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Sample records for high cuprous oxidase

  1. Cuprous halides semiconductors as a new means for highly efficient light-emitting diodes

    Science.gov (United States)

    Ahn, Doyeol; Park, Seoung-Hwan

    2016-01-01

    In group-III nitrides in use for white light-emitting diodes (LEDs), optical gain, measure of luminous efficiency, is very low owing to the built-in electrostatic fields, low exciton binding energy, and high-density misfit dislocations due to lattice-mismatched substrates. Cuprous halides I-VII semiconductors, on the other hand, have negligible built-in field, large exciton binding energies and close lattice matched to silicon substrates. Recent experimental studies have shown that the luminescence of I-VII CuCl grown on Si is three orders larger than that of GaN at room temperature. Here we report yet unexplored potential of cuprous halides systems by investigating the optical gain of CuCl/CuI quantum wells. It is found that the optical gain and the luminescence are much larger than that of group III-nitrides due to large exciton binding energy and vanishing electrostatic fields. We expect that these findings will open up the way toward highly efficient cuprous halides based LEDs compatible to Si technology. PMID:26880097

  2. One-step green synthesis of cuprous oxide crystals with truncated octahedra shapes via a high pressure flux approach

    International Nuclear Information System (INIS)

    Li Benxian; Wang Xiaofeng; Xia Dandan; Chu Qingxin; Liu Xiaoyang; Lu Fengguo; Zhao Xudong

    2011-01-01

    Cuprous oxide (Cu 2 O) was synthesized via reactions between cupric oxide (CuO) and copper metal (Cu) at a low temperature of 300 deg. C. This progress is green, environmentally friendly and energy efficient. Cu 2 O crystals with truncated octahedra morphology were grown under high pressure using sodium hydroxide (NaOH) and potassium hydroxide (KOH) with a molar ratio of 1:1 as a flux. The growth mechanism of Cu 2 O polyhedral microcrystals are proposed and discussed. - Graphical Abstract: The Cu 2 O crystals with truncated octahedral shape were one-step synthesized in high yield via high pressure flux method for the first time, which is green and environmentally friendly. The mechanisms of synthesis and crystal growth were discussed in this paper. Highlights: → Cuprous oxide was one-step green synthesized by high pressure flux method. → The approach was based on the reverse dismutation reactions between cupric oxide and copper metal. → This progress is green, environmentally friendly and energy efficient. → The synthesized Cu2O crystals were of truncated octahedra morphology.

  3. Radiation annealing in cuprous oxide

    DEFF Research Database (Denmark)

    Vajda, P.

    1966-01-01

    Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square...

  4. Preparation of 3D nanoporous copper-supported cuprous oxide for high-performance lithium ion battery anodes.

    Science.gov (United States)

    Liu, Dequan; Yang, Zhibo; Wang, Peng; Li, Fei; Wang, Desheng; He, Deyan

    2013-03-07

    Three-dimensional (3D) nanoporous architectures can provide efficient and rapid pathways for Li-ion and electron transport as well as short solid-state diffusion lengths in lithium ion batteries (LIBs). In this work, 3D nanoporous copper-supported cuprous oxide was successfully fabricated by low-cost selective etching of an electron-beam melted Cu(50)Al(50) alloy and subsequent in situ thermal oxidation. The architecture was used as an anode in lithium ion batteries. In the first cycle, the sample delivered an extremely high lithium storage capacity of about 2.35 mA h cm(-2). A high reversible capacity of 1.45 mA h cm(-2) was achieved after 120 cycles. This work develops a promising approach to building reliable 3D nanostructured electrodes for high-performance lithium ion batteries.

  5. Copper-doped silica cuprous sulfate: A highly efficient heterogeneous nano-catalyst for one-pot three-component synthesis of 1-H-2-substituted benzimidazoles from 2-bromoanilines, aldehydes, and [bmim]N3

    Directory of Open Access Journals (Sweden)

    Somayeh Behrouz

    2018-03-01

    Full Text Available A facile and highly efficient one-pot three-component synthesis of 1-H-2-substituted benzimidazole derivatives from readily available substrates catalyzed by copper-doped silica cuprous sulfate (CDSCS is described. In this method, treatment of diverse 2-bromoanilines, aldehydes, and [bmim]N3 in DMF at 110 °C in the presence of CDSCS as a highly efficient heterogeneous nano-catalyst affords the corresponding 1-H-2-substituted benzimidazoles in good to excellent yields. The CDSCS is an inexpensive and stable nano-catalyst that could be simply prepared, recovered and reused for many consecutive reaction runs without significant loss of its activity.

  6. 21 CFR 184.1265 - Cuprous iodide.

    Science.gov (United States)

    2010-04-01

    ... the following specific limitations: Category of food Maximum treatment level in food Functional use... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cuprous iodide. 184.1265 Section 184.1265 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN...

  7. Green chemistry synthesis of nano-cuprous oxide.

    Science.gov (United States)

    Ceja-Romero, L R; Ortega-Arroyo, L; Ortega Rueda de León, J M; López-Andrade, X; Narayanan, J; Aguilar-Méndez, M A; Castaño, V M

    2016-04-01

    Green chemistry and a central composite design, to evaluate the effect of reducing agent, temperature and pH of the reaction, were employed to produce controlled cuprous oxide (Cu2O) nanoparticles. Response surface method of the ultraviolet-visible spectroscopy is allowed to determine the most relevant factors for the size distribution of the nanoCu2O. X-ray diffraction reflections correspond to a cubic structure, with sizes from 31.9 to 104.3 nm. High-resolution transmission electron microscopy reveals that the different shapes depend strongly on the conditions of the green synthesis.

  8. Indanones as high-potency reversible inhibitors of monoamine oxidase.

    Science.gov (United States)

    Mostert, Samantha; Petzer, Anél; Petzer, Jacobus P

    2015-05-01

    Recent reports document that α-tetralone (3,4-dihydro-2H-naphthalen-1-one) is an appropriate scaffold for the design of high-potency monoamine oxidase (MAO) inhibitors. Based on the structural similarity between α-tetralone and 1-indanone, the present study involved synthesis of 34 1-indanone and related indane derivatives as potential inhibitors of recombinant human MAO-A and MAO-B. The results show that C6-substituted indanones are particularly potent and selective MAO-B inhibitors, with IC50 values ranging from 0.001 to 0.030 μM. C5-Substituted indanone and indane derivatives are comparatively weaker MAO-B inhibitors. Although the 1-indanone and indane derivatives are selective inhibitors of the MAO-B isoform, a number of homologues are also potent MAO-A inhibitors, with three homologues possessing IC50 values 1-indanone as a reversible MAO inhibitor with a competitive mode of inhibition. It may be concluded that 1-indanones are promising leads for the design of therapies for neurodegenerative and neuropsychiatric disorders such as Parkinson's disease and depression. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Effect of high pressure on peanut allergens in the presence of polyphenol oxidase and caffeic acid

    Science.gov (United States)

    High pressure (HP) enhances enzymatic reactions. Because polyphenol oxidase (PPO) is an enzyme, and reduces IgE binding of peanut allergens in presence of caffeic acid (CA), we postulated that a further reduction in IgE binding can be achieved, using HP together with PPO and CA. Peanut extracts cont...

  10. Cuprous oxide thin films grown by hydrothermal electrochemical deposition technique

    International Nuclear Information System (INIS)

    Majumder, M.; Biswas, I.; Pujaru, S.; Chakraborty, A.K.

    2015-01-01

    Semiconducting cuprous oxide films were grown by a hydrothermal electro-deposition technique on metal (Cu) and glass (ITO) substrates between 60 °C and 100 °C. X-ray diffraction studies reveal the formation of cubic cuprous oxide films in different preferred orientations depending upon the deposition technique used. Film growth, uniformity, grain size, optical band gap and photoelectrochemical response were found to improve in the hydrothermal electrochemical deposition technique. - Highlights: • Cu 2 O thin films were grown on Cu and glass substrates. • Conventional and hydrothermal electrochemical deposition techniques were used. • Hydrothermal electrochemical growth showed improved morphology, thickness and optical band gap

  11. Glucose Oxidase Directly Immobilized onto Highly Porous Gold Electrodes for Sensing and Fuel Cell applications

    International Nuclear Information System (INIS)

    Toit, Hendrik du; Di Lorenzo, Mirella

    2014-01-01

    Highlights: • Electrochemical adsorption of glucose oxidase (GOx) on highly porous gold (hPG); • Rapid one-step immobilisation protocol with no use of expensive and/or harsh reagents; • Linear response to glucose in the range 50 μM -10 mM; • Lower detection limit, stable over 5 days: 25 μM. • The use of the GOx-hPG in a fuel cell lead to the peak power density of 6 μW cm −2 . - Abstract: The successful implementation of redox-enzyme electrodes in biosensors and enzymatic biofuel cells has been the subject of extensive research. For high sensitivity and high energy-conversion efficiency, the effective electron transfer at the protein-electrode interface has a key role. This is difficult to achieve in the case of glucose oxidase, due to the fact that for this enzyme the redox centre is buried inside the structure, far from any feasible electrode binding sites. This study reports, a simple and rapid methodology for the direct immobilisation of glucose oxidase into highly porous gold electrodes. When the resulting electrode was tested as glucose sensor, a Michaelis-Menten kinetic trend was observed, with a detection limit of 25 μM. The bioelectrode sensitivity, calculated against the superficial surface area of the bioelectrode, was of 22.7 ± 0.1 μA mM −1 cm −2 . This glucose oxidase electrode was also tested as an anode in a glucose/O 2 enzymatic biofuel cell, leading to a peak power density of 6 μW cm −2 at a potential of 0.2 V

  12. A highly sensitive electrochemical glucose sensor structuring with nickel hydroxide and enzyme glucose oxidase

    International Nuclear Information System (INIS)

    Mathew, Manjusha; Sandhyarani, N.

    2013-01-01

    Graphical abstract: A combination of Ni 2+ /Ni 3+ redox couple and glucose oxidase has successfully been exploited for the realization of a highly sensitive glucose sensor for the first time. -- Highlights: • A multilayered glucose biosensor with enhanced sensitivity was fabricated. • Combination of Ni 2+ /Ni 3+ redox couple and glucose oxidase has been exploited for the first time. • Exhibits a lower detection limit of 100 nM with a high sensitivity of 16,840 μA mM −1 cm −2 . • The surface shows a low Michaelis–Menten constant value of 2.4 μM. • Detailed mechanism of sensing was proposed and justified. -- Abstract: A multilayered glucose biosensor with enhanced electron transport was fabricated via the sequential electrodeposition of chitosan gold nanocomposite (CGNC) and nickel hydroxide (Ni(OH) 2 ) on a bare gold electrode and subsequent immobilization of glucose oxidase. A thin film of Ni(OH) 2 deposited on CGNC modified gold electrode serves as an electrochemical redox probe as well as a matrix for the immobilization of glucose oxidase retaining its activity. Electron transport property of CGNC has been exploited to enhance the electron transport between the analyte and electrode. Electrochemical characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. Under optimal conditions the biosensor exhibits a linear range from 1 μM to 100 μM with a limit of detection (lod) down to 100 nM. The sensor shows a low Michaelis-Menten constant value of 2.4 μM indicates the high affinity of enzyme to the analyte points to the retained activity of enzyme after immobilization. The present glucose sensor with the high selectivity, sensitivity and stability is promising for practical clinical applications

  13. Electrochemical behaviour of cuprous complexes of dithia-alkanedicarboxylic acids

    NARCIS (Netherlands)

    Pieterse, M.M.J.; Janssen, L.J.J.

    1972-01-01

    The composition and electrochemical behaviour of the cuprous complexes of dithia-alkanedicarboxylic acids viz., 2,5-dithiahexane-1,6-dicarboxylic acid (I); 3,6 dithiaoctane-1,8-dicarboxylic acid (II); 4,7-dithiadecane-1,10-dicarboxylic acid (III) and 2,2,

  14. Optimization of Glucose oxidase towards oxygen independency and high mediator activity for amperometric glucose determination in diabetes analytics

    OpenAIRE

    Arango Gutierrez, Erik Uwe

    2015-01-01

    Glucose oxidase is an oxidoreductase exhibiting a high β-D-glucose specificity and high stability which renders glucose oxidase well-suited for applications in diabetes care. Nevertheless, GOx activity is highly oxygen dependent which can lead to inaccuracies in amperometric β-D-glucose determinations. Therefore a directed evolution campaign with two rounds of random mutagenesis (SeSaM followed by epPCR), site saturation mutagenesis studies, and one simultaneous site saturation library (OmniC...

  15. Highly Promiscuous Oxidases Discovered in the Bovine Rumen Microbiome

    Directory of Open Access Journals (Sweden)

    Lisa Ufarté

    2018-05-01

    Full Text Available The bovine rumen hosts a diverse microbiota, which is highly specialized in the degradation of lignocellulose. Ruminal bacteria, in particular, are well equipped to deconstruct plant cell wall polysaccharides. Nevertheless, their potential role in the breakdown of the lignin network has never been investigated. In this study, we used functional metagenomics to identify bacterial redox enzymes acting on polyaromatic compounds. A new methodology was developed to explore the potential of uncultured microbes to degrade lignin derivatives, namely kraft lignin and lignosulfonate. From a fosmid library covering 0.7 Gb of metagenomic DNA, three hit clones were identified, producing enzymes able to oxidize a wide variety of polyaromatic compounds without the need for the addition of copper, manganese, or mediators. These promiscuous redox enzymes could thus be of potential interest both in plant biomass refining and dye remediation. The enzymes were derived from uncultured Clostridia, and belong to complex gene clusters involving proteins of different functional types, including hemicellulases, which likely work in synergy to produce substrate degradation.

  16. Cathodoluminescence and ion implantation of cadmium sulphide/cuprous sulphide solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Glew, R W; Bryant, F J

    1975-10-01

    By the use of implantation with copper ions or oxygen ions of 50 keV energy, changes in the cathodoluminescence emission spectrum from cadmium sulfide/cuprous sulfide thin film manufactured solar cells have been correlated with changes in the phases of the cuprous sulfide layer. Thus, monitoring the relative intensities of cathodoluminescence emission bands affords a method of assessing the cuprous sulfide layer and possibly predicting the performance of the cells.

  17. Electrochromism of the electroless deposited cuprous oxide films

    International Nuclear Information System (INIS)

    Neskovska, R.; Ristova, M.; Velevska, J.; Ristov, M.

    2007-01-01

    Thin cuprous oxide films were prepared by a low cost, chemical deposition (electroless) method onto glass substrates pre-coated with fluorine doped tin oxide. The X-ray diffraction pattern confirmed the Cu 2 O composition of the films. Visible transmittance spectra of the cuprous oxide films were studied for the as-prepared, colored and bleached films. The cyclic voltammetry study showed that those films exhibited cathode coloring electrochromism, i.e. the films showed change of color from yellowish to black upon application of an electric field. The transmittance across the films for laser light of 670 nm was found to change due to the voltage change for about 50%. The coloration memory of those films was also studied during 6 h, ex-situ. The coloration efficiency at 670 nm was calculated to be 37 cm 2 /C

  18. Myeloperoxidase amplified high glucose-induced endothelial dysfunction in vasculature: Role of NADPH oxidase and hypochlorous acid.

    Science.gov (United States)

    Tian, Rong; Ding, Yun; Peng, Yi-Yuan; Lu, Naihao

    2017-03-11

    Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived reactive oxygen species (ROS) such as superoxide and hydrogen peroxide (H 2 O 2 ), have emerged as important molecules in the pathogenesis of diabetic endothelial dysfunction. Additionally, neutrophils-derived myeloperoxidase (MPO) and MPO-catalyzed hypochlorous acid (HOCl) play important roles in the vascular injury. However, it is unknown whether MPO can use vascular-derived ROS to induce diabetic endothelial dysfunction. In the present study, we demonstrated that NADPH oxidase was the main source of ROS formation in high glucose-cultured human umbilical vein endothelial cells (HUVECs), and played a critical role in high glucose-induced endothelial dysfunction such as cell apoptosis, loss of cell viability and reduction of nitric oxide (NO). However, the addition of MPO could amplify the high glucose-induced endothelial dysfunction which was inhibited by the presence of apocynin (NADPH oxidase inhibitor), catalase (H 2 O 2 scavenger), or methionine (HOCl scavenger), demonstrating the contribution of NADPH oxidase-H 2 O 2 -MPO-HOCl pathway in the MPO/high glucose-induced vascular injury. In high glucose-incubated rat aortas, MPO also exacerbated the NADPH oxidase-induced impairment of endothelium-dependent relaxation. Consistent with these in vitro data, in diabetic rat aortas, both MPO expresion and NADPH oxidase activity were increased while the endothelial function was simultaneously impaired. The results suggested that vascular-bound MPO could amplify high glucose-induced vascular injury in diabetes. MPO-NADPH oxidase-HOCl may represent an important pathogenic pathway in diabetic vascular diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Size-selective QD@MOF core-shell nanocomposites for the highly sensitive monitoring of oxidase activities.

    Science.gov (United States)

    Wang, Ke; Li, Nan; Zhang, Jing; Zhang, Zhiqi; Dang, Fuquan

    2017-01-15

    In this work, we proposed a novel and facile method to monitor oxidase activities based on size-selective fluorescent quantum dot (QD)@metal-organic framework (MOF) core-shell nanocomposites (CSNCPs). The CSNCPs were synthesized from ZIF-8 and CdTe QDs in aqueous solution in 40min at room temperature with stirring. The prepared CdTe@ZIF-8 CSNCPs , which have excellent water dispersibility and stability, displays distinct fluorescence responses to hole scavengers of different molecular sizes (e.g., H 2 O 2 , substrate, and oxidase) due to the aperture limitation of the ZIF-8 shell. H 2 O 2 can efficiently quench the fluorescence of CdTe@ZIF-8 CSNCPs over a linearity range of 1-100nM with a detection limit of 0.29nM, whereas large molecules such as substrate and oxidase have very little effect on its fluorescence. Therefore, the highly sensitive detection of oxidase activities was achieved by monitoring the fluorescence quenching of CdTe@ZIF-8 CSNCPs by H 2 O 2 produced in the presence of substrate and oxidase, which is proportional to the oxidase activities. The linearity ranges of the uricase and glucose oxidase activity are 0.1-50U/L and 1-100U/L, respectively, and their detection limits are 0.024U/L and 0.26U/L, respectively. Therefore, the current QD@MOF CSNCPs based sensing system is a promising, widely applicable means of monitoring oxidase activities in biochemical research. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Cuprous Oxide Scale up: Gram Production via Bulk Synthesis using Classic Solvents at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hall, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Han, T. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-07

    Cuprous oxide is a p-type semiconducting material that has been highly researched for its interesting properties. Many small-scale syntheses have exhibited excellent control over size and morphology. As the demand for cuprous oxide grows, the synthesis method need to evolve to facilitate large-scale production. This paper supplies a facile bulk synthesis method for Cu₂O on average, 1-liter reaction volume can produce 1 gram of particles. In order to study the shape and size control mechanisms on such a scale, the reaction volume was diminished to 250 mL producing on average 0.3 grams of nanoparticles per batch. Well-shaped nanoparticles have been synthesized using an aqueous solution of CuCl₂, NaOH, SDS surfactant, and NH₂OH-HCl at mild temperatures. The time allotted between the addition of NaOH and NH₂OH-HCl was determined to be critical for Cu(OH)2 production, an important precursor to the final produce The effects of stirring rates on a large scale was also analyzed during reagent addition and post reagent addition. A morphological change from rhombic dodecahedra to spheres occurred as the stirring speed was increased. The effects of NH₂OH-HCl concentration were also studied to control the etching effects of the final product.

  1. Ultra-high-throughput screening method for the directed evolution of glucose oxidase.

    Science.gov (United States)

    Ostafe, Raluca; Prodanovic, Radivoje; Nazor, Jovana; Fischer, Rainer

    2014-03-20

    Glucose oxidase (GOx) is used in many industrial processes that could benefit from improved versions of the enzyme. Some improvements like higher activity under physiological conditions and thermal stability could be useful for GOx applications in biosensors and biofuel cells. Directed evolution is one of the currently available methods to engineer improved GOx variants. Here, we describe an ultra-high-throughput screening system for sorting the best enzyme variants generated by directed evolution that incorporates several methodological refinements: flow cytometry, in vitro compartmentalization, yeast surface display, fluorescent labeling of the expressed enzyme, delivery of glucose substrate to the reaction mixture through the oil phase, and covalent labeling of the cells with fluorescein-tyramide. The method enables quantitative screening of gene libraries to identify clones with improved activity and it also allows cells to be selected based not only on the overall activity but also on the specific activity of the enzyme. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. High electro-catalytic activities of glucose oxidase embedded one-dimensional ZnO nanostructures

    International Nuclear Information System (INIS)

    Sarkar, Nirmal K; Bhattacharyya, Swapan K

    2013-01-01

    One-dimensional ZnO nanorods and nanowires are separately synthesized on Zn substrate by simple hydrothermal processes at low temperatures. Electro-catalytic responses of glucose oxidase/ZnO/Zn electrodes using these two synthesized nanostructures of ZnO are reported and compared with others available in literature. It is apparent the Michaelis–Menten constant, K M app , for the present ZnO nanowire, having a greater aspect ratio, is found to be the lowest when compared with others. This sensor shows lower oxidation peak potential with a long detection range of 6.6 μM–380 mM and the highest sensitivity of ∼35.1 μA cm −2 mM −1 , among the reported values in the literature. Enzyme catalytic efficiency and turnover numbers are also found to be remarkably high. (paper)

  3. Tea polyphenols alleviate high fat and high glucose-induced endothelial hyperpermeability by attenuating ROS production via NADPH oxidase pathway.

    Science.gov (United States)

    Zuo, Xuezhi; Tian, Chong; Zhao, Nana; Ren, Weiye; Meng, Yi; Jin, Xin; Zhang, Ying; Ding, Shibin; Ying, Chenjiang; Ye, Xiaolei

    2014-03-02

    Hyperglycemia-induced endothelial hyperpermeability is crucial to cardiovascular disorders and macro-vascular complications in diabetes mellitus. The objective of this study is to investigate the effects of green tea polyphenols (GTPs) on endothelial hyperpermeability and the role of nicotinamide adenine dinucleotide phosphate (NADPH) pathway. Male Wistar rats fed on a high fat diet (HF) were treated with GTPs (0, 0.8, 1.6, 3.2 g/L in drinking water) for 26 weeks. Bovine aortic endothelial cells (BAECs) were treated with high glucose (HG, 33 mmol/L) and GTPs (0.0, 0.4, or 4 μg/mL) for 24 hours in vitro. The endothelial permeabilities in rat aorta and monolayer BAECs were measured by Evans blue injection method and efflux of fluorescein isothiocyanate (FITC)-dextran, respectively. The reactive oxygen species (ROS) levels in rat aorta and monolayer BAECs were measured by dihydroethidium (DHE) and 2', 7'-dichloro-fluorescein diacetate (DCFH-DA) fluorescent probe, respectively. Protein levels of NADPH oxidase subunits were determined by Western-blot. HF diet-fed increased the endothelial permeability and ROS levels in rat aorta while HG treatments increased the endothelial permeability and ROS levels in cultured BAECs. Co-treatment with GTPs alleviated those changes both in vivo and in vitro. In in vitro studies, GTPs treatments protected against the HG-induced over-expressions of p22phox and p67phox. Diphenylene iodonium chloride (DPI), an inhibitor of NADPH oxidase, alleviated the hyperpermeability induced by HG. GTPs could alleviate endothelial hyperpermeabilities in HF diet-fed rat aorta and in HG treated BAECs. The decrease of ROS production resulting from down-regulation of NADPH oxidase contributed to the alleviation of endothelial hyperpermeability.

  4. Cuprous sulfide as a film insulation for superconductors

    International Nuclear Information System (INIS)

    Wagner, G.R.; Uphoff, J.H.; Vecchio, P.D.

    1982-01-01

    The LCP test coil utilizes a conductor of forced-flow design having 486 strands of multifilametary Nb 3 Sn compacted in a stainless steel sheath. The impetus for the work reported here stemmed from the need for some form of insulation for those strands to prevent sintering during reaction and to reduce ac losses. The work reported here experimented with cuprous sulfide coatings at various coating rates and thicknesses. Two solenoids that were wound with cuprous sulfide-coated wires and heat-treated at 700 degrees C were found to demonstrate that the film is effective in providing turn-to-turn insulation for less than about 0.5V between turns. The sulfide layer provided a metal-semiconductor junction which became conducting at roughly 0.5V. Repeated cycling of the coil voltage in excess of that value produced no damage to the sulfide layer. The junction provided self-protection for the coil as long as the upper allowable current density in the sulfide was not exceeded. No training was apparent up to 6.4 T

  5. Resveratrol protects vascular endothelial cells from high glucose-induced apoptosis through inhibition of NADPH oxidase activation-driven oxidative stress.

    Science.gov (United States)

    Chen, Feng; Qian, Li-Hua; Deng, Bo; Liu, Zhi-Min; Zhao, Ying; Le, Ying-Ying

    2013-09-01

    Hyperglycemia-induced oxidative stress has been implicated in diabetic vascular complications in which NADPH oxidase is a major source of reactive oxygen species (ROS) generation. Resveratrol is a naturally occurring polyphenol, which has vasoprotective effects in diabetic animal models and inhibits high glucose (HG)-induced oxidative stress in endothelial cells. We aimed to examine whether HG-induced NADPH oxidase activation and ROS production contribute to glucotoxicity to endothelial cells and the effect of resveratrol on glucotoxicity. Using a murine brain microvascular endothelial cell line bEnd3, we found that NADPH oxidase inhibitor (apocynin) and resveratrol both inhibited HG-induced endothelial cell apoptosis. HG-induced elevation of NADPH oxidase activity and production of ROS were inhibited by apocynin, suggesting that HG induces endothelial cell apoptosis through NADPH oxidase-mediated ROS production. Mechanistic studies revealed that HG upregulated NADPH oxidase subunit Nox1 but not Nox2, Nox4, and p22(phox) expression through NF-κB activation, which resulted in elevation of NADPH oxidase activity and consequent ROS production. Resveratrol prevented HG-induced endothelial cell apoptosis through inhibiting HG-induced NF-κB activation, NADPH oxidase activity elevation, and ROS production. HG induces endothelial cell apoptosis through NF-κB/NADPH oxidase/ROS pathway, which was inhibited by resveratrol. Our findings provide new potential therapeutic targets against brain vascular complications of diabetes. © 2013 John Wiley & Sons Ltd.

  6. Amide group anchored glucose oxidase based anodic catalysts for high performance enzymatic biofuel cell

    Science.gov (United States)

    Chung, Yongjin; Ahn, Yeonjoo; Kim, Do-Heyoung; Kwon, Yongchai

    2017-01-01

    A new enzyme catalyst is formed by fabricating gold nano particle (GNP)-glucose oxidase (GOx) clusters that are then attached to polyethyleneimine (PEI) and carbon nanotube (CNT) with cross-linkable terephthalaldehyde (TPA) (TPA/[CNT/PEI/GOx-GNP]). Especially, amide bonds belonging to TPA play an anchor role for incorporating rigid bonding among GNP, GOx and CNT/PEI, while middle size GNP is well bonded with thiol group of GOx to form strong GNP-GOx cluster. Those bonds are identified by chemical and electrochemical characterizations like XPS and cyclic voltammogram. The anchording effect of amide bonds induces fast electron transfer and strong chemical bonding, resulting in enhancements in (i) catalytic activity, (ii) amount of immobilized GOx and (ii) performance of enzymatic biofuel cell (EBC) including the catalyst. Regarding the catalytic activity, the TPA/[CNT/PEI/GOx-GNP] produces high electron transfer rate constant (6 s-1), high glucose sensitivity (68 μA mM-1 cm-2), high maximum current density (113 μA cm-2), low charge transfer resistance (17.0 Ω cm2) and long-lasting durability while its chemical structure is characterized by XPS confirming large portion of amide bond. In EBC measurement, it has high maximum power density (0.94 mW cm-2) compatible with catalytic acitivity measurements.

  7. High throughput Screening to Identify Natural Human Monoamine Oxidase B Inhibitors

    Science.gov (United States)

    Mazzio, E; Deiab, S; Park, K; Soliman, KFA

    2012-01-01

    Age-related increase in monoamine oxidase B (MAO-B) may contribute to CNS neurodegenerative diseases. Moreover, MAO-B inhibitors are used in the treatment of idiopathic Parkinson disease as preliminary monotherapy or adjunct therapy with L-dopa. To date, meager natural sources of MAO-B inhibitors have been identified, and the relative strength, potency and rank of many plants relative to standard drugs such as Selegiline (L-deprenyl, Eldepryl) are not known. In this work, we developed and utilized a high throughput enzyme microarray format to screen and evaluate 905 natural product extracts (0.025–.7 mg/ml) to inhibit human MAO-B derived from BTI-TN-5B1-4 cells infected with recombinant baculovirus. The protein sequence of purified enzyme was confirmed using 1D gel electrophoresis-matrix assisted laser desorption ionization-time-of-flight-tandem mass spectroscopy, and enzyme activity was confirmed by [1] substrate conversion (3-mM benzylamine) to H202 and [2] benzaldehyde. Of the 905 natural extracts tested, the lowest IC50s [Comfrey, Bringraj, Skullcap, Kava-kava, Wild Indigo, Gentian and Green Tea. In conclusion, the data reflect relative potency information by rank of commonly used herbs and plants that contain human MAO-B inhibitory properties in their natural form. PMID:22887993

  8. Directing the Branching Growth of Cuprous Oxide by OH- Ions

    Science.gov (United States)

    Chen, Kunfeng; Si, Yunfei; Xue, Dongfeng

    The effect of OH- ions on the branching growth of cuprous oxide microcrystals was systematically studied by a reduction route, where copper-citrate complexes were reduced by glucose under alkaline conditions. Different copper salts including Cu(NO3)2, CuCl2, CuSO4, and Cu(Ac)2 were used in this work. The results indicate that the Cu2O branching growth habit is closely correlated to the concentration of OH- ions, which plays an important role in directing the diffusion-limited branching growth of Cu2O and influencing the reduction power of glucose. A variety of Cu2O branching patterns including 6-pod, 8-pod and 24-pod branches, have been achieved without using template and surfactant. The current method can provide a good platform for studying the growth mechanism of microcrystal branching patterns.

  9. Cuprous oxide nanoparticles selectively induce apoptosis of tumor cells

    Science.gov (United States)

    Wang, Ye; Zi, Xiao-Yuan; Su, Juan; Zhang, Hong-Xia; Zhang, Xin-Rong; Zhu, Hai-Ying; Li, Jian-Xiu; Yin, Meng; Yang, Feng; Hu, Yi-Ping

    2012-01-01

    In the rapid development of nanoscience and nanotechnology, many researchers have discovered that metal oxide nanoparticles have very useful pharmacological effects. Cuprous oxide nanoparticles (CONPs) can selectively induce apoptosis and suppress the proliferation of tumor cells, showing great potential as a clinical cancer therapy. Treatment with CONPs caused a G1/G0 cell cycle arrest in tumor cells. Furthermore, CONPs enclosed in vesicles entered, or were taken up by mitochondria, which damaged their membranes, thereby inducing apoptosis. CONPs can also produce reactive oxygen species (ROS) and initiate lipid peroxidation of the liposomal membrane, thereby regulating many signaling pathways and influencing the vital movements of cells. Our results demonstrate that CONPs have selective cytotoxicity towards tumor cells, and indicate that CONPs might be a potential nanomedicine for cancer therapy. PMID:22679374

  10. Microwave-assisted synthesis and optical properties of cuprous oxide micro/nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Dandan [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Du, Yi, E-mail: duyi234@126.com [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Tian, Xiuying, E-mail: xiuyingt@yahoo.com [Department of Chemistry and Materials Science, Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Li, Zhongfu; Chen, Zhongtao; Zhu, Chaofeng [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China)

    2014-12-15

    Graphical abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. Growth mechanism of the prepared Cu{sub 2}O microcrystals were investigated carefully. Furthermore, the optical properties of the prepared cuprous oxide microcrystals were investigated by UV–vis diffuse reflectance spectroscopy, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies. - Abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. It was observed that the addition amounts of NaOH had a prominent effect on the morphologies and size of cuprous oxide products, and microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. The as-obtained samples were characterized by X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). The results indicated that the samples were pure cuprous oxide. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Furthermore, the UV–vis diffuse reflectance spectroscopy was used to investigate the optical properties of the prepared cuprous oxide microcrystals, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies.

  11. A high-throughput colorimetric assay for glucose detection based on glucose oxidase-catalyzed enlargement of gold nanoparticles

    Science.gov (United States)

    Xiong, Yanmei; Zhang, Yuyan; Rong, Pengfei; Yang, Jie; Wang, Wei; Liu, Dingbin

    2015-09-01

    We developed a simple high-throughput colorimetric assay to detect glucose based on the glucose oxidase (GOx)-catalysed enlargement of gold nanoparticles (AuNPs). Compared with the currently available glucose kit method, the AuNP-based assay provides higher clinical sensitivity at lower cost, indicating its great potential to be a powerful tool for clinical screening of glucose.We developed a simple high-throughput colorimetric assay to detect glucose based on the glucose oxidase (GOx)-catalysed enlargement of gold nanoparticles (AuNPs). Compared with the currently available glucose kit method, the AuNP-based assay provides higher clinical sensitivity at lower cost, indicating its great potential to be a powerful tool for clinical screening of glucose. Electronic supplementary information (ESI) available: Experimental section and additional figures. See DOI: 10.1039/c5nr03758a

  12. Effects of high hydrostatic pressure or hydrophobic modification on thermal stability of xanthine oxidase.

    Science.gov (United States)

    Halalipour, Ali; Duff, Michael R; Howell, Elizabeth E; Reyes-De-Corcuera, José I

    2017-08-01

    The effect of high hydrostatic pressure (HHP) on the kinetics of thermal inactivation of xanthine oxidase (XOx) from bovine milk was studied. Inactivation of XOx followed pseudo-first-order kinetics at 0.1-300MPa and 55.0-70.0°C. High pressure up to at least 300MPa stabilized XOx at all the studied temperatures. The highest stabilization effect of HHP on XOx was at 200-300MPa at 55.0 and 58.6°C, and at 250-300MPa at 62.3-70.0°C. The stability of XOx increased 9.5 times at 300MPa and 70.0°C compared to atmospheric pressure at the same temperature. The activation energy of inactivation of XOx decreased with pressure and was 1.9 times less at 300MPa (97.0±8.2kJmol -1 ) than at 0.1MPa (181.7±12.1kJmol -1 ). High pressure decreased the dependence of the rate constant of inactivation to temperature effects compared to atmospheric pressure. The stabilizing effect of HHP on XOx was highest at 70.0°C where the activation volume of inactivation of XOx was 28.9±2.9cm 3 mol -1 . A second approach to try to increase XOx stability involved hydrophobic modification using aniline or benzoate. However, the thermal stability of XOx remained unaffected after 8-14 modifications of carboxyl side groups per XOx monomer with aniline, or 12-17 modifications of amino side groups per XOx monomer with benzoate. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. A new procedure for the purification of monodisperse highly active cytochrome c oxidase from bovine heart.

    OpenAIRE

    Li, Y; Naqui, A; Frey, T G; Chance, B

    1987-01-01

    A simple and rapid method for the isolation of a large quantity of cytochrome c oxidase from bovine heart mitochondria was developed, based on selective solubilization of mitochondrial protein with first Triton and then lauryl maltoside. Gel filtration shows that the lauryl maltoside-solubilized oxidase preparation is in a hydrodynamically homogeneous state with a Stokes radius of 7.5 +/- 0.2 nm. It contains 8.0 mumol of haem (with an a/a3 ratio of 1)/g of protein. The catalytic constant (max...

  14. Downregulation of Lysyl Oxidase Protects Retinal Endothelial Cells From High Glucose-Induced Apoptosis.

    Science.gov (United States)

    Kim, Dongjoon; Mecham, Robert P; Trackman, Philip C; Roy, Sayon

    2017-05-01

    To investigate the effect of reducing high glucose (HG)-induced lysyl oxidase (LOX) overexpression and increased activity on retinal endothelial cell apoptosis. Rat retinal endothelial cells (RRECs) were grown in normal (N) or HG (30 mM glucose) medium for 7 days. In parallel, RRECs were grown in HG medium and transfected with LOX small interfering RNA (siRNA), scrambled siRNA as control, or exposed to β-aminopropionitrile (BAPN), a LOX inhibitor. LOX expression, AKT activation, and caspase-3 activity were determined by Western blot (WB) analysis and apoptosis by differential dye staining assay. Moreover, to determine whether diabetes-induced LOX overexpression alters AKT activation and promotes apoptosis, changes in LOX expression, AKT phosphorylation, caspase-3 activation, and Bax expression were assessed in retinas of streptozotocin (STZ)-induced diabetic mice and LOX heterozygous knockout (LOX+/-) mice. WB analysis indicated significant LOX overexpression and reduced AKT activation under HG condition in RRECs. Interestingly, when cells grown in HG were transfected with LOX siRNA or exposed to BAPN, the number of apoptotic cells was significantly decreased concomitant with increased AKT phosphorylation. Diabetic mouse retinas exhibited LOX overexpression, decreased AKT phosphorylation, and increased Bax and caspase-3 activation compared to values in nondiabetic mice. In LOX+/- mice, reduced LOX levels were observed with increased AKT activity, and reduced Bax and caspase-3 activity. Furthermore, decreased levels of LOX in the LOX+/- mice was protective against diabetes-induced apoptosis. Findings from this study indicate that preventing LOX overexpression may be protective against HG-induced apoptosis in retinal vascular cells associated with diabetic retinopathy.

  15. Glucose oxidase stabilization against thermal inactivation using high hydrostatic pressure and hydrophobic modification.

    Science.gov (United States)

    Halalipour, Ali; Duff, Michael R; Howell, Elizabeth E; Reyes-De-Corcuera, José I

    2017-03-01

    High hydrostatic pressure (HHP) stabilized glucose oxidase (GOx) against thermal inactivation. The apparent first-order kinetics of inactivation of GOx were investigated at 0.1-300 MPa and 58.8-80.0°C. At 240 MPa and 74.5°C, GOx inactivated at a rate 50 times slower than at atmospheric pressure at the same temperature. The apparent activation energy of inactivation at 300 MPa was 281.0 ± 17.4 kJ mol -1 or 1.3-fold smaller than for the inactivation at atmospheric pressure (378.1 ± 25.6 kJ mol -1 ). The stabilizing effect of HHP was greatest at 74.5°C, where the activation volume of 57.0 ± 12.0 cm 3  mol -1 was highest compared to all other studied temperatures. Positive apparent activation volumes for all the treatment temperatures confirmed that HHP favors GOx stabilization. A second approach to increase GOx stability involved crosslinking with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and either aniline or benzoate. The modified enzyme remained fully active with only slight increases in K M (1.3-1.9-fold increases for aniline and benzoate modification, respectively). The thermal stability of GOx increased by 8°C with aniline modification, while it decreased by 0.9°C upon modification with benzoate. Biotechnol. Bioeng. 2017;114: 516-525. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  16. Plasmon-induced selective carbon dioxide conversion on earth-abundant aluminum-cuprous oxide antenna-reactor nanoparticles.

    Science.gov (United States)

    Robatjazi, Hossein; Zhao, Hangqi; Swearer, Dayne F; Hogan, Nathaniel J; Zhou, Linan; Alabastri, Alessandro; McClain, Michael J; Nordlander, Peter; Halas, Naomi J

    2017-06-21

    The rational combination of plasmonic nanoantennas with active transition metal-based catalysts, known as 'antenna-reactor' nanostructures, holds promise to expand the scope of chemical reactions possible with plasmonic photocatalysis. Here, we report earth-abundant embedded aluminum in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions. Through rigorous comparison of the spatial temperature profile, optical absorption, and integrated electric field enhancement of the catalyst, we have been able to distinguish between competing photothermal and hot-carrier driven mechanistic pathways. The antenna-reactor geometry efficiently harnesses the plasmon resonance of aluminum to supply energetic hot-carriers and increases optical absorption in cuprous oxide for selective carbon dioxide conversion to carbon monoxide with visible light. The transition from noble metals to aluminum based antenna-reactor heterostructures in plasmonic photocatalysis provides a sustainable route to high-value chemicals and reaffirms the practical potential of plasmon-mediated chemical transformations.Plasmon-enhanced photocatalysis holds promise for the control of chemical reactions. Here the authors report an Al@Cu 2 O heterostructure based on earth abundant materials to transform CO 2 into CO at significantly milder conditions.

  17. A Cuprous Oxide Thin Film Non-Enzymatic Glucose Sensor Using Differential Pulse Voltammetry and Other Voltammetry Methods and a Comparison to Different Thin Film Electrodes on the Detection of Glucose in an Alkaline Solution

    Directory of Open Access Journals (Sweden)

    Yifan Dai

    2018-01-01

    Full Text Available A cuprous oxide (Cu2O thin layer served as the base for a non-enzymatic glucose sensor in an alkaline medium, 0.1 NaOH solution, with a linear range of 50–200 mg/dL using differential pulse voltammetry (DPV measurement. An X-ray photoelectron spectroscopy (XPS study confirmed the formation of the cuprous oxide layer on the thin gold film sensor prototype. Quantitative detection of glucose in both phosphate-buffered saline (PBS and undiluted human serum was carried out. Neither ascorbic acid nor uric acid, even at a relatively high concentration level (100 mg/dL in serum, interfered with the glucose detection, demonstrating the excellent selectivity of this non-enzymatic cuprous oxide thin layer-based glucose sensor. Chronoamperometry and single potential amperometric voltammetry were used to verify the measurements obtained by DPV, and the positive results validated that the detection of glucose in a 0.1 M NaOH alkaline medium by DPV measurement was effective. Nickel, platinum, and copper are commonly used metals for non-enzymatic glucose detection. The performance of these metal-based sensors for glucose detection using DPV were also evaluated. The cuprous oxide (Cu2O thin layer-based sensor showed the best sensitivity for glucose detection among the sensors evaluated.

  18. Cuprous oxide nanoparticles selectively induce apoptosis of tumor cells

    Directory of Open Access Journals (Sweden)

    Wang Y

    2012-05-01

    Full Text Available Ye Wang,1,2,* Xiao-Yuan Zi,1,* Juan Su,1 Hong-Xia Zhang,1 Xin-Rong Zhang,3 Hai-Ying Zhu,1 Jian-Xiu Li,1 Meng Yin,3 Feng Yang,3 Yi-Ping Hu,11Department of Cell Biology, 2School of Clinical Medicine, 3Department of Pharmaceuticals, Second Military Medical University, Shanghai, People's Republic of China*Authors contributed equally.Abstract: In the rapid development of nanoscience and nanotechnology, many researchers have discovered that metal oxide nanoparticles have very useful pharmacological effects. Cuprous oxide nanoparticles (CONPs can selectively induce apoptosis and suppress the proliferation of tumor cells, showing great potential as a clinical cancer therapy. Treatment with CONPs caused a G1/G0 cell cycle arrest in tumor cells. Furthermore, CONPs enclosed in vesicles entered, or were taken up by mitochondria, which damaged their membranes, thereby inducing apoptosis. CONPs can also produce reactive oxygen species (ROS and initiate lipid peroxidation of the liposomal membrane, thereby regulating many signaling pathways and influencing the vital movements of cells. Our results demonstrate that CONPs have selective cytotoxicity towards tumor cells, and indicate that CONPs might be a potential nanomedicine for cancer therapy.Keywords: nanomedicine, selective cytotoxicity, apoptosis, cell cycle arrest, mitochondrion-targeted nanomaterials

  19. NiCoBP-doped carbon nanotube hybrid: A novel oxidase mimetic system for highly efficient electrochemical immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bing; He, Yu; Liu, Bingqian; Tang, Dianping, E-mail: dianping.tang@fzu.edu.cn

    2014-12-03

    Highlights: • We report a new oxidase mimetic system for highly efficient electrochemical immunoassay. • NiCoBP-doped carbon nanotube hybrids were used as the nanocatalysts. • NiCoBP-doped carbon nanotube hybrids were used as the mimic oxidase. - Abstract: NiCoBP-doped multi-walled carbon nanotube (NiCoBP–MWCNT) was first synthesized by using induced electroless-plating method and functionalized with the biomolecules for highly efficient electrochemical immunoassay of prostate-specific antigen (PSA, used as a model analyte). We discovered that the as-synthesized NiCoBP–MWCNT had the ability to catalyze the glucose oxidization with a stable and well-defined redox peak. The catalytic current increased with the increment of the immobilized NiCoBP–MWCNT on the electrode. Transmission electron microscope (TEM) and energy dispersive X-ray spectrometry (EDX) were employed to characterize the as-prepared NiCoBP–MWCNT. Using the NiCoBP–MWCNT-conjugated anti-PSA antibody as the signal-transduction tag, a new enzyme-free electrochemical immunoassay protocol could be designed for the detection of target PSA on the capture antibody-functionalized immunosensing interface. Experimental results revealed that the designed immunoassay system could exhibit good electrochemical responses toward target PSA, and allowed the detection of PSA at a concentration as low as 0.035 ng mL{sup −1}. More importantly, the NiCoBP-MWCNT-based oxidase mimetic system could be further extended for the monitoring of other low-abundance proteins or disease-related biomarkers by tuning the target antibody.

  20. Preparing cuprous oxide nanomaterials by electrochemical method for non-enzymatic glucose biosensor

    Science.gov (United States)

    Nguyen, Thu-Thuy; Huy, Bui The; Hwang, Seo-Young; Vuong, Nguyen Minh; Pham, Quoc-Thai; Nghia, Nguyen Ngoc; Kirtland, Aaron; Lee, Yong-Ill

    2018-05-01

    Cuprous oxide (Cu2O) nanostructure has been synthesized using an electrochemical method with a two-electrode system. Cu foils were used as electrodes and NH2(OH) was utilized as the reducing agent. The effects of pH and applied voltages on the morphology of the product were investigated. The morphology and optical properties of Cu2O particles were characterized using scanning electron microscopy, x-ray diffraction, and diffuse reflectance spectra. The synthesized Cu2O nanostructures that formed in the vicinity of the anode at 2 V and pH = 11 showed high uniform distribution, small size, and good electrochemical sensing. These Cu2O nanoparticles were coated on an Indium tin oxide substrate and applied to detect non-enzyme glucose as excellent biosensors. The non-enzyme glucose biosensors exhibited good performance with high response, good selectivity, wide linear detection range, and a low detection limit at 0.4 μM. Synthesized Cu2O nanostructures are potential materials for a non-enzyme glucose biosensor.

  1. TtMCO: A highly thermostable laccase-like multicopper oxidase from the thermophilic Thermobaculum terrenum

    DEFF Research Database (Denmark)

    Brander, Søren; Mikkelsen, Jørn Dalgaard; Kepp, Kasper Planeta

    2015-01-01

    This paper reports the identification, heterologous expression in Escherichia coli and characterization of TtMCO from the thermophilic bacterium Thermobaculum terrenum, the first laccase-like multi-copper oxidase (LMCO) from the distinct Phylum Chloroflexi. TtMCO has only 39% identity to its...... closest characterized homologue, CotA from Bacillus subtilis, but sequence and spectrophotometry confirmed copper coordination similar to that of LMCOs. TtMCO is extremely thermophilic with a half-time of inactivation of 2.24 days at 70 degrees C and 350 min at 80°C and pH 7, consistent...

  2. Stability of sputter deposited cuprous oxide (Cu2O) subjected to ageing conditions for photovoltaic applications

    Science.gov (United States)

    Camacho-Espinosa, E.; Rimmaudo, I.; Riech, I.; Mis-Fernández, R.; Peña, J. L.

    2018-02-01

    Among various metal oxide p-type semiconductors, cuprous oxide (Cu2O) stands out as a nontoxic and abundant material, which also makes it a suitable candidate as a low-cost absorber for photovoltaic applications. However, the chemical stability of the absorber layer is critical for the solar cell lifetime, in particular, for Cu-based materials, concerning to its oxidation state changes. In this paper, we addressed the Cu2O stability depositing films of 170 nm by reactive radio frequency magnetron sputtering and subsequently ageing them in conditions similar to the typical accelerated life test for the solar module, in a period of time from one to five weeks. The stability of the optical, electrical, and structural properties of the Cu2O thin films was investigated using UV-VIS-near infrared transmittance, 4-probes electrical resistance characterization, high precision profilometry, X-ray photoelectron spectroscopy, and grazing incidence X-ray diffraction. Finally, we demonstrated that the aging tests affected only the surface of the films, while the bulk remained unaltered, making Cu2O a promising candidate for production of stable devices, including solar cells.

  3. Activation of persulfate/copper by hydroxylamine via accelerating the cupric/cuprous redox couple.

    Science.gov (United States)

    Zhou, Peng; Zhang, Jing; Liang, Juan; Zhang, Yongli; Liu, Ya; Liu, Bei

    2016-01-01

    Cuprous copper [Cu(I)] reacts with sodium persulfate (PDS) to generate sulfate radical SO4(-)•, but it has been seldom investigated owing to its instability and difficulty in dissolving it. This study proposes a new method to regenerate Cu(I) from cupric copper [Cu(II)] by addition of hydroxylamine (HA) to induce the continuous production of radicals through active PDS, and investigates the resulting enhanced methyl orange (MO) degradation efficiency and mechanism in the new system. HA accelerated the degradation of MO markedly in the pH range from 6.0 to 8.0 in the HA/Cu(II)/PDS process. Both SO4(-)• and hydroxyl radicals (•OH) were considered as the primary reactive radicals in the process. The MO degradation in the HA/Cu(II)/PDS process can be divided into three stages: the fast stage, the transitory stage, and the low stage. MO degradation was enhanced with increased dosage of PDS. Although high dosage of HA could accelerate the transformation of the Cu(II)/Cu(I) cycle to produce more reactive radicals, excess HA can quench the reactive radicals. This study indicates that through a copper-redox cycling mechanism by HA, the production of SO4(-)• and •OH can be strongly enhanced, and the effective pH range can be expanded to neutral conditions.

  4. High resolution structure of the ba3 cytochrome c oxidase from Thermus thermophilus in a lipidic environment.

    Directory of Open Access Journals (Sweden)

    Theresa Tiefenbrunn

    Full Text Available The fundamental chemistry underpinning aerobic life on Earth involves reduction of dioxygen to water with concomitant proton translocation. This process is catalyzed by members of the heme-copper oxidase (HCO superfamily. Despite the availability of crystal structures for all types of HCO, the mode of action for this enzyme is not understood at the atomic level, namely how vectorial H(+ and e(- transport are coupled. Toward addressing this problem, we report wild type and A120F mutant structures of the ba(3-type cytochrome c oxidase from Thermus thermophilus at 1.8 Å resolution. The enzyme has been crystallized from the lipidic cubic phase, which mimics the biological membrane environment. The structures reveal 20 ordered lipid molecules that occupy binding sites on the protein surface or mediate crystal packing interfaces. The interior of the protein encloses 53 water molecules, including 3 trapped in the designated K-path of proton transfer and 8 in a cluster seen also in A-type enzymes that likely functions in egress of product water and proton translocation. The hydrophobic O(2-uptake channel, connecting the active site to the lipid bilayer, contains a single water molecule nearest the Cu(B atom but otherwise exhibits no residual electron density. The active site contains strong electron density for a pair of bonded atoms bridging the heme Fe(a3 and Cu(B atoms that is best modeled as peroxide. The structure of ba(3-oxidase reveals new information about the positioning of the enzyme within the membrane and the nature of its interactions with lipid molecules. The atomic resolution details provide insight into the mechanisms of electron transfer, oxygen diffusion into the active site, reduction of oxygen to water, and pumping of protons across the membrane. The development of a robust system for production of ba(3-oxidase crystals diffracting to high resolution, together with an established expression system for generating mutants, opens the

  5. The use of cuprous iodide as a precipitation matrix in the radiochemical determination of 131I in milk

    International Nuclear Information System (INIS)

    McCurdy, D.E.; Mellor, R.A.; Lambdin, R.W.; McLain, M.E. Jr.

    1980-01-01

    As a result of the implementation of the As Low As is Reasonably Achievable philosophy to the nuclear power industry, recent U.S. Nuclear Regulatory Commission requirements have prompted high sensitivity radiochemical analysis for the measurement of 131 I in milk. The most recognized and commonly employed technique incorporates costly palladium iodide as the final precipitate in the radiochemical purification of the iodine chemical species. The procedure presented in this paper outlines the many advantages of using cuprous iodide as the final precipitate. These include lower cost per analysis, consistent recoveries, better precipitate matrix and good self absorption characteristics. Typical lower limit of detection values and operating characteristics obtained for high sensitivity β-γ analysis as well as gas proportional counting and a comparison of radiochemical and Ge(Li) spectrometric results for environmental samples collected during a recent Chinese weapons fallout incident are presented. (author)

  6. Metformin and liraglutide ameliorate high glucose-induced oxidative stress via inhibition of PKC-NAD(P)H oxidase pathway in human aortic endothelial cells.

    Science.gov (United States)

    Batchuluun, Battsetseg; Inoguchi, Toyoshi; Sonoda, Noriyuki; Sasaki, Shuji; Inoue, Tomoaki; Fujimura, Yoshinori; Miura, Daisuke; Takayanagi, Ryoichi

    2014-01-01

    Metformin and glucagon like peptide-1 (GLP-1) prevent diabetic cardiovascular complications and atherosclerosis. However, the direct effects on hyperglycemia-induced oxidative stress in endothelial cells are not fully understood. Thus, we aimed to evaluate the effects of metformin and a GLP-1 analog, liraglutide on high glucose-induced oxidative stress. Production of reactive oxygen species (ROS), activation of protein kinase C (PKC) and NAD(P)H oxidase, and changes in signaling molecules in response to high glucose exposure were evaluated in human aortic endothelial cells with and without treatment of metformin and liraglutide, alone or in combination. PKC-NAD(P)H oxidase pathway was assessed by translocation of GFP-fused PKCβ2 isoform and GFP-fused p47phox, a regulatory subunit of NAD(P)H oxidase, in addition to endogenous PKC phosphorylation and NAD(P)H oxidase activity. High glucose-induced ROS overproduction was blunted by metformin or liraglutide treatment, with a further decrease by a combination of these drugs. Exposure to high glucose caused PKCβ2 translocation and a time-dependent phosphorylation of endogenous PKC but failed to induce its translocation and phosphorylation in the cells treated with metformin and liraglutide. Furthermore, both drugs inhibited p47phox translocation and NAD(P)H oxidase activation, and prevented the high glucose-induced changes in intracellulalr diacylglycerol (DAG) level and phosphorylation of AMP-activated protein kinase (AMPK). A combination of these drugs further enhanced all of these effects. Metformin and liraglutide ameliorate high glucose-induced oxidative stress by inhibiting PKC-NAD(P)H oxidase pathway. A combination of these two drugs provides augmented protective effects, suggesting the clinical usefulness in prevention of diabetic vascular complications. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  7. Cuprous oxide nanoparticles dispersed on reduced graphene oxide as an efficient electrocatalyst for oxygen reduction reaction.

    Science.gov (United States)

    Yan, Xiao-Yan; Tong, Xi-Li; Zhang, Yue-Fei; Han, Xiao-Dong; Wang, Ying-Yong; Jin, Guo-Qiang; Qin, Yong; Guo, Xiang-Yun

    2012-02-11

    Cuprous oxide (Cu(2)O) nanoparticles dispersed on reduced graphene oxide (RGO) were prepared by reducing copper acetate supported on graphite oxide using diethylene glycol as both solvent and reducing agent. The Cu(2)O/RGO composite exhibits excellent catalytic activity and remarkable tolerance to methanol and CO in the oxygen reduction reaction. This journal is © The Royal Society of Chemistry 2012

  8. Biophysical and physicochemical methods differentiate highly ligand-efficient human D-amino acid oxidase inhibitors.

    Science.gov (United States)

    Lange, Jos H M; Venhorst, Jennifer; van Dongen, Maria J P; Frankena, Jurjen; Bassissi, Firas; de Bruin, Natasja M W J; den Besten, Cathaline; de Beer, Stephanie B A; Oostenbrink, Chris; Markova, Natalia; Kruse, Chris G

    2011-10-01

    Many early drug research efforts are too reductionist thereby not delivering key parameters such as kinetics and thermodynamics of target-ligand binding. A set of human D-Amino Acid Oxidase (DAAO) inhibitors 1-6 was applied to demonstrate the impact of key biophysical techniques and physicochemical methods in the differentiation of chemical entities that cannot be adequately distinguished on the basis of their normalized potency (ligand efficiency) values. The resulting biophysical and physicochemical data were related to relevant pharmacodynamic and pharmacokinetic properties. Surface Plasmon Resonance data indicated prolonged target-ligand residence times for 5 and 6 as compared to 1-4, based on the observed k(off) values. The Isothermal Titration Calorimetry-derived thermodynamic binding profiles of 1-6 to the DAAO enzyme revealed favorable contributions of both ΔH and ΔS to their ΔG values. Surprisingly, the thermodynamic binding profile of 3 elicited a substantially higher favorable contribution of ΔH to ΔG in comparison with the structurally closely related fused bicyclic acid 4. Molecular dynamics simulations and free energy calculations of 1, 3, and 4 led to novel insights into the thermodynamic properties of the binding process at an atomic level and in the different thermodynamic signatures of 3 and 4. The presented holistic approach is anticipated to facilitate the identification of compounds with best-in-class properties at an early research stage. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  9. Millimeter- and submillimeter-wave spectrum and molecular constants of cuprous iodide

    International Nuclear Information System (INIS)

    Manson, E.L.; De Lucia, F.C.; Gordy, W.

    1975-01-01

    Monomeric cuprous iodide (CuI) in the vapor state has been produced as an intermediate product of the reaction of copper with iodine vapor at 1100 degreeK in a quasi-free-space microwave absorption cell. Rotational transitions of 63 Cu 127 I and 65 Cu 127 I were measured for J as high as 87→88 and for ν as high as 11. Hyperfine splittings due to 127 I were observed, and eqQ ( 127 I) =-935(15) MHz was derived. Analysis of the rotational frequencies yields the following Dunham and equilibrium coefficients for 63 Cu 127 I: Y 01 =2197.10172(98) MHz, Y 11 =-8.51120(66) MHz, Y 21 =0.00934(14) MHz, Y 31 =-0.0375(88) kHz, Y 02 =-0.67269(10) kHz, Y 12 =0.031(34) Hz, Y 03 =-0.00006858(10) Hz, B/sube/=2197.102(2) MHz, ω/sube/=264.897(18) cm -1 , ω/sube/chi/sube/=0.715(2) cm -1 , r/sube/=2.33831686(104) A; for 65 Cu 127 I: Y 01 =2151.89989(94) MHz, Y 11 =-8.24990(66) MHz, Y 21 =0.00896(14) MHz, Y 31 =-0.0356(88) kHz, Y 02 =-0.64530(10) kHz, Y 12 =0.030(34) Hz, Y 03 =-0.00006443(10) Hz, B/sube/=2151.900(2) MHz, ω/sube/=262.157(18) cm -1 , ω/sube/chi/sube/=0.700(2) cm -1 , r/sube/=2.33831664(102) A. The Dunham potential constants for CuI are a 0 =239 366(34) cm -1 , a 1 =-3.33365(36), a 2 =7.391(16), and a 3 =-13.20(18)

  10. Hierarchical CNFs/MnCo2O4.5 nanofibers as a highly active oxidase mimetic and its application in biosensing

    Science.gov (United States)

    Gao, Mu; Lu, Xiaofeng; Nie, Guangdi; Chi, Maoqiang; Wang, Ce

    2017-12-01

    Recently, much attention has been paid on the nanomaterial-based artificial enzymes due to their tunable catalytic activity, high stability and low cost compared to the natural enzymes. Different from the peroxidase mimics which have been studied for several decades, nanomaterials with oxidase-like property are burgeoning in the recent years. In this paper, hierarchical carbon nanofibers (CNFs)/MnCo2O4.5 nanofibers as efficient oxidase mimics are reported. The products are synthesized by an electrospinning technique and an electrochemcial deposition process in which the CNFs are used as the working electrode where MnCo2O4.5 nanosheets deposit on. The resulting binary metal oxide-based nanocomposites exhibit a good oxidase-like activity toward the oxidations of 3,3‧,5,5‧tetramethylbenzi-dine (TMB), 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) salt and o-phenylenediamine (OPD) without exogenous addition of H2O2. The system of CNFs/MnCo2O4.5-TMB can be used as a candidate to detect sulfite and ascorbic acid via a colorimetric method with a high sensitivity. This work provides the efficient utilization and potential applications of binary metal oxide-based nanocomposites with oxidase activities in biosensors and other biotechnologies.

  11. Integration of a highly ordered gold nanowires array with glucose oxidase for ultra-sensitive glucose detection.

    Science.gov (United States)

    Cui, Jiewu; Adeloju, Samuel B; Wu, Yucheng

    2014-01-27

    A highly sensitive amperometric nanobiosensor has been developed by integration of glucose oxidase (GO(x)) with a gold nanowires array (AuNWA) by cross-linking with a mixture of glutaraldehyde (GLA) and bovine serum albumin (BSA). An initial investigation of the morphology of the synthesized AuNWA by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) revealed that the nanowires array was highly ordered with rough surface, and the electrochemical features of the AuNWA with/without modification were also investigated. The integrated AuNWA-BSA-GLA-GO(x) nanobiosensor with Nafion membrane gave a very high sensitivity of 298.2 μA cm(-2) mM(-1) for amperometric detection of glucose, while also achieving a low detection limit of 0.1 μM, and a wide linear range of 5-6000 μM. Furthermore, the nanobiosensor exhibited excellent anti-interference ability towards uric acid (UA) and ascorbic acid (AA) with the aid of Nafion membrane, and the results obtained for the analysis of human blood serum indicated that the device is capable of glucose detection in real samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Correlated lifetimes of free paraexcitons and excitons trapped at oxygen vacancies in cuprous oxide

    International Nuclear Information System (INIS)

    Koirala, Sandhaya; Naka, Nobuko; Tanaka, Koichiro

    2013-01-01

    We have studied transients of luminescence due to free excitons and excitons trapped at oxygen vacancies in cuprous oxide. We find that both trapped and free paraexcitons have lifetime dependent on temperature and on the oxygen concentration. By using samples containing much less copper vacancies relative to oxygen vacancies, we find out the direct correlation between the free paraexciton lifetime and trapped exciton lifetime. - Highlights: ► We have investigated trapping of free excitons at oxygen vacancies in cuprous oxide. ► Lifetimes of free and trapped excitons exhibit correlative temperature dependence. ► Four-level model with the activation energy of 33 meV well explains the observation. ► Comparison is made using the four samples with different vacancy concentrations. ► We clarified the crucial role of the oxygen vacancy in shortening the lifetimes.

  13. High-content screening of Aspergillus niger with both increased production and high secretion rate of glucose oxidase.

    Science.gov (United States)

    Zhu, Xudong; Sun, Jingchun; Chu, Ju

    2018-01-01

    To develop a rapid, dual-parameter, plate-based screening process to improve production and secretion rate of glucose oxidase simultaneously in Aspergillus niger. A morphology engineering based on CaCO 3 was implemented, where the yield of GOD by A. niger was increased by up to 50%. Analysis of extracellular GOD activity was achieved in 96-well plates. There was a close negative correlation between the total GOD activity and its residual glucose of the fermentation broth. Based on this, a rapid, plate-based, qualitative analysis method of the total GOD activity was developed. Compared with the conventional analysis method using o-dianisidine, a correlation coefficient of -0.92 by statistical analysis was obtained. Using this dual-parameter screening method, we acquired a strain with GOD activity of 3126 U l -1 , which was 146% higher than the original strain. Its secretion rate of GOD was 83, 32% higher than the original strain.

  14. Light-Induced Reduction of Cuprous Oxide in an Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Cavalca, Filippo Carlo; Laursen, Anders Bo; Wagner, Jakob Birkedal

    2013-01-01

    Photocatalysts for solar fuel production are subject to intensive investigation as they constitute one viable route for solar energy harvesting. Cuprous oxide (Cu2O) is a working photocatalyst for hydrogen evolution but it photocorrodes upon light illumination in an aqueous environment....... Environmental transmission electron microscopy (ETEM) makes it possible to obtain insight into the local structure, composition and reactivity of catalysts in their working environment, which is of fundamental interest for sustainable energy research and is essential for further material optimization. Herein...

  15. Synthesis of cuprous oxide epoxy nanocomposite as an environmentally antimicrobial coating.

    Science.gov (United States)

    M El Saeed, Ashraf; Abd El-Fattah, M; Azzam, Ahmed M; Dardir, M M; Bader, Magd M

    2016-08-01

    Cuprous oxide is commonly used as a pigment; paint manufacturers begin to employ cuprous oxide as booster biocides in their formulations, to replace the banned organotins as the principal antifouling compounds. Epoxy coating was reinforced with cuprous oxide nanoparticles (Cu2O NPs). The antibacterial as well as antifungal activity of Cu2O epoxy nanocomposite (Cu2O EN) coating films was investigated. Cu2O NPs were also experimented for antibiofilm and time-kill assay. The thermal stability and the mechanical properties of Cu2O EN coating films were also investigated. The antimicrobial activity results showed slowdown, the growth of organisms on the Cu2O EN coating surface. TGA results showed that incorporating Cu2O NPs into epoxy coating considerably enhanced the thermal stability and increased the char residue. The addition of Cu2O NPs at lower concentration into epoxy coating also led to an improvement in the mechanical resistance such as scratch and abrasion. Cu2O NPs purity was confirmed by XRD. The TEM photograph demonstrated that the synthesized Cu2O NPs were of cubic shape and the average diameter of the crystals was around 25nm. The resulting perfect dispersion of Cu2O NPs in epoxy coating revealed by SEM ensured white particles embedded in the epoxy matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Astragaloside IV prevents damage to human mesangial cells through the inhibition of the NADPH oxidase/ROS/Akt/NF‑κB pathway under high glucose conditions.

    Science.gov (United States)

    Sun, Li; Li, Weiping; Li, Weizu; Xiong, Li; Li, Guiping; Ma, Rong

    2014-07-01

    Glomerular hypertrophy and hyperfiltration are the two major pathological characteristics of the early stages of diabetic nephropathy (DN), which are respectively related to mesangial cell (MC) proliferation and a decrease in calcium influx conducted by canonical transient receptor potential cation channel 6 (TRPC6). The marked increase in the production of reactive oxygen species (ROS) induced by hyperglycemia is the main sponsor of multiple pathological pathways in DN. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is an important source of ROS production in MCs. Astragaloside IV (AS‑IV) is an active ingredient of Radix Astragali which has a potent antioxidative effect. In this study, we aimed to investigate whether high glucose (HG)‑induced NADPH oxidase activation and ROS production contribute to MC proliferation and the downregulation of TRPC6 expression; we also wished to determine the effects of AS‑IV on MCs under HG conditions. Using a human glomerular mesangial cell line, we found that treatment with AS‑IV for 48 h markedly attenuated HG‑induced proliferation and the hypertrophy of MCs in a dose‑dependent manner. The intracellular ROS level was also markedly reduced following treatment with AS‑IV. In addition, the enhanced activity of NADPH oxidase and the expression level of NADPH oxidase 4 (Nox4) protein were decreased. Treatment with AS‑IV also inhibited the phosphorylation level of Akt and IκBα in the MCs. In addition, TRPC6 protein expression and the intracellular free calcium concentration were also markedly reduced following treatment with AS‑IV under HG conditions. These results suggest that AS‑IV inhibits HG‑induced mesangial cell proliferation and glomerular contractile dysfunction through the NADPH oxidase/ROS/Akt/nuclear factor‑κB (NF‑κB) pathway, providing a new perspective for the clinical treatment of DN.

  17. Resveratrol prevents high glucose-induced epithelial-mesenchymal transition in renal tubular epithelial cells by inhibiting NADPH oxidase/ROS/ERK pathway.

    Science.gov (United States)

    He, Ting; Guan, Xu; Wang, Song; Xiao, Tangli; Yang, Ke; Xu, Xinli; Wang, Junping; Zhao, Jinghong

    2015-02-15

    Resveratrol (RSV) is reported to have renoprotective activity against diabetic nephropathy, while the mechanisms underlying its function have not been fully elucidated. In this study, we investigate the effect and related mechanism of RSV against high glucose-induced epithelial to mesenchymal transition (EMT) in human tubular epithelial cells (HK-2). A typical EMT is induced by high glucose in HK-2 cells, accompanied by increased levels of reactive oxygen species (ROS). RSV exhibits a strong ability to inhibit high glucose-induced EMT by decreasing intracellular ROS levels via down-regulation of NADPH oxidase subunits NOX1 and NOX4. The activation of extracellular signal-regulated kinase (ERK1/2) is found to be involved in high glucose-induced EMT in HK-2 cells. RSV, like NADPH oxidase inhibitor diphenyleneiodonium, can block ERK1/2 activation induced by high glucose. Our results demonstrate that RSV is a potent agent against high glucose-induced EMT in renal tubular cells via inhibition of NADPH oxidase/ROS/ERK1/2 pathway. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  18. Integration of a highly ordered gold nanowires array with glucose oxidase for ultra-sensitive glucose detection

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jiewu [NanoScience and Sensor Technology Research Group, School of Applied Sciences and Engineering, Monash University, Gippsland Campus, Churchill 3842, VIC Australia (Australia); Laboratory of Functional Nanomaterials and Devices, School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, Anhui (China); Adeloju, Samuel B., E-mail: sam.adeloju@monash.edu [NanoScience and Sensor Technology Research Group, School of Applied Sciences and Engineering, Monash University, Gippsland Campus, Churchill 3842, VIC Australia (Australia); Wu, Yucheng, E-mail: ycwu@hfut.edu.cn [Laboratory of Functional Nanomaterials and Devices, School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, Anhui (China)

    2014-01-27

    Graphical abstract: -- Highlights: •Successfully synthesised highly-ordered gold nanowires array with an AAO template. •Fabricated an ultra-sensitive glucose nanobiosensor with the gold nanowires array. •Achieved sensitivity as high as 379.0 μA cm{sup −2} mM{sup −1} and detection limit as low as 50 nM. •Achieved excellent anti-interference with aid of Nafion membrane towards UA and AA. •Enabled successful detection and quantification of glucose in human blood serum. -- Abstract: A highly sensitive amperometric nanobiosensor has been developed by integration of glucose oxidase (GO{sub x}) with a gold nanowires array (AuNWA) by cross-linking with a mixture of glutaraldehyde (GLA) and bovine serum albumin (BSA). An initial investigation of the morphology of the synthesized AuNWA by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) revealed that the nanowires array was highly ordered with rough surface, and the electrochemical features of the AuNWA with/without modification were also investigated. The integrated AuNWA–BSA–GLA–GO{sub x} nanobiosensor with Nafion membrane gave a very high sensitivity of 298.2 μA cm{sup −2} mM{sup −1} for amperometric detection of glucose, while also achieving a low detection limit of 0.1 μM, and a wide linear range of 5–6000 μM. Furthermore, the nanobiosensor exhibited excellent anti-interference ability towards uric acid (UA) and ascorbic acid (AA) with the aid of Nafion membrane, and the results obtained for the analysis of human blood serum indicated that the device is capable of glucose detection in real samples.

  19. Differences in Monoamine Oxidase Activity in the Brain of Wistar and August Rats with High and Low Locomotor Activity: A Cytochemical Study.

    Science.gov (United States)

    Sergutina, A V; Rakhmanova, V I

    2016-06-01

    Monoamine oxidase activity was quantitatively assessed by cytochemical method in brain structures (layers III and V of the sensorimotor cortex, caudate nucleus, nucleus accumbens, hippocampal CA3 field) of rats of August line and Wistar population with high and low locomotor activity in the open fi eld test. Monoamine oxidase activity (substrate tryptamine) predominated in the nucleus accumbens of Wistar rats with high motor activity in comparison with rats with low locomotor activity. In August rats, enzyme activity (substrates tryptamine and serotonin) predominated in the hippocampus of animals with high motor activity. Comparison of August rats with low locomotor activity and Wistar rats with high motor activity (i.e. animals demonstrating maximum differences in motor function) revealed significantly higher activity of the enzyme (substrates tryptamine and serotonin) in the hippocampus of Wistar rats. The study demonstrates clear-cut morphochemical specificity of monoaminergic metabolism based on the differences in the cytochemical parameter "monoamine oxidase activity", in the studied brain structures, responsible for the formation and realization of goal-directed behavior in Wistar and August rats.

  20. Exciton-polaritons in cuprous oxide: Theory and comparison with experiment

    Science.gov (United States)

    Schweiner, Frank; Ertl, Jan; Main, Jörg; Wunner, Günter; Uihlein, Christoph

    2017-12-01

    The observation of giant Rydberg excitons in cuprous oxide (Cu2O ) up to a principal quantum number of n =25 by T. Kazimierczuk et al. [Nature (London) 514, 343 (2014), 10.1038/nature13832] inevitably raises the question whether these quasiparticles must be described within a multipolariton framework since excitons and photons are always coupled in the solid. In this paper we present the theory of exciton-polaritons in Cu2O . To this end we extend the Hamiltonian which includes the complete valence-band structure, the exchange interaction, and the central-cell corrections effects, and which has been recently deduced by F. Schweiner et al. [Phys. Rev. B 95, 195201 (2017), 10.1103/PhysRevB.95.195201], for finite values of the exciton momentum ℏ K . We derive formulas to calculate not only dipole but also quadrupole oscillator strengths when using the complete basis of F. Schweiner et al., which has recently been proven as a powerful tool to calculate exciton spectra. Very complex polariton spectra for the three orientations of K along the axes [001 ] , [110 ] , and [111 ] of high symmetry are obtained and a strong mixing of exciton states is reported. The main focus is on the 1 S ortho-exciton-polariton, for which pronounced polariton effects have been measured in experiments. We set up a 5 ×5 matrix model, which accounts for both the polariton effect and the K -dependent splitting, and which allows treating the anisotropic polariton dispersion for any direction of K . We especially discuss the dispersions for K being oriented in the planes perpendicular to [1 1 ¯0 ] and [111 ] , for which experimental transmission spectra have been measured. Furthermore, we compare our results with experimental values of the K -dependent splitting, the group velocity, and the oscillator strengths of this exciton-polariton. The results are in good agreement. This proves the validity of the 5 ×5 matrix model as a useful theoretical model for further investigations on the 1 S

  1. Vanillyl alcohol oxidases produced in Komagataella phaffii contain a highly stable non-covalently bound anionic FAD semiquinone

    NARCIS (Netherlands)

    Gygli, G.A.; Berkel, van W.J.H.

    2017-01-01

    Vanillyl alcohol oxidase (VAO) from Penicillium simplicissimum is a covalent flavoprotein that has emerged as a promising biocatalyst for the production of aromatic fine chemicals such as vanillin, coniferyl alcohol and enantiopure 1-(4’-hydroxyphenyl) alcohols. The largescale production of this

  2. Azure B, a metabolite of methylene blue, is a high-potency, reversible inhibitor of monoamine oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Petzer, Anél, E-mail: 12264954@nwu.ac.za [Unit for Drug Research and Development, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520 (South Africa); Harvey, Brian H. [Division of Pharmacology, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520 (South Africa); Wegener, Gregers [Centre for Psychiatric Research, Aarhus University Hospital-Risskov, Skovagervej 2, 8240 Risskov (Denmark); Petzer, Jacobus P. [Division of Pharmaceutical Chemistry, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520 (South Africa)

    2012-02-01

    Methylene blue (MB) has been shown to act at multiple cellular and molecular targets and as a result possesses diverse medical applications. Among these is a high potency reversible inhibition of monoamine oxidase A (MAO-A) that may, at least in part, underlie its adverse effects but also its psycho- and neuromodulatory actions. MB is metabolized to yield N-demethylated products of which azure B, the monodemethyl species, is the major metabolite. Similar to MB, azure B also displays a variety of biological activities and may therefore contribute to the pharmacological profile of MB. Based on these observations, the present study examines the interactions of azure B with recombinant human MAO-A and -B. The results show that azure B is a potent MAO-A inhibitor (IC{sub 50} = 11 nM), approximately 6-fold more potent than is MB (IC{sub 50} = 70 nM) under identical conditions. Measurements of the time-dependency of inhibition suggest that the interaction of azure B with MAO-A is reversible. Azure B also reversibly inhibits the MAO-B isozyme with an IC{sub 50} value of 968 nM. These results suggest that azure B may be a hitherto under recognized contributor to the pharmacology and toxicology of MB by blocking central and peripheral MAO-A activity and as such needs to be considered during its use in humans and animals. Highlights: ► Methylene blue (MB) is a known potent MAO-A inhibitor. ► Azure B, the major metabolite of MB, is more potent as a MAO-A inhibitor. ► Azure B may be a contributor to the CNS pharmacology and toxicology of MB.

  3. Facile synthesis of cuprous oxide nanowires decorated graphene oxide nanosheets nanocomposites and its application in label-free electrochemical immunosensor.

    Science.gov (United States)

    Wang, Huan; Zhang, Yong; Wang, Yulan; Ma, Hongmin; Du, Bin; Wei, Qin

    2017-01-15

    In this work, the assembly between one-dimensional (1D) nanomaterials and two-dimensional (2D) nanomaterials was achieved by a simple method. Cuprous oxide nanowires decorated graphene oxide nanosheets (Cu 2 O@GO) nanocomposites were synthesized for the first time by a simple electrostatic self-assembly process. The nanostructure was well confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM) images. Taking advantages of good electrocatalytic activity and high specific surface area of Cu 2 O@GO nanocomposites, a label-free electrochemical immunosensor was developed by employing Cu 2 O@GO as signal amplification platform for the quantitative detection of alpha fetoprotein (AFP). In addition, toluidine blue (TB) was used as the electron transfer mediator to provide the electrochemical signal, which was adsorbed on graphene oxide nanosheets (GO NSs) by electrostatic attraction. The detection mechanism was based on the monitoring of the electrochemical current response change of TB by the square wave voltammetry (SWV) when immunoreaction occurred on the surface of electrode. Under optimal conditions, the proposed immunosensor displayed a high sensitivity and a low detection limit. This designed method may provide an effective method in the clinical diagnosis of AFP and other tumor markers. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Exploring flavin-containing carbohydrate oxidases

    NARCIS (Netherlands)

    Ferrari, Alessandro Renato

    2017-01-01

    Oxidases are enzymes capable of removing one or more electrons from their substrate and transfer them to molecular oxygen, forming hydrogen peroxide. Due to their high regio- and enantioselectivity, their use is preferred over traditional organic chemistry methods. Among the oxidases, flavoprotein

  5. Towards printed perovskite solar cells with cuprous oxide hole transporting layers

    DEFF Research Database (Denmark)

    Wang, Yan; Xia, Zhonggao; Liang, Jun

    2015-01-01

    Solution-processed p-type metal oxide materials have shown great promise in improving the stability of perovskite-based solar cells and offering the feasibility for a low cost printing fabrication process. Herein, we performed a device modeling study on planar perovskite solar cells with cuprous...... oxide (Cu2O) hole transporting layers (HTLs) by using a solar cell simulation program, wxAMPS. The performance of a Cu2O/perovskite solar cell was correlated to the material properties of the Cu2O HTL, such as thickness, carrier mobility, mid-gap defect, and doping...

  6. Multicomponent exciton gas in cuprous oxide: cooling behaviour and the role of Auger decay

    Science.gov (United States)

    Semkat, D.; Sobkowiak, S.; Schöne, F.; Stolz, H.; Koch, Th; Fehske, H.

    2017-10-01

    In this paper we present a hydrodynamic model to describe the dynamics of para- and orthoexcitons in cuprous oxide at ultralow temperatures inside a stress induced potential trap. We take into account the finite lifetime of the excitons, the excitation process and exciton-phonon as well as exciton-exciton interaction. Furthermore, we model the two-body loss mechanism assuming an Auger-like effect and compare it to an alternative explanation which relies on the formation of biexcitons. We discuss in detail the influence on the numerical results and compare the predictions to experimental data.

  7. Protoporphyrinogen oxidase: high affinity tetrahydrophthalimide radioligand for the inhibitor/herbicide-binding site in mouse liver mitochondria.

    Science.gov (United States)

    Birchfield, N B; Casida, J E

    1996-01-01

    Protoporphyrinogen oxidase (protox), the last common enzyme in heme and chlorophyll biosynthesis, is the target of several classes of herbicides acting as inhibitors in both plants and mammals. N-(4-Chloro-2-fluoro-5-(propargyloxy)phenyl)-3,4,5,6-tetrahydro phthalimide (a potent protox inhibitor referred to as THP) was synthesized as a candidate radioligand ([3H]-THP) by selective catalytic reduction of 3,6-dihydrophthalic anhydride (DHPA) with tritium gas followed by condensation in 45% yield with 4-chloro-2-fluoro-5-(propargyloxy)aniline. Insertion of tritium at the 3 and 6 carbons of DHPA as well as the expected 4 and 5 carbons resulted in high specific activity [3H]THP (92 Ci/mmol). This radioligand undergoes rapid, specific, saturable, and reversible binding to the inhibitor/herbicide binding site of the protox component of cholate-solubilized mouse liver mitochondria with an apparent Kd of 0.41 nM and Bmax of 0.40 pmol/mg of protein. In the standard assay, mouse preparation (150 micrograms of protein) and [3H]THP (0.5 nM) are incubated in 500 microL of phosphate buffer at pH 7.2 for 15 min at 25 degrees C followed by addition of ammonium sulfate and filtration with glass fiber filters. The potencies of five nitrodiphenyl ethers and two other herbicides as inhibitors of [3H]THP binding correlate well with those for inhibition of protox activity (r2 = 0.97, n = 7), thus validating the binding assay as relevant to enzyme inhibition. It is also suitable to determine in vivo block as illustrated by an approximately 50% decrease in [3H]THP binding in liver mitochondria from mice treated ip with oxyfluorfen at 4 mg/kg. This is the first report of a binding assay for protox in mammals. The high affinity and specific activity of [3H]THP facilitate quantitation of protox and therefore research on a sensitive inhibition site for porphyrin biosynthesis.

  8. RXR agonists inhibit high glucose-induced upregulation of inflammation by suppressing activation of the NADPH oxidase-nuclear factor-κB pathway in human endothelial cells.

    Science.gov (United States)

    Ning, R B; Zhu, J; Chai, D J; Xu, C S; Xie, H; Lin, X Y; Zeng, J Z; Lin, J X

    2013-12-13

    An inflammatory response induced by high glucose is a cause of endothelial dysfunction in diabetes and is an important contributing link to atherosclerosis. Diabetes is an independent risk factor of atherosclerosis and activation of retinoid X receptor (RXR) has been shown to exert anti-atherogenic effects. In the present study, we examined the effects of the RXR ligands 9-cis-retinoic acid (9-cis-RA) and SR11237 on high glucose-induced inflammation in human umbilical endothelial vein endothelial cells (HUVECs) and explored the potential mechanism. Our results showed that the inflammation induced by high-glucose in HUVECs was mainly mediated by the activation of nuclear factor-B (NF- κB). High glucose-induced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were in comparison, significantly decreased by treatment with RXR. The effect of RXR agonists was mainly due to the inhibition of NF-κB activation. Using pharmacological inhibitors and siRNA, we confirmed that nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was an upstream activator of NF-κB. Furthermore, RXR agonists significantly inhibited high glucose-induced activation of NADPH oxidase and significantly decreased the production of reactive oxygen species (ROS). To explore whether the rapid inhibitory effects of RXR agonists were in fact mediated by RXR, we examined the effect of RXR downregulation by RXR siRNA. Our results showed that RXR siRNA largely abrogated the effects of RXR agonists, suggesting the requirement of RXR expression. Therefore, we have shown that RXR is involved in the regulation of NADPH oxidase- NF-κB signal pathway, as the RXR ligands antagonized the inflammatory response in HUVECs induced by high glucose.

  9. A Facile One Step Solution Route to Synthesize Cuprous Oxide Nanofluid

    Directory of Open Access Journals (Sweden)

    Shenoy U. Sandhya

    2013-05-01

    Full Text Available A cuprous oxide nanofluid stabilized by sodium lauryl sulfate, synthesized by using the one step method, has been reported. Nanofluids were synthesized by using a well‐ controlled surfactant‐assisted solution phase synthesis. The method involved reduction of copper acetate by glucose in a mixture of water and ethylene glycol serving as the base fluid. The synthesized fluid was characterized by X‐ray and electron diffraction techniques, in addition, transmission and field emission microscopic techniques and Fourier transform infra red spectroscopic analysis was undertaken. The rheological property, as well as the thermal conductivity of the fluid, were measured. The variation of reaction parameters considerably affected the size of the particles as well as the reaction rate. The uniform dispersion of the particles in the base fluid led to a stability period of three months under stationary state, augmenting the thermal conductivity of the nanofluid. The method is found to be simple, reliable and fast for the synthesis of Newtonian nanofluids containing cuprous oxide nanoparticles.

  10. Preparation of silver-cuprous oxide/stearic acid composite coating with superhydrophobicity on copper substrate and evaluation of its friction-reducing and anticorrosion abilities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peipei [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Chen, Xinhua [College of Chemistry and Chemical Engineering, Xuchang University, Xuchang 461000 (China); Yang, Guangbin; Yu, Laigui [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Zhang, Pingyu, E-mail: pingyu@henu.edu.cn [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China)

    2014-01-15

    A simple two-step solution immersion process was combined with surface-modification by stearic acid to prepare superhydrophobic coatings on copper substrates so as to reduce friction coefficient, increase wear resistance and improve the anticorrosion ability of copper. Briefly, cuprous oxide (Cu{sub 2}O) crystal coating with uniform and compact tetrahedron structure was firstly created by immersing copper substrate in 2 mol L{sup −1} NaOH solution. As-obtained Cu{sub 2}O coating was then immersed in 0.33 mmol L{sup −1} AgNO{sub 3} solution to incorporate silver nanoparticles, followed by modification with stearic acid (denoted as SA) coating to achieve hydrophobicity. The surface morphology and chemical composition of silver-cuprous oxide/stearic acid (denoted as Ag-Cu{sub 2}O/SA) composite coating were investigated using a scanning electron microscope and an X-ray photoelectron spectroscope (XPS); and its phase structure was examined with an X-ray diffractometer (XRD). Moreover, the contact angle of water on as-prepared Ag-Cu{sub 2}O/SA composite coating was measured, and its friction-reducing and anticorrosion abilities were evaluated. It was found that as-prepared Ag-Cu{sub 2}O/SA composite coating has a water contact angle of as high as 152.4{sup o} and can provide effective friction-reducing, wear protection and anticorrosion protection for copper substrate, showing great potential for surface-modification of copper.

  11. Potassium-doped carbon nanotubes toward the direct electrochemistry of cholesterol oxidase and its application in highly sensitive cholesterol biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaorong [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Xu Jingjuan, E-mail: xujj@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Chen Hongyuan [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2011-10-30

    We demonstrate herein a newly developed serum total cholesterol biosensor by using the direct electron transfer of cholesterol oxidase (ChOx), which is based on the immobilization of cholesterol oxidase and cholesterol esterase (ChEt) on potassium-doped multi-walled carbon nanotubes (KMWNTs) modified electrodes. The KMWNTs accelerate the electron transfer from electrode surface to the immobilized ChOx, achieving the direct electrochemistry of ChOx and maintaining its bioactivity. As a new platform in cholesterol analysis, the resulting electrode (ChOx/KMWNTs/GCE) exhibits a sensitive response to free cholesterol, with a linear range of 0.050-16.0 {mu}mol L{sup -1} and a detection limit of 5.0 nmol L{sup -1} (S/N = 3). Coimmobilization of ChEt and ChOx (ChEt/ChOx/KMWNTs/GCE) allows the determination of both free cholesterol and esterified cholesterol. The resulting biosensor shows the same linear range of 0.050-16.0 {mu}mol L{sup -1} for free cholesterol and cholesteryl oleate, with the detection limit of 10.0 and 12.0 nmol L{sup -1} (S/N = 3), respectively. The concentrations of total (free and esterified) cholesterol in human serum samples, determined by using the techniques developed in the present study, are in good agreement with those determined by the well-established techniques using the spectrophotometry.

  12. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua, E-mail: yhshen@ahu.edu.cn

    2016-01-01

    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu{sub 2}O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu{sub 2}O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu{sub 2}O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu{sub 2}O nanoparticles), or two component systems (RGO/Cu{sub 2}O composite hydrogel and PANI/Cu{sub 2}O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu{sub 2}O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  13. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    International Nuclear Information System (INIS)

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua

    2016-01-01

    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu_2O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu_2O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu_2O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu_2O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu_2O nanoparticles), or two component systems (RGO/Cu_2O composite hydrogel and PANI/Cu_2O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu_2O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu_2O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  14. Defect engineering of the electronic transport through cuprous oxide interlayers

    KAUST Repository

    Fadlallah, Mohamed M.

    2016-06-03

    The electronic transport through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work.

  15. Microwave—enhanced Mannich Condensation of Terminal Alkynes,Primary Amines with Paraformaldehyde on cuprous Iodide Doped Alumina under Solvent Free Conditions

    Institute of Scientific and Technical Information of China (English)

    王磊; 李品华

    2003-01-01

    A microwave-enhanced,solventless Mannich condensation of terminal alkynes,primary amines with paraformaldehyde on cuprous iodide doped alumina has been investigated.The structures of products depend on the ratio of alkyne to amine and paraformaldehyde.

  16. Band offsets of n-type electron-selective contacts on cuprous oxide (Cu{sub 2}O) for photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, Riley E., E-mail: rbrandt@alum.mit.edu, E-mail: buonassisi@mit.edu; Lee, Yun Seog; Buonassisi, Tonio, E-mail: rbrandt@alum.mit.edu, E-mail: buonassisi@mit.edu [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Young, Matthew; Dameron, Arrelaine; Teeter, Glenn [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Park, Helen Hejin; Chua, Danny; Gordon, Roy G. [Harvard University, Cambridge, Massachusetts 02139 (United States)

    2014-12-29

    The development of cuprous oxide (Cu{sub 2}O) photovoltaics (PVs) is limited by low device open-circuit voltages. A strong contributing factor to this underperformance is the conduction-band offset between Cu{sub 2}O and its n-type heterojunction partner or electron-selective contact. In the present work, a broad range of possible n-type materials is surveyed, including ZnO, ZnS, Zn(O,S), (Mg,Zn)O, TiO{sub 2}, CdS, and Ga{sub 2}O{sub 3}. Band offsets are determined through X-ray photoelectron spectroscopy and optical bandgap measurements. A majority of these materials is identified as having a negative conduction-band offset with respect to Cu{sub 2}O; the detrimental impact of this on open-circuit voltage (V{sub OC}) is evaluated through 1-D device simulation. These results suggest that doping density of the n-type material is important as well, and that a poorly optimized heterojunction can easily mask changes in bulk minority carrier lifetime. Promising heterojunction candidates identified here include Zn(O,S) with [S]/[Zn] ratios >70%, and Ga{sub 2}O{sub 3}, which both demonstrate slightly positive conduction-band offsets and high V{sub OC} potential. This experimental protocol and modeling may be generalized to evaluate the efficiency potential of candidate heterojunction partners for other PV absorbers, and the materials identified herein may be promising for other absorbers with low electron affinities.

  17. One-step synthesis and properties of monolithic photoluminescent ruby colored cuprous oxide antimony oxide glass nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Som, Tirtha [Glass Science and Technology Section, Glass Division, Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research (CSIR, India), 196, Raja S.C. Mullick Road, Kolkata 700032 (India); Karmakar, Basudeb, E-mail: basudebk@cgcri.res.in [Glass Science and Technology Section, Glass Division, Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research (CSIR, India), 196, Raja S.C. Mullick Road, Kolkata 700032 (India)

    2011-04-14

    Research highlights: > Single-step synthesis of Cu{sub 2}O, Cu{sub y}Sb{sub 2-x}(O,OH){sub 6-7} (y {<=} 2, x {<=} 1) and Cu nanocrystals co-doped novel antimony oxide glass hybrid nanocomposites. > Yellow and orange colored nanocomposites shows size-controlled band gap shift of Cu{sub 2}O. > Red nanocomposite exhibits surface plasmon resonance band due to metallic Cu. > They exhibit broad deep-red photoluminescence emission under various UV excitation wavelengths. - Abstract: Cuprous oxide (Cu{sub 2}O) antimony glass (K{sub 2}O-B{sub 2}O{sub 3}-Sb{sub 2}O{sub 3}) monolithic nanocomposites having brilliant yellow to ruby red color have been synthesized by a single-step melt-quench technique involving in situ thermochemical reduction of Cu{sup 2+} (CuO) by the reducing glass matrix without using any external reducing agent. The X-ray diffraction (XRD), infrared transmission and reflection spectra, and selected area electron diffraction analysis support the reduction of Cu{sup 2+} to Cu{sup +} with the formation of Cu{sub 2}O nanoclusters along with Cu{sub y}Sb{sub 2-x}(O,OH){sub 6-7} (y {<=} 2, x {<=} 1) nanocrystalline phases while Cu{sup 0} nanoclusters are formed at very high Cu concentration. The UV-vis spectra of the yellow and orange colored nanocomposites show size-controlled band gap shift of the semiconductor (Cu{sub 2}O) nanocrystallites embedded in the glasses while the red nanocomposite exhibits surface plasmon resonance band at 529 nm due to metallic Cu. Transmission electron microscopic image advocates the formation of nanocystallites (5-42 nm). Photoluminescence emission studies show broad red emission band around 626 nm under various excitation wavelengths from 210 to 270 nm.

  18. Monoamine Oxidase Inhibitors (MAOIs)

    Science.gov (United States)

    ... health-medications/index.shtml. Accessed May 16, 2016. Hirsch M, et al. Monoamine oxidase inhibitors (MAOIs) for ... www.uptodate.com/home. Accessed May 16, 2016. Hirsch M, et al. Discontinuing antidepressant medications in adults. ...

  19. Polyphenol Oxidase Enzyme and Inactivation Methods

    Directory of Open Access Journals (Sweden)

    Leman Yılmaz

    2018-03-01

    Full Text Available Polyphenol oxidase enzyme is found in vegetables and fruits, as well as in some animal organs and microorganisms. Polyphenol oxidase enzyme responsible for enzymatic browning is a group of copper proteins that catalyses the oxidation of phenolic compounds to quinones, which produce brown pigments, commonly found in fruits and vegetables. During the industrial preparation of fruits and vegetables, results of catalytic effect of polyphenol oxidase causes enzymatic browning. Enzymatic browning impairs the appearance of products containing phenolic compounds along with undesirable colour, odor and taste formation and significant loss of nutritional value of the products. This affects the acceptability of the products by the consumers and causes economic losses. In this review, some characteristics of polyphenol oxidase enzyme in different fruits and vegetables have been reviewed and information about chemical antibrowning agents, thermal applications, irradiation applications and alternative methods such as high pressure processing, pulse electric field, supercritical carbon dioxide and ultrasound applications to inactivate this enzyme has been presented.

  20. High-performance liquid chromatography coupled with post-column dual-bioactivity assay for simultaneous screening of xanthine oxidase inhibitors and free radical scavengers from complex mixture.

    Science.gov (United States)

    Li, D Q; Zhao, J; Li, S P

    2014-06-06

    Xanthine oxidase (XO) can catalyze hypoxanthine and xanthine to generate uric acid and reactive oxygen species (ROS), including superoxide anion radical (O₂(•-)) and hydrogen peroxide. XO inhibitors and free radical scavengers are beneficial to the treatment of gout and many related diseases. In the present study, an on-line high-performance liquid chromatography (HPLC) coupled with post-column dual-bioactivity assay was established and successfully applied to simultaneously screening of XO inhibitors and free radical scavengers from a complex mixture, Oroxylum indicum extract. The integrated system of HPLC separation, bioactivity screening and mass spectrometry identification was proved to be simple and effective for rapid and sensitive screening of individual bioactive compounds in complex mixtures. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Surface Induced Dissociation Coupled with High Resolution Mass Spectrometry Unveils Heterogeneity of a 211 kDa Multicopper Oxidase Protein Complex

    Science.gov (United States)

    Zhou, Mowei; Yan, Jing; Romano, Christine A.; Tebo, Bradley M.; Wysocki, Vicki H.; Paša-Tolić, Ljiljana

    2018-01-01

    Manganese oxidation is an important biogeochemical process that is largely regulated by bacteria through enzymatic reactions. However, the detailed mechanism is poorly understood due to challenges in isolating and characterizing these unknown enzymes. A manganese oxidase, Mnx, from Bacillus sp. PL-12 has been successfully overexpressed in active form as a protein complex with a molecular mass of 211 kDa. We have recently used surface induced dissociation (SID) and ion mobility-mass spectrometry (IM-MS) to release and detect folded subcomplexes for determining subunit connectivity and quaternary structure. The data from the native mass spectrometry experiments led to a plausible structural model of this multicopper oxidase, which has been difficult to study by conventional structural biology methods. It was also revealed that each Mnx subunit binds a variable number of copper ions. Becasue of the heterogeneity of the protein and limited mass resolution, ambiguities in assigning some of the observed peaks remained as a barrier to fully understanding the role of metals and potential unknown ligands in Mnx. In this study, we performed SID in a modified Fourier transform-ion cyclotron resonance (FTICR) mass spectrometer. The high mass accuracy and resolution offered by FTICR unveiled unexpected artificial modifications on the protein that had been previously thought to be iron bound species based on lower resolution spectra. Additionally, isotopically resolved spectra of the released subcomplexes revealed the metal binding stoichiometry at different structural levels. This method holds great potential for in-depth characterization of metalloproteins and protein-ligand complexes. [Figure not available: see fulltext.

  2. Characterization of a Highly Thermostable and Organic Solvent-Tolerant Copper-Containing Polyphenol Oxidase with Dye-Decolorizing Ability from Kurthia huakuii LAM0618T.

    Directory of Open Access Journals (Sweden)

    Xiang Guo

    Full Text Available Laccases are green biocatalysts that possess attractive advantages for the treatment of resistant environmental pollutants and dye effluents. A putative laccase-like gene, laclK, encoding a protein of 29.3 kDa and belonging to the Cu-oxidase_4 superfamily, was cloned and overexpressed in Escherichia coli. The purified recombinant protein LaclK (LaclK was able to oxidize typical laccase substrates such as 2,6-dimethoxyphenol and l-dopamine. The characteristic adsorption maximums of typical laccases at 330 nm and 610 nm were not detected for LaclK. Cu2+ was essential for substrate oxidation, but the ratio of copper atoms/molecule of LaclK was determined to only be 1:1. Notably, the optimal temperature of LaclK was 85°C with 2,6-dimethoxyphenol as substrates, and the half-life approximately 3 days at 80°C. Furthermore, 10% (v/v organic solvents (methanol, ethanol, isopropyl alcohol, butyl alcohol, Triton x-100 or dimethyl sulfoxide could promote enzymatic activity. LaclK exhibited wide-spectrum decolorization ability towards triphenylmethane dyes, azo dyes and aromatic dyes, decolorizing 92% and 94% of Victoria Blue B (25 μM and Ethyl Violet (25 μM, respectively, at a concentration of 60 U/L after 1 h of incubation at 60°C. Overall, we characterized a novel thermostable and organic solvent-tolerant copper-containing polyphenol oxidase possessing dye-decolorizing ability. These unusual properties make LaclK an alternative for industrial applications, particularly processes that require high-temperature conditions.

  3. Multilayer core-shell structured composite paper electrode consisting of copper, cuprous oxide and graphite assembled on cellulose fibers for asymmetric supercapacitors

    Science.gov (United States)

    Wan, Caichao; Jiao, Yue; Li, Jian

    2017-09-01

    An easily-operated and inexpensive strategy (pencil-drawing-electrodeposition-electro-oxidation) is proposed to synthesize a novel class of multilayer core-shell structured composite paper electrode, which consists of copper, cuprous oxide and graphite assembled on cellulose fibers. This interesting electrode structure plays a pivotal role in providing more active sites for electrochemical reactions, facilitating ion and electron transport and shorting their diffusion pathways. This electrode demonstrates excellent electrochemical properties with a high specific capacitance of 601 F g-1 at 2 A g-1 and retains 83% of this capacitance when operated at an ultrahigh current density of 100 A g-1. In addition, a high energy density of 13.4 W h kg-1 at the power density of 0.40 kW kg-1 and a favorable cycling stability (95.3%, 8000 cycles) were achieved for this electrode. When this electrode was assembled into an asymmetric supercapacitor with carbon paper as negative electrode, the device displays remarkable electrochemical performances with a large areal capacitances (122 mF cm-2 at 1 mA cm-2), high areal energy density (10.8 μW h cm-2 at 402.5 μW cm-2) and outstanding cycling stability (91.5%, 5000 cycles). These results unveil the potential of this composite electrode as a high-performance electrode material for supercapacitors.

  4. Observation of confinement effects through liner and nonlinear absorption spectroscopy in cuprous oxide

    Science.gov (United States)

    Sekhar, H.; Rakesh Kumar, Y.; Narayana Rao, D.

    2015-02-01

    Cuprous oxide nano clusters, micro cubes and micro particles were successfully synthesized by reducing copper (II) salt with ascorbic acid in the presence of sodium hydroxide via a co-precipitation method. The X-ray diffraction studies revealed the formation of pure single phase cubic. Raman spectrum shows the inevitable presence of CuO on the surface of the Cu2O powders which may have an impact on the stability of the phase. Transmission electron microscopy (TEM) data revealed that the morphology evolves from nanoclusters to micro cubes and micro particles by increasing the concentration of NaOH. Linear optical measurements show that the absorption peak maximum shifts towards red with changing morphology from nano clusters to micro cubes and micro particles. The nonlinear optical properties were studied using open aperture Z-scan technique with 532 nm, 6 ns laser pulses. Samples exhibited saturable as well as reverse saturable absorption. The results show that the transition from SA to RSA is ascribed to excited-state absorption (ESA) induced by two-photon absorption (TPA) process. Due to confinement effects (enhanced band gap) we observed enhanced nonlinear absorption coefficient (βeff) in the case of nano-clusters compared to their micro-cubes and micro-particles.

  5. Controlling the Optical and Magnetic Properties of Nanostructured Cuprous Oxide Synthesized from Waste Electric Cables

    Science.gov (United States)

    Abdelbasir, S. M.; El-Sheikh, S. M.; Rashad, M. M.; Rayan, D. A.

    2018-03-01

    Cuprous oxide Cu2O nanopowders were purposefully synthesised from waste electric cables (WECs) via a simple precipitation route at room temperature using lactose as a reducing agent. In this regard, dimethyl sulfoxide (DMSO) was first applied as an organic solvent for the dissolution of the cable insulating materials. Several parameters were investigated during dissolution of WECs such as dissolution temperature, time and solid/liquid ratio to determine the dissolution percentage of the insulating materials in DMSO. The morphology and the optical properties of the formed Cu2O particles were investigated using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy and UV-visible-near IR spectrophotometer. XRD data confirmed the presence of single crystalline phase of Cu2O nanoparticles. FE-SEM and TEM images revealed spherical, cubic and octahedral shapes with the various particle sizes ranged from 16 to 57 nm depending on the synthesis conditions. A possible mechanism explaining the Cu2O nanostructures formation was proposed. The band gap energies of the Cu2O nanostructures were estimated and the values were located between 1.5 and 2.08 eV. Photoluminescence spectroscopy analysis clearly showed a noticeably blue-shifted emission for the synthesized samples compared to spectrum of the bulk. Eventually, magnetic properties of the synthesized nanoparticles have been measured by vibrating sample magnetometer and the attained results implied that the synthesized particles are weakly ferromagnetic in nature at normal temperature.

  6. Effect of cuprous oxide with different sizes on thermal and combustion behaviors of unsaturated polyester resin.

    Science.gov (United States)

    Hou, Yanbei; Hu, Weizhao; Gui, Zhou; Hu, Yuan

    2017-07-15

    Cuprous oxide (Cu 2 O) as an effective catalyst has been applied to enhance the fire safety of unsaturated polyester resin (UPR), but the particle size influence on combustion behaviors has not been previously reported. Herein, the UPR/Cu 2 O composites (metal oxide particles with average particle-size of 10, 100, and 200nm) were successfully synthesized by thermosetting process. The effects of Cu 2 O with different sizes on thermostability and combustion behaviors of UPR were characterized by TGA, MCC, TG-IR, FTIR, and SSTF. The results revel that the addition of Cu 2 O contributes to sufficient decomposition of oxygen-containing compounds, which is beneficial to the release of nontoxic compounds. The smallest-sized Cu 2 O performs the excellent catalytic decomposition effect and promotes the complete combustion of UPR, which benefits the enhancement of fire safety. While the other additives retard pyrolysis process and yield more char residue, and thus the flame retardancy of UPR composites was improved. Therefore, catalysis plays a major role for smaller-sized particles during thermal decomposition of matrix, while flame retarded effect became gradual distinctly for the larger-sized additives. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Hydrogen sulfide inhibits high glucose-induced NADPH oxidase 4 expression and matrix increase by recruiting inducible nitric oxide synthase in kidney proximal tubular epithelial cells.

    Science.gov (United States)

    Lee, Hak Joo; Lee, Doug Yoon; Mariappan, Meenalakshmi M; Feliers, Denis; Ghosh-Choudhury, Goutam; Abboud, Hanna E; Gorin, Yves; Kasinath, Balakuntalam S

    2017-04-07

    High-glucose increases NADPH oxidase 4 (NOX4) expression, reactive oxygen species generation, and matrix protein synthesis by inhibiting AMP-activated protein kinase (AMPK) in renal cells. Because hydrogen sulfide (H 2 S) inhibits high glucose-induced matrix protein increase by activating AMPK in renal cells, we examined whether H 2 S inhibits high glucose-induced expression of NOX4 and matrix protein and whether H 2 S and NO pathways are integrated. High glucose increased NOX4 expression and activity at 24 h in renal proximal tubular epithelial cells, which was inhibited by sodium hydrosulfide (NaHS), a source of H 2 S. High glucose decreased AMPK phosphorylation and activity, which was restored by NaHS. Compound C, an AMPK inhibitor, prevented NaHS inhibition of high glucose-induced NOX4 expression. NaHS inhibition of high glucose-induced NOX4 expression was abrogated by N (ω)-nitro-l-arginine methyl ester, an inhibitor of NOS. NaHS unexpectedly augmented the expression of inducible NOS (iNOS) but not endothelial NOS. iNOS siRNA and 1400W, a selective iNOS inhibitor, abolished the ameliorative effects of NaHS on high glucose-induced NOX4 expression, reactive oxygen species generation, and, matrix laminin expression. Thus, H 2 S recruits iNOS to generate NO to inhibit high glucose-induced NOX4 expression, oxidative stress, and matrix protein accumulation in renal epithelial cells; the two gasotransmitters H 2 S and NO and their interaction may serve as therapeutic targets in diabetic kidney disease. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Impact of high pressure processing on color, bioactive compounds, polyphenol oxidase activity, and microbiological attributes of pumpkin purée.

    Science.gov (United States)

    González-Cebrino, Francisco; Durán, Rocío; Delgado-Adámez, Jonathan; Contador, Rebeca; Bernabé, Rosario Ramírez

    2016-04-01

    Physicochemical parameters, bioactive compounds' content (carotenoids and total phenols), total antioxidant activity, and enzymatic activity of polyphenol oxidase (PPO) were evaluated after high pressure processing (HPP) on a pumpkin purée (cv. 'Butternut'). Three pressure levels (400, 500, and 600 MPa) were combined with three holding times (200, 400, and 600 s). The applied treatments reduced the levels of total aerobic mesophilic (TAM), total psychrophilic and psychrotrophic bacteria (TPP), and molds and yeasts (M&Y). All applied treatments did not affect enzymatic activity of PPO. Pressure level increased CIE L* values, which could enhance the lightness perception of high pressure (HP)-treated purées. No differences were found between the untreated and HP-treated purées regarding total phenols and carotenoids content (lutein, α-carotene, and β-carotene) and total antioxidant activity. HPP did not affect most quality parameters and maintained the levels of bioactive compounds. However, it did not achieve the complete inhibition of PPO, which could reduce the shelf-life of the pumpkin purée. © The Author(s) 2015.

  9. Effects of high pressure homogenization on the activity, stability, kinetics and three-dimensional conformation of a glucose oxidase produced by Aspergillus niger.

    Directory of Open Access Journals (Sweden)

    Alline Artigiani Lima Tribst

    Full Text Available High pressure homogenization (HPH is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5-6.0 and a remarkable activity increase (30-300% at pH 6.5 in all tested temperatures (15, 50 and 75°C. The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C also caused a reduction of activity. Interestingly, at lower temperatures (15°C the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO.

  10. Isolated sulfite oxidase deficiency.

    Science.gov (United States)

    Rupar, C A; Gillett, J; Gordon, B A; Ramsay, D A; Johnson, J L; Garrett, R M; Rajagopalan, K V; Jung, J H; Bacheyie, G S; Sellers, A R

    1996-12-01

    Isolated sulfite oxidase (SO) deficiency is an autosomal recessively inherited inborn error of sulfur metabolism. In this report of a ninth patient the clinical history, laboratory results, neuropathological findings and a mutation in the sulfite oxidase gene are described. The data from this patient and previously published patients with isolated sulfite oxidase deficiency and molybdenum cofactor deficiency are summarized to characterize this rare disorder. The patient presented neonatally with intractable seizures and did not progress developmentally beyond the neonatal stage. Dislocated lenses were apparent at 2 months. There was increased urine excretion of sulfite and S-sulfocysteine and a decreased concentration of plasma cystine. A lactic acidemia was present for 6 months. Liver sulfite oxidase activity was not detectable but xanthine dehydrogenase activity was normal. The boy died of respiratory failure at 32 months. Neuropathological findings of cortical necrosis and extensive cavitating leukoencephalopathy were reminiscent of those seen in severe perinatal asphyxia suggesting an etiology of energy deficiency. A point mutation that resulted in a truncated protein missing the molybdenum-binding site has been identified.

  11. Comparison of Poly Aluminum Chloride and Chlorinated Cuprous for Chemical Oxygen Demand and Color Removal from Kashan Textile Industries Company Wastewater

    Directory of Open Access Journals (Sweden)

    Hoseindoost Gh.1 MSPH,

    2016-08-01

    Full Text Available Aims Textile wastewaters are the most important health and environmental problems in Kashan. This research was aimed to compare the poly aluminum chloride and chlorinated cuprous efficiency for removal of Chemical Oxygen Demand (COD and color from Kashan Textile Industries Company wastewater. Materials & Methods This experimental bench scale study in a batch system was conducted on 20 composed wastewater samples collected from Kashan Textile Industries Company raw wastewater. During 5 months, in the beginning of every week a day was selected randomly and in the day a composed sample was taken and studied. PAC at the doses of 10, 20, 30, 40 and 50mg.l-1 and chlorinated cuprous at the doses of 100, 200, 300, 400 and 500mg.l-1 were applied. The optimum pH also optimum concentration of PAC and chlorinated cuprous were determined using Jar test. The data was analyzed by SPSS 16 using descriptive statistics and Fisher Exact test. Findings The average concentration of COD in the raw textile wastewater was 2801.56±1398.29mg.l-1. The average COD concentration has been decreased to 1125.47±797.55mg.l-1. There was a significant difference between the effects of these two coagulants efficiency (p<0.05. The average COD removal efficiency for chlorinated cuprous and PAC was 58.52% and 72.56%, respectively. Also, the average color removal efficiency by chlorinated cuprous and PAC were 17.23 and 64.45%, respectively. Conclusion PAC is more efficient than chlorinated cuprous for both COD and color removal from KTIC wastewater.

  12. Cuprous oxide created on sepiolite: Preparation, characterization, and photocatalytic activity in treatment of red water from 2,4,6-trinitrotoluene manufacturing

    International Nuclear Information System (INIS)

    Zhu, Qingwei; Zhang, Yihe; Lv, Fengzhu; Chu, Paul K.; Ye, Zhengfan; Zhou, Fengshan

    2012-01-01

    Highlights: ► Cu 2 O crystals were firstly created on the natural sepiolite fibers. ► The structures of the sepiolite are altered when acidized, benefiting the immobility of cuprous oxide crystals. ► The carrier sepiolite improves efficiently the photocatalytic activity of cuprous oxide crystals. ► Cu 2 O/sepiolite composites show superior photocatalytic activity for the degradation of red water. - Abstract: Cuprous oxide is firstly created on acidized sepiolite (AS) by a simple deposition method for photocatalytic degradation of the red water produced from 2,4,6-trinitrotoluene (TNT) manufacturing. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), ultraviolet-visible diffuse reflection absorptive spectroscopy (UV–vis/DRS), and Fourier transform infrared (FT-IR) spectroscopy are used to characterize the photocatalyst composites. Gas chromatography/mass spectrometry (GC/MS) is employed to determine the organic constituents in the red water. The results show that the cuprous oxide particles can be immobilized on the surface of the AS fibers and the structure of the AS is altered when cuprous oxide interacts with AS via chemical reactions besides physical adsorption. The AS improves the optical properties of cuprous oxide and red-shifts the band gap thereby enhancing the utilization of visible light. The Cu 2 O/AS composites demonstrate excellent photocatalytic performance in the degradation of red water. 87.0% of red water can be photocatalytically degraded by Cu 2 O/AS after illumined for 5 h and a majority of organic components of red water except 1,3,5-trinitrobenzene were degraded according to GC–MS analysis.

  13. Fabrication of cuprous chloride films on copper substrate by chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yu-Ting; Ci, Ji-Wei; Tu, Wei-Chen [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Uen, Wu-Yih, E-mail: uenwuyih@ms37.hinet.net [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Lan, Shan-Ming [Department of Electronic Engineering, College of Electrical Engineering and Computer Science, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Yang, Tsun-Neng; Shen, Chin-Chang; Wu, Chih-Hung [Institute of Nuclear Energy Research, P.O. Box 3-11, Lungtan 32500, Taiwan (China)

    2015-09-30

    Polycrystalline CuCl films were fabricated by chemical bath deposition (CBD) on a Cu substrate at a low solution temperature of 90 °C. Continuous CuCl films were prepared using the copper (II) chloride (CuCl{sub 2}) compound as the precursor for both the Cu{sup 2+} and Cl{sup −} sources, together with repeated HCl dip treatments. An HCl dip pretreatment of the substrate favored the nucleation of CuCl crystallites. Further, interrupting the film deposition and including an HCl dip treatment of the film growth surface facilitated the deposition of a full-coverage CuCl film. A dual beam (FIB/SEM) system with energy dispersive spectrometry facilities attached revealed a homogeneous CuCl layer with a flat-top surface and an average thickness of about 1 μm. Both the excitonic and biexcitonic emission lines were well-resolved in the 6.4 K photoluminescence spectra. In particular, the free exciton emission line was observable at room temperature, indicating the good quality of the CuCl films prepared by CBD. - Highlights: • Cuprous chloride (CuCl) was prepared on Cu substrate by chemical bath deposition. • HCl dip treatments facilitated the deposition of a full-coverage CuCl film. • A homogeneous elemental distribution was recognized for the deposited CuCl layer. • Excitonic and biexcitonic photoluminescence lines of CuCl films were well-resolved. • The free exciton emission line of CuCl films was observable at room temperature.

  14. Cytotoxicity of cuprous oxide nanoparticles to fish blood cells: hemolysis and internalization

    Energy Technology Data Exchange (ETDEWEB)

    Chen Liqiang, E-mail: chenlq@ynu.edu.cn; Kang Bin [Yunnan University, Asian International Rivers Center, Yunnan Key Laboratory of International Rivers and Trans-boundary Eco-security (China); Ling Jian [Yunnan University, College of Chemistry and Chemical Engineering (China)

    2013-03-15

    Cuprous oxide nanoparticles (Cu{sub 2}O NPs) possess unique physical and chemical properties which are employed in a broad variety of applications. However, little is known about the adverse effects of Cu{sub 2}O NPs on organisms. In the current study, in vitro cytotoxicity of Cu{sub 2}O NPs (ca. 60 nm in diameter) to the blood cells of freshwater fish Carassius auratus was evaluated. A concentration-dependent hemolytic activity of Cu{sub 2}O NPs to red blood cells (RBCs) and the phagocytosis of Cu{sub 2}O NPs by leukocytes were revealed. The results showed that dosages of Cu{sub 2}O NPs greater than 40 {mu}g/mL were toxic to blood cells, and could cause serious membrane damage to RBCs. The EC{sub 50} value of Cu{sub 2}O NPs as obtained from RBCs and whole blood exposure was 26 and 63 {mu}g/mL, respectively. The generation of reactive oxygen species and the direct interaction between Cu{sub 2}O NPs and the cell membrane were suggested as the possible mechanism for cytotoxicity, and the intrinsic hemolytic active of Cu{sub 2}O NPs was the main contributor to the toxicity rather than solubilized copper ions. The adsorption of plasma proteins on the surfaces of Cu{sub 2}O NPs led to their aggregation in whole blood, and aggregate formation can significantly alleviate the hemolytic effect and subsequently mediate the phagocytosis of Cu{sub 2}O NPs by leukocytes.

  15. Carbon-layer-protected cuprous oxide nanowire arrays for efficient water reduction

    KAUST Repository

    Zhang, Zhonghai

    2013-02-26

    In this work, we propose a solution-based carbon precursor coating and subsequent carbonization strategy to form a thin protective carbon layer on unstable semiconductor nanostructures as a solution to the commonly occurring photocorrosion problem of many semiconductors. A proof-of-concept is provided by using glucose as the carbon precursor to form a protective carbon coating onto cuprous oxide (Cu2O) nanowire arrays which were synthesized from copper mesh. The carbon-layer-protected Cu2O nanowire arrays exhibited remarkably improved photostability as well as considerably enhanced photocurrent density. The Cu2O nanowire arrays coated with a carbon layer of 20 nm thickness were found to give an optimal water splitting performance, producing a photocurrent density of -3.95 mA cm-2 and an optimal photocathode efficiency of 0.56% under illumination of AM 1.5G (100 mW cm-2). This is the highest value ever reported for a Cu 2O-based electrode coated with a metal/co-catalyst-free protective layer. The photostability, measured as the percentage of the photocurrent density at the end of 20 min measurement period relative to that at the beginning of the measurement, improved from 12.6% on the bare, nonprotected Cu2O nanowire arrays to 80.7% on the continuous carbon coating protected ones, more than a 6-fold increase. We believe that the facile strategy presented in this work is a general approach that can address the stability issue of many nonstable photoelectrodes and thus has the potential to make a meaningful contribution in the general field of energy conversion. © 2013 American Chemical Society.

  16. The effect of heat on DNA degradation by the 1, 10-phenanthroline-cuprous ion complex

    International Nuclear Information System (INIS)

    Nagle, W.A.; Henle, K.J.; Willingham, W.M.; Sorenson, J.R.J.; McClellan, J.L.; Moss, A.J.

    1987-01-01

    The 1, 10-phenanthroline-cuprous ion complex (OP)/sub 2/Cu/sup +/ exhibits artificial DNase activity which closely parallels micrococcal nuclease. Using cell-free systems and in situ generated (OP)/sub 2/Cu/sup +/, other studies have shown a requirement for a reducing agent as well as O/sub 2/ or H/sub 2/O/sub 2/ to degrade DNA to acid-soluble fragments. The authors investigated the influence of hyperthermia on the degradation of V79 cell DNA using the (OP)/sub 2/Cu/sup +/-ascorbate system. The (OP)/sub 2/Cu/sup +/ complex was synthesized and characterized prior to cell treatment. Cells were prelabeled with /sup 3/H-TdR (control) or /sup 14/C-TdR (treated) and exposed 10 minutes at 45 0 C, followed by a 30 minute incubation with lμM (OP)/sub 2/Cu/sup +/ and 10μM as corbate in balanced salts solution. Cellular DNA was assayed using the alkaline elution technique. Heated cells incubated with lμM (OP)/sub 2/Cu/sup +/ or 10μM ascorbate exhibited a 300 rad equivalent increase in strand breaks over the unheated control. Incubation of cells with either lμM (OP)/sub 2/Cu/sup +/ or 10μM ascorbate alone did not induce strand breaks. These results suggests that heating initially increases the susceptibility of DNA to attack by the (OP)/sub 2/Cu/sup +/-ascorbate system

  17. On-chip highly sensitive saliva glucose sensing using multilayer films composed of single-walled carbon nanotubes, gold nanoparticles, and glucose oxidase

    Directory of Open Access Journals (Sweden)

    Wenjun Zhang

    2015-06-01

    Full Text Available It is very important for human health to rapidly and accurately detect glucose levels in biological environments, especially for diabetes mellitus. We proposed a simple, highly sensitive, accurate, convenient, low-cost, and disposable glucose biosensor on a single chip. A working (sensor electrode, a counter electrode, and a reference electrode are integrated on a single chip through micro-fabrication. The working electrode is functionalized through a layer-by-layer (LBL assembly of single-walled carbon nanotubes (SWNTs and multilayer films composed of chitosan (CS, gold nanoparticles (GNp, and glucose oxidase (GOx to obtain high sensitivity and accuracy. The glucose sensor has following features: (1 direct electron transfer between GOx and the electrode surface; (2 on-a-chip; (3 glucose detection down to 0.1 mg/dL (5.6 μM; (4 good sensing linearity over 0.017–0.81 mM; (5 high sensitivity (61.4 μA/mM-cm2 with a small reactive area (8 mm2; (6 fast response; (7 high reproducibility and repeatability; (8 reliable and accurate saliva glucose detection. Thus, this disposable biosensor will be an alternative for real time tracking of glucose levels from body fluids, e.g. saliva, in a noninvasive, pain-free, accurate, and continuous way. In addition to being used as a disposable glucose biosensor, it also provides a suitable platform for on-chip electrochemical sensing for other chemical agents and biomolecules.

  18. Calcineurin Aβ regulates NADPH oxidase (Nox) expression and activity via nuclear factor of activated T cells (NFAT) in response to high glucose.

    Science.gov (United States)

    Williams, Clintoria R; Gooch, Jennifer L

    2014-02-21

    Hypertrophy is an adaptive response that enables organs to appropriately meet increased functional demands. Previously, we reported that calcineurin (Cn) is required for glomerular and whole kidney hypertrophy in diabetic rodents (Gooch, J. L., Barnes, J. L., Garcia, S., and Abboud, H. E. (2003). Calcineurin is activated in diabetes and is required for glomerular hypertrophy and ECM accumulation. Am. J. Physiol. Renal Physiol. 284, F144-F154; Reddy, R. N., Knotts, T. L., Roberts, B. R., Molkentin, J. D., Price, S. R., and Gooch, J. L. (2011). Calcineurin Aβ is required for hypertrophy but not matrix expansion in the diabetic kidney. J. Cell Mol. Med. 15, 414-422). Because studies have also implicated the reactive oxygen species-generating enzymes NADPH oxidases (Nox) in diabetic kidney responses, we tested the hypothesis that Nox and Cn cooperate in a common signaling pathway. First, we examined the role of the two main isoforms of Cn in hypertrophic signaling. Using primary kidney cells lacking a catalytic subunit of Cn (CnAα(-/-) or CnAβ(-/-)), we found that high glucose selectively activates CnAβ, whereas CnAα is constitutively active. Furthermore, CnAβ but not CnAα mediates hypertrophy. Next, we found that chronic reactive oxygen species generation in response to high glucose is attenuated in CnAβ(-/-) cells, suggesting that Cn is upstream of Nox. Consistent with this, loss of CnAβ reduces basal expression and blocks high glucose induction of Nox2 and Nox4. Inhibition of nuclear factor of activated T cells (NFAT), a CnAβ-regulated transcription factor, decreases Nox2 and Nox4 expression, whereas NFAT overexpression increases Nox2 and Nox4, indicating that the CnAβ/NFAT pathway modulates Nox. These data reveal that the CnAβ/NFAT pathway regulates Nox and plays an important role in high glucose-mediated hypertrophic responses in the kidney.

  19. High-performance glucose biosensor based on chitosan-glucose oxidase immobilized polypyrrole/Nafion/functionalized multi-walled carbon nanotubes bio-nanohybrid film.

    Science.gov (United States)

    Shrestha, Bishnu Kumar; Ahmad, Rafiq; Mousa, Hamouda M; Kim, In-Gi; Kim, Jeong In; Neupane, Madhav Prasad; Park, Chan Hee; Kim, Cheol Sang

    2016-11-15

    A highly electroactive bio-nanohybrid film of polypyrrole (PPy)-Nafion (Nf)-functionalized multi-walled carbon nanotubes (fMWCNTs) nanocomposite was prepared on the glassy carbon electrode (GCE) by a facile one-step electrochemical polymerization technique followed by chitosan-glucose oxidase (CH-GOx) immobilization on its surface to achieve a high-performance glucose biosensor. The as-fabricated nanohybrid composite provides high surface area for GOx immobilization and thus enhances the enzyme-loading efficiency. The structural characterization revealed that the PPy-Nf-fMWCNTs nanocomposite films were uniformly formed on GCE and after GOx immobilization, the surface porosities of the film were decreased due to enzyme encapsulation inside the bio-nanohybrid composite materials. The electrochemical behavior of the fabricated biosensor was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry measurements. The results indicated an excellent catalytic property of bio-nanohybrid film for glucose detection with improved sensitivity of 2860.3μAmM(-1)cm(-2), the linear range up to 4.7mM (R(2)=0.9992), and a low detection limit of 5μM under a signal/noise (S/N) ratio of 3. Furthermore, the resulting biosensor presented reliable selectivity, better long-term stability, good repeatability, reproducibility, and acceptable measurement of glucose concentration in real serum samples. Thus, this fabricated biosensor provides an efficient and highly sensitive platform for glucose sensing and can open up new avenues for clinical applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. High isostatic pressure and thermal processing of açaí fruit (Euterpe oleracea Martius): Effect on pulp color and inactivation of peroxidase and polyphenol oxidase.

    Science.gov (United States)

    Jesus, Ana Laura Tibério de; Leite, Thiago Soares; Cristianini, Marcelo

    2018-03-01

    The present study evaluated the effect of high isostatic pressure (HIP) on the activity of peroxidase (POD) and polyphenol oxidase (PPO) from açaí. Açaí pulp was submitted to several combinations of pressure (400, 500, 600MPa), temperature (25 and 65°C) for 5 and 15min. The combined effect of HIP technology and high temperatures (690MPa by 2 and 5min at 80°C) was also investigated and compared to the conventional thermal treatment (85°C/1min). POD and PPO enzyme activity and instrumental color were examined after processing and after 24h of refrigerated storage. Results showed stability of POD for all pressures at 25°C, which proved to be heat-resistant and baro-resistant at 65°C. For PPO, the inactivation at 65°C was 71.7% for 600MPa after 15min. In general, the increase in temperature from 25°C to 65°C reduced the PPO relative activity with no changes in color. Although the thermal treatment and the HIP (690MPa) along with high temperature (80°C) reduced the PPO relative activity, and relevant darkening was observed in the processed samples. Thus, it can be concluded that POD is more baro-resistant than PPO in açaí pulp subjected to the same HIP processing conditions and processing at 600MPa/65°C for 5min may be an effective alternative for thermal pasteurization treatments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The immobilisation of trypsin and glucose oxidase onto natural rubber-g.co-HEMA - high energy radiation derived copolymeric support systems

    International Nuclear Information System (INIS)

    Devi, S.; Guthrie, J.T.; Beddows, C.G.

    1990-01-01

    Natural rubber has been grafted with 2-HEMA by three different methods each involving Co(60)γ-radiation as the initiation source. The grafted samples were used in the immobilisation of glucose oxidase and trypsin. Optimisation of immobilisation involving trypsin was studied with regard to the pH and the type of crosslinking agent. It was observed that the immobilised enzyme had superior stability over a wider pH range when compared to the free trypsin. The retention of activity demonstrated by the immobilised trypsin was significant. That of immobilised glucose oxidase was far from being satisfactory. (author)

  2. Studying neuroprotective effect of Atorvastatin as a small molecule drug on high glucose-induced neurotoxicity in undifferentiated PC12 cells: role of NADPH oxidase.

    Science.gov (United States)

    Rayegan, Samira; Dehpour, Ahmad Reza; Sharifi, Ali Mohammad

    2017-02-01

    Overproduction of reactive oxygen species (ROS) by NADPH oxidase (NOX) activation has been considered the essential mechanism induced by hyperglycemia in various tissues. However, there is no comprehensive study on the role of NOXs in high glucose (HG)-induced toxic effect in neural tissues. Recently, a therapeutic strategy in oxidative related pathologies has been introduced by blocking the undesirable actions of NOX enzymes by small molecules. The protective roles of Statins in ameliorating oxidative stress by NOX inhibition have been shown in some tissues except neural. We hypothesized then, that different NOXs may have role in HG-induced neural cell injury. Furthermore, we postulate that Atorvastatin as a small molecule may modulate this NOXs activity to protect neural cells. Undifferentiated PC12 cells were treated with HG (140 mM/24 h) in the presence and absence of Atorvastatin (1 μM/96 h). The cell viability was measured by MTT assay and the gene and protein expressions profile of NOX (1-4) were determined by RT-PCR and western blotting, respectively. Levels of ROS and malondialdehyde (MDA) were also evaluated. Gene and protein expression levels of NOX (1-4) and consequently ROS and MDA levels were elevated in HG-treated PC12 cells. Atorvastatin could significantly decrease HG-induced NOXs, ROS and MDA elevation and improve impaired cell viability. It can be concluded that HG could elevate NOXs activity, ROS and MDA levels in neural tissues and Atorvastatin as a small molecule NOX inhibitor drug may prevent and delay diabetic complications, particularly neuropathy.

  3. Symbiotic Burkholderia Species Show Diverse Arrangements of nif/fix and nod Genes and Lack Typical High-Affinity Cytochrome cbb3 Oxidase Genes.

    Science.gov (United States)

    De Meyer, Sofie E; Briscoe, Leah; Martínez-Hidalgo, Pilar; Agapakis, Christina M; de-Los Santos, Paulina Estrada; Seshadri, Rekha; Reeve, Wayne; Weinstock, George; O'Hara, Graham; Howieson, John G; Hirsch, Ann M

    2016-08-01

    Genome analysis of fourteen mimosoid and four papilionoid beta-rhizobia together with fourteen reference alpha-rhizobia for both nodulation (nod) and nitrogen-fixing (nif/fix) genes has shown phylogenetic congruence between 16S rRNA/MLSA (combined 16S rRNA gene sequencing and multilocus sequence analysis) and nif/fix genes, indicating a free-living diazotrophic ancestry of the beta-rhizobia. However, deeper genomic analysis revealed a complex symbiosis acquisition history in the beta-rhizobia that clearly separates the mimosoid and papilionoid nodulating groups. Mimosoid-nodulating beta-rhizobia have nod genes tightly clustered in the nodBCIJHASU operon, whereas papilionoid-nodulating Burkholderia have nodUSDABC and nodIJ genes, although their arrangement is not canonical because the nod genes are subdivided by the insertion of nif and other genes. Furthermore, the papilionoid Burkholderia spp. contain duplications of several nod and nif genes. The Burkholderia nifHDKEN and fixABC genes are very closely related to those found in free-living diazotrophs. In contrast, nifA is highly divergent between both groups, but the papilionoid species nifA is more similar to alpha-rhizobia nifA than to other groups. Surprisingly, for all Burkholderia, the fixNOQP and fixGHIS genes required for cbb3 cytochrome oxidase production and assembly are missing. In contrast, symbiotic Cupriavidus strains have fixNOQPGHIS genes, revealing a divergence in the evolution of two distinct electron transport chains required for nitrogen fixation within the beta-rhizobia.

  4. Novel phenotypes of pyridox(am)ine-5'-phosphate oxidase deficiency and high prevalence of c.445_448del mutation in Chinese patients.

    Science.gov (United States)

    Xue, Jiao; Chang, Xingzhi; Zhang, Yuehua; Yang, Zhixian

    2017-08-01

    To analyze the clinical and genetic characteristics of Chinese patients with pyridox(am)ine-5'-phosphate oxidase (PNPO) deficiency. The clinical presentations and the responses to treatments were analyzed in 4 patients. Blood and urinary metabolic screenings, electroencephalogram (EEG), brain magnetic resonance imaging (MRI) and epilepsy-related genes detection were performed in all patients. Patient 1 and 2 were identical twin brothers, who were born at 35 +5 w gestation with a sign of encephalopathy. Their seizures started within the first day and could not be controlled by pyridoxine or pyridoxal-5'-phosphate (PLP) completely. Patient 3 presented seizures at 5 months, responding well to pyridoxine. Seizures in patient 4 began at 40 days after birth and were controlled by valproic acid and topiramate. EEG showed atypical hypsarrhythmia or multifocal epileptiform discharges in 3 patients, and showed normality in patient 4. MRI showed nonspecific abnormality or normality. Blood metabolic screening showed multiple amino acids level abnormalities in all cases. Urinary metabolic screening showed vanillactic acid prominently elevated in 3 patients. Genetic analysis revealed 5 mutations of PNPO, three of which were novel. The mutation c.445_448del was carried by the twins and patient 3. Assessment of psychomotor development indicated severe delay in 3 patients and borderline to mild delay in patient 3. This is the first time to report patients with PNPO deficiency diagnosed by gene analysis in China. The novel clinical characteristics and novel mutations found here expanded the phenotypes and genotypes of this disease. Further, the frameshift mutation c.445_448del might be high prevalence in PNPO deficiency in Chinese patients.

  5. Reduced graphene oxide–cuprous oxide composite via facial deposition for photocatalytic dye-degradation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, MingYan, E-mail: mingyanlyg@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Huang, JunRao; Tong, ZhiWei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Li, WeiHua [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Chen, Jun, E-mail: junc@uow.edu.au [Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2013-08-15

    Highlights: •Cubic Cu{sub 2}O were effectively loaded on n-propylamine (PA) intercalated graphene oxide. •The addition of PA on the carbon sheets supports the stable structure of the composites. •Cu{sub 2}O/PA/rGO showed superior adsorption capacity and photocatalytic activity. -- Abstract: Cubic Cu{sub 2}O nanoparticles have been successfully synthesized on n-propylamine (PA) intercalated graphene oxide (GO) with uniform distribution followed with a subsequent hydrazine hydrate reduction process to generate Cu{sub 2}O/PA/rGO composite. For comparison, Cu{sub 2}O conjugated reduced graphene oxide (Cu{sub 2}O/rGO) composite was also synthesized using the same method. The as-prepared Cu{sub 2}O/PA/rGO and Cu{sub 2}O/rGO nanocomposites are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Electrochemical impedance spectra (EIS) measurements. UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of cuprous oxide composites. The results show that the intercalation of PA into the layered GO increases the surface area of the composites and provides an efficient strategy to load Cu{sub 2}O due to the large and uniform distribution of active sites for anchoring copper ions. The surface area of the Cu{sub 2}O/PA/rGO (123 m{sup 2}/g) nanocomposite was found to be almost 2.5 times higher than that of Cu{sub 2}O/rGO (55.7 m{sup 2}/g). The as-prepared Cu{sub 2}O/PA/rGO show significant improvement on both adsorption capacity and photocatalytic activity towards organic pigment pollution compared with Cu{sub 2}O/rGO under identical performance conditions.

  6. Identification of aldehyde oxidase 1 and aldehyde oxidase homologue 1 as dioxin-inducible genes

    International Nuclear Information System (INIS)

    Rivera, Steven P.; Choi, Hyun Ho; Chapman, Brett; Whitekus, Michael J.; Terao, Mineko; Garattini, Enrico; Hankinson, Oliver

    2005-01-01

    Aldehyde oxidases are a family of highly related molybdo-flavoenzymes acting upon a variety of compounds of industrial and medical importance. We have identified aldehyde oxidase 1 (AOX1) as a 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) inducible gene in the mouse hepatoma cell line Hepa-1. AOX1 mRNA levels were not increased by dioxin in mutant derivatives of the Hepa-1 cell line lacking either functional aryl hydrocarbon receptor (AHR) or aryl hydrocarbon receptor nuclear translocator (ARNT) proteins, thus demonstrating that transcriptional induction of AOX1 in response to dioxin occurs through the AHR pathway. Dioxin induction of AOX1 mRNA was also observed in mouse liver. In addition, levels of AOX1 protein as well as those of aldehyde oxidase homologue 1 (AOH1), a recently identified homolog of AOX1, were elevated in mouse liver in response to dioxin. Employing an aldehyde oxidase specific substrate, AOX1/AOH1 activity was shown to be induced by dioxin in mouse liver. This activity was inhibited by a known inhibitor of aldehyde oxidases, and eliminated by including tungstate in the mouse diet, which is known to lead to inactivation of molybdoflavoenzymes, thus confirming that the enzymatic activity was attributable to AOX1/AOH1. Our observations thus identify two additional xenobiotic metabolizing enzymes induced by dioxin

  7. Oxidase-based biocatalytic processes

    DEFF Research Database (Denmark)

    Ramesh, Hemalata; Woodley, John; Krühne, Ulrich

    interestingbiocatalystsbecause they use a mild oxidant (oxygen) as a substrateas opposed to their chemical counterparts which use strong oxidants such as permanganates. A class of oxidases calledmonoamine oxidases has been used as the central case study for the thesis. The rationale for choosing thissystemis that it has been...

  8. Effects of glucose oxidase on the growth performance, serum ...

    African Journals Online (AJOL)

    Martina

    2016-02-06

    Feb 6, 2016 ... The experiment was conducted to investigate the effects of diets supplemented with ... Keywords: Glucose oxidase, intestinal health, performance, swine ..... This work was supported by the National High-Tech Research and ...

  9. An Oxidase-Based Electrochemical Fluidic Sensor with High-Sensitivity and Low-Interference by On-Chip Oxygen Manipulation

    Directory of Open Access Journals (Sweden)

    Chang-Soo Kim

    2012-06-01

    Full Text Available Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide. Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc. to implement a viable component for in-line fluidic sensor systems.

  10. Platelet monoamine oxidase: specific activity and turnover number in headache

    International Nuclear Information System (INIS)

    Summers, K.M.; Brown, G.K.; Craig, I.W.; Peatfield, R.; Rose, F.C.

    1982-01-01

    Monoamine oxidase turnover numbers (molecules of substrate converted to product per minute per active site) have been calculated for the human platelet enzyme using [ 3 H]pargyline. Headache patients with high and low monoamine oxidase specific activities relative to controls were found to have turnover numbers very close to those for controls. This finding suggests that their specific activities vary because of differences in the concentration of active monoamine oxidase molecules, rather than differences in the ability of those enzyme molecules to catalyse the deamination reaction. (Auth.)

  11. Electrical bistability and charge-transport mechanisms in cuprous sulfide nanosphere-poly(N-vinylcarbazole) composite films

    International Nuclear Information System (INIS)

    Tang Aiwei; Teng Feng; Liu Jie; Wang Yichao; Peng Hongshang; Hou Yanbing; Wang Yongsheng

    2011-01-01

    In this study, electrically bistable devices were fabricated by incorporating cuprous sulfide (Cu 2 S) nanospheres with mean size less than 10 nm into a poly(N-vinylcarbazole) (PVK) matrix. A remarkable electrical bistability was clearly observed in the current–voltage curves of the devices due to an electric-field-induced charge transfer between the dodecanethiol-capped Cu 2 S nanospheres and PVK. The maximum ON/OFF current ratio reached up to value as large as 10 4 , which was dependent on the mass ratios of Cu 2 S nanospheres to PVK, the amplitude of the scanning voltages, and the film thickness. The charge-transport mechanisms of the electrically bistable devices were described on the basis of the experimental results using different theoretical models of organic electronics.

  12. Evaluation of oxalate decarboxylase and oxalate oxidase for industrial applications.

    Science.gov (United States)

    Cassland, Pierre; Sjöde, Anders; Winestrand, Sandra; Jönsson, Leif J; Nilvebrant, Nils-Olof

    2010-05-01

    Increased recirculation of process water has given rise to problems with formation of calcium oxalate incrusts (scaling) in the pulp and paper industry and in forest biorefineries. The potential in using oxalate decarboxylase from Aspergillus niger for oxalic acid removal in industrial bleaching plant filtrates containing oxalic acid was examined and compared with barley oxalate oxidase. Ten different filtrates from chemical pulping were selected for the evaluation. Oxalate decarboxylase degraded oxalic acid faster than oxalate oxidase in eight of the filtrates, while oxalate oxidase performed better in one filtrate. One of the filtrates inhibited both enzymes. The potential inhibitory effect of selected compounds on the enzymatic activity was tested. Oxalate decarboxylase was more sensitive than oxalate oxidase to hydrogen peroxide. Oxalate decarboxylase was not as sensitive to chlorate and chlorite as oxalate oxidase. Up to 4 mM chlorate ions, the highest concentration tested, had no inhibitory effect on oxalate decarboxylase. Analysis of the filtrates suggests that high concentrations of chlorate present in some of the filtrates were responsible for the higher sensitivity of oxalate oxidase in these filtrates. Oxalate decarboxylase was thus a better choice than oxalate oxidase for treatment of filtrates from chlorine dioxide bleaching.

  13. Production of rabbit antibodies against purified Glucose oxidase

    OpenAIRE

    Zia,Muhammad Anjum; Ain,Qurat-ul; Iftikhar,Tehreema; Abbas,Rao Zahid; Rahman,Khalil-ur

    2012-01-01

    Glucose oxidase is an active oxygen species generating enzyme produced from Aspergillus niger grown in submerged fermentation. Disintegration of the mycelium resulted in high glucose oxidase activity that was subjected to ammonium sulfate precipitation at 60-85% saturation rates that resulted to 6.14 U mg -1 specific activity. Purification of enzyme by anion exchange column (DEAE-Cellulose) resulted into 22.53 U mg-1 specific activity and 10.27 fold purification. This was applied to sephadex ...

  14. Oxidases as Breast Cancer Oncogens

    National Research Council Canada - National Science Library

    Yeldandi, Anjana

    2000-01-01

    ...) in a non-tumorigenic human mammary epithelial cell line to ascertain whether oxidase overexpressing cells undergo transformation when exposed to substrate xanthine for XOX and uric acid for UOX...

  15. Glucose oxidase variants with improved properities

    OpenAIRE

    Fischer, Rainer; Ostafe, Raluca; Prodanovic, Radivoje

    2014-01-01

    Source: WO14173822A3 [EN] The technology provided herein relates to novel variants of microbial glucose oxidase with improved properties, more specifically to polypeptides having glucose oxidase activity as their major enzymatic activity; to nucleic acid molecules encoding said glucose oxidases; vectors and host cells containing the nucleic acids and methods for producing the glucose oxidase; compositions comprising said glucose oxidase; methods for the preparation and production of such enzy...

  16. NADPH Oxidases: Progress and Opportunities

    OpenAIRE

    San Martin, Alejandra; Griendling, Kathy K.

    2014-01-01

    From the initial discovery in 1999 that NADPH oxidases comprise a family of enzymes to our current focus on drug development to treat multiple pathologies related to this enzyme family, progress has been swift and impressive. We have expanded our understanding of the extent of the family, the basic enzymatic biochemistry, the multiple cellular functions controlled by NADPH oxidases, and their varied roles in physiology and diseases. We have developed numerous cell culture tools, animal models...

  17. Plasma diamine oxidase activity in asthmatic children

    Directory of Open Access Journals (Sweden)

    Kyoichiro Toyoshima

    1996-01-01

    Full Text Available Histamine plays an important role in the development of asthmatic symptoms. Diamine oxidase (DAO histaminase, which inactivates histamine, is located in the intestine and kidney and is released into plasma. Plasma DAO activity in asthmatic children was measured by a recently developed high performance liquid chromatographic method using histamine as the DAO substrate. Diamine oxidase activity was higher in severely asthmatic children than in those with mild asthma. A time course study during the acute exacerbation phase revealed that DAO activity rose during acute asthmatic attacks and then decreased gradually over several days. Although the mechanisms of plasma DAO activity increase during acute asthmatic attacks could not be explained, data showed that plasma DAO activity is an important index of histamine metabolism in asthmatics and may relate to some mechanisms of acute exacerbation of airway inflammation. Consequently, fluctuations in plasma DAO can be used as one of various indices of instability in management of asthma.

  18. Covalently bound phosphate residues in bovine milk xanthine oxidase and in glucose oxidase from Aspergillus niger: A reevaluation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J.L.; Rajagopalan, K.V. (Duke Univ. Medical Center, Durham, NC (USA)); London, R.E. (National Institute of Environmental Health Science, Research Triangle Park, NC (USA))

    1989-09-01

    The reported presence of covalently bound phosphate residues in flavoproteins has significant implications with regard to the catalytic mechanisms and structural stability of the specific enzymes themselves and in terms of general cellular metabolic regulation. These considerations have led to a reevaluation of the presence of covalently bound phosphorus in the flavoproteins xanthine oxidase and glucose oxidase. Milk xanthine oxidase purified by a procedure that includes anion-exchange chromatography is shown to contain three phosphate residues. All three are noncovalently associated with the protein, two with the FAD cofactor, and one with the molybdenum cofactor. Results of chemical analysis and {sup 31}P NMR spectroscopy indicate that enzyme purified by this method contains no phosphoserine residues. Xanthine oxidase preparations purified by chromatography on calcium phosphate gel in place of DEAE-Sephadex yielded higher phosphate-to-protein ratios, which could be reduced to the expected values by additional purification on a folate affinity column. Highly active, highly purified preparations of glucose oxidase are shown to contain only the two phosphate residues of the FAD cofactor. The covalently bound bridging phosphate reported by others may arise in aged or degraded preparations of the enzyme but appears not to be a constituent of functional glucose oxidase. These results suggest that the presence of covalent phosphate residues in other flavoproteins should be rigorously reevaluated as well.

  19. Covalently bound phosphate residues in bovine milk xanthine oxidase and in glucose oxidase from Aspergillus niger: A reevaluation

    International Nuclear Information System (INIS)

    Johnson, J.L.; Rajagopalan, K.V.; London, R.E.

    1989-01-01

    The reported presence of covalently bound phosphate residues in flavoproteins has significant implications with regard to the catalytic mechanisms and structural stability of the specific enzymes themselves and in terms of general cellular metabolic regulation. These considerations have led to a reevaluation of the presence of covalently bound phosphorus in the flavoproteins xanthine oxidase and glucose oxidase. Milk xanthine oxidase purified by a procedure that includes anion-exchange chromatography is shown to contain three phosphate residues. All three are noncovalently associated with the protein, two with the FAD cofactor, and one with the molybdenum cofactor. Results of chemical analysis and 31 P NMR spectroscopy indicate that enzyme purified by this method contains no phosphoserine residues. Xanthine oxidase preparations purified by chromatography on calcium phosphate gel in place of DEAE-Sephadex yielded higher phosphate-to-protein ratios, which could be reduced to the expected values by additional purification on a folate affinity column. Highly active, highly purified preparations of glucose oxidase are shown to contain only the two phosphate residues of the FAD cofactor. The covalently bound bridging phosphate reported by others may arise in aged or degraded preparations of the enzyme but appears not to be a constituent of functional glucose oxidase. These results suggest that the presence of covalent phosphate residues in other flavoproteins should be rigorously reevaluated as well

  20. Promoter isolation and characterization of GhAO-like1, a Gossypium hirsutum gene similar to multicopper oxidases that is highly expressed in reproductive organs.

    Science.gov (United States)

    Lambret-Frotté, Julia; Artico, Sinara; Muniz Nardeli, Sarah; Fonseca, Fernando; Brilhante Oliveira-Neto, Osmundo; Grossi-de-Sá, Maria Fatima; Alves-Ferreira, Marcio

    2016-01-01

    Cotton is one of the most economically important cultivated crops. It is the major source of natural fiber for the textile industry and an important target for genetic modification for both biotic stress and herbicide tolerance. Therefore, the characterization of genes and regulatory regions that might be useful for genetic transformation is indispensable. The isolation and characterization of new regulatory regions is of great importance to drive transgene expression in genetically modified crops. One of the major drawbacks in cotton production is pest damage; therefore, the most promising, cost-effective, and sustainable method for pest control is the development of genetically resistant cotton lines. Considering this scenario, our group isolated and characterized the promoter region of a MCO (multicopper oxidase) from Gossypium hirsutum, named GhAO-like1 (ascorbate oxidase-like1). The quantitative expression, together with the in vivo characterization of the promoter region reveals that GhAO-like1 has a flower- and fruit-specific expression pattern. The GUS activity is mainly observed in stamens, as expected considering that the GhAO-like1 regulatory sequence is enriched in cis elements, which have been characterized as a target of reproductive tissue specific transcription factors. Both histological and quantitative analyses in Arabidopsis thaliana have confirmed flower (mainly in stamens) and fruit expression of GhAO-like1. In the present paper, we isolated and characterized both in silico and in vivo the promoter region of the GhAO-like1 gene. The regulatory region of GhAO-like1 might be useful to confer tissue-specific expression in genetically modified plants.

  1. Preparation, characterization and nonlinear absorption studies of cuprous oxide nanoclusters, micro-cubes and micro-particles

    Science.gov (United States)

    Sekhar, H.; Narayana Rao, D.

    2012-07-01

    Cuprous oxide nanoclusters, micro-cubes and micro-particles were successfully synthesized by reducing copper(II) salt with ascorbic acid in the presence of sodium hydroxide via a co-precipitation method. The X-ray diffraction and FTIR studies revealed that the formation of pure single-phase cubic. Raman and EPR spectral studies show the presence of CuO in as-synthesized powders of Cu2O. Transmission electron microscopy and field emission scanning electron microscopy data revealed that the morphology evolves from nanoclusters to micro-cubes and micro-particles by increasing the concentration of NaOH. Linear optical measurements show absorption peak maximum shifts towards red with changing morphology from nanoclusters to micro-cubes and micro-particles. The nonlinear optical properties were studied using open aperture Z-scan technique with 532 nm 6 ns laser pulses. Samples-exhibited both saturable as well as reverse saturable absorption. Due to confinement effects (enhanced band gap), we observed enhanced nonlinear absorption coefficient (β) in the case of nanoclusters compared to their micro-cubes and micro-particles.

  2. Effect of cuprous halide interlayers on the device performance of ZnPc/C{sub 60} organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jinho; Park, Dasom; Heo, Ilsu; Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr

    2014-10-15

    Highlights: • Effect of CuX interlayers on subsequently deposited films and devices was studied. • CuI is the most effective for the performance of ZnPc/C{sub 60}-based solar cells. • Results were related to the molecular geometry of ZnPc and HOMO level of interlayers. - Abstract: The effect of various cuprous halide (CuX) interlayers introduced between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) layer and zinc phthalocyanine (ZnPc) layer on the physical properties of the ZnPc thin films and device performances of ZnPc/C{sub 60}-based small-molecule organic solar cells was studied. Strong substrate–molecule interaction between the CuX and ZnPc partly converted surface-perpendicular stacking geometry of ZnPc molecules into surface-parallel one. This flat-lying geometry led to an enhancement in electronic absorption and charge transport within the ZnPc films. As a result, the overall power conversion efficiency of the cell with CuI interlayer increased by ∼37%. In the case of the cells with CuBr and CuCl interlayer, however, the enhancement in device performances was limited because of the reduced conversion of the molecular geometry and increased energy barrier for hole extraction due to the low highest occupied molecular orbital level of the interlayer.

  3. Effect of cuprous halide interlayers on the device performance of ZnPc/C60 organic solar cells

    International Nuclear Information System (INIS)

    Lee, Jinho; Park, Dasom; Heo, Ilsu; Yim, Sanggyu

    2014-01-01

    Highlights: • Effect of CuX interlayers on subsequently deposited films and devices was studied. • CuI is the most effective for the performance of ZnPc/C 60 -based solar cells. • Results were related to the molecular geometry of ZnPc and HOMO level of interlayers. - Abstract: The effect of various cuprous halide (CuX) interlayers introduced between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) layer and zinc phthalocyanine (ZnPc) layer on the physical properties of the ZnPc thin films and device performances of ZnPc/C 60 -based small-molecule organic solar cells was studied. Strong substrate–molecule interaction between the CuX and ZnPc partly converted surface-perpendicular stacking geometry of ZnPc molecules into surface-parallel one. This flat-lying geometry led to an enhancement in electronic absorption and charge transport within the ZnPc films. As a result, the overall power conversion efficiency of the cell with CuI interlayer increased by ∼37%. In the case of the cells with CuBr and CuCl interlayer, however, the enhancement in device performances was limited because of the reduced conversion of the molecular geometry and increased energy barrier for hole extraction due to the low highest occupied molecular orbital level of the interlayer

  4. Lysyl oxidase in colorectal cancer

    DEFF Research Database (Denmark)

    Cox, Thomas R; Erler, Janine T

    2013-01-01

    Colorectal cancer is the third most prevalent form of cancer worldwide and fourth-leading cause of cancer-related mortality, leading to ~600,000 deaths annually, predominantly affecting the developed world. Lysyl oxidase is a secreted, extracellular matrix-modifying enzyme previously suggested...... to act as a tumor suppressor in colorectal cancer. However, emerging evidence has rapidly implicated lysyl oxidase in promoting metastasis of solid tumors and in particular colorectal cancer at multiple stages, affecting tumor cell proliferation, invasion, and angiogenesis. This emerging research has...... advancements in the field of colorectal cancer....

  5. DL-3-n-butylphthalide-Edaravone hybrids as novel dual inhibitors of amyloid-β aggregation and monoamine oxidases with high antioxidant potency for Alzheimer's therapy.

    Science.gov (United States)

    Qiang, Xiaoming; Li, Yan; Yang, Xia; Luo, Li; Xu, Rui; Zheng, Yunxiaozhu; Cao, Zhongcheng; Tan, Zhenghuai; Deng, Yong

    2017-02-15

    Considering the complex etiology of Alzheimer's disease (AD), multifunctional agents may be beneficial for the treatment of this disease. A series of DL-3-n-butylphthalide-Edaravone hybrids were designed, synthesized and evaluated as novel dual inhibitors of amyloid-β aggregation and monoamine oxidases. Among them, compounds 9a-d exhibited good inhibition of self-induced Aβ 1-42 aggregation with inhibition ratio 57.7-71.5%. For MAO, these new hybrids exhibited good balance of inhibition for MAO-A and MAO-B. In addition, all target compounds retained the antioxidant activity of edaravone, showed equal or better antioxidant activity than edaravone. The results of the parallel artificial membrane permeability assay for blood-brain barrier indicated that compounds 9a-d would be able to cross the blood-brain barrier and reach their biological targets in the central nervous system. The promising results in all assays demonstrated that the strategy behind the designing of compounds was rational and favourable. Taken together, these preliminary findings suggested that the compounds with the strongest bioactivity deserves further investigated for pharmacological development in AD therapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Benfotiamine increases glucose oxidation and downregulates NADPH oxidase 4 expression in cultured human myotubes exposed to both normal and high glucose concentrations.

    Science.gov (United States)

    Fraser, D A; Hessvik, N P; Nikolić, N; Aas, V; Hanssen, K F; Bøhn, S K; Thoresen, G H; Rustan, A C

    2012-07-01

    The aim of the present work was to study the effects of benfotiamine (S-benzoylthiamine O-monophosphate) on glucose and lipid metabolism and gene expression in differentiated human skeletal muscle cells (myotubes) incubated for 4 days under normal (5.5 mM glucose) and hyperglycemic (20 mM glucose) conditions. Myotubes established from lean, healthy volunteers were treated with benfotiamine for 4 days. Glucose and lipid metabolism were studied with labeled precursors. Gene expression was measured using real-time polymerase chain reaction (qPCR) and microarray technology. Benfotiamine significantly increased glucose oxidation under normoglycemic (35 and 49% increase at 100 and 200 μM benfotiamine, respectively) as well as hyperglycemic conditions (70% increase at 200 μM benfotiamine). Benfotiamine also increased glucose uptake. In comparison, thiamine (200 μM) increased overall glucose metabolism but did not change glucose oxidation. In contrast to glucose, mitochondrial lipid oxidation and overall lipid metabolism were unchanged by benfotiamine. The expression of NADPH oxidase 4 (NOX4) was significantly downregulated by benfotiamine treatment under both normo- and hyperglycemic conditions. Gene set enrichment analysis (GSEA) showed that befotiamine increased peroxisomal lipid oxidation and organelle (mitochondrial) membrane function. In conclusion, benfotiamine increases mitochondrial glucose oxidation in myotubes and downregulates NOX4 expression. These findings may be of relevance to type 2 diabetes where reversal of reduced glucose oxidation and mitochondrial capacity is a desirable goal.

  7. Lysyl oxidase in cancer research

    DEFF Research Database (Denmark)

    Perryman, Lara; Erler, Janine Terra

    2014-01-01

    Metastasis is the main reason for cancer-associated deaths and therapies are desperately needed to target the progression of cancer. Lysyl oxidase (LOX) plays a pivotal role in cancer progression, including metastasis, and is therefore is an attractive therapeutic target. In this review we...

  8. Characterization of wheat germin (oxalate oxidase) expressed by Pichia pastoris

    International Nuclear Information System (INIS)

    Pan, Heng-Yen; Whittaker, Mei M.; Bouveret, Romaric; Berna, Anne; Bernier, Francois; Whittaker, James W.

    2007-01-01

    High-level secretory expression of wheat (Triticum aestivum) germin/oxalate oxidase was achieved in Pichia pastoris fermentation cultures as an α-mating factor signal peptide fusion, based on the native wheat cDNA coding sequence. The oxalate oxidase activity of the recombinant enzyme is substantially increased (7-fold) by treatment with sodium periodate, followed by ascorbate reduction. Using these methods, approximately 1 g (4 x 10 4 U) of purified, activated enzyme was obtained following eight days of induction of a high density Pichia fermentation culture, demonstrating suitability for large-scale production of oxalate oxidase for biotechnological applications. Characterization of the recombinant protein shows that it is glycosylated, with N-linked glycan attached at Asn47. For potential biomedical applications, a nonglycosylated (S49A) variant was also prepared which retains essentially full enzyme activity, but exhibits altered protein-protein interactions

  9. Hot or not? Discovery and characterization of a thermostable alditol oxidase from Acidothermus cellulolyticus 11B

    NARCIS (Netherlands)

    Winter, Remko T.; Heuts, Dominic P. H. M.; Rijpkema, Egon M. A.; van Bloois, Edwin; Wijma, Hein J.; Fraaije, Marco W.

    We describe the discovery, isolation and characterization of a highly thermostable alditol oxidase from Acidothermus cellulolyticus 11B. This protein was identified by searching the genomes of known thermophiles for enzymes homologous to Streptomyces coelicolor A3(2) alditol oxidase (AldO). A gene

  10. Discovery, characterization, and kinetic analysis of an alditol oxidase from streptomyces coelicolor

    NARCIS (Netherlands)

    Heuts, Dominic P. H. M.; van Hellemond, Erik W.; Janssen, Dick B.; Fraaije, Marco W.

    2007-01-01

    A gene encoding an alditol oxidase was found in the genome of Streptomyces coelicolor A3(2). This newly identified oxidase, AldO, was expressed at extremely high levels in Escherichia coli when fused to maltose-binding protein. AldO is a soluble monomeric flavoprotein with subunits of 45.1 kDa, each

  11. Xanthine oxidase functionalized Ta2O5 nanostructures as a novel scaffold for highly sensitive SPR based fiber optic xanthine sensor.

    Science.gov (United States)

    Kant, Ravi; Tabassum, Rana; Gupta, Banshi D

    2018-01-15

    Fabrication and characterization of a surface plasmon resonance based fiber optic xanthine sensor using entrapment of xanthine oxidase (XO) enzyme in several nanostructures of tantalum (v) oxide (Ta 2 O 5 ) have been reported. Chemical route was adopted for synthesizing Ta 2 O 5 nanoparticles, nanorods, nanotubes and nanowires while Ta 2 O 5 nanofibers were prepared by electrospinning technique. The synthesized Ta 2 O 5 nanostructures were characterized by photoluminescence, scanning electron microscopy, UV-Visible spectra and X-ray diffraction pattern. The probes were fabricated by coating an unclad core of the fiber with silver layer followed by the deposition of XO entrapped Ta 2 O 5 nanostructures. The crux of sensing mechanism relies on the modification of dielectric function of sensing layer upon exposure to xanthine solution of diverse concentrations, reflected in terms of shift in resonance wavelength. The sensing probe coated with XO entrapped Ta 2 O 5 nanofibers has been turned out to possess maximum sensitivity amongst the synthesized nanostructures. The probe was optimized in terms of pH of the sample and the concentration of XO entrapped in Ta 2 O 5 nanofibers. The optimized sensing probe possesses a remarkably good sensitivity of 26.2nm/µM in addition to linear range from 0 to 3µM with an invincible LOD value of 0.0127µM together with a response time of 1min. Furthermore, probe selectivity with real sample analysis ensure the usage of the sensor for practical scenario. The results reported open a novel perspective towards a sensitive, rapid, reliable and selective detection of xanthine. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Production of rabbit antibodies against purified Glucose oxidase

    Directory of Open Access Journals (Sweden)

    Muhammad Anjum Zia

    2012-02-01

    Full Text Available Glucose oxidase is an active oxygen species generating enzyme produced from Aspergillus niger grown in submerged fermentation. Disintegration of the mycelium resulted in high glucose oxidase activity that was subjected to ammonium sulfate precipitation at 60-85% saturation rates that resulted to 6.14 U mg -1 specific activity. Purification of enzyme by anion exchange column (DEAE-Cellulose resulted into 22.53 U mg-1 specific activity and 10.27 fold purification. This was applied to sephadex G-200 column for gel filtration chromatography. It was observed that enzyme achieved 59.37 U mg-1of specific activity with 27.08 fold purity and 64.36% recovery. Purified glucose oxidase was injected into rabbits through intravenous route, to raise the glucose oxidase antibodies. After 30 days incubation period, the rabbits were slaughtered and serum was separated from blood. The antibodies were isolated by ammonium sulfate precipitation and confirmed by agar gel precipitation test. This could be a convenient and low cost alternate assay for the estimation of glucose oxidase in biological fluids. Moreover, such antibodies against the said enzyme could be used in various therapeutic and diagnostic applications.

  13. Putting together a plasma membrane NADH oxidase: a tale of three laboratories.

    Science.gov (United States)

    Löw, Hans; Crane, Frederick L; Morré, D James

    2012-11-01

    The observation that high cellular concentrations of NADH were associated with low adenylate cyclase activity led to a search for the mechanism of the effect. Since cyclase is in the plasma membrane, we considered the membrane might have a site for NADH action, and that NADH might be oxidized at that site. A test for NADH oxidase showed very low activity, which could be increased by adding growth factors. The plasma membrane oxidase was not inhibited by inhibitors of mitochondrial NADH oxidase such as cyanide, rotenone or antimycin. Stimulation of the plasma membrane oxidase by iso-proterenol or triiodothyronine was different from lack of stimulation in endoplasmic reticulum. After 25 years of research, three components of a trans membrane NADH oxidase have been discovered. Flavoprotein NADH coenzyme Q reductases (NADH cytochrome b reductase) on the inside, coenzyme Q in the middle, and a coenzyme Q oxidase on the outside as a terminal oxidase. The external oxidase segment is a copper protein with unique properties in timekeeping, protein disulfide isomerase and endogenous NADH oxidase activity, which affords a mechanism for control of cell growth by the overall NADH oxidase and the remarkable inhibition of oxidase activity and growth of cancer cells by a wide range of anti-tumor drugs. A second trans plasma membrane electron transport system has been found in voltage dependent anion channel (VDAC), which has NADH ferricyanide reductase activity. This activity must be considered in relation to ferricyanide stimulation of growth and increased VDAC antibodies in patients with autism. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Low temperature (< 100 °C) deposited P-type cuprous oxide thin films: Importance of controlled oxygen and deposition energy

    International Nuclear Information System (INIS)

    Li, Flora M.; Waddingham, Rob; Milne, William I.; Flewitt, Andrew J.; Speakman, Stuart; Dutson, James; Wakeham, Steve; Thwaites, Mike

    2011-01-01

    With the emergence of transparent electronics, there has been considerable advancement in n-type transparent semiconducting oxide (TSO) materials, such as ZnO, InGaZnO, and InSnO. Comparatively, the availability of p-type TSO materials is more scarce and the available materials are less mature. The development of p-type semiconductors is one of the key technologies needed to push transparent electronics and systems to the next frontier, particularly for implementing p–n junctions for solar cells and p-type transistors for complementary logic/circuits applications. Cuprous oxide (Cu 2 O) is one of the most promising candidates for p-type TSO materials. This paper reports the deposition of Cu 2 O thin films without substrate heating using a high deposition rate reactive sputtering technique, called high target utilisation sputtering (HiTUS). This technique allows independent control of the remote plasma density and the ion energy, thus providing finer control of the film properties and microstructure as well as reducing film stress. The effect of deposition parameters, including oxygen flow rate, plasma power and target power, on the properties of Cu 2 O films are reported. It is known from previously published work that the formation of pure Cu 2 O film is often difficult, due to the more ready formation or co-formation of cupric oxide (CuO). From our investigation, we established two key concurrent criteria needed for attaining Cu 2 O thin films (as opposed to CuO or mixed phase CuO/Cu 2 O films). First, the oxygen flow rate must be kept low to avoid over-oxidation of Cu 2 O to CuO and to ensure a non-oxidised/non-poisoned metallic copper target in the reactive sputtering environment. Secondly, the energy of the sputtered copper species must be kept low as higher reaction energy tends to favour the formation of CuO. The unique design of the HiTUS system enables the provision of a high density of low energy sputtered copper radicals/ions, and when combined with a

  15. Peroxisomal Polyamine Oxidase and NADPH-Oxidase cross-talk for ROS homeostasis which affects respiration rate in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Efthimios A. Andronis

    2014-04-01

    Full Text Available Homeostasis of reactive oxygen species (ROS in the intracellular compartments is of critical importance as ROS have been linked with nearly all cellular processes and more importantly with diseases and aging. PAs are nitrogenous molecules with an evolutionary conserved role in the regulation of metabolic and energetic status of cells. Recent evidence also suggests that polyamines (PA are major regulators of ROS homeostasis. In Arabidopsis the backconversion of the PAs spermidine (Spd and spermine (Spm to putrescine (Put and Spd, respectively is catalyzed by two peroxisomal PA oxidases (AtPAO. However, the physiological role of this pathway remains largely elusive. Here we explore the role of peroxisomal PA backconversion and in particular that catalyzed by the highly expressed AtPAO3 in the regulation of ROS homeostasis and mitochondrial respiratory burst. Exogenous PAs exert an NADPH-oxidase dependent stimulation of oxygen consumption, with Spd exerting the strongest effect. This increase is attenuated by treatment with the NADPH-oxidase blocker diphenyleneiodonium iodide (DPI. Loss-of-function of AtPAO3 gene results to increased NADPH-oxidase-dependent production of superoxide anions (O2.-, but not H2O2, which activate the mitochondrial alternative oxidase pathway (AOX. On the contrary, overexpression of AtPAO3 results to an increased but balanced production of both H2O2 and O2.-. These results suggest that the ratio of O2.-/H2O2 regulates respiratory chain in mitochondria, with PA-dependent production of O2.- by NADPH-oxidase tilting the balance of electron transfer chain in favor of the AOX pathway. In addition, AtPAO3 seems to be an important component in the regulating module of ROS homeostasis, while a conserved role for PA backconversion and ROS across kingdoms is discussed.

  16. Significance of membrane bioreactor design on the biocatalytic performance of glucose oxidase and catalase: Free vs. immobilized enzyme systems

    DEFF Research Database (Denmark)

    Morthensen, Sofie Thage; Meyer, Anne S.; Jørgensen, Henning

    2017-01-01

    Membrane separation of xylose and glucose can be accomplished via oxidation of glucose to gluconic acid by enzymatic glucose oxidase catalysis. Oxygen for this reaction can be supplied via decomposition of hydrogen peroxide by enzymatic catalase catalysis. In order to maximize the biocatalytic...... productivity of glucose oxidase and catalase (gluconic acid yield per total amount of enzyme) the following system set-ups were compared: immobilization of glucose oxidase alone; co-immobilization of glucose oxidase and catalase; glucose oxidase and catalase free in the membrane bioreactor. Fouling......-induced enzyme immobilization in the porous support of an ultrafiltration membrane was used as strategy for entrapment of glucose oxidase and catalase. The biocatalytic productivity of the membrane reactor was found to be highly related to the oxygen availability, which in turn depended on the reactor...

  17. The nature of the exchange coupling between high-spin Fe(III) heme o3 and CuBII in Escherichia coli quinol oxidase, cytochrome bo3: MCD and EPR studies.

    Science.gov (United States)

    Cheesman, Myles R; Oganesyan, Vasily S; Watmough, Nicholas J; Butler, Clive S; Thomson, Andrew J

    2004-04-07

    Fully oxidized cytochrome bo3 from Escherichia coli has been studied in its oxidized and several ligand-bound forms using electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectroscopies. In each form, the spin-coupled high-spin Fe(III) heme o3 and CuB(II) ion at the active site give rise to similar fast-relaxing broad features in the dual-mode X-band EPR spectra. Simulations of dual-mode spectra are presented which show that this EPR can arise only from a dinuclear site in which the metal ions are weakly coupled by an anisotropic exchange interaction of J 1 cm-1. A variable-temperature and magnetic field (VTVF) MCD study is also presented for the cytochrome bo3 fluoride and azide derivatives. New methods are used to extract the contribution to the MCD of the spin-coupled active site in the presence of strong transitions from low-spin Fe(III) heme b. Analysis of the MCD data, independent of the EPR study, also shows that the spin-coupling within the active site is weak with J approximately 1 cm-1. These conclusions overturn a long-held view that such EPR signals in bovine cytochrome c oxidase arise from an S' = 2 ground state resulting from strong exchange coupling (J > 10(2) cm-1) within the active site.

  18. Cuprous oxide thin films prepared by thermal oxidation of copper layer. Morphological and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Karapetyan, Artak, E-mail: karapetyan@cinam.univ-mrs.fr [Aix Marseille Université, CINaM, 13288, Marseille (France); Institute for Physical Research of NAS of Armenia, Ashtarak-2 0203 (Armenia); Reymers, Anna [Russian-Armenian (Slavonic) University, H.Emin st.123, Yerevan 375051 (Armenia); Giorgio, Suzanne; Fauquet, Carole [Aix Marseille Université, CINaM, 13288, Marseille (France); Sajti, Laszlo [Laser Zentrum Hannover e.V. Hollerithallee 8, 30419 Hannover (Germany); Nitsche, Serge [Aix Marseille Université, CINaM, 13288, Marseille (France); Nersesyan, Manuk; Gevorgyan, Vladimir [Russian-Armenian (Slavonic) University, H.Emin st.123, Yerevan 375051 (Armenia); Marine, Wladimir [Aix Marseille Université, CINaM, 13288, Marseille (France)

    2015-03-15

    Structural and optical characterization of crystalline Cu{sub 2}O thin films obtained by thermal oxidation of Cu films at two different temperatures 800 °C and 900 °C are investigated in this work. X-ray diffraction measurements indicate that synthesized films consist of single Cu{sub 2}O phase without any interstitial phase and show a nano-grain structure. Scanning Electron Microscopy observations indicate that the Cu{sub 2}O films have a micro-scale roughness whereas High Resolution Transmission Electron Microscopy highlights that the nanocrystalline structure is formed by superposition of nearly spherical nanocrystals smaller than 30 nm. Photoluminescence spectra of these films exhibit at room temperature two well-resolved emission peaks at 1.34 eV due to defects energy levels and at 1.97 eV due to phonon-assisted recombination of the 1s orthoexciton in both film series. Emission characteristics depending on the laser power is deeply investigated to determine the origin of recorded emissions. Time-integrated spectra of the 1s orthoexciton emission reveals the presence of oxygen defects below the conduction band edge under non-resonant two-photon excitation using a wide range of excitations wavelengths. Optical absorption coefficients at room temperature are obtained from an accurate analysis of their transmission and reflection spectra, whereas the optical band gap energy is estimated at about 2.11 eV. Results obtained are of high relevance especially for potential applications in semiconductor devices such as solar cells, optical sources and detectors. - Highlights: • Nanostructured Cu{sub 2}O thin films were synthesized by thermal oxidation of Cu films. • The PL spectra of nanostructured thin films revealed two well-resolved emission peaks. • The PL properties were investigated under a broad range of experimental conditions. • Inter-band transition in the infrared range has been associated to V{sub Cu} and V{sub O} vacancies. • Absorption

  19. The terminal oxidases of Paracoccus denitrificans

    NARCIS (Netherlands)

    de Gier, J.-W.; Lübben, M; Reijnders, W N; Tipker, C A; Slotboom, D.J.; van Spanning, R J; Stouthamer, A.H.; van der Oost, J.

    Three distinct types of terminal oxidases participate in the aerobic respiratory pathways of Paracoccus denitrificans. Two alternative genes encoding subunit I of the aa3-type cytochrome c oxidase have been isolated before, namely ctaDI and ctaDII. Each of these genes can be expressed separately to

  20. Lower Monoamine Oxidase-A Total Distribution Volume in Impulsive and Violent Male Offenders with Antisocial Personality Disorder and High Psychopathic Traits: An [(11)C] Harmine Positron Emission Tomography Study.

    Science.gov (United States)

    Kolla, Nathan J; Matthews, Brittany; Wilson, Alan A; Houle, Sylvain; Bagby, R Michael; Links, Paul; Simpson, Alexander I; Hussain, Amina; Meyer, Jeffrey H

    2015-10-01

    Antisocial personality disorder (ASPD) often presents with highly impulsive, violent behavior, and pathological changes in the orbitofrontal cortex (OFC) and ventral striatum (VS) are implicated. Several compelling reasons support a relationship between low monoamine oxidase-A (MAO-A), an enzyme that regulates neurotransmitters, and ASPD. These include MAO-A knockout models in rodents evidencing impulsive aggression and positron emission tomography (PET) studies of healthy subjects reporting associations between low brain MAO-A levels and greater impulsivity or aggression. However, a fundamental gap in the literature is that it is unknown whether brain MAO-A levels are low in more severe, clinical disorders of impulsivity, such as ASPD. To address this issue, we applied [(11)C] harmine PET to measure MAO-A total distribution volume (MAO-A VT), an index of MAO-A density, in 18 male ASPD participants and 18 age- and sex-matched controls. OFC and VS MAO-A VT were lower in ASPD compared with controls (multivariate analysis of variance (MANOVA): F2,33=6.8, P=0.003; OFC and VS MAO-A VT each lower by 19%). Similar effects were observed in other brain regions: prefrontal cortex, anterior cingulate cortex, dorsal putamen, thalamus, hippocampus, and midbrain (MANOVA: F7,28=2.7, P=0.029). In ASPD, VS MAO-A VT was consistently negatively correlated with self-report and behavioral measures of impulsivity (r=-0.50 to -0.52, all P-valuesdisorder marked by pathological aggression and impulsivity.

  1. Analysis of monoamine oxidase (MAO) enzymatic activity by high-performance liquid chromatography-diode array detection combined with an assay of oxidation with a peroxidase and its application to MAO inhibitors from foods and plants.

    Science.gov (United States)

    Herraiz, Tomás; Flores, Andrea; Fernández, Lidia

    2018-01-15

    Monoamine oxidase (MAO) enzymes catalyze the oxidative deamination of biogenic amines and neurotransmitters and produce ammonia, aldehydes, and hydrogen peroxide which is involved in oxidative processes. Inhibitors of MAO-A and -B isozymes are useful as antidepressants and neuroprotectants. The assays of MAO usually measure amine oxidation products or hydrogen peroxide by spectrophotometric techniques. Those assays are often compromised by interfering compounds resulting in poor results. This research describes a new method that combines in the same assay the oxidative deamination of kynuramine to 4-hydroxyquinoline analyzed by HPLC-DAD with the oxidation of tetramethylbenzidine (TMB) (or Amplex Rex) by horseradish peroxidase (HRP) in presence of hydrogen peroxide. The new method was applied to study the inhibition of human MAO-A and -B by bioactive compounds including β-carboline alkaloids and flavonoids occurring in foods and plants. As determined by HPLC-DAD, β-carbolines, methylene blue, kaempferol and clorgyline inhibited MAO-A and methylene blue, 5-nitroindazole, norharman and deprenyl inhibited MAO-B, and all of them inhibited the oxidation of TMB in the same extent. The flavonoids catechin and cyanidin were not inhibitors of MAO by HPLC-DAD but highly inhibited the oxidation of TMB (or Amplex Red) by peroxidase whereas quercetin and resveratrol were moderate inhibitors of MAO-A by HPLC-DAD, but inhibited the peroxidase assay in a higher level. For some phenolic compounds, using the peroxidase-coupled assay to measure MAO activity led to mistaken results. The new method permits to discern between true inhibitors of MAO from those that are antioxidants and which interfere with peroxidase assays but do not inhibit MAO. For true inhibitors of MAO, inhibition as determined by HPLC-DAD correlated well with inhibition of the oxidation of TMB and this approach can be used to assess the in vitro antioxidant activity (less hydrogen peroxide production) resulting

  2. Immobilization of oxidases and their analytical applications

    International Nuclear Information System (INIS)

    Yasinzai, M.

    2007-01-01

    Immobilized enzymes are replacing their soluble counter-parts in nearly every field of application. These enzyme modifications have evolved from a research curiosity into an entire branch of Biotechnology. An immobilization method for flavin containing oxidases and their use in flow injection system is described. An electrochemical detector for H/sub 2/O/sub 2/ is assembled which is used effectively for the determination of glucose using more common glucose oxidase and the simultaneous determination of sugars. The combination of oxidases with hydrolases have been used for the determination of maltose and starch. (author)

  3. The antioxidant properties, cytotoxicity and monoamine oxidase ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-28

    Nov 28, 2011 ... Department of Pharmaceutical Chemistry, North-West University, Private Bag X6001, Potchefstroom 2520, ..... on the inhibition of the catabolism of serotonin, .... Structure of human monoamine oxidase B, a drug target for.

  4. Vanillyl-alcohol oxidase, a tasteful biocatalyst

    NARCIS (Netherlands)

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

    2001-01-01

    The covalent flavoenzyme vanillyl-alcohol oxidase (VAO) is a versatile biocatalyst. It converts a wide range of phenolic compounds by catalysing oxidation, deamination, demethylation, dehydrogenation and hydroxylation reactions. The production of natural vanillin, 4-hydroxybenzaldehyde, coniferyl

  5. Genetics Home Reference: isolated sulfite oxidase deficiency

    Science.gov (United States)

    ... and Management Resources (1 link) GeneReview: Isolated Sulfite Oxidase Deficiency General Information from MedlinePlus (5 links) Diagnostic Tests Drug Therapy Genetic Counseling Palliative Care Surgery and ...

  6. MONOAMINE OXIDASE: RADIOTRACER DEVELOPMENT AND HUMAN STUDIES.

    Energy Technology Data Exchange (ETDEWEB)

    FOWLER,J.S.; LOGAN,J.; VOLKOW,N.D.; WANG,G.J.; MACGREGOR,R.R.; DING,Y.S.

    2000-09-28

    PET is uniquely capable of providing information on biochemical transformations in the living human body. Although most of the studies of monoamine oxidase (MAO) have focused on measurements in the brain, the role of peripheral MAO as a phase 1 enzyme for the metabolism of drugs and xenobiotics is gaining attention (Strolin Benedetti and Tipton, 1998; Castagnoli et al., 1997.). MAO is well suited for this role because its concentration in organs such as kidneys, liver and digestive organs is high sometimes exceeding that in the brain. Knowledge of the distribution of the MAO subtypes within different organs and different cells is important in determining which substrates (and which drugs and xenobiotics) have access to which MAO subtypes. The highly variable subtype distribution with different species makes human studies even more important. In addition, the deleterious side effects of combining MAO inhibitors with other drugs and with foodstuffs makes it important to know the MAO inhibitory potency of different drugs both in the brain and in peripheral organs (Ulus et al., 2000). Clearly PET can play a role in answering these questions, in drug research and development and in discovering some of the factors which contribute to the highly variable MAO levels in different individuals.

  7. Passivation Of High-Temperature Superconductors

    Science.gov (United States)

    Vasquez, Richard P.

    1991-01-01

    Surfaces of high-temperature superconductors passivated with native iodides, sulfides, or sulfates formed by chemical treatments after superconductors grown. Passivating compounds nearly insoluble in and unreactive with water and protect underlying superconductors from effects of moisture. Layers of cuprous iodide and of barium sulfate grown. Other candidate passivating surface films: iodides and sulfides of bismuth, strontium, and thallium. Other proposed techniques for formation of passivating layers include deposition and gas-phase reaction.

  8. Multi-Copper Oxidases and Human Iron Metabolism

    Science.gov (United States)

    Vashchenko, Ganna; MacGillivray, Ross T. A.

    2013-01-01

    Multi-copper oxidases (MCOs) are a small group of enzymes that oxidize their substrate with the concomitant reduction of dioxygen to two water molecules. Generally, multi-copper oxidases are promiscuous with regards to their reducing substrates and are capable of performing various functions in different species. To date, three multi-copper oxidases have been detected in humans—ceruloplasmin, hephaestin and zyklopen. Each of these enzymes has a high specificity towards iron with the resulting ferroxidase activity being associated with ferroportin, the only known iron exporter protein in humans. Ferroportin exports iron as Fe2+, but transferrin, the major iron transporter protein of blood, can bind only Fe3+ effectively. Iron oxidation in enterocytes is mediated mainly by hephaestin thus allowing dietary iron to enter the bloodstream. Zyklopen is involved in iron efflux from placental trophoblasts during iron transfer from mother to fetus. Release of iron from the liver relies on ferroportin and the ferroxidase activity of ceruloplasmin which is found in blood in a soluble form. Ceruloplasmin, hephaestin and zyklopen show distinctive expression patterns and have unique mechanisms for regulating their expression. These features of human multi-copper ferroxidases can serve as a basis for the precise control of iron efflux in different tissues. In this manuscript, we review the biochemical and biological properties of the three human MCOs and discuss their potential roles in human iron homeostasis. PMID:23807651

  9. Biocompatibility selenium nanoparticles with an intrinsic oxidase-like activity

    Science.gov (United States)

    Guo, Leilei; Huang, Kaixun; Liu, Hongmei

    2016-03-01

    Selenium nanoparticles (SeNPs) are considered to be the new selenium supplement forms with high biological activity and low toxicity; however, the molecular mechanism by which SeNPs exert the biological function is unclear. Here, we reported that biocompatibility SeNPs possessed intrinsic oxidase-like activity. Using Na2SeO3 as a precursor and glutathione as a reductant, biocompatibility SeNPs were synthesized by the wet chemical reduction method in the presence of bovine serum albumin (BSA). The results of structure characterization revealed that synthesized SeNPs were amorphous red elementary selenium with spherical morphology, and ranged in size from 25 to 70 nm size with a narrow distribution (41.4 ± 6.7 nm). The oxidase-like activity of the as-synthesized SeNPs was tested with 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. The results indicated that SeNPs could catalyze the oxidization of TMB by dissolved oxygen. These SeNPs showed an optimum catalytic activity at pH 4 and 30 °C, and the oxidase-like activity was higher as the concentration of SeNPs increased and the size of SeNPs decreased. The Michaelis constant ( K m) values and maximal reaction velocity ( V max) of the SeNPs for TMB oxidation were 0.0083 mol/L and 3.042 μmol/L min, respectively.

  10. Intracellular lysyl oxidase: Effect of a specific inhibitor on nuclear mass in proliferating cells

    Energy Technology Data Exchange (ETDEWEB)

    Saad, Fawzy A. [Laboratory for the Study of Skeletal Disorders and Rehabilitation, Department of Orthopedics, Children' s Hospital Boston, 300 Longwood Avenue EN926, Boston, MA 02115 (United States); Harvard Medical School, Boston, MA 02115 (United States); Torres, Marie [Laboratory for the Study of Skeletal Disorders and Rehabilitation, Department of Orthopedics, Children' s Hospital Boston, 300 Longwood Avenue EN926, Boston, MA 02115 (United States); Wang, Hao [Laboratory for the Study of Skeletal Disorders and Rehabilitation, Department of Orthopedics, Children' s Hospital Boston, 300 Longwood Avenue EN926, Boston, MA 02115 (United States); Harvard Medical School, Boston, MA 02115 (United States); Graham, Lila, E-mail: lilagraham@cs.com [Laboratory for the Study of Skeletal Disorders and Rehabilitation, Department of Orthopedics, Children' s Hospital Boston, 300 Longwood Avenue EN926, Boston, MA 02115 (United States); Harvard Medical School, Boston, MA 02115 (United States)

    2010-06-11

    LOX, the principal enzyme involved in crosslinking of collagen, was the first of several lysyl oxidase isotypes to be characterized. Its active form was believed to be exclusively extracellular. Active LOX was later reported to be present in cell nuclei; its function there is unknown. LOX expression opposes the effect of mutationally activated Ras, which is present in about 30% of human cancers. The mechanism of LOX in countering the action of Ras is also unknown. In the present work, assessment of nuclear protein for possible effects of lysyl oxidase activity led to the discovery that proliferating cells dramatically increase their nuclear protein content when exposed to BAPN ({beta}-aminopropionitrile), a highly specific lysyl oxidase inhibitor that reportedly blocks LOX inhibition of Ras-induced oocyte maturation. In three cell types (PC12 cells, A7r5 smooth muscle cells, and NIH 3T3 fibroblasts), BAPN caused a 1.8-, 1.7-, and 2.1-fold increase in total nuclear protein per cell, respectively, affecting all major components in both nuclear matrix and chromatin fractions. Since nuclear size is correlated with proliferative status, enzyme activity restricting nuclear growth may be involved in the lysyl oxidase tumor suppressive effect. Evidence is also presented for the presence of apparent lysyl oxidase isotype(s) containing a highly conserved LOX active site sequence in the nuclei of PC12 cells, which do not manufacture extracellular lysyl oxidase substrates. Results reported here support the hypothesis that nuclear lysyl oxidase regulates nuclear growth, and thereby modulates cell proliferation.

  11. Crystallization of carbohydrate oxidase from Microdochium nivale

    Czech Academy of Sciences Publication Activity Database

    Dušková, Jarmila; Dohnálek, Jan; Skálová, Tereza; Ostergaard, L. H.; Fuglsang, C. C.; Kolenko, Petr; Štěpánková, Andrea; Hašek, Jindřich

    2009-01-01

    Roč. 65, č. 6 (2009), s. 638-640 ISSN 1744-3091 R&D Projects: GA AV ČR IAA500500701; GA ČR GA305/07/1073 Institutional research plan: CEZ:AV0Z40500505 Keywords : carbohydrate oxidase * crystallization * data processing Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.551, year: 2009

  12. Investigation of antihemolytic, xanthine oxidase inhibition ...

    African Journals Online (AJOL)

    Abbreviations: SVEs: Salvia Verbenaca L. aerial part Extracts; CrE: Crud Extract; ChE: Chloroform Extract ; EAE: Ethyl Acetate Extract; AqE : Aqueous Extract ; ROS: Reactive Oxygen Spices; AAPH : 2,2, -Azobis (2-AmidinoPropane) Dihydrochloride ; DPPH: DiPhenyl- Picryl-Hydrazyl; XO: Xanthine Oxidase; Gen: Gentamicin ...

  13. Genetic defects of cytochrome c oxidase assembly

    Czech Academy of Sciences Publication Activity Database

    Pecina, Petr; Houšťková, H.; Hansíková, H.; Zeman, J.; Houštěk, Josef

    2004-01-01

    Roč. 53, Suppl. 1 (2004), s. S213-S223 ISSN 0862-8408 R&D Projects: GA ČR GA303/03/0749 Institutional research plan: CEZ:AV0Z5011922 Keywords : cytochrome c oxidase * mitochondrial disorders Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 1.140, year: 2004

  14. The antioxidant properties, cytotoxicity and monoamine oxidase ...

    African Journals Online (AJOL)

    Tarchonanthus camphoratus (camphor bush) has been widely used for numerous medicinal purposes. The aim of the present study was to evaluate the antioxidant properties, cytotoxicity and monoamine oxidase inhibition activities of the crude dichloromethane leaf extract of T. camphoratus. The antioxidant activities were ...

  15. Forage Polyphenol Oxidase and Ruminant Livestock Nutrition

    Directory of Open Access Journals (Sweden)

    Michael Richard F. Lee

    2014-12-01

    Full Text Available Polyphenol oxidase (PPO is associated with the detrimental effect of browning fruit and vegetables, however interest within PPO containing forage crops has grown since the brownng reaction was associated with reduced nitrogen (N losses in silo and the rumen. The reduction in protein breakdown in silo of red clover (high PPO forage increased the quality of protein, improving N-use efficiency (NUE when fed to ruminants. A further benefit of red clover silage feeding is a significant reduction in lipolysis in silo and an increase in the deposition of beneficial C18 polyunsaturated fatty acid (PUFA in animal products, which has also been linked to PPO activity. PPOs protection of plant protein and glycerol based-PUFA in silo is related to the deactivation of plant proteases and lipases. This deactivation occurs through PPO catalysing the conversion of diphenols to quinones which bind with cellular nucleophiles such as protein reforming a protein-bound phenol (PBP. If the protein is an enzyme the complexing denatures the enzyme. However, PPO is inactive in the anaerobic rumen and therefore any subsequent protection of plant protein and glycerol based-PUFA in the rumen must be as a result of events that occurred to the forage pre-ingestion. Reduced activity of plant proteases and lipases would have little effect on NUE and glycerol based-PUFA in the rumen due to the greater concentration of rumen microbial proteases and lipases. The mechanism for PPOs protection of plant protein in the rumen is a consequence of complexing plant protein, rather than protease deactivation per se. These complexed proteins reduce protein digestibility in the rumen and subsequently increase un-degraded dietary protein flow to the small intestine. The mechanism for protecting glycerol-based PUFA has yet to be fully elucidated but may be associated with entrapment within PBP reducing access to microbial lipases or differences in rumen digestion kinetics of red clover.

  16. Lysyl oxidase and adipose tissue dysfunction.

    Science.gov (United States)

    Pastel, Emilie; Price, Emily; Sjöholm, Kajsa; McCulloch, Laura J; Rittig, Nikolaj; Liversedge, Neil; Knight, Bridget; Møller, Niels; Svensson, Per-Arne; Kos, Katarina

    2018-01-01

    Lysyl oxidase (LOX) is an enzyme crucial for collagen fibre crosslinking and thus for fibrosis development. Fibrosis is characterised by a surplus of collagen fibre accumulation and is amongst others also a feature of obesity-associated dysfunctional adipose tissue (AT) which has been linked with type 2 diabetes. We hypothesised that in type 2 diabetes and obesity LOX expression and activity will be increased as a consequence of worsening AT dysfunction. This study aimed to provide a comprehensive characterisation of LOX in human AT. LOX mRNA expression was analysed in omental and abdominal subcutaneous AT obtained during elective surgery from subjects with a wide range of BMI, with and without diabetes. In addition, LOX expression was studied in subcutaneous AT before and 9.5months after bariatric surgery. To study the mechanism of LOX changes, its expression and activity were assessed after either hypoxia, recombinant human leptin or glucose treatment of AT explants. In addition, LOX response to acute inflammation was tested after stimulation by a single injection of lipopolysaccharide versus saline solution (control) in healthy men, in vivo. Quantity of mRNA was measured by RT-qPCR. LOX expression was higher in obesity and correlated with BMI whilst, in vitro, leptin at high concentrations, as a potential feedback mechanism, suppressed its expression. Neither diabetes status, nor hyperglycaemia affected LOX. Hypoxia and lipopolysaccharide-induced acute inflammation increased LOX AT expression, latter was independent of macrophage infiltration. Whilst LOX may not be affected by obesity-associated complications such as diabetes, our results confirm that LOX is increased by hypoxia and inflammation as underlying mechanism for its upregulation in adipose tissue with obesity. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. NADPH oxidases as novel pharmacologic targets against influenza A virus infection.

    Science.gov (United States)

    Vlahos, Ross; Selemidis, Stavros

    2014-12-01

    Influenza A viruses represent a major global health care challenge, with imminent pandemics, emerging antiviral resistance, and long lag times for vaccine development, raising a pressing need for novel pharmacologic strategies that ideally target the pathology irrespective of the infecting strain. Reactive oxygen species (ROS) pervade all facets of cell biology with both detrimental and protective properties. Indeed, there is compelling evidence that activation of the NADPH oxidase 2 (NOX2) isoform of the NADPH oxidase family of ROS-producing enzymes promotes lung oxidative stress, inflammation, injury, and dysfunction resulting from influenza A viruses of low to high pathogenicity, as well as impeding virus clearance. By contrast, the dual oxidase isoforms produce ROS that provide vital protective antiviral effects for the host. In this review, we propose that inhibitors of NOX2 are better alternatives than broad-spectrum antioxidant approaches for treatment of influenza pathologies, for which clinical efficacy may have been limited owing to poor bioavailability and inadvertent removal of beneficial ROS. Finally, we briefly describe the current suite of NADPH oxidase inhibitors and the molecular features of the NADPH oxidase enzymes that could be exploited by drug discovery for development of more specific and novel inhibitors to prevent or treat disease caused by influenza. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

  18. A role for NADPH oxidase in antigen presentation

    Directory of Open Access Journals (Sweden)

    Gail J Gardiner

    2013-09-01

    Full Text Available The nicotinamide adenine dinucleotide phosphate (NADPH oxidase expressed in phagocytes is a multi-subunit enzyme complex that generates superoxide (O2.-. This radical is an important precursor of hydrogen peroxide (H2O2 and other reactive oxygen species (ROS needed for microbicidal activity during innate immune responses. Inherited defects in NADPH oxidase give rise to chronic granulomatous disease (CGD, a primary immunodeficiency characterized by recurrent infections and granulomatous inflammation. Interestingly, CGD, CGD carrier status, and oxidase gene polymorphisms have all been associated with autoinflammatory and autoimmune disorders, suggesting a potential role for NADPH oxidase in regulating adaptive immune responses. Here, NADPH oxidase function in antigen processing and presentation is reviewed. NADPH oxidase influences dendritic cell (DC crosspresentation by major histocompatibility complex class I molecules (MHC-I through regulation of the phagosomal microenvironment, while in B lymphocytes, NADPH oxidase alters epitope selection by major histocompatibility complex class II molecules (MHC-II.

  19. High resolution crystal structure of rat long chain hydroxy acid oxidase in complex with the inhibitor 4-carboxy-5-[(4-chlorophenyl)sulfanyl]-1, 2, 3-thiadiazole. Implications for inhibitor specificity and drug design

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhi-wei; Vignaud, Caroline; Jaafar, Adil; Lévy, Bernard; Guéritte, Françoise; Guénard, Daniel; Lederer, Florence; Mathews, F. Scott (CNRS-UMR); (WU-MED)

    2012-05-24

    Long chain hydroxy acid oxidase (LCHAO) is responsible for the formation of methylguanidine, a toxic compound with elevated serum levels in patients with chronic renal failure. Its isozyme glycolate oxidase (GOX), has a role in the formation of oxalate, which can lead to pathological deposits of calcium oxalate, in particular in the disease primary hyperoxaluria. Inhibitors of these two enzymes may have therapeutic value. These enzymes are the only human members of the family of FMN-dependent L-2-hydroxy acid-oxidizing enzymes, with yeast flavocytochrome b{sub 2} (Fcb2) among its well studied members. We screened a chemical library for inhibitors, using in parallel rat LCHAO, human GOX and the Fcb2 flavodehydrogenase domain (FDH). Among the hits was an inhibitor, CCPST, with an IC{sub 50} in the micromolar range for all three enzymes. We report here the crystal structure of a complex between this compound and LCHAO at 1.3 {angstrom} resolution. In comparison with a lower resolution structure of this enzyme, binding of the inhibitor induces a conformational change in part of the TIM barrel loop 4, as well as protonation of the active site histidine. The CCPST interactions are compared with those it forms with human GOX and those formed by two other inhibitors with human GOX and spinach GOX. These compounds differ from CCPST in having the sulfur replaced with a nitrogen in the five-membered ring as well as different hydrophobic substituents. The possible reason for the {approx}100-fold difference in affinity between these two series of inhibitors is discussed. The present results indicate that specificity is an issue in the quest for therapeutic inhibitors of either LCHAO or GOX, but they may give leads for this quest.

  20. In vitro analysis of the role of glucose oxidase from Talaromyces flavus in biocontrol of the plant pathogen Verticillium dahliae.

    OpenAIRE

    Stosz, S K; Fravel, D R; Roberts, D P

    1996-01-01

    Culture filtrates from Talaromyces flavus grown on glucose contained high levels of glucose oxidase activity, while culture filtrates from T. flavus grown on xylan contained negligible glucose oxidase activity. Culture filtrates from T-flavus grown on both media contained complex protein profiles. However, only culture filtrates from T. flavus grown on glucose inhibited germination of microsclerotia of Verticillium dahliae in in vitro inhibition assays. A polyclonal antiserum preparation, pAB...

  1. Biocompatibility selenium nanoparticles with an intrinsic oxidase-like activity

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Leilei; Huang, Kaixun; Liu, Hongmei, E-mail: hmliu2004@126.com [Huazhong University of Science and Technology, School of Chemistry and Chemical Engineering (China)

    2016-03-15

    Selenium nanoparticles (SeNPs) are considered to be the new selenium supplement forms with high biological activity and low toxicity; however, the molecular mechanism by which SeNPs exert the biological function is unclear. Here, we reported that biocompatibility SeNPs possessed intrinsic oxidase-like activity. Using Na{sub 2}SeO{sub 3} as a precursor and glutathione as a reductant, biocompatibility SeNPs were synthesized by the wet chemical reduction method in the presence of bovine serum albumin (BSA). The results of structure characterization revealed that synthesized SeNPs were amorphous red elementary selenium with spherical morphology, and ranged in size from 25 to 70 nm size with a narrow distribution (41.4 ± 6.7 nm). The oxidase-like activity of the as-synthesized SeNPs was tested with 3,3′,5,5′-tetramethylbenzidine (TMB) as a substrate. The results indicated that SeNPs could catalyze the oxidization of TMB by dissolved oxygen. These SeNPs showed an optimum catalytic activity at pH 4 and 30 °C, and the oxidase-like activity was higher as the concentration of SeNPs increased and the size of SeNPs decreased. The Michaelis constant (K{sub m}) values and maximal reaction velocity (V{sub max}) of the SeNPs for TMB oxidation were 0.0083 mol/L and 3.042 μmol/L min, respectively.

  2. Biocompatibility selenium nanoparticles with an intrinsic oxidase-like activity

    International Nuclear Information System (INIS)

    Guo, Leilei; Huang, Kaixun; Liu, Hongmei

    2016-01-01

    Selenium nanoparticles (SeNPs) are considered to be the new selenium supplement forms with high biological activity and low toxicity; however, the molecular mechanism by which SeNPs exert the biological function is unclear. Here, we reported that biocompatibility SeNPs possessed intrinsic oxidase-like activity. Using Na 2 SeO 3 as a precursor and glutathione as a reductant, biocompatibility SeNPs were synthesized by the wet chemical reduction method in the presence of bovine serum albumin (BSA). The results of structure characterization revealed that synthesized SeNPs were amorphous red elementary selenium with spherical morphology, and ranged in size from 25 to 70 nm size with a narrow distribution (41.4 ± 6.7 nm). The oxidase-like activity of the as-synthesized SeNPs was tested with 3,3′,5,5′-tetramethylbenzidine (TMB) as a substrate. The results indicated that SeNPs could catalyze the oxidization of TMB by dissolved oxygen. These SeNPs showed an optimum catalytic activity at pH 4 and 30 °C, and the oxidase-like activity was higher as the concentration of SeNPs increased and the size of SeNPs decreased. The Michaelis constant (K m ) values and maximal reaction velocity (V max ) of the SeNPs for TMB oxidation were 0.0083 mol/L and 3.042 μmol/L min, respectively.

  3. Layer-by-Layer Assembly of Glucose Oxidase on Carbon Nanotube Modified Electrodes.

    Science.gov (United States)

    Suroviec, Alice H

    2017-01-01

    The use of enzymatically modified electrodes for the detection of glucose or other non-electrochemically active analytes is becoming increasingly common. Direct heterogeneous electron transfer to glucose oxidase has been shown to be kinetically difficult, which is why electron transfer mediators or indirect detection is usually used for monitoring glucose with electrochemical sensors. It has been found, however, that electrodes modified with single or multi-walled carbon nanotubes (CNTs) demonstrate fast heterogeneous electron transfer kinetics as compared to that found for traditional electrodes. Incorporating CNTs into the assembly of electrochemical glucose sensors, therefore, affords the possibility of facile electron transfer to glucose oxidase, and a more direct determination of glucose. This chapter describes the methods used to use CNTs in a layer-by-layer structure along with glucose oxidase to produce an enzymatically modified electrode with high turnover rates, increased stability and shelf-life.

  4. Xanthine oxidase activity and free radical generation in patients with sepsis syndrome

    DEFF Research Database (Denmark)

    Galley, H F; Davies, Michael Jonathan; Webster, N R

    1996-01-01

    OBJECTIVE: To determine xanthine oxidase activity, free radical concentrations, and lipid peroxidation in patients with sepsis syndrome compared with noninfected critically ill patients. DESIGN: A prospective observational study. SETTING: A nine-bed intensive care unit in a university teaching......). CONCLUSIONS: Patients with sepsis have xanthine oxidase activation, high free-radical concentrations, and evidence of free radical damage. The finding that xanthine oxidase activity was lower in those patients who died, coupled with increased lactate concentrations implies more severe ischemia with incomplete...... to the Acute Physiology and Chronic Health Evaluation (APACHE) II score or to the presence of organ dysfunction. The mean ascorbyl radical concentration (arbitrary units) determined by electron paramagnetic resonance following spin trapping was increased in patients compared with healthy subjects (p

  5. Role of pH in oxidase variability of Aeromonas hydrophila.

    OpenAIRE

    Hunt, L K; Overman, T L; Otero, R B

    1981-01-01

    Some strains of Aeromonas hydrophila may be oxidase negative or only weakly oxidase positive by the Kovacs method taken from the surface of a differential medium, such as MacConkey agar. Six strains of A. hydrophila, two oxidase variable, one oxidase constant, and three weakly oxidase positive on MacConkey agar, were studied to determine the cause of oxidase variability. The bacteriostatic dyes in MacConkey agar were considered possible inhibitors of the oxidase reaction. The concentration of...

  6. A broad distribution of the alternative oxidase in microsporidian parasites.

    Directory of Open Access Journals (Sweden)

    Bryony A P Williams

    2010-02-01

    Full Text Available Microsporidia are a group of obligate intracellular parasitic eukaryotes that were considered to be amitochondriate until the recent discovery of highly reduced mitochondrial organelles called mitosomes. Analysis of the complete genome of Encephalitozoon cuniculi revealed a highly reduced set of proteins in the organelle, mostly related to the assembly of iron-sulphur clusters. Oxidative phosphorylation and the Krebs cycle proteins were absent, in keeping with the notion that the microsporidia and their mitosomes are anaerobic, as is the case for other mitosome bearing eukaryotes, such as Giardia. Here we provide evidence opening the possibility that mitosomes in a number of microsporidian lineages are not completely anaerobic. Specifically, we have identified and characterized a gene encoding the alternative oxidase (AOX, a typically mitochondrial terminal oxidase in eukaryotes, in the genomes of several distantly related microsporidian species, even though this gene is absent from the complete genome of E. cuniculi. In order to confirm that these genes encode functional proteins, AOX genes from both A. locustae and T. hominis were over-expressed in E. coli and AOX activity measured spectrophotometrically using ubiquinol-1 (UQ-1 as substrate. Both A. locustae and T. hominis AOX proteins reduced UQ-1 in a cyanide and antimycin-resistant manner that was sensitive to ascofuranone, a potent inhibitor of the trypanosomal AOX. The physiological role of AOX microsporidia may be to reoxidise reducing equivalents produced by glycolysis, in a manner comparable to that observed in trypanosomes.

  7. Phospholipid alterations in cardiac sarcoplasmic reticulum induced by xanthine oxidase: contamination of commercial preparations of xanthine oxidase by phospholipase A2

    International Nuclear Information System (INIS)

    Gamache, D.A.; Kornberg, L.J.; Bartolf, M.; Franson, R.C.

    1986-01-01

    Incubation of cardiac sarcoplasmic reticulum with xanthine oxidase alone at pH 7.0 resulted in a loss of lipid phosphorus that was potentiated by the addition of xanthine. Using autoclaved E.coli with 1- 14 C-oleate in the 2-acyl position of membrane phospholipids, the authors demonstrate that many, but not all, commercial preparations of xanthine oxidase contain significant phospholipase A 2 (PLA 2 ) activity (64.3-545.6 nmols/min/mg). The PLA 2 was maximally active in the neutral-alkaline pH range, was Ca 2+ -dependent, and was unaffected by the addition of xanthine. PLA 2 activity was totally inhibited by 1mM EDTA whereas radical production by optimal concentrations of xanthine/xanthine oxidase (X/XO) was unaffected by EDTA. Chromatographically purified xanthine oxidase (Sigma Grade III) contained high levels of PLA 2 activity (64.3 nmols/min/mg) compared to endogenous levels of neutral-active, Ca 2+ -dependent PLA 2 measured in various tissue homogenates (≤ 0.5 nmols/ min/mg). Because X/XO mixtures are used extensively to study oxygen free radical-induced cell injury and membrane phospholipid alterations, the presence of a potent extracellular PLA 2 may have influenced previously published reports, and such studies should be interpreted cautiously

  8. Lysyl Oxidase and the Tumor Microenvironment

    Directory of Open Access Journals (Sweden)

    Tong-Hong Wang

    2016-12-01

    Full Text Available The lysyl oxidase (LOX family of oxidases contains a group of extracellular copper-dependent enzymes that catalyze the cross-linking of collagen and elastin by oxidation, thus maintaining the rigidity and structural stability of the extracellular matrix (ECM. Aberrant expression or activation of LOX alters the cellular microenvironment, leading to many diseases, including atherosclerosis, tissue fibrosis, and cancer. Recently, a number of studies have shown that LOX is overexpressed in most cancers and that it is involved in the regulation of tumor progression and metastasis. In contrast, a few reports have also indicated the tumor-suppressing role of LOX. In this short review, we discuss recent research on the correlations between LOX and cancer. Further, the role of LOX in tumor microenvironment remodeling, tumorigenesis, and metastasis and the underlying mechanisms have also been elucidated.

  9. Monoamine oxidase inhibitors from Gentiana lutea.

    Science.gov (United States)

    Haraguchi, Hiroyuki; Tanaka, Yasumasa; Kabbash, Amal; Fujioka, Toshihiro; Ishizu, Takashi; Yagi, Akira

    2004-08-01

    Three monoamine oxidase (MAO) inhibitors were isolated from Gentiana lutea. Their structures were elucidated to be 3-3''linked-(2'-hydroxy-4-O-isoprenylchalcone)-(2'''-hydroxy-4''-O-isoprenyldihydrochalcone) (1), 2-methoxy-3-(1,1'-dimethylallyl)-6a,10a-dihydrobenzo(1,2-c)chroman-6-one and 5-hydroxyflavanone. These compounds, and the hydrolysis product of 1, displayed competitive inhibitory properties against MAO-B which was more effective than MAO-A.

  10. Imaging Monoamine Oxidase in the Human Brain

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, J. S.; Volkow, N. D.; Wang, G-J.; Logan, Jean

    1999-11-10

    Positron emission tomography (PET) studies mapping monoamine oxidase in the human brain have been used to measure the turnover rate for MAO B; to determine the minimum effective dose of a new MAO inhibitor drug lazabemide and to document MAO inhibition by cigarette smoke. These studies illustrate the power of PET and radiotracer chemistry to measure normal biochemical processes and to provide information on the effect of drug exposure on specific molecular targets.

  11. Imaging Monoamine Oxidase in the Human Brain

    International Nuclear Information System (INIS)

    Fowler, J. S.; Volkow, N. D.; Wang, G-J.; Logan, Jean

    1999-01-01

    Positron emission tomography (PET) studies mapping monoamine oxidase in the human brain have been used to measure the turnover rate for MAO B; to determine the minimum effective dose of a new MAO inhibitor drug lazabemide and to document MAO inhibition by cigarette smoke. These studies illustrate the power of PET and radiotracer chemistry to measure normal biochemical processes and to provide information on the effect of drug exposure on specific molecular targets

  12. High performance glucose/O2 compartment-less biofuel cell using DNA/CNTs as platform for immobilizing bilirubin oxidase as novel biocathode and integrated NH2-CNTs/dendrimer/glucose dehydrogenase/nile blue as bioanode

    International Nuclear Information System (INIS)

    Korani, Aazam; Salimi, Abdollah

    2015-01-01

    Highlights: • A biocathode based on immobilization of bilirubin oxidase onto MWCNTs/DNA is designed. • The performance of MWCNTs/DNA/BOD biocathode for O 2 reduction reaction is improved. • Compared to MWCNTs/BOD,at present biocathode current density to ORR increased 3 folds. • The onset potential for ORR is 0.57 V and its current density increased to 270 μA cm −2 . • A glucose/O 2 BFC with voltage of 0.66 V, J = 172 μAcm −2 and power of 45 μW cm −2 fabricated. - Abstract: Herein, deoxyribonucleic acid (DNA)/multi-walled carbon nanotube (MWCNTs) with enhanced negative charged density was used as a novel electrochemical platform for oriented immobilization of bilirubin oxidase. The proposed support improved the direct electron transfer kinetics of BOD and its catalytic activity toward oxygen reduction reaction (ORR). In comparison to BOD enzyme which immobilized directly onto MWCNTs the current density increased three folds and reached to 270 μA cm −2 at 0.405 V with an onset potential of 0.57 V (vs. Ag/AgCl). The ability of this modified electrode as a biocathode is investigated after assembling with bioanode. The bioanode prepared with covalent attachment of glucose dehydrogenase enzyme (GDH) and nile blue (NB) as an efficient mediator for coenzyme regeneration onto glassy carbon electrode modified with amino-carbon nanotubes(MWCNTs-NH 2 ) and carboxyl terminated polyamidoamin dendrimer (PAMAM-Den) as a multifunctional linker. Finally, the performance of one-compartment glucose/O 2 biofuel cell without separators is also investigated. The open circuit voltage of the cell and maximum current density are obtained 660 mV and 172 μA cm −2 , respectively, while the maximum power density of 45 μW cm −2 is achieved at 428 mV of the cell voltage in buffer solution saturated with O 2 and containing 50 mM of glucose. The stability of the constructed EBFC is investigated under continuous operation at maximum power. It is observed that the biofuel

  13. Evaluation of the Expression of Amine Oxidase Proteins in Breast Cancer

    Directory of Open Access Journals (Sweden)

    Woo Young Sun

    2017-12-01

    Full Text Available We aimed to evaluate the expression of amine oxidase proteins in breast cancer and their clinical implications. We performed immunohistochemical staining of amine oxidase proteins (LOX, lysyl oxidase, AOC3, amine oxidase, MAOA, monoamine oxidase A, MAOB, monoamine oxidase B. Based on their hormone receptors, such as estrogen receptor (ER and progesterone receptor (PR, human epidermal growth factor receptor 2 (HER-2, and Ki-67 immunohistochemical staining, breast cancer was divided into four molecular subtypes: luminal A, luminal B, HER-2 type, and triple-negative breast cancer (TNBC. Luminal A was observed in 380 cases (49.4%, luminal B in 224 (29.1%, HER-2 type in 68 (8.8%, and TNBC in 98 (12.7%. Stromal AOC3, MAO-A, and MAO-B expression varied according to molecular subtypes. Stromal AOC3 expression was high in luminal B and HER-2 type and MAO-A expression was high in luminal A and luminal B (p < 0.001. MAO-B expression was higher in TNBC than in other subtypes (p = 0.020. LOX positivity was associated with high histological grade (p < 0.001 and high Ki-67 labeling index (LI (p = 0.009, and stromal AOC3 positivity was associated with high histological grade (p = 0.001, high Ki-67 LI (p < 0.001, and HER-2 positivity (p = 0.002. MAO-A positivity was related to low histological grade (p < 0.001, ER positivity, PR positivity (p < 0.001, and low Ki-67 LI (p < 0.001. In univariate analysis, MAO-A positivity was related to short disease-free survival in HER-2 type (p = 0.013, AOC3 negativity was related to short disease-free survival and overall survival in ER-positive breast cancer, PR-positive breast cancer, HER-2-negative breast cancer, and lymph node metastasis. In conclusion, the expression of amine oxidase proteins varies depending on the molecular subtype of breast cancer. Stromal AOC3 expression was high in luminal B and HER-2 type, and MAO-A expression was high in luminal A and luminal B.

  14. Expanding the substrate scope of chitooligosaccharide oxidase from Fusarium graminearum by structure-inspired mutagenesis

    NARCIS (Netherlands)

    Ferrari, Alessandro; Lee, Misun; Fraaije, Marco

    2015-01-01

    Chitooligosaccharide oxidase from Fusarium graminearum (ChitO) oxidizes N-acetyl-D-glucosamine (GlcNAc) and its oligomers with high efficiency at the C1-hydroxyl moiety while it shows poor or no activity with other carbohydrates. By sequence and structural comparison with other known carbohydrate

  15. Are colorimetric assays appropriate for measuring phenol oxidase activity in peat soils?

    Science.gov (United States)

    Magdalena M. Wiedermann; Evan S. Kane; Timothy J. Veverica; Erik A. Lilleskov

    2017-01-01

    The activity of extracellular phenol oxidases is believed to play a critical role in decomposition processes in peatlands. The water logged, acidic conditions, and recalcitrant litter from the peatland vegetation, lead to exceptionally high phenolics in the peat. In order to quantify the activity of oxidative enzymes involved in the modification and break down of...

  16. Functional Assembly of Soluble and Membrane Recombinant Proteins of Mammalian NADPH Oxidase Complex.

    Science.gov (United States)

    Souabni, Hajer; Ezzine, Aymen; Bizouarn, Tania; Baciou, Laura

    2017-01-01

    Activation of phagocyte cells from an innate immune system is associated with a massive consumption of molecular oxygen to generate highly reactive oxygen species (ROS) as microbial weapons. This is achieved by a multiprotein complex, the so-called NADPH oxidase. The activity of phagocyte NADPH oxidase relies on an assembly of more than five proteins, among them the membrane heterodimer named flavocytochrome b 558 (Cytb 558 ), constituted by the tight association of the gp91 phox (also named Nox2) and p22 phox proteins. The Cytb 558 is the membrane catalytic core of the NADPH oxidase complex, through which the reducing equivalent provided by NADPH is transferred via the associated prosthetic groups (one flavin and two hemes) to reduce dioxygen into superoxide anion. The other major proteins (p47 phox , p67 phox , p40 phox , Rac) requisite for the complex activity are cytosolic proteins. Thus, the NADPH oxidase functioning relies on a synergic multi-partner assembly that in vivo can be hardly studied at the molecular level due to the cell complexity. Thus, a cell-free assay method has been developed to study the NADPH oxidase activity that allows measuring and eventually quantifying the ROS generation based on optical techniques following reduction of cytochrome c. This setup is a valuable tool for the identification of protein interactions, of crucial components and additives for a functional enzyme. Recently, this method was improved by the engineering and the production of a complete recombinant NADPH oxidase complex using the combination of purified proteins expressed in bacterial and yeast host cells. The reconstitution into artificial membrane leads to a fully controllable system that permits fine functional studies.

  17. Modulation of NADPH oxidase activity by known uraemic retention solutes

    DEFF Research Database (Denmark)

    Schulz, Anna Marta; Terne, Cindy; Jankowski, Vera

    2014-01-01

    chloride (DPI), an inhibitor of NADPH oxidase. The effect on enzymatic activity of NADPH oxidase was quantified within an incubation time of 120 min. RESULTS: Thirty-nine of the 48 uraemic retention solutes tested had a significant decreasing effect on NADPH oxidase activity. Oxalate has been characterized......BACKGROUND: Uraemia and cardiovascular disease appear to be associated with an increased oxidative burden. One of the key players in the genesis of reactive oxygen species (ROS) is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Based on initial experiments demonstrating a decreased...... inhibitory effect on NADPH oxidase activity in the presence of plasma from patients with CKD-5D after dialysis compared with before dialysis, we investigated the effect of 48 known and commercially available uraemic retention solutes on the enzymatic activity of NADPH oxidase. METHODS: Mononuclear leucocytes...

  18. Fabrication of high performance bioanode based on fruitful association of dendrimer and carbon nanotube used for design O2/glucose membrane-less biofuel cell with improved bilirubine oxidase biocathode.

    Science.gov (United States)

    Korani, Aazam; Salimi, Abdollah

    2013-12-15

    In this study, the preparation of an integrated modified electrode based on the covalent attachment of glucose dehydrogenase (GDH) enzyme and safranin O to amine-derivative multiwalled carbon nanotubes (MWCNTs-NH2) modified glassy carbon (GC) electrode using G2.5-carboxylated PAMAM dendrimer (Den) as linking agent is reported. The obtained results indicated that the proposed system has effective bioelectrocatalytic activity toward glucose oxidation at 100 mV with onset potential of -130 mV (vs. Ag/AgCl). The performance of the prepared hybrid system of GC/MWCNTs-NH2/Den/GDH/Safranin as anode in a membraneless enzyme-based glucose/O2 biofuel cell is further evaluated. The biocathode in this system was composed of bilirubin oxidase (BOX) enzyme immobilized onto a bilirubin modified carbon nanotube GC electrode. Immobilized BOX onto CNTs/bilirubin not only show direct electron transfer but also it has excellent electrocatalytic activity toward oxygen reduction at a positive potential of 610 mV. The open circuit voltage of the cell was 590 mV. The maximum current density was 0.5 mA cm(-2), while maximum power density of 108 μW cm(-2) was achieved at voltage of 330 mV. The immobilized enzymes in anode and cathode are very stable and output power of the BFC is approximately constant after 12 h continues operation. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Chemoenzymatic combination of glucose oxidase with titanium silicalite -1

    DEFF Research Database (Denmark)

    Vennestrøm, Peter Nicolai Ravnborg; Taarning, Esben; Christensen, Claus H.

    2010-01-01

    Zeozymes: A proof-of-concept is presented for the chemoenzymatic combination of titanium silicalite-1 zeolite with glucose oxidase. In this combination, glucose is oxidized to gluconic acid and the H2O2 byproduct formed in situ is used for the simultaneous oxidation of chemical substrates. Both...... a soluble glucose oxidase and a truly integrated heterogeneous combination whereby the oxidase enzyme is anchored onto the zeolite surface are reported....

  20. Plasma diamine oxidase levels in pregnancy complicated by threatened abortion.

    Science.gov (United States)

    Legge, M; Duff, G B

    1981-02-01

    Plasma diamine oxidase levels were assayed in 66 patients who presented with pregnancy complicated by threatened abortion. Levels within the normal range were associated with continuing pregnancies, whereas levels below the normal range were associated with subsequent abortion. Among those patients in whom gestation was greater than eight weeks, 66.6% of diamine oxidase levels correctly predicted the pregnancy outcome. Assay of the diamine oxidase levels at eight weeks of gestation or less gave little useful information.

  1. Plasma diamine oxidase levels in pregnancy complicated by threatened abortion.

    OpenAIRE

    Legge, M; Duff, G B

    1981-01-01

    Plasma diamine oxidase levels were assayed in 66 patients who presented with pregnancy complicated by threatened abortion. Levels within the normal range were associated with continuing pregnancies, whereas levels below the normal range were associated with subsequent abortion. Among those patients in whom gestation was greater than eight weeks, 66.6% of diamine oxidase levels correctly predicted the pregnancy outcome. Assay of the diamine oxidase levels at eight weeks of gestation or less ga...

  2. Gravity Responsive NADH Oxidase of the Plasma Membrane

    Science.gov (United States)

    Morre, D. James (Inventor)

    2002-01-01

    A method and apparatus for sensing gravity using an NADH oxidase of the plasma membrane which has been found to respond to unit gravity and low centrifugal g forces. The oxidation rate of NADH supplied to the NADH oxidase is measured and translated to represent the relative gravitational force exerted on the protein. The NADH oxidase of the plasma membrane may be obtained from plant or animal sources or may be produced recombinantly.

  3. Reengineered glucose oxidase for amperometric glucose determination in diabetes analytics.

    Science.gov (United States)

    Arango Gutierrez, Erik; Mundhada, Hemanshu; Meier, Thomas; Duefel, Hartmut; Bocola, Marco; Schwaneberg, Ulrich

    2013-12-15

    Glucose oxidase is an oxidoreductase exhibiting a high β-D-glucose specificity and high stability which renders glucose oxidase well-suited for applications in diabetes care. Nevertheless, GOx activity is highly oxygen dependent which can lead to inaccuracies in amperometric β-D-glucose determinations. Therefore a directed evolution campaign with two rounds of random mutagenesis (SeSaM followed by epPCR), site saturation mutagenesis studies on individual positions, and one simultaneous site saturation library (OmniChange; 4 positions) was performed. A diabetes care well suited mediator (quinone diimine) was selected and the GOx variant (T30V I94V) served as starting point. For directed GOx evolution a microtiter plate detection system based on the quinone diimine mediator was developed and the well-known ABTS-assay was applied in microtiter plate format to validate oxygen independency of improved GOx variants. Two iterative rounds of random diversity generation and screening yielded to two subsets of amino acid positions which mainly improved activity (A173, A332) and oxygen independency (F414, V560). Simultaneous site saturation of all four positions with a reduced subset of amino acids using the OmniChange method yielded finally variant V7 with a 37-fold decreased oxygen dependency (mediator activity: 7.4 U/mg WT, 47.5 U/mg V7; oxygen activity: 172.3 U/mg WT, 30.1 U/mg V7). V7 is still highly β-D-glucose specific, highly active with the quinone diimine mediator and thermal resistance is retained (prerequisite for GOx coating of diabetes test stripes). The latter properties and V7's oxygen insensitivity make V7 a very promising candidate to replace standard GOx in diabetes care applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Suicide attempts, platelet monoamine oxidase and the average evoked response

    International Nuclear Information System (INIS)

    Buchsbaum, M.S.; Haier, R.J.; Murphy, D.L.

    1977-01-01

    The relationship between suicides and suicide attempts and two biological measures, platelet monoamine oxidase levels (MAO) and average evoked response (AER) augmenting was examined in 79 off-medication psychiatric patients and in 68 college student volunteers chosen from the upper and lower deciles of MAO activity levels. In the patient sample, male individuals with low MAO and AER augmenting, a pattern previously associated with bipolar affective disorders, showed a significantly increased incidence of suicide attempts in comparison with either non-augmenting low MAO or high MAO patients. Within the normal volunteer group, all male low MAO probands with a family history of suicide or suicide attempts were AER augmenters themselves. Four completed suicides were found among relatives of low MAO probands whereas no high MAO proband had a relative who committed suicide. These findings suggest that the combination of low platelet MAO activity and AER augmenting may be associated with a possible genetic vulnerability to psychiatric disorders. (author)

  5. Cuprous Oxide as a Potential Low-Cost Hole-Transport Material for Stable Perovskite Solar Cells.

    Science.gov (United States)

    Nejand, Bahram Abdollahi; Ahmadi, Vahid; Gharibzadeh, Saba; Shahverdi, Hamid Reza

    2016-02-08

    Inorganic hole-transport materials are commercially desired to decrease the fabrication cost of perovskite solar cells. Here, Cu2O is introduced as a potential hole-transport material for stable, low-cost devices. Considering that Cu2O formation is highly sensitive to the underlying mixture of perovskite precursors and their solvents, we proposed and engineered a technique for reactive magnetron sputtering. The rotational angular deposition of Cu2O yields high surface coverage of the perovskite layer for high rate of charge extraction. Deposition of this Cu2O layer on the pinhole-free perovskite layer produces devices with power conversion efficiency values of up to 8.93%. The engineered Cu2O layers showed uniform, compact, and crack-free surfaces on the perovskite layer without affecting the perovskite structure, which is desired for deposition of the top metal contact and for surface shielding against moisture and mechanical damages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Salicylic Acid Regulation of Respiration in Higher Plants: Alternative Oxidase Expression.

    Science.gov (United States)

    Rhoads, DM; McIntosh, L

    1992-01-01

    Alternative respiratory pathway capacity increases during the development of the thermogenic appendix of a voodoo lily inflorescence. The levels of the alternative oxidase proteins increased dramatically between D-4 (4 days prior to the day of anthesis) and D-3 and continued to increase until the day of anthesis (D-day). The level of salicylic acid (SA) in the appendix is very low early on D-1, but increases to a high level in the evening of D-1. Thermogenesis occurs after a few hours of light on D-day. Therefore, the initial accumulation of the alternative oxidase proteins precedes the increase in SA by 3 days, indicating that other regulators may be involved. A 1.6-kb transcript encoding the alternative oxidase precursor protein accumulated to a high level in the appendix tissue by D-1. Application of SA to immature appendix tissue caused an increase in alternative pathway capacity and a dramatic accumulation of the alternative oxidase proteins and the 1.6-kb transcript. Time course experiments showed that the increase in capacity, protein levels, and transcript level corresponded precisely. The response to SA was blocked by cycloheximide or actinomycin D, indicating that de novo transcription and translation are required. However, nuclear, in vitro transcription assays indicated that the accumulation of the 1.6-kb transcript did not result from a simple increase in the rate of transcription of aox1. PMID:12297672

  7. Biocatalytic potential of laccase-like multicopper oxidases from Aspergillus niger

    Directory of Open Access Journals (Sweden)

    Tamayo-Ramos Juan Antonio

    2012-12-01

    Full Text Available Abstract Background Laccase-like multicopper oxidases have been reported in several Aspergillus species but they remain uncharacterized. The biocatalytic potential of the Aspergillus niger fungal pigment multicopper oxidases McoA and McoB and ascomycete laccase McoG was investigated. Results The laccase-like multicopper oxidases McoA, McoB and McoG from the commonly used cell factory Aspergillus niger were homologously expressed, purified and analyzed for their biocatalytic potential. All three recombinant enzymes were monomers with apparent molecular masses ranging from 80 to 110 kDa. McoA and McoG resulted to be blue, whereas McoB was yellow. The newly obtained oxidases displayed strongly different activities towards aromatic compounds and synthetic dyes. McoB exhibited high catalytic efficiency with N,N-dimethyl-p-phenylenediamine (DMPPDA and 2,2-azino-di(3-ethylbenzthiazoline sulfonic acid (ABTS, and appeared to be a promising biocatalyst. Besides oxidizing a variety of phenolic compounds, McoB catalyzed successfully the decolorization and detoxification of the widely used textile dye malachite green. Conclusions The A. niger McoA, McoB, and McoG enzymes showed clearly different catalytic properties. Yellow McoB showed broad substrate specificity, catalyzing the oxidation of several phenolic compounds commonly present in different industrial effluents. It also harbored high decolorization and detoxification activity with the synthetic dye malachite green, showing to have an interesting potential as a new industrial biocatalyst.

  8. Association of ventral striatum monoamine oxidase-A binding and functional connectivity in antisocial personality disorder with high impulsivity: A positron emission tomography and functional magnetic resonance imaging study.

    Science.gov (United States)

    Kolla, Nathan J; Dunlop, Katharine; Downar, Jonathan; Links, Paul; Bagby, R Michael; Wilson, Alan A; Houle, Sylvain; Rasquinha, Fawn; Simpson, Alexander I; Meyer, Jeffrey H

    2016-04-01

    Impulsivity is a core feature of antisocial personality disorder (ASPD) associated with abnormal brain function and neurochemical alterations. The ventral striatum (VS) is a key region of the neural circuitry mediating impulsive behavior, and low monoamine oxidase-A (MAO-A) level in the VS has shown a specific relationship to the impulsivity of ASPD. Because it is currently unknown whether phenotypic MAO-A markers can influence brain function in ASPD, we investigated VS MAO-A level and the functional connectivity (FC) of two seed regions, superior and inferior VS (VSs, VSi). Nineteen impulsive ASPD males underwent [(11)C] harmine positron emission tomography scanning to measure VS MAO-A VT, an index of MAO-A density, and resting-state functional magnetic resonance imaging that assessed the FC of bilateral seed regions in the VSi and VSs. Subjects also completed self-report impulsivity measures. Results revealed functional coupling of the VSs with bilateral dorsomedial prefrontal cortex (DMPFC) that was correlated with VS MAO-A VT (r=0.47, p=0.04), and functional coupling of the VSi with right hippocampus that was anti-correlated with VS MAO-A VT (r=-0.55, p=0.01). Additionally, VSs-DMPFC FC was negatively correlated with NEO Personality Inventory-Revised impulsivity (r=-0.49, p=0.03), as was VSi-hippocampus FC with Barratt Impulsiveness Scale-11 motor impulsiveness (r=-0.50, p=0.03). These preliminary results highlight an association of VS MAO-A level with the FC of striatal regions linked to impulsive behavior in ASPD and suggest that phenotype-based brain markers of ASPD have relevance to understanding brain function. Copyright © 2016 Elsevier B.V. and ECNP. All rights reserved.

  9. Perspective: Maintaining surface-phase purity is key to efficient open air fabricated cuprous oxide solar cells

    International Nuclear Information System (INIS)

    Hoye, Robert L. Z.; Ievskaya, Yulia; MacManus-Driscoll, Judith L.; Brandt, Riley E.; Buonassisi, Tonio; Heffernan, Shane; Musselman, Kevin P.

    2015-01-01

    Electrochemically deposited Cu 2 O solar cells are receiving growing attention owing to a recent doubling in efficiency. This was enabled by the controlled chemical environment used in depositing doped ZnO layers by atomic layer deposition, which is not well suited to large-scale industrial production. While open air fabrication with atmospheric pressure spatial atomic layer deposition overcomes this limitation, we find that this approach is limited by an inability to remove the detrimental CuO layer that forms on the Cu 2 O surface. Herein, we propose strategies for achieving efficiencies in atmospherically processed cells that are equivalent to the high values achieved in vacuum processed cells

  10. NADPH oxidase: an enzyme for multicellularity?

    Science.gov (United States)

    Lalucque, Hervé; Silar, Philippe

    2003-01-01

    Multicellularity has evolved several times during the evolution of eukaryotes. One evolutionary pressure that permits multicellularity relates to the division of work, where one group of cells functions as nutrient providers and the other in specialized roles such as defence or reproduction. This requires signalling systems to ensure harmonious development of multicellular structures. Here, we show that NADPH oxidases are specifically present in organisms that differentiate multicellular structures during their life cycle and are absent from unicellular life forms. The biochemical properties of these enzymes make them ideal candidates for a role in intercellular signalling.

  11. Octahedral core–shell cuprous oxide/carbon with enhanced electrochemical activity and stability as anode for lithium ion batteries

    International Nuclear Information System (INIS)

    Xiang, Jiayuan; Chen, Zhewei; Wang, Jianming

    2015-01-01

    Highlights: • Core–shell octahedral Cu 2 O/C is prepared by a one-step method. • Carbon shell is amorphous and uniformly decorated at the Cu 2 O octahedral core. • Core–shell Cu 2 O/C exhibits markedly enhanced capability and reversibility. • Carbon shell provides fast ion/electron transfer channel. • Core–shell structure is stable during cycling. - Abstract: Core–shell Cu 2 O/C octahedrons are synthesized by a simple hydrothermal method with the help of carbonization of glucose, which reduces Cu(II) to Cu(I) at low temperature and further forms carbon shell coating at high temperature. SEM and TEM images indicate that the carbon shell is amorphous with thickness of ∼20 nm wrapping the Cu 2 O octahedral core perfectly. As anode of lithium ion batteries, the core–shell Cu 2 O/C composite exhibits high and stable columbic efficiency (98%) as well as a reversible capacity of 400 mAh g −1 after 80 cycles. The improved electrochemical performance is attributed to the novel core–shell structure, in which the carbon shell reduces the electrode polarization and promotes the charge transfer at active material/electrolyte interface, and also acts as a stabilizer to keep the octahedral structure integrity during discharge–charge processes

  12. Perspective: Maintaining surface-phase purity is key to efficient open air fabricated cuprous oxide solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hoye, Robert L. Z., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk; Ievskaya, Yulia; MacManus-Driscoll, Judith L., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Brandt, Riley E.; Buonassisi, Tonio [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Heffernan, Shane [Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Musselman, Kevin P. [Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2015-02-01

    Electrochemically deposited Cu{sub 2}O solar cells are receiving growing attention owing to a recent doubling in efficiency. This was enabled by the controlled chemical environment used in depositing doped ZnO layers by atomic layer deposition, which is not well suited to large-scale industrial production. While open air fabrication with atmospheric pressure spatial atomic layer deposition overcomes this limitation, we find that this approach is limited by an inability to remove the detrimental CuO layer that forms on the Cu{sub 2}O surface. Herein, we propose strategies for achieving efficiencies in atmospherically processed cells that are equivalent to the high values achieved in vacuum processed cells.

  13. Analysis of an HVAC system for the molten cuprous chloride pouring operation in an industrial hydrogen production facility

    Energy Technology Data Exchange (ETDEWEB)

    Ghandehariun, S.; Talimi, M.; Rosen, M.A.; Naterer, G.F. [University of Ontario Inst. of Technology, Oshawa, ON (Canada). Faculty of Engineering and Applied Science

    2010-07-01

    Hydrogen can be produced by thermochemical water decomposition from various heat sources. The copper-chlorine (Cu-Cl) cycle is a potential future cycle that could be linked with nuclear reactors to thermally decompose water into oxygen and hydrogen, through intermediate copper and chlorine compounds. Heat is transferred between various processes. Effective heat recovery from the molten CuCl within the cycle is important for achieving high efficiency. This paper described the fundamentals of a preliminary HVAC system design for the molten CuCl pouring operation in an industrial facility, and the use of air cleaning devices to remove contaminants before discharge to the outdoor air. Heat recovery from molten CuCl involves calculating duct diameters to provide the desired duct air velocity through the system. The fan size is determined by evaluating the static pressure. An adequate supply of make-up air must be provided to replace the air exhausted through the ventilation system. This paper described the economics of the ventilation system as well as ways to protect employee health and minimize the costs associated with exhaust ventilation. 20 refs., 1 tab., 5 figs.

  14. The microglial NADPH oxidase complex as a source of oxidative stress in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Landreth Gary E

    2006-11-01

    Full Text Available Abstract Alzheimer's disease is the most common cause of dementia in the elderly, and manifests as progressive cognitive decline and profound neuronal loss. The principal neuropathological hallmarks of Alzheimer's disease are the senile plaques and the neurofibrillary tangles. The senile plaques are surrounded by activated microglia, which are largely responsible for the proinflammatory environment within the diseased brain. Microglia are the resident innate immune cells in the brain. In response to contact with fibrillar beta-amyloid, microglia secrete a diverse array of proinflammatory molecules. Evidence suggests that oxidative stress emanating from activated microglia contribute to the neuronal loss characteristic of this disease. The source of fibrillar beta-amyloid induced reactive oxygen species is primarily the microglial nicotinamide adenine dinucleotide phosphate (NADPH oxidase. The NADPH oxidase is a multicomponent enzyme complex that, upon activation, produces the highly reactive free radical superoxide. The cascade of intracellular signaling events leading to NADPH oxidase assembly and the subsequent release of superoxide in fibrillar beta-amyloid stimulated microglia has recently been elucidated. The induction of reactive oxygen species, as well as nitric oxide, from activated microglia can enhance the production of more potent free radicals such as peroxynitrite. The formation of peroxynitrite causes protein oxidation, lipid peroxidation and DNA damage, which ultimately lead to neuronal cell death. The elimination of beta-amyloid-induced oxidative damage through the inhibition of the NADPH oxidase represents an attractive therapeutic target for the treatment of Alzheimer's disease.

  15. Crystallization of carbohydrate oxidase from Microdochium nivale

    International Nuclear Information System (INIS)

    Dušková, Jarmila; Dohnálek, Jan; Skálová, Tereza; Østergaard, Lars Henrik; Fuglsang, Claus Crone; Kolenko, Petr; Štěpánková, Andrea; Hašek, Jindřich

    2009-01-01

    Industrially used carbohydrate oxidase was successfully crystallized in several forms, diffraction data suitable for structural analysis were collected. Microdochium nivale carbohydrate oxidase was produced by heterologous recombinant expression in Aspergillus oryzae, purified and crystallized. The enzyme crystallizes with varying crystal morphologies depending on the crystallization conditions. Several different crystal forms were obtained using the hanging-drop vapour-diffusion method, two of which were used for diffraction measurements. Hexagon-shaped crystals (form I) diffracted to 2.66 Å resolution, with unit-cell parameters a = b = 55.7, c = 610.4 Å and apparent space group P6 2 22. Analysis of the data quality showed almost perfect twinning of the crystals. Attempts to solve the structure by molecular replacement did not give satisfactory results. Recently, clusters of rod-shaped crystals (form II) were grown in a solution containing PEG MME 550. These crystals belonged to the monoclinic system C2, with unit-cell parameters a = 132.9, b = 56.6, c = 86.5 Å, β = 95.7°. Data sets were collected to a resolution of 2.4 Å. The structure was solved by the molecular-replacement method. Model refinement is currently in progress

  16. Purification and characterization of amine oxidase from soybean seedlings.

    Science.gov (United States)

    Vianello, F; Di Paolo, M L; Stevanato, R; Gasparini, R; Rigo, A

    1993-11-15

    A simple and rapid procedure for purification of soybean seedling amine oxidase is reported. The crude enzyme, obtained by ammonium sulfate fractionation was purified by ion-exchange chromatography on a cellulose phosphate column and batch affinity chromatography on 6-aminohexyl-Sepharose. Cyclohexylamine, a competitive inhibitor, was utilized to elute the enzyme. A homogeneous enzyme was obtained with a yield higher than 25%, the content of minor components being lauryl sulfate-polyacrylamide gel electrophoresis. The enzyme is a dimer and contains two Cu2+ ion per molecule. Its EPR spectrum is typical of Cu2+ in a tetragonal symmetry. The enzyme oxidizes cadaverine at high rate, the specific activity being 4.3 mukat/mg. Molecular, spectroscopic, and kinetic properties of this enzyme are reported.

  17. Cytochemical Localization of Glucose Oxidase in Peroxisomes of Aspergillus niger

    NARCIS (Netherlands)

    Veenhuis, Marten; Dijken, Johannes Pieter van

    1980-01-01

    The subcellular localization of glucose oxidase (E.C. 1.1.3.4) in mycelia of Aspergillus niger has been investigated using cytochemical staining techniques. Mycelia from fermenter cultures, which produced gluconic acid from glucose, contained elevated levels of glucose oxidase and catalase. Both

  18. Xanthine oxidase in human skeletal muscle following eccentric exercise

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Frandsen, Ulrik; Orthenblad, N.

    1997-01-01

    the increase in xanthine oxidase in the muscle there were no detectable changes in the levels of muscle malondialdehyde or in plasma antioxidant capacity up to 4 days post-exercise. 5. It is concluded that eccentric exercise leads to an increased level of xanthine oxidase in human muscle and that the increase...

  19. Laboratory-evolved vanillyl-alcohol oxidase produces natural vanillin

    NARCIS (Netherlands)

    Heuvel, van den R.H.H.; Berg, van den W.A.M.; Rovida, S.; Berkel, van W.J.H.

    2004-01-01

    The flavoenzyme vanillyl-alcohol oxidase was subjected to random mutagenesis to generate mutants with enhanced reactivity to creosol (2-methoxy-4-methylphenol). The vanillyl-alcohol oxidase-mediated conversion of creosol proceeds via a two-step process in which the initially formed vanillyl alcohol

  20. Optimization of glucose oxidase production by Aspergillus niger

    African Journals Online (AJOL)

    user

    2011-02-28

    Feb 28, 2011 ... manganese, cobalt, thioglycolic acid, and gluconic acid according to (Liu et al., .... In this experiment duplicate media of glucose 10% were adjusted at different ... Glucose oxidase as a pharmaceutical anti oxidant Drug. Devt. ... Plush KS, Hellmuth K, Rinas U (1996). kinetics of glucose oxidase excretion by ...

  1. 21 CFR 866.2420 - Oxidase screening test for gonorrhea.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxidase screening test for gonorrhea. 866.2420... screening test for gonorrhea. (a) Identification. An oxidase screening test for gonorrhea is an in vitro... of gonorrhea. (b) Classification. Class III (premarket approval) (transitional device). (c) Date PMA...

  2. Modulation of NADPH oxidase activity by known uraemic retention solutes.

    Science.gov (United States)

    Schulz, Anna Marta; Terne, Cindy; Jankowski, Vera; Cohen, Gerald; Schaefer, Mandy; Boehringer, Falko; Tepel, Martin; Kunkel, Desiree; Zidek, Walter; Jankowski, Joachim

    2014-08-01

    Uraemia and cardiovascular disease appear to be associated with an increased oxidative burden. One of the key players in the genesis of reactive oxygen species (ROS) is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Based on initial experiments demonstrating a decreased inhibitory effect on NADPH oxidase activity in the presence of plasma from patients with CKD-5D after dialysis compared with before dialysis, we investigated the effect of 48 known and commercially available uraemic retention solutes on the enzymatic activity of NADPH oxidase. Mononuclear leucocytes isolated from buffy coats of healthy volunteers were isolated, lysed and incubated with NADH in the presence of plasma from healthy controls and patients with CKD-5D. Furthermore, the leucocytes were lysed and incubated in the presence of uraemic retention solute of interest and diphenyleneiodonium chloride (DPI), an inhibitor of NADPH oxidase. The effect on enzymatic activity of NADPH oxidase was quantified within an incubation time of 120 min. Thirty-nine of the 48 uraemic retention solutes tested had a significant decreasing effect on NADPH oxidase activity. Oxalate has been characterized as the strongest inhibitor of NADPH oxidase (90% of DPI inhibition). Surprisingly, none of the uraemic retention solutes we investigated was found to increase NADPH oxidase activity. Furthermore, plasma from patients with CKD-5D before dialysis caused significantly higher inhibitory effect on NADPH oxidase activity compared with plasma from healthy subjects. However, this effect was significantly decreased in plasma from patients with CKD-5D after dialysis. The results of this study show that uraemic retention solutes modulated the activity of the NADPH oxidase. The results of this study might be the basis for the development of inhibitors applicable as drug in the situation of increased oxidative stress. © 2014 Stichting European Society for Clinical Investigation Journal Foundation.

  3. X-ray analysis of bilirubin oxidase from Myrothecium verrucaria at 2.3 Å resolution using a twinned crystal

    International Nuclear Information System (INIS)

    Mizutani, Kimihiko; Toyoda, Mayuko; Sagara, Kenta; Takahashi, Nobuyuki; Sato, Atsuko; Kamitaka, Yuji; Tsujimura, Seiya; Nakanishi, Yuji; Sugiura, Toshiyuki; Yamaguchi, Shotaro; Kano, Kenji; Mikami, Bunzo

    2010-01-01

    The crystal structure of bilirubin oxidase (BOD) from M. verrucaria has been determined at 2.3 Å resolution using a merohedrally twinned crystal. BOD has four copper-coordination sites that are almost identical to those of other multicopper oxidases and is also very similar to them in overall structure. Bilirubin oxidase (BOD), a multicopper oxidase found in Myrothecium verrucaria, catalyzes the oxidation of bilirubin to biliverdin. Oxygen is the electron acceptor and is reduced to water. BOD is used for diagnostic analysis of bilirubin in serum and has attracted considerable attention as an enzymatic catalyst for the cathode of biofuel cells that work under neutral conditions. Here, the crystal structure of BOD is reported for the first time. Blue bipyramid-shaped crystals of BOD obtained in 2-methyl-2,4-pentanediol (MPD) and ammonium sulfate solution were merohedrally twinned in space group P6 3 . Structure determination was achieved by the single anomalous diffraction (SAD) method using the anomalous diffraction of Cu atoms and synchrotron radiation and twin refinement was performed in the resolution range 33–2.3 Å. The overall organization of BOD is almost the same as that of other multicopper oxidases: the protein is folded into three domains and a total of four copper-binding sites are found in domains 1 and 3. Although the four copper-binding sites were almost identical to those of other multicopper oxidases, the hydrophilic Asn residue (at the same position as a hydrophobic residue such as Leu in other multicopper oxidases) very close to the type I copper might contribute to the characteristically high redox potential of BOD

  4. Dynamic 1-aminocyclopropane-1-carboxylate-synthase and -oxidase transcript accumulation patterns during pollen tube growth in tobacco styles.

    Science.gov (United States)

    Weterings, Koen; Pezzotti, Mario; Cornelissen, Marc; Mariani, Celestina

    2002-11-01

    In flowering plants, pollination of the stigma sets off a cascade of responses in the distal flower organs. Ethylene and its biosynthetic precursor 1-aminocyclopropane-1-carboxylate (ACC) play an important role in regulating these responses. Because exogenous application of ethylene or ACC does not invoke the full postpollination syndrome, the pollination signal probably consists of a more complex set of stimuli. We set out to study how and when the pollination signal moves through the style of tobacco (Nicotiana tabacum) by analyzing the expression patterns of pistil-expressed ACC-synthase and -oxidase genes. Results from this analysis showed that pollination induces high ACC-oxidase transcript levels in all cells of the transmitting tissue. ACC-synthase mRNA accumulated only in a subset of transmitting tract cells and to lower levels as compared with ACC-oxidase. More significantly, we found that although ACC-oxidase transcripts accumulate to uniform high levels, the ACC-synthase transcripts accumulate in a wave-like pattern in which the peak coincides with the front of the ingrowing pollen tube tips. This wave of ACC-synthase expression can also be induced by incongruous pollination and (partially) by wounding. This indicates that wounding-like features of pollen tube invasion might be part of the stimuli evoking the postpollination response and that these stimuli are interpreted differently by the regulatory mechanisms of the ACC-synthase and -oxidase genes.

  5. Substrate specificity of flavin-dependent vanillyl-alcohol oxidase from Penicillium simplicissimum. Evidence for the production of 4-hydroxycinnamyl alcohols from 4-allylphenols.

    Science.gov (United States)

    Fraaije, M W; Veeger, C; van Berkel, W J

    1995-11-15

    The substrate specificity of the flavoprotein vanillyl-alcohol oxidase from Penicillium simplicissimum was investigated. Vanillyl-alcohol oxidase catalyzes besides the oxidation of 4-hydroxybenzyl alcohols, the oxidative deamination of 4-hydroxybenzylamines and the oxidative demethylation of 4-(methoxymethyl)phenols. During the conversion of vanillylamine to vanillin, a transient intermediate, most probably vanillylimine, is observed. Vanillyl-alcohol oxidase weakly interacts with 4-hydroxyphenylglycols and a series of catecholamines. These compounds are converted to the corresponding ketones. Both enantiomers of (nor)epinephrine are substrates for vanillyl-alcohol oxidase, but the R isomer is preferred. Vanillyl-alcohol oxidase is most active with chavicol and eugenol. These 4-allylphenols are converted to coumaryl alcohol and coniferyl alcohol, respectively. Isotopic labeling experiments show that the oxygen atom inserted at the C gamma atom of the side chain is derived from water. The 4-hydroxycinnamyl alcohol products and the substrate analog isoeugenol are competitive inhibitors of vanillyl alcohol oxidation. The binding of isoeugenol to the oxidized enzyme perturbs the optical spectrum of protein-bound FAD. pH-dependent binding studies suggest that vanillyl-alcohol oxidase preferentially binds the phenolate form of isoeugenol (pKa < 6, 25 degrees C). From this and the high pH optimum for turnover, a hydride transfer mechanism involving a p-quinone methide intermediate is proposed for the vanillyl-alcohol-oxidase-catalyzed conversion of 4-allylphenols.

  6. In Situ Enzymatically Generated Photoswitchable Oxidase Mimetics and Their Application for Colorimetric Detection of Glucose Oxidase.

    Science.gov (United States)

    Cao, Gen-Xia; Wu, Xiu-Ming; Dong, Yu-Ming; Li, Zai-Jun; Wang, Guang-Li

    2016-07-09

    In this study, a simple and amplified colorimetric assay is developed for the detection of the enzymatic activity of glucose oxidase (GOx) based on in situ formation of a photoswitchable oxidase mimetic of PO₄(3-)-capped CdS quantum dots (QDs). GOx catalyzes the oxidation of 1-thio-β-d-glucose to give 1-thio-β-d-gluconic acid which spontaneously hydrolyzes to β-d-gluconic acid and H₂S; the generated H₂S instantly reacts with Cd(2+) in the presence of Na₃PO₄ to give PO₄(3-)-stabilized CdS QDs in situ. Under visible-light (λ ≥ 400 nm) stimulation, the PO₄(3-)-capped CdS QDs are a new style of oxidase mimic derived by producing some active species, such as h⁺, (•)OH, O₂(•-) and a little H₂O₂, which can oxidize the typical substrate (3,3,5,5-tetramethylbenzydine (TMB)) with a color change. Based on the GOx-triggered growth of the oxidase mimetics of PO₄(3-)-capped CdS QDs in situ, we developed a simple and amplified colorimetric assay to probe the enzymatic activity of GOx. The proposed method allowed the detection of the enzymatic activity of GOx over the range from 25 μg/L to 50 mg/L with a low detection limit of 6.6 μg/L. We believe the PO₄(3-)-capped CdS QDs generated in situ with photo-stimulated enzyme-mimicking activity may find wide potential applications in biosensors.

  7. Visualization of monoamine oxidase in human brain

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, J.S.; Volkow, N.D.; Wang, G.J.; Pappas, N.; Shea, C.; MacGregor, R.R.; Logan, J.

    1996-12-31

    Monoamine oxidase is a flavin enzyme which exists in two subtypes, MAO A and MAO B. In human brain MAO B predominates and is largely compartmentalized in cell bodies of serotonergic neurons and glia. Regional distribution of MAO B was determined by positron computed tomography with volunteers after the administration of deuterium substituted [11C]L-deprenyl. The basal ganglia and thalamus exhibited the greatest concentrations of MAO B with intermediate levels in the frontal cortex and cingulate gyrus while lowest levels were observed in the parietal and temporal cortices and cerebellum. We observed that brain MAO B increases with are in health normal subjects, however the increases were generally smaller than those revealed with post-mortem studies.

  8. An ultrafiltration assay for lysyl oxidase

    International Nuclear Information System (INIS)

    Shackleton, D.R.; Hulmes, D.J.

    1990-01-01

    A modification of the original microdistillation assay for lysyl oxidase is described in which Amicon C-10 microconcentrators are used to separate, by ultrafiltration, the 3H-labeled products released from a [4,5-3H]-lysine-labeled elastin substrate. Enzyme activity is determined by scintillation counting of the ultrafiltrate, after subtraction of radioactivity released in the presence of beta-aminopropionitrile, a specific inhibitor of the enzyme. Conditions are described which optimize both the sensitivity and the efficient use of substrate. The assay shows linear inhibition of activity in up to 1 M urea; hence, as the enzyme is normally diluted in the assay, samples in 6 M urea can be assayed directly, without prior dialysis, and corrected for partial inhibition. Comparable results are obtained when enzyme activity is assayed by ultrafiltration or microdistillation. The assay is simple and convenient and, by using disposable containers throughout, it eliminates the need for time-consuming decontamination of radioactive glassware

  9. Quantitation of immunoadsorbed flavoprotein oxidases by luminol-mediated chemiluminescence.

    Science.gov (United States)

    Hinkkanen, A; Maly, F E; Decker, K

    1983-04-01

    The detection of the flavoenzymes 6-hydroxy-L-nicotine oxidase and 6-hydroxy-D-nicotine oxidase at the sub-femtomol level was achieved by coupling the reaction of the immunoadsorbed proteins to the peroxidase-catalysed oxidation of luminol. The H2O2-producing oxidases retained their full activity when bound to the respective immobilized antibodies. This fact allowed the concentration of the enzymes from very dilute solutions and the quantitative assay of their activities in the microU range. Due to strict stereoselectivity and the absence of immunological cross-reactivity, the two flavoproteins could be determined in the same solution. This method was used to measure the 6-hydroxy-D-nicotine oxidase and 6-hydroxy-L-nicotine oxidase activities in Escherichia coli RR1 and different Arthrobacter strains cultured under non-inducing conditions. The same activity ratio of 6-hydroxy-L-nicotine oxidase/6-hydroxy-D-nicotine oxidase as in D L-nicotine-induced cells of A. oxidans was observed in non-induced wild type and in riboflavin-requiring (rf-) mutant cells of this aerob.

  10. Interference of aldehyde metabolizing enzyme with diamine oxidase/histaminase/activity as determined by /sup 14/C putrescine method

    Energy Technology Data Exchange (ETDEWEB)

    Fogel, W A [Polish Academy of Sciences, Cracow (Poland). Inst. of Pharmacology; Bieganski, T; Wozniak, J; Maslinski, C

    1978-01-01

    The ..delta../sup 1/ pyrroline formation, as an indicator of diamine oxidase activity according to Okuyama and Kobayashi /sup 14/C putrescine test (1961, Archs Biochem. Biophys., vol.95, 242), has been investigated in several tissue homogenates. When guinea pig liver homogenate was used as a source of enzyme in the presence of aldehyde dehydrogenase inhibitors chlorate hydrate and acetaldehyde the level of formation ..delta../sup 1/ pyrroline was strongly increased in a dose-dependent manner. Also inhibition of aldehyde reductase by phenobarbital enhanced ..delta../sup 1/ pyrroline formation, but to a lesser degree. In other tissues, with very high initial diamine oxidase activity (rat intestine, dog kidney) or with very low diamine oxidase activity (guinea pig skin, dog liver) the influence of these inhibitors was only slight. Pyrazole, an inhibitor of alcohol dehydrogenase exerted only a small effect on ..delta../sup 1/ pyrroline formation. All aldehyde-metabolizing enzymes inhibitors, except pyrazole, were without effect on purified pea seddling and hog kidney diamine oxidases. The use of aldehyde-metabolizing enzymes inhibitors may help to reveal the real values of diamine oxidase activity, when tissues homogenates are used as a source of enzyme.

  11. Interference of aldehyde metabolizing enzyme with diamine oxidase/histaminase/activity as determined by 14C putrescine method

    International Nuclear Information System (INIS)

    Fogel, W.A.; Bieganski, T.; Wozniak, J.; Maslinski, C.

    1978-01-01

    The Δ 1 pyrroline formation, as an indicator of diamine oxidase activity according to Okuyama and Kobayashi 14 C putrescine test (1961, Archs Biochem. Biophys., vol.95, 242), has been investigated in several tissue homogenates. When guinea pig liver homogenate was used as a source of enzyme in the presence of aldehyde dehydrogenase inhibitors chlorate hydrate and acetaldehyde the level of formation Δ 1 pyrroline was strongly increased in a dose-dependent manner. Also inhibition of aldehyde reductase by phenobarbital enhanced Δ 1 pyrroline formation, but to a lesser degree. In other tissues, with very high initial diamine oxidase activity (rat intestine, dog kidney) or with very low diamine oxidase activity (guinea pig skin, dog liver) the influence of these inhibitors was only slight. Pyrazole, an inhibitor of alcohol dehydrogenase exerted only a small effect on Δ 1 pyrroline formation. All aldehyde-metabolizing enzymes inhibitors, except pyrazole, were without effect on purified pea seddling and hog kidney diamine oxidases. The use of aldehyde-metabolizing enzymes inhibitors may help to reveal the real values of diamine oxidase activity, when tissues homogenates are used as a source of enzyme. (author)

  12. IAA oxidase activity in relation to adventitious root formation on stem cuttings of some forest tree species. [Salix tetrasperma, Populus Robusta, Hibiscus rosa-sinensis, Eucalyptus citriodora

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, M.P.; Nanda, K.K.

    1981-01-01

    In rooting tests with stem cuttings, IAA oxidase activity was found to be very high in Salix tetrasperma and Populus 'Robusta' both of which rooted profusely, less in Hibiscus rosa-sinensis which rooted but weakly and insignificant in Eucalyptus citriodora, which did not root at all. Proteins extracted from the stem cuttings of E. citriodora inhibited IAA oxidase activity, and also root formation on hypocotyl cuttings of Phaseolus mungo.

  13. Adaptive evolution of cytochrome c oxidase: Infrastructure for a carnivorous plant radiation

    OpenAIRE

    Jobson, Richard W.; Nielsen, Rasmus; Laakkonen, Liisa; Wikström, Mårten; Albert, Victor A.

    2004-01-01

    Much recent attention in the study of adaptation of organismal form has centered on developmental regulation. As such, the highly conserved respiratory machinery of eukaryotic cells might seem an unlikely target for selection supporting novel morphologies. We demonstrate that a dramatic molecular evolutionary rate increase in subunit I of cytochrome c oxidase (COX) from an active-trapping lineage of carnivorous plants is caused by positive Darwinian selection. Bladderworts (Utricularia) trap ...

  14. Oxidized low-density lipoproteins upregulate proline oxidase to initiate ROS-dependent autophagy

    OpenAIRE

    Zabirnyk, Olga; Liu, Wei; Khalil, Shadi; Sharma, Anit; Phang, James M.

    2009-01-01

    Epidemiological studies showed that high levels of oxidized low-density lipoproteins (oxLDLs) are associated with increased cancer risk. We examined the direct effect of physiologic concentrations oxLDL on cancer cells. OxLDLs were cytotoxic and activate both apoptosis and autophagy. OxLDLs have ligands for peroxisome proliferator-activated receptor gamma and upregulated proline oxidase (POX) through this nuclear receptor. We identified 7-ketocholesterol (7KC) as a main component responsible ...

  15. Effect of a heme oxygenase-1 inducer on NADPH oxidase ...

    African Journals Online (AJOL)

    Effect of a heme oxygenase-1 inducer on NADPH oxidase expression in ... and immunohistochemistry of hepatic NOX1 and NOX4 were investigated in week 4. ... (HO-1 inhibitor) administration caused upregulation of NOX gene expression ...

  16. Structure and activity of Aspergillus nidulans copper amine oxidase

    DEFF Research Database (Denmark)

    McGrath, Aaron P; Mithieux, Suzanne M; Collyer, Charles A

    2011-01-01

    Aspergillus nidulans amine oxidase (ANAO) has the unusual ability among the family of copper and trihydroxyphenylalanine quinone-containing amine oxidases of being able to oxidize the amine side chains of lysine residues in large peptides and proteins. We show here that in common with the related...... enzyme from the yeast Pichia pastoris, ANAO can promote the cross-linking of tropoelastin and oxidize the lysine residues in α-casein proteins and tropoelastin. The crystal structure of ANAO, the first for a fungal enzyme in this family, has been determined to a resolution of 2.4 Å. The enzyme is a dimer...... with the archetypal fold of a copper-containing amine oxidase. The active site is the most open of any of those of the structurally characterized enzymes in the family and provides a ready explanation for its lysine oxidase-like activity....

  17. Gene cloning and characterization of NADH oxidase from ...

    African Journals Online (AJOL)

    use

    2011-12-07

    Dec 7, 2011 ... potent inhibitors of NADH oxidases, silver nitrate and potassium cyanide did not show any significant ... anaerobes, a class of organisms that have not been ... DNA and amino acid sequence analyses were performed using.

  18. An intron capture strategy used to identify and map a lysyl oxidase-like gene on chromosome 9 in the mouse

    Energy Technology Data Exchange (ETDEWEB)

    Wydner, K.S.; Passmore, H.C. [Rutgers Univ., Piscataway, NJ (United States); Kim, Houngho; Csiszar, K.; Boyd, C.D. [UMDNJ, New Brunswick, NJ (United States)

    1997-03-01

    An intron capture strategy involving use of polymerase chain reaction was used to identify and map the mouse homologue of a human lysyl oxidase-like gene (LOXL). Oligonucleotides complementary to conserved domains within exons 4 and 5 of the human lysyl oxidase-like gene were used to amplify the corresponding segment from mouse genomic DNA. Sequencing of the resulting mouse DNA fragment of approximately 1 kb revealed that the exon sequences at the ends of the amplified fragment are highly homologous (90% nucleotide identity) to exons 4 and 5 of the human lysyl oxidase-like gene. An AluI restriction site polymorphism within intron 4 was used to map the mouse lysyl oxidase-like gene (Loxl) to mouse Chromosome 9 in a region that shares linkage conservation with human chromosome 15q24, to which the LOXL was recently mapped. 22 refs., 3 figs.

  19. Effect of gamma irradiation on aspergillus niger for enhanced production of glucose oxidase

    International Nuclear Information System (INIS)

    Zia, M.A.; Rasul, S.

    2012-01-01

    Developing countries have a high prevalence of diabetes and their populations are suffering from associated adverse factors. Such a frequency requires more effective diagnosis, mostly achieved by glucose diagnostic kits. Although high priced kits are available in market but local production of such kits can be highly cost effective and may confer the decline in incidence of the disease. Glucose oxidase is the key enzyme for the determination of glucose in such analytical tools. Enhanced production of glucose oxidase was performed by mutagenesis of Aspergillus niger by gamma irradiation. A dose of 80 krad was found as optimum for derivation of positive mutant strains. Following the screening by triton X-100 and 2-deoxy-D-glucose, the selected strains A. niger G-80-A, A. niger G-80-B and A. niger G-80-C showed 27.5, 23.20 and 20.55 UmL/sub -1/ glucose oxidase activity in enzyme diffusion zone test; which is much higher to parental strain (7.5 UmL/sup -1/). A. niger G-80-A was subjected to submerged fermentation and obtained highest yields after 36 h, at CSL 2%, pH 6.5, 30 degree C, KH/sub 2/PO/sub 4/ 0.8% and urea 0.3%. Partial purification by ammonium sulfate resulted in 175 UmL/sup -1/ of glucose oxidase activity after dialysis. Kinetic parameters like optimum pH, temperature, K/sub m/ and V/sub max/ were found to be 6.0 (180 +- 2 UmL/sup -1/), 30 degree C (185 +- 0.5 UmL/sup -1/), 5.26 mM and 400 U mL/sup -1/, respectively. Active inhibition of the enzyme by increasing concentration of PLP in reaction mixture confirmed the presence of functional lysyl residue on the active site of enzyme. (author)

  20. Confirmation of a blocked amino terminus of sulfhydryl oxidase

    International Nuclear Information System (INIS)

    Janolino, V.G.; Morrison-Rowe, S.J.; Swaisgood, H.E.

    1990-01-01

    The isolation of sulfhydryl oxidase from bovine milk in a suitably pure form for sequencing was carried out by transient covalent affinity chromatography of diafiltered whey using cysteinylsuccinamidopropyl-glass as matrix. The glutathione-eluted proteins were separated by SDS-PAGE. By radiolabeling the affinity chromatography-purified enzyme with [ 14 C]iodoacetate before subjecting to SDS-PAGE, the sulfhydryl oxidase band was identified, because sulfhydryl oxidase is known to be inactivated by alkylation of one sulfhydryl group per mole. The results confirmed that sulfhydryl oxidase corresponds to the 85 (± 5)-kDa band observed on SDS-PAGE. The protein band corresponding to radiolabeled sulfhydryl oxidase was recovered from SDS-PAGE gels by electrophoretic elution and by electroblotting on polyvinylidene difluoride membrane and subjected to gas phase sequencing. Precautions were taken during electrophoretic elution to prevent reactions that result in N-terminal blocking. Both methods of protein recovery yielded negative results when subjected to sequence analysis indicating that the N-terminus of sulfhydryl oxidase is blocked

  1. Carbon fiber microelectrodes modified with carbon nanotubes as a new support for immobilization of glucose oxidase

    International Nuclear Information System (INIS)

    Wen, H.; Nallathambi, V.; Chakraborty, D.; Barton, S.C.

    2011-01-01

    Carboxylated carbon nanotubes were coated onto carbon microfiber electrodes to create a micron-scale bioelectrode. This material has a high surface area and can serve as a support for immobilization of enzymes such as glucose oxidase. A typical carbon nanotube loading of 13 μg cm -1 yields a coating thickness of 17 μm and a 2000-fold increase in surface capacitance. The modified electrode was further coated with a biocatalytic hydrogel composed of a conductive redox polymer, glucose oxidase, and a crosslinker to create a glucose bioelectrode. The current density on oxidation of glucose is 16.6 mA cm-2 at 0.5 V (vs. Ag/AgCl) in oxygen-free glucose solution. We consider this approach to be useful for designing and characterizing surface treatments for carbon mats and papers by mimicking their local microenvironment. (author)

  2. Molecular Modeling of Peroxidase and Polyphenol Oxidase: Substrate Specificity and Active Site Comparison

    Directory of Open Access Journals (Sweden)

    Lalida Shank

    2010-09-01

    Full Text Available Peroxidases (POD and polyphenol oxidase (PPO are enzymes that are well known to be involved in the enzymatic browning reaction of fruits and vegetables with different catalytic mechanisms. Both enzymes have some common substrates, but each also has its specific substrates. In our computational study, the amino acid sequence of grape peroxidase (ABX was used for the construction of models employing homology modeling method based on the X-ray structure of cytosolic ascorbate peroxidase from pea (PDB ID:1APX, whereas the model of grape polyphenol oxidase was obtained directly from the available X-ray structure (PDB ID:2P3X. Molecular docking of common substrates of these two enzymes was subsequently studied. It was found that epicatechin and catechin exhibited high affinity with both enzymes, even though POD and PPO have different binding pockets regarding the size and the key amino acids involved in binding. Predicted binding modes of substrates with both enzymes were also compared. The calculated docking interaction energy of trihydroxybenzoic acid related compounds shows high affinity, suggesting specificity and potential use as common inhibitor to grape ascorbate peroxidase and polyphenol oxidase.

  3. Thermal Characterization of Purified Glucose Oxidase from A Newly Isolated Aspergillus Niger UAF-1

    Science.gov (United States)

    Anjum Zia, Muhammad; Khalil-ur-Rahman; K. Saeed, Muhammad; Andaleeb, Fozia; I. Rajoka, Muhammad; A. Sheikh, Munir; A. Khan, Iftikhar; I. Khan, Azeem

    2007-01-01

    An intracellular glucose oxidase was isolated from the mycelium extract of a locally isolated strain of Aspergillus niger UAF-1. The enzyme was purified to a yield of 28.43% and specific activity of 135 U mg−1 through ammonium sulfate precipitation, anion exchange and gel filtration chromatography. The enzyme showed high affinity for D-glucose with a Km value of 2.56 mM. The enzyme exhibited optimum catalytic activity at pH 5.5. Temperature optimum for glucose oxidase, catalyzed D-glucose oxidation was 40°C. The enzyme showed a high thermostability having a half-life 30 min, enthalpy of denaturation 99.66 kJ mol−1 and free energy of denaturation 103.63 kJ mol−1. These characteristics suggest the use of glucose oxidase from Aspergillus niger UAF-1 as an analytical reagent and in the design of biosensors for clinical, biochemical and diagnostic assays. PMID:18193107

  4. Characterization of polyphenol oxidase from blueberry (Vaccinium corymbosum L.).

    Science.gov (United States)

    Siddiq, M; Dolan, K D

    2017-03-01

    Polyphenol oxidase (PPO) was extracted and characterized from high-bush blueberries. PPO showed an optimum activity at pH 6.1-6.3 and 35°C, with the enzyme showing significant activity over a wide temperature range (25-60°C). Catechol was the most readily oxidized substrate followed by 4-methylcatechol, DL-DOPA, and dopamine. Blueberry PPO showed a K m of 15mM and V max of 2.57 ΔA 420 nm/min×10 -1 , determined with catechol. PPO was completely inactivated in 20min at 85°C, however, after 30minat 75°C it showed about 10% residual activity. Thermal treatment at 55 and 65°C for 30min resulted in the partial inactivation of PPO. Ascorbic acid, sodium diethyldithiocarbamic acid, L-cysteine, and sodium metabisulfite were effective inhibitors of PPO at 1.0mM. Benzoic acid and cinnamic acid series inhibitors showed relatively weak inhibition of PPO (21.8-27.6%), even at as high as 2.0mM concentration. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Cytochemical localization of catalase and several hydrogen peroxide-producing oxidases in the nucleoids and matrix of rat liver peroxisomes

    NARCIS (Netherlands)

    Veenhuis, M.; Wendelaar Bonga, S.E.

    1979-01-01

    The distribution of catalase, amino acid oxidase, α-hydroxy acid oxidase, urate oxidase and alcohol oxidase was studied cytochemically in rat hepatocytes. The presence of catalase was demonstrated with the conventional diaminobenzidine technique. Oxidase activities were visualized with methods based

  6. Serum diamine oxidase activity in patients with histamine intolerance.

    Science.gov (United States)

    Manzotti, G; Breda, D; Di Gioacchino, M; Burastero, S E

    2016-03-01

    Intolerance to various foods, excluding bona fide coeliac disease and lactose intolerance, represents a growing cause of patient visits to allergy clinics.Histamine intolerance is a long-known, multifaceted clinical condition triggered by histamine-rich foods and alcohol and/or by drugs that liberate histamine or block diamine oxidase (DAO), the main enzyme involved in the metabolism of ingested histamine. Histamine limitation diets impose complex, non-standardized restrictions that may severely impact the quality of life of patients. We retrospectively evaluated 14 patients who visited allergy outpatient facilities in northern Italy with a negative diagnosis for IgE-mediated food hypersensitivity, coeliac disease, conditions related to gastric hypersecretion, and systemic nickel hypersensitivity, and who previously underwent a histamine limitation diet with benefits for their main symptoms. Serum diamine oxidase levels and the clinical response to diamine oxidase supplementation were investigated. We found that 10 out of 14 patients had serum DAO activityintolerance. Moreover, 13 out of 14 patients subjectively reported a benefit in at least one of the disturbances related to food intolerances following diamine oxidase supplementation. The mean value (±SD) of diamine oxidase activity in the cohort of patients with histamine intolerance symptoms was 7.04±6.90 U/mL compared to 39.50±18.16 U/mL in 34 healthy controls (P=0.0031). In patients with symptoms triggered by histamine-rich food, measuring the serum diamine oxidase activity can help identify subjects who can benefit from a histamine limitation diet and/or diamine oxidase supplementation.Properly designed, controlled studies investigating histamine intolerance that include histamine provocation are indispensable for providing insights into the area of food intolerances, which are currently primarily managed with non-scientific approaches in Italy. © The Author(s) 2015.

  7. Improving Glyphosate Oxidation Activity of Glycine Oxidase from Bacillus cereus by Directed Evolution

    Science.gov (United States)

    Zhan, Tao; Zhang, Kai; Chen, Yangyan; Lin, Yongjun; Wu, Gaobing; Zhang, Lili; Yao, Pei; Shao, Zongze; Liu, Ziduo

    2013-01-01

    Glyphosate, a broad spectrum herbicide widely used in agriculture all over the world, inhibits 5-enolpyruvylshikimate-3-phosphate synthase in the shikimate pathway, and glycine oxidase (GO) has been reported to be able to catalyze the oxidative deamination of various amines and cleave the C-N bond in glyphosate. Here, in an effort to improve the catalytic activity of the glycine oxidase that was cloned from a glyphosate-degrading marine strain of Bacillus cereus (BceGO), we used a bacteriophage T7 lysis-based method for high-throughput screening of oxidase activity and engineered the gene encoding BceGO by directed evolution. Six mutants exhibiting enhanced activity toward glyphosate were screened from two rounds of error-prone PCR combined with site directed mutagenesis, and the beneficial mutations of the six evolved variants were recombined by DNA shuffling. Four recombinants were generated and, when compared with the wild-type BceGO, the most active mutant B3S1 showed the highest activity, exhibiting a 160-fold increase in substrate affinity, a 326-fold enhancement in catalytic efficiency against glyphosate, with little difference between their pH and temperature stabilities. The role of these mutations was explored through structure modeling and molecular docking, revealing that the Arg51 mutation is near the active site and could be an important residue contributing to the stabilization of glyphosate binding, while the role of the remaining mutations is unclear. These results provide insight into the application of directed evolution in optimizing glycine oxidase function and have laid a foundation for the development of glyphosate-tolerant crops. PMID:24223901

  8. Improving glyphosate oxidation activity of glycine oxidase from Bacillus cereus by directed evolution.

    Directory of Open Access Journals (Sweden)

    Tao Zhan

    Full Text Available Glyphosate, a broad spectrum herbicide widely used in agriculture all over the world, inhibits 5-enolpyruvylshikimate-3-phosphate synthase in the shikimate pathway, and glycine oxidase (GO has been reported to be able to catalyze the oxidative deamination of various amines and cleave the C-N bond in glyphosate. Here, in an effort to improve the catalytic activity of the glycine oxidase that was cloned from a glyphosate-degrading marine strain of Bacillus cereus (BceGO, we used a bacteriophage T7 lysis-based method for high-throughput screening of oxidase activity and engineered the gene encoding BceGO by directed evolution. Six mutants exhibiting enhanced activity toward glyphosate were screened from two rounds of error-prone PCR combined with site directed mutagenesis, and the beneficial mutations of the six evolved variants were recombined by DNA shuffling. Four recombinants were generated and, when compared with the wild-type BceGO, the most active mutant B3S1 showed the highest activity, exhibiting a 160-fold increase in substrate affinity, a 326-fold enhancement in catalytic efficiency against glyphosate, with little difference between their pH and temperature stabilities. The role of these mutations was explored through structure modeling and molecular docking, revealing that the Arg(51 mutation is near the active site and could be an important residue contributing to the stabilization of glyphosate binding, while the role of the remaining mutations is unclear. These results provide insight into the application of directed evolution in optimizing glycine oxidase function and have laid a foundation for the development of glyphosate-tolerant crops.

  9. Biological Effects of Potato Plants Transformation with Glucose Oxidase Gene and their Resistance to Hyperthermia

    Directory of Open Access Journals (Sweden)

    O.I. Grabelnych

    2017-02-01

    Full Text Available It is known that regulation of plant tolerance to adverse environmental factors is connected with short term increase of the concentration of endogenous reactive oxygen species (ROS, which are signalling molecules for the induction of protective mechanisms. Introduction and expression of heterologous gox gene, which encodes glucose oxidase enzyme in plant genome, induce constantly higher content of hydrogen peroxide in plant tissues. It is not known how the introduction of native or modified gox gene affects the plant resistance to high-temperature stress, one of the most commonly used model for the study of stress response and thermal tolerance. In this study, we investigated biological effects of transformation and evaluated the resistance to temperature stress of potato plants with altered levels of glucose oxidase expression. Transformation of potato plants by gox gene led to the more early coming out from tuber dormancy of transformed plants and slower growth rate. Transformants containing the glucose oxidase gene were more sensitive to lethal thermal shock (50 °C, 90 min than the transformant with the empty vector (pBI or untransformed plants (CK. Pre-heating of plants at 37 °C significantly weakened the damaging effect of lethal thermal shock. This attenuation was more significant in the non-transformed plants.

  10. Feasibility of converting lactic acid to ethanol in food waste fermentation by immobilized lactate oxidase

    International Nuclear Information System (INIS)

    Ma, Hong-zhi; Xing, Yi; Yu, Miao; Wang, Qunhui

    2014-01-01

    Highlights: • Residue lactic acid in food waste could be converted to pyruvic acid. • Calcium alginate immobilized the lactate oxidase with high pH and thermal stability. • Immobilized enzyme could convert 70% lactic acid to pyruvic acid. • Ethanol yield could be increased by 20% with lactate oxidase added. - Abstract: Adoption of lactic acid bacteria (LAB) into ethanol fermentation from food waste can replace the sterilization process. However, LAB inoculation will convert part of the substrate into lactic acid (LA), not ethanol. This study adopted lactate oxidase to convert the produced LA to pyruvate, and then ethanol fermentation was carried out. The immobilization enzyme was utilized, and corresponding optimum conditions were determined. Results showed that calcium alginate could successfully immobilize the enzyme and improve pH and thermal stability. The optimum pH and temperature were 6.2 and 55 °C, respectively. The utilization of immobilized enzyme with catalytic time of 5 h could convert 70% LA to pyruvate, and the addition of enzyme increased the ethanol yield by 20% more than that of the control. The process could be applied in food waste storage and can help in reducing carbon source consumption

  11. Cell Wall Amine Oxidases: New Players in Root Xylem Differentiation under Stress Conditions

    Directory of Open Access Journals (Sweden)

    Sandip A. Ghuge

    2015-07-01

    Full Text Available Polyamines (PAs are aliphatic polycations present in all living organisms. A growing body of evidence reveals their involvement as regulators in a variety of physiological and pathological events. They are oxidatively deaminated by amine oxidases (AOs, including copper amine oxidases (CuAOs and flavin adenine dinucleotide (FAD-dependent polyamine oxidases (PAOs. The biologically-active hydrogen peroxide (H2O2 is a shared compound in all of the AO-catalyzed reactions, and it has been reported to play important roles in PA-mediated developmental and stress-induced processes. In particular, the AO-driven H2O2 biosynthesis in the cell wall is well known to be involved in plant wound healing and pathogen attack responses by both triggering peroxidase-mediated wall-stiffening events and signaling modulation of defense gene expression. Extensive investigation by a variety of methodological approaches revealed high levels of expression of cell wall-localized AOs in root xylem tissues and vascular parenchyma of different plant species. Here, the recent progresses in understanding the role of cell wall-localized AOs as mediators of root xylem differentiation during development and/or under stress conditions are reviewed. A number of experimental pieces of evidence supports the involvement of apoplastic H2O2 derived from PA oxidation in xylem tissue maturation under stress-simulated conditions.

  12. Monoamine Oxidase B Inhibitors in Parkinson's Disease.

    Science.gov (United States)

    Dezsi, Livia; Vecsei, Laszlo

    2017-01-01

    Parkinson's disease (PD) is a neurodegenerative disorder with a prevalence increasing with age. Oxidative stress and glutamate toxicity are involved in its pathomechanism. There are still many unmet needs of PD patients, including the alleviation of motor fluctuations and dyskinesias, and the development of therapies with neuroprotective potential. To give an overview of the pharmacological properties, the efficacy and safety of the monoamine oxidase B (MAO-B) inhibitors in the treatment of PD, with special focus on the results of randomized clinical trials. A literature search was conducted in PubMed for 'PD treatment', 'MAO-B inhibitors', 'selegiline', 'rasagiline', 'safinamide' and 'clinical trials' with 'MAO-B inhibitors' in 'Parkinson' disease'. MAO-B inhibitors have a favorable pharmacokinetic profile, improve the dopamine deficient state and may have neuroprotective properties. Safinamide exhibits an anti-glutamatergic effect as well. When applied as monotherapy, MAO-B inhibitors provide a modest, but significant improvement of motor function and delay the need for levodopa. Rasagiline and safinamide were proven safe and effective when added to a dopamine agonist in early PD. As add-on to levodopa, MAO-B inhibitors significantly reduced off-time and were comparable in efficacy to COMT inhibitors. Improvements were achieved as regards certain non-motor symptoms as well. Due to the efficacy shown in clinical trials and their favorable side-effect profile, MAO-B inhibitors are valuable drugs in the treatment of PD. They are recommended as monotherapy in the early stages of the disease and as add-on therapy to levodopa in advanced PD. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  13. Monoamine oxidase and agitation in psychiatric patients.

    Science.gov (United States)

    Nikolac Perkovic, Matea; Svob Strac, Dubravka; Nedic Erjavec, Gordana; Uzun, Suzana; Podobnik, Josip; Kozumplik, Oliver; Vlatkovic, Suzana; Pivac, Nela

    2016-08-01

    Subjects with schizophrenia or conduct disorder display a lifelong pattern of antisocial, aggressive and violent behavior and agitation. Monoamine oxidase (MAO) is an enzyme involved in the degradation of various monoamine neurotransmitters and neuromodulators and therefore has a role in various psychiatric and neurodegenerative disorders and pathological behaviors. Platelet MAO-B activity has been associated with psychopathy- and aggression-related personality traits, while variants of the MAOA and MAOB genes have been associated with diverse clinical phenotypes, including aggressiveness, antisocial problems and violent delinquency. The aim of the study was to evaluate the association of platelet MAO-B activity, MAOB rs1799836 polymorphism and MAOA uVNTR polymorphism with severe agitation in 363 subjects with schizophrenia and conduct disorder. The results demonstrated significant association of severe agitation and smoking, but not diagnosis or age, with platelet MAO-B activity. Higher platelet MAO-B activity was found in subjects with severe agitation compared to non-agitated subjects. Platelet MAO-B activity was not associated with MAOB rs1799836 polymorphism. These results suggested the association between increased platelet MAO-B activity and severe agitation. No significant association was found between severe agitation and MAOA uVNTR or MAOB rs1799836 polymorphism, revealing that these individual polymorphisms in MAO genes are not related to severe agitation in subjects with schizophrenia and conduct disorder. As our study included 363 homogenous Caucasian male subjects, our data showing this negative genetic association will be a useful addition to future meta-analyses. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. [Effect of Kaixinsan on monoamine oxidase activity].

    Science.gov (United States)

    Wang, Shi; Dong, Xian-Zhe; Tan, Xiao; Wang, Yu-Ning; Liu, Ping

    2016-05-01

    To observe the effect of antidepressant medicine prescription, Kaixinsan (KXS) on monoamine oxidase (MAO) activity, and explore the mechanism of KXS in elevating the levels of monoamine neurotransmitter from the perspective of metabolism, in vitro enzyme reaction system and C6 neuroglial cells, the effect of KXS at different concentrations on MAO-A and MAO-B activity was observed. In animal studies, the effect of KXS at different concentrations on MAO-A and MAO-B activities of brain mitochondrialin normal rats and solitary chronic unpredictable moderate stress (CMS) model rats after intragastric administration for 1, 2, 3 weeks. Results showed that 10 g•L⁻¹ KXS could significantly reduce the activity of MAO-A and MAO-B in enzyme reaction system; and in C6 cells, KXS within 0.625-10 g•L⁻¹ concentration range had no significant effect on the activity of MAO-A, but had obvious inhibitory effect on the activity of MAO-B in a dose dependent manner. KXS had no significant effect on the activity of MAO-A and MAO-B in brains of normal rats after action for 1, 2, 3 weeks. After 2 and 3 weeks treatment with 338 mg•kg⁻¹ dose KXS, MAO-A activity in the brain of CMS rats was decreased as compared with the model group (PMAO-B activity after 1, 2, 3 weeks of treatment. The results indicated that KXS had certain effect on in vitro MAO-A and MAO-B activity, had no effect on brain MAO-A and MAO-B activity in vivo in normal rats, and had certain inhibitory effect on MAO-A activity in brains of CMS rats. Copyright© by the Chinese Pharmaceutical Association.

  15. Urate oxidase for the prevention and treatment of tumour lysis syndrome in children with cancer.

    Science.gov (United States)

    Cheuk, Daniel Kl; Chiang, Alan Ks; Chan, Godfrey Cf; Ha, Shau Yin

    2017-03-08

    % CI 1.29 to 64.00; P = 0.03).Another included RCT, with 30 participants, compared different doses of rasburicase (0.2 mg/kg versus 0.15 mg/kg). The primary outcome was not evaluated. No clear evidence of a difference in mortality (all-cause mortality (Fisher's exact test P = 1.0) and mortality due to TLS (no deaths in both groups)) and renal failure (no renal failure in both groups) was identified. It demonstrated no clear evidence of a difference in uric acid normalisation (RR 1.07, 95% CI 0.89 to 1.28; P = 0.49) and uric acid level at four hours (MD 8.10%, 95% CI -0.99% to 17.19%; P = 0.08). Common adverse events of urate oxidase included hypersensitivity, haemolysis, and anaemia, but no clear evidence of a difference between treatment groups was identified (RR 0.54, 95% CI 0.12 to 2.48; P = 0.42).The quality of evidence ranks from very low to low because of imprecise results, and all included trials were highly susceptible to biases. Although urate oxidase might be effective in reducing serum uric acid, it is unclear whether it reduces clinical TLS, renal failure, or mortality. Adverse effects might be more common for urate oxidase compared with allopurinol. Clinicians should weigh the potential benefits of reducing uric acid and uncertain benefits of preventing mortality or renal failure from TLS against the potential risk of adverse effects.

  16. A study of monoamine oxidase activity in fetal membranes.

    Science.gov (United States)

    Sekizawa, A; Ishikawa, H; Morimoto, T; Hirose, K; Suzuki, A; Saito, H; Yanaihara, T; Arai, Y; Oguchi, K

    1996-05-01

    To study the role of decidual monoamine oxidase (MAO)-A and -B activities before delivery, the relationship between MAO activity in fetal membranes and catecholamine (CA) concentration in amniotic fluid (AF) was determined. Fetal membranes and AF were obtained at the time of elective Cesarean section (CS group, n = 11) and Cesarean section due to fetal distress without labor pains (FD group, n = 5). MAO-A and -B activities were radiometrically measured using 14C-5-hydroxytriptamine for MAO-A substrate and 14C-benzylamine for MAO-B substrate. CA concentrations in AF were measured by high performance liquid chromatograph with an electro-chemical detector. Both MAO-A and -B activities in decidua obtained from CS were significantly lower than those obtained from FD. Both norepinephrine (NE) and epinephrine (EP) concentrations were significantly lower in the CS group than the FD group. A significant positive correlation between decidual MAO-A activity and NE concentration in AF was observed. No significant correlation was observed between MAO-B activity and the concentration of NE in AF. There was no correlation between EP concentrations and MAO activities. These results suggest that CA concentration in AF may be related to the activity of MAO in fetal membranes, determined by certain physiological processes during pregnancy. It has been suggested that metabolism of monoamines in fetal membranes also plays an important role in reducing monoamine influx into maternal myometrium from the AF.

  17. Xanthine Oxidase Inhibitory Activity of a Plectranthus saccatus aqueous extract

    Directory of Open Access Journals (Sweden)

    Caldeira F

    2016-12-01

    Full Text Available Gout is a disease with high prevalence in developed countries, resulting from the deposition of uric acid crystals in various locations, particularly at the joints. The pharmacotherapeutic approach to chronic gout essentially consists of administration of uric acid-lowering agents. The main mechanism of action of these agents is the inhibition of xanthine oxidase (XO, the enzyme responsible for the formation of uric acid. The therapeutic alternatives available for this purpose are limited, thus justifying the interest of the discovery of potential new uric acidlowering drugs. In this regard, an aqueous extract of the plant Plectranthus saccatus has been studied for its ability to inhibit XO. The composition of the extract was determined by HPLC and rosmarinic acid was identified as the major constituent. Both the extract and rosmarinic acid have demonstrated the ability to inhibit the production of uric acid by interfering with XO activity. The results obtained herein support the continuation of the study of their uric acid-lowering properties in cell-based and in vivo models to further explore their potential in gout therapy.

  18. Calcium transport in vesicles energized by cytochrome oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Rosier, Randy N. [Univ. of Rochester, NY (United States)

    1979-01-01

    Experiments on the reconstitution of cytochrome oxidase into phospholipid vesicles were carried out using techniques of selectivity energizing the suspensions with ascorbate and cytochrome c or ascorbate, PMS, and internally trapped cytochrome c. It was found that the K+ selective ionophore valinomycin stimulated the rate of respiration of cytochrome oxidase vesicles regardless of the direction of the K+ flux across the vesicle membranes. The stimulation occurred in the presence of protonophoric uncouplers and in the complete absence of potassium or in detergent-lysed suspensions. Gramicidin had similar effects and it was determined that the ionophores acted by specific interaction with cytochrome oxidase rather than by the previously assumed collapse of membrane potentials. When hydrophobic proteins and appropriate coupling factors were incorporated into the cytochrome oxidase, vesicles phosphorylation of ADP could be coupled to the oxidation reaction of cytochrome oxidase. Relatively low P:O, representing poor coupling of the system, were problematical and precluded measurements of protonmotive force. However the system was used to study ion translocation.

  19. Immobilization of xanthine oxidase on a polyaniline silicone support.

    Science.gov (United States)

    Nadruz, W; Marques, E T; Azevedo, W M; Lima-Filho, J L; Carvalho, L B

    1996-03-01

    A polyaniline silicone support to immobilize xanthine oxidase is proposed as a reactor coil to monitor the action of xanthine oxidase on hypoxanthine, xanthine and 6-mercaptopurine. A purified xanthine oxidase immobilized on this support lost 80% of the initial activity after 12 min of use. Co-immobilization of superoxide dismutase and catalase increased the stability of immobilized xanthine oxidase so that the derivative maintained 79% of its initial activity after 4.6 h of continuous use in which 1.5 mumol purine bases were converted by the immobilized enzyme system. There is no evidence of either polyaniline or protein leaching from the coil during 3 h of continuous use. When solutions (10 ml) of hypoxanthine, xanthine and 6-mercaptopurine were circulated individually through the xanthine oxidase-superoxide dismutase-catalase-polyaniline coil (1 mm internal diameter and 3 m in length, 3 ml internal volume) activities of 8.12, 11.17 and 1.09 nmol min-1 coil-1, respectively, were obtained. The advantages of the reactor configuration and the redox properties of the polymer, particularly with respect to immobilized oxidoreductases, make this methodology attractive for similar enzyme systems. This immobilized enzyme system using polyaniline-silicone as support converted 6-mercaptopurine to 6-thiouric acid with equal efficiency as resins based on polyacrylamide and polyamide 11.

  20. Prognostic relevance of cytochrome C oxidase in primary glioblastoma multiforme.

    Directory of Open Access Journals (Sweden)

    Corinne E Griguer

    Full Text Available Patients with primary glioblastoma multiforme (GBM have one of the lowest overall survival rates among cancer patients, and reliable biomarkers are necessary to predict patient outcome. Cytochrome c oxidase (CcO promotes the switch from glycolytic to OXPHOS metabolism, and increased CcO activity in tumors has been associated with tumor progression after chemotherapy failure. Thus, we investigated the relationship between tumor CcO activity and the survival of patients diagnosed with primary GBM. A total of 84 patients with grade IV glioma were evaluated in this retrospective cohort study. Cumulative survival was calculated by the Kaplan-Meier method and analyzed by the log-rank test, and univariate and multivariate analyses were performed with the Cox regression model. Mitochondrial CcO activity was determined by spectrophotometrically measuring the oxidation of cytochrome c. High CcO activity was detected in a subset of glioma tumors (∼30%, and was an independent prognostic factor for shorter progression-free survival and overall survival [P = 0.0087 by the log-rank test, hazard ratio = 3.57 for progression-free survival; P<0.001 by the log-rank test, hazard ratio = 10.75 for overall survival]. The median survival time for patients with low tumor CcO activity was 14.3 months, compared with 6.3 months for patients with high tumor CcO activity. High CcO activity occurs in a significant subset of high-grade glioma patients and is an independent predictor of poor outcome. Thus, CcO activity may serve as a useful molecular marker for the categorization and targeted therapy of GBMs.

  1. The Role of Aldehyde Oxidase and Xanthine Oxidase in the Biotransformation of a Novel Negative Allosteric Modulator of Metabotropic Glutamate Receptor Subtype 5

    Science.gov (United States)

    Morrison, Ryan D.; Blobaum, Anna L.; Byers, Frank W.; Santomango, Tammy S.; Bridges, Thomas M.; Stec, Donald; Brewer, Katrina A.; Sanchez-Ponce, Raymundo; Corlew, Melany M.; Rush, Roger; Felts, Andrew S.; Manka, Jason; Bates, Brittney S.; Venable, Daryl F.; Rodriguez, Alice L.; Jones, Carrie K.; Niswender, Colleen M.; Conn, P. Jeffrey; Lindsley, Craig W.; Emmitte, Kyle A.

    2012-01-01

    Negative allosteric modulation (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5) represents a therapeutic strategy for the treatment of childhood developmental disorders, such as fragile X syndrome and autism. VU0409106 emerged as a lead compound within a biaryl ether series, displaying potent and selective inhibition of mGlu5. Despite its high clearance and short half-life, VU0409106 demonstrated efficacy in rodent models of anxiety after extravascular administration. However, lack of a consistent correlation in rat between in vitro hepatic clearance and in vivo plasma clearance for the biaryl ether series prompted an investigation into the biotransformation of VU0409106 using hepatic subcellular fractions. An in vitro appraisal in rat, monkey, and human liver S9 fractions indicated that the principal pathway was NADPH-independent oxidation to metabolite M1 (+16 Da). Both raloxifene (aldehyde oxidase inhibitor) and allopurinol (xanthine oxidase inhibitor) attenuated the formation of M1, thus implicating the contribution of both molybdenum hydroxylases in the biotransformation of VU0409106. The use of 18O-labeled water in the S9 experiments confirmed the hydroxylase mechanism proposed, because 18O was incorporated into M1 (+18 Da) as well as in a secondary metabolite (M2; +36 Da), the formation of which was exclusively xanthine oxidase-mediated. This unusual dual and sequential hydroxylase metabolism was confirmed in liver S9 and hepatocytes of multiple species and correlated with in vivo data because M1 and M2 were the principal metabolites detected in rats administered VU0409106. An in vitro-in vivo correlation of predicted hepatic and plasma clearance was subsequently established for VU0409106 in rats and nonhuman primates. PMID:22711749

  2. NADPH Oxidase-Mediated ROS Production Determines Insulin's Action on the Retinal Microvasculature.

    Science.gov (United States)

    Kida, Teruyo; Oku, Hidehiro; Horie, Taeko; Matsuo, Junko; Kobayashi, Takatoshi; Fukumoto, Masanori; Ikeda, Tsunehiko

    2015-10-01

    To determine whether insulin induces nitric oxide (NO) formation in retinal microvessels and to examine the effects of high glucose on the formation of NO. Freshly isolated rat retinal microvessels were incubated in normal (5.5 mM) or high (20 mM) glucose with or without insulin (100 nM). The levels of insulin-induced NO and reactive oxygen species (ROS) in the retinal microvessels were determined semiquantitatively using fluorescent probes, 4,5-diaminofluorescein diacetate, and hydroethidine, respectively, and a laser scanning confocal microscope. The insulin-induced changes of NO in rat retinal endothelial cells and pericytes cultured at different glucose concentrations (5.5 and 25 mM) were determined using flow cytometry. Nitric oxide synthase (NOS) protein levels were determined by Western blot analysis; intracellular levels of ROS were determined using fluorescence-activated cell sorting (FACS) analysis of ethidium fluorescence; and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase RNA expression was quantified using real-time PCR. Exposure of microvessels to insulin under normal glucose conditions led to a significant increase in NO levels; however, this increase was significantly suppressed when the microvessels were incubated under high glucose conditions. Intracellular levels of ROS were significantly increased in both retinal microvessels and cultured microvascular cells under high glucose conditions. The expression of NOS and NADPH oxidase were significantly increased in endothelial cells and pericytes under high glucose conditions. The increased formation of NO by insulin and its suppression by high glucose conditions suggests that ROS production mediated by NADPH oxidase is important by insulin's effect on the retinal microvasculature.

  3. Fluorescent Probes for Analysis and Imaging of Monoamine Oxidase Activity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dokyoung; Jun, Yong Woong; Ahn, Kyo Han [POSTECH, Pohang (Korea, Republic of)

    2014-05-15

    Monoamine oxidases catalyze the oxidative deamination of dietary amines and amine neurotransmitters, and assist in maintaining the homeostasis of the amine neurotransmitters in the brain. Dysfunctions of these enzymes can cause neurological and behavioral disorders including Parkinson's and Alzheimer's diseases. To understand their physiological roles, efficient assay methods for monoamine oxidases are essential. Reviewed in this Perspective are the recent progress in the development of fluorescent probes for monoamine oxidases and their applications to enzyme assays in cells and tissues. It is evident that still there is strong need for a fluorescent probe with desirable substrate selectivity and photophysical properties to challenge the much unsolved issues associated with the enzymes and the diseases.

  4. The use of galactose oxidase in lipid labeling

    International Nuclear Information System (INIS)

    Radin, N.S.; Evangelatos, G.P.

    1981-01-01

    Galactose oxidase can be used to oxidize the terminal carbon atom of lipids containing galactose or N-acetylgalactosamine, and the resultant aldehyde group can be reduced back to the original carbinol with radioactive borohydride. The efficiency of the first reaction has been investigated systematically by using [6- 3 H]galactosyl ceramide as substrate and measuring the amount of radioactive water formed. This enabled us to establish that the addition of catalase and peroxidase greatly speeded the oxidation, that phosphate and PIPES buffers were the best among those tested, that the reaction continued for 24 hr without a second addition of galactose oxidase, and that the optimum concentration of organic solvent (tetrahydrofuran) was 50%. The suggestion if made that a similar set of variables be studied for each lipid or nonlipid by the same basic technique: labeling by the oxidase/borohydride method and use of the resultant compound as substrate

  5. Extra virgin olive oil rich in polyphenols modulates VEGF-induced angiogenic responses by preventing NADPH oxidase activity and expression.

    Science.gov (United States)

    Calabriso, Nadia; Massaro, Marika; Scoditti, Egeria; D'Amore, Simona; Gnoni, Antonio; Pellegrino, Mariangela; Storelli, Carlo; De Caterina, Raffaele; Palasciano, Giuseppe; Carluccio, Maria Annunziata

    2016-02-01

    Previous studies have shown the antiinflammatory, antioxidant and antiangiogenic properties by pure olive oil polyphenols; however, the effects of olive oil phenolic fraction on the inflammatory angiogenesis are unknown. In this study, we investigated the effects of the phenolic fraction (olive oil polyphenolic extract, OOPE) from extra virgin olive oil and related circulating metabolites on the VEGF-induced angiogenic responses and NADPH oxidase activity and expression in human cultured endothelial cells. We found that OOPE (1-10 μg/ml), at concentrations achievable nutritionally, significantly reduced, in a concentration-dependent manner, the VEGF-induced cell migration, invasiveness and tube-like structure formation through the inhibition of MMP-2 and MMP-9. OOPE significantly (Pextra virgin olive oil, with high polyphenol content, decreased VEGF-induced NADPH oxidase activity and Nox4 expression, as well as, MMP-9 expression, as compared with fasting control serum. Overall, native polyphenols and serum metabolites of extra virgin olive oil rich in polyphenols are able to lower the VEGF-induced angiogenic responses by preventing endothelial NADPH oxidase activity and decreasing the expression of selective NADPH oxidase subunits. Our results provide an alternative mechanism by which the consumption of olive oil rich in polyphenols may account for a reduction of oxidative stress inflammatory-related sequelae associated with chronic degenerative diseases. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Characterization of a Flavoprotein Oxidase from Opium Poppy Catalyzing the Final Steps in Sanguinarine and Papaverine Biosynthesis*

    Science.gov (United States)

    Hagel, Jillian M.; Beaudoin, Guillaume A. W.; Fossati, Elena; Ekins, Andrew; Martin, Vincent J. J.; Facchini, Peter J.

    2012-01-01

    Benzylisoquinoline alkaloids are a diverse class of plant specialized metabolites that includes the analgesic morphine, the antimicrobials sanguinarine and berberine, and the vasodilator papaverine. The two-electron oxidation of dihydrosanguinarine catalyzed by dihydrobenzophenanthridine oxidase (DBOX) is the final step in sanguinarine biosynthesis. The formation of the fully conjugated ring system in sanguinarine is similar to the four-electron oxidations of (S)-canadine to berberine and (S)-tetrahydropapaverine to papaverine. We report the isolation and functional characterization of an opium poppy (Papaver somniferum) cDNA encoding DBOX, a flavoprotein oxidase with homology to (S)-tetrahydroprotoberberine oxidase and the berberine bridge enzyme. A query of translated opium poppy stem transcriptome databases using berberine bridge enzyme yielded several candidate genes, including an (S)-tetrahydroprotoberberine oxidase-like sequence selected for heterologous expression in Pichia pastoris. The recombinant enzyme preferentially catalyzed the oxidation of dihydrosanguinarine to sanguinarine but also converted (RS)-tetrahydropapaverine to papaverine and several protoberberine alkaloids to oxidized forms, including (RS)-canadine to berberine. The Km values of 201 and 146 μm for dihydrosanguinarine and the protoberberine alkaloid (S)-scoulerine, respectively, suggested high concentrations of these substrates in the plant. Virus-induced gene silencing to reduce DBOX transcript levels resulted in a corresponding reduction in sanguinarine, dihydrosanguinarine, and papaverine accumulation in opium poppy roots in support of DBOX as a multifunctional oxidative enzyme in BIA metabolism. PMID:23118227

  7. Characterization of a flavoprotein oxidase from opium poppy catalyzing the final steps in sanguinarine and papaverine biosynthesis.

    Science.gov (United States)

    Hagel, Jillian M; Beaudoin, Guillaume A W; Fossati, Elena; Ekins, Andrew; Martin, Vincent J J; Facchini, Peter J

    2012-12-14

    Benzylisoquinoline alkaloids are a diverse class of plant specialized metabolites that includes the analgesic morphine, the antimicrobials sanguinarine and berberine, and the vasodilator papaverine. The two-electron oxidation of dihydrosanguinarine catalyzed by dihydrobenzophenanthridine oxidase (DBOX) is the final step in sanguinarine biosynthesis. The formation of the fully conjugated ring system in sanguinarine is similar to the four-electron oxidations of (S)-canadine to berberine and (S)-tetrahydropapaverine to papaverine. We report the isolation and functional characterization of an opium poppy (Papaver somniferum) cDNA encoding DBOX, a flavoprotein oxidase with homology to (S)-tetrahydroprotoberberine oxidase and the berberine bridge enzyme. A query of translated opium poppy stem transcriptome databases using berberine bridge enzyme yielded several candidate genes, including an (S)-tetrahydroprotoberberine oxidase-like sequence selected for heterologous expression in Pichia pastoris. The recombinant enzyme preferentially catalyzed the oxidation of dihydrosanguinarine to sanguinarine but also converted (RS)-tetrahydropapaverine to papaverine and several protoberberine alkaloids to oxidized forms, including (RS)-canadine to berberine. The K(m) values of 201 and 146 μm for dihydrosanguinarine and the protoberberine alkaloid (S)-scoulerine, respectively, suggested high concentrations of these substrates in the plant. Virus-induced gene silencing to reduce DBOX transcript levels resulted in a corresponding reduction in sanguinarine, dihydrosanguinarine, and papaverine accumulation in opium poppy roots in support of DBOX as a multifunctional oxidative enzyme in BIA metabolism.

  8. Characterization of the cydAB-Encoded Cytochrome bd Oxidase from Mycobacterium smegmatis

    Science.gov (United States)

    Kana, Bavesh D.; Weinstein, Edward A.; Avarbock, David; Dawes, Stephanie S.; Rubin, Harvey; Mizrahi, Valerie

    2001-01-01

    The cydAB genes from Mycobacterium smegmatis have been cloned and characterized. The cydA and cydB genes encode the two subunits of a cytochrome bd oxidase belonging to the widely distributed family of quinol oxidases found in prokaryotes. The cydD and cydC genes located immediately downstream of cydB encode a putative ATP-binding cassette-type transporter. At room temperature, reduced minus oxidized difference spectra of membranes purified from wild-type M. smegmatis displayed spectral features that are characteristic of the γ-proteobacterial type cytochrome bd oxidase. Inactivation of cydA or cydB by insertion of a kanamycin resistance marker resulted in loss of d-heme absorbance at 631 nm. The d-heme could be restored by transformation of the M. smegmatis cyd mutants with a replicating plasmid carrying the highly homologous cydABDC gene cluster from Mycobacterium tuberculosis. Inactivation of cydA had no effect on the ability of M. smegmatis to exit from stationary phase at 37 or 42°C. The growth rate of the cydA mutant was tested under oxystatic conditions. Although no discernible growth defect was observed under moderately aerobic conditions (9.2 to 37.5 × 102 Pa of pO2 or 5 to 21% air saturation), the mutant displayed a significant growth disadvantage when cocultured with the wild type under extreme microaerophilia (0.8 to 1.7 × 102 Pa of pO2 or 0.5 to 1% air saturation). These observations were in accordance with the two- to threefold increase in cydAB gene expression observed upon reduction of the pO2 of the growth medium from 21 to 0.5% air saturation and with the concomitant increase in d-heme absorbance in spectra of membranes isolated from wild-type M. smegmatis cultured at 1% air saturation. Finally, the cydA mutant displayed a competitive growth disadvantage in the presence of the terminal oxidase inhibitor, cyanide, when cocultured with wild type at 21% air saturation in an oxystat. In conjunction with these findings, our results suggest that

  9. RhoA/ROCK downregulates FPR2-mediated NADPH oxidase activation in mouse bone marrow granulocytes.

    Science.gov (United States)

    Filina, Julia V; Gabdoulkhakova, Aida G; Safronova, Valentina G

    2014-10-01

    Polymorphonuclear neutrophils (PMNs) express the high and low affinity receptors to formylated peptides (mFPR1 and mFPR2 in mice, accordingly). RhoA/ROCK (Rho activated kinase) pathway is crucial for cell motility and oxidase activity regulated via FPRs. There are contradictory data on RhoA-mediated regulation of NADPH oxidase activity in phagocytes. We have shown divergent Rho GTPases signaling via mFPR1 and mFPR2 to NADPH oxidase in PMNs from inflammatory site. The present study was aimed to find out the role of RhoA/ROCK in the respiratory burst activated via mFPR1 and mFPR2 in the bone marrow PMNs. Different kinetics of RhoA activation were detected with 0.1μM fMLF and 1μM WKYMVM operating via mFPR1 and mFPR2, accordingly. RhoA was translocated in fMLF-activated cells towards the cell center and juxtamembrane space versus uniform allocation in the resting cells. Specific inhibition of RhoA by CT04, Rho inhibitor I, weakly depressed the respiratory burst induced via mFPR1, but significantly increased the one induced via mFPR2. Inhibition of ROCK, the main effector of RhoA, by Y27632 led to the same effect on the respiratory burst. Regulation of mFPR2-induced respiratory response by ROCK was impossible under the cytoskeleton disruption by cytochalasin D, whereas it persisted in the case of mFPR1 activation. Thus we suggest RhoA to be one of the regulatory and signal transduction components in the respiratory burst through FPRs in the mouse bone marrow PMNs. Both mFPR1 and mFPR2 binding with a ligand trigger the activation of RhoA. FPR1 signaling through RhoA/ROCK increases NADPH-oxidase activity. But in FPR2 action RhoA/ROCK together with cytoskeleton-linked systems down-regulates NADPH-oxidase. This mechanism could restrain the reactive oxygen species dependent damage of own tissues during the chemotaxis of PMNs and in the resting cells. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Increased xanthine oxidase during labour--implications for oxidative stress.

    Science.gov (United States)

    Many, A; Roberts, J M

    1997-11-01

    Xanthine dehydrogenase/oxidase (XDH/XO) produces uric acid. When in the oxidase form, this production is coupled with the generation of free radicals. Hypoxia-reperfusion enhances conversion of XDH to XO. Since the placenta is exposed to short periods of hypoxia reperfusion during labour, 17 placentae of pregnancy terminated by elective caesarean section and five placentae of pregnancies terminated by caesarean section during labour were examined for XDH/XO activity. It was found that XO activity was higher in the placentae of labouring women (P = 0.003), which suggests that labour enhances conversion of XDH to XO, facilitating free radical production.

  11. Two X-linked chronic granulomatous disease patients with unusual NADPH oxidase properties

    NARCIS (Netherlands)

    Wolach, Baruch; Broides, Arnon; Zeeli, Tal; Gavrieli, Ronit; de Boer, Martin; van Leeuwen, Karin; Levy, Jacov; Roos, Dirk

    2011-01-01

    Chronic granulomatous disease (CGD) is an immune deficiency syndrome caused by defects in the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, the enzyme that generates reactive oxygen species (ROS) in phagocytizing leukocytes. This study evaluates the NADPH oxidase capacity in two

  12. Catalytic aspects of a copper(II) complex: biological oxidase to ...

    Indian Academy of Sciences (India)

    BISWAJIT CHOWDHURY

    2017-10-03

    Oct 3, 2017 ... made with a Jasco model V-730 UV-Vis spectrophotometer. ..... Ligand-induced coordination changes ... Fet3 protein from yeast, a multinuclear copper oxidase ... of mutants of the multicopper oxidase Fet3p Biochem-.

  13. Rac1-NADPH oxidase signaling promotes CD36 activation under glucotoxic conditions in pancreatic beta cells.

    Science.gov (United States)

    Elumalai, Suma; Karunakaran, Udayakumar; Lee, In Kyu; Moon, Jun Sung; Won, Kyu Chang

    2017-04-01

    We recently reported that cluster determinant 36 (CD36), a fatty acid transporter, plays a pivotal role in glucotoxicity-induced β-cell dysfunction. However, little is known about how glucotoxicity influences CD36 expression. Emerging evidence suggests that the small GTPase Rac1 is involved in the pathogenesis of beta cell dysfunction in type 2 diabetes (T2D). The primary objective of the current study was to determine the role of Rac1 in CD36 activation and its impact on β-cell dysfunction in diabetes mellitus. To address this question, we subjected INS-1 cells and human beta cells (1.1B4) to high glucose conditions (30mM) in the presence or absence of Rac1 inhibition either by NSC23766 (Rac1 GTPase inhibitor) or small interfering RNA. High glucose exposure in INS-1 and human beta cells (1.1b4) resulted in the activation of Rac1 and induced cell apoptosis. Rac1 activation mediates NADPH oxidase (NOX) activation leading to elevated ROS production in both cells. Activation of the Rac1-NOX complex by high glucose levels enhanced CD36 expression in INS-1 and human 1.1b4 beta cell membrane fractions. The inhibition of Rac1 by NSC23766 inhibited NADPH oxidase activity and ROS generation induced by high glucose concentrations in INS-1 & human 1.1b4 beta cells. Inhibition of Rac1-NOX complex activation by NSC23766 significantly reduced CD36 expression in INS-1 and human 1.1b4 beta cell membrane fractions. In addition, Rac1 inhibition by NSC23766 significantly reduced high glucose-induced mitochondrial dysfunction. Furthermore, NADPH oxidase inhibition by VAS2870 also attenuated high glucose-induced ROS generation and cell apoptosis. These results suggest that Rac1-NADPH oxidase dependent CD36 expression contributes to high glucose-induced beta cell dysfunction and cell death. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Scanning tunneling microscopy studies of glucose oxidase on gold surface

    International Nuclear Information System (INIS)

    Losic, D.; Shapter, J.G.; Gooding, J.J.

    2002-01-01

    Full text: Three immobilization methods have been used for scanning tunneling microscopy (STM) studies of glucose oxidase (GOD) on gold. They are based on a) physical adsorption from solution, b) microcontact printing and c) covalent bonding onto self-assembled monolayers (SAM) of 3-mercaptopropionic acid (MPA). The STM images are used to provide information about the organization of individual GOD molecules and more densely packed monolayers of GOD on electrode surfaces, thus providing information of the role of interfacial structure on biosensor performance. The use of atomically flat gold substrates enables easy distinction of deposited enzyme features from the flat gold substrate. Microcontact printing is found to be a more reliable method than adsorption from solution for preparing individual GOD molecules on the gold surface STM images of printed samples reveal two different shapes of native GOD molecules. One is a butterfly shape with dimensions of 10 ± 1 nm x 6 ± 1 nm, assigned to the lying position of molecule while the second is an approximately spherical shape with dimensions of 6.5 ± 1 nm x 5 ± 1nm assigned to a standing position. Isolated clusters of 5 to 6 GOD molecules are also observed. With monolayer coverage, GOD molecules exhibit a tendency to organize themselves into a two dimensional array with adequate sample stability to obtain high-resolution STM images. Within these two-dimensional arrays are clearly seen repeating clusters of five to six enzyme molecules in a unit STM imaging of GOD monolayers covalently immobilized onto SAM (MPA) are considerably more difficult than when the enzyme is adsorbed directly onto the metal. Cluster structures are observed both high and low coverage despite the fact that native GOD is a negatively charged molecule. Copyright (2002) Australian Society for Electron Microscopy Inc

  15. Decoding NADPH oxidase 4 expression in human tumors

    Directory of Open Access Journals (Sweden)

    Jennifer L. Meitzler

    2017-10-01

    Full Text Available NADPH oxidase 4 (NOX4 is a redox active, membrane-associated protein that contributes to genomic instability, redox signaling, and radiation sensitivity in human cancers based on its capacity to generate H2O2 constitutively. Most studies of NOX4 in malignancy have focused on the evaluation of a small number of tumor cell lines and not on human tumor specimens themselves; furthermore, these studies have often employed immunological tools that have not been well characterized. To determine the prevalence of NOX4 expression across a broad range of solid tumors, we developed a novel monoclonal antibody that recognizes a specific extracellular region of the human NOX4 protein, and that does not cross-react with any of the other six members of the NOX gene family. Evaluation of 20 sets of epithelial tumors revealed, for the first time, high levels of NOX4 expression in carcinomas of the head and neck (15/19 patients, esophagus (12/18 patients, bladder (10/19 patients, ovary (6/17 patients, and prostate (7/19 patients, as well as malignant melanoma (7/15 patients when these tumors were compared to histologically-uninvolved specimens from the same organs. Detection of NOX4 protein upregulation by low levels of TGF-β1 demonstrated the sensitivity of this new probe; and immunofluorescence experiments found that high levels of endogenous NOX4 expression in ovarian cancer cells were only demonstrable associated with perinuclear membranes. These studies suggest that NOX4 expression is upregulated, compared to normal tissues, in a well-defined, and specific group of human carcinomas, and that its expression is localized on intracellular membranes in a fashion that could modulate oxidative DNA damage.

  16. Cytochrome cbb3 of Thioalkalivibrio is a Na+-pumping cytochrome oxidase

    NARCIS (Netherlands)

    Muntyan, M.S.; Cherepanov, D.A.; Malinen, A.M.; Bloch, D.A.; Sorokin, D.Y.; Severina, I.I.; Ivashina, T.V.; Lahti, R.; Muyzer, G.; Skulachev, V.P.

    2015-01-01

    Cytochrome c oxidases (Coxs) are the basic energy transducers in the respiratory chain of the majority of aerobic organisms. Coxs studied to date are redox-driven proton-pumping enzymes belonging to one of three subfamilies: A-, B-, and C-type oxidases. The C-type oxidases (cbb3 cytochromes), which

  17. Cyanobacterial Lactate Oxidases Serve as Essential Partners in N2 Fixation and Evolved into Photorespiratory Glycolate Oxidases in Plants[w

    Science.gov (United States)

    Hackenberg, Claudia; Kern, Ramona; Hüge, Jan; Stal, Lucas J.; Tsuji, Yoshinori; Kopka, Joachim; Shiraiwa, Yoshihiro; Bauwe, Hermann; Hagemann, Martin

    2011-01-01

    Glycolate oxidase (GOX) is an essential enzyme involved in photorespiratory metabolism in plants. In cyanobacteria and green algae, the corresponding reaction is catalyzed by glycolate dehydrogenases (GlcD). The genomes of N2-fixing cyanobacteria, such as Nostoc PCC 7120 and green algae, appear to harbor genes for both GlcD and GOX proteins. The GOX-like proteins from Nostoc (No-LOX) and from Chlamydomonas reinhardtii showed high l-lactate oxidase (LOX) and low GOX activities, whereas glycolate was the preferred substrate of the phylogenetically related At-GOX2 from Arabidopsis thaliana. Changing the active site of No-LOX to that of At-GOX2 by site-specific mutagenesis reversed the LOX/GOX activity ratio of No-LOX. Despite its low GOX activity, No-LOX overexpression decreased the accumulation of toxic glycolate in a cyanobacterial photorespiratory mutant and restored its ability to grow in air. A LOX-deficient Nostoc mutant grew normally in nitrate-containing medium but died under N2-fixing conditions. Cultivation under low oxygen rescued this lethal phenotype, indicating that N2 fixation was more sensitive to O2 in the Δlox Nostoc mutant than in the wild type. We propose that LOX primarily serves as an O2-scavenging enzyme to protect nitrogenase in extant N2-fixing cyanobacteria, whereas in plants it has evolved into GOX, responsible for glycolate oxidation during photorespiration. PMID:21828292

  18. Davallialactone reduces inflammation and repairs dentinogenesis on glucose oxidase-induced stress in dental pulp cells.

    Science.gov (United States)

    Lee, Young-Hee; Kim, Go-Eun; Song, Yong-Beom; Paudel, Usha; Lee, Nan-Hee; Yun, Bong-Sik; Yu, Mi-Kyung; Yi, Ho-Keun

    2013-11-01

    The chronic nature of diabetes mellitus (DM) raises the risk of oral complication diseases. In general, DM causes oxidative stress to organs. This study aimed to evaluate the cellular change of dental pulp cells against glucose oxidative stress by glucose oxidase with a high glucose state. The purpose of this study was to test the antioxidant character of davallialactone and to reduce the pathogenesis of dental pulp cells against glucose oxidative stress. The glucose oxidase with a high glucose concentration was tested for hydroxy peroxide (H2O2) production, cellular toxicity, reactive oxygen species (ROS) formation, induction of inflammatory molecules and disturbance of dentin mineralization in human dental pulp cells. The anti-oxidant effect of Davallilactone was investigated to restore dental pulp cells' vitality and dentin mineralization via reduction of H2O2 production, cellular toxicity, ROS formation and inflammatory molecules. The treatment of glucose oxidase with a high glucose concentration increased H2O2 production, cellular toxicity, and inflammatory molecules and disturbed dentin mineralization by reducing pulp cell activity. However, davallialactone reduced H2O2 production, cellular toxicity, ROS formation, inflammatory molecules, and dentin mineralization disturbances even with a long-term glucose oxidative stress state. The results of this study imply that the development of oral complications is related to the irreversible damage of dental pulp cells by DM-induced oxidative stress. Davallialactone, a natural antioxidant, may be useful to treat complicated oral disease, representing an improvement for pulp vital therapy. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  19. A preliminary neutron diffraction study of rasburicase, a recombinant urate oxidase enzyme, complexed with 8-azaxanthin

    Energy Technology Data Exchange (ETDEWEB)

    Budayova-Spano, Monika, E-mail: spano@embl-grenoble.fr [European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France); Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble (France); Bonneté, Françoise; Ferté, Natalie [Centre de Recherche en Matière Condensée et Nanosciences, Campus de Luminy, Case 913, 13288 Marseille (France); El Hajji, Mohamed [Sanofi-Aventis, 371 Rue du Professeur Blayac, 34184 Montpellier (France); Meilleur, Flora [Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble (France); Blakeley, Matthew Paul [European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France); Castro, Bertrand [Sanofi-Aventis, 371 Rue du Professeur Blayac, 34184 Montpellier (France); European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France)

    2006-03-01

    Neutron diffraction data of hydrogenated recombinant urate oxidase enzyme (Rasburicase), complexed with a purine-type inhibitor 8-azaxanthin, was collected to 2.1 Å resolution from a crystal grown in D{sub 2}O by careful control and optimization of crystallization conditions via knowledge of the phase diagram. Deuterium atoms were clearly seen in the neutron-scattering density map. Crystallization and preliminary neutron diffraction measurements of rasburicase, a recombinant urate oxidase enzyme expressed by a genetically modified Saccharomyces cerevisiae strain, complexed with a purine-type inhibitor (8-azaxanthin) are reported. Neutron Laue diffraction data were collected to 2.1 Å resolution using the LADI instrument from a crystal (grown in D{sub 2}O) with volume 1.8 mm{sup 3}. The aim of this neutron diffraction study is to determine the protonation states of the inhibitor and residues within the active site. This will lead to improved comprehension of the enzymatic mechanism of this important enzyme, which is used as a protein drug to reduce toxic uric acid accumulation during chemotherapy. This paper illustrates the high quality of the neutron diffraction data collected, which are suitable for high-resolution structural analysis. In comparison with other neutron protein crystallography studies to date in which a hydrogenated protein has been used, the volume of the crystal was relatively small and yet the data still extend to high resolution. Furthermore, urate oxidase has one of the largest primitive unit-cell volumes (space group I222, unit-cell parameters a = 80, b = 96, c = 106 Å) and molecular weights (135 kDa for the homotetramer) so far successfully studied with neutrons.

  20. Time-to-positivity, type of culture media and oxidase test performed on positive blood culture vials to predict Pseudomonas aeruginosa in patients with Gram-negative bacilli bacteraemia.

    Science.gov (United States)

    Cobos-Triguero, N; Zboromyrska, Y; Morata, L; Alejo, I; De La Calle, C; Vergara, A; Cardozo, C; Arcas, M P; Soriano, A; Marco, F; Mensa, J; Almela, M; Martínez, J A

    2017-02-01

    The aim of this study was to determine the usefulness of oxidase test and time-to-positivity (TTP) in aerobic and anaerobic blood culture vials to detect the presence of Pseudomonas aeruginosa in patients with Gram-negative bacilli (GNB) bacteraemia. TTP was recorded for each aerobic and anaerobic blood culture vial of monomicrobial bacteraemia due to GNB. Oxidase test was performed in a pellet of the centrifuged content of the positive blood culture. An algorithm was developed in order to perform the oxidase test efficiently taking into account TTP and type of vial. A total of 341 episodes of GNB bacteraemia were analysed. Sensitivity, specificity, positive predictive value and negative predictive value of the oxidase test performed on positive vials with GNB to predict P. aeruginosa were 95%, 99%, 91%, and 99%, respectively. When growth was first or exclusively detected in anaerobic vials, P. aeruginosa was never identified hence the performance of the oxidase test could be avoided. When growth was only or first detected in aerobic vials, a TTP≥8h predicted P. aeruginosa in 37% or cases (63 of 169), therefore oxidase test is highly recommended. Oxidase test performed onto positive blood culture vials previously selected by TTP and type of vials is an easy and inexpensive way to predict P. aeruginosa. In most cases, this can lead to optimization of treatment in less than 24 hours.

  1. Enhanced production of glucose oxidase from UVmutant of ...

    African Journals Online (AJOL)

    UV rays were used as mutagen in wild type strain of Aspergillus niger for enhanced production of glucose oxidase. After mutangenization and selection, mutant A. niger strains, resistant to 2-deoxy-Dglucose were obtained. The mutants showed 1.57 and 1.98 fold increase in activities of extra and intra cellular glucose ...

  2. Localization of Glucose Oxidase and Catalase Activities in Aspergillus niger

    NARCIS (Netherlands)

    Witteveen, Cor F.B.; Veenhuis, Marten; Visser, Jaap

    The subcellular localization of glucose oxidase (EC 1.1.3.4) in Aspergillus niger N400 (CBS 120.49) was investigated by (immuno)cytochemical methods. By these methods, the bulk of the enzyme was found to be localized in the cell wall. In addition, four different catalases (EC 1.11.1.6) were

  3. The glucose oxidase-peroxidase assay for glucose

    Science.gov (United States)

    The glucose oxidase-peroxidase assay for glucose has served as a very specific, sensitive, and repeatable assay for detection of glucose in biological samples. It has been used successfully for analysis of glucose in samples from blood and urine, to analysis of glucose released from starch or glycog...

  4. Nanoporous gold assembly of glucose oxidase for electrochemical biosensing

    DEFF Research Database (Denmark)

    Xiao, Xinxin; Ulstrup, Jens; Li, Hui

    2014-01-01

    Nanoporous gold (NPG) is composed of three-dimensional (3D) bicontinuous nanostructures with large surface area. Nano-channels inside NPG provide an ideal local environment for immobilization of enzyme molecules with expected stabilization of the protein molecules. In this work, glucose oxidase (...

  5. Gene cloning and characterization of NADH oxidase from ...

    African Journals Online (AJOL)

    The genome search of Thermococcus kodakarensis revealed three open reading frames, Tk0304, Tk1299 and Tk1392 annotated as nicotinamide adenine dinucleotide (NADH) oxidases. This study deals with cloning, and characterization of Tk0304. The gene, composed of 1320 nucleotides, encodes a protein of 439 ...

  6. Optimization of cholesterol oxidase production by Brevibacterium sp ...

    African Journals Online (AJOL)

    An ultrasound-assisted emulsification as a pretreatment for cholesterol oxidase production by submerge fermentation using Brevibacterium sp. in a batch system was studied. Medium improvement for the production employing response surface methodology (RSM) was optimized in this paper. The concentration of ...

  7. in Escherichia coli with native cholesterol oxidase expressed

    African Journals Online (AJOL)

    The structure and bio-activity of an endogenous cholesterol oxidase from Brevibacterium sp. was compared to the same enzyme exogenously expressed in Escherichia coli BL21 (DE3) with and without N- or C-terminal his-tags. The different proteins were purified with affinity and subtractive protocols. The specific activity of ...

  8. Cytokinin oxidase or dehydrogenase? Mechanism of cytokinin degradation in cereals

    DEFF Research Database (Denmark)

    Galuszka, P.; Frebort, I.; Sebela, M.

    2001-01-01

    An enzyme degrading cytokinins with isoprenoid side chain, previously named cytokinin oxidase, was purified to near homogeneity from wheat and barley grains. New techniques were developed for the enzyme activity assay and staining on native electrophoretic gels to identify the protein. The purifi...

  9. Effect of heat treatment on polyphenol oxidase and peroxidase ...

    African Journals Online (AJOL)

    Effect of heat treatment (55°C/20 min) on polyphenol oxidase (PPO) and peroxidase (POD) activities and total phenolic compounds was investigated in Algerian dates (Deglet Nour variety) at Tamar (fully ripe) stage and in dates stored for 5 months at ambient temperature and in cold storage (10°C). Results obtained ...

  10. Lysyl oxidases regulate fibrillar collagen remodelling in idiopathic pulmonary fibrosis

    NARCIS (Netherlands)

    Tjin, Gavin; White, Eric S; Faiz, Alen; Sicard, Delphine; Tschumperlin, Daniel J; Mahar, Annabelle; Kable, Eleanor P W; Burgess, Janette K

    2017-01-01

    Idiopathic pulmonary fibrosis (IPF) is a progressive scarring disease of the lung with feweffective therapeutic options. Structural remodelling of the extracellular matrix [i.e. collagen cross-linkingmediated by the lysyl oxidase (LO) family of enzymes (LOX, LOXL1-4)] might contribute to disease

  11. Novel thidiazuron-derived inhibitors of cytokinin oxidase/dehydrogenase

    Czech Academy of Sciences Publication Activity Database

    Nisler, Jaroslav; Kopečný, D.; Končitíková, R.; Zatloukal, Marek; Bazgier, Václav; Berka, K.; Zalabák, D.; Briozzo, P.; Strnad, Miroslav; Spíchal, Lukáš

    2016-01-01

    Roč. 92, 1-2 (2016), s. 235-248 ISSN 0167-4412 R&D Projects: GA MŠk(CZ) LO1204; GA ČR GA15-22322S Institutional support: RVO:61389030 Keywords : Cytokinin oxidase/dehydrogenase * Crystal structure * Molecular docking Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.356, year: 2016

  12. DNA damage and decrease of cellular oxidase activity in piglet ...

    African Journals Online (AJOL)

    DNA damage and decrease of cellular oxidase activity in piglet sertoli cells exposed to gossypol. Ming Zhang, Hui Yuan, Zuping He, Liyun Yuan, Jine Yi, Sijun Deng, Li Zhu, Chengzhi Guo, Yin Lu, Jing Wu, Lixin Wen, Qiang Wei, Liqun Xue ...

  13. Adenine nucleotide depletion from endothelial cells exposed to xanthine oxidase

    International Nuclear Information System (INIS)

    Aalto, T.K.; Raivio, K.O.

    1990-01-01

    Hypoxia causes breakdown of cellular nucleotides, accumulation of hypoxanthine (HX), and conversion of xanthine dehydrogenase into xanthine oxidase (XO). Upon reoxygenation, the HX-XO reaction generates free radicals, one potential mechanism of tissue damage. Because endothelial cells contain XO and are exposed to circulating HX, they are a likely target for damage. We studied the effect of XO and/or HX at physiologically relevant concentrations on nucleotide metabolism of cultured endothelial cells from human umbilical veins. Cells were labeled with [14C]adenine and incubated for up to 6 h with HX, XO, or both, in the absence or presence of serum. Adenine nucleotides from cell extracts and nucleotide breakdown products (HX, xanthine, and urate) from the medium were separated and counted. HX alone had no effect. XO (80 mU/ml) alone caused a 70% (no serum) or 40% (with serum) fall in adenine nucleotides and an equivalent increase of xanthine and urate. The combination of HX and XO caused a 90% (no serum) or 70% (with serum) decrease in nucleotides, decrease in energy charge, and detachment of cells from the culture plate. Nucleotide depletion was not accounted for by proteolytic activity in the XO preparation. Albumin was only half as effective as serum in preventing nucleotide loss. Thus exogenous XO, in the presence of endogenous HX, triggers adenine nucleotide catabolism, but endogenous XO activity is too low to influence nucleotide levels even at high exogenous HX concentrations. Serum limits the catabolic effect of XO and thus protects cells from free radical damage

  14. COI (cytochrome oxidase-I) sequence based studies of Carangid fishes from Kakinada coast, India.

    Science.gov (United States)

    Persis, M; Chandra Sekhar Reddy, A; Rao, L M; Khedkar, G D; Ravinder, K; Nasruddin, K

    2009-09-01

    Mitochondrial DNA, cytochrome oxidase-1 gene sequences were analyzed for species identification and phylogenetic relationship among the very high food value and commercially important Indian carangid fish species. Sequence analysis of COI gene very clearly indicated that all the 28 fish species fell into five distinct groups, which are genetically distant from each other and exhibited identical phylogenetic reservation. All the COI gene sequences from 28 fishes provide sufficient phylogenetic information and evolutionary relationship to distinguish the carangid species unambiguously. This study proves the utility of mtDNA COI gene sequence based approach in identifying fish species at a faster pace.

  15. Renal denervation attenuates NADPH oxidase-mediated oxidative stress and hypertension in rats with hydronephrosis

    DEFF Research Database (Denmark)

    Peleli, Maria; Al-Mashhadi, Ammar; Yang, Ting

    2016-01-01

    Hydronephrosis is associated with development of salt-sensitive hypertension. Studies suggest that increased sympathetic nerve activity (SNA) and oxidative stress play important roles in renovascular hypertension. This study aimed to investigate the link between renal SNA and NADPH oxidase (NOX......) regulation in the development of hypertension in rats with hydronephrosis. Hydronephrosis was induced by partial unilateral ureteral obstruction (PUUO) in young rats. Sham surgery or renal denervation was performed at the same time. Blood pressure was measured during normal, high and low salt diets. Renal...

  16. Inactivation of 1-aminocyclopropane-1-carboxylate oxidase involves oxidative modifications.

    Science.gov (United States)

    Barlow, J N; Zhang, Z; John, P; Baldwin, J E; Schofield, C J

    1997-03-25

    1-Aminocyclopropane-1-carboxylate (ACC) oxidase catalyzes the final step in the biosynthesis of the plant signaling molecule ethylene. It is a member of the ferrous iron dependent family of oxidases and dioxygenases and is unusual in that it displays a very short half-life under catalytic conditions, typically less than 20 min, and a requirement for CO2 as an activator. The rates of inactivation of purified, recombinant ACC oxidase from tomato under various combinations of substrates and cofactors were measured. Inactivation was relatively slow in the presence of buffer alone (t1/2 > 1 h), but fast in the presence of ferrous iron and ascorbate (t1/2 approximately 10 min). The rate of iron/ascorbate-mediated inactivation was increased by the addition of ACC, unaffected by the addition of CO2 at saturation (supplied as bicarbonate) but decreased by the addition of catalase or ACC + CO2 at saturation (supplied as bicarbonate). Iron/ascorbate-mediated inactivation was accompanied by partial proteolysis as observed by SDS-PAGE analysis. The fragmentation pattern was altered when ACC was also included, suggesting that ACC can bind to ACC oxidase in the absence of bicarbonate. N-terminal sequencing of fragments resulted in identification of an internal cleavage site which we propose is proximate to active-site bound iron. Thus, ACC oxidase inactivates via relatively slow partial unfolding of the catalytically active conformation, oxidative damage mediated via hydrogen peroxide which is catalase protectable and oxidative damage to the active site which results in partial proteolysis and is not catalase protectable.

  17. Expression Studies of Gibberellin Oxidases in Developing Pumpkin Seeds1

    Science.gov (United States)

    Frisse, Andrea; Pimenta, Maria João; Lange, Theo

    2003-01-01

    Two cDNA clones, 3-ox and 2-ox, have been isolated from developing pumpkin (Cucurbita maxima) embryos that show significant amino acid homology to gibberellin (GA) 3-oxidases and 2-oxidases, respectively. Recombinant fusion protein of clone 3-ox converted GA12-aldehyde, GA12, GA15, GA24, GA25, and GA9 to GA14-aldehyde, GA14, GA37, GA36, GA13, and GA4, respectively. Recombinant 2-ox protein oxidized GA9, GA4, and GA1 to GA51, GA34, and GA8, respectively. Previously cloned GA 7-oxidase revealed additional 3β-hydroxylation activity of GA12. Transcripts of this gene were identified in endosperm and embryo of the developing seed by quantitative reverse transcriptase-polymerase chain reaction and localized in protoderm, root apical meristem, and quiescent center by in situ hybridization. mRNA of the previously cloned GA 20-oxidase from pumpkin seeds was localized in endosperm and in tissues of protoderm, ground meristem, and cotyledons of the embryo. However, transcripts of the recently cloned GA 20-oxidase from pumpkin seedlings were found all over the embryo, and in tissues of the inner seed coat at the micropylar end. Previously cloned GA 2β,3β-hydroxylase mRNA molecules were specifically identified in endosperm tissue. Finally, mRNA molecules of the 3-ox and 2-ox genes were found in the embryo only. 3-ox transcripts were localized in tissues of cotyledons, protoderm, and inner cell layers of the root apical meristem, and 2-ox transcripts were found in all tissues of the embryo except the root tips. These results indicate tissue-specific GA-biosynthetic pathways operating within the developing seed. PMID:12644672

  18. Distinguishing the Roles of Thylakoid Respiratory Terminal Oxidases in the Cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Ermakova, Maria; Huokko, Tuomas; Richaud, Pierre; Bersanini, Luca; Howe, Christopher J; Lea-Smith, David J; Peltier, Gilles; Allahverdiyeva, Yagut

    2016-06-01

    Various oxygen-utilizing electron sinks, including the soluble flavodiiron proteins (Flv1/3), and the membrane-localized respiratory terminal oxidases (RTOs), cytochrome c oxidase (Cox) and cytochrome bd quinol oxidase (Cyd), are present in the photosynthetic electron transfer chain of Synechocystis sp. PCC 6803. However, the role of individual RTOs and their relative importance compared with other electron sinks are poorly understood, particularly under light. Via membrane inlet mass spectrometry gas exchange, chlorophyll a fluorescence, P700 analysis, and inhibitor treatment of the wild type and various mutants deficient in RTOs, Flv1/3, and photosystem I, we investigated the contribution of these complexes to the alleviation of excess electrons in the photosynthetic chain. To our knowledge, for the first time, we demonstrated the activity of Cyd in oxygen uptake under light, although it was detected only upon inhibition of electron transfer at the cytochrome b6f site and in ∆flv1/3 under fluctuating light conditions, where linear electron transfer was drastically inhibited due to impaired photosystem I activity. Cox is mostly responsible for dark respiration and competes with P700 for electrons under high light. Only the ∆cox/cyd double mutant, but not single mutants, demonstrated a highly reduced plastoquinone pool in darkness and impaired gross oxygen evolution under light, indicating that thylakoid-based RTOs are able to compensate partially for each other. Thus, both electron sinks contribute to the alleviation of excess electrons under illumination: RTOs continue to function under light, operating on slower time ranges and on a limited scale, whereas Flv1/3 responds rapidly as a light-induced component and has greater capacity. © 2016 American Society of Plant Biologists. All Rights Reserved.

  19. Mitochondrial terminal alternative oxidase and its enhancement by thermal stress in the coral symbiont Symbiodinium

    Science.gov (United States)

    Oakley, Clinton A.; Hopkinson, Brian M.; Schmidt, Gregory W.

    2014-06-01

    A terminal electron acceptor alternative to mitochondrial cytochrome c oxidase (COX), mitochondrial alternative oxidase (AOX), is ubiquitous in higher plants and represented in nearly every algal taxon but is poorly documented in dinoflagellates. AOX competes for electrons with the conventional COX and has been hypothesized to function as a means of reducing oxidative stress in mitochondria, as well as a potential mechanism for ameliorating thermal and other physiological stressors. Here, the presence of an active AOX in cultured Symbiodinium was assayed by the response of oxygen consumption to the AOX inhibitor salicylhydroxamic acid (SHAM) and the COX inhibitor cyanide (CN). CN-insensitive, SHAM-sensitive oxygen consumption was found to account for a large portion (26 %) of Symbiodinium dark respiration and is consistent with high levels of AOX activity. This experimental evidence of the existence of a previously unreported terminal oxidase was further corroborated by analysis of publicly available Symbiodinium transcriptome data. The potential for enhanced AOX expression to play a compensatory role in mediating thermal stress was supported by inhibitor assays of cultured Symbiodinium at low (18 °C), moderate (26 °C), and high (32 °C) temperature conditions. Maximum capacity of the putative AOX pathway as a proportion of total dark oxygen consumption was found to increase from 26 % at 26 °C to 45 % and 53 % at 18 °C and 32 °C, respectively, when cells were acclimated to the treatment temperatures. Cells assayed at 18 and 32 °C without acclimation exhibited either the same or lower AOX capacity as controls, suggesting that the AOX protein is upregulated under temperature stress. The physiological implications for the presence of AOX in the coral/algal symbiosis and its potential role in response to many forms of biotic and abiotic stress, particularly oxidative stress, are discussed.

  20. Absorption of enzymatically active 125I-labeled bovine milk xanthine oxidase fed to rabbits

    International Nuclear Information System (INIS)

    Rzucidlo, S.J.; Zikakis, J.P.

    1990-01-01

    Rabbits fed a regular laboratory diet supplemented with a high-fat milk containing xanthine oxidase (XO) were studied to determine the presence of active XO in the blood. A pilot feeding study, where rabbits consumed a high-fat diet containing xanthine oxidase, showed a correlation between dairy food consumption and XO activity in the blood. Antibody to dietary XO was also found. In a second study, rabbits were fed ad libitum the high-fat milk and blood serum samples were tested weekly for XO activity. No elevation in serum XO activity was found. A third study showed that serum XO activity was increased when rabbits were force fed the high-fat milk. The final study consisted of force feeding 125 I-labeled XO to one rabbit to ascertain whether the observed increase in serum XO was due to dietary or endogenous XO. Isoelectric focusing of sera collected from the test rabbit strongly suggested that at least a portion of the serum XO contained the radioactive label. This is the first direct evidence showing the uptake of dietary active XO from the gut

  1. Cyanobacterial lactate oxidases serve as essential partners in N2-fixation and evolved into photorespiratory glycolate oxidases in plants.

    NARCIS (Netherlands)

    Hackenberg, C.; Kern, R.; Hüge, J; Stal, L.J.; Tsuji, Y.; Kopka, J.; Shiraiwa, Y.; Bauwe, H.; Hagemann, M.

    2011-01-01

    Glycolate oxidase (GOX) is an essential enzyme involved in photorespiratory metabolism in plants. In cyanobacteria and green algae, the corresponding reaction is catalyzed by glycolate dehydrogenases (GlcD). The genomes of N2-fixing cyanobacteria, such as Nostoc PCC 7120 and green algae, appear to

  2. Cyanobacterial lactate oxidases serve as essential partners of N2-fixation and evolved to photorespiratory glycolate oxidases in plants

    NARCIS (Netherlands)

    Hackenberg, C.; Kern, R.; Hüge, J.; Stal, L.J.; Tsuji, Y.; Kopka, J.; Shiraiwa, Y.; Bauwe, H.; Hagemann, M.

    2011-01-01

    Glycolate oxidase (GOX) is an essential enzyme involved in photorespiratory metabolism in plants. In cyanobacteria and green algae, the corresponding reaction is catalyzed by glycolate dehydrogenases (GlcD). The genomes of N2-fixing cyanobacteria, such as Nostoc PCC 7120 and green algae, appear to

  3. Study on dioxygen reduction by mutational modifications of the hydrogen bond network leading from bulk water to the trinuclear copper center in bilirubin oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Morishita, Hirotoshi; Kurita, Daisuke; Kataoka, Kunishige; Sakurai, Takeshi, E-mail: tsakurai@se.kanazawa-u.ac.jp

    2014-07-18

    Highlights: • Proton transport pathway in bilirubin oxidase was mutated. • Two intermediates in the dioxygen reduction steps were trapped and characterized. • A specific glutamate for dioxygen reduction by multicopper oxidases was identified. - Abstract: The hydrogen bond network leading from bulk water to the trinuclear copper center in bilirubin oxidase is constructed with Glu463 and water molecules to transport protons for the four-electron reduction of dioxygen. Substitutions of Glu463 with Gln or Ala were attributed to virtually complete loss or significant reduction in enzymatic activities due to an inhibition of the proton transfer steps to dioxygen. The single turnover reaction of the Glu463Gln mutant afforded the highly magnetically interacted intermediate II (native intermediate) with a broad g = 1.96 electron paramagnetic resonance signal detectable at cryogenic temperatures. Reactions of the double mutants, Cys457Ser/Glu463Gln and Cys457Ser/Glu463Ala afforded the intermediate I (peroxide intermediate) because the type I copper center to donate the fourth electron to dioxygen was vacant in addition to the interference of proton transport due to the mutation at Glu463. The intermediate I gave no electron paramagnetic resonance signal, but the type II copper signal became detectable with the decay of the intermediate I. Structural and functional similarities between multicopper oxidases are discussed based on the present mutation at Glu463 in bilirubin oxidase.

  4. Study on dioxygen reduction by mutational modifications of the hydrogen bond network leading from bulk water to the trinuclear copper center in bilirubin oxidase

    International Nuclear Information System (INIS)

    Morishita, Hirotoshi; Kurita, Daisuke; Kataoka, Kunishige; Sakurai, Takeshi

    2014-01-01

    Highlights: • Proton transport pathway in bilirubin oxidase was mutated. • Two intermediates in the dioxygen reduction steps were trapped and characterized. • A specific glutamate for dioxygen reduction by multicopper oxidases was identified. - Abstract: The hydrogen bond network leading from bulk water to the trinuclear copper center in bilirubin oxidase is constructed with Glu463 and water molecules to transport protons for the four-electron reduction of dioxygen. Substitutions of Glu463 with Gln or Ala were attributed to virtually complete loss or significant reduction in enzymatic activities due to an inhibition of the proton transfer steps to dioxygen. The single turnover reaction of the Glu463Gln mutant afforded the highly magnetically interacted intermediate II (native intermediate) with a broad g = 1.96 electron paramagnetic resonance signal detectable at cryogenic temperatures. Reactions of the double mutants, Cys457Ser/Glu463Gln and Cys457Ser/Glu463Ala afforded the intermediate I (peroxide intermediate) because the type I copper center to donate the fourth electron to dioxygen was vacant in addition to the interference of proton transport due to the mutation at Glu463. The intermediate I gave no electron paramagnetic resonance signal, but the type II copper signal became detectable with the decay of the intermediate I. Structural and functional similarities between multicopper oxidases are discussed based on the present mutation at Glu463 in bilirubin oxidase

  5. Glucose oxidase probe as a surface-enhanced Raman scattering sensor for glucose.

    Science.gov (United States)

    Qi, Guohua; Wang, Yi; Zhang, Biying; Sun, Dan; Fu, Cuicui; Xu, Weiqing; Xu, Shuping

    2016-10-01

    Glucose oxidase (GOx) possessing a Raman-active chromophore (flavin adenine dinucleotide) is used as a signal reporter for constructing a highly specific "turn off" surface-enhanced Raman scattering (SERS) sensor for glucose. This sensing chip is made by the electrostatic assembly of GOx over silver nanoparticle (Ag NP)-functionalized SERS substrate through a positively charged polyelectrolyte linker under the pH of 6.86. To trace glucose in blood serum, owing to the reduced pH value caused by the production of gluconic acid in the GOx-catalyzed oxidation reaction, the bonding force between GOx and polyelectrolyte weakens, making GOx drop off from the sensing chip. As a result, the SERS intensity of GOx on the chip decreases along with the concentration of glucose. This glucose SERS sensor exhibits excellent selectivity based on the specific GOx/glucose catalysis reaction and high sensitivity to 1.0 μM. The linear sensing range is 2.0-14.0 mM, which also meets the requirement on the working range of the human blood glucose detection. Using GOx as a probe shows superiority over other organic probes because GOx almost has no toxicity to the biological system. This sensing mechanism can be applied for intracellular in vivo SERS monitoring of glucose in the future. Graphical abstract Glucose oxidase is used as a Raman signal reporter for constructing a highly specific glucose surface-enhanced Raman scattering (SERS) sensor.

  6. Screening of Bothrops snake venoms for L-amino acid oxidase activity

    Energy Technology Data Exchange (ETDEWEB)

    Pessati, M.L.; Fontana, J.D.; Guimaraes, M.F. [Federal Univ. of Parana, Curitiba (Brazil)

    1995-12-31

    Toxins, enzymes, and biologically active peptides are the main components of snake venoms from the genus Bothrops. Following the venom inoculation, the local effects are hemorrhage, edema, and myonecrosis. Nineteen different species of Brazilian Bothrops were screened for protein content and L-amino acid oxidase activity. B. cotiara, formerly found in the South of Brazil, is now threatened with extinction. Its venom contains a highly hemorrhagic fraction and, as expected from the deep yellow color of the corresponding lyophilized powder, a high L-amino acid oxidase (LAO) activity was also characterized. Flavin adenine dinucleotide (FAD) is its associate coenzyme. B. cotiara venom LAO catalyzed the oxidative deamination of several L-amino acids, and the best substrates were methionine, leucine, tryptophan, and phenylalanine, hence, its potential application for the use in biosensors for aspartame determination and for the removal of amino acids from plasma. High levels for LAO were also found in other species than B. cotiara. In addition, the technique of isoelectric focusing (IEF) was employed as a powerful tool to study the iso- or multi-enzyme distribution for LAO activity in the B. cotiara snake venom.

  7. Immobilization of Glucose Oxidase on Modified-Carbon-Paste-Electrodes for Microfuel Cell

    Directory of Open Access Journals (Sweden)

    Laksmi Ambarsari

    2016-03-01

    Full Text Available Glucose oxidase (GOx is being developed for many applications such as an implantable fuel cell, due to its attractive property of operating under physiological conditions. This study reports the functional immobilization of glucose oxidase onto polyaniline-nanofiber-modified-carbon-paste-electrodes (GOx/MCPE as bioanodes in fuel cell applications. In particular, GOx is immobilized onto the electrode surface via a linker molecule (glutaraldehyde. Polyaniline, synthesized by the interfacial polymerization method, produces a morphological form of nanofibers (100-120 nm which have good conductivity. The performance of the polyaniline-modified-carbon-paste-electrode (MCPE was better than the carbon- paste-electrode (CPE alone. The optimal pH and temperature of the GOx/MCPE were 4.5 (in 100 mM acetate buffer and 65 °C, respectively. The GOx/MCPE exhibit high catalytic performances (activation energy 16.4 kJ mol-1, have a high affinity for glucose (Km value 37.79 µM and can have a maximum current (Imax of 3.95 mA. The sensitivity of the bioelectrode also was high at 57.79 mA mM-1 cm-2.

  8. Association of molecular markers with polyphenol oxidase activity in selected wheat genotypes

    International Nuclear Information System (INIS)

    Abbas, Z.; Javad, B.; Majeed, N.; Naqvi, S.

    2016-01-01

    Wheat (Triticum aestivum L.), a major staple food for the people of Pakistan and other Asian countries, is used as bread, chapatti, porridge, noodles and many other. It is established that color quality of wheat products depend on chemical and enzymatic factors especially the polyphenol oxidases (PPOs). These are copper containing enzymes which induce browning in wheat-based products. Various procedures for determining PPO activity available and differences in PPO activity among wheat genotypes have been documented. In present study, an attempt was made to establish the association of molecular markers with polyphenol oxidase activity in wheat genotypes having very high or very low PPO activities. Twelve pairs of markers were used out of which only three primer pairs viz. PPO43, PPO30 and WP2-2 yielded specific pattern discriminating high and low PPO genotypes. Cluster analysis for all 12 markers revealed that all the low PPO lline share the same sub cluster, but high PPO lines were dispersed in different clusters. (author)

  9. Neutrophils to the ROScue: Mechanisms of NADPH Oxidase Activation and Bacterial Resistance

    Directory of Open Access Journals (Sweden)

    Giang T. Nguyen

    2017-08-01

    Full Text Available Reactive oxygen species (ROS generated by NADPH oxidase play an important role in antimicrobial host defense and inflammation. Their deficiency in humans results in recurrent and severe bacterial infections, while their unregulated release leads to pathology from excessive inflammation. The release of high concentrations of ROS aids in clearance of invading bacteria. Localization of ROS release to phagosomes containing pathogens limits tissue damage. Host immune cells, like neutrophils, also known as PMNs, will release large amounts of ROS at the site of infection following the activation of surface receptors. The binding of ligands to G-protein-coupled receptors (GPCRs, toll-like receptors, and cytokine receptors can prime PMNs for a more robust response if additional signals are encountered. Meanwhile, activation of Fc and integrin directly induces high levels of ROS production. Additionally, GPCRs that bind to the bacterial-peptide analog fMLP, a neutrophil chemoattractant, can both prime cells and trigger low levels of ROS production. Engagement of these receptors initiates intracellular signaling pathways, resulting in activation of downstream effector proteins, assembly of the NADPH oxidase complex, and ultimately, the production of ROS by this complex. Within PMNs, ROS released by the NADPH oxidase complex can activate granular proteases and induce the formation of neutrophil extracellular traps (NETs. Additionally, ROS can cross the membranes of bacterial pathogens and damage their nucleic acids, proteins, and cell membranes. Consequently, in order to establish infections, bacterial pathogens employ various strategies to prevent restriction by PMN-derived ROS or downstream consequences of ROS production. Some pathogens are able to directly prevent the oxidative burst of phagocytes using secreted effector proteins or toxins that interfere with translocation of the NADPH oxidase complex or signaling pathways needed for its activation

  10. Heterologous expression of the Crassostrea gigas (Pacific oyster) alternative oxidase in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Robertson, Aaron; Schaltz, Kyle; Neimanis, Karina; Staples, James F; McDonald, Allison E

    2016-10-01

    Alternative oxidase (AOX) is a terminal oxidase within the inner mitochondrial membrane (IMM) present in many organisms where it functions in the electron transport system (ETS). AOX directly accepts electrons from ubiquinol and is therefore capable of bypassing ETS Complexes III and IV. The human genome does not contain a gene coding for AOX, so AOX expression has been suggested as a gene therapy for a range of human mitochondrial diseases caused by genetic mutations that render Complex III and/or IV dysfunctional. An effective means of screening mutations amenable to AOX treatment remains to be devised. We have generated such a tool by heterologously expressing AOX from the Pacific oyster (Crassostrea gigas) in the yeast Saccharomyces cerevisiae under the control of a galactose promoter. Our results show that this animal AOX is monomeric and is correctly targeted to yeast mitochondria. Moreover, when expressed in yeast, Pacific oyster AOX is a functional quinol oxidase, conferring cyanide-resistant growth and myxothiazol-resistant oxygen consumption to yeast cells and isolated mitochondria. This system represents a high-throughput screening tool for determining which Complex III and IV genetic mutations in yeast will be amenable to AOX gene therapy. As many human genes are orthologous to those found in yeast, our invention represents an efficient and cost-effective way to evaluate viable research avenues. In addition, this system provides the opportunity to learn more about the localization, structure, and regulation of AOXs from animals that are not easily reared or manipulated in the lab.

  11. Proton translocation stoichiometry of cytochrome oxidase: use of a fast-responding oxygen electrode.

    Science.gov (United States)

    Reynafarje, B; Alexandre, A; Davies, P; Lehninger, A L

    1982-01-01

    The mechanistic stoichiometry of vectorial H+ ejection coupled to electron transport from added ferrocytochrome c to oxygen by the cytochrome oxidase (EC 1.9.3.1) of rat liver mitoplasts was determined from measurements of the initial rates of electron flow and H+ ejection in the presence of K+ (with valinomycin). Three different methods of measuring electron flow were used: (a) dual-wavelength spectrophotometry of ferrocytochrome c oxidation, (b) uptake of scalar H+ for the reduction of O2 in the presence of a protonophore, and (c) a fast-responding membraneless oxygen electrode. The reliability of the rate measurements was first established against the known stoichiometry of the scalar reaction of cytochrome oxidase (2ferrocytochrome c + 2H+ + 1/2O2 leads to 2ferricytochrome c + H2O) in the presence of excess protonophore. With all three methods the directly observed vectorial H+/O ejection ratios in the presence of K+ + valinomycin significantly exceeded 3.0. However, because the rate of backflow of the ejected H+ into the mitoplasts is very high and increases with the increasing delta pH generated across the membrane, there is a very rapid decline in the observed H+/O ratio from the beginning of the reaction. Kinetic analysis of ferrocytochrome c oxidation by the mitoplasts, carried out with a fast-responding membraneless oxygen electrode, showed the reaction to be first order in O2 and allowed accurate extrapolation of the rates of O2 uptake and H+ ejection to zero time. At this point, at which there is zero delta pH across the membrane, the H+/O ejection ratio of the cytochrome oxidase reaction, obtained from the rates at zero time, is close to 4.0. PMID:6296824

  12. Identification and characterization of an antennae-specific aldehyde oxidase from the navel orangeworm.

    Directory of Open Access Journals (Sweden)

    Young-Moo Choo

    Full Text Available Antennae-specific odorant-degrading enzymes (ODEs are postulated to inactivate odorant molecules after they convey their signal. Different classes of insect ODEs are specific to esters, alcohols, and aldehydes--the major functional groups of female-produced, hydrophobic sex pheromones from moth species. Esterases that rapidly inactive acetate and other esters have been well-studied, but less is known about aldehyde oxidases (AOXs. Here we report cloning of an aldehyde oxidase, AtraAOX2, from the antennae of the navel orangeworm (NOW, Amyelois transitella, and the first activity characterization of a recombinant insect AOX. AtraAOX2 gene spans 3,813 bp and encodes a protein with 1,270 amino acid residues. AtraAOX2 cDNA was expressed in baculovirus-infected insect Sf21 cells as a ≈280 kDa homodimer with 140 kDa subunits. Recombinant AtraAOX2 degraded Z11Z13-16Ald and plant volatile aldehydes as substrates. However, as expected for aldehyde oxidases, recombinant AtraAOX2 did not show specificity for Z11Z13-16Ald, the main constituent of the sex pheromone, but showed high activity for plant volatile aldehydes. Our data suggest AtraAOX2 might be involved in degradation of a diversity of aldehydes including sex pheromones, plant-derived semiochemicals, and chemical cues for oviposition sites. Additionally, AtraAOX2 could protect the insect's olfactory system from xenobiotics, including pesticides that might reach the sensillar lymph surrounding the olfactory receptor neurons.

  13. Low-temperature kinetic measurements of microsecond freeze-hyperquench (MHQ) cytochrome oxidase monitored by UV-visible spectroscopy with a newly designed cuvette.

    Science.gov (United States)

    Wiertz, F G M; de Vries, S

    2006-02-01

    A special cuvette was designed to measure optical changes of MHQ (microsecond freeze-hyperquench) powder samples at temperatures below approx. 250 K. Reduced cytochrome c oxidase from Paracoccus denitrificans was reacted with O(2) for 100 micros, frozen as a powder and transferred to the cuvette. Subsequently, cytochrome oxidase was allowed to react further following stepwise increments of the temperature from 100 K up to 250 K while recording spectra between 300 and 700 nm. The temperature was raised only when no further changes in the spectra could be detected. The experiment yielded spectra of the A, P(M), F and O intermediate states. This demonstrated that the catalytic cycle of cytochrome oxidase at low temperature is similar to that at room temperature and so verifies the suitability of this method for the study of enzymes with high catalytic-centre activity.

  14. Biofilm Inhibition by Novel Natural Product- and Biocide-Containing Coatings Using High-Throughput Screening

    Directory of Open Access Journals (Sweden)

    Maria Salta

    2018-05-01

    Full Text Available The use of natural products (NPs as possible alternative biocidal compounds for use in antifouling coatings has been the focus of research over the past decades. Despite the importance of this field, the efficacy of a given NP against biofilm (mainly bacteria and diatoms formation is tested with the NP being in solution, while almost no studies test the effect of an NP once incorporated into a coating system. The development of a novel bioassay to assess the activity of NP-containing and biocide-containing coatings against marine biofilm formation has been achieved using a high-throughput microplate reader and highly sensitive confocal laser scanning microscopy (CLSM, as well as nucleic acid staining. Juglone, an isolated NP that has previously shown efficacy against bacterial attachment, was incorporated into a simple coating matrix. Biofilm formation over 48 h was assessed and compared against coatings containing the NP and the commonly used booster biocide, cuprous oxide. Leaching of the NP from the coating was quantified at two time points, 24 h and 48 h, showing evidence of both juglone and cuprous oxide being released. Results from the microplate reader showed that the NP coatings exhibited antifouling efficacy, significantly inhibiting biofilm formation when compared to the control coatings, while NP coatings and the cuprous oxide coatings performed equally well. CLSM results and COMSTAT analysis on biofilm 3D morphology showed comparable results when the NP coatings were tested against the controls, with higher biofilm biovolume and maximum thickness being found on the controls. This new method proved to be repeatable and insightful and we believe it is applicable in antifouling and other numerous applications where interactions between biofilm formation and surfaces is of interest.

  15. The Effects of Polyphenol Oxidase and Cycloheximide on the Early Stage of Browning in Phalaenopsis Explants

    Directory of Open Access Journals (Sweden)

    Xu Chuanjun

    2015-11-01

    Full Text Available Explant browning is one of the major problems in the tissue culture process, and polyphenol oxidase (PPO, is the major proteases involved in plant tissue browning. We investigated the effects of polyphenol oxidase on the early stage of browning in explants of the orchid Phalaenopsis. Our results show that PPO activity was significantly higher in explants cultured for 3 d than in the 0 h control. The levels of PPO transcripts and PPO protein were significantly higher in explants cultured for 6 h compared to the 0 h control; these high expression levels were maintained over increasing cultivation time. Cycloheximide (CHX treatment reduced PPO transcript levels, PPO protein levels, and PPO enzyme activity. High levels of PPO mRNA and PPO protein were detected in the cytoplasm and vascular bundles of Phalaenopsis explants cultured for 6 h compared to explants cultured for 0 h, 24 h, and 3 d. CHX treatment did not significantly affect the distribution of PPO mRNA and PPO protein in explant tissues, but their levels were significantly lower than those of the untreated control.

  16. Identification and characterization of aldehyde oxidases (AOXs) in the cotton bollworm

    Science.gov (United States)

    Xu, Wei; Liao, Yalin

    2017-12-01

    Aldehyde oxidases (AOXs) are a family of metabolic enzymes that oxidize aldehydes into carboxylic acids; therefore, they play critical roles in detoxification and degradation of chemicals. By using transcriptomic and genomic approaches, we successfully identified six putative AOX genes (HarmAOX1-6) from cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). In silico expression profile, reverse transcription (RT)-PCR, and quantitative PCR (qPCR) analyses showed that HarmAOX1 is highly expressed in adult antennae, tarsi, and larval mouthparts, so they may play an important role in degrading plant-derived compounds. HarmAOX2 is highly and specifically expressed in adult antennae, suggesting a candidate pheromone-degrading enzyme (PDE) to inactivate the sex pheromone components (Z)-11-hexadecenal and (Z)-9-hexadecenal. RNA sequencing data further demonstrated that a number of host plants they feed on could significantly upregulate the expression levels of HarmAOX1 in larvae. This study improves our understanding of insect aldehyde oxidases and insect-plant interactions.

  17. Effect of temperature stress on polyphenol oxidase activity in grains of some wheat cultivars

    International Nuclear Information System (INIS)

    Kayani, W.K.

    2011-01-01

    Color is a key quality trait of wheat-based products and polyphenol oxidase (PPO) is implicated to play a significant role in their undesirable darkening. Polyphenol oxidase catalyzes the oxidation of phenols to quinines, which auto oxidize and polymerize with amino acid of cellular proteins resulting brown and black pigmentation propounding reduced nutritional values. In present study, the PPO activity in 50 different Pakistani wheat cultivars was investigated and grouped into three categories viz; low, medium and high PPO activity cultivars. PPO is a heat labile enzyme. To investigate effect of heat stress, nine cultivars from each category were chosen for treatment at 30, 40 and 50 deg. C for 30, 60, and 120 minutes each. A substantial change was experienced in PPO activity as compared to room temperature. Two wheat cultivar Wafaq-2001 and AS-2002 showed a compromising attitude of minimum PPO activity at 30 deg. C for a period of 30 and 60 minutes of incubation. In general, an incubation of 30 deg. C or 60 deg. C (low or high) for a period of 30 minutes can be recommended for suppressing PPO activity. (author)

  18. Biogenic manganese oxide nanoparticle formation by a multimeric multicopper oxidase Mnx.

    Science.gov (United States)

    Romano, Christine A; Zhou, Mowei; Song, Yang; Wysocki, Vicki H; Dohnalkova, Alice C; Kovarik, Libor; Paša-Tolić, Ljiljana; Tebo, Bradley M

    2017-09-29

    Bacteria that produce Mn oxides are extraordinarily skilled engineers of nanomaterials that contribute significantly to global biogeochemical cycles. Their enzyme-based reaction mechanisms may be genetically tailored for environmental remediation applications or bioenergy production. However, significant challenges exist for structural characterization of the enzymes responsible for biomineralization. The active Mn oxidase in Bacillus sp. PL-12, Mnx, is a complex composed of a multicopper oxidase (MCO), MnxG, and two accessory proteins, MnxE and MnxF. MnxG shares sequence similarity with other, structurally characterized MCOs. MnxE and MnxF have no similarity to any characterized proteins. The ~200 kDa complex has been recalcitrant to crystallization, so its structure is unknown. Here, we show that native mass spectrometry defines the subunit topology and copper binding of Mnx, while high-resolution electron microscopy visualizes the protein and nascent Mn oxide minerals. These data provide critical structural information for understanding Mn biomineralization by such unexplored enzymes.Significant challenges exist for structural characterization of enzymes responsible for biomineralization. Here the authors show that native mass spectrometry and high resolution electron microscopy can define the subunit topology and copper binding of a manganese oxidizing complex, and describe early stage formation of its mineral products.

  19. Brain monoamine oxidase B and A in human parkinsonian dopamine deficiency disorders.

    Science.gov (United States)

    Tong, Junchao; Rathitharan, Gausiha; Meyer, Jeffrey H; Furukawa, Yoshiaki; Ang, Lee-Cyn; Boileau, Isabelle; Guttman, Mark; Hornykiewicz, Oleh; Kish, Stephen J

    2017-09-01

    See Jellinger (doi:10.1093/awx190) for a scientific commentary on this article. The enzyme monoamine oxidases (B and A subtypes, encoded by MAOB and MAOA, respectively) are drug targets in the treatment of Parkinson's disease. Inhibitors of MAOB are used clinically in Parkinson's disease for symptomatic purposes whereas the potential disease-modifying effect of monoamine oxidase inhibitors is debated. As astroglial cells express high levels of MAOB, the enzyme has been proposed as a brain imaging marker of astrogliosis, a cellular process possibly involved in Parkinson's disease pathogenesis as elevation of MAOB in astrocytes might be harmful. Since brain monoamine oxidase status in Parkinson's disease is uncertain, our objective was to measure, by quantitative immunoblotting in autopsied brain homogenates, protein levels of both monoamine oxidases in three different degenerative parkinsonian disorders: Parkinson's disease (n = 11), multiple system atrophy (n = 11), and progressive supranuclear palsy (n = 16) and in matched controls (n = 16). We hypothesized that if MAOB is 'substantially' localized to astroglial cells, MAOB levels should be generally associated with standard astroglial protein measures (e.g. glial fibrillary acidic protein). MAOB levels were increased in degenerating putamen (+83%) and substantia nigra (+10%, non-significant) in multiple system atrophy; in caudate (+26%), putamen (+27%), frontal cortex (+31%) and substantia nigra (+23%) of progressive supranuclear palsy; and in frontal cortex (+33%), but not in substantia nigra of Parkinson's disease, a region we previously reported no increase in astrocyte protein markers. Although the magnitude of MAOB increase was less than those of standard astrocytic markers, significant positive correlations were observed amongst the astrocyte proteins and MAOB. Despite suggestions that MAOA (versus MAOB) is primarily responsible for metabolism of dopamine in dopamine neurons, there was no loss of the

  20. The tau positron-emission tomography tracer AV-1451 binds with similar affinities to tau fibrils and monoamine oxidases.

    Science.gov (United States)

    Vermeiren, Céline; Motte, Philippe; Viot, Delphine; Mairet-Coello, Georges; Courade, Jean-Philippe; Citron, Martin; Mercier, Joël; Hannestad, Jonas; Gillard, Michel

    2018-02-01

    Lilly/Avid's AV-1451 is one of the most advanced tau PET tracers in the clinic. Although results obtained in Alzheimer's disease patients are compelling, discrimination of tracer uptake in healthy individuals and patients with supranuclear palsy (PSP) is less clear as there is substantial overlap of signal in multiple brain regions. Moreover, accurate quantification of [ 18 F]AV-1451 uptake in Alzheimer's disease may not be possible. The aim of the present study was to characterize the in vitro binding of AV-1451 to understand and identify potential off-target binding that could explain the poor discrimination observed in PSP patients. [ 3 H]AV-1451 and AV-1451 were characterized in in vitro binding assays using recombinant and native proteins/tissues from postmortem samples of controls and Alzheimer's disease and PSP patients. [ 3 H]AV-1451 binds to multiple sites with nanomolar affinities in brain homogenates and to tau fibrils isolated from Alzheimer's disease or PSP patients. [ 3 H]AV-1451 also binds with similarly high affinities in brain homogenates devoid of tau pathology. This unexpected binding was demonstrated to be because of nanomolar affinities of [ 3 H]AV-1451 for monoamine oxidase A and B enzymes. High affinity of AV-1451 for monoamine oxidase proteins may limit its utility as a tau PET tracer in PSP and Alzheimer's disease because of high levels of monoamine oxidase expression in brain regions also affected by tau deposition, especially if monoamine oxidase levels change over time or with a treatment intervention. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

  1. Lactate Biosensor Based on Cellulose Acetate Membrane Bound Lactate Oxidase

    Directory of Open Access Journals (Sweden)

    Suman

    2007-05-01

    Full Text Available Lactate biosensor was fabricated by immobilizing lactate oxidase in cellulose acetate membrane and by mounting over the sensing part of Pt electrode (working and connected to Ag/AgCl electrode (reference along with auxillary electrode through potentiostat. The enzyme electrode was anodically polarized at +400 mV to generate electrons from H2O2, which was formed from oxidation of serum lactate by immobilized lactate oxidase. The minimum detection limit of the electrode was 0.1mmoles/L and sensitivity of the sensor was 0.008 mA/mM/L lactate. Assay coefficients of variation were < 2% .A good correlation (r=0.99 was found between lactate values obtained by colorimetric method and lactate biosensor. The self-life of the biosensor was 18 days at 4ºC and enzyme electrode can be re-used 150 times without any significant loss in enzyme activity.

  2. Dual inhibitors of cholinesterases and monoamine oxidases for Alzheimer's disease.

    Science.gov (United States)

    Knez, Damijan; Sova, Matej; Košak, Urban; Gobec, Stanislav

    2017-05-01

    Accumulating evidence indicates a solid relationship between several enzymes and Alzheimer's disease. Cholinesterases and monoamine oxidases are closely associated with the disease symptomatology and progression and have been tackled simultaneously using several multifunctional ligands. This design strategy offers great chances to alter the course of Alzheimer's disease, in addition to alleviation of the symptoms. More than 15 years of research has led to the identification of various dual cholinesterase/monoamine oxidase inhibitors, while some showing positive outcomes in clinical trials, thus giving rise to additional research efforts in the field. The aim of this review is to provide an update on the novel dual inhibitors identified recently and to shed light on their therapeutic potential.

  3. Involvement of NADH Oxidase in Biofilm Formation in Streptococcus sanguinis.

    Directory of Open Access Journals (Sweden)

    Xiuchun Ge

    Full Text Available Biofilms play important roles in microbial communities and are related to infectious diseases. Here, we report direct evidence that a bacterial nox gene encoding NADH oxidase is involved in biofilm formation. A dramatic reduction in biofilm formation was observed in a Streptococcus sanguinis nox mutant under anaerobic conditions without any decrease in growth. The membrane fluidity of the mutant bacterial cells was found to be decreased and the fatty acid composition altered, with increased palmitic acid and decreased stearic acid and vaccenic acid. Extracellular DNA of the mutant was reduced in abundance and bacterial competence was suppressed. Gene expression analysis in the mutant identified two genes with altered expression, gtfP and Idh, which were found to be related to biofilm formation through examination of their deletion mutants. NADH oxidase-related metabolic pathways were analyzed, further clarifying the function of this enzyme in biofilm formation.

  4. Variations in epidermal cytochrome oxidase activity after local irradiation

    International Nuclear Information System (INIS)

    Itoiz, M.E.; Rey, B.M. de; Cabrini, R.L.

    1982-01-01

    Cytochrome oxidase activity was evaluated histochemically as an index of mitochondrial damage after local irradiation with X-rays. It was determined by microphotometry on the tail skin of newly born Wistar rats four days after irradiation with doses ranging from 2 to 16krad. The enzyme activity of the whole epidermis increased after irradiation, the increases being related to the increase in thickness of the epithelium which was observed as a response to irradiation injury. Within the dose range tested, the enzyme concentration (expressed per unit volume of tissue) decreased in relation to the dose applied. At the electron microscopy level, the cytochemical demonstration of cytochrome oxidase revealed an irregular reaction over the cristae, intramitochondrial vacuolization and partial homogenization of the matrix. Positive membrane fragments were seen around lipid droplets. This reaction confirms the mitochondrial origin of these previously observed radiation-induced vacuoles. (author)

  5. Glucose Oxidase Catalyzed Self-Assembly of Bioelectroactive Gold Nanostructures

    Science.gov (United States)

    2010-01-01

    polymer matrix), however, electrons generated at the FAD/FADH2 active site of glucose oxidase (GOx) must tunnel ca. 15 through the protein shell...described as a surface bound thiolate [33]. Recently, the presence of free thiol groups has been proposed as a mechanism for gold reduction in pure enzymes...simultaneously [38]. The oxidative polymerization of the amines proceeds simulta- neously with the formation of gold nanoparticles such that the polymerized amine

  6. Graphene-glucose oxidase bioanodes for enzymatic biofuel cells

    DEFF Research Database (Denmark)

    Tang, Jing; Werchmeister, Rebecka Maria Larsen; Engelbrekt, Christian

    2017-01-01

    as supporting material, polyethyleneimine (PEI) as linker and glucose oxidase (GOD) as the chosen enzyme. GOD can catalyze oxidation of glucose to gluconolactone, but needs a mediator to assist electron transfer between the enzyme and electrodes. The redox molecule ferrocene carboxylic acid (Fc...... and systematically investigated. The assembled EBFCs show good reproducibility. EBFCs provide maximum output power density 2.47 μW cm-2 at 35 ℃, indicating the optimized activity of EBFCs fed with glucose....

  7. Multiple controls affect arsenite oxidase gene expression in Herminiimonas arsenicoxydans

    Directory of Open Access Journals (Sweden)

    Coppée Jean-Yves

    2010-02-01

    Full Text Available Abstract Background Both the speciation and toxicity of arsenic are affected by bacterial transformations, i.e. oxidation, reduction or methylation. These transformations have a major impact on environmental contamination and more particularly on arsenic contamination of drinking water. Herminiimonas arsenicoxydans has been isolated from an arsenic- contaminated environment and has developed various mechanisms for coping with arsenic, including the oxidation of As(III to As(V as a detoxification mechanism. Results In the present study, a differential transcriptome analysis was used to identify genes, including arsenite oxidase encoding genes, involved in the response of H. arsenicoxydans to As(III. To get insight into the molecular mechanisms of this enzyme activity, a Tn5 transposon mutagenesis was performed. Transposon insertions resulting in a lack of arsenite oxidase activity disrupted aoxR and aoxS genes, showing that the aox operon transcription is regulated by the AoxRS two-component system. Remarkably, transposon insertions were also identified in rpoN coding for the alternative N sigma factor (σ54 of RNA polymerase and in dnaJ coding for the Hsp70 co-chaperone. Western blotting with anti-AoxB antibodies and quantitative RT-PCR experiments allowed us to demonstrate that the rpoN and dnaJ gene products are involved in the control of arsenite oxidase gene expression. Finally, the transcriptional start site of the aoxAB operon was determined using rapid amplification of cDNA ends (RACE and a putative -12/-24 σ54-dependent promoter motif was identified upstream of aoxAB coding sequences. Conclusion These results reveal the existence of novel molecular regulatory processes governing arsenite oxidase expression in H. arsenicoxydans. These data are summarized in a model that functionally integrates arsenite oxidation in the adaptive response to As(III in this microorganism.

  8. Biochemical Conservation and Evolution of Germacrene A Oxidase in Asteraceae*

    Science.gov (United States)

    Nguyen, Don Trinh; Göpfert, Jens Christian; Ikezawa, Nobuhiro; MacNevin, Gillian; Kathiresan, Meena; Conrad, Jürgen; Spring, Otmar; Ro, Dae-Kyun

    2010-01-01

    Sesquiterpene lactones are characteristic natural products in Asteraceae, which constitutes ∼8% of all plant species. Despite their physiological and pharmaceutical importance, the biochemistry and evolution of sesquiterpene lactones remain unexplored. Here we show that germacrene A oxidase (GAO), evolutionarily conserved in all major subfamilies of Asteraceae, catalyzes three consecutive oxidations of germacrene A to yield germacrene A acid. Furthermore, it is also capable of oxidizing non-natural substrate amorphadiene. Co-expression of lettuce GAO with germacrene synthase in engineered yeast synthesized aberrant products, costic acids and ilicic acid, in an acidic condition. However, cultivation in a neutral condition allowed the de novo synthesis of a single novel compound that was identified as germacrene A acid by gas and liquid chromatography and NMR analyses. To trace the evolutionary lineage of GAO in Asteraceae, homologous genes were further isolated from the representative species of three major subfamilies of Asteraceae (sunflower, chicory, and costus from Asteroideae, Cichorioideae, and Carduoideae, respectively) and also from the phylogenetically basal species, Barnadesia spinosa, from Barnadesioideae. The recombinant GAOs from these genes clearly showed germacrene A oxidase activities, suggesting that GAO activity is widely conserved in Asteraceae including the basal lineage. All GAOs could catalyze the three-step oxidation of non-natural substrate amorphadiene to artemisinic acid, whereas amorphadiene oxidase diverged from GAO displayed negligible activity for germacrene A oxidation. The observed amorphadiene oxidase activity in GAOs suggests that the catalytic plasticity is embedded in ancestral GAO enzymes that may contribute to the chemical and catalytic diversity in nature. PMID:20351109

  9. [THE INFLUENCE OF SEROTONIN TRANSPORTER AND MONOAMINE OXIDASE A GENES POLYMORPHISM ON PSYCHO-EMOTION AND KARYOLOGICAL STABILITY OF ATHLETES].

    Science.gov (United States)

    Kalaev, V N; Nechaeva, M S; Korneeva, O S; Cherenkov, D A

    2015-11-01

    The influence of polymorphism of the serotonin transporter and monoamine oxidase A genes, associated with man's aggressiveness on the psycho-emotional state and karyological status of single combat athletes. It was revealed that the carriers of less active ("short"), monoamine oxidase A gene variant have a high motivation to succeed and less rigidity and frustrated, compared to the carriers of more active ("long") version of the gene. Heterozygote carriers of less active ("short") variant of the serotonin transporter gene 5-HTTL had more physical aggression, guilt and were less frustrated compared with carriers of two long alleles. It has been revealed the association of studied genes with the karyological status of athletes. So fighters who are carriers of the short and long alleles of the serotonin transporter gene had more cells with nuclear abnormalities in the buccal epithelium than single combat athletes which both alleles were long.

  10. ENHANCING DIRECT ELECTRON TRANSFER OF GLUCOSE OXIDASE USING A GOLD NANOPARTICLE |TITANATE NANOTUBE NANOCOMPOSITE ON A BIOSENSOR

    International Nuclear Information System (INIS)

    Zhao, Ruoxia; Liu, Xiaoqiang; Zhang, Jiamei; Zhu, Jie; Wong, Danny K.Y.

    2015-01-01

    ABSTRACT: In this paper, we have developed a gold nanoparticle (GNP) decorated titanate nanotubes (TNT) nanocomposite that aids in the direct electron transfer of a large enzyme, such as glucose oxidase (GOD), in which the electroactive site of flavin adenine dinucleotide is deeply buried within the enzyme. The ionic liquid, brominated 1-decyl-3-methyl imidazole, was used to immobilise the nanocomposite and the enzyme on a glassy carbon electrode to further aid in the electron transfer between GOD and the electrode surface. Nafion was also added to anchor the biosensor scaffold. Initially, the tubiform geometry of titanate nanomaterials and the GNP-TNT nanocomposite was confirmed by microscopic and spectroscopic techniques before glucose oxidase was entrapped in the nanocomposite. Based on voltammetric results, this biosensor showed a strong electrocatalytic capability towards glucose (with a heterogeneous electron transfer rate constant of 7.1 s −1 at 180 mV s −1 ) and the calibration for glucose exhibited a high sensitivity (5.1 μA mM −1 ) and a wide linear range (0.01–1.2 mM). These results demonstrated superior analytical performance of our biosensor over others fabricated using bulkier TiO 2 nanoparticles or nanobundles, which could be attributed to a high degree of biocompatibility to glucose oxidase and electrical conductivity of the nanocomposite

  11. Direct and indirect effects of RNA interference against pyridoxal kinase and pyridoxine 5'-phosphate oxidase genes in Bombyx mori.

    Science.gov (United States)

    Huang, ShuoHao; Yao, LiLi; Zhang, JianYun; Huang, LongQuan

    2016-08-01

    Vitamin B6 comprises six interconvertible pyridine compounds (vitamers), among which pyridoxal 5'-phosphate is a coenzyme involved in a high diversity of biochemical reactions. Humans and animals obtain B6 vitamers from diet, and synthesize pyridoxal 5'-phosphate by pyridoxal kinase and pyridoxine 5'-phosphate oxidase. Currently, little is known on how pyridoxal 5'-phosphate biosynthesis is regulated, and pyridoxal 5'-phosphate is supplied to meet their requirement in terms of cofactor. Bombyx mori is a large silk-secreting insect, in which protein metabolism is most active, and the vitamin B6 demand is high. In this study, we successfully down-regulated the gene expression of pyridoxal kinase and pyridoxine 5'-phosphate oxidase by body cavity injection of synthesized double-stranded small interfering RNA to 5th instar larvae of Bombyx mori, and analyzed the gene transcription levels of pyridoxal 5'-phosphate dependent enzymes, phosphoserine aminotransferase and glutamic-oxaloacetic transaminase. Results show that the gene expression of pyridoxal kinase and pyridoxine 5'-phosphate oxidase has a greater impact on the gene transcription of enzymes using pyridoxal 5'-phosphate as a cofactor in Bombyx mori. Our study suggests that pyridoxal 5'-phosphate biosynthesis and dynamic balance may be regulated by genetic networks. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Export of functional Streptomyces coelicolor alditol oxidase to the periplasm or cell surface of Escherichia coli and its application in whole-cell biocatalysis

    NARCIS (Netherlands)

    van Bloois, Edwin; Winter, Remko T.; Janssen, Dick B.; Fraaije, Marco W.

    Streptomyces coelicolor A3(2) alditol oxidase (AldO) is a soluble monomeric flavoprotein in which the flavin cofactor is covalently linked to the polypeptide chain. AldO displays high reactivity towards different polyols such as xylitol and sorbitol. These characteristics make AldO industrially

  13. Arthrobacter P 1, a Fast Growing Versatile Methylotroph with Amine Oxidase as a Key Enzyme in the Metabolism of Methylated Amines

    NARCIS (Netherlands)

    Dijken, J.P. van; Veenhuis, M.; Harder, W.

    1981-01-01

    A facultative methylotrophic bacterium was isolated from enrichment cultures containing methylamine as the sole carbon source. It was tentatively identified as an Arthrobacter species. Extracts of cells grown on methylamine or ethylamine contained high levels of amine oxidase (E.C. 1.4.3) activity.

  14. NADPH oxidase and redox status in amygdala, hippocampus and cortex of male Wistar rats in an animal model of post-traumatic stress disorder.

    Science.gov (United States)

    Petrovic, Romana; Puskas, Laslo; Jevtic Dozudic, Gordana; Stojkovic, Tihomir; Velimirovic, Milica; Nikolic, Tatjana; Zivkovic, Milica; Djorovic, Djordje J; Nenadovic, Milutin; Petronijevic, Natasa

    2018-05-26

    Post-traumatic stress disorder (PTSD) is a highly prevalent and impairing disorder. Oxidative stress is implicated in its pathogenesis. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is an important source of free radicals. The aim of the study was to assess oxidative stress parameters, activities of respiratory chain enzymes, and the expression of NADPH oxidase subunits (gp91phox, p22phox, and p67phox) in the single prolonged stress (SPS) animal model of PTSD. Twenty-four (12 controls; 12 subjected to SPS), 9-week-old, male Wistar rats were used. SPS included physical restraint, forced swimming, and ether exposure. The rats were euthanized seven days later. Cortex, hippocampus, amygdala, and thalamus were dissected. Malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), Complex I, and cytochrome C oxidase were measured using spectrophotometric methods, while the expression of NADPH oxidase subunits was determined by Western blot. Increased MDA and decreased GSH concentrations were found in the amygdala and hippocampus of the SPS rats. SOD activity was decreased in amygdala and GPx was decreased in hippocampus. Increased expression of the NADPH oxidase subunits was seen in amygdala, while mitochondrial respiratory chain enzyme expression was unchanged both in amygdala and hippocampus. In the cortex concentrations of MDA and GSH were unchanged despite increased Complex I and decreased GPx, while in the thalamus no change of any parameter was noticed. We conclude that oxidative stress is present in hippocampus and amygdala seven days after the SPS procedure. NADPH oxidase seems to be a main source of free radicals in the amygdala.

  15. On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase

    Czech Academy of Sciences Publication Activity Database

    Shleev, S.; Andoralov, V.; Falk, M.; Reimann, C. T.; Ruzgas, T.; Srnec, Martin; Ryde, U.; Rulíšek, Lubomír

    2012-01-01

    Roč. 24, č. 7 (2012), s. 1524-1540 ISSN 1040-0397 Grant - others:7th Framework Program(XE) NMP4-SL-2009-229255 Institutional research plan: CEZ:AV0Z40550506 Keywords : bilirubin oxidase * intramolecular electron transfer * rate-limiting catalytic step * reorganization energy * QM/MM calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.817, year: 2012

  16. Identification, expression, and taxonomic distribution of alternative oxidases in non-angiosperm plants.

    Science.gov (United States)

    Neimanis, Karina; Staples, James F; Hüner, Norman P A; McDonald, Allison E

    2013-09-10

    Alternative oxidase (AOX) is a terminal ubiquinol oxidase present in the respiratory chain of all angiosperms investigated to date, but AOX distribution in other members of the Viridiplantae is less clear. We assessed the taxonomic distribution of AOX using bioinformatics. Multiple sequence alignments compared AOX proteins and examined amino acid residues involved in AOX catalytic function and post-translational regulation. Novel AOX sequences were found in both Chlorophytes and Streptophytes and we conclude that AOX is widespread in the Viridiplantae. AOX multigene families are common in non-angiosperm plants and the appearance of AOX1 and AOX2 subtypes pre-dates the divergence of the Coniferophyta and Magnoliophyta. Residues involved in AOX catalytic function are highly conserved between Chlorophytes and Streptophytes, while AOX post-translational regulation likely differs in these two lineages. We demonstrate experimentally that an AOX gene is present in the moss Physcomitrella patens and that the gene is transcribed. Our findings suggest that AOX will likely exert an influence on plant respiration and carbon metabolism in non-angiosperms such as green algae, bryophytes, liverworts, lycopods, ferns, gnetophytes, and gymnosperms and that further research in these systems is required. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Biogenic manganese oxide nanoparticle formation by a multimeric multicopper oxidase Mnx

    Energy Technology Data Exchange (ETDEWEB)

    Romano, Christine A.; Zhou, Mowei; Song, Yang; Wysocki, Vicki H.; Dohnalkova, Alice C.; Kovarik, Libor; Paša-Tolić, Ljiljana; Tebo, Bradley M.

    2017-09-29

    Bacteria that produce Mn oxides are extraordinarily skilled engineers of nanomaterials that contribute significantly to global biogeochemical cycles. Their enzyme-based reaction mechanisms may be genetically tailored for environmental remediation applications or bioenergy production. However, significant challenges exist for structural characterization of the enzymes responsible for biomineralization. The active Mn oxidase, Mnx, in Bacillus sp. PL-12 is a complex composed of a multicopper oxidase (MCO), MnxG, and two accessory proteins MnxE and MnxF. MnxG shares sequence similarity with other, structurally characterized MCOs. However, MnxE and MnxF have no similarity to any characterized proteins. The ~200 kDa complex has been recalcitrant to crystallization, so its structure is unknown. In this study, native mass spectrometry defines the subunit topology and copper binding of the Mnx complex, while high resolution electron microscopy visualizes the protein and nascent Mn oxide minerals. These data provide critical structural information for conceptualizing how Mnx produces nanoparticulate Mn oxides.

  18. Dithiocarbamates are teratogenic to developing zebrafish through inhibition of lysyl oxidase activity

    International Nuclear Information System (INIS)

    Boxtel, Antonius L. van; Kamstra, Jorke H.; Fluitsma, Donna M.; Legler, Juliette

    2010-01-01

    Dithiocarbamates (DTCs) are a class of compounds that are extensively used in agriculture as pesticides. As such, humans and wildlife are undoubtedly exposed to these chemicals. Although DTCs are thought to be relatively safe due to their short half lives, it is well established that they are teratogenic to vertebrates, especially to fish. In zebrafish, these teratogenic effects are characterized by distorted notochord development and shortened anterior to posterior axis. DTCs are known copper (Cu) chelators but this does not fully explain the observed teratogenic effects. We show here that DTCs cause malformations in zebrafish that highly resemble teratogenic effects observed by direct inhibition of a group of cuproenzymes termed lysyl oxidases (LOX). Additionally, we demonstrate that partial knockdown of three LOX genes, lox, loxl1 and loxl5b, sensitizes the developing embryo to DTC exposure. Finally, we show that DTCs directly inhibit zebrafish LOX activity in an ex vivo amine oxidase assay. Taken together, these results provide the first evidence that DTC induced teratogenic effects are, at least in part, caused by direct inhibition of LOX activity.

  19. Nuclear expression of lysyl oxidase enzyme is an independent prognostic factor in rectal cancer patients

    DEFF Research Database (Denmark)

    Liu, Na; Cox, Thomas R; Cui, Weiyingqi

    2017-01-01

    Emerging evidence has implicated a pivotal role for lysyl oxidase (LOX) in cancer progression and metastasis. Whilst the majority of work has focused on the extracellular matrix cross-linking role of LOX, the exact function of intracellular LOX localisation remains unclear. In this study, we anal...... the nucleus of colon cancer cell lines by confocal microscopy and Western blot. Our results show a powerful link between nuclear LOX expression in tumours and patient survival, and offer a promising prognostic biomarker for rectal cancer patients....... analysed the LOX expression patterns in the nuclei of rectal cancer patient samples and determined the clinical significance of this expression. Nuclear LOX expression was significantly increased in patient lymph node metastases compared to their primary tumours. High nuclear LOX expression in tumours......Emerging evidence has implicated a pivotal role for lysyl oxidase (LOX) in cancer progression and metastasis. Whilst the majority of work has focused on the extracellular matrix cross-linking role of LOX, the exact function of intracellular LOX localisation remains unclear. In this study, we...

  20. Cloning, expression, and enzymatic activity evaluation of cholesterol oxidase gene isolated from a native Rhodococcus sp.

    Directory of Open Access Journals (Sweden)

    Hamed Esmaeil Lashgarian

    2016-10-01

    Full Text Available Cholesterol oxidase (CHO is one of the valuable enzymes that play an important role in: measurement of serum cholesterol, food industry as a biocatalyst and agriculture as a biological larvicide. This enzyme was produced by several bacterial strains. Wild type enzyme produced by Rhodococcus sp. secret two forms of CHO enzyme: extra cellular and membrane bound type which its amount is low and unstable. The goal of the study was cloning, expression, and enzymatic activity evaluation of cholesterol oxidase gene isolated from a native Rhodococcus sp. CHO gene was isolated from native bacteria and cloned into pET23a. In the next step, the construct was expressed in E.coli BL21 and induced by different concentration of IPTG ranges from 0.1 - 0.9 mM. This gene contains 1642 bp and encodes a protein consists of 533 amino acids. It has about 96 % homology with CHO gene isolated from Rhodococcus equi. The high expression was obtained in 0.5 mM concentration of IPTG after 4 hour induction. This recombinant enzyme had a molecular weight of 55 kDa, that secretion of intra cellular type is much more than extracellular form. The optimum pH and temperature conditions for the recombinant enzyme were 7.5 and 45°C, respectively. CHO enzyme obtained from Rhodococcus sp. is a cheap enzyme with medical and industrial applications that can be produced easily and purified in large scale with simple methods.

  1. Direct comparison of gluco-oligosaccharide oxidase variants and glucose oxidase: substrate range and H2O2 stability.

    Science.gov (United States)

    Vuong, Thu V; Foumani, Maryam; MacCormick, Benjamin; Kwan, Rachel; Master, Emma R

    2016-11-21

    Glucose oxidase (GO) activity is generally restricted to glucose and is susceptible to inactivation by H 2 O 2 . By comparison, the Y300A variant of gluco-oligosaccharide oxidase (GOOX) from Sarocladium strictum showed broader substrate range and higher H 2 O 2 stability. Specifically, Y300A exhibited up to 40 times higher activity on all tested sugars except glucose, compared to GO. Moreover, fusion of the Y300A variant to a family 22 carbohydrate binding module from Clostridium thermocellum (CtCBM22A) nearly doubled its catalytic efficiency on glucose, while retaining significant activity on oligosaccharides. In the presence of 200 mM of H 2 O 2 , the recombinant CtCBM22A_Y300A retained 80% of activity on glucose and 100% of activity on cellobiose, the preferred substrate for this enzyme. By contrast, a commercial glucose oxidase reported to contain ≤0.1 units catalase/ mg protein, retained 60% activity on glucose under the same conditions. GOOX variants appear to undergo a different mechanism of inactivation, as a loss of histidine instead of methionine was observed after H 2 O 2 incubation. The addition of CtCBM22A also promoted functional binding of the fusion enzyme to xylan, facilitating its simultaneous purification and immobilization using edible oat spelt xylan, which might benefit the usage of this enzyme preparation in food and baking applications.

  2. Protein structural development of threadfin bream ( Nemipterus spp.) surimi gels induced by glucose oxidase.

    Science.gov (United States)

    Wang, Lei; Fan, Daming; Fu, Lulu; Jiao, Xidong; Huang, Jianlian; Zhao, Jianxin; Yan, Bowen; Zhou, Wenguo; Zhang, Wenhai; Ye, Weijian; Zhang, Hao

    2018-01-01

    This study investigated the effect of glucose oxidase on the gel properties of threadfin bream surimi. The gel strength of surimi increased with the addition of 0.5‰ glucose oxidase after two-step heating. Based on the results of the chemical interactions, the hydrophobic interaction and disulfide bond of glucose oxidase-treated surimi samples increased compared with the control samples at the gelation temperature and gel modori temperature. The surface hydrophobicity of samples with glucose oxidase and glucose increased significantly ( p glucose oxidase induced more α-helixes to turn into a more elongated random and flocculent structure. Glucose oxidase changes the secondary structure of the surimi protein, making more proteins depolarize and stretch and causing actomyosin to accumulate to each other, resulting in the formation of surimi gel.

  3. Amine oxidases as important agents of pathological processes of rhabdomyolysis in rats.

    Science.gov (United States)

    Gudkova, O O; Latyshko, N V; Shandrenko, S G

    2016-01-01

    In this study we have tested an idea on the important role of amine oxidases (semicarbazide-sensitive amine oxidase, diamine oxidase, polyamine oxidase) as an additional source of oxidative/carbonyl stress under glycerol-induced rhabdomyolysis, since the enhanced formation of reactive oxygen species and reactive carbonyl species in a variety of tissues is linked to various diseases. In our experiments we used the sensitive fluorescent method devised for estimation of amine oxidases activity in the rat kidney and thymus as targeted organs under rhabdomyolysis. We have found in vivo the multiple rises in activity of semicarbazide-sensitive amine oxidase, diamine oxidase, polyamine oxidase (2-4.5 times) in the corresponding cell fractions, whole cells or their lysates at the 3-6th day after glycerol injection. Aberrant antioxidant activities depended on rhabdomyolysis stage and had organ specificity. Additional treatment of animals with metal chelator ‘Unithiol’ adjusted only the activity of antioxidant enzymes but not amine oxidases in both organs. Furthermore the in vitro experiment showed that Fenton reaction (hydrogen peroxide in the presence of iron) products alone had no effect on semicarbazide-sensitive amine oxidase activity in rat liver cell fraction whereas supplementation with methylglyoxal resulted in its significant 2.5-fold enhancement. Combined action of the both agents had additive effect on semicarbazide-sensitive amine oxidase activity. We can assume that biogenic amine and polyamine catabolism by amine oxidases is upregulated by oxidative and carbonyl stress factors directly under rhabdomyolysis progression, and the increase in catabolic products concentration contributes to tissue damage in glycerol-induced acute renal failure and apoptosis stimulation in thymus.

  4. Up-Streaming Process for Glucose Oxidase by Thermophilic Penicillium sp. in Shake Flask

    OpenAIRE

    Muhammad Mohsin JAVED; Aroosh SHABIR; Sana ZAHOOR; Ikram UL-HAQ

    2012-01-01

    The present study is concerned with the production of glucose oxidase (GOD) from thermophilic Penicillium sp. in 250 mL shake flask. Fourteen different strains of thermophilic Penicillium sp. were isolated from the soil and were screened for glucose oxidase production. IIBP-13 strain gave maximum extra-cellular glucose oxidase production as compared to other isolates. Effect of submerged fermentation in shaking and static conditions, different carbon sources and incubation period on the produ...

  5. Gold-Coated M13 Bacteriophage as a Template for Glucose Oxidase Biofuel Cells with Direct Electron Transfer.

    Science.gov (United States)

    Blaik, Rita A; Lan, Esther; Huang, Yu; Dunn, Bruce

    2016-01-26

    Glucose oxidase-based biofuel cells are a promising source of alternative energy for small device applications, but still face the challenge of achieving robust electrical contact between the redox enzymes and the current collector. This paper reports on the design of an electrode consisting of glucose oxidase covalently attached to gold nanoparticles that are assembled onto a genetically engineered M13 bacteriophage using EDC-NHS chemistry. The engineered phage is modified at the pIII protein to attach onto a gold substrate and serves as a high-surface-area template. The resulting "nanomesh" architecture exhibits direct electron transfer (DET) and achieves a higher peak current per unit area of 1.2 mA/cm(2) compared to most other DET attachment schemes. The final enzyme surface coverage on the electrode was calculated to be approximately 4.74 × 10(-8) mol/cm(2), which is a significant improvement over most current glucose oxidase (GOx) DET attachment methods.

  6. Effective immobilization of glucose oxidase on chitosan submicron particles from gladius of Todarodes pacificus for glucose sensing.

    Science.gov (United States)

    Anusha, J R; Fleming, Albin T; Kim, Hee-Je; Kim, Byung Chul; Yu, Kook-Hyun; Raj, C Justin

    2015-08-01

    An effective enzymatic glucose biosensor was developed by immobilizing glucose oxidase on chitosan submicron particles synthesized from the gladius of Todarodes pacificus (GCSP). The chemically synthesized chitosan from gladius was pulverized to submicron particles by ball milling technique, which was further characterized and compared with the standard chitosan (SCS). The degree of deacetylation of GCSP was determined using FTIR spectroscopy which was comparable to the value of standard chitosan. The glucose oxidase (GOx) was immobilized over GCSP on porous zinc oxide/platinum nanoparticle (ZnO/Pt) based electrode. The morphological and structural properties of the electrodes were analyzed using scanning electron microscopy and X-ray diffraction analysis. The glucose sensing behavior of electrode was estimated using electrochemical analysis and showed an excellent analytical performance. The electrode ZnO/Pt/GCSP conjugated with GOx displayed high sensitivity (88.76 μA mM(-1) cm(-2)) with low detection limit in short response time. In addition, the very low value of Michaelis-Menten constant for GCSP based electrode contributes a better affinity of the electrode surface towards glucose oxidase. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. The conserved baculovirus protein p33 (Ac92) is a flavin adenine dinucleotide-linked sulfhydryl oxidase

    International Nuclear Information System (INIS)

    Long, C.M.; Rohrmann, G.F.; Merrill, G.F.

    2009-01-01

    Open reading frame 92 of the Autographa californica baculovirus (Ac92) is one of about 30 core genes present in all sequenced baculovirus genomes. Computer analyses predicted that the Ac92 encoded protein (called p33) and several of its baculovirus orthologs were related to a family of flavin adenine dinucleotide (FAD)-linked sulfhydryl oxidases. Alignment of these proteins indicated that, although they were highly diverse, a number of amino acids in common with the Erv1p/Alrp family of sulfhydryl oxidases are present. Some of these conserved amino acids are predicted to stack against the isoalloxazine and adenine components of FAD, whereas others are involved in electron transfer. To investigate this relationship, Ac92 was expressed in bacteria as a His-tagged fusion protein, purified, and characterized both spectrophotometrically and for its enzymatic activity. The purified protein was found to have the color (yellow) and absorption spectrum consistent with it being a FAD-containing protein. Furthermore, it was demonstrated to have sulfhydryl oxidase activity using dithiothreitol and thioredoxin as substrates.

  8. Barley polyamine oxidase: Characterisation and analysis of the cofactor and the N-terminal amino acid sequence

    DEFF Research Database (Denmark)

    Radova, A.; Sebela, M.; Galuszka, P.

    2001-01-01

    This paper reports the first purification method developed for the isolation of an homogeneous polyamine oxidase (PAO) from etiolated barley seedlings. The crude enzyme preparation was obtained after initial precipitation of the extract with protamine sulphate and ammonium sulphate. The enzyme...... was further confirmed by measuring the fluorescence spectra, Barley PAO is an acidic protein (pI 5.4) containing 3% of neutral sugars: its molecular mass determined by SDS-PAGE was 56 kDa, whilst gel permeation chromatography revealed the higher value of 76 kDa. The N-terminal amino acid sequence of barley...... PAO shows a high degree of similarity to that of maize PAO and to several other flavoprotein oxidases. The polyamines spermine and spermidine were the only two substrates of the enzyme with K-m values 4 x 10(-5) and 3 x 10(-5) M and pH optima of 5.0 and 6.0, respectively. Barley polyamine oxidase...

  9. Inducible bilirubin oxidase: A novel function for the mouse cytochrome P450 2A5

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Bakar, A' edah, E-mail: a.abubakar@uq.edu.au [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Arthur, Dionne Maioha [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Adelaide (Australia); Aganovic, Simona [Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, Box 578, S-751 23 Uppsala (Sweden); Ng, Jack C. [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Adelaide (Australia); Lang, Matti A. [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, Box 578, S-751 23 Uppsala (Sweden)

    2011-11-15

    We have previously shown that bilirubin (BR), a breakdown product of haem, is a strong inhibitor and a high affinity substrate of the mouse cytochrome P450 2A5 (CYP2A5). The antioxidant BR, which is cytotoxic at high concentrations, is potentially useful in cellular protection against oxygen radicals if its intracellular levels can be strictly controlled. The mechanisms that regulate cellular BR levels are still obscure. In this paper we provide preliminary evidence for a novel function of CYP2A5 as hepatic 'BR oxidase'. A high-performance liquid chromatography/electrospray ionisation mass spectrometry screening showed that recombinant yeast microsomes expressing the CYP2A5 oxidise BR to biliverdin, as the main metabolite, and to three other smaller products with m/z values of 301, 315 and 333. The metabolic profile is significantly different from that of chemical oxidation of BR. In chemical oxidation the smaller products were the main metabolites. This suggests that the enzymatic reaction is selective, towards biliverdin production. Bilirubin treatment of primary hepatocytes increased the CYP2A5 protein and activity levels with no effect on the corresponding mRNA. Co-treatment with cycloheximide (CHX), a protein synthesis inhibitor, resulted in increased half-life of the CYP2A5 compared to cells treated only with CHX. Collectively, the observations suggest that the CYP2A5 is potentially an inducible 'BR oxidase' where BR may accelerate its own metabolism through stabilization of the CYP2A5 protein. It is possible that this metabolic pathway is potentially part of the machinery controlling intracellular BR levels in transient oxidative stress situations, in which high amounts of BR are produced. -- Highlights: Black-Right-Pointing-Pointer CYP2A5 metabolizes bilirubin to biliverdin and dipyrroles. Black-Right-Pointing-Pointer Bilirubin increased the hepatic CYP2A5 protein and activity levels. Black-Right-Pointing-Pointer Bilirubin does not

  10. Diamine oxidase determination in serum - Low assay reproducibility and misclassification of healthy subjects

    DEFF Research Database (Denmark)

    Schnoor, Heidi Julius; Mosbech, Holger Fausbøll; Skov, Per Stahl

    2013-01-01

    Summary Background: Impaired histamine degradation based on reduced diamine oxidase (DAO) activity has been suggested to cause symptoms mimicking an allergic reaction. Aim: To test whether patients presenting with possible histamine-induced symptoms have a low serum activity of DAO compared...... in the test kit was 86 %. Only 11 out of the 31 subjects were uniformly classified in all three runs. Among the healthy subjects, 9–12 out of 18 showed reduced or highly reduced activities; in the patient group, 0–5 out of 11 showed reduced or highly reduced activities in the three measurements...... normal range caused misclassification in more than half of the cases. Using a commercial immunoassay, it was not possible to distinguish healthy subjects from patients showing potentially histamine-induced symptoms....

  11. Direct electrochemistry and electrocatalysis of glucose oxidase on three-dimensional interpenetrating, porous graphene modified electrode

    International Nuclear Information System (INIS)

    Cui, Min; Xu, Bing; Hu, Chuangang; Shao, Hui Bo; Qu, Liangti

    2013-01-01

    Direct electrochemistry of glucose oxidase (GOD) on three-dimensional (3D) interpenetrating porous graphene electrodes has been reported, which have been fabricated by one-step electrochemical reduction of graphene oxide (GO) from its aqueous suspension. The electrochemically reduced GO (ERGO) modified electrodes exhibited excellent electron transfer properties for GOD and enhanced the enzyme activity and stability by the assistance of chitosan. The immobilized GOD shows a fast electron transfer with the rate constant (k s ) of 6.05 s −1 . It is worth mentioning that in the air-saturated phosphate buffer solution without any mediator, the resultant modified electrodes exhibited low detection limit of 1.7 μM with wide linear range of 0.02–3.2 mM and high sensitivity and high selectivity for measuring glucose. It would also be extended to various enzymes and bioactive molecules to develop the biosensor or other bio-electrochemical devices

  12. Characterization of water-forming NADH oxidases for co-factor regeneration

    DEFF Research Database (Denmark)

    Rehn, Gustav; Pedersen, Asbjørn Toftgaard; J. Charnock, Simon

    an environmentaland economic perspective [1]. Alcohol dehydrogenases (ADH) offer one such alternative. However, the reaction requires the oxidized nicotinamide co-factor (NAD+) that must be recycled due to its high cost contribution. One regeneration method that offers certain advantages is the oxidation of NADH......Traditional chemical methods for alcohol oxidation are often associated with issues such as high consumption of expensive oxidizing agents, generation of metal waste and the use of environmentally undesirable organic solvents. Developing green, selective catalysts is therefore important from...... using water forming NADH oxidases (NOX-2). The implementation of the ADH/NOX system for alcohol oxidation, however, requires consideration of several different issues. Enzyme activity and stability at relevant pH and temperature conditions, but also the tolerance to the substrates and products present...

  13. Molecular evolution of the polyamine oxidase gene family in Metazoa

    Directory of Open Access Journals (Sweden)

    Polticelli Fabio

    2012-06-01

    Full Text Available Abstract Background Polyamine oxidase enzymes catalyze the oxidation of polyamines and acetylpolyamines. Since polyamines are basic regulators of cell growth and proliferation, their homeostasis is crucial for cell life. Members of the polyamine oxidase gene family have been identified in a wide variety of animals, including vertebrates, arthropodes, nematodes, placozoa, as well as in plants and fungi. Polyamine oxidases (PAOs from yeast can oxidize spermine, N1-acetylspermine, and N1-acetylspermidine, however, in vertebrates two different enzymes, namely spermine oxidase (SMO and acetylpolyamine oxidase (APAO, specifically catalyze the oxidation of spermine, and N1-acetylspermine/N1-acetylspermidine, respectively. Little is known about the molecular evolutionary history of these enzymes. However, since the yeast PAO is able to catalyze the oxidation of both acetylated and non acetylated polyamines, and in vertebrates these functions are addressed by two specialized polyamine oxidase subfamilies (APAO and SMO, it can be hypothesized an ancestral reference for the former enzyme from which the latter would have been derived. Results We analysed 36 SMO, 26 APAO, and 14 PAO homologue protein sequences from 54 taxa including various vertebrates and invertebrates. The analysis of the full-length sequences and the principal domains of vertebrate and invertebrate PAOs yielded consensus primary protein sequences for vertebrate SMOs and APAOs, and invertebrate PAOs. This analysis, coupled to molecular modeling techniques, also unveiled sequence regions that confer specific structural and functional properties, including substrate specificity, by the different PAO subfamilies. Molecular phylogenetic trees revealed a basal position of all the invertebrates PAO enzymes relative to vertebrate SMOs and APAOs. PAOs from insects constitute a monophyletic clade. Two PAO variants sampled in the amphioxus are basal to the dichotomy between two well supported

  14. Estrogen inhibits lysyl oxidase and decreases mechanical function in engineered ligaments.

    Science.gov (United States)

    Lee, Cassandra A; Lee-Barthel, Ann; Marquino, Louise; Sandoval, Natalie; Marcotte, George R; Baar, Keith

    2015-05-15

    Women are more likely to suffer an anterior cruciate ligament (ACL) rupture than men, and the incidence of ACL rupture in women rises with increasing estrogen levels. We used an engineered ligament model to determine how an acute rise in estrogen decreases the mechanical properties of ligaments. Using fibroblasts isolated from human ACLs from male or female donors, we engineered ligaments and determined that ligaments made from female ACL cells had more collagen and were equal in strength to those made from male ACL cells. We then treated engineered ligaments for 14 days with low (5 pg/ml), medium (50 pg/ml), or high (500 pg/ml) estrogen, corresponding to the range of in vivo serum estrogen concentrations and found that collagen within the grafts increased without a commensurate increase in mechanical strength. Mimicking the menstrual cycle, with 12 days of low estrogen followed by 2 days of physiologically high estrogen, resulted in a decrease in engineered ligament mechanical function with no change in the amount of collagen in the graft. The decrease in mechanical stiffness corresponded with a 61.7 and 76.9% decrease in the activity of collagen cross-linker lysyl oxidase with 24 and 48 h of high estrogen, respectively. Similarly, grafts treated with the lysyl oxidase inhibitor β-aminoproprionitrile (BAPN) for 24 h showed a significant decrease in ligament mechanical strength [control (CON) = 1.58 ± 0.06 N; BAPN = 1.06 ± 0.13 N] and stiffness (CON = 7.7 ± 0.46 MPa; BAPN = 6.1 ± 0.71 MPa) without changing overall collagen levels (CON = 396 ± 11.5 μg; BAPN = 382 ± 11.6 μg). Together, these data suggest that the rise in estrogen during the follicular phase decreases lysyl oxidase activity in our engineered ligament model and if this occurs in vivo may decrease the stiffness of ligaments and contribute to the elevated rate of ACL rupture in women. Copyright © 2015 the American Physiological Society.

  15. Key role of alternative oxidase in lovastatin solid-state fermentation.

    Science.gov (United States)

    Pérez-Sánchez, Ailed; Uribe-Carvajal, Salvador; Cabrera-Orefice, Alfredo; Barrios-González, Javier

    2017-10-01

    Lovastatin is a commercially important secondary metabolite produced by Aspergillus terreus, either by solid-state fermentation or by submerged fermentation. In a previous work, we showed that reactive oxygen species (ROS) accumulation in idiophase positively regulates lovastatin biosynthetic genes. In addition, it has been found that lovastatin-specific production decreases with aeration in solid-state fermentation (SSF). To study this phenomenon, we determined ROS accumulation during lovastatin SSF, under high and low aeration conditions. Paradoxically, high aeration caused lower ROS accumulation, and this was the underlying reason of the aeration effect on lovastatin production. Looking for a mechanism that is lowering ROS production under those conditions, we studied alternative respiration. The alternative oxidase provides an alternative route for electrons passing through the electron transport chain to reduce oxygen. Here, we showed that an alternative oxidase (AOX) is expressed in SSF, and only during idiophase. It was shown that higher aeration induces higher alternative respiration (AOX activity), and this is a mechanism that limits ROS generation and keeps them within healthy limits and adequate signaling limits for lovastatin production. Indeed, the aox gene was induced in idiophase, i.e., at the time of ROS accumulation. Moreover, exogenous ROS (H 2 O 2 ), added to lovastatin solid-state fermentation, induced higher AOX activity. This suggests that high O 2 availability in SSF generates dangerously high ROS, so alternative respiration is induced in SSF, indirectly favoring lovastatin production. Conversely, alternative respiration was not detected in lovastatin-submerged fermentation (SmF), although exogenous ROS also induced relatively low AOX activity in SmF.

  16. Iododerivative of pargyline: A potential tracer for the exploration of monoamine oxidase sites by SPECT

    International Nuclear Information System (INIS)

    Lena, Isabelle; Ombetta, Jean-Edouard; Chalon, Sylvie; Dognon, Anne-Marie; Baulieu, Jean-Louis; Frangin, Yves; Garreau, Lucette; Besnard, Jean-Claude; Guilloteau, Denis

    1995-01-01

    Monoamine oxidases are important in the regulation of monoaminergic neurotransmission. An increase in monoamine oxidase B (MAO B) has been observed in some neurodegenerative diseases, and therefore quantification of cerebral MAO B activity by SPECT would be useful for the diagnosis and therapeutic follow-up of these disorders. We have developed an iodinated derivative of pargyline, a selective inhibitor of MAO B, in order to explore this enzyme by SPECT. Stable bromo and iodo derivatives of pargyline were synthesized and chemically characterized. The radioiodinated ligand [ 125 I]-2-iodopargyline was obtained with high specific activity from the bromo precursor by nucleophilic exchange. Affinity and selectivity of 2-iodopargyline were tested in vitro. Biodistribution study of [ 125 I]-2-iodopargyline was performed in rats. Radioiodinated ligand were obtained in a no-carrier-added form. 2-iodopargyline has a higher in vitro affinity for MAO B than pargyline. However, the in vitro selectivity for MAO B was better for pargyline than for 2-iodopargyline. Ex vivo autoradiographic studies and in vivo saturation studies with selective inhibitors of MAO showed that the cerebral biodistribution of [ 125 I]-2-iodopargyline in the rat is consistent with high level binding to MAO B sites in the pineal gland and in the thalamus. In conclusion, 2-iodopargyline preferentially binds in vivo to MAO B sites with high affinity. However, its selectivity for MAO B in rats is not very high, whereas this ligand binds to a lesser extent to MAO A. It will be then of great value to evaluate the specificity of 2-iodopargyline in humans. This new ligand labeled with 123 I should therefore be a suitable tool for SPECT exploration of MAO B in the human brain

  17. Glucose oxidase immobilization onto carbon nanotube networking

    International Nuclear Information System (INIS)

    Karachevtsev, V.A.; Glamazda, A.Yu.; Zarudnev, E.S.; Karachevtsev, M.V.; Leontiev, V.S.; Linnik, A.S.; Plokhotnichenko, A.M.; Stepanian, S.G.; Lytvyn, O.S.

    2012-01-01

    The efficient immobilization of GOX onto a carbon nanotube network through the molecular interface formed by PSE is carried out. This conclusion is based on the analysis of AFM images of the network with the adsorbed enzyme, whose globules locate mainly along a nanotube. The band corresponding to the high-frequency component of the G mode in the RR spectrum of the nanotube with adsorbed PSE is downshifted by 0.7 cm -1 relative to this band in the spectrum of pristine nanotubes. The analysis of the intensities of bands assigned to the RBM of nanotubes with adsorbed PSE in comparison with the spectrum of pristine SWNTs revealed the intensity transformation, which can be explained by a change of the resonance condition with variation of the laser energy. Thus, we concluded that PSE molecules create nanohybrids with SWNTs, which ensures the further enzyme immobilization. As the RR spectrum of an SWNT:PSE:GOX film does not essentially differ from SWNT:PSE ones, this indicates that the molecular interface (PSE) isolates the enzyme from nanotubes strongly enough. Our studies on the conductive properties of a single walled carbon nanotube network sprayed onto a quartz substrate from a solution of nanotubes in dichlorobenzene demonstrated that the I(U) dependence has nonlinear character. Most likely, the nonlinearity is related to Schottky barriers, which originate on the contact between nanotubes and the gold electrode, as well as between nanotubes with different conductivities. The deposition of bioorganic compounds (PSE and GOX) on the carbon nanotube network is accompanied by a decrease of their conductivity. Most probably, such a decrease is caused by adsorbed PSE molecules, which induce the appearance of scattering centers for charge carriers on the nanotube surface. The following GOX adsorption has practically no effect on the conductivity of the nanotube network that evidences the reliable isolation of the nanotube surface from the enzyme by means of the molecular

  18. Regulation of the NADPH Oxidase RBOHD During Plant Immunity.

    Science.gov (United States)

    Kadota, Yasuhiro; Shirasu, Ken; Zipfel, Cyril

    2015-08-01

    Pathogen recognition induces the production of reactive oxygen species (ROS) by NADPH oxidases in both plants and animals. ROS have direct antimicrobial properties, but also serve as signaling molecules to activate further immune outputs. However, ROS production has to be tightly controlled to avoid detrimental effects on host cells, but yet must be produced in the right amount, at the right place and at the right time upon pathogen perception. Plant NADPH oxidases belong to the respiratory burst oxidase homolog (RBOH) family, which contains 10 members in the model plant Arabidopsis thaliana. The perception of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs) leads to a rapid, specific and strong production of ROS, which is dependent on RBOHD. RBOHD is mainly controlled by Ca(2+) via direct binding to EF-hand motifs and phosphorylation by Ca(2+)-dependent protein kinases. Recent studies have, however, revealed a critical role for a Ca(2+)-independent regulation of RBOHD. The plasma membrane-associated cytoplasmic kinase BIK1 (BOTRYTIS-INDUCED KINASE1), which is a direct substrate of the PRR complex, directly interacts with and phosphorylates RBOHD upon PAMP perception. Impairment of these phosphorylation events completely abolishes the function of RBOHD in immunity. These results suggest that RBOHD activity is tightly controlled by multilayered regulations. In this review, we summarize recent advances in our understanding of the regulatory mechanisms controlling RBOHD activation. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  19. Electroconvulsive therapy in patients taking monoamine oxidase inhibitors.

    Science.gov (United States)

    Dolenc, Tamara J; Habl, Samar S; Barnes, Roxann D; Rasmussen, Keith G

    2004-12-01

    Concerns have been expressed regarding the use of general anesthesia for electroconvulsive therapy (ECT) in patients taking monoamine oxidase inhibitors (MAOIs). We review the published literature and present 4 new cases and conclude that there is no evidence of a dangerous interaction between ECT and MAOI use. In general, a cautious approach would be to discontinue MAOIs before ECT if the medication has not been helpful; however, there is no need for a washout interval before starting ECT. Furthermore, if there is otherwise a reason for continuing the MAOI, it can be continued during index ECT or initiated during maintenance ECT.

  20. Lysyl Oxidase, a Targetable Secreted Molecule Involved in Cancer Metastasis

    DEFF Research Database (Denmark)

    Cox, Thomas Robert; Gartland, Alison; Erler, Janine T

    2016-01-01

    to improve the tools available in our arsenal against this disease, both in terms of treatment, but also prevention. Recently, we showed that hypoxic induction of the extracellular matrix modifying enzyme lysyl oxidase (LOX) correlates with metastatic dissemination to the bone in estrogen receptor negative...... of this enzyme as a therapeutic target for metastatic breast cancer. Our work is the latest in an emerging body of work supporting the targeting of LOX and calls for greater efforts in developing therapeutics against this extracellular secreted factor in the prevention of cancer progression across multiple solid...

  1. Plasma amine oxidase activities in Norrie disease patients with an X-chromosomal deletion affecting monoamine oxidase.

    Science.gov (United States)

    Murphy, D L; Sims, K B; Karoum, F; Garrick, N A; de la Chapelle, A; Sankila, E M; Norio, R; Breakefield, X O

    1991-01-01

    Two individuals with an X-chromosomal deletion were recently found to lack the genes encoding monoamine oxidase type A (MAO-A) and MAO-B. This abnormality was associated with almost total (90%) reductions in the oxidatively deaminated urinary metabolites of the MAO-A substrate, norepinephrine, and with marked (100-fold) increases in an MAO-B substrate, phenylethylamine, confirming systemic functional consequences of the genetic enzyme deficiency. However, urinary concentrations of the deaminated metabolites of dopamine and serotonin (5-HT) were essentially normal. To investigate other deaminating systems besides MAO-A and MAO-B that might produce these metabolites of dopamine and 5-HT, we examined plasma amine oxidase (AO) activity in these two patients and two additional patients with the same X-chromosomal deletion. Normal plasma AO activity was found in all four Norrie disease-deletion patients, in four patients with classic Norrie disease without a chromosomal deletion, and in family members of patients from both groups. Marked plasma amine metabolite abnormalities and essentially absent platelet MAO-B activity were found in all four Norrie disease-deletion patients, but in none of the other subjects in the two comparison groups. These results indicate that plasma AO is encoded by gene(s) independent of those for MAO-A and MAO-B, and raise the possibility that plasma AO, and perhaps the closely related tissue AO, benzylamine oxidase, as well as other atypical AOs or MAOs encoded independently from MAO-A and MAO-B may contribute to the oxidative deamination of dopamine and 5-HT in humans.

  2. Hofmeister effects on the glucose oxidase hydrogel-modified electrode

    International Nuclear Information System (INIS)

    Suzuki, Aimi; Tsujimura, Seiya

    2016-01-01

    We describe the consistent effect of salts in the electrolyte solution on glucose oxidation current production in the redox hydrogel-modified electrode containing glucose oxidase as an electrocatalyst and Os complex mediator. The ions affect not only on the electron transfer between the enzyme and the Os complex, but also on the hydrogel structure. This study found that the degree of the effect can be characterized by Hofmeister series. The relative decrease in oxidization current is the lowest in the middle of the Hofmeister series, and increases monotonically on either side. An increase of ionic strength inhibits the electron transfer from the active site of glucose oxidase to Os complex. In addition to this, the kosmotropic anions, which are strongly hydrated, caused hydrogel deswelling (shrinking). The more chaotropic an ion is, the more it adsorbs to uncharged parts of polymer/enzyme with dispersion force, and the swelling of the hydrogel decreases the catalytic current. This study impacts the design of hydrogel electrode and selection of electrolyte ions for bioelectronic applications.

  3. Cytochrome oxidase assembly does not require catalytically active cytochrome C.

    Science.gov (United States)

    Barrientos, Antoni; Pierre, Danielle; Lee, Johnson; Tzagoloff, Alexander

    2003-03-14

    Cytochrome c oxidase (COX), the terminal enzyme of the mitochondrial respiratory chain, catalyzes the transfer of electrons from reduced cytochrome c to molecular oxygen. COX assembly requires the coming together of nuclear- and mitochondrial-encoded subunits and the assistance of a large number of nuclear gene products acting at different stages of maturation of the enzyme. In Saccharomyces cerevisiae, expression of cytochrome c, encoded by CYC1 and CYC7, is required not only for electron transfer but also for COX assembly through a still unknown mechanism. We have attempted to distinguish between a functional and structural requirement of cytochrome c in COX assembly. A cyc1/cyc7 double null mutant strain was transformed with the cyc1-166 mutant gene (Schweingruber, M. E., Stewart, J. W., and Sherman, F. (1979) J. Biol. Chem. 254, 4132-4143) that expresses stable but catalytically inactive iso-1-cytochrome c. The COX content of the cyc1/cyc7 double mutant strain harboring non-functional iso-1-cytochrome c has been characterized spectrally, functionally, and immunochemically. The results of these studies demonstrate that cytochrome c plays a structural rather than functional role in assembly of cytochrome c oxidase. In addition to its requirement for COX assembly, cytochrome c also affects turnover of the enzyme. Mutants containing wild type apocytochrome c in mitochondria lack COX, suggesting that only the folded and mature protein is able to promote COX assembly.

  4. Oxidase catalysis via aerobically generated hypervalent iodine intermediates

    Science.gov (United States)

    Maity, Asim; Hyun, Sung-Min; Powers, David C.

    2018-02-01

    The development of sustainable oxidation chemistry demands strategies to harness O2 as a terminal oxidant. Oxidase catalysis, in which O2 serves as a chemical oxidant without necessitating incorporation of oxygen into reaction products, would allow diverse substrate functionalization chemistry to be coupled to O2 reduction. Direct O2 utilization suffers from intrinsic challenges imposed by the triplet ground state of O2 and the disparate electron inventories of four-electron O2 reduction and two-electron substrate oxidation. Here, we generate hypervalent iodine reagents—a broadly useful class of selective two-electron oxidants—from O2. This is achieved by intercepting reactive intermediates of aldehyde autoxidation to aerobically generate hypervalent iodine reagents for a broad array of substrate oxidation reactions. The use of aryl iodides as mediators of aerobic oxidation underpins an oxidase catalysis platform that couples substrate oxidation directly to O2 reduction. We anticipate that aerobically generated hypervalent iodine reagents will expand the scope of aerobic oxidation chemistry in chemical synthesis.

  5. 2-acetylphenol analogs as potent reversible monoamine oxidase inhibitors

    Directory of Open Access Journals (Sweden)

    Legoabe LJ

    2015-07-01

    Full Text Available Lesetja J Legoabe,1 Anél Petzer,1 Jacobus P Petzer1,21Centre of Excellence for Pharmaceutical Sciences, 2Department of Pharmaceutical Chemistry, School of Pharmacy, North-West University, Potchefstroom, South AfricaAbstract: Based on a previous report that substituted 2-acetylphenols may be promising leads for the design of novel monoamine oxidase (MAO inhibitors, a series of C5-substituted 2-acetylphenol analogs (15 and related compounds (two were synthesized and evaluated as inhibitors of human MAO-A and MAO-B. Generally, the study compounds exhibited inhibitory activities against both MAO-A and MAO-B, with selectivity for the B isoform. Among the compounds evaluated, seven compounds exhibited IC50 values <0.01 µM for MAO-B inhibition, with the most selective compound being 17,000-fold selective for MAO-B over the MAO-A isoform. Analyses of the structure–activity relationships for MAO inhibition show that substitution on the C5 position of the 2-acetylphenol moiety is a requirement for MAO-B inhibition, and the benzyloxy substituent is particularly favorable in this regard. This study concludes that C5-substituted 2-acetylphenol analogs are potent and selective MAO-B inhibitors, appropriate for the design of therapies for neurodegenerative disorders such as Parkinson’s disease.Keywords: monoamine oxidase, MAO, inhibition, 2-acetylphenol, structure–activity relationship

  6. Fabrication of Amperometric Glucose Sensor Using Glucose Oxidase-Cellulose Nanofiber Aqueous Solution.

    Science.gov (United States)

    Yasuzawa, Mikito; Omura, Yuya; Hiura, Kentaro; Li, Jiang; Fuchiwaki, Yusuke; Tanaka, Masato

    2015-01-01

    Cellulose nanofiber aqueous solution, which remained virtually transparent for more than one week, was prepared by using the clear upper layer of diluted cellulose nanofiber solution produced by wet jet milling. Glucose oxidase (GOx) was easily dissolved in this solution and GOx-immobilized electrode was easily fabricated by simple repetitious drops of GOx-cellulose solution on the surface of a platinum-iridium electrode. Glucose sensor properties of the obtained electrodes were examined in phosphate buffer solution of pH 7.4 at 40°C. The obtained electrode provided a glucose sensor response with significantly high response speed and good linear relationship between glucose concentration and response current. After an initial decrease of response sensitivity for a few days, relatively constant sensitivity was obtained for about 20 days. Nevertheless, the influence of electroactive compounds such as ascorbic acid, uric acid and acetoaminophen were not negletable.

  7. Glucose Oxidase Biosensor Modeling and Predictors Optimization by Machine Learning Methods.

    Science.gov (United States)

    Gonzalez-Navarro, Felix F; Stilianova-Stoytcheva, Margarita; Renteria-Gutierrez, Livier; Belanche-Muñoz, Lluís A; Flores-Rios, Brenda L; Ibarra-Esquer, Jorge E

    2016-10-26

    Biosensors are small analytical devices incorporating a biological recognition element and a physico-chemical transducer to convert a biological signal into an electrical reading. Nowadays, their technological appeal resides in their fast performance, high sensitivity and continuous measuring capabilities; however, a full understanding is still under research. This paper aims to contribute to this growing field of biotechnology, with a focus on Glucose-Oxidase Biosensor (GOB) modeling through statistical learning methods from a regression perspective. We model the amperometric response of a GOB with dependent variables under different conditions, such as temperature, benzoquinone, pH and glucose concentrations, by means of several machine learning algorithms. Since the sensitivity of a GOB response is strongly related to these dependent variables, their interactions should be optimized to maximize the output signal, for which a genetic algorithm and simulated annealing are used. We report a model that shows a good generalization error and is consistent with the optimization.

  8. Cholesterol oxidase interference on the emergence and viability of cotton boll weevil larvae

    Directory of Open Access Journals (Sweden)

    Santos Roseane Cavalcanti

    2002-01-01

    Full Text Available The aim of this work was to evaluate the influence of the enzyme cholesterol oxidase (Coase on emergence and viability of larvae of the cotton boll weevil (Anthonomus grandis Boheman, 1843. A series of bioassays was performed with eggs and neonate larvae exposed to different enzyme concentrations in artificial diet. Larval survival was affected at all enzyme concentrations tested, and the six-day LD50 was 53 mug/mL (CI 95%: 43-59. Coase also interfered with hatching of larvae after eggs were floated for 15 min in Coase solution at different concentrations. Observations at the light and electronic microscopic level of midguts from larvae fed on artificial diet containing 53 mug/mL of Coase and collected at six days revealed highly vacuolated regions in the epithelial cells as well as partial degradation of the basal membrane and microvilli.

  9. Kinetic study on the inhibition of xanthine oxidase by acylated derivatives of flavonoids synthesised enzymatically.

    Science.gov (United States)

    de Araújo, Maria Elisa Melo Branco; Franco, Yollanda Edwirges Moreira; Alberto, Thiago Grando; Messias, Marcia Cristina Fernandes; Leme, Camila Wielewski; Sawaya, Alexandra Christine Helena Frankland; Carvalho, Patricia de Oliveira

    2017-12-01

    Studies have reported that flavonoids inhibit xanthine oxidase (XO) activity; however, poor solubility and stability in lipophilic media limit their bioavailability and applications. This study evaluated the kinetic parameters of XO inhibition and partition coefficients of flavonoid esters biosynthesised from hesperidin, naringin, and rutin via enzymatic acylation with hexanoic, octanoic, decanoic, lauric, and oleic acids catalysed by Candida antarctica lipase B (CALB). Quantitative determination by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) showed higher conversion yields (%) for naringin and rutin esters using acyl donors with 8C and 10C. Rutin decanoate had higher partition coefficients (0.95), and naringin octanoate and naringin decanoate showed greater inhibitory effects on XO (IC 50 of 110.35 and 117.51 μM, respectively). Kinetic analysis showed significant differences (p flavonoids before and after acylation regarding K m values, whereas the values for V max were the same, implying the competitive nature of XO inhibition.

  10. Evolution of multicopper oxidase genes in coprophilous and non-coprophilous members of the order sordariales.

    Science.gov (United States)

    Pöggeler, Stefanie

    2011-04-01

    Multicopper oxidases (MCO) catalyze the biological oxidation of various aromatic substrates and have been identified in plants, insects, bacteria, and wood rotting fungi. In nature, they are involved in biodegradation of biopolymers such as lignin and humic compounds, but have also been tested for various industrial applications. In fungi, MCOs have been shown to play important roles during their life cycles, such as in fruiting body formation, pigment formation and pathogenicity. Coprophilous fungi, which grow on the dung of herbivores, appear to encode an unexpectedly high number of enzymes capable of at least partly degrading lignin. This study compared the MCO-coding capacity of the coprophilous filamentous ascomycetes Podospora anserina and Sordaria macrospora with closely related non-coprophilous members of the order Sordariales. An increase of MCO genes in coprophilic members of the Sordariales most probably occurred by gene duplication and horizontal gene transfer events.

  11. Probing Structural and Catalytic Characteristics of Galactose Oxidase Confined in Nanoscale Chemical Environments

    DEFF Research Database (Denmark)

    Ikemoto, Hideki; Mossin, Susanne; Ulstrup, Jens

    2014-01-01

    Galactose oxidase (GAOX) is a special metalloenzyme in terms of its active site structure and catalytic mechanisms. This work reports a study where the enzyme confined in a nanoscale chemical environment provided by mesoporous silicas (MPS) is probed. Two types of MPS, i.e. SBA-15 and MCF, were...... synthesized and used to accommodate GAOX. SBA-15-ROD is rod-shaped particles with periodically ordered nanopores (9.5 nm), while MCF has a mesocellular foam-like structure with randomly distributed pores (23 nm) interconnected by smaller windows (8.8 nm). GAOX is non-covalently confined in SBA-15- ROD, while...... it is covalently immobilized in MCF. Relatively high loadings in the range of 50–60 mg g1 are achieved. Electron spin resonance (ESR) spectroscopy is used to probe the active site structures of the enzyme. The similar ESR spectra observed for GAOX in the free and immobilized states support that the electronic...

  12. Glucose Oxidase Biosensor Modeling and Predictors Optimization by Machine Learning Methods

    Directory of Open Access Journals (Sweden)

    Felix F. Gonzalez-Navarro

    2016-10-01

    Full Text Available Biosensors are small analytical devices incorporating a biological recognition element and a physico-chemical transducer to convert a biological signal into an electrical reading. Nowadays, their technological appeal resides in their fast performance, high sensitivity and continuous measuring capabilities; however, a full understanding is still under research. This paper aims to contribute to this growing field of biotechnology, with a focus on Glucose-Oxidase Biosensor (GOB modeling through statistical learning methods from a regression perspective. We model the amperometric response of a GOB with dependent variables under different conditions, such as temperature, benzoquinone, pH and glucose concentrations, by means of several machine learning algorithms. Since the sensitivity of a GOB response is strongly related to these dependent variables, their interactions should be optimized to maximize the output signal, for which a genetic algorithm and simulated annealing are used. We report a model that shows a good generalization error and is consistent with the optimization.

  13. Biodegradation of phenolic compounds with oxidases from sorghum and non-defined mixed bacterium media

    International Nuclear Information System (INIS)

    Obame, C. E. L.; Savadogo, P. W.; Mamoudou, D. H.; Dembele, R. H.; Traore, A. S.

    2009-01-01

    The biodegradation of the phenolic compounds is performed using oxidative enzymes, e. g. polyphenol oxidases (PPOs) and peroxidases (POXs). These oxidases displaying a wide spectrum for the oxidation of phenolic compounds were isolated either from sorghum or mixed bacteria. Spectrophotometric methods were used to assess the monophenolase and diphenolase activities of PPOs as well as the hydrogen-dependant oxidation of POXs. (Author)

  14. Study on the preparation of immobilized glucose oxidase membrane and its application in clinic analysis

    International Nuclear Information System (INIS)

    Yu Ye; Cao Jin; Su Zongxian; Chen Zixiong

    1990-01-01

    The paper deals with the preparation of immobilized glucose oxidase membrane by using two steps irradiation (irradiation gratfting, irradiation entrapping). Some properties of membrane were discussed. The immobilized glucose oxidase membrane with oxygen electrode and oxygen analyser can be satisfied with the clinic analysis for the determination of serum glucose

  15. Switching an O2 sensitive glucose oxidase bioelectrode into an almost insensitive one by cofactor redesign.

    Science.gov (United States)

    Tremey, Emilie; Suraniti, Emmanuel; Courjean, Olivier; Gounel, Sébastien; Stines-Chaumeil, Claire; Louerat, Frédéric; Mano, Nicolas

    2014-06-04

    In the 5-8 mM glucose concentration range, of particular interest for diabetes management, glucose oxidase bioelectrodes are O2 dependent, which decrease their efficiencies. By replacing the natural cofactor of glucose oxidase, we succeeded in turning an O2 sensitive bioelectrode into an almost insensitive one.

  16. Hydroxychavicol: a potent xanthine oxidase inhibitor obtained from the leaves of betel, Piper betle.

    Science.gov (United States)

    Murata, Kazuya; Nakao, Kikuyo; Hirata, Noriko; Namba, Kensuke; Nomi, Takao; Kitamura, Yoshihisa; Moriyama, Kenzo; Shintani, Takahiro; Iinuma, Munekazu; Matsuda, Hideaki

    2009-07-01

    The screening of Piperaceous plants for xanthine oxidase inhibitory activity revealed that the extract of the leaves of Piper betle possesses potent activity. Activity-guided purification led us to obtain hydroxychavicol as an active principle. Hydroxychavicol is a more potent xanthine oxidase inhibitor than allopurinol, which is clinically used for the treatment of hyperuricemia.

  17. Analysis of cellulase and polyphenol oxidase production by southern pine beetle associated fungi

    Science.gov (United States)

    Abduvali Valiev; Zumrut B. Ogel; Dier D. Klepzig

    2009-01-01

    In this study, the production of extracellular enzymes by fungi associated with southern pine beetle was investigated for the first time. Cellulase and polyphenol oxidase production were analyzed for three beetle associated fungi. Only the mutualistic symbiont Entomocorticium sp. A was found to produce cellulases and polyphenol oxidase....

  18. Biocatalytic potential of laccase-like multicopper oxidases from Aspergillus niger

    NARCIS (Netherlands)

    Tamayo Ramos, J.A.; Berkel, van W.J.H.; Graaff, de L.H.

    2012-01-01

    BACKGROUND: Laccase-like multicopper oxidases have been reported in several Aspergillus species but they remain uncharacterized. The biocatalytic potential of the Aspergillus niger fungal pigment multicopper oxidases McoA and McoB and ascomycete laccase McoG was investigated. RESULTS: The

  19. Purification, characterization and decolorization of bilirubin oxidase from Myrothecium verrucaria 3.2190

    Science.gov (United States)

    Myrothecium verrucaria 3.2190 is a nonligninolytic fungus that produces bilirubin oxidase. Both Myrothecium verrucaria and the extracellular bilirubin oxidase were tested for their ability to decolorize indigo carmine. The biosorption and biodegradation of the dye were detected during the process of...

  20. Biodegradation of phenolic compounds with oxidases from sorghum and non-defined mixed bacterium media

    Energy Technology Data Exchange (ETDEWEB)

    Obame, C. E. L.; Savadogo, P. W.; Mamoudou, D. H.; Dembele, R. H.; Traore, A. S.

    2009-07-01

    The biodegradation of the phenolic compounds is performed using oxidative enzymes, e. g. polyphenol oxidases (PPOs) and peroxidases (POXs). These oxidases displaying a wide spectrum for the oxidation of phenolic compounds were isolated either from sorghum or mixed bacteria. Spectrophotometric methods were used to assess the monophenolase and diphenolase activities of PPOs as well as the hydrogen-dependant oxidation of POXs. (Author)

  1. Bacillus calmette-guerin infection in NADPH oxidase deficiency: defective mycobacterial sequestration and granuloma formation.

    Directory of Open Access Journals (Sweden)

    Christine Deffert

    2014-09-01

    Full Text Available Patients with chronic granulomatous disease (CGD lack generation of reactive oxygen species (ROS through the phagocyte NADPH oxidase NOX2. CGD is an immune deficiency that leads to frequent infections with certain pathogens; this is well documented for S. aureus and A. fumigatus, but less clear for mycobacteria. We therefore performed an extensive literature search which yielded 297 cases of CGD patients with mycobacterial infections; M. bovis BCG was most commonly described (74%. The relationship between NOX2 deficiency and BCG infection however has never been studied in a mouse model. We therefore investigated BCG infection in three different mouse models of CGD: Ncf1 mutants in two different genetic backgrounds and Cybb knock-out mice. In addition, we investigated a macrophage-specific rescue (transgenic expression of Ncf1 under the control of the CD68 promoter. Wild-type mice did not develop severe disease upon BCG injection. In contrast, all three types of CGD mice were highly susceptible to BCG, as witnessed by a severe weight loss, development of hemorrhagic pneumonia, and a high mortality (∼ 50%. Rescue of NOX2 activity in macrophages restored BCG resistance, similar as seen in wild-type mice. Granulomas from mycobacteria-infected wild-type mice generated ROS, while granulomas from CGD mice did not. Bacterial load in CGD mice was only moderately increased, suggesting that it was not crucial for the observed phenotype. CGD mice responded with massively enhanced cytokine release (TNF-α, IFN-γ, IL-17 and IL-12 early after BCG infection, which might account for severity of the disease. Finally, in wild-type mice, macrophages formed clusters and restricted mycobacteria to granulomas, while macrophages and mycobacteria were diffusely distributed in lung tissue from CGD mice. Our results demonstrate that lack of the NADPH oxidase leads to a markedly increased severity of BCG infection through mechanisms including increased cytokine

  2. Lysyl oxidase overexpression accelerates cardiac remodeling and aggravates angiotensin II-induced hypertrophy.

    Science.gov (United States)

    Galán, María; Varona, Saray; Guadall, Anna; Orriols, Mar; Navas, Miquel; Aguiló, Silvia; de Diego, Alicia; Navarro, María A; García-Dorado, David; Rodríguez-Sinovas, Antonio; Martínez-González, José; Rodriguez, Cristina

    2017-09-01

    Lysyl oxidase (LOX) controls matrix remodeling, a key process that underlies cardiovascular diseases and heart failure; however, a lack of suitable animal models has limited our knowledge with regard to the contribution of LOX to cardiac dysfunction. Here, we assessed the impact of LOX overexpression on ventricular function and cardiac hypertrophy in a transgenic LOX (TgLOX) mouse model with a strong cardiac expression of human LOX. TgLOX mice exhibited high expression of the transgene in cardiomyocytes and cardiofibroblasts, which are associated with enhanced LOX activity and H 2 O 2 production and with cardiofibroblast reprogramming. LOX overexpression promoted an age-associated concentric remodeling of the left ventricle and impaired diastolic function. Furthermore, LOX transgenesis aggravated angiotensin II (Ang II)-induced cardiac hypertrophy and dysfunction, which triggered a greater fibrotic response that was characterized by stronger collagen deposition and cross-linking and high expression of fibrotic markers. In addition, LOX transgenesis increased the Ang II-induced myocardial inflammatory infiltrate, exacerbated expression of proinflammatory markers, and decreased that of cardioprotective factors. Mechanistically, LOX overexpression enhanced oxidative stress and potentiated the Ang II-mediated cardiac activation of p38 MAPK while reducing AMPK activation. Our findings suggest that LOX induces an age-dependent disturbance of diastolic function and aggravates Ang II-induced hypertrophy, which provides novel insights into the role of LOX in cardiac performance.-Galán, M., Varona, S., Guadall, A., Orriols, M., Navas, M., Aguiló, S., de Diego, A., Navarro, M. A., García-Dorado, D., Rodríguez-Sinovas, A., Martínez-González, J., Rodriguez, C. Lysyl oxidase overexpression accelerates cardiac remodeling and aggravates angiotensin II-induced hypertrophy. © FASEB.

  3. Redox-flexible NADH oxidase biosensor: A platform for various dehydrogenase bioassays and biosensors

    International Nuclear Information System (INIS)

    Serban, Simona; El Murr, Nabil

    2006-01-01

    A generic amperometric bioassay based on the enzymatic oxidation catalysed by the stable NADH oxidase (NAox) from Thermus thermophilus has been developed for NADH measurements. The NAox uses O 2 as its natural electron acceptor and produces H 2 O 2 in a two-electron process. Electrochemical and spectrophotometric experiments showed that the NAox used in this work, presents a very good activity towards its substrate and, in contrary to previously mentioned NADH oxidases, does not require the addition of any exogenous flavin cofactor neither to promote nor to maintain its activity. In addition, the NAox used also works with artificial electron acceptors like ferrocene derivatives. O 2 was successfully replaced by redox mediators such as hydroxymethyl ferrocene (FcCH 2 OH) for the regeneration of the active enzyme. Combining the NAox with the mediator and the horseradish peroxidase we developed an original, high sensitive 'redox-flexible' NADH amperometric bioassay working in a large window of applied potentials in both oxidation and reduction modes. The biosensor has a continuous and complementary linearity range permitting to measure NADH concentrations starting from 5 x 10 -6 M in reduction until 2 x 10 3 M in oxidation. This redox-flexibility allows choosing the applied potential in order to avoid electrochemical interferences. The association of the 'redox-flexible' concept with NADH dependent enzymes opens a novel strategy for dehydrogenases based bioassays and biosensors. The great number of dehydrogenases available makes the concept applicable for numerous substrates to analyse. Moreover it allows the development of a wide range of biosensors on the basis of a generic platform. This gives several advantages over the previous manufacturing techniques and offers a general and flexible scheme for the fabrication of biosensors presenting high sensitivities, wide calibration ranges and less affected by electrochemical interferences

  4. Antiglycation, radical scavenging, and semicarbazide-sensitive amine oxidase inhibitory activities of acetohydroxamic acid in vitro

    Directory of Open Access Journals (Sweden)

    Liu YH

    2017-07-01

    Full Text Available Yuh-Hwa Liu,1,2,* Yeh-Lin Lu,3,* Der-Zen Liu,4 Wen-Chi Hou5 1Division of Gastroenterology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan; 2Department of General Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; 3Department of Pharmacy, Taipei Medical University, Taipei, Taiwan; 4Graduate Institute of Biomedical Materials and Tissue Engineering, Taipei Medical University, Taipei, Taiwan; 5Graduate Institute of Pharmacognosy, Taipei Medical University, Taipei, Taiwan *These authors contributed equally to this work Abstract: Advanced glycation endproducts (AGEs can promote intracellular reactive oxygen species production, and the levels of AGEs are highly correlated with cardiovascular disease and diabetes complications. Acetohydroxamic acid (acetH is a bacterial urease inhibitor drug used to treat kidney stones and infections in the urinary tract, and hydroxyurea (HU is a drug used for antineoplasm and sickle cell diseases. Both acetH and HU are hydroxamic acid derivatives. It was found that acetH and HU at 2.5 or 5 mM showed anti-AGE formation by lowering the AGEs’ fluorescent intensities and Nε-(carboxymethyllysine formation in bovine serum albumin/galactose models, and both showed better and significant differences (P<0.05 compared to the positive control of aminoguanidine. Regarding radical scavenging activities, the half-inhibition concentrations (IC50 of acetH against α,α-diphenyl-β-picrylhydrazyl radical and hydroxyl radical were 34.86 and 104.42 µM, respectively. The IC50 of acetH against semicarbazide-sensitive amine oxidase was 10.56 µM, and acetH showed noncompetitive inhibition respective to the substrates (benzylamine. The antiglycation, antioxidant, and semicarbazide-sensitive amine oxidase inhibitory activities of acetH prove that it has the potential for treating cardiovascular disease and diabetes complications and it needs further investigation in animal models. Keywords: acetH, AGEs, Nε

  5. Characterisation of recombinant pyranose oxidase from the cultivated mycorrhizal basidiomycete Lyophyllum shimeji (hon-shimeji

    Directory of Open Access Journals (Sweden)

    Yamabhai Montarop

    2010-07-01

    Full Text Available Abstract Background The flavin-dependent enzyme pyranose 2-oxidase (P2Ox has gained increased attention during the last years because of a number of attractive applications for this enzyme. P2Ox is a unique biocatalyst with high potential for biotransformations of carbohydrates and in synthetic carbohydrate chemistry. Recently, it was shown that P2Ox is useful as bioelement in biofuel cells, replacing glucose oxidase (GOx, which traditionally is used in these applications. P2Ox offers several advantages over GOx for this application, e.g., its much broader substrate specificity. Because of this renewed interest in P2Ox, knowledge on novel pyranose oxidases isolated from organisms other than white-rot fungi, which represent the traditional source of this enzyme, is of importance, as these novel enzymes might differ in their biochemical and physical properties. Results We isolated and over-expressed the p2ox gene encoding P2Ox from the ectomycorrhizal fungus Lyophyllum shimeji. The p2ox cDNA was inserted into the bacterial expression vector pET21a(+ and successfully expressed in E. coli Rosetta 2. We obtained active, flavinylated recombinant P2Ox in yields of approximately 130 mg per L of medium. The enzyme was purified by a two-step procedure based on anion exchange chromatography and preparative native PAGE, yielding an apparently homogenous enzyme preparation with a specific activity of 1.92 U/mg (using glucose and air oxygen as the substrates. Recombinant P2Ox from L. shimeji was characterized in some detail with respect to its physical and catalytic properties, and compared to the well-characterised enzymes from Phanerochaete chrysosporium and Trametes multicolor. Conclusion L. shimeji P2Ox shows properties that are comparable to those of P2Ox from white-rot fungal origin, and is in general characterised by lower Km and kcat values both for electron donor (sugar as well as electron acceptor (ferrocenium ion, 1,4-benzoquinone, 2

  6. Expression and Chloroplast Targeting of Cholesterol Oxidase in Transgenic Tobacco Plants

    Science.gov (United States)

    Corbin, David R.; Grebenok, Robert J.; Ohnmeiss, Thomas E.; Greenplate, John T.; Purcell, John P.

    2001-01-01

    Cholesterol oxidase represents a novel type of insecticidal protein with potent activity against the cotton boll weevil (Anthonomus grandis grandis Boheman). We transformed tobacco (Nicotiana tabacum) plants with the cholesterol oxidase choM gene and expressed cytosolic and chloroplast-targeted versions of the ChoM protein. Transgenic leaf tissues expressing cholesterol oxidase exerted insecticidal activity against boll weevil larvae. Our results indicate that cholesterol oxidase can metabolize phytosterols in vivo when produced cytosolically or when targeted to chloroplasts. The transgenic plants exhibiting cytosolic expression accumulated low levels of saturated sterols known as stanols, and displayed severe developmental aberrations. In contrast, the transgenic plants expressing chloroplast-targeted cholesterol oxidase maintained a greater accumulation of stanols, and appeared phenotypically and developmentally normal. These results are discussed within the context of plant sterol distribution and metabolism. PMID:11457962

  7. Amine oxidase from lentil seedlings: energetic domains and effect of temperature on activity.

    Science.gov (United States)

    Moosavi-Nejad, S Z; Rezaei-Tavirani, M; Padiglia, A; Floris, G; Moosavi-Movahedi, A A

    2001-07-01

    Copper/TPQ amine oxidases from mammalian and plant sources have shown many differences in substrate specificity and molecular properties. In this work the activity of lentil seedling amine oxidase was followed at various temperatures in 100 mM potassium phosphate buffer, pH 7, using benzylamine as substrate. The discontinuous Arrhenius plot of lentil amine oxidase showed two distinct phases with a jump between them. Thermal denaturation of the enzyme, using differential scanning calorimetry under the same experimental conditions, showed a transition at the same temperature ranges in the absence of substrate, indicating the occurrence of conformational changes, with an enthalpy change of about 175.9 kJ/mole. The temperature-induced changes of the activity of lentil amine oxidase are compared with those of bovine serum amine oxidase (taken from the literature).

  8. Functional expression of amine oxidase from Aspergillus niger (AO-I) in Saccharomyces cerevisiae.

    Science.gov (United States)

    Kolaríková, Katerina; Galuszka, Petr; Sedlárová, Iva; Sebela, Marek; Frébort, Ivo

    2009-01-01

    The aim of this work was to prepare recombinant amine oxidase from Aspergillus niger after overexpressing in yeast. The yeast expression vector pDR197 that includes a constitutive PMA1 promoter was used for the expression in Saccharomyces cerevisiae. Recombinant amine oxidase was extracted from the growth medium of the yeast, purified to homogeneity and identified by activity assay and MALDI-TOF peptide mass fingerprinting. Similarity search in the newly published A. niger genome identified six genes coding for copper amine oxidase, two of them corresponding to the previously described enzymes AO-I a methylamine oxidase and three other genes coding for FAD amine oxidases. Thus, A. niger possesses an enormous metabolic gear to grow on amine compounds and thus support its saprophytic lifestyle.

  9. [Experimental rationale for the parameters of a rapid method for oxidase activity determination].

    Science.gov (United States)

    Butorina, N N

    2010-01-01

    Experimental rationale is provided for the parameters of a rapid (1-2-min) test to concurrently determine the oxidase activity of all bacteria grown on the membrane filter after water filtration. Oxidase reagents that are the aqueous solutions of tetramethyl-p-phenylenediamine dihydrochloride and demethyl-p-phenylenediamine dihydrochloride have been first ascertained to exert no effect on the viability and enzymatic activity of bacteria after one-hour contact. An algorithm has been improved for the rapid oxidase activity test: the allowable time for bacteria to contact oxidase reagents and procedures for minimizing the effect on bacterial biochemical activity following the contact. An accelerated method based on lactose medium with tergitol 7 and Endo agar has been devised to determine coliform bacteria, by applying the rapid oxidase test: the time of a final response is 18-24 hours. The method has been included into GOST 52426-2005.

  10. A Biocatalytic One-Pot Approach for the Preparation of Lignin Oligomers Using an Oxidase/Peroxidase Cascade Enzyme System

    NARCIS (Netherlands)

    Habib, Mohamed H. M.; Deuss, Peter J.; Loncar, Nikola; Trajkovic, Milos; Fraaije, Marco W.

    2017-01-01

    Synthetic lignin was prepared biocatalytically in a one-pot, two-step reaction using an oxidase/peroxidase cascade enzyme system. Using eugenol in combination with eugenol oxidase and a peroxidase, lignin-like material was produced. The cascade reaction takes advantage of the ability of the oxidase

  11. Memristive Properties of Thin Film Cuprous Oxide

    Science.gov (United States)

    2011-03-01

    changes in the force sensed by the piezo electric crystal. ..................... 9 2. Schematic of the principles of Scanning Tunneling Microscopy (STM...developed the concept of the memristor in the 1970s. The three fundamental two-terminal elements in circuits, namely resistors , conductors, and...off the backside of the cantilever and changes in the force sensed by the piezo electric crystal. The AFM is a powerful tool for studying

  12. Preparation and characterization of cuprous iodide nanoparticles

    International Nuclear Information System (INIS)

    Hong Tao Li; Li Xia Gu

    2007-01-01

    A new technique for the preparation of CuI nanoparticles from CuSO 4 and KI ethanol solutions has been developed. Preparation conditions were optimized through a series of experiments. Under these conditions, the yield of CuI reached 95.39%. The product was characterized and the reaction kinetics was studied. The results show that the product takes a roughly spherical shape with an average particle size of less then 50 nm. The activation energy of the formation of CuI is found to be E a = 0.58 x 10 2 kJ/mol, and the preexponential factor in the Arrhenius equation is k 0 = 7.43 x 10 16 mol/(l s) [ru

  13. Evaluation of Fluorine-18-Labeled α1(I-N-Telopeptide Analogs as Substrate-Based Radiotracers for PET Imaging of Melanoma-Associated Lysyl Oxidase

    Directory of Open Access Journals (Sweden)

    Manuela Kuchar

    2018-04-01

    Full Text Available Accumulating evidence suggests an unequivocal role of lysyl oxidases as key players of tumor progression and metastasis, which renders this enzyme family highly attractive for targeted non-invasive functional imaging of tumors. Considering their function in matrix remodeling, malignant melanoma appears as particularly interesting neoplasia in this respect. For the development of radiotracers that enable PET imaging of the melanoma-associated lysyl oxidase activity, substrates derived from the type I collagen α1 N-telopeptide were labeled with fluorine-18 using N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB as prosthetic reagent. With regards to potential crosslinking to tumor-associated collagen in vivo, their interaction with triple-helical type I collagen was studied by SPR. A mouse model of human melanoma was established on the basis of the A375 cell line, for which the expression of the oncologically relevant lysyl oxidase isoforms LOX and LOXL2 was demonstrated in Western blot and immunohistochemical experiments. The radiopharmacological profiles of the peptidic radiotracers were evaluated in normal rats and A375 melanoma-bearing mice by ex vivo metabolite analysis, whole-body biodistribution studies and dynamic PET imaging. Out of three 18F-labeled telopeptide analogs, the one with the most favorable substrate properties has shown favorable tumor uptake and tumor-to-muscle ratio. Lysyl oxidase-mediated tumor uptake was proven by pharmacological inhibition using β-aminopropionitrile and by employing negative-control analogs of impeded or abolished targeting capability. The latter were obtained by substituting the lysine residue by ornithine and norleucine, respectively. Comparing the tumor uptake of the lysine-containing peptide with that of the non-functional analogs indicate the feasibility of lysyl oxidase imaging in melanoma using substrate-based radiotracers.

  14. Evaluation of Fluorine-18-Labeled α1(I)-N-Telopeptide Analogs as Substrate-Based Radiotracers for PET Imaging of Melanoma-Associated Lysyl Oxidase.

    Science.gov (United States)

    Kuchar, Manuela; Neuber, Christin; Belter, Birgit; Bergmann, Ralf; Lenk, Jens; Wodtke, Robert; Kniess, Torsten; Steinbach, Jörg; Pietzsch, Jens; Löser, Reik

    2018-01-01

    Accumulating evidence suggests an unequivocal role of lysyl oxidases as key players of tumor progression and metastasis, which renders this enzyme family highly attractive for targeted non-invasive functional imaging of tumors. Considering their function in matrix remodeling, malignant melanoma appears as particularly interesting neoplasia in this respect. For the development of radiotracers that enable PET imaging of the melanoma-associated lysyl oxidase activity, substrates derived from the type I collagen α1 N-telopeptide were labeled with fluorine-18 using N -succinimidyl 4-[ 18 F]fluorobenzoate ([ 18 F]SFB) as prosthetic reagent. With regards to potential crosslinking to tumor-associated collagen in vivo , their interaction with triple-helical type I collagen was studied by SPR. A mouse model of human melanoma was established on the basis of the A375 cell line, for which the expression of the oncologically relevant lysyl oxidase isoforms LOX and LOXL2 was demonstrated in Western blot and immunohistochemical experiments. The radiopharmacological profiles of the peptidic radiotracers were evaluated in normal rats and A375 melanoma-bearing mice by ex vivo metabolite analysis, whole-body biodistribution studies and dynamic PET imaging. Out of three 18 F-labeled telopeptide analogs, the one with the most favorable substrate properties has shown favorable tumor uptake and tumor-to-muscle ratio. Lysyl oxidase-mediated tumor uptake was proven by pharmacological inhibition using β-aminopropionitrile and by employing negative-control analogs of impeded or abolished targeting capability. The latter were obtained by substituting the lysine residue by ornithine and norleucine, respectively. Comparing the tumor uptake of the lysine-containing peptide with that of the non-functional analogs indicate the feasibility of lysyl oxidase imaging in melanoma using substrate-based radiotracers.

  15. Temperature dependence of the activity of polyphenol peroxidases and polyphenol oxidases in modern and buried soils

    Science.gov (United States)

    Yakushev, A. V.; Kuznetsova, I. N.; Blagodatskaya, E. V.; Blagodatsky, S. A.

    2014-05-01

    Under conditions of the global climate warming, the changes in the reserves of soil humus depend on the temperature sensitivities of polyphenol peroxidases (PPPOs) and polyphenol oxidases (PPOs). They play an important role in lignin decomposition, mineralization, and humus formation. The temperature dependence of the potential enzyme activity in modern and buried soils has been studied during incubation at 10 or 20°C. The experimental results indicate that it depends on the availability of the substrate and the presence of oxygen. The activity of PPOs during incubation in the absence of oxygen for two months decreases by 2-2.5 times, which is balanced by an increase in the activity of PPPOs by 2-3 times. The increase in the incubation temperature to 20°C and the addition of glucose accelerates this transition due to the more abrupt decrease in the activity of PPOs. The preincubation of the soil with glucose doubles the activity of PPPOs but has no significant effect on the activity of PPOs. The different effects of temperature on two groups of the studied oxidases and the possibility of substituting enzymes by those of another type under changing aeration conditions should be taken into consideration in predicting the effect of the climate warming on the mineralization of the soil organic matter. The absence of statistically significant differences in the enzymatic activity between the buried and modern soil horizons indicates the retention by the buried soil of some of its properties (soil memory) and the rapid restoration of high enzymatic activity during the preincubation.

  16. Purification and partial amino-acid sequence of gibberellin 20-oxidase from Cucurbita maxima L. endosperm.

    Science.gov (United States)

    Lange, T

    1994-01-01

    Gibberellin (GA) 20-oxidase was purified to apparent homogeneity from Cucurbita maxima endosperm by fractionated ammonium-sulphate precipitation, gel-filtration chromatography and anion-exchange and hydrophobic-interaction high-performance liquid chromatography (HPLC). Average purification after the last step was 55-fold with 3.9% of the activity recovered. The purest single fraction was enriched 101-fold with 0.2% overall recovery. Apparent relative molecular mass of the enzyme was 45 kDa, as determined by gel-filtration HPLC and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, indicating that GA 20-oxidase is probably a monomeric enzyme. The purified enzyme degraded on two-dimensional gel electrophoresis, giving two protein spots: a major one corresponding to a molecular mass of 30 kDa and a minor one at 45 kDa. The isoelectric point for both was 5.4. The amino-acid sequences of the amino-terminus of the purified enzyme and of two peptides from a tryptic digest were determined. The purified enzyme catalysed the sequential conversion of [14C]GA12 to [14C]GA15, [14C]GA24 and [14C]GA25, showing that carbon atom 20 was oxidised to the corresponding alcohol, aldehyde and carboxylic acid in three consecutive reactions. [14C]Gibberellin A53 was similarly converted to [14C]GA44, [14C]GA19, [14C]GA17 and small amounts of a fourth product, which was preliminarily identified as [14C]GA20, a C19-gibberellin. All GAs except [14C]GA20 were identified by combined gas chromatography-mass spectrometry. The cofactor requirements in the absence of dithiothreitol were essentially as in its presence (Lange et al., Planta 195, 98-107, 1994), except that ascorbate was essential for enzyme activity and the optimal concentration of catalase was lower.

  17. An Adaptation to Low Copper in Candida albicans Involving SOD Enzymes and the Alternative Oxidase.

    Directory of Open Access Journals (Sweden)

    Chynna N Broxton

    Full Text Available In eukaryotes, the Cu/Zn superoxide dismutase (SOD1 is a major cytosolic cuproprotein with a small fraction residing in the mitochondrial intermembrane space (IMS to protect against respiratory superoxide. Curiously, the opportunistic human fungal pathogen Candida albicans is predicted to express two cytosolic SODs including Cu/Zn containing SOD1 and manganese containing SOD3. As part of a copper starvation response, C. albicans represses SOD1 and induces the non-copper alternative SOD3. While both SOD1 and SOD3 are predicted to exist in the same cytosolic compartment, their potential role in mitochondrial oxidative stress had yet to be investigated. We show here that under copper replete conditions, a fraction of the Cu/Zn containing SOD1 localizes to the mitochondrial IMS to guard against mitochondrial superoxide. However in copper starved cells, localization of the manganese containing SOD3 is restricted to the cytosol leaving the mitochondrial IMS devoid of SOD. We observe that during copper starvation, an alternative oxidase (AOX form of respiration is induced that is not coupled to ATP synthesis but maintains mitochondrial superoxide at low levels even in the absence of IMS SOD. Surprisingly, the copper-dependent cytochrome c oxidase (COX form of respiration remains high with copper starvation. We provide evidence that repression of SOD1 during copper limitation serves to spare copper for COX and maintain COX respiration. Overall, the complex copper starvation response of C. albicans involving SOD1, SOD3 and AOX minimizes mitochondrial oxidative damage whilst maximizing COX respiration essential for fungal pathogenesis.

  18. Facile direct electron transfer in glucose oxidase modified electrodes

    International Nuclear Information System (INIS)

    Wang Dan; Chen Liwei

    2009-01-01

    Glucose oxidase (GOx) is widely used in the glucose biosensor industry. However, mediatorless direct electron transfer (DET) from GOx to electrode surfaces is very slow. Recently, mediatorless DET has been reported via the incorporation of nanomaterials such as carbon nanotubes and nanoparticles in the modification of electrodes. Here we report GOx electrodes showing DET without the need for any nanomaterials. The enzyme after immobilization with poly-L-lysine (PLL) and Nafion retains the biocatalytic activities and oxidizes glucose efficiently. The amperometric response of Nafion-PLL-GOx modified electrode is linearly proportional to the concentration of glucose up to 10 mM with a sensitivity of 0.75 μA/mM at a low detection potential (-0.460 V vs. Ag/AgCl). The methodology developed in this study will have impact on glucose biosensors and biofuel cells and may potentially simplify enzyme immobilization in other biosensing systems.

  19. Low platelet monoamine oxidase activity in pathological gambling

    International Nuclear Information System (INIS)

    Carrasco, J.L.; Saiz-Ruiz, J.; Hollander, E.; Cesar, J.; Lopez-Ibor, J.J. Jr.

    1994-01-01

    Decreased platelet monoamine oxidase (MAO) activity has been reported in association with sensation-seeking personality type and in some mental disorders associated with a lack of impulse control. Pathological gambling itself has been related with both sensation-seeking and reduced impulse control. Platelet MAO activity was investigated in 15 DSM-III-R pathological gamblers from our outpatient clinic. Gamblers had a significantly lower platelet MAO activity than a group of 25 healthy controls. The range of MAO levels in gamblers was also significantly shorter than in controls. In controls, platelet MAO levels showed the previously described negative correlations with sensation-seeking scores but not in gamblers. The findings are consistent with previous studies showing an association of low platelet MAO activity with impulse control disorders and raise some interesting therapeutic alternatives for pathological gambling. (au) (40 refs.)

  20. Dual oxidase in mucosal immunity and host-microbe homeostasis.

    Science.gov (United States)

    Bae, Yun Soo; Choi, Myoung Kwon; Lee, Won-Jae

    2010-07-01

    Mucosal epithelia are in direct contact with microbes, which range from beneficial symbionts to pathogens. Accordingly, hosts must have a conflicting strategy to combat pathogens efficiently while tolerating symbionts. Recent progress has revealed that dual oxidase (DUOX) plays a key role in mucosal immunity in organisms that range from flies to humans. Information from the genetic model of Drosophila has advanced our understanding of the regulatory mechanism of DUOX and its role in mucosal immunity. Further investigations of DUOX regulation in response to symbiotic or non-symbiotic bacteria and the in vivo consequences in host physiology will give a novel insight into the microbe-controlling system of the mucosa. Copyright 2010 Elsevier Ltd. All rights reserved.

  1. Polyphenol Oxidases in Crops: Biochemical, Physiological and Genetic Aspects

    Directory of Open Access Journals (Sweden)

    Francesca Taranto

    2017-02-01

    Full Text Available Enzymatic browning is a colour reaction occurring in plants, including cereals, fruit and horticultural crops, due to oxidation during postharvest processing and storage. This has a negative impact on the colour, flavour, nutritional properties and shelf life of food products. Browning is usually caused by polyphenol oxidases (PPOs, following cell damage caused by senescence, wounding and the attack of pests and pathogens. Several studies indicated that PPOs play a role in plant immunity, and emerging evidence suggested that PPOs might also be involved in other physiological processes. Genomic investigations ultimately led to the isolation of PPO homologs in several crops, which will be possibly characterized at the functional level in the near future. Here, focusing on the botanic families of Poaceae and Solanaceae, we provide an overview on available scientific literature on PPOs, resulting in useful information on biochemical, physiological and genetic aspects.

  2. The Membrane Modulates Internal Proton Transfer in Cytochrome c Oxidase

    DEFF Research Database (Denmark)

    Öjemyr, Linda Nasvik; Ballmoos, Christoph von; Faxén, Kristina

    2012-01-01

    The functionality of membrane proteins is often modulated by the surrounding membrane. Here, we investigated the effect of membrane reconstitution of purified cytochrome c oxidase (CytcO) on the kinetics and thermodynamics of internal electron and proton-transfer reactions during O-2 reduction...... DOPC lipids. In conclusion, the data show that the membrane significantly modulates internal charge-transfer reactions and thereby the function of the membrane-bound enzyme.......-glycerol) (DOPG). In addition, a small Change in the internal Cu-A-heme a electron equilibrium constant was observed. This effect was lipid-dependent and explained in terms of a lower electrostatic potential within the membrane-spanning part of the protein with the anionic DOPG lipids than with the zwitterionic...

  3. Low platelet monoamine oxidase activity in pathological gambling

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco, J.L. [Department of Psychiatry, Centro de Salud Mental, Parla Madrid (Spain); Saiz-Ruiz, J. [Department of Psychiatry and Haematology, Hospital Ramon y Cajal, Madrid (Spain); Hollander, E. [Department of Psychiatry, Mount Sinai School of Medicine, Queens Hospital Center, New York (United States); Cesar, J. [Department of Haematology, Hospital Ramon y Cajal, Madrid (Spain); Lopez-Ibor, J.J. Jr. [Department of Psychiatry, Hospital San Carlos, Complutense University, Madrid (Spain)

    1994-12-01

    Decreased platelet monoamine oxidase (MAO) activity has been reported in association with sensation-seeking personality type and in some mental disorders associated with a lack of impulse control. Pathological gambling itself has been related with both sensation-seeking and reduced impulse control. Platelet MAO activity was investigated in 15 DSM-III-R pathological gamblers from our outpatient clinic. Gamblers had a significantly lower platelet MAO activity than a group of 25 healthy controls. The range of MAO levels in gamblers was also significantly shorter than in controls. In controls, platelet MAO levels showed the previously described negative correlations with sensation-seeking scores but not in gamblers. The findings are consistent with previous studies showing an association of low platelet MAO activity with impulse control disorders and raise some interesting therapeutic alternatives for pathological gambling. (au) (40 refs.).

  4. Optical characterization of porous silicon microcavities for glucose oxidase biosensing

    Science.gov (United States)

    Palestino, G.; Agarwal, V.; Garcia, D. B.; Legros, R.; Pérez, E.; Gergely, C.

    2008-04-01

    PSi microcavity (PSiMc) is characterized by a narrow resonance peak in the optical spectrum that is very sensitive to small changes in the refractive index. We report that the resonant optical cavities of PSi structures can be used to enhance the detection of labeled fluorescent biomolecules. Various PSi configurations were tested in order to compare the optical response of the PSi devices to the capture of organic molecules. Morphological and topographical analyses were performed on PSiMc using Atomic Force (AFM) and Scanning Electron (SEM) microscopies. The heterogeneity in pores lengths resulting from etching process assures a better penetration of larger molecules into the pores and sensor sensitivity depends on the pore size. Molecular detection is monitored by the successive red shifts in the reflectance spectra after the stabilization of PSiMc with 3-aminopropyltriethoxysilane (APTES). The glucose oxidase was cross linked into the PSiMc structures following a silane-glutaraldehyde (GTA) chemistry.

  5. Magnetic field effects on brain monoamine oxidase activity

    Energy Technology Data Exchange (ETDEWEB)

    Borets, V.M.; Ostrovskiy, V.Yu.; Bankovskiy, A.A.; Dudinskaya, T.F.

    1985-03-01

    In view of the increasing use of magnetotherapy, studies were conducted on the effects of 35 mTesla magnetic fields on monoamine oxidase activity in the rat brain. Under in vitro conditions a constant magnetic field in the continuous mode was most effective in inhibiting deamination of dopamine following 1 min exposure, while in vivo studies with 8 min or 10 day exposures showed that inhibition was obtained only with a variable field in the continuous mode. However, inhibition of dopamine deamination was only evident within the first 24 h after exposure was terminated. In addition, in none of the cases was norepinephrine deamination inhibited. The effects of the magnetic fields were, therefore, transient and selective with the CNS as the target system. 9 references.

  6. Molecular Dynamic Studies of the Complex Polyethylenimine and Glucose Oxidase.

    Science.gov (United States)

    Szefler, Beata; Diudea, Mircea V; Putz, Mihai V; Grudzinski, Ireneusz P

    2016-10-27

    Glucose oxidase (GOx) is an enzyme produced by Aspergillus, Penicillium and other fungi species. It catalyzes the oxidation of β-d-glucose (by the molecular oxygen or other molecules, like quinones, in a higher oxidation state) to form d-glucono-1,5-lactone, which hydrolyses spontaneously to produce gluconic acid. A coproduct of this enzymatic reaction is hydrogen peroxide (H₂O₂). GOx has found several commercial applications in chemical and pharmaceutical industries including novel biosensors that use the immobilized enzyme on different nanomaterials and/or polymers such as polyethylenimine (PEI). The problem of GOx immobilization on PEI is retaining the enzyme native activity despite its immobilization onto the polymer surface. Therefore, the molecular dynamic (MD) study of the PEI ligand (C14N8_07_B22) and the GOx enzyme (3QVR) was performed to examine the final complex PEI-GOx stabilization and the affinity of the PEI ligand to the docking sites of the GOx enzyme. The docking procedure showed two places/regions of major interaction of the protein with the polymer PEI: (LIG1) of -5.8 kcal/mol and (LIG2) of -4.5 kcal/mol located inside the enzyme and on its surface, respectively. The values of enthalpy for the PEI-enzyme complex, located inside of the protein (LIG1) and on its surface (LIG2) were computed. Docking also discovered domains of the GOx protein that exhibit no interactions with the ligand or have even repulsive characteristics. The structural data clearly indicate some differences in the ligand PEI behavior bound at the two places/regions of glucose oxidase.

  7. Apocynin: Chemical and Biophysical Properties of a NADPH Oxidase Inhibitor

    Directory of Open Access Journals (Sweden)

    Valdecir F. Ximenes

    2013-03-01

    Full Text Available Apocynin is the most employed inhibitor of NADPH oxidase (NOX, a multienzymatic complex capable of catalyzing the one-electron reduction of molecular oxygen to the superoxide anion. Despite controversies about its selectivity, apocynin has been used as one of the most promising drugs in experimental models of inflammatory and neurodegenerative diseases. Here, we aimed to study the chemical and biophysical properties of apocynin. The oxidation potential was determined by cyclic voltammetry (Epa = 0.76V, the hydrophobicity index was calculated (logP = 0.83 and the molar absorption coefficient was determined (e275nm = 1.1 × 104 M−1 cm−1. Apocynin was a weak free radical scavenger (as measured using the DPPH, peroxyl radical and nitric oxide assays when compared to protocatechuic acid, used here as a reference antioxidant. On the other hand, apocynin was more effective than protocatechuic acid as scavenger of the non-radical species hypochlorous acid. Apocynin reacted promptly with the non-radical reactive species H2O2 only in the presence of peroxidase. This finding is relevant, since it represents a new pathway for depleting H2O2 in cellular experimental models, besides the direct inhibition of NADPH oxidase. This could be relevant for its application as an inhibitor of NOX4, since this isoform produces H2O2 and not superoxide anion. The binding parameters calculated by fluorescence quenching showed that apocynin binds to human serum albumin (HSA with a binding affinity of 2.19 × 104 M−1. The association did not alter the secondary and tertiary structure of HSA, as verified by synchronous fluorescence and circular dichroism. The displacement of fluorescent probes suggested that apocynin binds to site I and site II of HSA. Considering the current biomedical applications of this phytochemical, the dissemination of these chemical and biophysical properties can be very helpful for scientists and physicians interested in the use of apocynin.

  8. Molecular Dynamic Studies of the Complex Polyethylenimine and Glucose Oxidase

    Directory of Open Access Journals (Sweden)

    Beata Szefler

    2016-10-01

    Full Text Available Glucose oxidase (GOx is an enzyme produced by Aspergillus, Penicillium and other fungi species. It catalyzes the oxidation of β-d-glucose (by the molecular oxygen or other molecules, like quinones, in a higher oxidation state to form d-glucono-1,5-lactone, which hydrolyses spontaneously to produce gluconic acid. A coproduct of this enzymatic reaction is hydrogen peroxide (H2O2. GOx has found several commercial applications in chemical and pharmaceutical industries including novel biosensors that use the immobilized enzyme on different nanomaterials and/or polymers such as polyethylenimine (PEI. The problem of GOx immobilization on PEI is retaining the enzyme native activity despite its immobilization onto the polymer surface. Therefore, the molecular dynamic (MD study of the PEI ligand (C14N8_07_B22 and the GOx enzyme (3QVR was performed to examine the final complex PEI-GOx stabilization and the affinity of the PEI ligand to the docking sites of the GOx enzyme. The docking procedure showed two places/regions of major interaction of the protein with the polymer PEI: (LIG1 of −5.8 kcal/mol and (LIG2 of −4.5 kcal/mol located inside the enzyme and on its surface, respectively. The values of enthalpy for the PEI-enzyme complex, located inside of the protein (LIG1 and on its surface (LIG2 were computed. Docking also discovered domains of the GOx protein that exhibit no interactions with the ligand or have even repulsive characteristics. The structural data clearly indicate some differences in the ligand PEI behavior bound at the two places/regions of glucose oxidase.

  9. NADPH Oxidase Activity in Cerebral Arterioles Is a Key Mediator of Cerebral Small Vessel Disease—Implications for Prevention

    Directory of Open Access Journals (Sweden)

    Mark F. McCarty

    2015-04-01

    Full Text Available Cerebral small vessel disease (SVD, a common feature of brain aging, is characterized by lacunar infarcts, microbleeds, leukoaraiosis, and a leaky blood-brain barrier. Functionally, it is associated with cognitive decline, dementia, depression, gait abnormalities, and increased risk for stroke. Cerebral arterioles in this syndrome tend to hypertrophy and lose their capacity for adaptive vasodilation. Rodent studies strongly suggest that activation of Nox2-dependent NADPH oxidase activity is a crucial driver of these structural and functional derangements of cerebral arterioles, in part owing to impairment of endothelial nitric oxide synthase (eNOS activity. This oxidative stress may also contribute to the breakdown of the blood-brain barrier seen in SVD. Hypertension, aging, metabolic syndrome, smoking, hyperglycemia, and elevated homocysteine may promote activation of NADPH oxidase in cerebral arterioles. Inhibition of NADPH oxidase with phycocyanobilin from spirulina, as well as high-dose statin therapy, may have potential for prevention and control of SVD, and high-potassium diets merit study in this regard. Measures which support effective eNOS activity in other ways—exercise training, supplemental citrulline, certain dietary flavonoids (as in cocoa and green tea, and capsaicin, may also improve the function of cerebral arterioles. Asian epidemiology suggests that increased protein intakes may decrease risk for SVD; conceivably, arginine and/or cysteine—which boosts tissue glutathione synthesis, and can be administered as N-acetylcysteine—mediate this benefit. Ameliorating the risk factors for SVD—including hypertension, metabolic syndrome, hyperglycemia, smoking, and elevated homocysteine—also may help to prevent and control this syndrome, although few clinical trials have addressed this issue to date.

  10. NADPH Oxidase Activity in Cerebral Arterioles Is a Key Mediator of Cerebral Small Vessel Disease-Implications for Prevention.

    Science.gov (United States)

    McCarty, Mark F

    2015-04-15

    Cerebral small vessel disease (SVD), a common feature of brain aging, is characterized by lacunar infarcts, microbleeds, leukoaraiosis, and a leaky blood-brain barrier. Functionally, it is associated with cognitive decline, dementia, depression, gait abnormalities, and increased risk for stroke. Cerebral arterioles in this syndrome tend to hypertrophy and lose their capacity for adaptive vasodilation. Rodent studies strongly suggest that activation of Nox2-dependent NADPH oxidase activity is a crucial driver of these structural and functional derangements of cerebral arterioles, in part owing to impairment of endothelial nitric oxide synthase (eNOS) activity. This oxidative stress may also contribute to the breakdown of the blood-brain barrier seen in SVD. Hypertension, aging, metabolic syndrome, smoking, hyperglycemia, and elevated homocysteine may promote activation of NADPH oxidase in cerebral arterioles. Inhibition of NADPH oxidase with phycocyanobilin from spirulina, as well as high-dose statin therapy, may have potential for prevention and control of SVD, and high-potassium diets merit study in this regard. Measures which support effective eNOS activity in other ways-exercise training, supplemental citrulline, certain dietary flavonoids (as in cocoa and green tea), and capsaicin, may also improve the function of cerebral arterioles. Asian epidemiology suggests that increased protein intakes may decrease risk for SVD; conceivably, arginine and/or cysteine-which boosts tissue glutathione synthesis, and can be administered as N-acetylcysteine-mediate this benefit. Ameliorating the risk factors for SVD-including hypertension, metabolic syndrome, hyperglycemia, smoking, and elevated homocysteine-also may help to prevent and control this syndrome, although few clinical trials have addressed this issue to date.

  11. Low-Dose Dextromethorphan, a NADPH Oxidase Inhibitor, Reduces Blood Pressure and Enhances Vascular Protection in Experimental Hypertension

    Science.gov (United States)

    Wu, Tao-Cheng; Chao, Chih-Yu; Lin, Shing-Jong; Chen, Jaw-Wen

    2012-01-01

    Background Vascular oxidative stress may be increased with age and aggravate endothelial dysfunction and vascular injury in hypertension. This study aimed to investigate the effects of dextromethorphan (DM), a NADPH oxidase inhibitor, either alone or in combination treatment, on blood pressure (BP) and vascular protection in aged spontaneous hypertensive rats (SHRs). Methodology/Principal Findings Eighteen-week-old WKY rats and SHRs were housed for 2 weeks. SHRs were randomly assigned to one of the 12 groups: untreated; DM monotherapy with 1, 5 or 25 mg/kg/day; amlodipine (AM, a calcium channel blocker) monotherapy with 1 or 5 mg/kg/day; and combination therapy of DM 1, 5 or 25 mg/kg/day with AM 1 or 5 mg/kg/day individually for 4 weeks. The in vitro effects of DM were also examined. In SHRs, AM monotherapy dose-dependently reduced arterial systolic BP. DM in various doses significantly and similarly reduced arterial systolic BP. Combination of DM with AM gave additive effects on BP reduction. DM, either alone or in combination with AM, improved aortic endothelial function indicated by ex vivo acetylcholine-induced relaxation. The combination of low-dose DM with AM gave most significant inhibition on aortic wall thickness in SHRs. Plasma total antioxidant status was significantly increased by all the therapies except for the combination of high-dose DM with high-dose AM. Serum nitrite and nitrate level was significantly reduced by AM but not by DM or the combination of DM with AM. Furthermore, in vitro treatment with DM reduced angiotensin II-induced reactive oxygen species and NADPH oxidase activation in human aortic endothelial cells. Conclusions/Significance Treatment of DM reduced BP and enhanced vascular protection probably by inhibiting vascular NADPH oxidase in aged hypertensive animals with or without AM treatment. It provides the potential rationale to a novel combination treatment with low-dose DM and AM in clinical hypertension. PMID:23049937

  12. Low-dose dextromethorphan, a NADPH oxidase inhibitor, reduces blood pressure and enhances vascular protection in experimental hypertension.

    Directory of Open Access Journals (Sweden)

    Tao-Cheng Wu

    Full Text Available BACKGROUND: Vascular oxidative stress may be increased with age and aggravate endothelial dysfunction and vascular injury in hypertension. This study aimed to investigate the effects of dextromethorphan (DM, a NADPH oxidase inhibitor, either alone or in combination treatment, on blood pressure (BP and vascular protection in aged spontaneous hypertensive rats (SHRs. METHODOLOGY/PRINCIPAL FINDINGS: Eighteen-week-old WKY rats and SHRs were housed for 2 weeks. SHRs were randomly assigned to one of the 12 groups: untreated; DM monotherapy with 1, 5 or 25 mg/kg/day; amlodipine (AM, a calcium channel blocker monotherapy with 1 or 5 mg/kg/day; and combination therapy of DM 1, 5 or 25 mg/kg/day with AM 1 or 5 mg/kg/day individually for 4 weeks. The in vitro effects of DM were also examined. In SHRs, AM monotherapy dose-dependently reduced arterial systolic BP. DM in various doses significantly and similarly reduced arterial systolic BP. Combination of DM with AM gave additive effects on BP reduction. DM, either alone or in combination with AM, improved aortic endothelial function indicated by ex vivo acetylcholine-induced relaxation. The combination of low-dose DM with AM gave most significant inhibition on aortic wall thickness in SHRs. Plasma total antioxidant status was significantly increased by all the therapies except for the combination of high-dose DM with high-dose AM. Serum nitrite and nitrate level was significantly reduced by AM but not by DM or the combination of DM with AM. Furthermore, in vitro treatment with DM reduced angiotensin II-induced reactive oxygen species and NADPH oxidase activation in human aortic endothelial cells. CONCLUSIONS/SIGNIFICANCE: Treatment of DM reduced BP and enhanced vascular protection probably by inhibiting vascular NADPH oxidase in aged hypertensive animals with or without AM treatment. It provides the potential rationale to a novel combination treatment with low-dose DM and AM in clinical hypertension.

  13. Quinolinic Carboxylic Acid Derivatives as Potential Multi-target Compounds for Neurodegeneration: Monoamine Oxidase and Cholinesterase Inhibition.

    Science.gov (United States)

    Khan, Nehal A; Khan, Imtiaz; Abid, Syed M A; Zaib, Sumera; Ibrar, Aliya; Andleeb, Hina; Hameed, Shahid; Iqbal, Jamshed

    2018-01-01

    Parkinson's disease (PD), a debilitating and progressive disorder, is among the most challenging and devastating neurodegenerative diseases predominantly affecting the people over 60 years of age. To confront PD, an advanced and operational strategy is to design single chemical functionality able to control more than one target instantaneously. In this endeavor, for the exploration of new and efficient inhibitors of Parkinson's disease, we synthesized a series of quinoline carboxylic acids (3a-j) and evaluated their in vitro monoamine oxidase and cholinesterase inhibitory activities. The molecular docking and in silico studies of the most potent inhibitors were performed to identify the probable binding modes in the active site of the monoamine oxidase enzymes. Moreover, molecular properties were calculated to evaluate the druglikeness of the compounds. The biological evaluation results revealed that the tested compounds were highly potent against monoamine oxidase (A & B), 3c targeted both the isoforms of MAO with IC50 values of 0.51 ± 0.12 and 0.51 ± 0.03 µM, respectively. The tested compounds also demonstrated high and completely selective inhibitory action against acetylcholinesterase (AChE) with IC50 values ranging from 4.36 to 89.24 µM. Among the examined derivatives, 3i was recognized as the most potent inhibitor of AChE with an IC50 value of 4.36 ± 0.12 ±µM. The compounds appear to be promising inhibitors and could be used for the future development of drugs targeting neurodegenerative disorders. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  14. The increasing role of monoamine oxidase type B inhibitors in Parkinson's disease therapy.

    Science.gov (United States)

    Elmer, Lawrence W; Bertoni, John M

    2008-11-01

    The role of monoamine oxidase type B inhibitors in the treatment of Parkinson's disease has expanded with the new monoamine oxidase B inhibitor rasagiline and a new formulation, selegiline oral disintegrating tablets. As primary therapy in early disease monoamine oxidase B inhibitors reduce motor disability and delay the need for levodopa. In more advanced disease requiring levodopa, adjunctive monoamine oxidase B inhibitors reduce 'off' time and may improve gait and freezing. Rasagiline and selegiline oral disintegrating tablets may reduce the safety risks associated with the amfetamine and methamfetamine metabolites of conventional oral selegiline while retaining or improving therapeutic efficacy. Articles were identified by searches of PubMed and searches on the Internet and reviewed. All articles and other referenced materials were retrieved using the keywords 'Parkinson's disease', 'treatment' and 'monoamine oxidase B inhibitor' and were published between 1960 and 2007, with older references selected for historical significance. Only papers published in English were reviewed. Accumulating data support the use of monoamine oxidase B inhibitors as monotherapy for early and mild Parkinson's disease and as adjunctive therapy for more advanced Parkinson's disease with levodopa-associated motor fluctuations. The recently released monoamine oxidase B inhibitor rasagiline and a new formulation, selegiline oral disintegrating tablets, have potential advantages over conventional oral selegiline.

  15. Molecular Basis for Converting (2S-Methylsuccinyl-CoA Dehydrogenase into an Oxidase

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    Simon Burgener

    2017-12-01

    Full Text Available Although flavoenzymes have been studied in detail, the molecular basis of their dioxygen reactivity is only partially understood. The members of the flavin adenosine dinucleotide (FAD-dependent acyl-CoA dehydrogenase and acyl-CoA oxidase families catalyze similar reactions and share common structural features. However, both enzyme families feature opposing reaction specificities in respect to dioxygen. Dehydrogenases react with electron transfer flavoproteins as terminal electron acceptors and do not show a considerable reactivity with dioxygen, whereas dioxygen serves as a bona fide substrate for oxidases. We recently engineered (2S-methylsuccinyl-CoA dehydrogenase towards oxidase activity by rational mutagenesis. Here we characterized the (2S-methylsuccinyl-CoA dehydrogenase wild-type, as well as the engineered (2S-methylsuccinyl-CoA oxidase, in detail. Using stopped-flow UV-spectroscopy and liquid chromatography-mass spectrometry (LC-MS based assays, we explain the molecular base for dioxygen reactivity in the engineered oxidase and show that the increased oxidase function of the engineered enzyme comes at a decreased dehydrogenase activity. Our findings add to the common notion that an increased activity for a specific substrate is achieved at the expense of reaction promiscuity and provide guidelines for rational engineering efforts of acyl-CoA dehydrogenases and oxidases.

  16. Angiotensin II inhibits the Na+-K+ pump via PKC-dependent activation of NADPH oxidase.

    Science.gov (United States)

    White, Caroline N; Figtree, Gemma A; Liu, Chia-Chi; Garcia, Alvaro; Hamilton, Elisha J; Chia, Karin K M; Rasmussen, Helge H

    2009-04-01

    The sarcolemmal Na(+)-K(+) pump, pivotal in cardiac myocyte function, is inhibited by angiotensin II (ANG II). Since ANG II activates NADPH oxidase, we tested the hypothesis that NADPH oxidase mediates the pump inhibition. Exposure to 100 nmol/l ANG II increased superoxide-sensitive fluorescence of isolated rabbit ventricular myocytes. The increase was abolished by pegylated superoxide dismutase (SOD), by the NADPH oxidase inhibitor apocynin, and by myristolated inhibitory peptide to epsilon-protein kinase C (epsilonPKC), previously implicated in ANG II-induced Na(+)-K(+) pump inhibition. A role for epsilonPKC was also supported by an ANG II-induced increase in coimmunoprecipitation of epsilonPKC with the receptor for the activated kinase and with the cytosolic p47(phox) subunit of NADPH oxidase. ANG II decreased electrogenic Na(+)-K(+) pump current in voltage-clamped myocytes. The decrease was abolished by SOD, by the gp91ds inhibitory peptide that blocks assembly and activation of NADPH oxidase, and by epsilonPKC inhibitory peptide. Since colocalization should facilitate NADPH oxidase-dependent regulation of the Na(+)-K(+) pump, we examined whether there is physical association between the pump subunits and NADPH oxidase. The alpha(1)-subunit coimmunoprecipitated with caveolin 3 and with membrane-associated p22(phox) and cytosolic p47(phox) NADPH oxidase subunits at baseline. ANG II had no effect on alpha(1)/caveolin 3 or alpha(1)/p22(phox) interaction, but it increased alpha(1)/p47(phox) coimmunoprecipitation. We conclude that ANG II inhibits the Na(+)-K(+) pump via PKC-dependent NADPH oxidase activation.

  17. The Cytochrome bd Oxidase of Porphyromonas gingivalis Contributes to Oxidative Stress Resistance and Dioxygen Tolerance.

    Directory of Open Access Journals (Sweden)

    Julia Leclerc

    Full Text Available Porphyromonas gingivalis is an etiologic agent of periodontal disease in humans. The disease is associated with the formation of a mixed oral biofilm which is exposed to oxygen and environmental stress, such as oxidative stress. To investigate possible roles for cytochrome bd oxidase in the growth and persistence of this anaerobic bacterium inside the oral biofilm, mutant strains deficient in cytochrome bd oxidase activity were characterized. This study demonstrated that the cytochrome bd oxidase of Porphyromonas gingivalis, encoded by cydAB, was able to catalyse O2 consumption and was involved in peroxide and superoxide resistance, and dioxygen tolerance.

  18. Intramolecular electron transfer in ascorbate oxidase is enhanced in the presence of oxygen

    DEFF Research Database (Denmark)

    Farver, O; Wherland, S; Pecht, I

    1994-01-01

    Intramolecular electron transfer from the type 1 copper center to the type 3 copper(II) pair is induced in the multi-copper enzyme, ascorbate oxidase, following pulse radiolytic reduction of the type 1 Cu(II) ion. In the presence of a slight excess of dioxygen over ascorbate oxidase, interaction...... between the trinuclear copper center and O2 is observed even with singly reduced ascorbate oxidase molecules. Under these conditions, the rate constant for intramolecular electron transfer from type 1 Cu(I) to type 3 Cu(II) increases 5-fold to 1100 +/- 300 s-1 (20 degrees C, pH 5.8) as compared...

  19. Effects of temperature and glycerol and methanol-feeding profiles on the production of recombinant galactose oxidase in Pichia pastoris

    Science.gov (United States)

    Anasontzis, George E; Salazar Penã, Margarita; Spadiut, Oliver; Brumer, Harry; Olsson, Lisbeth

    2014-01-01

    Optimization of protein production from methanol-induced Pichia pastoris cultures is necessary to ensure high productivity rates and high yields of recombinant proteins. We investigated the effects of temperature and different linear or exponential methanol-feeding rates on the production of recombinant Fusarium graminearum galactose oxidase (EC 1.1.3.9) in a P. pastoris Mut+ strain, under regulation of the AOX1 promoter. We found that low exponential methanol feeding led to 1.5-fold higher volumetric productivity compared to high exponential feeding rates. The duration of glycerol feeding did not affect the subsequent product yield, but longer glycerol feeding led to higher initial biomass concentration, which would reduce the oxygen demand and generate less heat during induction. A linear and a low exponential feeding profile led to productivities in the same range, but the latter was characterized by intense fluctuations in the titers of galactose oxidase and total protein. An exponential feeding profile that has been adapted to the apparent biomass concentration results in more stable cultures, but the concentration of recombinant protein is in the same range as when constant methanol feeding is employed. © 2014 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 30:728–735, 2014 PMID:24493559

  20. New insights into the roles of NADPH oxidases in sexual development and ascospore germination in Sordaria macrospora.

    Science.gov (United States)

    Dirschnabel, Daniela Elisabeth; Nowrousian, Minou; Cano-Domínguez, Nallely; Aguirre, Jesus; Teichert, Ines; Kück, Ulrich

    2014-03-01

    NADPH oxidase (NOX)-derived reactive oxygen species (ROS) act as signaling determinants that induce different cellular processes. To characterize NOX function during fungal development, we utilized the genetically tractable ascomycete Sordaria macrospora. Genome sequencing of a sterile mutant led us to identify the NADPH oxidase encoding nox1 as a gene required for fruiting body formation, regular hyphal growth, and hyphal fusion. These phenotypes are shared by nor1, lacking the NOX regulator NOR1. Further phenotypic analyses revealed a high correlation between increased ROS production and hyphal fusion deficiencies in nox1 and other sterile mutants. A genome-wide transcriptional profiling analysis of mycelia and isolated protoperithecia from wild type and nox1 revealed that nox1 inactivation affects the expression of genes related to cytoskeleton remodeling, hyphal fusion, metabolism, and mitochondrial respiration. Genetic analysis of nox2, lacking the NADPH oxidase 2 gene, nor1, and transcription factor deletion mutant ste12, revealed a strict melanin-dependent ascospore germination defect, indicating a common genetic pathway for these three genes. We report that gsa3, encoding a G-protein α-subunit, and sac1, encoding cAMP-generating adenylate cyclase, act in a separate pathway during the germination process. The finding that cAMP inhibits ascospore germination in a melanin-dependent manner supports a model in which cAMP inhibits NOX2 activity, thus suggesting a link between both pathways. Our results expand the current knowledge on the role of NOX enzymes in fungal development and provide a frame to define upstream and downstream components of the NOX signaling pathways in fungi.

  1. Three dimensional nano-assemblies of noble metal nanoparticle-infinite coordination polymers as specific oxidase mimetics for degradation of methylene blue without adding any cosubstrate.

    Science.gov (United States)

    Wang, Lihua; Zeng, Yi; Shen, Aiguo; Zhou, Xiaodong; Hu, Jiming

    2015-02-07

    Novel three-dimensional (3D) nano-assemblies of noble metal nanoparticle (NP)-infinite coordination polymers (ICPs) are conveniently fabricated through the infiltration of HAuCl4 into hollow Au@Ag@ICPs core-shell nanostructures and its replacement reaction with Au@Ag NPs. The present 3D nano-assemblies exhibit highly efficient and specific intrinsic oxidase-like activity even without adding any cosubstrate.

  2. Steady-state kinetics of substrate binding and iron release in tomato ACC oxidase.

    Science.gov (United States)

    Thrower, J S; Blalock, R; Klinman, J P

    2001-08-14

    1-Aminocyclopropane-1-carboxylate oxidase (ACC oxidase) catalyzes the last step in the biosynthetic pathway of the plant hormone, ethylene. This unusual reaction results in the oxidative ring cleavage of 1-aminocyclopropane carboxylate (ACC) into ethylene, cyanide, and CO2 and requires ferrous ion, ascorbate, and molecular oxygen for catalysis. A new purification procedure and assay method have been developed for tomato ACC oxidase that result in greatly increased enzymatic activity. This method allowed us to determine the rate of iron release from the enzyme and the effect of the activator, CO2, on this rate. Initial velocity studies support an ordered kinetic mechanism where ACC binds first followed by O2; ascorbate can bind after O2 or possibly before ACC. This kinetic mechanism differs from one recently proposed for the ACC oxidase from avocado.

  3. In vivo oxalate degradation by liposome encapsulated oxalate oxidase in rat model of hyperoxaluria

    Directory of Open Access Journals (Sweden)

    Tulika Dahiya

    2013-01-01

    Interpretation & conclusions: EMA-oxalate oxidase encapsulated liposome caused oxalate degradation in experimental hyperoxaluria indicating that the enzyme could be used as a therapeutic agent in hyperoxaluria leading to urinary stones.

  4. Action of DCCD on the H+/O stoichiometry of mitoplast cytochrome c oxidase.

    Science.gov (United States)

    Lehninger, A L; Reynafarje, B; Costa, L

    1985-01-01

    The mechanistic H+/O ejection stoichiometry of the cytochrome c oxidase reaction in rat liver mitoplasts is close to 4 at level flow when the reduced oxidase is pulsed with O2. Dicyclohexylcarbodiimide (DCCD) up to 30 nmol/mg protein fails to influence the rate of electron flow through the mitoplast oxidase, but inhibits H+ ejection. The inhibition of H+ ejection appears to be biphasic; ejection of 2-3 H+ per O is completely inhibited by very low DCCD, whereas inhibition of the remaining H+ ejection requires very much higher concentrations of DCCD. This effect suggests the occurrence of two types of H+ pumps in the native cytochrome oxidase of mitoplasts.

  5. Production of a new D-amino acid oxidase from the fungus Fusarium oxysporum.

    Science.gov (United States)

    Gabler, M; Fischer, L

    1999-08-01

    The fungus Fusarium oxysporum produced a D-amino acid oxidase (EC 1. 4.3.3) in a medium containing glucose as the carbon and energy source and ammonium sulfate as the nitrogen source. The specific D-amino acid oxidase activity was increased up to 12.5-fold with various D-amino acids or their corresponding derivatives as inducers. The best inducers were D-alanine (2.7 microkat/g of dry biomass) and D-3-aminobutyric acid (2.6 microkat/g of dry biomass). The addition of zinc ions was necessary to permit the induction of peroxisomal D-amino acid oxidase. Bioreactor cultivations were performed on a 50-liter scale, yielding a volumetric D-amino acid oxidase activity of 17 microkat liter(-1) with D-alanine as an inducer. Under oxygen limitation, the volumetric activity was increased threefold to 54 microkat liter(-1) (3,240 U liter(-1)).

  6. Interferon gamma/NADPH oxidase defence system in immunity and cancer

    Czech Academy of Sciences Publication Activity Database

    Hodný, Zdeněk; Reiniš, Milan; Hubáčková, Soňa; Vašicová, Pavla; Bartek, Jiří

    -, 01 Sep (2015) ISSN 2162-4011 Institutional support: RVO:68378050 ; RVO:61388971 Keywords : IFNγ * NADPH oxidase * immunity * cancer Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.266, year: 2014

  7. Metavanadate causes cellular accumulation of copper and decreased lysyl oxidase activity

    International Nuclear Information System (INIS)

    Cui, Changtai T.; Uriu-Adams, Janet Y.; Tchaparian, Eskouhie H.; Keen, Carl L.; Rucker, Robert B.

    2004-01-01

    Selected indices of copper metabolism in weanling rats and fibroblast cultures were progressively altered in response to increased levels of sodium metavanadate. In diets, vanadium was added in amounts ranging from 0 to 80 μg V/g of diet, that is, 0-1.6 μmol V/g of diet. In fibroblast cultures, vanadium ranged from 0 to 400 nmol V/ml. The inhibition of P-ATPase-7A activity by metavanadate, important to copper egress from cells, was a primary focus. In skin, and tendon, the copper concentration was increased in response to increased dietary levels of metavanadate, whereas lysyl oxidase activity, a secreted cuproprotein, was reduced. The reduction in lysyl oxidase activity was also accompanied by reduced redox cycling potential of isolated fractions of lysyl oxidase, presumably due to reduced lysyltyrosyl quinone (LTQ) formation at the active site of lysyl oxidase. In contrast, liver copper concentrations and plasma ceruloplasmin activity were not affected by metavanadate exposure. However, semicarbazide-sensitive benzylamine oxidase (SCBO) activity, which was taken as an indirect measure of vascular adhesive protein-1 (VAP-1), was increased. In cultured fibroblasts, cellular copper was also increased and lysyl oxidase decreased in response to metavanadate. Moreover, the steady-state levels of atp7a and lysyl oxidase mRNAs were not affected by addition of metavanadate to culture medium up to 200 nmol/ml. Taken together, these data suggest that pathways involving copper egress and lysyl oxidase activation are particularly sensitive to metavanadate exposure through processes that are predominately posttranslational

  8. Herbivore-plant interactions: mixed-function oxidases and secondary plant substances.

    Science.gov (United States)

    Brattsten, L B; Wilkinson, C F; Eisner, T

    1977-06-17

    The mixed-function oxidases of a polyphagous insect larva (the southern armyworm, Spodoptera eridania) were found to be induced by a diversity of secondary plant substances. The induction proceeds rapidly and in response to a small quantity of secondary substance. Following induction, the larva is less susceptible to dietary poisoning. It is argued that mixed-function oxidases play a major role in protecting herbivores against chemical stress from secondary plant substances.

  9. Process technology for the application of d-amino acid oxidases in pharmaceutical intermediate manufacturing

    DEFF Research Database (Denmark)

    Tindal, Stuart; Carr, Reuben; Archer, Ian V. J.

    2011-01-01

    Recent advances in biocatalysis have seen increased interest in the use of D-amino acid oxidase to synthesize optically pure amino acids. However, the creation of a genuine oxidase based platform technology will require suitable process technology as well as an understanding of the challenges...... and opportunities of a wider portfolio of synthetic targets. In this article we address some of the recent progress in process technology to enable the future development of a generic platform technology....

  10. Estimation of Anadara tuberculosa genetic diversity in five mangroves from Tumaco, using Cytochrome oxidase I enzyme

    Directory of Open Access Journals (Sweden)

    Esmeralda Chamorro L

    2016-09-01

    Full Text Available Objective. To estimate the genetic diversity of the Anadara tuberculosa en five mangrove swams of Tumaco, Nariño, Colombia using as a mitocondrial molecular marker the cytochromo oxidase sub-unit I (COI. Materials and methods. A total of 50 individuals were collected from the San Jorge, La Tiburonera, El Pajal, La Playa y Bajito Vaquería mangrove swamps, randomly selecting 10 specimens of each zone. The tissue sample was worked with absolute alcohol at ambient temperature in microtubes. DNA was extracted, and the mitocondrial DNA was amplified using the PCR technique (polymerase chain reaction. The amplified and quantified products of PCR were sequenced on both sides (Macrogen. Each one of the obtained sequences was edited and aligned. Later, the parameters of genetic diversity (haplotypical and nucleotidical were measured, and the analysis of distribution between frequency pairs (Mistmach distribution was elaborated. Finally, the analysis of nucleotidic variation and population structure (AMOVA was completed. Results. The amplified product gene weighed 710 bp. The haplotypical diversity reported for all the populations was high (0.683±0.060 and the reported nucleotídical diversity was low for all the populations (0.040±0.020. The AMOVA results indicate that the variance amongst populations is low (4.20% and that the variance within populations is high (95.80%. Conclusions. The studied populations are not structured and although there is a decrease of natural banks, the genetic diversity is high.

  11. [Role of mitochondrial alternative oxidase (AOX) pathway in photoprotection in Rumex K-1 leaves].

    Science.gov (United States)

    Meng, Xiang-Long; Zhang, Li-Tao; Zhang, Zi-Shan; Gao, Hui-Yuan; Meng, Qing-Wei

    2012-07-01

    Taking Rumex K-1 leaves as test materials, this paper studied the role of mitochondrial alternative oxidase (AOX) pathway in photoprotection under different light intensities. Under low light intensity (200 micromol x m(-2) x s(-1)), and after treated with salicylhydroxamic acid to inhibit the AOX pathway, the leaf actual photochemical efficiency of PS II, linear electron transport rate of photosynthesis, and photosynthetic O2 evolution rate all decreased significantly while the non-Q(B) reducing reaction center had a significant increase, indicating that under low light, the photoinhibition was aggravated while the scavenging enzymes of reactive oxygen species (ROS) increased, which avoided the over-accumulation of ROS and partially alleviated the photoinhibition of Rumex K-1 leaves. Under high light intensity (800 micromol x m(-2) x s(-1)), the inhibition of AOX pathway caused more severe photoinhibition, and the increased activities of ROS scavenging enzymes were insufficient to prevent the over-accumulation of ROS. This study demonstrated that AOX pathway played an important role in the photoprotection in Rumex K-1 leaves under both high and low light intensities, and the role of AOX pathway in photoprotection under high light could be irreplaceable by the other photoprotection pathways in chloroplast.

  12. Engineering an enantioselective amine oxidase for the synthesis of pharmaceutical building blocks and alkaloid natural products.

    Science.gov (United States)

    Ghislieri, Diego; Green, Anthony P; Pontini, Marta; Willies, Simon C; Rowles, Ian; Frank, Annika; Grogan, Gideon; Turner, Nicholas J

    2013-07-24

    The development of cost-effective and sustainable catalytic methods for the production of enantiomerically pure chiral amines is a key challenge facing the pharmaceutical and fine chemical industries. This challenge is highlighted by the estimate that 40-45% of drug candidates contain a chiral amine, fueling a demand for broadly applicable synthetic methods that deliver target structures in high yield and enantiomeric excess. Herein we describe the development and application of a "toolbox" of monoamine oxidase variants from Aspergillus niger (MAO-N) which display remarkable substrate scope and tolerance for sterically demanding motifs, including a new variant, which exhibits high activity and enantioselectivity toward substrates containing the aminodiphenylmethane (benzhydrylamine) template. By combining rational structure-guided engineering with high-throughput screening, it has been possible to expand the substrate scope of MAO-N to accommodate amine substrates containing bulky aryl substituents. These engineered MAO-N biocatalysts have been applied in deracemization reactions for the efficient asymmetric synthesis of the generic active pharmaceutical ingredients Solifenacin and Levocetirizine as well as the natural products (R)-coniine, (R)-eleagnine, and (R)-leptaflorine. We also report a novel MAO-N mediated asymmetric oxidative Pictet-Spengler approach to the synthesis of (R)-harmicine.

  13. Biphenyl Modulates the Expression and Function of Respiratory Oxidases in the Polychlorinated-Biphenyls Degrader Pseudomonas pseudoalcaligenes KF707

    Directory of Open Access Journals (Sweden)

    Federica Sandri

    2017-06-01

    Full Text Available Pseudomonas pseudoalcaligenes KF707 is a soil bacterium which is known for its capacity to aerobically degrade harmful organic compounds such as polychlorinated biphenyls (PCBs using biphenyl as co-metabolite. Here we provide the first genetic and functional analysis of the KF707 respiratory terminal oxidases in cells grown with two different carbon sources: glucose and biphenyl. We identified five terminal oxidases in KF707: two c(caa3 type oxidases (Caa3 and Ccaa3, two cbb3 type oxidases (Cbb31 and Cbb32, and one bd type cyanide-insensitive quinol oxidase (CIO. While the activity and expression of both Cbb31 and Cbb32 oxidases was prevalent in glucose grown cells as compared to the other oxidases, the activity and expression of the Caa3 oxidase increased considerably only when biphenyl was used as carbon source in contrast to the Cbb32 oxidase which was repressed. Further, the respiratory activity and expression of CIO was up-regulated in a Cbb31 deletion strain as compared to W.T. whereas the CIO up-regulation was not present in Cbb32 and C(caa3 deletion mutants. These results, together, reveal that both function and expression of cbb3 and caa3 type oxidases in KF707 are modulated by biphenyl which is the co-metabolite needed for the activation of the PCBs-degradation pathway.

  14. Construction of Mutant Glucose Oxidases with Increased Dye-Mediated Dehydrogenase Activity

    Science.gov (United States)

    Horaguchi, Yohei; Saito, Shoko; Kojima, Katsuhiro; Tsugawa, Wakako; Ferri, Stefano; Sode, Koji

    2012-01-01

    Mutagenesis studies on glucose oxidases (GOxs) were conducted to construct GOxs with reduced oxidase activity and increased dehydrogenase activity. We focused on two representative GOxs, of which crystal structures have already been reported—Penicillium amagasakiense GOx (PDB ID; 1gpe) and Aspergillus niger GOx (PDB ID; 1cf3). We constructed oxygen-interacting structural models for GOxs, and predicted the residues responsible for oxidative half reaction with oxygen on the basis of the crystal structure of cholesterol oxidase as well as on the fact that both enzymes are members of the glucose/methanol/choline (GMC) oxidoreductase family. Rational amino acid substitution resulted in the construction of an engineered GOx with drastically decreased oxidase activity and increased dehydrogenase activity, which was higher than that of the wild-type enzyme. As a result, the dehydrogenase/oxidase ratio of the engineered enzyme was more than 11-fold greater than that of the wild-type enzyme. These results indicate that alteration of the dehydrogenase/oxidase activity ratio of GOxs is possible by introducing a mutation into the putative functional residues responsible for oxidative half reaction with oxygen of these enzymes, resulting in a further increased dehydrogenase activity. This is the first study reporting the alteration of GOx electron acceptor preference from oxygen to an artificial electron acceptor. PMID:23203056

  15. Construction of Mutant Glucose Oxidases with Increased Dye-Mediated Dehydrogenase Activity

    Directory of Open Access Journals (Sweden)

    Koji Sode

    2012-11-01

    Full Text Available Mutagenesis studies on glucose oxidases (GOxs were conducted to construct GOxs with reduced oxidase activity and increased dehydrogenase activity. We focused on two representative GOxs, of which crystal structures have already been reported—Penicillium amagasakiense GOx (PDB ID; 1gpe and Aspergillus niger GOx (PDB ID; 1cf3. We constructed oxygen-interacting structural models for GOxs, and predicted the residues responsible for oxidative half reaction with oxygen on the basis of the crystal structure of cholesterol oxidase as well as on the fact that both enzymes are members of the glucose/methanol/choline (GMC oxidoreductase family. Rational amino acid substitution resulted in the construction of an engineered GOx with drastically decreased oxidase activity and increased dehydrogenase activity, which was higher than that of the wild-type enzyme. As a result, the dehydrogenase/oxidase ratio of the engineered enzyme was more than 11-fold greater than that of the wild-type enzyme. These results indicate that alteration of the dehydrogenase/oxidase activity ratio of GOxs is possible by introducing a mutation into the putative functional residues responsible for oxidative half reaction with oxygen of these enzymes, resulting in a further increased dehydrogenase activity. This is the first study reporting the alteration of GOx electron acceptor preference from oxygen to an artificial electron acceptor.

  16. [The X+ chronic granulomatous disease as a fabulous model to study the NADPH oxidase complex activation].

    Science.gov (United States)

    Stasia, Marie-José

    2007-05-01

    Chronic granulomatous disease (CGD) is a rare inherited disorder in which phagocytes lack NADPH oxidase activity. Patients with CGD suffer from recurrent bacterial and fungal infections because of the absence of superoxide anions (O2- degrees ) generatingsystem. The NADPH oxidase complex is composed of a membranous cytochrome b558, cytosolic proteins p67phox, p47phox, p40phox and two small GTPases Rac2 and Rap1A. Cytochrome b558 consists of two sub-units gp91phox and p22phox. The most common form of CGD is due to mutations in CYBB gene encoding gp91phox. In some rare cases, the mutated gp91phox is normally expressed but is devoided of oxidase activity. These variants called X+ CGD, have provided interesting informations about oxidase activation mechanisms. However modelization of such variants is necessary to obtain enough biological material for studies at the molecular level. A cellular model (knock-out PLB-985 cells) has been developed for expressing recombinant mutated gp91phox for functional analysis of the oxidase complex. Recent works demonstrated that this cell line genetically deficient in gp91phox is a powerful tool for functional analysis of the NADPH oxidase complex activation.

  17. Construction of mutant glucose oxidases with increased dye-mediated dehydrogenase activity.

    Science.gov (United States)

    Horaguchi, Yohei; Saito, Shoko; Kojima, Katsuhiro; Tsugawa, Wakako; Ferri, Stefano; Sode, Koji

    2012-11-02

    Mutagenesis studies on glucose oxidases (GOxs) were conducted to construct GOxs with reduced oxidase activity and increased dehydrogenase activity. We focused on two representative GOxs, of which crystal structures have already been reported—Penicillium amagasakiense GOx (PDB ID; 1gpe) and Aspergillus niger GOx (PDB ID; 1cf3). We constructed oxygen-interacting structural models for GOxs, and predicted the residues responsible for oxidative half reaction with oxygen on the basis of the crystal structure of cholesterol oxidase as well as on the fact that both enzymes are members of the glucose/methanol/choline (GMC) oxidoreductase family. Rational amino acid substitution resulted in the construction of an engineered GOx with drastically decreased oxidase activity and increased dehydrogenase activity, which was higher than that of the wild-type enzyme. As a result, the dehydrogenase/oxidase ratio of the engineered enzyme was more than 11-fold greater than that of the wild-type enzyme. These results indicate that alteration of the dehydrogenase/oxidase activity ratio of GOxs is possible by introducing a mutation into the putative functional residues responsible for oxidative half reaction with oxygen of these enzymes, resulting in a further increased dehydrogenase activity. This is the first study reporting the alteration of GOx electron acceptor preference from oxygen to an artificial electron acceptor.

  18. Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen

    International Nuclear Information System (INIS)

    Pasqualini, Stefania; Tedeschini, Emma; Frenguelli, Giuseppe; Wopfner, Nicole; Ferreira, Fatima; D'Amato, Gennaro; Ederli, Luisa

    2011-01-01

    Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O 3 ) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O 3 fumigation, with analysis of pollen viability, ROS and nitric oxide (NO) content, activity of nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase, and expression of major allergens. There was decreased pollen viability after O 3 fumigation, which indicates damage to the pollen membrane system, although the ROS and NO contents were not changed or were only slightly induced, respectively. Ozone exposure induced a significant enhancement of the ROS-generating enzyme NAD(P)H oxidase. The expression of the allergen Amb a 1 was not affected by O 3 , determined from the mRNA levels of the major allergens. We conclude that O 3 can increase ragweed pollen allergenicity through stimulation of ROS-generating NAD(P)H oxidase. - Highlights: → O 3 reduces the viability of ragweed pollen. → ROS and allergens of ragweed pollen were not affected by O 3 exposure. → O 3 enhances the activity of the ROS-generating enzyme NAD(P)H oxidase. → O 3 increases ragweed pollen allergenicity through NAD(P)H-oxidase stimulation. - This study focuses on the effects of the atmospheric pollutant ozone on ROS content and NAD(P)H oxidase activity of ragweed pollen grains.

  19. A decade of crystallization drops: crystallization of the cbb3 cytochrome c oxidase from Pseudomonas stutzeri.

    Science.gov (United States)

    Buschmann, Sabine; Richers, Sebastian; Ermler, Ulrich; Michel, Hartmut

    2014-04-01

    The cbb3 cytochrome c oxidases are distant members of the superfamily of heme copper oxidases. These terminal oxidases couple O2 reduction with proton transport across the plasma membrane and, as a part of the respiratory chain, contribute to the generation of an electrochemical proton gradient. Compared with other structurally characterized members of the heme copper oxidases, the recently determined cbb3 oxidase structure at 3.2 Å resolution revealed significant differences in the electron supply system, the proton conducting pathways and the coupling of O2 reduction to proton translocation. In this paper, we present a detailed report on the key steps for structure determination. Improvement of the protein quality was achieved by optimization of the number of lipids attached to the protein as well as the separation of two cbb3 oxidase isoenzymes. The exchange of n-dodecyl-β-D-maltoside for a precisely defined mixture of two α-maltosides and decanoylsucrose as well as the choice of the crystallization method had a most profound impact on crystal quality. This report highlights problems frequently encountered in membrane protein crystallization and offers meaningful approaches to improve crystal quality. © 2014 The Protein Society.

  20. Blockade of TGF-β 1 Signalling Inhibits Cardiac NADPH Oxidase Overactivity in Hypertensive Rats

    Directory of Open Access Journals (Sweden)

    José Luis Miguel-Carrasco

    2012-01-01

    Full Text Available NADPH oxidases constitute a major source of superoxide anion (⋅O2 - in hypertension. Several studies suggest an important role of NADPH oxidases in different effects mediated by TGF-β 1. In this study we show that chronic administration of P144, a peptide synthesized from type III TGF-β 1 receptor, significantly reduced the cardiac NADPH oxidase expression and activity as well as in the nitrotyrosine levels observed in control spontaneously hypertensive rats (V-SHR to levels similar to control normotensive Wistar Kyoto rats. In addition, P144 was also able to reduce the significant increases in the expression of collagen type I protein and mRNA observed in hearts from V-SHR. In addition, positive correlations between collagen expression, NADPH oxidase activity, and nitrotyrosine levels were found in all animals. Finally, TGF-β 1-stimulated Rat-2 exhibited significant increases in NADPH oxidase activity that was inhibited in the presence of P144. It could be concluded that the blockade of TGF-β 1 with P144 inhibited cardiac NADPH oxidase in SHR, thus adding new data to elucidate the involvement of this enzyme in the profibrotic actions of TGF-β 1.

  1. Preparation of biosensors by immobilization of polyphenol oxidase in conducting copolymers and their use in determination of phenolic compounds in red wine.

    Science.gov (United States)

    Böyükbayram, A Elif; Kiralp, Senem; Toppare, Levent; Yağci, Yusuf

    2006-10-01

    Electrochemically produced graft copolymers of thiophene capped polytetrahydofuran (TPTHF1 and TPTHF2) and pyrrole were achieved by constant potential electrolysis using sodium dodecylsulfate (SDS) as the supporting electrolyte. Characterizations were based on Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Electrical conductivities were measured by the four-probe technique. Novel biosensors for phenolic compounds were constructed by immobilizing polyphenol oxidase (PPO) into conducting copolymers prepared by electropolymerization of pyrrole with thiophene capped polytetrahydrofuran. Kinetic parameters, maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) and optimum conditions regarding temperature and pH were determined for the immobilized enzyme. Operational stability and shelf-life of the enzyme electrodes were investigated. Enzyme electrodes of polyphenol oxidase were used to determine the amount of phenolic compounds in two brands of Turkish red wines and found very useful owing to their high kinetic parameters and wide pH working range.

  2. Proline Oxidase (POX) as A Target for Cancer Therapy.

    Science.gov (United States)

    Kononczuk, Joanna; Czyzewska, Urszula; Moczydlowska, Joanna; Surażyński, Arkadiusz; Palka, Jerzy; Miltyk, Wojciech

    2015-01-01

    Proline dehydrogenase/proline oxidase (PRODH/POX) is an enzyme catalyzing the first step of proline degradation, during which ROS and/or ATP is generated. POX is widely distributed in living organisms and is responsible for a number of regulatory processes such as redox homeostasis, osmotic adaptation, cell signaling and oxidative stress. Recent data provided evidence that POX plays an important role in carcinogenesis and tumor growth. POX may induce apoptosis in both intrinsic and extrinsic way. Due to ROS generation, POX may induce caspase-9 activity, which mediates mitochondrial apoptosis (intrinsic apoptosis pathway). POX can also stimulate TRAIL (tumor necrosis factorrelated apoptosis inducing ligand) and DR5 (death receptor 5) expression, resulting in cleavage of procaspase-8 and thus extrinsic apoptotic pathway. However, this tumor suppressor in certain environmental conditions may act as a prosurvival factor. Genotoxic, inflammatory and metabolic stress may switch POX from tumor growth inhibiting to tumor growth supporting factor. The potential mechanisms which may regulate switching of POX mode are discussed in this review.

  3. Glucose Oxidase Immobilization on TMAH-Modified Bentonite

    Directory of Open Access Journals (Sweden)

    Ruth Chrisnasari

    2015-03-01

    Full Text Available The influence of bentonite modification by tetramethyl ammonium hydroxide (TMAH on its capability to immobilize glucose oxidase (GOX was studied. Modification of bentonite was conducted by the adding of 0-5% (v/v TMAH. The observed results show that the different concentrations of TMAH affect the percentage of immobilized enzyme. The results of this study show that the best concentration of TMAH is 5% (v/v which can immobilize up to 84.71% of GOX. X-ray diffraction (XRD and Fourier Transforms Infrared Spectroscopy (FTIR studies have been carried out to observe the structural changes in bentonite due to TMAH modification. The obtained immobilized GOX show the optimum catalytic activity on reaction temperature of 40-50 °C and pH of 7. The immobilized GOX kinetics at the optimum conditions determined the Km and Vmax value to be 4.96x10-2 mM and 4.99x10-3 mM.min-1 respectively. In addition, the immobilized GOX on TMAH-modified bentonite is stable enough so it could be re-used six times before its activity decreased by 39.44%.

  4. Introducing inducible fluorescent split cholesterol oxidase to mammalian cells.

    Science.gov (United States)

    Chernov, Konstantin G; Neuvonen, Maarit; Brock, Ivonne; Ikonen, Elina; Verkhusha, Vladislav V

    2017-05-26

    Cholesterol oxidase (COase) is a bacterial enzyme catalyzing the first step in the biodegradation of cholesterol. COase is an important biotechnological tool for clinical diagnostics and production of steroid drugs and insecticides. It is also used for tracking intracellular cholesterol; however, its utility is limited by the lack of an efficient temporal control of its activity. To overcome this we have developed a regulatable fragment complementation system for COase cloned from Chromobacterium sp. The enzyme was split into two moieties that were fused to FKBP (FK506-binding protein) and FRB (rapamycin-binding domain) pair and split GFP fragments. The addition of rapamycin reconstituted a fluorescent enzyme, termed split GFP-COase, the fluorescence level of which correlated with its oxidation activity. A rapid decrease of cellular cholesterol induced by intracellular expression of the split GFP-COase promoted the dissociation of a cholesterol biosensor D4H from the plasma membrane. The process was reversible as upon rapamycin removal, the split GFP-COase fluorescence was lost, and cellular cholesterol levels returned to normal. These data demonstrate that the split GFP-COase provides a novel tool to manipulate cholesterol in mammalian cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Cataplexy and monoamine oxidase deficiency in Norrie disease.

    Science.gov (United States)

    Vossler, D G; Wyler, A R; Wilkus, R J; Gardner-Walker, G; Vlcek, B W

    1996-05-01

    Norrie disease (ND) is an X-linked recessive disorder causing ocular atrophy, mental retardation, deafness, and dysmorphic features. Virtually absent monoamine oxidase (MAO) type-A and -B activity has been found in some boys with chromosome deletions. We report the coexistence of cataplexy and abnormal REM sleep organization with ND. Three related boys, referred for treatment of medically refractory atonic spells and apneas, underwent extended EEG-video-polysomnographic monitoring. They demonstrated attacks of cataplexy and inappropriate periods of REM sleep during which they were unarousable. One boy also had generalized tonic-clonic seizures. Previous testing revealed that all three have complete ND gene deletions. In all subjects, platelet MAO-B activity was absent, serum serotonin levels were markedly increased, and plasma catecholamine levels were normal. Data from the canine narcolepsy syndrome model implicate abnormal catecholaminergic and cholinergic activities in the pathogenesis of cataplexy. Our findings suggest that abnormal MAO activity or an imbalance between serotonin and other neurotransmitter levels may be involved in the pathogenesis of human cataplexy.

  6. Monoamine oxidase A (MAO A) inhibitors decrease glioma progression

    Science.gov (United States)

    Vaikari, Vijaya Pooja; Kota, Rajesh; Chen, Kevin; Yeh, Tzu-Shao; Jhaveri, Niyati; Groshen, Susan L.; Olenyuk, Bogdan Z.; Chen, Thomas C.; Hofman, Florence M.; Shih, Jean C.

    2016-01-01

    Glioblastoma (GBM) is an aggressive brain tumor which is currently treated with temozolomide (TMZ). Tumors usually become resistant to TMZ and recur; no effective therapy is then available. Monoamine Oxidase A (MAO A) oxidizes monoamine neurotransmitters resulting in reactive oxygen species which cause cancer. This study shows that MAO A expression is increased in human glioma tissues and cell lines. MAO A inhibitors, clorgyline or the near-infrared-dye MHI-148 conjugated to clorgyline (NMI), were cytotoxic for glioma and decreased invasion in vitro. Using the intracranial TMZ-resistant glioma model, clorgyline or NMI alone or in combination with low-dose TMZ reduced tumor growth and increased animal survival. NMI was localized specifically to the tumor. Immunocytochemistry studies showed that the MAO A inhibitor reduced proliferation, microvessel density and invasion, and increased macrophage infiltration. In conclusion, we have identified MAO A inhibitors as potential novel stand-alone drugs or as combination therapy with low dose TMZ for drug-resistant gliomas. NMI can also be used as a non-invasive imaging tool. Thus has a dual function for both therapy and diagnosis. PMID:26871599

  7. Spermine oxidase promotes bile canalicular lumen formation through acrolein production.

    Science.gov (United States)

    Uemura, Takeshi; Takasaka, Tomokazu; Igarashi, Kazuei; Ikegaya, Hiroshi

    2017-11-01

    Spermine oxidase (SMOX) catalyzes oxidation of spermine to generate spermidine, hydrogen peroxide (H 2 O 2 ) and 3-aminopropanal, which is spontaneously converted to acrolein. SMOX is induced by a variety of stimuli including bacterial infection, polyamine analogues and acetaldehyde exposure. However, the physiological functions of SMOX are not yet fully understood. We investigated the physiological role of SMOX in liver cells using human hepatocellular carcinoma cell line HepG2. SMOX localized to the bile canalicular lumen, as determined by F-actin staining. Knockdown of SMOX reduced the formation of bile canalicular lumen. We also found that phospho-Akt (phosphorylated protein kinase B) was localized to canalicular lumen. Treatment with Akt inhibitor significantly reduced the formation of bile canalicular lumen. Acrolein scavenger also inhibited the formation of bile canalicular lumen. PTEN, phosphatase and tensin homolog and an inhibitor of Akt, was alkylated in a SMOX-dependent manner. Our results suggest that SMOX plays a central role in the formation of bile canalicular lumen in liver cells by activating Akt pathway through acrolein production.

  8. Polyphenol Oxidase as a Biochemical Seed Defense Mechanism

    Directory of Open Access Journals (Sweden)

    E. Patrick Fuerst

    2014-12-01

    Full Text Available Seed dormancy and resistance to decay are fundamental survival strategies, which allow a population of seeds to germinate over long periods of time. Seeds have physical, chemical, and biological defense mechanisms that protect their food reserves from decay-inducing organisms and herbivores. Here, we hypothesize that seeds also possess enzyme-based biochemical defenses, based on induction of the plant defense enzyme, polyphenol oxidase (PPO, when wild oat (Avena fatua L. caryopses and seeds were challenged with seed-decaying Fusarium fungi. These studies suggest that dormant seeds are capable of mounting a defense response to pathogens. The pathogen-induced PPO activity from wild oat was attributed to a soluble isoform of the enzyme that appeared to result, at least in part, from proteolytic activation of a latent PPO isoform. PPO activity was also induced in wild oat hulls (lemma and palea, non-living tissues that cover and protect the caryopsis. These results are consistent with the hypothesis that seeds possess inducible enzyme-based biochemical defenses arrayed on the exterior of seeds and these defenses represent a fundamental mechanism of seed survival and longevity in the soil. Enzyme-based biochemical defenses may have broader implications since they may apply to other defense enzymes as well as to a diversity of plant species and ecosystems.

  9. Characterization of active site residues of nitroalkane oxidase.

    Science.gov (United States)

    Valley, Michael P; Fenny, Nana S; Ali, Shah R; Fitzpatrick, Paul F

    2010-06-01

    The flavoenzyme nitroalkane oxidase catalyzes the oxidation of primary and secondary nitroalkanes to the corresponding aldehydes and ketones plus nitrite. The structure of the enzyme shows that Ser171 forms a hydrogen bond to the flavin N5, suggesting that it plays a role in catalysis. Cys397 and Tyr398 were previously identified by chemical modification as potential active site residues. To more directly probe the roles of these residues, the S171A, S171V, S171T, C397S, and Y398F enzymes have been characterized with nitroethane as substrate. The C397S and Y398 enzymes were less stable than the wild-type enzyme, and the C397S enzyme routinely contained a substoichiometric amount of FAD. Analysis of the steady-state kinetic parameters for the mutant enzymes, including deuterium isotope effects, establishes that all of the mutations result in decreases in the rate constants for removal of the substrate proton by approximately 5-fold and decreases in the rate constant for product release of approximately 2-fold. Only the S171V and S171T mutations alter the rate constant for flavin oxidation. These results establish that these residues are not involved in catalysis, but rather are required for maintaining the protein structure. 2009 Elsevier Inc. All rights reserved.

  10. ABTS assay of phenol oxidase activity in soil.

    Science.gov (United States)

    Floch, Carine; Alarcon-Gutiérrez, Enrique; Criquet, Stéven

    2007-12-01

    Phenol oxidases (PO) are involved in degradation of many recalcitrant aromatic compounds and may be sensitive to some pollutants. Hence, their activities may be a useful indicator for evaluating soil quality and health. To this end, the aim of this study was to develop a simple method to assay PO activity directly in bulk samples by spectrophotometric test using 2,2'-azinobis-(-3 ethylbenzothiazoline-6-sulfononic acid) diammonium salt (ABTS) as the substrate. Three Mediterranean soils were used as models. For each soil, we studied the kinetic parameters and the effects of certain factors (i.e. amount of soil, pH, temperature, incubation time and substrate concentration) in order to determine the optimum conditions for the ABTS assay. Results showed that PO attain their optimum activities when incubating 0.1 g of soil at 30 degrees C for 5 min with 10 ml of a Modified Universal Buffer (MUB) at pH 2 and 200 microl of a 0.1 M ABTS solution.

  11. The NADPH oxidase inhibitor apocynin (acetovanillone) induces oxidative stress

    International Nuclear Information System (INIS)

    Riganti, Chiara; Costamagna, Costanzo; Bosia, Amalia; Ghigo, Dario

    2006-01-01

    Apocynin (acetovanillone) is often used as a specific inhibitor of NADPH oxidase. In N11 glial cells, apocynin induced, in a dose-dependent way, a significant increase of both malonyldialdehyde level (index of lipid peroxidation) and lactate dehydrogenase release (index of a cytotoxic effect). Apocynin evoked also, in a significant way, an increase of H 2 O 2 concentration and a decrease of the intracellular glutathione/glutathione disulfide ratio, accompanied by augmented efflux of glutathione and glutathione disulfide. Apocynin induced the activation of both pentose phosphate pathway and tricarboxylic acid cycle, which was blocked when the cells were incubated with glutathione together with apocynin. The cell incubation with glutathione prevented also the apocynin-induced increase of malonyldialdehyde generation and lactate dehydrogenase leakage. Apocynin exerted an oxidant effect also in a cell-free system: indeed, in aqueous solution, it evoked a faster oxidation of the thiols glutathione and dithiothreitol, and elicited the generation of reactive oxygen species, mainly superoxide anions. Our results suggest that apocynin per se can induce an oxidative stress and exert a cytotoxic effect in N11 cells and other cell types, and that some effects of apocynin in in vitro and in vivo experimental models should be interpreted with caution

  12. Xanthine oxidase activity regulates human embryonic brain cells growth

    Directory of Open Access Journals (Sweden)

    Kevorkian G. A.

    2011-10-01

    Full Text Available Aim. Involvement of Xanthine Oxidase (XO; EC1.1.3.22 in cellular proliferation and differentiation has been suggested by the numerous investigations. We have proposed that XO might have undoubtedly important role during the development, maturation as well as the death of human embryos brain cells. Methods. Human abortion material was utilized for the cultivation of brain cells (E90. XO activity was measured by the formation of uric acid in tissue. Cell death was detected by the utility of Trypan Blue dye. Results. Allopurinol suppressed the XO activity in the brain tissue (0.12 ± 0.02; 0.20 ± 0.03 resp., p < 0.05. On day 12th the number of cells in the culture treated with the Allopurinol at the early stage of development was higher in comparison with the Control (2350.1 ± 199.0 vs 2123 ± 96 and higher in comparison with the late period of treatment (1479.6 ± 103.8, p < < 0.05. In all groups, the number of the dead cells was less than in Control, indicating the protective nature of Allopurinol as an inhibitor of XO. Conclusions. Allopurinol initiates cells proliferation in case of the early treatment of the human brain derived cell culture whereas at the late stages it has an opposite effect.

  13. Reye's syndrome: salicylate and mitochondrial monoamine oxidase function

    International Nuclear Information System (INIS)

    Faraj, B.A.; Caplan, D.; Lolies, P.

    1986-01-01

    It has been suggested that aspirin is somehow linked with the onset of Reye's syndrome (RS). A general feature of Reye's syndrome is severe impairment of mitochondrial monoamine oxidase (MAO) function. The main objective of this investigation was to study the effect of salicylate on platelet mitochondrial MAO activity in three groups: group A (healthy children, n = 21) and group C (healthy adults, n = 10). Platelet MAO was measured by radio-enzymatic technique with 14 C-tyramine as a substrate. The results showed that salicyclate (10 mM) had a 20 to 60 percent inhibitory effect on platelet MAO function in only 1, 3 and 2 of the subjects in group A, B and C. Furthermore, there was an association between low enzyme activity and salicylate MAO inhibitory effect in these subjects. These preliminary findings suggest that salicylate may induce deterioration in mitochondrial function in susceptible individuals and that the assessment of salicylate MAO inhibitory effect may identify those who may be at risk to develop aspirin poisoning and Reye's syndrome

  14. Assays of D-Amino Acid Oxidase Activity

    Directory of Open Access Journals (Sweden)

    Elena Rosini

    2018-01-01

    Full Text Available D-amino acid oxidase (DAAO is a well-known flavoenzyme that catalyzes the oxidative FAD-dependent deamination of D-amino acids. As a result of the absolute stereoselectivity and broad substrate specificity, microbial DAAOs have been employed as industrial biocatalysts in the production of semi-synthetic cephalosporins and enantiomerically pure amino acids. Moreover, in mammals, DAAO is present in specific brain areas and degrades D-serine, an endogenous coagonist of the N-methyl-D-aspartate receptors (NMDARs. Dysregulation of D-serine metabolism due to an altered DAAO functionality is related to pathological NMDARs dysfunctions such as in amyotrophic lateral sclerosis and schizophrenia. In this protocol paper, we describe a variety of direct assays based on the determination of molecular oxygen consumption, reduction of alternative electron acceptors, or α-keto acid production, of coupled assays to detect the hydrogen peroxide or the ammonium production, and an indirect assay of the α-keto acid production based on a chemical derivatization. These analytical assays allow the determination of DAAO activity both on recombinant enzyme preparations, in cells, and in tissue samples.

  15. Selective inhibition of monoamine oxidase A by purpurin, an anthraquinone.

    Science.gov (United States)

    Lee, Hyun Woo; Ryu, Hyung Won; Kang, Myung-Gyun; Park, Daeui; Oh, Sei-Ryang; Kim, Hoon

    2017-03-01

    Monoamine oxidase (MAO) catalyzes the oxidation of monoamines that act as neurotransmitters. During a target-based screening of natural products using two isoforms of recombinant human MAO-A and MAO-B, purpurin (an anthraquinone derivative) was found to potently and selectively inhibit MAO-A, with an IC 50 value of 2.50μM, and not to inhibit MAO-B. Alizarin (also an anthraquinone) inhibited MAO-A less potently with an IC 50 value of 30.1μM. Furthermore, purpurin was a reversible and competitive inhibitor of MAO-A with a K i value of 0.422μM. A comparison of their chemical structures suggested the 4-hydroxy group of purpurin might play an important role in its inhibition of MAO-A. Molecular docking simulation showed that the binding affinity of purpurin for MAO-A (-40.0kcal/mol) was higher than its affinity for MAO-B (-33.9kcal/mol), and that Ile 207 and Gly 443 of MAO-A were key residues for hydrogen bonding with purpurin. The findings of this study suggest purpurin is a potent, selective, reversible inhibitor of MAO-A, and that it be considered a new potential lead compound for development of novel reversible inhibitors of MAO-A (RIMAs). Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Molecular evolution of the reactive oxygen-generating NADPH oxidase (Nox/Duox family of enzymes

    Directory of Open Access Journals (Sweden)

    Lambeth J David

    2007-07-01

    Full Text Available Abstract Background NADPH-oxidases (Nox and the related Dual oxidases (Duox play varied biological and pathological roles via regulated generation of reactive oxygen species (ROS. Members of the Nox/Duox family have been identified in a wide variety of organisms, including mammals, nematodes, fruit fly, green plants, fungi, and slime molds; however, little is known about the molecular evolutionary history of these enzymes. Results We assembled and analyzed the deduced amino acid sequences of 101 Nox/Duox orthologs from 25 species, including vertebrates, urochordates, echinoderms, insects, nematodes, fungi, slime mold amoeba, alga and plants. In contrast to ROS defense enzymes, such as superoxide dismutase and catalase that are present in prokaryotes, ROS-generating Nox/Duox orthologs only appeared later in evolution. Molecular taxonomy revealed seven distinct subfamilies of Noxes and Duoxes. The calcium-regulated orthologs representing 4 subfamilies diverged early and are the most widely distributed in biology. Subunit-regulated Noxes represent a second major subdivision, and appeared first in fungi and amoeba. Nox5 was lost in rodents, and Nox3, which functions in the inner ear in gravity perception, emerged the most recently, corresponding to full-time adaptation of vertebrates to land. The sea urchin Strongylocentrotus purpuratus possesses the earliest Nox2 co-ortholog of vertebrate Nox1, 2, and 3, while Nox4 first appeared somewhat later in urochordates. Comparison of evolutionary substitution rates demonstrates that Nox2, the regulatory subunits p47phox and p67phox, and Duox are more stringently conserved in vertebrates than other Noxes and Nox regulatory subunits. Amino acid sequence comparisons identified key catalytic or regulatory regions, as 68 residues were highly conserved among all Nox/Duox orthologs, and 14 of these were identical with those mutated in Nox2 in variants of X-linked chronic granulomatous disease. In addition to

  17. Construction of covalently attached enzyme multilayer films based on the photoreaction of diazo-resins and glucose oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Suxia [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 119 Jie Fang Road, Changchun 130023 (China); Niu Yaming [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 119 Jie Fang Road, Changchun 130023 (China); Sun Changqing [Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 119 Jie Fang Road, Changchun 130023 (China)]. E-mail: sunchq@mail.jlu.edu.cn

    2004-10-15

    A novel and facile approach to construct multilayered glucose oxidase (GOx) films on the surface of quartz or CaF{sub 2} slides as well as gold electrodes for use as biosensing interfaces is described. Diazo-resins (DAR) as polycation and glucose oxidase as polyanion were alternately deposited into a multilayer structure using layer-by-layer self-assembly technique based on electrostatic interaction as driving force. Upon near UV irradiation, the adjacent interfaces of the multilayer reacted to form a crosslinking structure which greatly improved the stability of the enzyme films. These changes was monitored and confirmed by UV-vis and IR spectroscopy. Ellipsometric measurements reveal that the enzymes formed sub-molecule layers, and the thickness of the film shows a linear relationship with the number of assembled layers, demonstrating a spatially well-ordered manner in multilayer structure. The covalently attached enzyme multilayer film has a highly permeable structure, and can be used as biosensing interface. Electrochemical and analytical behavior of the enzyme electrodes was studied by cyclic voltammetry (CV) in the presence or absence of glucose. The sensitivity of the enzyme-modified electrodes was estimated through the analysis of voltammetric signals, which can be fine turned to the desired level by adjusting the number of attached bilayers.

  18. Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of variants of monoamine oxidase from Aspergillus niger

    Energy Technology Data Exchange (ETDEWEB)

    Atkin, Kate E. [Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW (United Kingdom); Reiss, Renate; Turner, Nicholas J. [School of Chemistry, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN (United Kingdom); Brzozowski, Andrzej M.; Grogan, Gideon, E-mail: grogan@ysbl.york.ac.uk [Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW (United Kingdom)

    2008-03-01

    Crystals of A. niger monoamine oxidase variants display P2{sub 1} or P4{sub 1}2{sub 1}2/P4{sub 3}2{sub 1}2 symmetry, with eight or two molecules in the asymmetric unit, respectively. Monoamine oxidase from Aspergillus niger (MAO-N) is an FAD-dependent enzyme that catalyses the conversion of terminal amines to their corresponding aldehydes. Variants of MAO-N produced by directed evolution have been shown to possess altered substrate specificity. Crystals of two of these variants (MAO-N-3 and MAO-N-5) have been obtained; the former displays P2{sub 1} symmetry with eight molecules per asymmetric unit and the latter has P4{sub 1}2{sub 1}2 or P4{sub 3}2{sub 1}2 symmetry and two molecules per asymmetric unit. Solution of these structures will help shed light on the molecular determinants of improved activity and high enantioselectivity towards a broad range of substrates.

  19. Construction of covalently attached enzyme multilayer films based on the photoreaction of diazo-resins and glucose oxidase

    International Nuclear Information System (INIS)

    Zhang Suxia; Niu Yaming; Sun Changqing

    2004-01-01

    A novel and facile approach to construct multilayered glucose oxidase (GOx) films on the surface of quartz or CaF 2 slides as well as gold electrodes for use as biosensing interfaces is described. Diazo-resins (DAR) as polycation and glucose oxidase as polyanion were alternately deposited into a multilayer structure using layer-by-layer self-assembly technique based on electrostatic interaction as driving force. Upon near UV irradiation, the adjacent interfaces of the multilayer reacted to form a crosslinking structure which greatly improved the stability of the enzyme films. These changes was monitored and confirmed by UV-vis and IR spectroscopy. Ellipsometric measurements reveal that the enzymes formed sub-molecule layers, and the thickness of the film shows a linear relationship with the number of assembled layers, demonstrating a spatially well-ordered manner in multilayer structure. The covalently attached enzyme multilayer film has a highly permeable structure, and can be used as biosensing interface. Electrochemical and analytical behavior of the enzyme electrodes was studied by cyclic voltammetry (CV) in the presence or absence of glucose. The sensitivity of the enzyme-modified electrodes was estimated through the analysis of voltammetric signals, which can be fine turned to the desired level by adjusting the number of attached bilayers

  20. In Vivo Metabolic Trapping Radiotracers for Imaging Monoamine Oxidase-A and –B Enzymatic Activity

    Science.gov (United States)

    Brooks, Allen F.; Shao, Xia; Quesada, Carole A.; Sherman, Phillip; Scott, Peter J.H.; Kilbourn, Michael R.

    2017-01-01

    The isozymes of monoamine oxidase (MAO-A and MAO-B) are important enzymes involved in the metabolism of numerous biogenic amines, including the neurotransmitters serotonin, dopamine and norepinephrine. Recently, changes in concentrations of MAO-B have been proposed as an in vivo marker of neuroinflammation associated with Alzheimer’s disease. Previous developments of in vivo radiotracers for imaging changes in MAO enzyme expression or activity have utilized the irreversible propargylamine-based suicide inhibitors, or high-affinity reversibly-binding inhibitors. As an alternative approach, we have investigated 1-[11C]methyl-4-aryloxy-1,2,3,6-tetrahydropyridines as metabolic trapping agents for the monoamine oxidases. MAO-mediated oxidation and spontaneous hydrolysis yields 1-[11C]methyl-2,3-dihydro-4-pyridinone as a hydrophilic metabolite that is trapped within brain tissues. Radiotracers with phenyl, biphenyl and 7-coumarinyl ethers were evaluated using microPET imaging in rat and primate brain. No isozyme selectivity for radiotracer trapping was observed in the rat brain for any compound, but in the monkey brain the phenyl ether demonstrated MAO-A selectivity, and the coumarinyl ether showed MAO-B selectivity. These are lead compounds for further development of 1-[11C]methyl-4-aryloxy-1,2,3,6-tetrahydropyridines with optimized brain pharmacokinetics and isozyme selectivity. PMID:26393369

  1. NADPH Oxidase 1 Modulates WNT and NOTCH1 Signaling To Control the Fate of Proliferative Progenitor Cells in the Colon▿

    Science.gov (United States)

    Coant, Nicolas; Ben Mkaddem, Sanae; Pedruzzi, Eric; Guichard, Cécile; Tréton, Xavier; Ducroc, Robert; Freund, Jean-Noel; Cazals-Hatem, Dominique; Bouhnik, Yoram; Woerther, Paul-Louis; Skurnik, David; Grodet, Alain; Fay, Michèle; Biard, Denis; Lesuffleur, Thécla; Deffert, Christine; Moreau, Richard; Groyer, André; Krause, Karl-Heinz; Daniel, Fanny; Ogier-Denis, Eric

    2010-01-01

    The homeostatic self-renewal of the colonic epithelium requires coordinated regulation of the canonical Wnt/β-catenin and Notch signaling pathways to control proliferation and lineage commitment of multipotent stem cells. However, the molecular mechanisms by which the Wnt/β-catenin and Notch1 pathways interplay in controlling cell proliferation and fate in the colon are poorly understood. Here we show that NADPH oxidase 1 (NOX1), a reactive oxygen species (ROS)-producing oxidase that is highly expressed in colonic epithelial cells, is a pivotal determinant of cell proliferation and fate that integrates Wnt/β-catenin and Notch1 signals. NOX1-deficient mice reveal a massive conversion of progenitor cells into postmitotic goblet cells at the cost of colonocytes due to the concerted repression of phosphatidylinositol 3-kinase (PI3K)/AKT/Wnt/β-catenin and Notch1 signaling. This conversion correlates with the following: (i) the redox-dependent activation of the dual phosphatase PTEN, causing the inactivation of the Wnt pathway effector β-catenin, and (ii) the downregulation of Notch1 signaling that provokes derepression of mouse atonal homolog 1 (Math1) expression. We conclude that NOX1 controls the balance between goblet and absorptive cell types in the colon by coordinately modulating PI3K/AKT/Wnt/β-catenin and Notch1 signaling. This finding provides the molecular basis for the role of NOX1 in cell proliferation and postmitotic differentiation. PMID:20351171

  2. Dual oxidase maturation factor 1 (DUOXA1) overexpression increases reactive oxygen species production and inhibits murine muscle satellite cell differentiation.

    Science.gov (United States)

    Sandiford, Shelley D E; Kennedy, Karen A M; Xie, Xiaojun; Pickering, J Geoffrey; Li, Shawn S C

    2014-01-11

    Dual oxidase maturation factor 1 (DUOXA1) has been associated with the maturation of the reactive oxygen species (ROS) producing enzyme, dual oxidase 1 (DUOX1) in the adult thyroid. However, ROS have also been implicated in the development of several tissues. We found that activated muscle satellite cells and primary myoblasts isolated from mice express robust levels of DUOXA1 and that its levels are altered as cells differentiate. To determine whether DUOXA1 levels affect muscle differentiation, we used an adenoviral construct (pCMV5-DUOXA1-GFP) to drive constitutive overexpression of this protein in primary myoblasts. High levels of DUOXA1 throughout myogenesis resulted in enhanced H2O2 production, fusion defects, reduced expression of early (myogenin) and late (myosin heavy chain) markers of differentiation, and elevated levels of apoptosis compared to control cells infected with an empty adenoviral vector (pCMV5-GFP). DUOXA1 knockdown (using a DUOXA1 shRNA construct) resulted in enhanced differentiation compared to cells subjected to a control shRNA, and subjecting DUOXA1 overexpressing cells to siRNAs targeting DUOX1 or apoptosis signal-regulating kinase 1 (ASK1) rescued the phenotype. This study represents the first to demonstrate the importance of DUOXA1 in skeletal muscle myoblasts and that DUOXA1 overexpression in muscle stem cells induces apoptosis and inhibits differentiation through DUOX1 and ASK1.

  3. A novel L-amino acid oxidase from Trichoderma harzianum ETS 323 associated with antagonism of Rhizoctonia solani.

    Science.gov (United States)

    Yang, Chia-Ann; Cheng, Chi-Hua; Lo, Chaur-Tsuen; Liu, Shu-Ying; Lee, Jeng-Woei; Peng, Kou-Cheng

    2011-05-11

    Trichoderma spp. are used as biocontrol agents against phytopathogens such as Rhizoctonia solani, but their biocontrol mechanisms are poorly understood. A novel L-amino oxidase (Th-LAAO) was identified from the extracellular proteins of Trichoderma harzianum ETS 323. Here, we show a FAD-binding glycoprotein with the best substrate specificity constant for L-phenylalanine. Although the amino acid sequence of Th-LAAO revealed limited homology (16-24%) to other LAAO members, a highly conserved FAD-binding motif was identified in the N-terminus. Th-LAAO was shown to be a homodimeric protein, but the monomeric form was predominant when grown in the presence of deactivated Rhizoctonia solani. Furthermore, in vitro assays demonstrated that Th-LAAO had an antagonistic effect against Rhizoctonia solani and a stimulatory one on hyphal density and sporulation in T. harzianum ETS 323. These findings further our understanding of T. harzianum as a biocontrol agent and provide insight into the biological function of l-amino acid oxidase.

  4. Design of carbon nanotube-based gas-diffusion cathode for O{sub 2} reduction by multicopper oxidases

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Carolin; Adkins, Emily R.; Atanassov, Plamen [University of New Mexico, Center for Emerging Energy Technologies, Albuquerque, NM (United States); Ramasamy, Ramaraja P. [Microbiology and Applied Biochemistry, Airbase Sciences, Air Force Research Laboratory, Tyndall Air Force Base, FL (United States); Nano-Electrochemistry Laboratory, Faculty of Engineering, University of Georgia, Athens, GA (United States); Luckarift, Heather R.; Johnson, Glenn R. [Microbiology and Applied Biochemistry, Airbase Sciences, Air Force Research Laboratory, Tyndall Air Force Base, FL (United States)

    2012-01-15

    Multicopper oxidases, such as laccase or bilirubin oxidase, are known to reduce molecular oxygen at very high redox potentials, which makes them attractive biocatalysts for enzymatic cathodes in biological fuel cells. By designing an enzymatic gas-diffusion electrode, molecular oxygen can be supplied through the gaseous phase, avoiding solubility and diffusion limitations typically associated with liquid electrolytes. In doing so, the current density of enzymatic cathodes can theoretically be enhanced. This publication presents a material study of carbon/Teflon composites that aim to optimize the functionality of the gas-diffusion and catalytic layers for application in enzymatic systems. The modification of the catalytic layer with multiwalled carbon nanotubes, for example, creates the basis for stronger {pi}-{pi} stacking interactions through tethered enzymatic linkers, such as pyrenes or perylene derivates. Cyclic voltammograms show the effective direct electron contact of laccase with carbon nanotube-modified electrodes via tethered crosslinking molecules as a model system. The polarization behavior of laccase-modified gas-diffusion electrodes reveals open-circuit potentials of +550 mV (versus Ag/AgCl) and current densities approaching 0.5 mA cm{sup 2} (at zero potential) in air-breathing mode. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Loss of the smallest subunit of cytochrome c oxidase, COX8A, causes Leigh-like syndrome and epilepsy.

    Science.gov (United States)

    Hallmann, Kerstin; Kudin, Alexei P; Zsurka, Gábor; Kornblum, Cornelia; Reimann, Jens; Stüve, Burkhard; Waltz, Stephan; Hattingen, Elke; Thiele, Holger; Nürnberg, Peter; Rüb, Cornelia; Voos, Wolfgang; Kopatz, Jens; Neumann, Harald; Kunz, Wolfram S

    2016-02-01

    Isolated cytochrome c oxidase (complex IV) deficiency is one of the most frequent respiratory chain defects in humans and is usually caused by mutations in proteins required for assembly of the complex. Mutations in nuclear-encoded structural subunits are very rare. In a patient with Leigh-like syndrome presenting with leukodystrophy and severe epilepsy, we identified a homozygous splice site mutation in COX8A, which codes for the ubiquitously expressed isoform of subunit VIII, the smallest nuclear-encoded subunit of complex IV. The mutation, affecting the last nucleotide of intron 1, leads to aberrant splicing, a frame-shift in the highly conserved exon 2, and decreased amount of the COX8A transcript. The loss of the wild-type COX8A protein severely impairs the stability of the entire cytochrome c oxidase enzyme complex and manifests in isolated complex IV deficiency in skeletal muscle and fibroblasts, similar to the frequent c.845_846delCT mutation in the assembly factor SURF1 gene. Stability and activity of complex IV could be rescued in the patient's fibroblasts by lentiviral expression of wild-type COX8A. Our findings demonstrate that COX8A is indispensable for function of human complex IV and its mutation causes human disease. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Pretreatment with mixed-function oxidase inducers increases the sensitivity of the hepatocyte/DNA repair assay

    International Nuclear Information System (INIS)

    Shaddock, J.G.; Heflich, R.H.; McMillan, D.C.; Hinson, J.A.; Casciano, D.A.

    1989-01-01

    A recent National Toxicology Program evaluation indicates that the rat hepatocyte/DNA repair assay has a high false-negative rate and that it is insensitive to some genotoxic hepatocarcinogens as well as other species and organ-specific carcinogens. In this study, the authors examined whether the sensitivity of the hepatocyte/DNA repair assay might be increased through animal pretreatment with various hepatic mixed-function oxidase inducers, i.e., Aroclor 1254, phenobarbital, and 3,3',4,4'-tetrachloroazobenzene (TCAB). The effects on unscheduled DNA synthesis (UDS), a measured of DNA damage and repair, were studied in cultures exposed to known and/or potential carcinogens that had been evaluated as negative or questionable or that produced conflicting results with hepatocytes isolated from uninduced animals. 4,4'-Oxydianiline, 1-nitropy-rene, and TCAB produced concentration-dependent increases in UDS in hepatocytes from rats pretreated with Aroclor 1254. 4,4'-Oxydianiline and TCAB also induced a dose-dependent increase in DNA repair in hepatocytes from rats pretreated with phenobarbital, whereas 1-nitropyrene was negative. These data indicate that the limited sensitivity to chemical carcinogens displayed by the hepatocyte/DNA repair assay may be increased by using hepatocytes isolated from animals exposed to hepatic mixed-function oxidase inducers

  7. Pretreatment with mixed-function oxidase inducers increases the sensitivity of the hepatocyte/DNA repair assay

    Energy Technology Data Exchange (ETDEWEB)

    Shaddock, J.G.; Heflich, R.H.; McMillan, D.C.; Hinson, J.A.; Casciano, D.A. (National Center for Toxicological Research, Jefferson, AK (USA) Univ. of Arkansas for Medical Sciences, Little Rock (USA))

    1989-01-01

    A recent National Toxicology Program evaluation indicates that the rat hepatocyte/DNA repair assay has a high false-negative rate and that it is insensitive to some genotoxic hepatocarcinogens as well as other species and organ-specific carcinogens. In this study, the authors examined whether the sensitivity of the hepatocyte/DNA repair assay might be increased through animal pretreatment with various hepatic mixed-function oxidase inducers, i.e., Aroclor 1254, phenobarbital, and 3,3{prime},4,4{prime}-tetrachloroazobenzene (TCAB). The effects on unscheduled DNA synthesis (UDS), a measured of DNA damage and repair, were studied in cultures exposed to known and/or potential carcinogens that had been evaluated as negative or questionable or that produced conflicting results with hepatocytes isolated from uninduced animals. 4,4{prime}-Oxydianiline, 1-nitropy-rene, and TCAB produced concentration-dependent increases in UDS in hepatocytes from rats pretreated with Aroclor 1254. 4,4{prime}-Oxydianiline and TCAB also induced a dose-dependent increase in DNA repair in hepatocytes from rats pretreated with phenobarbital, whereas 1-nitropyrene was negative. These data indicate that the limited sensitivity to chemical carcinogens displayed by the hepatocyte/DNA repair assay may be increased by using hepatocytes isolated from animals exposed to hepatic mixed-function oxidase inducers.

  8. Relationship between CNS metabolism and cytoarchitecture: a review of 14C-deoxyglucose studies with correlation to cytochrome oxidase histochemistry

    International Nuclear Information System (INIS)

    Di Rocco, R.J.; Kageyama, G.H.; Wong-Riley, M.T.

    1989-01-01

    Since the inception of the 14 C-deoxyglucose method and its extension to in vivo imaging of regional cerebral glucose metabolism in humans by positron emission tomography, uncertainty has persisted concerning the type of work to which regional metabolism is coupled, as well as the distribution of this work within the neuron. 14 C-deoxyglucose studies indicate that functionally-coupled neural metabolism is more apparent in axon terminals and perhaps dendrites than neuronal perikarya. Moreover, it appears that most of the metabolism in axon terminals is accounted for by Na+-K+-ATPase activity. Nevertheless, cytochrome oxidase histochemistry reveals the presence of intensely reactive mitochondria in soma-dendrite regions opposite presynaptic axon terminals, thereby indicating that continuous temporal and spatial summation of postsynaptic graded potentials is associated with increased metabolism. While the situation concerning the relative postsynaptic metabolic prices of EPSP's and IPSP's remains uncertain, the presence of elevated levels of cytochrome oxidase activity within certain classes of presynaptic terminals indicates that active excitation and inhibition is associated with increases in presynaptic metabolism. This observation has been confirmed in 14 C-deoxyglucose studies. Nevertheless, studies of neonatal hippocampus indicate that, before metabolic activity shifts to dendritic and telodendritic regions of electrophysiological activity, metabolism is high in somal foci of biosynthesis. 51 references

  9. Glucose biosensor based on glucose oxidase immobilized at gold nanoparticles decorated graphene-carbon nanotubes.

    Science.gov (United States)

    Devasenathipathy, Rajkumar; Mani, Veerappan; Chen, Shen-Ming; Huang, Sheng-Tung; Huang, Tsung-Tao; Lin, Chun-Mao; Hwa, Kuo-Yuan; Chen, Ting-Yo; Chen, Bo-Jun

    2015-10-01

    Biopolymer pectin stabilized gold nanoparticles were prepared at graphene and multiwalled carbon nanotubes (GR-MWNTs/AuNPs) and employed for the determination of glucose. The formation of GR-MWNTs/AuNPs was confirmed by scanning electron microscopy, X-ray diffraction, UV-vis and FTIR spectroscopy methods. Glucose oxidase (GOx) was successfully immobilized on GR-MWNTs/AuNPs film and direct electron transfer of GOx was investigated. GOx exhibits highly enhanced redox peaks with formal potential of -0.40 V (vs. Ag/AgCl). The amount of electroactive GOx and electron transfer rate constant were found to be 10.5 × 10(-10) mol cm(-2) and 3.36 s(-1), respectively, which were significantly larger than the previous reports. The fabricated amperometric glucose biosensor sensitively detects glucose and showed two linear ranges: (1) 10 μM - 2 mM with LOD of 4.1 μM, (2) 2 mM - 5.2 mM with LOD of 0.95 mM. The comparison of the biosensor performance with reported sensors reveals the significant improvement in overall sensor performance. Moreover, the biosensor exhibited appreciable stability, repeatability, reproducibility and practicality. The other advantages of the fabricated biosensor are simple and green fabrication approach, roughed and stable electrode surface, fast in sensing and highly reproducible. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Glucose impairs aspirin inhibition in platelets through a NAD(P)H oxidase signaling pathway.

    Science.gov (United States)

    Kobzar, Gennadi; Mardla, Vilja; Samel, Nigulas

    2017-07-01

    Hyperglycemia has been suggested to play a role in the increased platelet resistance to antiplatelet therapy in patients with diabetes mellitus. Exposure to high glucose impairs platelet inhibition by aspirin. It has been found that antioxidant agents reduce the effect of glucose, confirming the involvement of reactive oxygen species (ROS) in the effect of glucose. The aim of the study was to examine the mechanism of ROS increase by high glucose in aspirin-treated platelets. Platelet aggregation was measured by the optical method, and the production of ROS was detected using luminol-dependent horseradish peroxidase-enhanced chemiluminescence. We found that glucose did not affect ADP-induced platelet aggregation. However, it reduced the effect of aspirin on platelet aggregation, which was accompanied by an increase in ROS generation. The inhibition of NAD(P)H oxidase (NOX) prevented the glucose effect and ROS generation. The same result was recorded after the inhibition of p38 mitogen-activated protein kinases (p38 MAPK), phospholipase A 2 (PLA 2 ) or 12-lipoxygenase (12-LOX). The inhibition of TxA 2 receptor did not decrease the effect of glucose indicating that the effect was not caused by activation of TxA 2 receptors. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. A glucose biosensor based on glucose oxidase immobilized on three-dimensional porous carbon electrodes.

    Science.gov (United States)

    Chen, Jingyi; Zhu, Rong; Huang, Jia; Zhang, Man; Liu, Hongyu; Sun, Min; Wang, Li; Song, Yonghai

    2015-08-21

    A novel glucose biosensor was developed by immobilizing glucose oxidase (GOD) on a three-dimensional (3D) porous kenaf stem-derived carbon (3D-KSC) which was firstly proposed as a novel supporting material to load biomolecules for electrochemical biosensing. Here, an integrated 3D-KSC electrode was prepared by using a whole piece of 3D-KSC to load the GOD molecules for glucose biosensing. The morphologies of integrated 3D-KSC and 3D-KSC/GOD electrodes were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM results revealed a 3D honeycomb macroporous structure of the integrated 3D-KSC electrode. The TEM results showed some microporosities and defects in the 3D-KSC electrode. The electrochemical behaviors and electrocatalytic performance of the integrated 3D-KSC/GOD electrode were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The effects of pH and scan rates on the electrochemical response of the biosensor have been studied in detail. The glucose biosensor showed a wide linear range from 0.1 mM to 14.0 mM with a high sensitivity of 1.73 μA mM(-1) and a low detection limit of 50.75 μM. Furthermore, the glucose biosensor exhibited high selectivity, good repeatability and reproducibility, and good stability.

  12. Radiosynthesis of [11C]brofaromine, a potential tracer for imaging monoamine oxidase A

    International Nuclear Information System (INIS)

    Ametamey, S.M.; Beer, H.-F.; Guenther, I.; Antonini, A.; Leenders, K.L.; Waldmeier, P.C.; Schubiger, P.A.

    1996-01-01

    Brofaromine(4-5(-methoxy-7-bromobenzofuranyl)-2-piperidine-HCl) is a potent and selective inhibitor of monoamine oxidase (MAO) A. Two methods for its synthesis and a preliminary positron emission tomography (PET) evaluation in monkey brain are described. The first method, at low carrier concentration of CO 2 , consisted of direct O-methylation of (4-(5-hydroxy-7-bromobenzofuranyl)-2-piperidine). The total radiochemical yield achieved ranged from 30 to 50% (from end of bombardment [EOB] and decay corrected) with an overall synthesis time of 45 min. The second approach, with high carrier amounts of CO 2 arising from inherent target problems, was accomplished in a three-step route involving protection of secondary amino functionality, O-methylation and deprotection. The total radiochemical yield was 10% (from EOB and decay corrected) with a total synthesis time of 70 min. For both methods methylation was achieved using the classical methylating agent [ 11 C]CH 3 I, and radiochemical purity was higher than 98%. PET evaluation of the radioligand in a Rhesus monkey showed a high uptake of radioactivity in the brain. Using the irreversible MAO-A inhibitor clorgyline and reversible MAO-A inhibitors moclobemide and brofaromine, three blockade experiments were designed to determine the extent of specific binding of [ 11 C]brofaromine to MAO-A. No apparent decrease in accumulation of radioactivity in the monkey brain was observed when compared to a baseline scan

  13. Lead-elevated activity of xanthine oxidase in lead-exposed workers

    Directory of Open Access Journals (Sweden)

    Sławomir Kasperczyk

    2013-04-01

    Full Text Available Background: The aim of the present study was to explore the connection between lead toxicity and the activity of xanthine oxidase (XO. In addition, we indicated the uric acid (UA and creatinine levels and concentration of erythrocyte malondialdehyde (MDA to estimate oxidative stress intensity. Materials and Methods: The examined group consisted of 125 healthy male employees of zinc and lead works. The examined group was divided into tertiles according to blood lead levels. In the collected blood samples, concentrations of lead-exposure indices, UA, creatinine, and MDA as well as activity of XO were measured concomitantly. The control group consisted of 32 healthy male administrative workers who were exposed to lead only environmentally. Results: XO activity and MDA level were significantly elevated in all tertiles compared to the control group. Creatinine level was significantly elevated in the medium and high tertiles. However, the level of UA was significantly elevated in the high tertile, while in the low and medium tertile only a tendency toward higher values was observed. Conclusions: Occupational exposure to lead induces activity of XO. This induction may contribute to the observed simultaneously increased oxidative stress, measured as MDA level, and the increased level of UA. Med Pr 2013;64(2:175–180

  14. Glucose oxidase/cellulose-carbon nanotube composite paper as a biocompatible bioelectrode for biofuel cells.

    Science.gov (United States)

    Won, Keehoon; Kim, Young-Hoo; An, Seulji; Lee, Hye Jung; Park, Saerom; Choi, Yong-Keun; Kim, Ji Hyeon; Hwang, Hak-In; Kim, Hyung Joo; Kim, Hyungsup; Lee, Sang Hyun

    2013-11-01

    Biofuel cells are devices for generating electrical energy directly from chemical energy of renewable biomass using biocatalysts such as enzymes. Efficient electrical communication between redox enzymes and electrodes is essential for enzymatic biofuel cells. Carbon nanotubes (CNTs) have been recognized as ideal electrode materials because of their high electrical conductivity, large surface area, and inertness. Electrodes consisting entirely of CNTs, which are known as CNT paper, have high surface areas but are typically weak in mechanical strength. In this study, cellulose (CL)-CNT composite paper was fabricated as electrodes for enzymatic biofuel cells. This composite electrode was prepared by vacuum filtration of CNTs followed by reconstitution of cellulose dissolved in ionic liquid, 1-ethyl-3-methylimidazolium acetate. Glucose oxidase (GOx), which is a redox enzyme capable of oxidizing glucose as a renewable fuel using oxygen, was immobilized on the CL-CNT composite paper. Cyclic voltammograms revealed that the GOx/CL-CNT paper electrode showed a pair of well-defined peaks, which agreed well with that of FAD/FADH2, the redox center of GOx. This result clearly shows that the direct electron transfer (DET) between the GOx and the composite electrode was achieved. However, this DET was dependent on the type of CNTs. It was also found that the GOx immobilized on the composite electrode retained catalytic activity for the oxidation of glucose.

  15. Evaluation of serum lysyl oxidase as a blood test for colorectal cancer.

    Science.gov (United States)

    Ward, S T; Weston, C J; Hepburn, E; Damery, S; Hejmadi, R K; Morton, D G; Middleton, G; Ismail, T; Adams, D H

    2014-06-01

    Lysyl oxidase (LOX) expression is elevated in colorectal cancer (CRC) tissue and associated with disease progression. A blood test may form a more acceptable diagnostic test for CRC although LOX has not previously been measured in the serum. We therefore sought to determine the clinical usefulness of a serum LOX test for CRC in a symptomatic population. Adult patients referred to a hospital colorectal clinic with bowel symptoms completed a questionnaire and provided a blood sample for serum LOX measurement. Associations between presenting symptoms, serum LOX concentrations and outcomes of investigations were tested by univariate and multivariate analyses to determine if serum LOX was clinically useful in the prediction of CRC. LOX expression in CRC and adjacent colon biopsies was evaluated by ELISA and immunohistochemistry. Thirty-one cases of colorectal cancer and 16 high-risk polyps were identified from a total of 962 participants. There was no association between serum LOX concentration and the presence of CRC, high-risk polyps or cancers at any site. LOX expression was significantly increased in CRC tissue compared to adjacent colon. Despite overexpression of LOX in CRC tissue, elevated serum levels could not be demonstrated. Serum LOX measurement is therefore not a clinically useful test for CRC. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Radio-isotopic determination of platelet monoamine oxidase and regulation of its activity by an indigenous drug

    International Nuclear Information System (INIS)

    Dubey, G.P.; Srivastava, V.K.; Agrawal, A.; Udupa, K.N.

    1988-01-01

    Platelet monoamine oxidase is a mitochondrial enzyme taking part in the deamination reaction of total catecholamine. Recent studies of monoamine oxidase inhibitors have gained its importance in the control of variety of psychosomatic disorders like mental depression, arterial hypertension and anxiety neurosis. 30 apparently normal individuals and 42 diagnosed cases of essential hypertension were selected for the present study. The platelet monoamine oxidase activity was measured by using 14 C-tryptamine bisuccinate. Comparatively low activity of platelet monoamine oxidase was noticed in hypertension cases than in the normal. After oral administration of an indigenous drug 'Geriforte' for three months, a significant rise in platelet monoamine oxidase activity was noticed in hypertension cases. It can be concluded that this indigenous formulation has the capacity to regulate the monoamine oxidase activity, as such, it may provide an alternative remedy in the management of psychosomatic disorders. (author). 11 refs

  17. Biofabrication Using Pyrrole Electropolymerization for the Immobilization of Glucose Oxidase and Lactate Oxidase on Implanted Microfabricated Biotransducers

    Directory of Open Access Journals (Sweden)

    Christian N. Kotanen

    2014-03-01

    Full Text Available The dual responsive Electrochemical Cell-on-a-Chip Microdisc Electrode Array (ECC MDEA 5037 is a recently developed electrochemical transducer for use in a wireless, implantable biosensor system for the continuous measurement of interstitial glucose and lactate. Fabrication of the biorecognition membrane via pyrrole electropolymerization and both in vitro and in vivo characterization of the resulting biotransducer is described. The influence of EDC-NHS covalent conjugation of glucose oxidase with 4-(3-pyrrolyl butyric acid (monomerization and with 4-sulfobenzoic acid (sulfonization on biosensor performance was examined. As the extent of enzyme conjugation was increased sensitivity decreased for monomerized enzymes but increased for sulfonized enzymes. Implanted biotransducers were examined in a Sprague-Dawley rat hemorrhage model. Resection after 4 h and subsequent in vitro re-characterization showed a decreased sensitivity from 0.68 (±0.40 to 0.22 (±0.17 µA·cm−2·mM−1, an increase in the limit of detection from 0.05 (±0.03 to 0.27 (±0.27 mM and a six-fold increase in the response time from 41 (±18 to 244 (±193 s. This evidence reconfirms the importance of biofouling at the bio-abio interface and the need for mitigation strategies to address the foreign body response.

  18. Interactions of Desmethoxyyangonin, a Secondary Metabolite from Renealmia alpinia, with Human Monoamine Oxidase-A and Oxidase-B

    Directory of Open Access Journals (Sweden)

    Narayan D. Chaurasiya

    2017-01-01

    Full Text Available Renealmia alpinia (Zingiberaceae, a medicinal plant of tropical rainforests, is used to treat snakebites and other injuries and also as a febrifuge, analgesic, antiemetic, antiulcer, and anticonvulsant. The dichloromethane extract of R. alpinia leaves showed potent inhibition of human monoamine oxidases- (MAOs- A and B. Phytochemical studies yielded six known compounds, including pinostrobin 1, 4′-methyl ether sakuranetin 2, sakuranetin 3, pinostrobin chalcone 4, yashabushidiol A 5, and desmethoxyyangonin 6. Compound 6 displayed about 30-fold higher affinity for MAO-B than MAO-A, with Ki values of 31 and 922 nM, respectively. Kinetic analysis of inhibition and equilibrium-dialysis dissociation assay of the enzyme-inhibitor complex showed reversible binding of desmethoxyyangonin 6 with MAO-A and MAO-B. The binding interactions of compound 6 in the active site of the MAO-A and MAO-B isoenzymes, investigated through molecular modeling algorithms, confirmed preferential binding of desmethoxyyangonin 6 with MAO-B compared to MAO-A. Selective reversible inhibitors of MAO-B, like desmethoxyyangonin 6, may have important therapeutic significance for the treatment of neurodegenerative disorders, such as Parkinson’s disease and Alzheimer’s disease.

  19. Presteady-state and steady-state kinetic properties of human cytochrome c oxidase. Identification of rate-limiting steps in mammalian cytochrome c oxidase

    NARCIS (Netherlands)

    van Kuilenburg, A. B.; Gorren, A. C.; Dekker, H. L.; Nieboer, P.; van Gelder, B. F.; Muijsers, A. O.

    1992-01-01

    Human cytochrome c oxidase was purified in a fully active form from heart and skeletal muscle. The enzyme was selectively solubilised with octylglucoside and KCl from submitochondrial particles followed by ammonium sulphate fractionation. The presteady-state and steady-state kinetic properties of

  20. A point mutation of valine-311 to methionine in Bacillus subtilis protoporphyrinogen oxidase does not greatly increase resistance to the diphenyl ether herbicide oxyfluorfen.

    Science.gov (United States)

    Jeong, Eunjoo; Houn, Thavrak; Kuk, Yongin; Kim, Eun-Seon; Chandru, Hema Kumar; Baik, Myunggi; Back, Kyoungwhan; Guh, Ja-Ock; Han, Oksoo

    2003-10-01

    In an effort to asses the effect of Val311Met point mutation of Bacillus subtilis protoporphyrinogen oxidase on the resistance to diphenyl ether herbicides, a Val311Met point mutant of B. subtilis protoporphyrinogen oxidase was prepared, heterologously expressed in Escherichia coli, and the purified recombinant Val311Met mutant protoporphyrinogen oxidase was kinetically characterized. The mutant protoporphyrinogen oxidase showed very similar kinetic patterns to wild type protoporphyrinogen oxidase, with slightly decreased activity dependent on pH and the concentrations of NaCl, Tween 20, and imidazole. When oxyfluorfen was used as a competitive inhibitor, the Val311Met mutant protoporphyrinogen oxidase showed an increased inhibition constant about 1.5 times that of wild type protoporphyrinogen oxidase. The marginal increase of the inhibition constant indicates that the Val311Met point mutation in B. subtilis protoporphyrinogen oxidase may not be an important determinant in the mechanism that protects protoporphyrinogen oxidase against diphenyl ether herbicides.

  1. Novel multifunctional neuroprotective iron chelator-monoamine oxidase inhibitor drugs for neurodegenerative diseases: in vitro studies on antioxidant activity, prevention of lipid peroxide formation and monoamine oxidase inhibition.

    Science.gov (United States)

    Zheng, Hailin; Gal, Shunit; Weiner, Lev M; Bar-Am, Orit; Warshawsky, Abraham; Fridkin, Mati; Youdim, Moussa B H

    2005-10-01

    Iron-dependent oxidative stress, elevated levels of iron and of monoamine oxidase (MAO)-B activity, and depletion of antioxidants in the brain may be major pathogenic factors in Parkinson's disease, Alzheimer's disease and related neurodegenerative diseases. Accordingly, iron chelators, antioxidants and MAO-B inhibitors have shown efficacy in a variety of cellular and animal models of CNS injury. In searching for novel antioxidant iron chelators with potential MAO-B inhibitory activity, a series of new iron chelators has been designed, synthesized and investigated. In this study, the novel chelators were further examined for their activity as antioxidants, MAO-B inhibitors and neuroprotective agents in vitro. Three of the selected chelators (M30, HLA20 and M32) were the most effective in inhibiting iron-dependent lipid peroxidation in rat brain homogenates with IC50 values (12-16 microM), which is comparable with that of desferal, a prototype iron chelator that is not has orally active. Their antioxidant activities were further confirmed using electron paramagnetic resonance spectroscopy. In PC12 cell culture, the three novel chelators at 0.1 microM were able to attenuate cell death induced by serum deprivation and by 6-hydroxydopamine. M30 possessing propargyl, the MAO inhibitory moiety of the anti-Parkinson drug rasagiline, displayed greater neuroprotective potency than that of rasagiline. In addition, in vitro, M30 was a highly potent non-selective MAO-A and MAO-B inhibitor (IC50 < 0.1 microM). However, HLA20 was more selective for MAO-B but had poor MAO inhibition, with an IC50 value of 64.2 microM. The data suggest that M30 and HLA20 might serve as leads in developing drugs with multifunctional activities for the treatment of various neurodegenerative disorders.

  2. The substrate oxidation mechanism of pyranose 2-oxidase and other related enzymes in the glucose-methanol-choline superfamily.

    Science.gov (United States)

    Wongnate, Thanyaporn; Chaiyen, Pimchai

    2013-07-01

    Enzymes in the glucose-methanol-choline (GMC) oxidoreductase superfamily catalyze the oxidation of an alcohol moiety to the corresponding aldehyde. In this review, the current understanding of the sugar oxidation mechanism in the reaction of pyranose 2-oxidase (P2O) is highlighted and compared with that of other enzymes in the GMC family for which structural and mechanistic information is available, including glucose oxidase, choline oxidase, cholesterol oxidase, cellobiose dehydrogenase, aryl-alcohol oxidase, and pyridoxine 4-oxidase. Other enzymes in the family that have been newly discovered or for which less information is available are also discussed. A large primary kinetic isotope effect was observed for the flavin reduction when 2-d-D-glucose was used as a substrate, but no solvent kinetic isotope effect was detected for the flavin reduction step. The reaction of P2O is consistent with a hydride transfer mechanism in which there is stepwise formation of d-glucose alkoxide prior to the hydride transfer. Site-directed mutagenesis of P2O and pH-dependence studies indicated that His548 is a catalytic base that facilitates the deprotonation of C2-OH in D-glucose. This finding agrees with the current mechanistic model for aryl-alcohol oxidase, glucose oxidase, cellobiose dehydrogenase, methanol oxidase, and pyridoxine 4-oxidase, but is different from that of cholesterol oxidase and choline oxidase. Although all of the GMC enzymes share similar structural folding and use the hydride transfer mechanism for flavin reduction, they appear to have subtle differences in the fine-tuned details of how they catalyze substrate oxidation. © 2013 The Authors Journal compilation © 2013 FEBS.

  3. Gene cloning and heterologous expression of pyranose 2-oxidase from the brown-rot fungus, Gloeophyllum trabeum

    Science.gov (United States)

    Diane Dietrich; Casey Crooks

    2009-01-01

    A pyranose 2-oxidase gene from the brown-rot basidiomycete Gloeophyllum trabeum was isolated using homology-based degenerate PCR. The gene structure was determined and compared to that of several pyranose 2-oxidases cloned from white-rot fungi. The G. trabeum pyranose 2-oxidase gene consists of 16 coding exons with canonical promoter CAAT and TATA elements in the 5’UTR...

  4. Cloning and Functional Analysis of the Promoter of an Ascorbate Oxidase Gene from Gossypium hirsutum.

    Directory of Open Access Journals (Sweden)

    Shan Xin

    Full Text Available Apoplastic ascorbate oxidase (AO plays significant roles in plant cell growth. However, the mechanism of underlying the transcriptional regulation of AO in Gossypium hirsutum remains unclear. Here, we obtained a 1,920-bp promoter sequence from the Gossypium hirsutum ascorbate oxidase (GhAO1 gene, and this GhAO1 promoter included a number of known cis-elements. Promoter activity analysis in overexpressing pGhAO1::GFP-GUS tobacco (Nicotiana benthamiana showed that the GhAO1 promoter exhibited high activity, driving strong reporter gene expression in tobacco trichomes, leaves and roots. Promoter 5'-deletion analysis demonstrated that truncated GhAO1 promoters with serial 5'-end deletions had different GUS activities. A 360-bp fragment was sufficient to activate GUS expression. The P-1040 region had less GUS activity than the P-720 region, suggesting that the 320-bp region from nucleotide -720 to -1040 might include a cis-element acting as a silencer. Interestingly, an auxin-responsive cis-acting element (TGA-element was uncovered in the promoter. To analyze the function of the TGA-element, tobacco leaves transformed with promoters with different 5' truncations were treated with indole-3-acetic acid (IAA. Tobacco leaves transformed with the promoter regions containing the TGA-element showed significantly increased GUS activity after IAA treatment, implying that the fragment spanning nucleotides -1760 to -1600 (which includes the TGA-element might be a key component for IAA responsiveness. Analyses of the AO promoter region and AO expression pattern in Gossypium arboreum (Ga, diploid cotton with an AA genome, Gossypium raimondii (Gr, diploid cotton with a DD genome and Gossypium hirsutum (Gh, tetraploid cotton with an AADD genome indicated that AO promoter activation and AO transcription were detected together only in D genome/sub-genome (Gr and Gh cotton. Taken together, these results suggest that the 1,920-bp GhAO1 promoter is a functional sequence

  5. Cloning and Functional Analysis of the Promoter of an Ascorbate Oxidase Gene from Gossypium hirsutum.

    Science.gov (United States)

    Xin, Shan; Tao, Chengcheng; Li, Hongbin

    2016-01-01

    Apoplastic ascorbate oxidase (AO) plays significant roles in plant cell growth. However, the mechanism of underlying the transcriptional regulation of AO in Gossypium hirsutum remains unclear. Here, we obtained a 1,920-bp promoter sequence from the Gossypium hirsutum ascorbate oxidase (GhAO1) gene, and this GhAO1 promoter included a number of known cis-elements. Promoter activity analysis in overexpressing pGhAO1::GFP-GUS tobacco (Nicotiana benthamiana) showed that the GhAO1 promoter exhibited high activity, driving strong reporter gene expression in tobacco trichomes, leaves and roots. Promoter 5'-deletion analysis demonstrated that truncated GhAO1 promoters with serial 5'-end deletions had different GUS activities. A 360-bp fragment was sufficient to activate GUS expression. The P-1040 region had less GUS activity than the P-720 region, suggesting that the 320-bp region from nucleotide -720 to -1040 might include a cis-element acting as a silencer. Interestingly, an auxin-responsive cis-acting element (TGA-element) was uncovered in the promoter. To analyze the function of the TGA-element, tobacco leaves transformed with promoters with different 5' truncations were treated with indole-3-acetic acid (IAA). Tobacco leaves transformed with the promoter regions containing the TGA-element showed significantly increased GUS activity after IAA treatment, implying that the fragment spanning nucleotides -1760 to -1600 (which includes the TGA-element) might be a key component for IAA responsiveness. Analyses of the AO promoter region and AO expression pattern in Gossypium arboreum (Ga, diploid cotton with an AA genome), Gossypium raimondii (Gr, diploid cotton with a DD genome) and Gossypium hirsutum (Gh, tetraploid cotton with an AADD genome) indicated that AO promoter activation and AO transcription were detected together only in D genome/sub-genome (Gr and Gh) cotton. Taken together, these results suggest that the 1,920-bp GhAO1 promoter is a functional sequence with a

  6. Isolation and properties of polyphenol oxidase from basidiocarps of Lactarius pergamenus Fr. (Fr. fungi

    Directory of Open Access Journals (Sweden)

    M. V. Tsivinska

    2015-04-01

    Full Text Available Fresh juice of basidiocarps of Lactarius pergamenus Fr. (Fr. fungi was subjected to ion exchange chromatography with used DEAE-toyopearl and CM-cellulose columns, as well as preparative electrophoresis in 7.5% polyacrylamide gels (pH 8.6. Three isoforms of polyphenol oxidase (PPO were discovered and two isoforms (1-1 and 1-2 were purified with a release of protein 0.42 mg/kg and 0.15 mg/kg of basidiocarps, respectively. These isoforms differ in the mobility at disc-electrophoresis in 7.5% PAGE in alkaline buffer system (pH 8.6. Specific activity of isoform 1-2 is 4.8 times higher than that of the isoforms 1-1. The molecular weight determination by gel chromatography on the Toyopearl HW-55 demonstrated that both isoforms 1-1 and 1-2 have the same 64 ± 2 kDa molecular mass. Electrophoresis in 15% PAGE in the presence of sodium dodecylsulphate and β-mercaptoethanol revealed one band with molecular mass of 64 ± 1 kDa which suggests the presence of one polypeptide chain in the molecule of the enzyme. The enzyme has demonstrated the highest activity at pH 6.0 and temperature +10 ºC, and at +70 ºC the enzyme was inactivated. The PPO activity was the highest in young mushrooms and it decreased with their age and positively correlated with the content of the milky juice. Ortho-aminophenol was most effective among all the tested substrates to determine the activity of PPO (o-, m– and p-aminophenol, catechol, tyrosine, resorcinol, phloroglucinol and its relative activity was 129% of the activity of catechol. Ascorbic acid was the most effective inhibitor of the polyphenol oxidase activity which was completely blocked at 1 mM concentration, whereas the same concentration of thiourea and sodium sulphite decreased the enzymatic activity by 40-45%. The PPO in L. pergamenus fungi basidiocarps was mainly localized in the mushroom milky juice where its high activity may be associated with protection of basidiocarps against various pathogens.

  7. Targeting NADPH oxidase decreases oxidative stress in the transgenic sickle cell mouse penis.

    Science.gov (United States)

    Musicki, Biljana; Liu, Tongyun; Sezen, Sena F; Burnett, Arthur L

    2012-08-01

    Sickle cell disease (SCD) is a state of chronic vasculopathy characterized by endothelial dysfunction and increased oxidative stress, but the sources and mechanisms responsible for reactive oxygen species (ROS) production in the penis are unknown. We evaluated whether SCD activates NADPH oxidase, induces endothelial nitric oxide synthase (eNOS) uncoupling, and decreases antioxidants in the SCD mouse penis. We further tested the hypothesis that targeting NADPH oxidase decreases oxidative stress in the SCD mouse penis. SCD transgenic (sickle) mice were used as an animal model of SCD. Hemizygous (hemi) mice served as controls. Mice received an NADPH oxidase inhibitor apocynin (10 mM in drinking water) or vehicle. Penes were excised at baseline for molecular studies. Markers of oxidative stress (4-hydroxy-2-nonenal [HNE]), sources of ROS (eNOS uncoupling and NADPH oxidase subunits p67(phox) , p47(phox) , and gp91(phox) ), and enzymatic antioxidants (superoxide dismutase [SOD]1, SOD2, catalase, and glutathione peroxidase-1 [GPx1]) were measured by Western blot in penes. Sources of ROS, oxidative stress, and enzymatic antioxidants in the SCD penis. Relative to hemi mice, SCD increased (Ppenis. Apocynin treatment of sickle mice reversed (P0.05) prevented eNOS uncoupling in the penis. Apocynin treatment of hemi mice did not affect any of these parameters. NADPH oxidase and eNOS uncoupling are sources of oxidative stress in the SCD penis; decreased GPx1 further contributes to oxidative stress. Inhibition of NADPH oxidase upregulation decreases oxidative stress, implying a major role for NADPH oxidase as a ROS source and a potential target for improving vascular function in the SCD mouse penis. © 2012 International Society for Sexual Medicine.

  8. Alternative oxidase in the branched mitochondrial respiratory network: an overview on structure, function, regulation, and role

    Directory of Open Access Journals (Sweden)

    Sluse F.E.

    1998-01-01

    Full Text Available Plants and some other organisms including protists possess a complex branched respiratory network in their mitochondria. Some pathways of this network are not energy-conserving and allow sites of energy conservation to be bypassed, leading to a decrease of the energy yield in the cells. It is a challenge to understand the regulation of the partitioning of electrons between the various energy-dissipating and -conserving pathways. This review is focused on the oxidase side of the respiratory chain that presents a cyanide-resistant energy-dissipating alternative oxidase (AOX besides the cytochrome pathway. The known structural properties of AOX are described including transmembrane topology, dimerization, and active sites. Regulation of the alternative oxidase activity is presented in detail because of its complexity. The alternative oxidase activity is dependent on substrate availability: total ubiquinone concentration and its redox state in the membrane and O2 concentration in the cell. The alternative oxidase activity can be long-term regulated (gene expression or short-term (post-translational modification, allosteric activation regulated. Electron distribution (partitioning between the alternative and cytochrome pathways during steady-state respiration is a crucial measurement to quantitatively analyze the effects of the various levels of regulation of the alternative oxidase. Three approaches are described with their specific domain of application and limitations: kinetic approach, oxygen isotope differential discrimination, and ADP/O method (thermokinetic approach. Lastly, the role of the alternative oxidase in non-thermogenic tissues is discussed in relation to the energy metabolism balance of the cell (supply in reducing equivalents/demand in energy and carbon and with harmful reactive oxygen species formation.

  9. Comparative study between dimethyl sulfoxide (dmso), allopurinol and urate oxidase administration in nephrotoxic rats induced with

    International Nuclear Information System (INIS)

    Heibashy, M.I.A.; El-Nahla, A.M.; Ibrahim, A.I.; Saleh, Sh.Y.A.

    2010-01-01

    This study was conducted to show whether DMSO, allopurinol and urate oxidase could offer ameliorating effects against abnormal alterations in kidney function tests in gentamicin (GM) induced nephrotoxic rats . Two experiments were carried out, the first one showed that daily injection of 80 mg GM/kg b. wt interapertonealy (I.P) for two weeks induced acute renal failure indicated by significant elevation in serum urea, creatinine, uric acid, potassium, inorganic phosphorus, TBARS and PTH and a significant decline in serum sodium, total and ionized calcium when compared with their corresponding values in saline injected rats. In the second experiment, comparisons were made between GM induced nephrotoxic rats and other nephrotoxic groups received daily pf I.P injection of DMSO (4 ml/kg b.wt), allopurinol (1.5 mg/100 g b.wt) and urate oxidase (10 mg/100 g b.wt) for 30 days after the incidence of nephrotoxicity. At all intervals, 10,20 and 30 days; serum urea, creatinine, uric acid, potassium, inorganic phosphorus, TBARS and PTH in DMSO, allopurinol and urate oxidase treated groups exhibited significant reduction than nephrotoxic untreated rats. During the same intervals, the levels of serum total and ionized calcium showed an opposite trend. serum sodium level did not show any significant difference between all treated groups except after 20 days , it was increased significantly in urate oxidase treated group and after 30 days in both allopurinol and urate oxidase treated groups. in term time intervals, a significant correction was recorded on the level of most measured parameters. in nephritic rats, the administration of DMSO, allopurinol or urate oxidase led to a significant amelioration effects in the kidney function tests and urate oxidase was the best protective.

  10. Shared features of S100B immunohistochemistry and cytochrome oxidase histochemistry in the ventroposterior thalamus and lateral habenula in neonatal rats.

    Science.gov (United States)

    Muneoka, Katsumasa; Funahashi, Hisayuki; Ogawa, Tetsuo; Whitaker-Azmitia, Patricia M; Shioda, Seiji

    2012-10-01

    The ventroposterior thalamus and the habenular nuclei of the epithalamus are relevant to the monoaminergic system functionally and anatomically. The glia-derived S100B protein plays a critical role in the development of the nervous system including the monoaminergic systems. In this study, we performed an immunohistochemical study of glia-related proteins including S100B, serotonin transporter, and microtubule-associated protein 2, as well as cytochrome oxidase histochemistry in neonatal rats. Results showed the same findings for S100B immunohistochemistry between the ventroposterior thalamus and the lateral habenula at postnatal day 7: intense staining in cell bodies of astrocytes, diffusely spread immunoproduct in the intercellular space, and S100B-free areas as well as a strong reaction to cytochrome oxidase histochemistry. Further common features were the scarcity of glial fibrillary acidic protein-positive astrocytes and the few apoptotic cells observed. The results of the cytochrome oxidase reaction suggested that S100B is released actively into intercellular areas in restricted brain regions showing high neuronal activity at postnatal day 7. Pathology of the ventroposterior thalamus and the habenula is suggested in mental disorders, and S100B might be a key factor for investigations in these areas. Copyright © 2012 ISDN. Published by Elsevier Ltd. All rights reserved.

  11. Development of new radiopharmaceuticals for imaging monoamine oxidase B

    International Nuclear Information System (INIS)

    Vasdev, Neil; Sadovski, Oleg; Moran, Matthew D.; Parkes, Jun; Meyer, Jeffrey H.; Houle, Sylvain; Wilson, Alan A.

    2011-01-01

    Introduction: Imaging monoamine oxidase B (MAO-B) in the central nervous system with PET is an important goal for psychiatric studies. We here report an improved and automated radiosynthesis of N-(6-[ 18 F]-fluorohexyl)-N-methylpropargylamine ([ 18 F]FHMP; [ 18 F]-1), as well as the radiosynthesis of two new promising candidates for imaging cerebral MAO-B, namely, carbon-11-labeled 3-(4-[ 11 C]-methoxyphenyl)-6-methyl-2H-1-benzopyran-2-one ([ 11 C]-2) and N-((1H-pyrrol-2-yl)methyl)-N-[ 11 C]-methyl-1-phenylmethanamine ([ 11 C]-3). Methods: Fluorine-18-labeled 1 was prepared via a tosyloxy precursor in 29%±5% uncorrected radiochemical yield, relative to [ 18 F]-fluoride. Both carbon-11-labeled compounds were prepared with [ 11 C]CH 3 I using the 'LOOP' method in 11% and 18% uncorrected radiochemical yields, respectively, relative to starting [ 11 C]CO 2 . All radiotracers had specific activities >37 GBq/μmol and were >98% radiochemically pure at end of synthesis ( 18 F]-1. While [ 11 C]-2 had moderate brain penetration and good clearance from normal brain tissue, distribution of radioactivity in brain was indicative of free and nonspecific binding. Good brain uptake was observed with [ 11 C]-3 (0.8%-1.4% injected dose per gram at 5 min postinjection), binding appeared to be reversible and distribution conformed with regional distribution of MAO-B in the rat brain. Preinjection of 3 or L-deprenyl showed a modest reduction (up to 25%) of brain activity. Conclusion: Carbon-11-labeled 3 was found to have the most favorable properties of the radiotracers evaluated; however, the signal-to-noise ratio was too low to warrant further in vivo imaging studies. Alternative radiotracers for imaging MAO-B are under development.

  12. Monamine oxidase inhibitors: current and emerging agents for Parkinson disease.

    Science.gov (United States)

    Fernandez, Hubert H; Chen, Jack J

    2007-01-01

    Monoamine oxidase type B (MAO-B) is the predominant isoform responsible for the metabolic breakdown of dopamine in the brain. Selective inhibition of brain MAO-B results in elevation of synaptosomal dopamine concentrations. Data have been reported regarding the selective MAO-B inhibitors, rasagiline and selegiline, for the symptomatic treatment of Parkinson disease (PD). Selegiline has demonstrated efficacy as monotherapy in patients with early PD (Deprenyl and Tocopherol Antioxidative Therapy of Parkinsonism study), but evidence of selegiline efficacy as adjunctive treatment in levodopa-treated PD patients with motor fluctuations is equivocal. A new formulation of selegiline (Zydis selegiline) has been evaluated in 2 small, placebo-controlled studies as adjunctive therapy to levodopa. The Zydis formulation allows pregastric absorption of selegiline, minimizing first-pass metabolism, and thereby increasing selegiline bioavailability and reducing the concentration of amphetamine metabolites. Rasagiline is a selective, second-generation, irreversible MAO-B inhibitor, with at least 5 times the potency of selegiline in vitro and in animal models. Rasagiline has demonstrated efficacy in 1 large, randomized, double-blind, placebo-controlled trial (TVP-1012 in Early Monotherapy for Parkinson's Disease Outpatients) as initial monotherapy in patients with early PD, and in 2 large, controlled trials (Parkinson's Rasagiline: Efficacy and Safety in the Treatment of "Off," Lasting Effect in Adjunct Therapy With Rasagiline Given Once Daily) as adjunctive treatment in levodopa-treated PD patients with motor fluctuations. Unlike selegiline, rasagiline is an aminoindan derivative with no amphetamine metabolites. A randomized clinical trial is underway to confirm preclinical and preliminary clinical data suggesting rasagiline has disease-modifying effects.

  13. NADPH Oxidase, NOX1, Mediates Vascular Injury in Ischemic Retinopathy

    Science.gov (United States)

    Deliyanti, Devy; Rana, Indrajeetsinh; Miller, Antonia G.; Agrotis, Alex; Armani, Roksana; Szyndralewiez, Cédric; Wingler, Kirstin; Touyz, Rhian M.; Cooper, Mark E.; Jandeleit-Dahm, Karin A.; Schmidt, Harald H.H.W.

    2014-01-01

    Abstract Aims: Ischemic retinal diseases such as retinopathy of prematurity are major causes of blindness due to damage to the retinal microvasculature. Despite this clinical situation, retinopathy of prematurity is mechanistically poorly understood. Therefore, effective preventative therapies are not available. However, hypoxic-induced increases in reactive oxygen species (ROS) have been suggested to be involved with NADPH oxidases (NOX), the only known dedicated enzymatic source of ROS. Our major aim was to determine the contribution of NOX isoforms (1, 2, and 4) to a rodent model of retinopathy of prematurity. Results: Using a genetic approach, we determined that only mice with a deletion of NOX1, but not NOX2 or NOX4, were protected from retinal neovascularization and vaso-obliteration, adhesion of leukocytes, microglial accumulation, and the increased generation of proangiogenic and proinflammatory factors and ROS. We complemented these studies by showing that the specific NOX inhibitor, GKT137831, reduced vasculopathy and ROS levels in retina. The source of NOX isoforms was evaluated in retinal vascular cells and neuro-glial elements. Microglia, the immune cells of the retina, expressed NOX1, 2, and 4 and responded to hypoxia with increased ROS formation, which was reduced by GKT137831. Innovation: Our studies are the first to identify the NOX1 isoform as having an important role in the pathogenesis of retinopathy of prematurity. Conclusions: Our findings suggest that strategies targeting NOX1 have the potential to be effective treatments for a range of ischemic retinopathies. Antioxid. Redox Signal. 20, 2726–2740. PMID:24053718

  14. Novel thidiazuron-derived inhibitors of cytokinin oxidase/dehydrogenase.

    Science.gov (United States)

    Nisler, Jaroslav; Kopečný, David; Končitíková, Radka; Zatloukal, Marek; Bazgier, Václav; Berka, Karel; Zalabák, David; Briozzo, Pierre; Strnad, Miroslav; Spíchal, Lukáš

    2016-09-01

    Two new TDZ derivatives (HETDZ and 3FMTDZ) are very potent inhibitors of CKX and are promising candidates for in vivo studies. Cytokinin hormones regulate a wide range of essential processes in plants. Thidiazuron (N-phenyl-N'-1,2,3-thiadiazol-5-yl urea, TDZ), formerly registered as a cotton defoliant, is a well known inhibitor of cytokinin oxidase/dehydrogenase (CKX), an enzyme catalyzing the degradation of cytokinins. TDZ thus increases the lifetime of cytokinins and their effects in plants. We used in silico modeling to design, synthesize and characterize twenty new TDZ derivatives with improved inhibitory properties. Two compounds, namely 1-[1,2,3]thiadiazol-5-yl-3-(3-trifluoromethoxy-phenyl)urea (3FMTDZ) and 1-[2-(2-hydroxyethyl)phenyl]-3-(1,2,3-thiadiazol-5-yl)urea (HETDZ), displayed up to 15-fold lower IC 50 values compared with TDZ for AtCKX2 from Arabidopsis thaliana and ZmCKX1 and ZmCKX4a from Zea mays. Binding modes of 3FMTDZ and HETDZ were analyzed by X-ray crystallography. Crystal structure complexes, solved at 2.0 Å resolution, revealed that HETDZ and 3FMTDZ bound differently in the active site of ZmCKX4a: the thiadiazolyl ring of 3FMTDZ was positioned over the isoalloxazine ring of FAD, whereas that of HETDZ had the opposite orientation, pointing toward the entrance of the active site. The compounds were further tested for cytokinin activity in several cytokinin bioassays. We suggest that the combination of simple synthesis, lowered cytokinin activity, and enhanced inhibitory effects on CKX isoforms, makes 3FMTDZ and HETDZ suitable candidates for in vivo studies.

  15. Alterations of sirtuins in mitochondrial cytochrome c-oxidase deficiency.

    Directory of Open Access Journals (Sweden)

    Arne Björn Potthast

    Full Text Available Sirtuins are NAD+ dependent deacetylases, which regulate mitochondrial energy metabolism as well as cellular response to stress. The NAD/NADH-system plays a crucial role in oxidative phosphorylation linking sirtuins and the mitochondrial respiratory chain. Furthermore, sirtuins are able to directly deacetylate and activate different complexes of the respiratory chain. This prompted us to analyse sirtuin levels in skin fibroblasts from patients with cytochrome c-oxidase (COX deficiency and to test the impact of different pharmaceutical activators of sirtuins (SRT1720, paeonol to modulate sirtuins and possibly respiratory chain enzymes in patient cells in vitro.We assayed intracellular levels of sirtuin 1 and the mitochondrial sirtuins SIRT3 and SIRT4 in human fibroblasts from patients with COX- deficiency. Furthermore, sirtuins were measured after inhibiting complex IV in healthy control fibroblasts by cyanide and after incubation with activators SRT1720 and paeonol. To determine the effect of sirtuin inhibition at the cellular level we measured total cellular acetylation (control and patient cells, with and without treatment by Western blot.We observed a significant decrease in cellular levels of all three sirtuins at the activity, protein and transcriptional level (by 15% to 50% in COX-deficient cells. Additionally, the intracellular concentration of NAD+ was reduced in patient cells. We mimicked the biochemical phenotype of COX- deficiency by incubating healthy fibroblasts with cyanide and observed reduced sirtuin levels. A pharmacological activation of sirtuins resulted in normalized sirtuin levels in patient cells. Hyper acetylation was also reversible after treatment with sirtuin activators. Pharmacological modulation of sirtuins resulted in altered respiratory chain complex activities.We found inhibition of situins 1, 3 and 4 at activity, protein and transcriptional levels in fibroblasts from patient with COX-deficiency. Pharmacological

  16. Insomnia, platelet serotonin and platelet monoamine oxidase in chronic alcoholism.

    Science.gov (United States)

    Nenadic Sviglin, Korona; Nedic, Gordana; Nikolac, Matea; Mustapic, Maja; Muck-Seler, Dorotea; Borovecki, Fran; Pivac, Nela

    2011-08-18

    Insomnia is a common sleep disorder frequently occurring in chronic alcoholic patients. Neurobiological basis of insomnia, as well as of alcoholism, is associated with disrupted functions of the main neurotransmitter systems, including the serotonin (5-hydroxytryptamine, 5-HT) system. Blood platelets are considered a limited peripheral model for the central 5-HT neurons, since both platelets and central 5-HT synaptosomes have similar dynamics of 5-HT. Platelet 5-HT concentration and platelet monoamine oxidase type B (MAO-B) are assumed to represent biomarkers for particular symptoms and behaviors in psychiatric disorders. The hypothesis of this study was that platelet 5-HT concentration and platelet MAO-B activity will be altered in chronic alcoholic patients with insomnia compared to comparable values in patients without insomnia. The study included 498 subjects: 395 male and 103 female medication-free patients with alcohol dependence and 502 healthy control subjects: 325 men and 177 women. The effects of early, middle and late insomnia (evaluated using the Hamilton Depression Rating Scale), as well as sex, age and smoking on platelet 5-HT concentration and platelet MAO-B activity were evaluated using one-way ANOVA and multiple regression analysis by the stepwise method. Platelet 5-HT concentration, but not platelet MAO-B activity, was significantly reduced in alcoholic patients with insomnia compared to patients without insomnia. Multiple regression analysis revealed that platelet 5-HT concentration was affected by middle insomnia, smoking and sex, while platelet MAO activity was affected only by sex and age. The present and previous data suggest that platelet 5-HT concentration might be used, after controlling for sex and smoking, as a biomarker for insomnia in alcoholism, PTSD and in rotating shift workers. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  17. Layer by layer assembly of glucose oxidase and thiourea onto glassy carbon electrode: Fabrication of glucose biosensor

    International Nuclear Information System (INIS)

    Salimi, Abdollah; Noorbakhsh, Abdollah

    2011-01-01

    Highlights: → Although various enzymes immobilization have been approve for the construction of glucose biosensor, a layer by layer (LBL) technique has attracted more attention due to simplicity of the procedure, wide choice of materials that can be used, controllability of film thickness and unique mechanical properties. → In this paper, we described a novel and simple strategy for developing an amperometric glucose biosensor based on layer-by-layer self assembly of glucose oxidase on the glassy carbon electrode modified by thiourea. → Thiourea has two amino groups that the one can be immobilized on the activated glassy carbon electrode and the other can be used for the coupling of glucose oxidase enzyme. → The biosensor exhibited good performance for electrocatalytic oxidation of glucose, such as high sensitivity, low detection limit, short response time and wide concentration range. → Finally, the new method is strongly recommended for immobilization of many other enzymes or proteins containing carbaldehyde or carboxylic groups for fabricating third generation biosensors and bioelectronics devices. - Abstract: For the first time a novel, simple and facile approach is described to construct highly stable glucose oxidase (GOx) multilayer onto glassy carbon (GC) electrode using thiourea (TU) as a covalent attachment cross-linker. The layer by layer (LBL) attachment process was confirmed by cyclic voltammetry, electrochemical impedance spectroscopy and Fourier transform infrared reflection spectroscopy (FT-IR-RS) techniques. Immobilized GOx shows excellent electrocatalytic activity toward glucose oxidation using ferrocenemethanol as artificial electron transfer mediator and biosensor response was directly correlated to the number of bilayers. The surface coverage of active GOx per bilayer, heterogeneous electron transfer rate constant (k s ) and Michaelis-Menten constant (K M ), of immobilized GOx were 1.50 x 10 -12 mol cm -2 , 9.2 ± 0.5 s -1 and 3.42(±0

  18. Layer by layer assembly of glucose oxidase and thiourea onto glassy carbon electrode: Fabrication of glucose biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Salimi, Abdollah, E-mail: absalimi@yahoo.com [Department of Chemistry, University of Kurdistsn, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Noorbakhsh, Abdollah [Department of Chemistry, University of Kurdistsn, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Department of Nanotechnology Engenering, Faculty of Advanced Science and Technology, University of Isfahan, 81746-73441 (Iran, Islamic Republic of)

    2011-07-01

    Highlights: > Although various enzymes immobilization have been approve for the construction of glucose biosensor, a layer by layer (LBL) technique has attracted more attention due to simplicity of the procedure, wide choice of materials that can be used, controllability of film thickness and unique mechanical properties. > In this paper, we described a novel and simple strategy for developing an amperometric glucose biosensor based on layer-by-layer self assembly of glucose oxidase on the glassy carbon electrode modified by thiourea. > Thiourea has two amino groups that the one can be immobilized on the activated glassy carbon electrode and the other can be used for the coupling of glucose oxidase enzyme. > The biosensor exhibited good performance for electrocatalytic oxidation of glucose, such as high sensitivity, low detection limit, short response time and wide concentration range. > Finally, the new method is strongly recommended for immobilization of many other enzymes or proteins containing carbaldehyde or carboxylic groups for fabricating third generation biosensors and bioelectronics devices. - Abstract: For the first time a novel, simple and facile approach is described to construct highly stable glucose oxidase (GOx) multilayer onto glassy carbon (GC) electrode using thiourea (TU) as a covalent attachment cross-linker. The layer by layer (LBL) attachment process was confirmed by cyclic voltammetry, electrochemical impedance spectroscopy and Fourier transform infrared reflection spectroscopy (FT-IR-RS) techniques. Immobilized GOx shows excellent electrocatalytic activity toward glucose oxidation using ferrocenemethanol as artificial electron transfer mediator and biosensor response was directly correlated to the number of bilayers. The surface coverage of active GOx per bilayer, heterogeneous electron transfer rate constant (k{sub s}) and Michaelis-Menten constant (K{sub M}), of immobilized GOx were 1.50 x 10{sup -12} mol cm{sup -2}, 9.2 {+-} 0.5 s{sup -1

  19. New biotechnological perspectives of a NADH oxidase variant from Thermus thermophilus HB27 as NAD+-recycling enzyme

    Directory of Open Access Journals (Sweden)

    Rocha-Martín Javier

    2011-11-01

    Full Text Available Abstract Background The number of biotransformations that use nicotinamide recycling systems is exponentially growing. For this reason one of the current challenges in biocatalysis is to develop and optimize more simple and efficient cofactor recycling systems. One promising approach to regenerate NAD+ pools is the use of NADH-oxidases that reduce oxygen to hydrogen peroxide while oxidizing NADH to NAD+. This class of enzymes may be applied to asymmetric reduction of prochiral substrates in order to obtain enantiopure compounds. Results The NADH-oxidase (NOX presented here is a flavoenzyme which needs exogenous FAD or FMN to reach its maximum velocity. Interestingly, this enzyme is 6-fold hyperactivated by incubation at high temperatures (80°C under limiting concentrations of flavin cofactor, a change that remains stable even at low temperatures (37°C. The hyperactivated form presented a high specific activity (37.5 U/mg at low temperatures despite isolation from a thermophile source. Immobilization of NOX onto agarose activated with glyoxyl groups yielded the most stable enzyme preparation (6-fold more stable than the hyperactivated soluble enzyme. The immobilized derivative was able to be reactivated under physiological conditions after inactivation by high solvent concentrations. The inactivation/reactivation cycle could be repeated at least three times, recovering full NOX activity in all cases after the reactivation step. This immobilized catalyst is presented as a recycling partner for a thermophile alcohol dehydrogenase in order to perform the kinetic resolution secondary alcohols. Conclusion We have designed, developed and characterized a heterogeneous and robust biocatalyst which has been used as recycling partner in the kinetic resolution of rac-1-phenylethanol. The high stability along with its capability to be reactivated makes this biocatalyst highly re-useable for cofactor recycling in redox biotransformations.

  20. High Catalysis Activity of Cu2O Microcrystals to the Electrochemiluminesence of Luminol and H2O2

    DEFF Research Database (Denmark)

    Zhang, Ling; Xu, Guobao; Zhang, Jingdong

    Cuprous oxide (Cu2O) is a classical p-type semiconductor with a direct band gap of 2.17 eV, which is wildly used for solar energy conversion, CO oxidation, and photo catalytic water splitting for the low cost and environmental friendliness. For the energy band positions are favorable to the hydro......Cuprous oxide (Cu2O) is a classical p-type semiconductor with a direct band gap of 2.17 eV, which is wildly used for solar energy conversion, CO oxidation, and photo catalytic water splitting for the low cost and environmental friendliness. For the energy band positions are favorable...... to the hydrogen evolution and oxygen evolution potentials, Cu2O materials also catalyze the reduction of hydrogen peroxide (H2O2), which is an critical molecule in the bodies’ metabolism processes or the industrial catalysis reactions. To improve detection sensitivity of H2O2, people have composed Cu2O materials...... that Cu2O semiconductor microcrystal possess the good catalytic performance to this ECL reaction, which is important to develop the high-efficient and lowcost biosensors....

  1. Determination of the rate constant for neuronal and extra-neuronal monoamine oxidase

    International Nuclear Information System (INIS)

    Cassis, L.; Ludwig, J.; Trendelenburg, U.

    1986-01-01

    In the rat vas deferens, neuronal deamination of 3 H-(-) noradrenaline ( 3 H-NA) to 3 H-dihydroxyphenethylglycol ( 3 HDOPEG) cannot be inhibited by pretreatment with a monoamine oxidase (MAO) inhibitor. However, in the extraneuronal compartment of the rat heart, inhibition of MAO abolishes the formation of 3 HDOPEG. To clarify this discrepancy, the authors determined the rate constant for MAO (/sup k/mao/) neuronally (rat vas deferens) and extraneuronally (rat heart). For neuronal /sup k/mao, vasa deferentia were incubated with 3 HNA for 300 minutes, and the cumulative formation of 3 HDOPEG measured. The delay in time before 3 HDOPEG achieves steady state (/sup tau/system), is inversely proportional to /sup k/mao. Because /sup tau/system is very short for neuronal MAO, an appreciable delay was only achieved after partial inhibition of MAO with various parglyline concentrations. To relate to the uninhibited enzyme, the percentage inhibition by pargyline was then determined in homogenate preparations. For extraneuronal MAO, a similar procedure was performed in perfused rat hearts. Results show a significantly greater /sup k/mao of neuronal origin, (/sup k/mao = .57min - 1) which when related to the fractional size of the neuronal compartment suggests a very high activity of neuronal MAO

  2. Direct electrochemistry of glucose oxidase assembled on graphene and application to glucose detection

    International Nuclear Information System (INIS)

    Wu Ping; Shao Qian; Hu Yaojuan; Jin Juan; Yin Yajing; Zhang Hui; Cai Chenxin

    2010-01-01

    The direct electrochemistry of glucose oxidase (GOx) integrated with graphene was investigated. The voltammetric results indicated that GOx assembled on graphene retained its native structure and bioactivity, exhibited a surface-confined process, and underwent effective direct electron transfer (DET) reaction with an apparent rate constant (k s ) of 2.68 s -1 . This work also developed a novel approach for glucose detection based on the electrocatalytic reduction of oxygen at the GOx-graphene/GC electrode. The assembled GOx could electrocatalyze the reduction of dissolved oxygen. Upon the addition of glucose, the reduction current decreased, which could be used for glucose detection with a high sensitivity (ca. 110 ± 3 μA mM -1 cm -2 ), a wide linear range (0.1-10 mM), and a low detection limit (10 ± 2 μM). The developed approach can efficiently exclude the interference of commonly coexisting electroactive species due to the use of a low detection potential (-470 mV, versus SCE). Therefore, this study has not only successfully achieved DET reaction of GOx assembled on graphene, but also established a novel approach for glucose detection and provided a general route for fabricating graphene-based biosensing platform via assembling enzymes/proteins on graphene surface.

  3. Glucose biosensor based on glucose oxidase immobilized on unhybridized titanium dioxide nanotube arrays

    International Nuclear Information System (INIS)

    Wang, Wei; Xie, Yibing; Du, Hongxiu; Xia, Chi; Wang, Yong; Tian, Fang

    2014-01-01

    A glucose biosensor has been fabricated by immobilizing glucose oxidase (GOx) on unhybridized titanium dioxide nanotube arrays using an optimized cross-linking technique. The TiO 2 nanotube arrays were synthesized directly on a titanium substrate by anodic oxidation. The structure and morphology of electrode material were characterized by X-ray diffraction and scanning electron microscopy. The electrochemical performances of the glucose biosensor were conducted by cyclic voltammetry and chronoamperometry measurements. It gives a linear response to glucose in the 0.05 to 0.65 mM concentration range, with a correlation coefficient of 0.9981, a sensitivity of 199.6 μA mM −1 cm −2 , and a detection limit as low as 3.8 µM. This glucose biosensor exhibited high selectivity for glucose determination in the presence of ascorbic acid, sucrose and other common interfering substances. This glucose biosensor also performed good reproducibility and long-time storage stability. This optimized cross-linking technique could open a new avenue for other enzyme biosensors fabrication. (author)

  4. Direct electrochemistry of glucose oxidase and glucose biosensing on a hydroxyl fullerenes modified glassy carbon electrode.

    Science.gov (United States)

    Gao, Yun-Fei; Yang, Tian; Yang, Xiao-Lu; Zhang, Yu-Shuai; Xiao, Bao-Lin; Hong, Jun; Sheibani, Nader; Ghourchian, Hedayatollah; Hong, Tao; Moosavi-Movahedi, Ali Akbar

    2014-10-15

    Direct electrochemistry of glucose oxidase (GOD) was achieved when GOD-hydroxyl fullerenes (HFs) nano-complex was immobilized on a glassy carbon (GC) electrode and protected with a chitosan (Chit) membrane. The ultraviolet-visible absorption spectrometry (UV-vis), transmission electron microscopy (TEM), and circular dichroism spectropolarimeter (CD) methods were utilized for additional characterization of the GOD, GOD-HFs and Chit/GOD-HFs. Chit/HFs may preserve the secondary structure and catalytic properties of GOD. The cyclic voltammograms (CVs) of the modified GC electrode showed a pair of well-defined quasi-reversible redox peaks with the formal potential (E°') of 353 ± 2 mV versus Ag/AgCl at a scan rate of 0.05 V/s. The heterogeneous electron transfer constant (ks) was calculated to be 2.7 ± 0.2s(-1). The modified electrode response to glucose was linear in the concentrations ranging from 0.05 to 1.0mM, with a detection limit of 5 ± 1 μM. The apparent Michaelis-Menten constant (Km(app)) was 694 ± 8 μM. Thus, the modified electrode could be applied as a third generation biosensor for glucose with high sensitivity, selectivity and low detection limit. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Glucose oxidase-graphene-chitosan modified electrode for direct electrochemistry and glucose sensing

    International Nuclear Information System (INIS)

    Kang, Xinhuang; Wang, Jun; Wu, Hong; Aksay, Ilhan A.; Liu, Jun; Lin, Yuehe

    2009-01-01

    Direct electrochemistry of a glucose oxidase (GOD)/graphene/chitosan nanocomposite was studied. The immobilized enzyme retains its bioactivity, exhibits a surface confined, reversible two-proton and two-electron transfer reaction, and has good stability, activity and a fast heterogeneous electron transfer rate with the rate constant (k s ) of 2.83 s -1 . A much higher enzyme loading (1.12 x 10 -9 mol/cm 2 ) is obtained as compared to the bare glass carbon surface. This GOD/graphene/chitosan nanocomposite film can be used for sensitive detection of glucose. The biosensor exhibits a wider linearity range from 0.08 mM to 12 mM glucose with a detection limit of 0.02 mM and much higher sensitivity (37.93 (micro)A mM -1 cm -2 ) as compared with other nanostructured supports. The excellent performance of the biosensor is attributed to large surface-to-volume ratio and high conductivity of graphene, and good biocompatibility of chitosan, which enhances the enzyme absorption and promotes direct electron transfer between redox enzymes and the surface of electrodes.

  6. Graphene oxide-mediated electrochemistry of glucose oxidase on glassy carbon electrodes.

    Science.gov (United States)

    Castrignanò, Silvia; Valetti, Francesca; Gilardi, Gianfranco; Sadeghi, Sheila J

    2016-01-01

    Glucose oxidase (GOD) was immobilized on glassy carbon electrodes in the presence of graphene oxide (GO) as a model system for the interaction between GO and biological molecules. Lyotropic properties of didodecyldimethylammonium bromide (DDAB) were used to stabilize the enzymatic layer on the electrode surface resulting in a markedly improved electrochemical response of the immobilized GOD. Transmission electron microscopy images of the GO with DDAB confirmed the distribution of the GO in a two-dimensional manner as a foil-like material. Although it is known that glassy carbon surfaces are not ideal for hydrogen peroxide detection, successful chronoamperometric titrations of the GOD in the presence of GO with β-d-glucose were performed on glassy carbon electrodes, whereas no current response was detected upon β-d-glucose addition in the absence of GO. The GOD-DDAB-GO system displayed a high turnover efficiency and substrate affinity as a glucose biosensor. The simplicity and ease of the electrode preparation procedure of this GO/DDAB system make it a good candidate for immobilizing other biomolecules for fabrication of amperometric biosensors. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

  7. Glucose oxidase immobilization on different modified surfaces of platinum nanowire for application in glucose detection

    International Nuclear Information System (INIS)

    Le, Thi Thanh Tuyen; Tran, Phu Duy; Pham, Xuan Tung; Tong, Duy Hien; Dang, Mau Chien

    2010-01-01

    In this work, the surface of platinum (Pt) nanowires was modified by using several chemicals, including a compound of gelatin gel with SiO 2 , polyvinyl alcohol (PVA) with Prussian blue (PB) mediator and cysteamine self-assembled monolayers (SAM). Then, glucose oxidase (GOD) enzyme was immobilized on the modified surfaces of Pt nanowire electrodes by using techniques of electrochemical adsorption and chemical binding. The GOD immobilized Pt nanowires were used for application in glucose detection by performing a cyclic voltammetry measurement. The detection results showed that GOD was immobilized on all of the tested surfaces and the highest glucose detection sensitivity of 60 μM was obtained when the Pt nanowires were modified by PVA with PB mediator. Moreover, the sensors showed very high current response when the Pt nanowires were modified with the cysteamine SAM. The stability and catalyst activity of GOD are also reported here. For instance, the catalyst activity of GOD retained about 60% of its initial value after it was stored at 4 °C in a 100 mM PBS buffer solution with a pH of 7.2 for a period of 30 days

  8. Zinc oxide inverse opal electrodes modified by glucose oxidase for electrochemical and photoelectrochemical biosensor.

    Science.gov (United States)

    Xia, Lei; Song, Jian; Xu, Ru; Liu, Dali; Dong, Biao; Xu, Lin; Song, Hongwei

    2014-09-15

    The ZnO inverse opal photonic crystals (IOPCs) were synthesized by the sol-gel method using the polymethylmethacrylate (PMMA) as a template. For glucose detection, glucose oxidase (GOD) was further immobilized on the inwall and surface of the IOPCs. The biosensing properties toward glucose of the Nafion/GOD/ZnO IOPCs modified FTO electrodes were carefully studied and the results indicated that the sensitivity of ZnO IOPCs modified electrode was 18 times than reference electrode due to the large surface area and uniform porous structure of ZnO IOPCs. Moreover, photoelectrochemical detection for glucose using the electrode was realized and the sensitivity approached to 52.4 µA mM(-1) cm(-2), which was about four times to electrochemical detection (14.1 µA mM(-1) cm(-2)). It indicated that photoelectrochemical detection can highly improve the sensor performance than conventional electrochemical method. It also exhibited an excellent anti-interference property and a good stability at the same time. This work provides a promising approach for realizing excellent photoelectrochemical biosensor of similar semiconductor photoelectric material. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Effect of phenol on germination capacity and polyphenol oxidase, peroxidase and catalase activities in lettuce

    Directory of Open Access Journals (Sweden)

    Tadić Vojin

    2014-01-01

    Full Text Available In this study we examined the activities of polyphenol oxidase (PPO and antioxidant enzymes, peroxidase (POX and catalase (CAT during lettuce seed germination at different concentrations of phenol. Out of eleven varieties of lettuce, four were chosen according to their germination tolerance to phenol as follows: plants exhibiting high (Ljubljanska ledenka - LJL and Nansen - N and low toleranace (Little Gem - LG and Majska kraljica - MK. A decrease in germination efficiency after exposure to LD50 of phenol was determined for these four varieties. The effects of phenol treatment on POX, CAT and PPO activities were determined after 4, 5, 6, 7 and 8 days of growth at LD50 concentrations. A trend of increased peroxidase activity was observed in seeds grown on LD50 of phenol compared to control seeds. A significant increase in CAT activity was observed at the beginning of treatment for MK, LG and N in seeds grown on phenol as well as in control seeds. A trend of increased PPO activity was observed in all control seeds. We also investigated the affinity of PPO for two different substrates that were used for the determination of enzyme activity. Our results show that LJL and N are the varieties most tolerant to growth on phenol. Here we report on the activities of their antioxidant enzymes and PPO during seed germination. [Projekat Ministarstva nauke Republike Srbije, br. ON173017

  10. Preparation of cholesterol oxidase nanoparticles and their application in amperometric determination of cholesterol

    Energy Technology Data Exchange (ETDEWEB)

    Chawla, Sheetal; Rawal, Rachna; Sonia; Ramrati; Pundir, C. S., E-mail: pundircs@rediffmail.com [M. D. University, Department of Biochemistry (India)

    2013-09-15

    The nanoparticle (NP) aggregates of commercial cholesterol oxidase (ChOx) were prepared by desolvation method. The formation and characterization of ChOxNP aggregates were studied by transmission electron microscopy and scanning electron microscopy. NP aggregates were more stable, active and had a higher shelf life than that of free enzyme. An amperometric cholesterol biosensor was constructed by immobilizing ChOxNPs onto Au electrode. The biosensor showed optimum response within 8 s at pH 6.0 and 35 Degree-Sign C, when polarized at +0.27 V versus Ag/AgCl. The biosensor possesses high sensitivity and measures cholesterol concentrations as low as 1.56 mg/dl. The working linear range was 12.5-700 mg/dl for cholesterol. The biosensor was evaluated and employed for measurement of total cholesterol in human serum. The enzyme electrode lost 50 % of its initial activity during its regular use for 180 times over a period of 90 days when stored in 0.1 M sodium phosphate buffer, pH 7.0 at 4 Degree-Sign C.

  11. Glucose Sensor Using U-Shaped Optical Fiber Probe with Gold Nanoparticles and Glucose Oxidase.

    Science.gov (United States)

    Chen, Kuan-Chieh; Li, Yu-Le; Wu, Chao-Wei; Chiang, Chia-Chin

    2018-04-16

    In this study, we proposed a U-shaped optical fiber probe fabricated using a flame heating method. The probe was packaged in glass tube to reduce human factors during experimental testing of the probe as a glucose sensor. The U-shaped fiber probe was found to have high sensitivity in detecting the very small molecule. When the sensor was dipped in solutions with different refractive indexes, its wavelength or transmission loss changed. We used electrostatic self-assembly to bond gold nanoparticles and glucose oxidase (GOD) onto the sensor’s surface. The results over five cycles of the experiment showed that, as the glucose concentration increased, the refractive index of the sensor decreased and its spectrum wavelength shifted. The best wavelength sensitivity was 2.899 nm/%, and the linearity was 0.9771. The best transmission loss sensitivity was 5.101 dB/%, and the linearity was 0.9734. Therefore, the proposed U-shaped optical fiber probe with gold nanoparticles and GOD has good potential for use as a blood sugar sensor in the future.

  12. Monoamine Oxidase-A Inhibition and Associated Antioxidant Activity in Plant Extracts with Potential Antidepressant Actions

    Directory of Open Access Journals (Sweden)

    Tomás Herraiz

    2018-01-01

    Full Text Available Monoamine oxidase (MAO catalyzes the oxidative deamination of amines and neurotransmitters and is involved in mood disorders, depression, oxidative stress, and adverse pharmacological reactions. This work studies the inhibition of human MAO-A by Hypericum perforatum, Peganum harmala, and Lepidium meyenii, which are reported to improve and affect mood and mental conditions. Subsequently, the antioxidant activity associated with the inhibition of MAO is determined in plant extracts for the first time. H. perforatum inhibited human MAO-A, and extracts from flowers gave the highest inhibition (IC50 of 63.6 μg/mL. Plant extracts were analyzed by HPLC-DAD-MS and contained pseudohypericin, hypericin, hyperforin, adhyperforin, hyperfirin, and flavonoids. Hyperforin did not inhibit human MAO-A and hypericin was a poor inhibitor of this isoenzyme. Quercetin and flavonoids significantly contributed to MAO-A inhibition. P. harmala seed extracts highly inhibited MAO-A (IC50 of 49.9 μg/L, being a thousand times more potent than H. perforatum extracts owing to its content of β-carboline alkaloids (harmaline and harmine. L. meyenii root (maca extracts did not inhibit MAO-A. These plants may exert protective actions related to antioxidant effects. Results in this work show that P. harmala and H. perforatum extracts exhibit antioxidant activity associated with the inhibition of MAO (i.e., lower production of H2O2.

  13. Monoamine Oxidase A in Antisocial Personality Disorder and Borderline Personality Disorder.

    Science.gov (United States)

    Kolla, Nathan J; Vinette, Sarah A

    2017-01-01

    Variation in the monoamine oxidase A (MAO-A) gene and MAO-A enzyme levels have been linked to antisocial behavior and aggression in clinical and non-clinical populations. Here, we provide an overview of the genetic, epigenetic, and neuroimaging research that has examined MAO-A structure and function in antisocial personality disorder (ASPD) and borderline personality disorder (BPD). The low-activity MAO-A variable nucleotide tandem repeat genetic polymorphism has shown a robust association with large samples of violent and seriously violent offenders, many of whom had ASPD. A recent positron emission tomography (PET) study of ASPD similarly revealed low MAO-A density in brain regions thought to contribute to the psychopathology of the condition. By contrast, PET has also demonstrated that brain MAO-A levels are increased in BPD and that they relate to symptoms of low mood and suicidality. Candidate gene studies have produced the most compelling evidence connecting MAO-A genetic variants to both ASPD and BPD. Still, conflicting results abound in the literature, making it highly unlikely that ASPD or BPD is related to a specific MAO-A genetic variant. Future research should strive to examine how MAO-A genotypes interact with broad-spectrum environmental influences to produce brain endophenotypes that may ultimately become tractable targets for novel treatment strategies.

  14. Hydrazine and hydroxylamine as probes for O2-reduction site of mitochondrial cytochrome c oxidase.

    Science.gov (United States)

    Kubota, T; Yoshikawa, S

    1993-01-01

    Reactions of hydrazine and hydroxylamine with bovine heart cytochrome c oxidase in the fully reduced state were investigated under anaerobic conditions following the visible-Soret spectral change. Hydrazine gave a sharp band at 575 nm with 20% decrease in the alpha band at 603 nm, and hydroxylamine induced a 2 nm blue-shift for the alpha band without any clear splitting. The Soret band at 443 nm was decreased significantly in intensity, with the concomitant appearance of a shoulder with hydrazine or a peak with hydroxylamine, both near 430 nm. The dependence on pH of the affinity of these reagents for the enzyme indicates that only the deprotonated forms of these reagents bind to the enzyme, suggesting a highly hydrophobic environment of the haem ligand-biding site. These spectral changes were largely removed by addition of cyanide or CO. However, detailed analysis of these spectral changes indicates that hydrazine perturbs the shape of the spectral change induced by cyanide and hydroxylamine perturbs that induced by CO. These results suggest that these aldehyde reagents bind to haem a3 iron as well as to a second site which is most likely to be the formyl group on the haem periphery, and that these two sites bind these reagents anti-cooperatively with each other. PMID:8389138

  15. Interaction of a snake venom L-amino acid oxidase with different cell types membrane.

    Science.gov (United States)

    Abdelkafi-Koubaa, Zaineb; Aissa, Imen; Morjen, Maram; Kharrat, Nadia; El Ayeb, Mohamed; Gargouri, Youssef; Srairi-Abid, Najet; Marrakchi, Naziha

    2016-01-01

    Snake venom l-amino acid oxidases are multifunctional enzymes that exhibited a wide range of pharmacological activities. Although it has been established that these activities are primarily caused by the H2O2 generated in the enzymatic reaction, the molecular mechanism, however, has not been fully investigated. In this work, LAAO interaction with cytoplasmic membranes using different cell types and Langmuir interfacial monolayers was evaluated. The Cerastes cerastes venom LAAO (CC-LAAO) did not exhibit cytotoxic activities against erythrocytes and peripheral blood mononuclear cells (PBMC). However, CC-LAAO caused cytotoxicity on several cancer cell lines and induced platelet aggregation in dose-dependent manner. Furthermore, the enzyme showed remarkable effect against Gram-positive and Gram-negative bacteria. These activities were inhibited on the addition of catalase or substrate analogs, suggesting that H2O2 liberation× is required for these effects. Binding studies revealed that CC-LAAO binds to the cell surface and enables the production of highly localized concentration of H2O2 in or near the binding interfaces. On another hand, the interaction of CC-LAAO with a mimetic phospholipid film was evaluated, for the first time, using a monomolecular film technique. Results indicated that phospholipid/CC-LAAO interactions are not involved in their binding to membrane and in their pharmacological activities. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Metabonomics revealed xanthine oxidase-induced oxidative stress and inflammation in the pathogenesis of diabetic nephropathy.

    Science.gov (United States)

    Liu, Jingping; Wang, Chengshi; Liu, Fang; Lu, Yanrong; Cheng, Jingqiu

    2015-03-01

    Diabetic nephropathy (DN) is a serious complication of diabetes mellitus (DM), which is a major public health problem in the world. To reveal the metabolic changes associated with DN, we analyzed the serum, urine, and renal extracts obtained from control and streptozotocin (STZ)-induced DN rats by (1)H NMR-based metabonomics and multivariate data analysis. A significant difference between control and DN rats was revealed in metabolic profiles, and we identified several important DN-related metabolites including increased levels of allantoin and uric acid (UA) in the DN rats, suggesting that disturbed purine metabolism may be involved in the DN. Combined with conventional histological and biological methods, we further demonstrated that xanthine oxidase (XO), a key enzyme for purine catabolism, was abnormally activated in the kidney of diabetic rats by hyperglycemia. The highly activated XO increased the level of intracellular ROS, which caused renal injury by direct oxidative damage to renal cells, and indirect inducing inflammatory responses via activating NF-κB signaling pathway. Our study highlighted that metabonomics is a promising tool to reveal the metabolic changes and the underlying mechanism involved in the pathogenesis of DN.

  17. Polyphenol oxidase activity and antioxidant properties of Yomra apple (Malus communis L.) from Turkey.

    Science.gov (United States)

    Can, Zehra; Dincer, Barbaros; Sahin, Huseyin; Baltas, Nimet; Yildiz, Oktay; Kolayli, Sevgi

    2014-12-01

    In this study, firstly, antioxidant and polyphenol oxidase (PPO) properties of Yomra apple were investigated. Seventeen phenolic constituents were measured by reverse phase-high-performance liquid chromatography (RP-HPLC). Total phenolic compounds (TPCs), ferric reducing antioxidant power (FRAP) and 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activities were performed to measure antioxidant capacity. Some kinetic parameters (Km, Vmax), and inhibition behaviors against five different substrates were measured in the crude extract. Catechin and chlorogenic acid were found as the major components in the methanolic extract, while ferulic acid, caffeic acid, p-hydroxybenzoic acid, quercetin and p-coumaric acid were small quantities. Km values ranged from 0.70 to 10.10 mM in the substrates, and also 3-(4-hydroxyphenyl) propanoic acid (HPPA) and L-DOPA showed the highest affinity. The inhibition constant of Ki were ranged from 0.05 to 14.90 mM against sodium metabisulphite, ascorbic acid, sodium azide and benzoic acid, while ascorbic acid and sodium metabisulphite were the best inhibitors.

  18. Molecular characterization and expression of a novel alcohol oxidase from Aspergillus terreus MTCC6324.

    Directory of Open Access Journals (Sweden)

    Mitun Chakraborty

    Full Text Available The alcohol oxidase (AOx cDNA from Aspergillus terreus MTCC6324 with an open reading frame (ORF of 2001 bp was constructed from n-hexadecane induced cells and expressed in Escherichia coli with a yield of ∼4.2 mg protein g-1 wet cell. The deduced amino acid sequences of recombinant rAOx showed maximum structural homology with the chain B of aryl AOx from Pleurotus eryngii. A functionally active AOx was achieved by incubating the apo-AOx with flavin adenine dinucleotide (FAD for ∼80 h at 16°C and pH 9.0. The isoelectric point and mass of the apo-AOx were found to be 6.5±0.1 and ∼74 kDa, respectively. Circular dichroism data of the rAOx confirmed its ordered structure. Docking studies with an ab-initio protein model demonstrated the presence of a conserved FAD binding domain with an active substrate binding site. The rAOx was specific for aryl alcohols and the order of its substrate preference was 4-methoxybenzyl alcohol >3-methoxybenzyl alcohol>3, 4-dimethoxybenzyl alcohol > benzyl alcohol. A significantly high aggregation to ∼1000 nm (diameter and catalytic efficiency (kcat/Km of 7829.5 min-1 mM-1 for 4-methoxybenzyl alcohol was also demonstrated for rAOx. The results infer the novelty of the AOx and its potential biocatalytic application.

  19. Identification of the NADPH Oxidase 4 Inhibiting Principle of Lycopus europaeus

    Directory of Open Access Journals (Sweden)

    Silvia Revoltella

    2018-03-01

    Full Text Available NADPH oxidase 4 (Nox4 has recently been implicated as driving force in cellular senescence. Thus, there is growing interest to develop Nox4 inhibitors, which might be valuable agents for cosmeceutical applications. Alpine plants represent a valuable source for the identification of novel bioactive natural products with anti-ageing effects, especially substances that protect plants against UV radiation, which is also known to contribute to the ageing of human skin. Therefore, the aim of this study was to identify novel Nox4 inhibitors from alpine plants. Within an initial screening of extracts of alpine plants on their ability to inhibit Nox4 activity in HEK cells, the methanolic extract of the subaerial parts of Lycopus europaeus showed a strong inhibition of Nox4 (81% chemiluminescence quenching and a simultaneously high cell viability (91% vitality. Rosmarinic acid was isolated and identified as the major compound in this bioactive extract. It showed a dose dependent inhibitory activity on Nox4 with an IC50 of 1 µM. Moreover, it also showed a significant inhibitory activity on Nox2 in the low micromolar range, whereas no inhibition of Nox5 was detected. Further investigations confirmed that the observed effects of rosmarinic acid on Nox2 and Nox4 are real inhibitory activities, and not due to ROS scavenging effects. Therefore, L. europaeus, which we demonstrated to be a good source of rosmarinic acid, has great potential for usage in cosmeceutical products with anti-ageing activity.

  20. Preparation of cholesterol oxidase nanoparticles and their application in amperometric determination of cholesterol

    International Nuclear Information System (INIS)

    Chawla, Sheetal; Rawal, Rachna; Sonia; Ramrati; Pundir, C. S.

    2013-01-01

    The nanoparticle (NP) aggregates of commercial cholesterol oxidase (ChOx) were prepared by desolvation method. The formation and characterization of ChOxNP aggregates were studied by transmission electron microscopy and scanning electron microscopy. NP aggregates were more stable, active and had a higher shelf life than that of free enzyme. An amperometric cholesterol biosensor was constructed by immobilizing ChOxNPs onto Au electrode. The biosensor showed optimum response within 8 s at pH 6.0 and 35 °C, when polarized at +0.27 V versus Ag/AgCl. The biosensor possesses high sensitivity and measures cholesterol concentrations as low as 1.56 mg/dl. The working linear range was 12.5–700 mg/dl for cholesterol. The biosensor was evaluated and employed for measurement of total cholesterol in human serum. The enzyme electrode lost 50 % of its initial activity during its regular use for 180 times over a period of 90 days when stored in 0.1 M sodium phosphate buffer, pH 7.0 at 4 °C