enzymatic methods in the analysis of musts and wines].

    Science.gov (United States)

    Lafon-Lafourcade, S

    1978-01-01

    The enzymatic methods are based on the property of the enzymes to catalyse specifically and reversibly the conversion of certain metabolites. These methods, developed thanks to the industrial preparation of enzymes, can be applied with no major modification to the analysis of drinks. About 15 constituants of musts and wines can now be determined by these methods. If their cost price was not relatively high, their specificity, sensitivity and rapidity would enable them to compete with the most precise of chemical methods. This is why they are only used in analytic oenology when chemical analysis is most specific enough or too laborious. Enzymatic measurement allows one by its specificity to determine the amount of residual sugar that is fermentable in a dry wine and by its sensitivity to verifie the total disappearance of the malic acid of the wine. Its rapidity must make it preferable to the long and not very specific chemical measurement, especially concerning the determination of citric acid. But glycerol, ethanol and acetic acid can be measured by chemical or chromatographical means with sufficient precision and for a more modest price. In oenology the methods are essentially used for research. They have permitted the study of the combinations of sulphur anhydride in wines (measurement of cetonic acids). The determination of the isomeric nature of the lactic acid produced from sugars by lactic bacteria is based on their application; this determination is a criterium for the identification and classification of these microorganisms. The measurement of the lactic acid during vinification allows the early disclosure of the first effects of a bacterial development; inversely it permits the invalidation of the existence of a lactic sourness, which a high volatile acidity might point to. Lastly, the enzymatic measurement of gluconic acid allows the health of the crop to be controlled.

  9. Understanding of alkaline pretreatment parameters for corn stover enzymatic saccharification

    Directory of Open Access Journals (Sweden)

    Chen Ye

    2013-01-01

    Full Text Available Abstract Background Previous research on alkaline pretreatment has mainly focused on optimization of the process parameters to improve substrate digestibility. To achieve satisfactory sugar yield, extremely high chemical loading and enzyme dosages were typically used. Relatively little attention has been paid to reduction of chemical consumption and process waste management, which has proven to be an indispensable component of the bio-refineries. To indicate alkali strength, both alkali concentration in pretreatment solution (g alkali/g pretreatment liquor or g alkali/L pretreatment liquor and alkali loading based on biomass solids (g alkali/g dry biomass have been widely used. The dual approaches make it difficult to compare the chemical consumption in different process scenarios while evaluating the cost effectiveness of this pretreatment technology. The current work addresses these issues through pretreatment of corn stover at various combinations of pretreatment conditions. Enzymatic hydrolysis with different enzyme blends was subsequently performed to identify the effects of pretreatment parameters on substrate digestibility as well as process operational and capital costs. Results The results showed that sodium hydroxide loading is the most dominant variable for enzymatic digestibility. To reach 70% glucan conversion while avoiding extensive degradation of hemicellulose, approximately 0.08 g NaOH/g corn stover was required. It was also concluded that alkali loading based on total solids (g NaOH/g dry biomass governs the pretreatment efficiency. Supplementing cellulase with accessory enzymes such as α-arabinofuranosidase and β-xylosidase significantly improved the conversion of the hemicellulose by 6–17%. Conclusions The current work presents the impact of alkaline pretreatment parameters on the enzymatic hydrolysis of corn stover as well as the process operational and capital investment costs. The high chemical consumption for alkaline

  10. Pregnancy Exercise Increase Enzymatic Antioxidant In Pregnant Women

    Directory of Open Access Journals (Sweden)

    Wagey Freddy Wagey

    2012-01-01

    Full Text Available Objectives: Pregnancy is a vulnerable condition to all kinds of "stress", resulting in changes of physiological and metabolic functions. This research aims to determine effect of exercise during pregnancy in increasing enzymatic antioxidant marked by increase of superoxide dismutase (SOD, gluthation peroxidase (GSHPx, and catalase (CAT levels. Methods: Randomized pre and posttest control group design was employed in this study. A number of 66 pregnant women were recruited in this study and grouped into two groups, i.e 30 of them as control group and the rest as treatment group. Pregnancy exercise was performed to all 36 pregnant women from 20 weeks gestation on treatment group. The exercise was performed in the morning for about 30 minutes, twice a weeks. On the other hand, daily activities was sugested for control group. Student’s t-test was then applied to determine the mean different of treatment and control group with 5 % of significant value. Results: This study reveals that there were significantly higher increase of (superoxide dismutase (SOD, gluthation peroxidase (GSHPx, and catalse (CAT levels of treatment group compare to control group. These enzymatic antioxidant increase among these two group were around 1.36 mg/gHb for SOD; 1.14 IU/gHb for GSHPx; and 0.97 IU/gHb for CAT, (p < 0.05. Clinical outcomes, such as strengten of pelvic muscle and quality of life of treatment group were significantly better compared to control group (p < 0.05. Conclusions: This means that exercise during pregnancy ages of 20 weeks increase enzymatic antioxidant levels SOD, GSHPx, and CAT higher compare to control group without exercise.

  11. Effects of molecular weight of hyaluronic acid on its viscosity and enzymatic activities of lysozyme and peroxidase.

    Science.gov (United States)

    Kim, Jihoon; Chang, Ji-Youn; Kim, Yoon-Young; Kim, Moon-Jong; Kho, Hong-Seop

    2018-02-14

    To investigate the effects of the molecular weight of hyaluronic acid on its viscosity and enzymatic activities of lysozyme and peroxidase in solution and on the hydroxyapatite surface. Hyaluronic acids of four different molecular weights (10 kDa, 100 kDa, 1 MDa, and 2 MDa), hen egg-white lysozyme, bovine lactoperoxidase, and human whole saliva were used. Viscosity values of hyaluronic acids were measured using a cone-and-plate viscometer at six different concentrations (0.1-5.0 mg/mL). Enzymatic activities of lysozyme and peroxidase were examined by hydrolysis of fluorescein-labeled Micrococcus lysodeikticus and oxidation of fluorogenic 2',7'-dichlorofluorescein to fluorescing 2',7'-dichlorofluorescein, respectively. In solution assays, only 2 MDa-hyaluronic acid significantly inhibited lysozyme activities in saliva. In surface assays, hyaluronic acids inhibited lysozyme and peroxidase activities; the inhibitory activities were more apparent with high-molecular-weight ones in saliva than in purified enzymes. The 100 kDa-hyaluronic acid at 5.0 mg/mL, 1 MDa-one at 0.5 mg/mL, and 2 MDa-one at 0.2 mg/mL showed viscosity values similar to those of human whole saliva at a shear rate range required for normal oral functions. The differences among the influences of the three conditions on the enzymatic activities were not statistically significant. High-molecular-weight hyaluronic acids at low concentration and low-molecular-weight ones at high concentration showed viscosity values similar to those of human whole saliva. Inhibitory effects of hyaluronic acids on lysozyme and peroxidase activities were more significant with high-molecular-weight ones on the surface and in saliva compared with in solution and on purified enzymes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Polygalacturonase is the key component in enzymatic retting of flax.

    Science.gov (United States)

    Zhang, J; Henriksson, G; Johansson, G

    2000-07-28

    Seven commercial enzyme mixtures were tested for their ability to perform retting of flax (i.e. to separate flax fibers by partly removal of middle lamella) and were assayed for hydrolysis of xylan, cellulose and four kinds of pectin. The only activity that showed correlation to the ability to perform retting was the degradation of low esterfied pectin. A purified Aspergillus niger polygalacturonase was also shown to be able to perform retting. From this data it is hypothesized that degradation of the smooth regions (i.e. non-methylated polygalacturonase) in the middle lamella pectin is the most important step in enzymatic retting.

  13. Enzymatic hydrolysis of pretreated barley and wheat straw

    DEFF Research Database (Denmark)

    Rosgaard, Lisa

    2007-01-01

    feeding strategy to increase the substrate loading in the hydrolysis reaction. The substrate for the enzymatic hydrolysis was primarily steam pretreated wheat and barley straw since these substrates were the primary feedstocks for the Babilafuente Bioethanol process. The initial work showed...... addition of hemicellulase activities to complement the cellulase activities found in Celluclast. Further improving the hydrolysis process in relation to the Babilafuente Bioethanol process might be achieved applying a substrate fed-batch strategy, if optimised in relation to timing of the substrate...

  14. Sugar ester surfactants: enzymatic synthesis and applications in food industry.

    Science.gov (United States)

    Neta, Nair S; Teixeira, José A; Rodrigues, Lígia R

    2015-01-01

    Sugar esters are non-ionic surfactants that can be synthesized in a single enzymatic reaction step using lipases. The stability and efficiency of lipases under unusual conditions and using non-conventional media can be significantly improved through immobilization and protein engineering. Also, the development of de novo enzymes has seen a significant increase lately under the scope of the new field of synthetic biology. Depending on the esterification degree and the nature of fatty acid and/or sugar, a range of sugar esters can be synthesized. Due to their surface activity and emulsifying capacity, sugar esters are promising for applications in food industry.

  15. Enzymatic description of the anhydrofructose pathway of glycogen degradation. I

    DEFF Research Database (Denmark)

    Yu, Shukun; Refdahl, Charlotte; Lundt, Inge

    2004-01-01

    The anhydrofructose pathway describes the degradation of glycogen and starch to metabolites via 1,5-anhydro-D-fructose (1,5AnFru). The enzyme catalyzing the first reaction step of this pathway, i.e., a-1,4-glucan lyase (EC 4.2.1.13), has been purified, cloned and characterized from fungi and red...... possessed all enzymes needed for conversion of glycogen to APP, an a-1,4-glucan lyase from this fungus was isolated and partially sequenced. Based on this work, a scheme of the enzymatic description of the anhydrofructose pathway in A. melaloma was proposed. Keywords: Anhydrofructose pathway; Anthracobia...

  16. Enzymatic synthesis of hydrophobic compounds integrated with membrane separation

    Directory of Open Access Journals (Sweden)

    Noworyta Andrzej

    2016-03-01

    Full Text Available The enzymatic synthesis of a highly hydrophobic product (dipeptide precursor in which the reaction is accompanied by the mass transfer of the reaction product to the organic phase and the substrates to the water phase is considered. Equations describing both continuous and batch processes are formulated. The range of variability in the operating parameters of such a bioreactor is specified, and the correlations reported in the literature to describe mass transfer in the membrane contactor are validated. The proposed process was verified experimentally, and good agreement between the determined and calculated concentrations was obtained in both phases.

  17. The Mechanisms of Plant Cell Wall Deconstruction during Enzymatic Hydrolysis

    DEFF Research Database (Denmark)

    Thygesen, Lisbeth Garbrecht; E. Thybring, Emil; Johansen, Katja Salomon

    2014-01-01

    Mechanical agitation during enzymatic hydrolysis of insoluble plant biomass at high dry matter contents is indispensable for the initial liquefaction step in biorefining. It is known that particle size reduction is an important part of liquefaction, but the mechanisms involved are poorly understood....... Here we put forward a simple model based on mechanical principles capable of capturing the result of the interaction between mechanical forces and cell wall weakening via hydrolysis of glucosidic bonds. This study illustrates that basic material science insights are relevant also within biochemistry...

  18. Threshold sensing through a synthetic enzymatic reaction-diffusion network.

    Science.gov (United States)

    Semenov, Sergey N; Markvoort, Albert J; de Greef, Tom F A; Huck, Wilhelm T S

    2014-07-28

    A wet stamping method to precisely control concentrations of enzymes and inhibitors in place and time inside layered gels is reported. By combining enzymatic reactions such as autocatalysis and inhibition with spatial delivery of components through soft lithographic techniques, a biochemical reaction network capable of recognizing the spatial distribution of an enzyme was constructed. The experimental method can be used to assess fundamental principles of spatiotemporal order formation in chemical reaction networks. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Fed-Batch Feeding Strategies for Enzymatic Biodiesel Production

    DEFF Research Database (Denmark)

    Price, Jason Anthony; Nordblad, Mathias; Woodley, John

    2014-01-01

    of the differences in the interfacial and bulk concentrations of the enzyme. The model is then used to evaluate various feeding strategies to improve the enzymatic biodiesel production. The feeding strategies investigated, gave insight into how the methanol should be fed to potentially mitigate enzyme deactivation...... while improving the biodiesel yield. The best experimental results gave a yield of 703 .76 g FAME L-1 and a reactor productivity of 28.12 g FAME L-1 h-1. In comparison, to reach the same yield, the optimised two step feeding strategy took 6.25 hours less, which equates to an increase the reactor...

  20. Modelling and operation of reactors for enzymatic biodiesel production

    DEFF Research Database (Denmark)

    Price, Jason Anthony

    to the production of high fructose corn syrup, upgrading of fats and oils and biodiesel production to name a few. Despite these examples of industrial enzymatic applications, it is still not “clear cut” how to implement biocatalyst in industry and how best to optimize the processes. This is because the processing...... aspects of the enzyme with reaction/reactor engineering is performed. This strategy is applied to a case study of biodiesel production catalysed by a liquid enzyme formulation. The use of enzymes for biodiesel production is still in its infancy with non-optimized process designs. Furthermore is it unclear...