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Sample records for sulfone oxidase activity

  1. Electrochemical studies of biocatalytic anode of sulfonated graphene/ferritin/glucose oxidase layer-by-layer biocomposite films for mediated electron transfer.

    Science.gov (United States)

    Inamuddin; Haque, Sufia Ul; Naushad, Mu

    2016-06-01

    In this study, a bioanode was developed by using layer-by-layer (LBL) assembly of sulfonated graphene (SG)/ferritin (Frt)/glucose oxidase (GOx). The SG/Frt biocomposite was used as an electron transfer elevator and mediator, respectively. Glucose oxidase (GOx) from Aspergillus niger was applied as a glucose oxidation biocatalyst. The electrocatalytic oxidation of glucose using GOx modified electrode increases with an increase in the concentration of glucose in the range of 10-50mM. The electrochemical measurements of the electrode was carried out by using cyclic voltammetry (CV) at different scan rates (20-100mVs(-1)) in 30mM of glucose solution prepared in 0.3M potassium ferrocyanide (K4Fe(CN)6) and linear sweep voltammetry (LSV). A saturation current density of 50±2mAcm(-2) at a scan rate of 100mVs(-1) for the oxidation of 30Mm glucose is achieved. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. 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.

  3. New derivatives of 3,4-dihydroisoquinoline-3-carboxylic acid with free-radical scavenging, D-amino acid oxidase, acetylcholinesterase and butyrylcholinesterase inhibitory activity.

    Science.gov (United States)

    Solecka, Jolanta; Guśpiel, Adam; Postek, Magdalena; Ziemska, Joanna; Kawęcki, Robert; Lęczycka, Katarzyna; Osior, Agnieszka; Pietrzak, Bartłomiej; Pypowski, Krzysztof; Wyrzykowska, Agata

    2014-09-30

    A series of 3,4-dihydroisoquinoline-3-carboxylic acid derivatives were synthesised and tested for their free-radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS·+), superoxide anion radical (O2·-) and nitric oxide radical (·NO) assays. We also studied d-amino acid oxidase (DAAO), acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activity. Almost each of newly synthesised compounds exhibited radical scavenging capabilities. Moreover, several compounds showed moderate inhibitory activities against DAAO, AChE and BuChE. Compounds with significant free-radical scavenging activity may be potential candidates for therapeutics used in oxidative-stress-related diseases.

  4. Sulfonated poly(ether sulfone)s containing pyridine moiety for PEMFC.

    Science.gov (United States)

    Jang, Hohyoun; Islam, Md Monirul; Lim, Youngdon; Hossain, Md Awlad; Cho, Younggil; Joo, Hyunho; Kim, Whangi; Jeon, Heung-Seok

    2014-10-01

    Sulfonated poly(ether sulfone)s with varied degree of sulfonation (DS) were prepared via post-sulfonation of synthesized pyridine based poly(ether sulfone) (PPES) using concentrated sulfuric acid as sulfonating agent. The DS was varied with different mole ratio of 4,4'-(2,2-diphenylethenylidene)diphenol, DHTPE in the polymer unit. PPES copolymers were synthesized by direct polycondensation of pyridine unit with bis-(4-fluorophenyl)-sulfone, 4, 4'-sulfonyldiphenol and DHTPE. The structure of the resulting PPES copolymer membranes with different sulfonated units were studied by 1H NMR spectroscopy and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymer with water. The ion exchange capacity (IEC) and proton conductivity were evaluated according to the increase of DS. The water uptake (WU) of the resulting membranes was in the range of 17-58%, compared to that of Nafion 211 28%. The membranes provided proton conductivities of 65-95 mS/cm in contrast to 103 mS/cm of Nafion 211.

  5. 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...

  6. 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.

  7. Bioelectrocatalytic mediatorless dioxygen reduction at carbon ceramic electrodes modified with bilirubin oxidase

    International Nuclear Information System (INIS)

    Nogala, Wojciech; Celebanska, Anna; Szot, Katarzyna; Wittstock, Gunther; Opallo, Marcin

    2010-01-01

    Carbon ceramic electrodes were prepared by sol-gel processing of a hydrophobic precursor - methyltrimethoxysilane (MTMOS) - together with dispersed graphite microparticles according to a literature procedure. Bilirubin oxidase (BOx) was adsorbed on this electrode from buffer solution and this process was followed by atomic force microscopy (AFM). The electrodes exhibited efficient mediatorless electrocatalytic activity towards dioxygen reduction. The activity depends on the time of adsorption of the enzyme and the pH. The electrode remains active in neutral solution. The bioelectrocatalytic activity is further increased when a fraction of the carbon microparticles is replaced by sulfonated carbon nanoparticles (CNPs). This additive enhances the electrical communication between the enzyme and the electronic conductor. At pH 7 the carbon ceramic electrode modified with bilirubin oxidase retains ca. half of its highest activity. The role of the modified nanoparticles is confirmed by experiments in which a film embedded in a hydrophobic silicate matrix also exhibited efficient mediatorless biocatalytic dioxygen reduction. Scanning electrochemical microscopy (SECM) of the studied electrodes indicated a rather even distribution of the catalytic activity over the electrode surface.

  8. Derivatives of phenyl tribromomethyl sulfone as novel compounds with potential pesticidal activity

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    Krzysztof M. Borys

    2012-02-01

    Full Text Available A halogenmethylsulfonyl moiety is incorporated in numerous active herbicides and fungicides. The synthesis of tribromomethyl phenyl sulfone derivatives as novel potential pesticides is reported. The title sulfone was obtained by following three different synthetic routes, starting from 4-chlorothiophenol or 4-halogenphenyl methyl sulfone. Products of its subsequent nitration were subjected to the SNAr reactions with ammonia, amines, hydrazines and phenolates to give 2-nitroaniline, 2-nitrophenylhydrazine and diphenyl ether derivatives. Reduction of the nitro group of 4-tribromomethylsulfonyl-2-nitroaniline yielded the corresponding o-phenylenediamine substrate for preparation of structurally varied benzimidazoles.

  9. 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.)

  10. 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

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

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    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.

  12. 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.

  13. 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

  14. Blood Compatibility of Sulfonated Cladophora Nanocellulose Beads

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    Igor Rocha

    2018-03-01

    Full Text Available Sulfonated cellulose beads were prepared by oxidation of Cladophora nanocellulose to 2,3-dialdehyde cellulose followed by sulfonation using bisulfite. The physicochemical properties of the sulfonated beads, i.e., high surface area, high degree of oxidation, spherical shape, and the possibility of tailoring the porosity, make them interesting candidates for the development of immunosorbent platforms, including their application in extracorporeal blood treatments. A desired property for materials used in such applications is blood compatibility; therefore in the present work, we investigate the hemocompatibility of the sulfonated cellulose beads using an in vitro whole blood model. Complement system activation (C3a and sC5b-9 levels, coagulation activation (thrombin-antithrombin (TAT levels and hemolysis were evaluated after whole blood contact with the sulfonated beads and the results were compared with the values obtained with the unmodified Cladophora nanocellulose. Results showed that neither of the cellulosic materials presented hemolytic activity. A marked decrease in TAT levels was observed after blood contact with the sulfonated beads, compared with Cladophora nanocellulose. However, the chemical modification did not promote an improvement in Cladophora nanocellulose hemocompatibility in terms of complement system activation. Even though the sulfonated beads presented a significant reduction in pro-coagulant activity compared with the unmodified material, further modification strategies need to be investigated to control the complement activation by the cellulosic materials.

  15. Blood Compatibility of Sulfonated Cladophora Nanocellulose Beads.

    Science.gov (United States)

    Rocha, Igor; Lindh, Jonas; Hong, Jaan; Strømme, Maria; Mihranyan, Albert; Ferraz, Natalia

    2018-03-07

    Sulfonated cellulose beads were prepared by oxidation of Cladophora nanocellulose to 2,3-dialdehyde cellulose followed by sulfonation using bisulfite. The physicochemical properties of the sulfonated beads, i.e., high surface area, high degree of oxidation, spherical shape, and the possibility of tailoring the porosity, make them interesting candidates for the development of immunosorbent platforms, including their application in extracorporeal blood treatments. A desired property for materials used in such applications is blood compatibility; therefore in the present work, we investigate the hemocompatibility of the sulfonated cellulose beads using an in vitro whole blood model. Complement system activation (C3a and sC5b-9 levels), coagulation activation (thrombin-antithrombin (TAT) levels) and hemolysis were evaluated after whole blood contact with the sulfonated beads and the results were compared with the values obtained with the unmodified Cladophora nanocellulose. Results showed that neither of the cellulosic materials presented hemolytic activity. A marked decrease in TAT levels was observed after blood contact with the sulfonated beads, compared with Cladophora nanocellulose. However, the chemical modification did not promote an improvement in Cladophora nanocellulose hemocompatibility in terms of complement system activation. Even though the sulfonated beads presented a significant reduction in pro-coagulant activity compared with the unmodified material, further modification strategies need to be investigated to control the complement activation by the cellulosic materials.

  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. 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.

  18. Preparation and characterization of sulfonated amine-poly(ether sulfone)s for proton exchange membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Dong-Wan; Lim, Young-Don; Lee, Soon-Ho; Jeong, Young-Gi; Kim, Whan-Gi [Department of Applied Chemistry/RIC-ReSEM, Konkuk University, Chungju-si, Chungbuk 380-701 (Korea, Republic of); Hong, Tae-Whan [Department of Materials Sci and Engineering/RIC-ReSEM, Chungju National University, Chungju, Chungbuk (Korea, Republic of)

    2010-12-15

    Sulfonated amine-poly(ether sulfone)s (S-APES)s were prepared by nitration, reduction and sulfonation of poly(ether sulfone) (ultrason {sup registered} -S6010). Poly(ether sulfone) was reacted with ammonium nitrate and trifluoroacetic anhydride to produce the nitrated poly(ether sulfone), and was followed by reduction using tin(II)chloride and sodium iodide as reducing agents to give the amino-poly(ether sulfone). The S-APES was obtained by reaction of 1,3-propanesultone and the amino-poly(ether sulfone) (NH{sub 2}-PES) with sodium methoxide. The different degrees of nitration and reduction of poly(ether sulfone) were successfully synthesized by an optimized process. The reduction of nitro group to amino was done quantitatively, and this controlled the contents of the sulfonic acid group. The films were converted from salt to acid forms with dilute hydrochloric acid. Different contents of sulfonated unit of the S-APES were studied by FT-IR, {sup 1}H NMR spectroscopy, differential scanning calorimetry (DSC), and thermo gravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol. The ion exchange capacity (IEC), a measure of proton conductivity, was evaluated. The S-APES membranes exhibit conductivities (25 C) from 1.05 x 10{sup -3} to 4.83 x 10{sup -3} S/cm, water swell from 30.25 to 66.50%, IEC from 0.38 to 0.82 meq/g, and methanol diffusion coefficients from 3.10 x 10{sup -7} to 4.82 x 10{sup -7} cm{sup 2}/S at 25 C. (author)

  19. Synthesis of sulfonated porous carbon nanospheres solid acid by a facile chemical activation route

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Binbin, E-mail: changbinbin806@163.com; Guo, Yanzhen; Yin, Hang; Zhang, Shouren; Yang, Baocheng, E-mail: baochengyang@yahoo.com

    2015-01-15

    Generally, porous carbon nanospheres materials are usually prepared via a template method, which is a multi-steps and high-cost strategy. Here, we reported a porous carbon nanosphere solid acid with high surface area and superior porosity, as well as uniform nanospheical morphology, which prepared by a facile chemical activation with ZnCl{sub 2} using resorcinol-formaldehyde (RF) resins spheres as precursor. The activation of RF resins spheres by ZnCl{sub 2} at 400 °C brought high surface area and large volume, and simultaneously retained numerous oxygen-containing and hydrogen-containing groups due to the relatively low processing temperature. The presence of these functional groups is favorable for the modification of –SO{sub 3}H groups by a followed sulfonation treating with sulphuric acid and organic sulfonic acid. The results of N{sub 2} adsorption–desorption and electron microscopy clearly showed the preservation of porous structure and nanospherical morphology. Infrared spectra certified the variation of surface functional groups after activation and the successful modification of –SO{sub 3}H groups after sulfonation. The acidities of catalysts were estimated by an indirect titration method and the modified amount of –SO{sub 3}H groups were examined by energy dispersive spectra. The results suggested sulfonated porous carbon nanospheres catalysts possessed high acidities and –SO{sub 3}H densities, which endowed their significantly catalytic activities for biodiesel production. Furthermore, their excellent stability and recycling property were also demonstrated by five consecutive cycles. - Graphical abstract: Sulfonated porous carbon nanospheres with high surface area and superior catalytic performance were prepared by a facile chemical activation route. - Highlights: • Porous carbon spheres solid acid prepared by a facile chemical activation. • It owns high surface area, superior porosity and uniform spherical morphology. • It possesses

  20. Plasma diamine oxidase activity in asthmatic children

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    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.

  1. 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.

  2. Side-chain sulfonated poly(ether sulfone)s for PEM applications

    Energy Technology Data Exchange (ETDEWEB)

    Meier-Haack, J.; Butwilowski, W.; Quetschke, A.; Vogel, C. [Leibniz Institute of Polymer Research Dresden, Dresden (Germany)

    2010-07-01

    Copoly(arylene ether sulfone)s from bis-(4-fluoro phenyl)sulfone (DFDPhS), bis(4-trimethylsiloxy phenyl)sulfone (DHDPhS), and 2,5-diphenylhydroquinone trimethylsilylether (Bis-TMS-DPhHQ) were obtained by nucleophilic displacement polycondensation with high molecular weights (M{sub n} up to 70,000 g/mol; {eta}{sub inh} up to 0.93 dl/g) and narrow molecular weight distributions (2.1 - 2.9). All copolymers showed a single glass-transition temperature (T{sub g}) around 230 C. Upon sulfonation with concentrated sulfuric acid, the T{sub g}s (from samples in the protonated form) were shifted to higher temperatures (+ 35 {+-} 5 C). NMR spectra and the determined ion-exchange capacities (IEC; 1.46 - 2.05 mmol/g), which were close to the theoretical values, indicating that only the pendant phenyl rings of the 2,5- diphenylhydroquinone moieties in the polymer backbone were sulfonated. Membranes prepared from N-methyl- 2-pyrrolidone (NMP) solutions were transparent and soft. The water-uptake at room temperature increased from 30% to 80% with increasing IEC. Samples from random copolymers with an IEC {>=} 1.8 mmol/g were soluble in water at 90 C. While the proton conductivity of the low IEC samples (random copolymer) (1.46 mmol/g) was lower than that of Nafion {sup registered}, the conductivities of the high IEC samples were superior to Nafion {sup registered}. In general membranes from blockcopolymers showed lower water-uptake, higher dimensional stability and higher proton conductivities as compared to samples from random copolymers with similar monomer composition and ion-exchange capacities. (orig.)

  3. [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.

  4. Fate of linear alkylbenzene sulfonate (LAS) in activated sludge plants

    NARCIS (Netherlands)

    Temmink, B.G.; Klapwijk, A.

    2004-01-01

    Monitoring data were collected in a pilot-scale municipal activated sludge plant to assess the fate of the C12-homologue of linear alkyl benzene sulfonate (LAS-C12). The pilot-plant was operated at influent LAS-C12 concentrations between 2 and 12 mg/l and at sludge retention times of 10 and 27

  5. Preparation and characterization of proton exchange poly (ether sulfone)s membranes grafted propane sulfonic acid on pendant phenyl groups

    International Nuclear Information System (INIS)

    Lim, Youngdon; Seo, Dongwan; Hossain, Md. Awlad; Lee, Soonho; Lim, Jinseong; Jang, Hohyoun; Hong, Taehoon; Kim,; Kim, Whangi

    2014-01-01

    Poly(ether sulfone)s containing hexaphenyl (PHP) was prepared by 1,2-bis(4-hydroxyphenyl)-3,4,5,6-tetraphenylbenzene, 4,4-hydroxyphenylsulfone, and 4,4-fluorophenylsulfone, followed bromination on phenyl groups to produce brominated PHP (Br-PHP). Grafted sulfonated poly(ether sulfone)s containing hexaphenyl (GSPHP) were prepared from Br-PHP and 3-bromopropane sulfonic acid with potassium salt and copper powder. The salt form was converted to free acid using 1 M sulfuric acid solution. All these membranes were cast from dimethylacetamide (DMAc). The structural properties of the synthesized polymers were investigated by 1 H-NMR spectroscopy. The membranes were studied with regard to ion exchange capacity (IEC), water uptake, Fenton test, and proton conductivity. These grafted polymer membranes were compared with normal sulfonated poly(ether sulfone)s and Nafion

  6. Antimalarial effects of vinyl sulfone cysteine proteinase inhibitors.

    OpenAIRE

    Rosenthal, P J; Olson, J E; Lee, G K; Palmer, J T; Klaus, J L; Rasnick, D

    1996-01-01

    We evaluated the antimalarial effects of vinyl sulfone cysteine proteinase inhibitors. A number of vinyl sulfones strongly inhibited falcipain, a Plasmodium falciparum cysteine proteinase that is a critical hemoglobinase. In studies of cultured parasites, nanomolar concentrations of three vinyl sulfones inhibited parasite hemoglobin degradation, metabolic activity, and development. The antimalarial effects correlated with the inhibition of falcipain. Our results suggest that vinyl sulfones or...

  7. A low perfusion rate microreactor for continuous monitoring of enzyme characteristics : application to glucose oxidase

    NARCIS (Netherlands)

    Posthuma-Trumpie, G. A.; Venema, K.; van Berkel, W. J. H.; Korf, J.

    This report describes a versatile and robust microreactor for bioactive proteins physically immobilized on a polyether sulfone filter. The potential of the reactor is illustrated with glucose oxidase immobilized on a filter with a cut-off value of 30 kDa. A flow-injection system was used to deliver

  8. Synthesis and characterization of sulfonated cardo poly(arylene ether sulfone)s for fuel cell proton exchange membrane application

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M.M.; Jang, H.H.; Lim, Y.D.; Seo, D.W.; Kim, W.G. [Department of Applied Chemistry, Konkuk University, Chungju, Chungbuk (Korea, Republic of); Kim, T.H.; Hong, Y.T. [Energy Material Research Center, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Kim, D.M. [Material Engineering and Science, Hongik Univ, Jochiwon-eup, Yeongi-gun, Chungnam (Korea, Republic of)

    2012-12-15

    Sulfonated cardo poly(arylene ether sulfone)s (SPPA-PES) with various degrees of sulfonation (DS) were prepared by post-sulfonation of synthesized phenolphthalein anilide (PPA; N-phenyl-3,3'-bis(4-hydroxyphenyl)-1-isobenzopyrolidone) poly(arylene ether sulfone)s (PPA-PES) by using concentrated sulfuric acid. PPA-PES copolymers were synthesized by direct polycondensation of PPA with bis-(4-fluorophenyl)-sulfone and 4,4'-sulfonyldiphenol. The DS was varied with different mole ratios of PPA (24, 30, 40, 50 mol.%) in the polymer. The structure of the resulting SPPA-PES copolymers and the different contents of the sulfonated unit were studied by Fourier transform infrared (FT-IR) spectroscopy, {sup 1}H NMR spectroscopy, and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymer with water. The ion exchange capacity (IEC) and proton conductivity of SPPA-PES were evaluated according to the increase of DS. The water uptake (WU) of the resulting SPPA-PES membranes was in the range of 20-72%, compared with 28% for Nafion 211 registered. The SPPA-PES membranes showed proton conductivities of 23-82 mS cm{sup -1}, compared with 194 mS cm{sup -1} for Nafion 211 registered, under 100% relative humidity (RH) at 80 C. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. 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.

  10. 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).

  11. A low perfusion rate microreactor for the continous monitoring of enzyme characteristics: applications for glucose oxidase.

    NARCIS (Netherlands)

    Posthuma-Trumpie, G.A.; Venema, K.; Berkel, van W.J.H.; Korf, J.

    2007-01-01

    This report describes a versatile and robust microreactor for bioactive proteins physically immobilized on a polyether sulfone filter. The potential of the reactor is illustrated with glucose oxidase immobilized on a filter with a cut-off value of 30 kDa. A flow-injection system was used to deliver

  12. 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.

  13. 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.

  14. Thermal and Dielectric Behavior Studies of Poly(Arylene Ether Sulfones with Sulfonated and Phosphonated Pendants

    Directory of Open Access Journals (Sweden)

    Shimoga D. Ganesh

    2016-01-01

    Full Text Available The present paper discusses the aspects of the synthesizing valeric acid based poly(ether sulfones with active carboxylic acid pendants (VALPSU from solution polymerization technique via nucleophilic displacement polycondensation reaction among 4,4′-dichlorodiphenyl sulfone (DCDPS and 4,4′-bis(4-hydroxyphenyl valeric acid (BHPA. The conditions necessary to synthesize and purify the polymer were investigated in some detail. The synthesized poly(ether sulfones comprise sulfone and ether linkages in addition to reactive carboxylic acid functionality; these active carboxylic acid functional groups were exploited to hold the phenyl sulphonic acid and phenyl phosphonic acid pendants. The phenyl sulphonic acid pendants in VALPSU were easily constructed by altering active carboxylic acid moieties by sulfanilic acid using N,N′-dicyclohexylcarbodiimide (DCC mediated mild synthetic route, whereas the latter one was built in two steps. Initially, polyphosphoric acid condensation with VALPSU by 4-bromoaniline and next straightforward palladium catalyzed synthetic route, in both of which acidic pendants are clenched by polymer backbone via amide linkage. Without impairing the primary polymeric backbone modified polymers were prepared by varying the stoichiometric ratios of respective combinations. All the polymers were physicochemically characterized and pressed into tablets; electrical contacts were established to study the dielectric properties. Finally, the influence of the acidic pendants on the dielectric properties was examined.

  15. Synthesis and properties of sulfonated poly(phenylene sulfone)s without ether linkage by Diels–Alder reaction for PEMFC application

    International Nuclear Information System (INIS)

    Lim, Youngdon; Lee, Hyunchul; Lee, Soonho; Jang, Hohyoun; Hossain, Md. Awlad; Cho, Younggil; Kim, Taeho; Hong, Youngtaik; Kim, Whangi

    2014-01-01

    A new sulfonated poly(phenylene sulfone) polymer (SPPS) was synthesized by Diels-Alder polymerization from 1,4-bis(2,4,5-triphenylcyclopentadienone)benzene (BTPCPB) and 4,4′-diethynylphenylsulfone, and followed by sulfonation reaction with chlorosulfuric acid. A series of sulfonated poly(phenylene sulfone)s (SPPS) with different degrees of sulfonation was prepared in a controllable manner with chlorosulfuric acid. These polymers showed good solubility in aprotic polar solvents, dimethyl acetamide (DMAC) and dimethyl sulfoxide (DMSO). Three different polymer membranes were studied by 1 H NMR spectroscopy, and thermogravimetric analysis (TGA). The ion exchange capacity (IEC) and proton conductivity of SPPS were evaluated according to the degrees of sulfonation. The water uptake (WU) of the synthesized SPPS membranes ranged from 38%∼75%, compared with 32% for Nafion 211 ® at 80 °C. The SPPS membranes exhibited proton conductivities (at 80 °C under 90% RH) of 110.2 mS/cm compared with 102.7 mS/cm for Nafion 211 ® . Power density was performed by single cell and showed similar to Nafion value

  16. 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

  17. Paraquat and maneb co-exposure induces noradrenergic locus coeruleus neurodegeneration through NADPH oxidase-mediated microglial activation

    International Nuclear Information System (INIS)

    Hou, Liyan; Zhang, Cong; Wang, Ke; Liu, Xiaofang; Wang, Hongwei; Che, Yuning; Sun, Fuqiang; Zhou, Xueying; Zhao, Xiulan; Wang, Qingshan

    2017-01-01

    Highlights: • Microglial activation induced by paraquat and maneb precedes noradrenergic neurodegeneration in locus coeruleus. • NADPH oxidase activation contributes to microglia-mediated neuroinflammation and related noradrenergic neurodegeneration. • Inhibition of NADPH oxidase by apocynin protects noradrenergic neurons against paraquat and maneb-induced toxicity. - Abstract: Co-exposure to paraquat (PQ) and maneb (Mb) has been shown to increase the risk of Parkinson’s disease (PD) and dopaminergic (DA) neurodegeneration in the substantia nigra pars compacta (SNpc) is observed in PQ and Mb-treated experimental animals. The loss of noradrenergic locus coeruleus (LC/NE) neurons in brainstem is a common feature shared by multiple neurodegenerative diseases, including PD. However, whether PQ and Mb is able to damage LC/NE neurons remains undefined. In this study, mice treated with combined PQ and Mb displayed progressive LC/NE neurodegeneration. Time course studies revealed that the activation of microglia preceded LC/NE neurodegeneration. Mechanistically, the activation of NADPH oxidase contributed to microglial activation and subsequent LC/NE neurodegeneration. We found that PQ and Mb co-exposure induced activation of NADPH oxidase as shown by increased superoxide production and membrane translocation of p47 phox , a cytosolic subunit of NADPH oxidase. Inhibition of NADPH oxidase by apocynin, a widely used NADPH oxidase inhibitor, suppressed microglial activation and gene expressions of proinflammatory factors. Furthermore, reduced activation of nuclear factor-κB (NF-κB) pathway was observed in apocynin-treated mice. More importantly, inhibition of NADPH oxidase by apocynin afforded LC/NE neuroprotection against PQ and Mb-induced neurotoxicity. Thus, our findings revealed the critical role NADPH oxidase-mediated microglial activation in driving LC/NE neurodegeneration induced by PQ and Mb, providing new insights into the pathogenesis of environmental

  18. 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

  19. Antioxidant Activity of Some Plant Extracts Towards Xanthine Oxidase, Lipoxygenase and Tyrosinase

    Directory of Open Access Journals (Sweden)

    Pi-Yu Chen

    2009-08-01

    Full Text Available Natural products have the potential to be developed into new drugs for the treatment of various diseases. The aim of the present study was to screen the antioxidant activities of some common edible fruits, garden plants and medicinal plants indigenous to Taiwan. This was performed by assessing the activities of lipoxygenase, xanthine oxidase and tyrosinase following incubation with extracts from these plants. A further aim was to use HPLC-DAD and tyrosinase to chromatographically identify the antioxidative constituents obtained from an extract exhibiting strong antioxidative properties. The acetone extracts of 27 cultivated plant species from Taiwan were tested for antioxidant activities towards xanthine oxidase, tyrosinase and lipoxygenase using spectrophotometric assays. Koelreuteria henryi, Prunus campanulata, and Rhodiola rosea showed the highest xanthine oxidase inhibitory activities. Camellia sinensis, Rhodiola rosea, and Koelreuteria henryi exhibited good tyrosinase inhibitory activities and potent anti-lipoxygenase activities. As Koelreuteria henryi had notable significant inhibitory activities towards xanthine oxidase, tyrosinase, and lipoxygenase, it was further tested with tyrosinase and HPLC-DAD. The results from this part of the study revealed that the more powerful the antioxidant capability of the extracted component, the greater the decrease in peak height obtained after reacting with tyrosinase. Additional studies are warranted to further characterize the compounds responsible for the antioxidant properties of the examined extracts.

  20. 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.

  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. Radiation-chemical synthesis of polypropylene fabrics with sulfonic acid functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hyun Kug; Park, Jung Soo; Han, Do Hung, E-mail: dhhan@yumail.ac.kr; Bondar, Iuliia, E-mail: juliavad@yahoo.co

    2011-04-01

    A sorption-active material carrying sulfonic acid groups was synthesized by the radiation-induced graft polymerization of styrene monomer onto the surface of non-woven polypropylene fabric, followed by sulfonation of the grafted polystyrene chains. The effect of the main experimental parameters (absorbed dose, monomer concentration, reaction time) on the styrene degree of grafting was investigated. The sulfonation process with 5% chlorosulfonic acid at room temperature was investigated in detail and the optimal sulfonation conditions for the samples with a medium degree of grafting (70-140%) were determined. Densities of 3.5-5 meq/g were obtained by applying those sorption-active PP fabrics with a sulfonic acid group.

  3. The PROMETHEE multiple criteria decision making analysis for selecting the best membrane prepared from sulfonated poly(ether ketone)s and poly(ether sulfone)s for proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Nikouei, Mohammad Ali; Oroujzadeh, Maryam; Mehdipour-Ataei, Shahram

    2017-01-01

    Proton exchange membrane as the heart of fuel cell has been the topic of many research activities in recent years. Finding a suitable alternative for Nafion membranes is one of the most important issues of interest. This study is dedicated to sulfonated poly(ether ketone) and poly(ether sulfone) membranes. For synthesis of these two groups of polymers, two different isomeric biphenols (meta- and para-) were used and each group of membranes with three different degree of sulfonation (25, 35, and 45%) was synthesized. In this way, twelve different membrane samples were obtained and their properties were evaluated. Since each membrane had some strong and some weak points of properties in comparison to the other ones, using a rational analysis for choosing the best membrane between prepared samples was inevitable. For this purpose a PROMETHEE based multiple criteria decision making approach was applied and for evaluation of the weight of each criterion, Shannon entropy method was used. Final results showed that poly(ether ketone) membranes in selected criteria were better than poly(ether sulfone) membranes and as expected, membranes with the highest degree of sulfonation (45%) were placed at the top ranking levels. - Highlights: • Sulfonated poly(ether ketone)s and Poly(ether sulfone)s were synthesized. • Related membranes for PEMFC were prepared. • The properties of membranes were measured. • Multiple criteria decision making approach was used to ranking the membranes. • PROMETHEE based approach selected poly(ether ketone)s as better choices.

  4. Sulfonation of polyester fabrics by gaseous sulfur oxide activated by UV irradiation

    International Nuclear Information System (INIS)

    Kordoghli, Bessem; Khiari, Ramzi; Mhenni, Mohamed Farouk; Sakli, Faouzi; Belgacem, Mohamed Naceur

    2012-01-01

    Highlights: ► In this paper, an original technique was present to improve the hydrophilic properties of polyester fibres. ► The modification of PET fabric was carried out using gaseous sulfur trioxide activated by UV irradiations. ► We fully characterized the modified and untreated fabrics. - Abstract: This paper describes an original technique aiming to improve the hydrophilic properties of polyester fibres. In this method, the sulfonation of the aromatic rings is carried out using gaseous sulfur trioxide activated by UV irradiations. Thus, exposing the polyester textile fabric to the UVC light (wavelength around 254 nm) under a stream of sulfur trioxide leads to the fixation of -SO 3 H groups. The amounts of the fixed sulfonate groups depended on the reaction conditions. Evidence of grafting deduced from the measurements of hygroscopic properties was carried out by contact angle measurement, moisture regain as well as by measuring the rate of retention. SEM and FT-IR analysis, DSC and DTA/TGA thermograms showed that no significant modifications have occurred in the bulk of the treated PET fabrics.

  5. Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China); Wei, Ling [Beijing Center for Physical & Chemical Analysis, Beijing 100089 (China); Liu, Yutong [School of Life Science, Beijing Normal University, Beijing 100875 (China); Liao, Jieying [Department of Translational Medicine, Xiamen Institute of Rare Earth Materials, Chinese Academy of Sciences, Xiamen 361024 (China); Gao, Hui-Ming [Model Animal Research Center of Nanjing University, Nanjing 211800 (China); Zhou, Hui, E-mail: hardhui@gmail.com [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China)

    2017-05-01

    Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm{sup 2} induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm{sup 2}) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91{sup phox}, p47{sup phox} and p40{sup phox}); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47{sup phox} and p67{sup phox} translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to

  6. Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

    International Nuclear Information System (INIS)

    Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin; Wei, Ling; Liu, Yutong; Liao, Jieying; Gao, Hui-Ming; Zhou, Hui

    2017-01-01

    Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm 2 induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm 2 ) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91 phox , p47 phox and p40 phox ); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47 phox and p67 phox translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to oxidative damage to DA neurons. Our

  7. Proton exchange membranes from sulfonated polyetheretherketone and sulfonated polyethersulfone-cardo blends: Conductivity, water sorption and permeation properties

    International Nuclear Information System (INIS)

    Li, Yongli; Nguyen, Quang Trong; Schaetzel, Pierre; Lixon-Buquet, Camille; Colasse, Laurent; Ratieuville, Vincent

    2013-01-01

    Five blend membranes were prepared by solvent evaporation from solutions of the synthesized sulfonated polyetheretherketone (SPEEK) and sulfonated polyethersulfone-cardo (SPESc). Their ion exchange capacity and degree of sulfonation determined by acid–base titration and by thermogravimetric analysis were consistent. The blends glass transition behavior obtained by differential scanning calorimetry suggests that the two sulfonated polymers are compatible in the whole composition range. The values of the activation energy for proton transport determined by conductivity measurements on the SPEEK-based blend membranes were in the range of 13–34 kJ mol −1 , which suggest a mixed transport mechanism that involves both proton jumps on ionic sites and water of hydration and diffusion of proton–water complex in hydrophilic domains. The water vapor sorption in the membranes exhibits sigmoid-shape isotherms which were well fitted by the “new dual mode sorption” model, and the fitted parameters values were successfully used to model the change in the water permeation flux with the upstream water activity using the first Fick's diffusion equation. The fast increase in the permeation flux beyond a critical value of activity (0.5) was owing to the exponential concentration-dependent diffusion coefficient. These modelings allowed us to show a strong increase in the limit diffusion coefficient of water and a decrease in the water-diffusion plasticization coefficient with the SPEEK content in the polymer blends

  8. Synthesis and Antifungal Activity of Novel Sulfone Derivatives Containing 1,3,4-Oxadiazole Moieties

    Directory of Open Access Journals (Sweden)

    Maoguo Tong

    2011-11-01

    Full Text Available A series of new sulfone compounds containing 1,3,4-oxadiazole moieties were synthesized. The structures of these compounds were confirmed by spectroscopic data (IR, 1H- and 13C-NMR and elemental analyses. Antifungal tests indicated that all the title compounds exhibited good antifungal activities against eight kinds of plant pathogenic fungi, and some showed superiority over the commercial fungicide hymexazol. Among them, compounds 5d, 5e, 5f, and 5i showed prominent activity against B. cinerea, with determined EC50 values of 5.21 μg/mL, 8.25 µg/mL, 8.03 µg/mL, and 21.00 µg/mL, respectively. The present work demonstrates that sulfone derivatives such as 5d containing a 1,3,4-oxadiazole moiety can be used as possible lead compounds for the development of potential agrochemicals.

  9. 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.

  10. Clinical Efficacy of Andrographolide Sulfonate in the Treatment of Severe Hand, Foot, and Mouth Disease (HFMD) is Dependent upon Inhibition of Neutrophil Activation.

    Science.gov (United States)

    Wen, Tao; Xu, Wenjun; Liang, Lianchun; Li, Junhong; Ding, Xiaorong; Chen, Xiao; Hu, Jianhua; Lv, Aiping; Li, Xiuhui

    2015-08-01

    Andrographolide sulfonate treatment has been shown to improve clinical severe hand, foot, and mouth disease (HFMD) efficacies when combined with conventional therapy. However, the mechanisms for its therapeutic effects remain elusive. In this study, we aimed to investigate whether andrographolide sulfonate exerts its efficacy by acting on neutrophil activation. We obtained serial plasma samples at two time points (before and after 5 days of therapy) from 28 HFMD patients who received conventional therapy and 18 patients who received combination therapy (andrographolide sulfonate plus conventional therapy). Then, we measured plasma myeloperoxidase (MPO), S100A8/A9, histone, and inflammatory cytokine levels. Furthermore, we examined if andrographolide sulfonate had direct effects on neutrophil activation in vitro. We observed that MPO and S100A8/A9 levels were markedly elevated in the HFMD patients before clinical treatment. At 5 days post-medication, the MPO, S100A8/A9, histone, and interleukin-6 levels were markedly lower in the combination therapy group compared with the conventional therapy group. In vitro studies showed that andrographolide sulfonate inhibited lipopolysaccharide-stimulated neutrophil activation, demonstrated by the decreased production of reactive oxygen species and cytokines. These data indicate that neutrophil activation modulation by andrographolide sulfonate may be a critical determinant for its clinical HFMD treatment efficacy. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  11. 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...

  12. Glycosylation site-targeted PEGylation of glucose oxidase retains native enzymatic activity.

    Science.gov (United States)

    Ritter, Dustin W; Roberts, Jason R; McShane, Michael J

    2013-04-10

    Targeted PEGylation of glucose oxidase at its glycosylation sites was investigated to determine the effect on enzymatic activity, as well as the bioconjugate's potential in an optical biosensing assay. Methoxy-poly(ethylene glycol)-hydrazide (4.5kDa) was covalently coupled to periodate-oxidized glycosylation sites of glucose oxidase from Aspergillus niger. The bioconjugate was characterized using gel electrophoresis, liquid chromatography, mass spectrometry, and dynamic light scattering. Gel electrophoresis data showed that the PEGylation protocol resulted in a drastic increase (ca. 100kDa) in the apparent molecular mass of the protein subunit, with complete conversion to the bioconjugate; liquid chromatography data corroborated this large increase in molecular size. Mass spectrometry data proved that the extent of PEGylation was six poly(ethylene glycol) chains per glucose oxidase dimer. Dynamic light scattering data indicated the absence of higher-order oligomers in the PEGylated GOx sample. To assess stability, enzymatic activity assays were performed in triplicate at multiple time points over the course of 29 days in the absence of glucose, as well as before and after exposure to 5% w/v glucose for 24h. At a confidence level of 95%, the bioconjugate's performance was statistically equivalent to native glucose oxidase in terms of activity retention over the 29 day time period, as well as following the 24h glucose exposure. Finally, the bioconjugate was entrapped within a poly(2-hydroxyethyl methacrylate) hydrogel containing an oxygen-sensitive phosphor, and the construct was shown to respond approximately linearly with a 220±73% signal change (n=4, 95% confidence interval) over the physiologically-relevant glucose range (i.e., 0-400mg/dL); to our knowledge, this represents the first demonstration of PEGylated glucose oxidase incorporated into an optical biosensing assay. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. A durable alternative for proton-exchange membranes: sulfonated poly(benzoxazole thioether sulfone)s

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dan [Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Lab of PEMFC Key Materials and Technologies, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Liaoning, Dalian 116023 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Jinhuan [Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Song, Min-Kyu; Liu, Meilin [Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Yi, Baolian; Zhang, Huamin [Lab of PEMFC Key Materials and Technologies, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Liaoning, Dalian 116023 (China)

    2011-03-18

    To develop a durable proton-exchange membrane (PEM) for fuel-cell applications, a series of sulfonated poly(benzoxazole thioether sulfone)s (SPTESBOs) are designed and synthesized, with anticipated good dimensional stability (via acid-base cross linking), improved oxidative stability against free radicals (via incorporation of thioether groups), and enhanced inherent stability (via elimination of unstable end groups) of the backbone. The structures and the degree of sulfonation of the copolymers are characterized using Fourier-transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy ({sup 1}H NMR and {sup 19}F NMR). The electrochemical stabilities of the monomers are examined using cyclic voltammetry in a typical three-electrode cell configuration. The physicochemical properties of the membranes vital to fuel-cell performance are also carefully evaluated under conditions relevant to fuel-cell operation, including chemical and thermal stability, proton conductivity, solubility in different solvents, water uptake, and swelling ratio. The new membranes exhibit low dimensional change at 25 C to 90 C and excellent thermal stability up to 250 C. Upon elimination of unstable end groups, the co-polymers display enhanced chemical resistance and oxidative stability in Fenton's test. Further, the SPTESBO-HFB-60 (HFB-60=hexafluorobenzene, 60 mol% sulfone) membrane displays comparable fuel-cell performance to that of an NRE 212 membrane at 80 C under fully humidified condition, suggesting that the new membranes have the potential to be more durable but less expensive for fuel-cell applications. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. 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.

  15. [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.

  16. Sulfonation of polyester fabrics by gaseous sulfur oxide activated by UV irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kordoghli, Bessem [Laboratory of Applied Chemical and Environment (UR-CAE) - University of Monastir (Tunisia); Textile Research Laboratory (LRT) - ISET Kasr Hellal, University of Monastir (Tunisia); Khiari, Ramzi, E-mail: khiari_ramzi2000@yahoo.fr [Laboratory of Applied Chemical and Environment (UR-CAE) - University of Monastir (Tunisia); LGP2 - Laboratory of Pulp and Paper Science, 461, Rue de la Papeterie - BP 65, 38402 Saint Martin d' Heres Cedex (France); Mhenni, Mohamed Farouk [Laboratory of Applied Chemical and Environment (UR-CAE) - University of Monastir (Tunisia); Sakli, Faouzi [Textile Research Laboratory (LRT) - ISET Kasr Hellal, University of Monastir (Tunisia); Belgacem, Mohamed Naceur [LGP2 - Laboratory of Pulp and Paper Science, 461, Rue de la Papeterie - BP 65, 38402 Saint Martin d' Heres Cedex (France)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer In this paper, an original technique was present to improve the hydrophilic properties of polyester fibres. Black-Right-Pointing-Pointer The modification of PET fabric was carried out using gaseous sulfur trioxide activated by UV irradiations. Black-Right-Pointing-Pointer We fully characterized the modified and untreated fabrics. - Abstract: This paper describes an original technique aiming to improve the hydrophilic properties of polyester fibres. In this method, the sulfonation of the aromatic rings is carried out using gaseous sulfur trioxide activated by UV irradiations. Thus, exposing the polyester textile fabric to the UVC light (wavelength around 254 nm) under a stream of sulfur trioxide leads to the fixation of -SO{sub 3}H groups. The amounts of the fixed sulfonate groups depended on the reaction conditions. Evidence of grafting deduced from the measurements of hygroscopic properties was carried out by contact angle measurement, moisture regain as well as by measuring the rate of retention. SEM and FT-IR analysis, DSC and DTA/TGA thermograms showed that no significant modifications have occurred in the bulk of the treated PET fabrics.

  17. Sulindac Sulfide, but Not Sulindac Sulfone, Inhibits Colorectal Cancer Growth

    Directory of Open Access Journals (Sweden)

    Christopher S. Williams

    1999-06-01

    Full Text Available Sulindac sulfide, a metabolite of the nonsteroidal antiinflammatory drug (NSAID sulindac sulfoxide, is effective at reducing tumor burden in both familial adenomatous polyposis patients and in animals with colorectal cancer. Another sulindac sulfoxide metabolite, sulindac sulfone, has been reported to have antitumor properties without inhibiting cyclooxygenase activity. Here we report the effect of sulindac sulfone treatment on the growth of colorectal carcinoma cells. We observed that sulindac sulfide or sulfone treatment of HCA-7 cells led to inhibition of prostaglandin E2 production. Both sulindac sulfide and sulfone inhibited HCA-7 and HCT-116 cell growth in vitro. Sulindac sulfone had no effect on the growth of either HCA-7 or HCT-116 xenografts, whereas the sulfide derivative inhibited HCA-7 growth in vivo. Both sulindac sulfide and sulfone inhibited colon carcinoma cell growth and prostaglandin production in vitro, but sulindac sulfone had no effect on the growth of colon cancer cell xenografts in nude mice.

  18. Interrupted reperfusion reduces the activation of NADPH oxidase after cerebral I/R injury.

    Science.gov (United States)

    Shen, Jia; Bai, Xiao-Yin; Qin, Yuan; Jin, Wei-Wei; Zhou, Jing-Yin; Zhou, Ji-Ping; Yan, Ying-Gang; Wang, Qiong; Bruce, Iain C; Chen, Jiang-Hua; Xia, Qiang

    2011-06-15

    Interrupted reperfusion reduces ischemia/reperfusion (I/R) injury. This study was designed to determine whether NADPH oxidase participates in the neural protection against global I/R injury after interrupted reperfusion. Mice were randomly divided into five groups: sham (sham-operated), I/R (20-min global I/R), RR (I/R+interrupted reperfusion), Apo (I/R+apocynin administration), and RR+Apo. Behavioral tests (pole test, beam walking, and Morris water maze) and Nissl staining were undertaken in all five groups; superoxide levels, expression of gp91(phox) and p47(phox), p47(phox) translocation, and Rac1 activation were measured in the sham, I/R, and RR groups. The motor coordination, bradykinesia, and spatial learning and memory, as well as the neuron survival rates, were better in the RR, Apo, and RR+Apo groups than in the I/R group. The NADPH oxidase-dependent superoxide levels, p47(phox) and gp91(phox) expression, p47(phox) translocation, and Rac1 activation were lower in the RR group than in the I/R group. In conclusion, the neural protective effect of interrupted reperfusion is at least partly mediated by decreasing the expression and assembly of NADPH oxidase and the levels of NADPH oxidase-derived superoxide. The most striking reduction Rac1-GTP in the RR group suggests that interrupted reperfusion also acts on the activation of assembled NADPH oxidase by reducing the availability of Rac1-GTP. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. 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)

  20. Auxin-activated NADH oxidase activity of soybean plasma membranes is distinct from the constitutive plasma membrane NADH oxidase and exhibits prion-like properties

    Science.gov (United States)

    Morre, D. James; Morre, Dorothy M.; Ternes, Philipp

    2003-01-01

    The hormone-stimulated and growth-related cell surface hydroquinone (NADH) oxidase activity of etiolated hypocotyls of soybeans oscillates with a period of about 24 min or 60 times per 24-h day. Plasma membranes of soybean hypocotyls contain two such NADH oxidase activities that have been resolved by purification on concanavalin A columns. One in the apparent molecular weight range of 14-17 kDa is stimulated by the auxin herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The other is larger and unaffected by 2,4-D. The 2,4-D-stimulated activity absolutely requires 2,4-D for activity and exhibits a period length of about 24 min. Also exhibiting 24-min oscillations is the rate of cell enlargement induced by the addition of 2,4-D or the natural auxin indole-3-acetic acid (IAA). Immediately following 2,4-D or IAA addition, a very complex pattern of oscillations is frequently observed. However, after several hours a dominant 24-min period emerges at the expense of the constitutive activity. A recruitment process analogous to that exhibited by prions is postulated to explain this behavior.

  1. Synthesis and properties of novel sulfonated poly(arylene ether sulfone) ionomers for vanadium redox flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dongyang; Wang, Shuanjin; Xiao, Min; Meng, Yuezhong [The Key Laboratory of Low-carbon Chemistry and Energy Conservation of Guangdong Province, Institute of Optoelectronic and Functional Composite Materials, Sun Yat-Sen University, Guangzhou 510275 (China)

    2010-12-15

    Novel sulfonated poly(arylene ether sulfone)s with electron-withdrawing sulfone groups in each repeat unit were synthesized via step polymerization followed by post-sulfonation using chlorosulfonic acid. The sulfonation degree can be readily controlled by adjusting the feed ratio of the repeat unit of polymers to chlorosulfonic acid. The synthesized polymers are soluble in common aprotic solvents such as dimethyl sulfoxide, N,N'-dimethylacetamide and dimethylformamide, and can be cast into transparent membranes from their solutions. The ion exchange capacity, water uptake, swelling ratio, sulfonation degree, mechanical property, oxidative property, thermal property and proton conductivity were investigated in detail using different methodologies. As an objective to apply these polymers as separators for vanadium redox flow battery, the VO{sup 2+} permeability and cell performance for the single cell were examined and assessed. (author)

  2. Synthesis and properties of novel sulfonated poly(arylene ether sulfone) ionomers for vanadium redox flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dongyang [Key Laboratory of Low-carbon Chemistry and Energy Conservation of Guangdong Province, Institute of Optoelectronic and Functional Composite Materials, Sun Yat-Sen University, Guangzhou 510275 (China); Wang Shuanjin, E-mail: wangshj@mail.sysu.edu.c [Key Laboratory of Low-carbon Chemistry and Energy Conservation of Guangdong Province, Institute of Optoelectronic and Functional Composite Materials, Sun Yat-Sen University, Guangzhou 510275 (China); Xiao Min [Key Laboratory of Low-carbon Chemistry and Energy Conservation of Guangdong Province, Institute of Optoelectronic and Functional Composite Materials, Sun Yat-Sen University, Guangzhou 510275 (China); Meng Yuezhong, E-mail: mengyzh@mail.sysu.edu.c [Key Laboratory of Low-carbon Chemistry and Energy Conservation of Guangdong Province, Institute of Optoelectronic and Functional Composite Materials, Sun Yat-Sen University, Guangzhou 510275 (China)

    2010-12-15

    Novel sulfonated poly(arylene ether sulfone)s with electron-withdrawing sulfone groups in each repeat unit were synthesized via step polymerization followed by post-sulfonation using chlorosulfonic acid. The sulfonation degree can be readily controlled by adjusting the feed ratio of the repeat unit of polymers to chlorosulfonic acid. The synthesized polymers are soluble in common aprotic solvents such as dimethyl sulfoxide, N,N'-dimethylacetamide and dimethylformamide, and can be cast into transparent membranes from their solutions. The ion exchange capacity, water uptake, swelling ratio, sulfonation degree, mechanical property, oxidative property, thermal property and proton conductivity were investigated in detail using different methodologies. As an objective to apply these polymers as separators for vanadium redox flow battery, the VO{sup 2+} permeability and cell performance for the single cell were examined and assessed.

  3. Extreme ultraviolet (EUV) degradation of poly(olefin sulfone)s: Towards applications as EUV photoresists

    International Nuclear Information System (INIS)

    Lawrie, Kirsten; Blakey, Idriss; Blinco, James; Gronheid, Roel; Jack, Kevin; Pollentier, Ivan; Leeson, Michael J.; Younkin, Todd R.; Whittaker, Andrew K.

    2011-01-01

    Poly(olefin sulfone)s, formed by the reaction of sulfur dioxide (SO 2 ) and an olefin, are known to be highly susceptible to degradation by radiation and thus have been identified as candidate materials for chain scission-based extreme ultraviolet lithography (EUVL) resist materials. In order to investigate this further, the synthesis and characterisation of two poly(olefin sulfone)s namely poly(1-pentene sulfone) (PPS) and poly(2-methyl-1-pentene sulfone) (PMPS), was achieved and the two materials were evaluated for possible chain scission EUVL resist applications. It was found that both materials possess high sensitivities to EUV photons; however; the rates of outgassing were extremely high. The only observed degradation products were found to be SO 2 and the respective olefin suggesting that depolymerisation takes place under irradiation in a vacuum environment. In addition to depolymerisation, a concurrent conversion of SO 2 moieties to a sulfide phase was observed using XPS.

  4. 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

  5. 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.

  6. Well-Shaped Sulfonic Organosilica Nanotubes with High Activity for Hydrolysis of Cellobiose

    Directory of Open Access Journals (Sweden)

    Jing Sun

    2017-04-01

    Full Text Available Sulfonic organosilica nanotubes with different acidity densities could be synthesized through the co-condensation of ethenyl- or phenylene-bridged organosilane and 3-mercaptopropyltrimethoxysilane followed by sulfhydryl (–SH oxidation. Transmission electron microscopy (TEM analysis and nitrogen adsorption-desorption experiment clearly exhibit the hollow nanotube structures with the diameters of about 5 nm. The compositions of the nanotube frameworks are confirmed by solid state 13C nuclear magnetic resonance (NMR while X-ray photoelectron spectroscopy (XPS shows that about 60–80% of SH groups were oxidized to sulfonic acid (SO3H. The acid contents were measured by both elemental analysis (CHNS mode and acid-base titration experiment, which revealed that the acid density was in the range of 0.74 to 4.37 μmol·m−2 on the solid. These nanotube-based acid catalysts exhibited excellent performances in the hydrolysis of cellobiose with the highest conversion of 92% and glucose selectivity of 96%. In addition, the catalysts could maintain high activity (65% conversion with 92% selectivity even after six recycles.

  7. 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)

  8. 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 ...

  9. Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jian-Ching; Rebrin, Igor [Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (United States); Klichko, Vladimir; Orr, William C. [Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275 (United States); Sohal, Rajindar S., E-mail: sohal@usc.edu [Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (United States)

    2010-10-08

    Research highlights: {yields} Cytochrome c oxidase loses catalytic activity during the aging process. {yields} Abundance of seven nuclear-encoded subunits of cytochrome c oxidase decreased with age in Drosophila. {yields} Cytochrome c oxidase is specific intra-mitochondrial site of age-related deterioration. -- Abstract: The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H{sub 2}O{sub 2} generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle-, and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc, and VIII, indicated that the abundance these polypeptides decreased, ranging from 11% to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology.

  10. Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Ren, Jian-Ching; Rebrin, Igor; Klichko, Vladimir; Orr, William C.; Sohal, Rajindar S.

    2010-01-01

    Research highlights: → Cytochrome c oxidase loses catalytic activity during the aging process. → Abundance of seven nuclear-encoded subunits of cytochrome c oxidase decreased with age in Drosophila. → Cytochrome c oxidase is specific intra-mitochondrial site of age-related deterioration. -- Abstract: The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H 2 O 2 generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle-, and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc, and VIII, indicated that the abundance these polypeptides decreased, ranging from 11% to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology.

  11. Bisphenol A sulfonation is impaired in metabolic and liver disease

    International Nuclear Information System (INIS)

    Yalcin, Emine B.; Kulkarni, Supriya R.; Slitt, Angela L.; King, Roberta

    2016-01-01

    Background: Bisphenol A (BPA) is a widely used industrial chemical and suspected endocrine disruptor to which humans are ubiquitously exposed. The liver metabolizes and facilitates BPA excretion through glucuronidation and sulfonation. The sulfotransferase enzymes contributing to BPA sulfonation (detected in human and rodents) is poorly understood. Objectives: To determine the impact of metabolic and liver disease on BPA sulfonation in human and mouse livers. Methods: The capacity for BPA sulfonation was determined in human liver samples that were categorized into different stages of metabolic and liver disease (including obesity, diabetes, steatosis, and cirrhosis) and in livers from ob/ob mice. Results: In human liver tissues, BPA sulfonation was substantially lower in livers from subjects with steatosis (23%), diabetes cirrhosis (16%), and cirrhosis (18%), relative to healthy individuals with non-fatty livers (100%). In livers of obese mice (ob/ob), BPA sulfonation was lower (23%) than in livers from lean wild-type controls (100%). In addition to BPA sulfonation activity, Sult1a1 protein expression decreased by 97% in obese mouse livers. Conclusion: Taken together these findings establish a profoundly reduced capacity of BPA elimination via sulfonation in obese or diabetic individuals and in those with fatty or cirrhotic livers versus individuals with healthy livers. - Highlights: • Present study demonstrates that hepatic SULT 1A1/1A3 are primarily sulfonate BPA in mouse and human. • Hepatic BPA sulfonation is profoundly reduced steatosis, diabetes and cirrhosis. • With BPA-S detectable in urine under low or common exposures, these findings are novel and important.

  12. Bisphenol A sulfonation is impaired in metabolic and liver disease

    Energy Technology Data Exchange (ETDEWEB)

    Yalcin, Emine B.; Kulkarni, Supriya R.; Slitt, Angela L., E-mail: angela_slitt@uri.edu; King, Roberta, E-mail: rking@uri.edu

    2016-02-01

    Background: Bisphenol A (BPA) is a widely used industrial chemical and suspected endocrine disruptor to which humans are ubiquitously exposed. The liver metabolizes and facilitates BPA excretion through glucuronidation and sulfonation. The sulfotransferase enzymes contributing to BPA sulfonation (detected in human and rodents) is poorly understood. Objectives: To determine the impact of metabolic and liver disease on BPA sulfonation in human and mouse livers. Methods: The capacity for BPA sulfonation was determined in human liver samples that were categorized into different stages of metabolic and liver disease (including obesity, diabetes, steatosis, and cirrhosis) and in livers from ob/ob mice. Results: In human liver tissues, BPA sulfonation was substantially lower in livers from subjects with steatosis (23%), diabetes cirrhosis (16%), and cirrhosis (18%), relative to healthy individuals with non-fatty livers (100%). In livers of obese mice (ob/ob), BPA sulfonation was lower (23%) than in livers from lean wild-type controls (100%). In addition to BPA sulfonation activity, Sult1a1 protein expression decreased by 97% in obese mouse livers. Conclusion: Taken together these findings establish a profoundly reduced capacity of BPA elimination via sulfonation in obese or diabetic individuals and in those with fatty or cirrhotic livers versus individuals with healthy livers. - Highlights: • Present study demonstrates that hepatic SULT 1A1/1A3 are primarily sulfonate BPA in mouse and human. • Hepatic BPA sulfonation is profoundly reduced steatosis, diabetes and cirrhosis. • With BPA-S detectable in urine under low or common exposures, these findings are novel and important.

  13. 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.

  14. Activation of NADPH oxidase mediates increased endoplasmic reticulum stress and left ventricular remodeling after myocardial infarction in rabbits.

    Science.gov (United States)

    Li, Bao; Tian, Jing; Sun, Yi; Xu, Tao-Rui; Chi, Rui-Fang; Zhang, Xiao-Li; Hu, Xin-Ling; Zhang, Yue-An; Qin, Fu-Zhong; Zhang, Wei-Fang

    2015-05-01

    Nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidase activity and endoplasmic reticulum (ER) stress are increased after myocardial infarction (MI). In this study, we proposed to test whether activation of the NADPH oxidase in the remote non-infarcted myocardium mediates ER stress and left ventricular (LV) remodeling after MI. Rabbits with MI or sham operation were randomly assigned to orally receive an NADPH oxidase inhibitor apocynin or placebo for 30 days. The agents were administered beginning at 1 week after surgery. MI rabbits exhibited decreases in LV fractional shortening, LV ejection fraction and the first derivative of the LV pressure rise, which were abolished by apocynin treatment. NADPH oxidase Nox2 protein and mRNA expressions were increased in the remote non-infarcted myocardium after MI. Immunolabeling further revealed that Nox2 was increased in cardiac myocytes in the remote myocardium. The apocynin treatment prevented increases in the Nox2 expression, NADPH oxidase activity, oxidative stress, myocyte apoptosis and GRP78, CHOP and cleaved caspase 12 protein expression in the remote myocardium. The apocynin treatment also attenuated increases in myocyte diameter and cardiac fibrosis. In cultured H9C2 cardiomyocytes exposed to angiotensin II, an important stimulus for post-MI remodeling, Nox2 knockdown with siRNA significantly inhibited angiotensin II-induced NADPH oxidase activation, reactive oxygen species and GRP78 and CHOP protein expression. We conclude that NADPH oxidase inhibition attenuates increased ER stress in the remote non-infarcted myocardium and LV remodeling late after MI in rabbits. These findings suggest that the activation of NADPH oxidase in the remote non-infarcted myocardium mediates increased ER stress, contributing to myocyte apoptosis and LV remodeling after MI. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Boosting the oxidase mimicking activity of nanoceria by fluoride capping: rivaling protein enzymes and ultrasensitive F- detection

    Science.gov (United States)

    Liu, Biwu; Huang, Zhicheng; Liu, Juewen

    2016-07-01

    Nanomaterial-based enzyme mimics (nanozymes) are currently a new forefront of chemical research. However, the application of nanozymes is limited by their low catalytic activity and low turnover numbers. Cerium dioxide nanoparticles (nanoceria) are among the few with oxidase activity. Herein, we report an interesting finding addressing their limitations. The oxidase activity of nanoceria is improved by over 100-fold by fluoride capping, making it more close to real oxidases. The turnover number reached 700 in 15 min, drastically improved from ~15 turnovers for the naked particles. The mechanism is attributed to surface charge modulation and facilitated electron transfer by F- capping based on ζ-potential and free radical measurements. Ultrasensitive sensing of fluoride was achieved with a detection limit of 0.64 μM F- in water and in toothpastes, while no other tested anions can achieve the activity enhancement.Nanomaterial-based enzyme mimics (nanozymes) are currently a new forefront of chemical research. However, the application of nanozymes is limited by their low catalytic activity and low turnover numbers. Cerium dioxide nanoparticles (nanoceria) are among the few with oxidase activity. Herein, we report an interesting finding addressing their limitations. The oxidase activity of nanoceria is improved by over 100-fold by fluoride capping, making it more close to real oxidases. The turnover number reached 700 in 15 min, drastically improved from ~15 turnovers for the naked particles. The mechanism is attributed to surface charge modulation and facilitated electron transfer by F- capping based on ζ-potential and free radical measurements. Ultrasensitive sensing of fluoride was achieved with a detection limit of 0.64 μM F- in water and in toothpastes, while no other tested anions can achieve the activity enhancement. Electronic supplementary information (ESI) available: Methods, TMB oxidation kinetics and control experiments. See DOI: 10.1039/c6nr02730j

  16. A new methodology for the determination of enzyme activity based on carbon nanotubes and glucose oxidase.

    Science.gov (United States)

    Yeşiller, Gülden; Sezgintürk, Mustafa Kemal

    2015-11-10

    In this research, a novel enzyme activity analysis methodology is introduced as a new perspective for this area. The activity of elastase enzyme, which is a digestive enzyme mostly of found in the digestive system of vertebrates, was determined by an electrochemical device composed of carbon nanotubes and a second enzyme, glucose oxidase, which was used as a signal generator enzyme. In this novel methodology, a complex bioactive layer was constructed by using carbon nanotubes, glucose oxidase and a supporting protein, gelatin on a solid, conductive substrate. The activity of elastase was determined by monitoring the hydrolysis rate of elastase enzyme in the bioactive layer. As a result of this hydrolysis of elastase, glucose oxidase was dissociated from the bioactive layer, and following this the electrochemical signal due to glucose oxidase was decreased. The progressive elastase-catalyzed digestion of the bioactive layer containing glucose oxidase decreased the layer's enzymatic efficiency, resulting in a decrease of the glucose oxidation current as a function of the enzyme activity. The ratio of the decrease was correlated to elastase activity level. In this study, optimization experiments of bioactive components and characterization of the resulting new electrochemical device were carried out. A linear calibration range from 0.0303U/mL to 0.0729U/mL of elastase was reported. Real sample analyses were also carried out by the new electrochemical device. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Sulfonation of PEEK-WC polymer via chloro-sulfonic acid for potential PEM fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Iulianelli, A.; Clarizia, G.; Gugliuzza, A.; Ebrasu, D.; Basile, A. [Institute on Membrane Technology, ITM-CNR, c/o University of Calabria, Via P. Bucci, Cubo 17/C, 87030 Rende (CS) (Italy); Bevilacqua, A. [Research Centre Italsistemi S.r.l., Via Avogadro, 88900 Crotone (KR) (Italy); Trotta, F. [Department of Organic Chemistry, University of Torino, C.So M. D' Azeglio 48, 10125 Torino (TO) (Italy)

    2010-11-15

    The preparation and characterization of thin dense sulfonated poly-ether-ether-ketone with cardo group (PEEK-WC) membranes for proton exchange membrane fuel cell (PEMFC) applications are described. The sulfonation of PEEK-WC polymer was realized via chloro-sulfonic acid and different kinds of membrane samples were prepared with a sulfonation degree ranging from 67 to 99%. The degree of sulfonation, homogeneity and thickness significantly affect both the membrane transport properties and the electrochemical performances. The dense character of the membranes was confirmed by SEM analysis. Proton conductivity measurements were carried out in a temperature range from 30 to 80 C and at 100% of relative humidity, reaching 5.40 x 10{sup -3} S/cm{sup -1} as best value at 80 C and with a sulfonation degree (DS) of 99%. At the same conditions, a water uptake of 17% was achieved. DSC and TGA characterizations were used in order to determine the thermal stability of the membranes, confirming a T{sub g} ranging between 206 and 216 C depending on the DS, whereas FT-IR yielded indication about intermolecular interactions and water uptake at various sulfonation degrees. (author)

  18. Propagation/depropagation equilibrium and structural factors in the radiation degradation of poly(olefin sulfone)s

    International Nuclear Information System (INIS)

    Bowmer, T.N.; O'Donnell, J.H.

    1981-01-01

    The principal volatile products observed after γ irradiation of nine different poly(olefin sulfone)s in the solid state were the two comonomers, i.e., the respective olefin and sulfur dioxide. An exponential increase in yield, G (volatile products), with increasing irradiation temperature, T/sub irr/, was observed for each copolymer through the ceiling temperature, T/sub c/, for the corresponding propagation/depropagation equilibrium. Thus the G value increased by ca. 3 orders of magnitude from T/sub irr/ = 0.7 T/sub c/ to T/sub irr/ = 1.3 T/sub c/ for all of the poly(olefin sulfone)s. Depropagation sensitivity was considered to be best measured by G(SO 2 ) since radiation induced, cationic homopolymerization of the product olefin occurred to a variable extent. Five of the poly(olefin sulfone)s had similar rates of depropagation at their respective T/sub c's/ but the polysulfones of 1-hexene, cyclohexene and 2-butene showed anomalously high depropagation rates. This may be related to greater steric hinderance to segmental chain mobility in the polysulfones of the 1,2 disubstituted olefins. Poly(1-hexene sulfone) appears to be anomalous, as in other respects

  19. Season-controlled changes in biochemical constituents and oxidase enzyme activities in tomato (Lycopersicon esculentum Mill.).

    Science.gov (United States)

    Sen, Supatra; Mukherji, S

    2009-07-01

    Season-controlled changes in biochemical constituents viz. carotenoids (carotene and xanthophyll) and pectic substances along with IAA-oxidase and polyphenol oxidase (PPO) enzyme activities were estimated/assayed in leaves of Lycopersicon esculentum Mill. (tomato) in two developmental stages--pre-flowering (35 days after sowing) and post-flowering (75 days after sowing) in three different seasons--summer rainy and winter Carotenoid content along with pectic substances were highest in winter and declined significantly in summer followed by rainy i.e. winter > summer > rainy. Carotenoid content was significantly higher in the pre-flowering as compared to post-flowering in all three seasons while pectic substances increased in the post-flowering as compared to pre-flowering throughout the annual cycle. IAA oxidase and PPO enzyme activities were enhanced in rainy and decreased sharply in summer and winter i.e. rainy > summer > winter. Both the enzymes exhibited higher activity in the post-flowering stage as compared to pre-flowering in all three seasons. These results indicate winter to be the most favourable season for tomato plants while rainy season environmental conditions prove to be unfavourable (stressful) with diminished content of carotenoid and pectic substances and low activities of IAA oxidase and PPO, ultimately leading to poor growth and productivity.

  20. Andrographolide sulfonate ameliorates experimental colitis in mice by inhibiting Th1/Th17 response.

    Science.gov (United States)

    Liu, Wen; Guo, Wenjie; Guo, Lele; Gu, Yanhong; Cai, Peifen; Xie, Ning; Yang, Xiaoling; Shu, Yongqian; Wu, Xuefeng; Sun, Yang; Xu, Qiang

    2014-06-01

    Inflammatory bowel disease (IBD) is a chronic, relapsing and remitting condition of inflammation involves overproduction of pro-inflammatory cytokines and excessive functions of inflammatory cells. However, current treatments for IBD may have potential adverse effects including steroid dependence, infections and lymphoma. Therefore new therapies for the treatment of IBD are desperately needed. In the present study, we aimed to examine the effect of andrographolide sulfonate, a water-soluble form of andrographolide (trade name: Xi-Yan-Ping Injection), on murine experimental colitis induced by 2, 4, 6-trinitrobenzene sulfonic acid (TNBS). Andrographolide sulfonate was administrated through intraperitoneal injection to mice with TNBS-induced colitis. TNBS-induced body weight loss, myeloperoxidase activity, shortening of the colon and colonic inflammation were significantly ameliorated by andrographolide sulfonate. Both the mRNA and protein levels of pro-inflammatory cytokines were reduced by andrographolide sulfonate administration. Moreover, andrographolide sulfonate markedly suppressed the activation of p38 mitogen-activated protein kinase as well as p65 subunit of nuclear factor-κB (NF-κB). Furthermore, CD4(+) T cell infiltration as well as the differentiation of Th1 (CD4(+)IFN-γ(+)) and Th17 (CD4(+)IL17A(+)) subset were inhibited by andrographolide sulfonate. In summary, these results suggest that andrographolide sulfonate ameliorated TNBS-induced colitis in mice through inhibiting Th1/Th17 response. Our study shows that water-soluble andrographolide sulfonate may represent a new therapeutic approach for treating gastrointestinal inflammatory disorders. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Analytical methodology for sulfonated lignins

    NARCIS (Netherlands)

    Brudin, S.; Schoenmakers, P.

    2010-01-01

    There is a significant need to characterize and classify lignins and sulfonated lignins. Lignins have so far received a good deal of attention, whereas this is not true for sulfonated lignins. There is a clear demand for a better understanding of sulfonated lignins on a chemical as well as physical

  2. Evaluation of Antimicrobial Activity of Glucose Oxidase from Aspergillus niger EBL-A and Penicillium notatum

    Directory of Open Access Journals (Sweden)

    Muhammad Anjum Zia

    2013-12-01

    Full Text Available This work aimed to study the production and purification of glucose oxidase by Aspergillus niger and Penicillium notatum using corn steep liquor as the substrate and evaluate its antimicrobial activity for use in pharmaceutical and food industries. The enzyme was purified by ammonium sulfate precipitation (60-85%, DEAE-cellulose ion exchange and Sephadex G-200 size exclusion chromatography. The crude enzyme extracts of A. niger and P. notatum showed 2.32 and 5.53 U mg-1 specific activities, respectively, which after desalting was 15.52 and 12.05 U mg-1, and after ion exchange and gel filtration chromatography was 29.09 - 62 and 25.72 - 59.37 U mg-1 for A. niger and P. notatum, respectively. The antimicrobial activity was determined by disc diffusion method against selected microbial strains where glucose oxidase from A. niger showed anti-bacterial activity, while no fungicidal effects were shown by both A. niger and P. notatum glucose oxidases.

  3. Synthesis, structural, solubility and anticancer activity studies of salts using nucleobases and sulfonic acids coformer

    Science.gov (United States)

    Singh, Neetu; Singh, Udai P.; Nikhil, Kumar; Roy, Partha; Singh, Hariji

    2017-10-01

    The reactions of natural and unnatural nucleobases (cytosine (Cyt), adenine (Ade), 5-aminouracil (AU) and caffeine (Caff)) with sulfonic acids coformer (1,5-naphthalenedisulfonic acid, NDSA; 5-sulfosalicylic acid, SSA) resulted in the formation of salts viz. [NDSA.Cyt] (1), [NDSA.Ade] (2), [NDSA.AU] (3), [NDSA.Caff] (4), [SSA.Cyt] (5), [SSA.Ade] (6), [SSA.AU] (7), and [SSA.Caff] (8). The structural analysis revealed that salts 1, 4, 6 and 7 have intermolecular interactions between adjacent nucleobases which form two different homodimer shown in R22 (8) motif and assembled via complementary Nsbnd H⋯O and Nsbnd H⋯N interactions. However, in all other salts an intermediate supramolecular synthon pattern was observed between nucleobases and sulfonic acids. The lattice energy was also calculated by DFT to investigate whether salts were thermodynamically more stable than its coformer. The same was further confirmed by differential scanning calorimetry-thermogravimetric (DSC-TG) analysis. The anticancer activity study of individual nucleobases and their NDSA salts were also performed on human breast (MCF-7) and lung (A 549) cancer cell. The salts formation of nucleobases with sulfonic acids improved their solubility, thereby demonstrating up to 8-fold increase in solubility of nucleobases.

  4. 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.

  5. Comparison of brain mitochondrial cytochrome c oxidase activity with cyanide LD(50) yields insight into the efficacy of prophylactics.

    Science.gov (United States)

    Marziaz, Mandy L; Frazier, Kathryn; Guidry, Paul B; Ruiz, Robyn A; Petrikovics, Ilona; Haines, Donovan C

    2013-01-01

    Cyanide inhibits cytochrome c oxidase, the terminal oxidase of the mitochondrial respiratory pathway, therefore inhibiting the cell oxygen utilization and resulting in the condition of histotoxic anoxia. The enzyme rhodanese detoxifies cyanide by utilizing sulfur donors to convert cyanide to thiocyanate, and new and improved sulfur donors are actively sought as researchers seek to improve cyanide prophylactics. We have determined brain cytochrome c oxidase activity as a marker for cyanide exposure for mice pre-treated with various cyanide poisoning prophylactics, including sulfur donors thiosulfate (TS) and thiotaurine (TT3). Brain mitochondria were isolated by differential centrifugation, the outer mitochondrial membrane was disrupted by a maltoside detergent, and the decrease in absorbance at 550 nm as horse heart ferrocytochrome c (generated by the dithiothreitol reduction of ferricytochrome c) was oxidized was monitored. Overall, the TS control prophylactic treatment provided significant protection of the cytochrome c oxidase activity. The TT3-treated mice showed reduced cytochrome c oxidase activity even in the absence of cyanide. In both treatment series, addition of exogenous Rh did not significantly enhance the prevention of cytochrome c oxidase inhibition, but the addition of sodium nitrite did. These findings can lead to a better understanding of the protection mechanism by various cyanide antidotal systems. Copyright © 2011 John Wiley & Sons, Ltd.

  6. 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.

  7. 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)

  8. Synthesis, Antibacterial and Antitubercular Activities of Some 5H-Thiazolo[3,2-a]pyrimidin-5-ones and Sulfonic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Dong Cai

    2015-09-01

    Full Text Available A series of 5H-thiazolo[3,2-a]pyrimidin-5-ones were synthesized by the cyclization reactions of S-alkylated derivatives in concentrated H2SO4. Upon treatment of S-alkylated derivatives at different temperatures, intramolecular cyclization to 7-(substituted phenylamino-5H-thiazolo[3,2-a]pyrimidin-5-ones or sulfonation of cyclized products to sulfonic acid derivatives occurred. The structures of the target compounds were confirmed by IR, 1H-NMR, 13C-NMR and HRMS studies. The compounds were evaluated for their preliminary in vitro antibacterial activity against some Gram-positive and Gram-negative bacteria and screened for antitubercular activity against Mycobacterium tuberculosis by the broth dilution assay method. Some compounds showed good antibacterial and antitubercular activities.

  9. ASIC-like currents in freshly isolated cerebral artery smooth muscle cells are inhibited by endogenous oxidase activity.

    Science.gov (United States)

    Chung, Wen-Shuo; Farley, Jerry M; Drummond, Heather A

    2011-01-01

    The aim of this study was to determine if VSMC ASIC-like currents are regulated by oxidative state. We used whole-cell patch clamp of isolated mouse cerebral VSMCs to determine if 1) reducing agents, such as DTT and GSH, and 2) inhibition of endogenous oxidase activity from NADPH and Xanthine oxidases potentiate active currents and activate electrically silent currents. Pretreatment with 2 mM DTT or GSH, increased the mean peak amplitude of ASIC-like currents evoked by pH 6.0 from 0.4 ± 0.1 to 14.9 ± 3.6 pA/pF, and from 0.9 ± 0.3 to 11.3 ± 2.4 pA/pF, respectively. Pretreatment with apocynin, a NADPH oxidase inhibitor, mimics the effect of the reducing agents, with the mean peak current amplitude increased from 0.9 ± 0.5 to 7.0 ± 2.6 pA/pF and from 0.5 ± 0.2 to 26.4 ± 6.8 pA/pF by 50 and 200 μM apocynin, respectively. Pretreatment with allopurinol, a xanthine oxidase inhibitor, also potentiates the VSMC ASIC-like activity. These findings suggest that VSMC ASIC-like channels are regulated by oxidative state and may be inhibited by basal endogenous oxidative sources such as NADPH and xanthine oxidase. Copyright © 2011 S. Karger AG, Basel.

  10. 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.

  11. Effects of phenylated compounds of methylglyoxal bis(guanylhydrazone) on diamine oxidase activity from rat small intestine.

    Science.gov (United States)

    Balaña-Fouce, R; Pulido, T G; Escudero, D O; Sanz-Sanchez, F

    1986-01-01

    Two phenylated compounds of methylglyoxal bis(guanylhydrazone), potentially inhibitors of diamine oxidase activity, have been synthesized: phenylglyoxal bis(guanylhydrazone) and diphenylglyoxal bis(guanylhydrazone). Their inhibitory capacity was tested: while PGBG was able to reduce the enzyme activity by 50% at 1.3 microM, DPGBG was only able to reduce diamine oxidase activity by less than 2% at a concentration 1000-fold higher. The inhibition of PGBG was non-competitive and the Ki calculated by a Dixon plot was estimated as 1.7 microM.

  12. 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.

  13. Priming of the neutrophil NADPH oxidase activation: role of p47phox phosphorylation and NOX2 mobilization to the plasma membrane.

    Science.gov (United States)

    El-Benna, Jamel; Dang, Pham My-Chan; Gougerot-Pocidalo, Marie-Anne

    2008-07-01

    Neutrophils play an essential role in host defense against microbial pathogens and in the inflammatory reaction. Upon activation, neutrophils produce superoxide anion (O*2), which generates other reactive oxygen species (ROS) such as hydrogen peroxide (H2O2), hydroxyl radical (OH*) and hypochlorous acid (HOCl), together with microbicidal peptides and proteases. The enzyme responsible for O2* production is called the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase or respiratory burst oxidase. This multicomponent enzyme system is composed of two trans-membrane proteins (p22phox and gp91phox/NOX2, which form the cytochrome b558), three cytosolic proteins (p47phox, p67phox, p40phox) and a GTPase (Rac1 or Rac2), which assemble at membrane sites upon cell activation. NADPH oxidase activation in phagocytes can be induced by a large number of soluble and particulate factors. Three major events accompany NAPDH oxidase activation: (1) protein phosphorylation, (2) GTPase activation, and (3) translocation of cytosolic components to the plasma membrane to form the active enzyme. Actually, the neutrophil NADPH oxidase exists in different states: resting, primed, activated, or inactivated. The resting state is found in circulating blood neutrophils. The primed state can be induced by neutrophil adhesion, pro-inflammatory cytokines, lipopolysaccharide, and other agents and has been characterized as a "ready to go" state, which results in a faster and higher response upon exposure to a second stimulus. The active state is found at the inflammatory or infection site. Activation is induced by the pathogen itself or by pathogen-derived formylated peptides and other agents. Finally, inactivation of NADPH oxidase is induced by anti-inflammatory agents to limit inflammation. Priming is a "double-edged sword" process as it contributes to a rapid and efficient elimination of the pathogens but can also induce the generation of large quantities of toxic ROS by hyperactivation of

  14. 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

  15. 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

  16. 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.

  17. Differences in activity of cytochrome C oxidase in brain between sleep and wakefulness.

    Science.gov (United States)

    Nikonova, Elena V; Vijayasarathy, Camasamudram; Zhang, Lin; Cater, Jacqueline R; Galante, Raymond J; Ward, Stephen E; Avadhani, Narayan G; Pack, Allan I

    2005-01-01

    Increased mRNA level of subunit 1 cytochrome c oxidase (COXI) during wakefulness and after short-term sleep deprivation has been described in brain. We hypothesized that this might contribute to increased activity of cytochrome oxidase (COX) enzyme during wakefulness, as part of the mechanisms to provide sufficient amounts of adenosine triphosphate to meet increased neuronal energy demands. COX activity was measured in isolated mitochondria from different brain regions in groups of rats with 3 hours of spontaneous sleep, 3 hours of spontaneous wake, and 3 hours of sleep deprivation. The group with 3 hours of spontaneous wake was added to delineate the circadian component of changes in the enzyme activity. Northern blot analysis was performed to examine the mRNA levels of 2 subunits of the enzyme COXI and COXIV, encoded by mitochondrial and nuclear DNA, respectively. Laboratory of Biochemistry, Department of Animal Biology, and Center for Sleep and Respiratory Neurobiology, University of Pennsylvania. 2-month-old male Fischer rats (N = 21) implanted for polygraphic recording. For COX activity, there was a main effect by analysis of variance of experimental group (P sleep-deprived groups as compared to the sleep group. A main effect of brain region was also significant (P sleep. There is an increase in COX activity after both 3 hours of spontaneous wake and 3 hours of sleep deprivation as compared with 3 hours of spontaneous sleep in diverse brain regions, which could be, in part, explained by the increased levels of bigenomic transcripts of the enzyme. This likely contributes to increased adenosine triphosphate production during wakefulness. ADP, adenosine diphosphate; ATP, adenosine triphosphate; COXI, cytochrome c oxidase subunit 1 mRNA; COX, cytochrome c oxidase (protein); CREB, cyclic AMP response element binding protein; DNA, deoxyribonucleic acid; EDTA, ethylenediaminetetraacetic acid; EEG, electroencephalography; EMG, electromyography; GABP, GA binding

  18. Sulfonation of vulcanized ethylene-propylene-diene terpolymer membranes

    International Nuclear Information System (INIS)

    Barroso-Bujans, F.; Verdejo, R.; Lozano, A.; Fierro, J.L.G.; Lopez-Manchado, M.A.

    2008-01-01

    In the present work, sulfonation of previously vulcanized ethylene propylene diene terpolymer (EPDM) membranes was developed in a swelling solvent with acetyl sulfate. This procedure avoids the need to pre-dissolve the raw polymer. The reaction conditions were optimized in terms of solvent type, reaction time, acetyl sulfate concentration and film thickness to obtain the maximum degree of sulfonation of the polymer. The sulfonation procedure presented in this study yields a degree of sulfonation comparable to the chlorosulfonic acid procedure. Sulfonic acid groups were detected by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, and quantified by titrations. Proton conductivity and water uptake were measured by means of impedance spectroscopy and swelling measurements, respectively, and were correlated with the degree of sulfonation. Tensile strength and Young's modulus of sulfonated EPDM increased with the degree of sulfonation, while elongation at break remained constant. Thermal stability of the sulfonated EPDM was studied by simultaneous thermogravimetry-mass spectroscopy

  19. Critical role of NADPH oxidase in neuronal oxidative damage and microglia activation following traumatic brain injury.

    Directory of Open Access Journals (Sweden)

    Quan-Guang Zhang

    Full Text Available BACKGROUND: Oxidative stress is known to play an important role in the pathology of traumatic brain injury. Mitochondria are thought to be the major source of the damaging reactive oxygen species (ROS following TBI. However, recent work has revealed that the membrane, via the enzyme NADPH oxidase can also generate the superoxide radical (O(2(-, and thereby potentially contribute to the oxidative stress following TBI. The current study thus addressed the potential role of NADPH oxidase in TBI. METHODOLOGY/PRINCIPAL FINDINGS: The results revealed that NADPH oxidase activity in the cerebral cortex and hippocampal CA1 region increases rapidly following controlled cortical impact in male mice, with an early peak at 1 h, followed by a secondary peak from 24-96 h after TBI. In situ localization using oxidized hydroethidine and the neuronal marker, NeuN, revealed that the O(2(- induction occurred in neurons at 1 h after TBI. Pre- or post-treatment with the NADPH oxidase inhibitor, apocynin markedly inhibited microglial activation and oxidative stress damage. Apocynin also attenuated TBI-induction of the Alzheimer's disease proteins β-amyloid and amyloid precursor protein. Finally, both pre- and post-treatment of apocynin was also shown to induce significant neuroprotection against TBI. In addition, a NOX2-specific inhibitor, gp91ds-tat was also shown to exert neuroprotection against TBI. CONCLUSIONS/SIGNIFICANCE: As a whole, the study demonstrates that NADPH oxidase activity and superoxide production exhibit a biphasic elevation in the hippocampus and cortex following TBI, which contributes significantly to the pathology of TBI via mediation of oxidative stress damage, microglial activation, and AD protein induction in the brain following TBI.

  20. 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...

  1. 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.

  2. Ag-doped CdO nanocatalysts: Preparation, characterization and catechol oxidase activity

    Science.gov (United States)

    El-Kemary, Maged; El-Mehasseb, Ibrahim; El-Shamy, Hany

    2018-06-01

    Silver doped cadmium oxide (Ag/CdO) nanoparticles with an average size of 41 nm have been successfully synthesized via thermal decomposition and liquid impregnation technique. The structural characterization has been performed by using several spectroscopic techniques, e.g., X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier-transform infrared (FT-IR). The catechol oxidase has been studied by UV-visible absorption spectroscopy and fourier-transform infrared as well as the mechanism has been assured by cyclic voltammetry and fluorescence spectroscopy. The results indicate that the oxidation does not occur in the presence of unsupported cadmium oxide particles by silver and in the same time, the catechol oxidase activity of silver doped CdO nanoparticles were improved by about three orders of magnitude than silver ions.

  3. Intermittent hypoxia-induced cognitive deficits are mediated by NADPH oxidase activity in a murine model of sleep apnea.

    Directory of Open Access Journals (Sweden)

    Deepti Nair

    Full Text Available In rodents, exposure to intermittent hypoxia (IH, a hallmark of obstructive sleep apnea (OSA, is associated with neurobehavioral impairments, increased apoptosis in the hippocampus and cortex, as well as increased oxidant stress and inflammation. Excessive NADPH oxidase activity may play a role in IH-induced CNS dysfunction.The effect of IH during light period on two forms of spatial learning in the water maze and well as markers of oxidative stress was assessed in mice lacking NADPH oxidase activity (gp91phox(_/Y and wild-type littermates. On a standard place training task, gp91phox(_/Y displayed normal learning, and were protected from the spatial learning deficits observed in wild-type littermates exposed to IH. Moreover, anxiety levels were increased in wild-type mice exposed to IH as compared to room air (RA controls, while no changes emerged in gp91phox(_/Y mice. Additionally, wild-type mice, but not gp91phox(_/Y mice had significantly elevated levels of NADPH oxidase expression and activity, as well as MDA and 8-OHDG in cortical and hippocampal lysates following IH exposures.The oxidative stress responses and neurobehavioral impairments induced by IH during sleep are mediated, at least in part, by excessive NADPH oxidase activity, and thus pharmacological agents targeting NADPH oxidase may provide a therapeutic strategy in sleep-disordered breathing.

  4. 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.)

  5. 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.).

  6. Cytokinin oxidase from Phaseolus vulgaris callus tissues. Enhanced in vitro activity of the enzyme in the presence of copper-imidazole complexes

    International Nuclear Information System (INIS)

    Chatfield, J.M.; Armstrong, D.J.

    1987-01-01

    The effects of metal ions on cytokinin oxidase activity extracted from callus tissues of Phaseolus vulgaris L. cv Great Northern have been examined using an assay based on the oxidation of N 6 -(Δ 2 -isopentenyl)-adenine-2,8- 3 H (i 6 Ade) to adenine (Ade). The addition of cupric ions to reaction mixtures containing imidazole buffer markedly enhanced cytokinin oxidase activity. In the presence of optimal concentrations of copper and imidazole, cytokinin oxidase activity was stimulated more than 20-fold. The effect was enzyme dependent, specific for copper, and observed only in the presence of imidazole. The substrate specificity of the copper-imidazole enhanced reaction, as judged by substrate competition tests, was the same as that observed in the absence of copper and imidazole. Similarly, in tests involving DEAE-cellulose chromatography, elution profiles of cytokinin oxidase activity determined using a copper-imidazole enhanced assay were identical to those obtained using an assay without copper and imidazole. On the basis of these results, the addition of copper and imidazole to reaction mixtures used to assay for cytokinin oxidase activity is judged to provide a reliable and specific assay of greatly enhanced sensitivity for the enzyme. The mechanism by which copper and imidazole enhance cytokinin oxidase activity is not certain, but the reaction catalyzed by the enzyme was not inhibited by anaerobic conditions when these reagents were present. This observation suggests that copper-imidazole complexes are substituting for oxygen in the reaction mechanism by which cytokinin oxidase effects cleavage of the N 6 -side chain of i 6 Ade

  7. Sorption of perfluorooctanoic acid, perfluorooctane sulfonate and perfluoroheptanoic acid on granular activated carbon.

    Science.gov (United States)

    Zhang, Di; Luo, Qi; Gao, Bin; Chiang, Sheau-Yun Dora; Woodward, David; Huang, Qingguo

    2016-02-01

    The sorption of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluoroheptanoic acid (PFHpA) on granular activated carbon (GAC) was characterized and compared to explore the underlying mechanisms. Sorption of the three perfluoroalkyl acids (PFAAs) on GAC appeared to be a rapid intra-particle diffusion process, which were well represented by the pseudo-second-order rate model with the sorption rate following the order PFOS > PFOA > PFHpA. Sorption isotherm data were well fitted by the Freundlich model with the sorption capacity (Kf) of PFOS, PFOA and PFHpA being 4.45, 2.42 and 1.66 respectively. This suggests that the hydrophilic head group on PFAAs, i.e. sulfonate vs carboxylic, has a strong influence on their sorption. Comparison between PFOA and PFHpA revealed that hydrophobicity could also play a role in the sorption of PFAAs on GAC when the fluorocarbon chain length is different. Analyses using Attenuated Total Reflection (ATR)-Fourier Transform Infrared (FTIR) spectroscopy suggested possible formation of a negative charge-assisted H-bond between PFAAs and the functionalities on GAC surfaces, including non-aromatic ketones, sulfides, and halogenated hydrocarbons. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Uptake and utilization of sulfonic acids in the cyanobacterial strains Anabaena variabilis and Plectonema 73110

    International Nuclear Information System (INIS)

    Biedlingmaier, S.; Schmidt, A.

    1987-01-01

    Growth of several cyanobacteria was examined on ethane sulfonate and taurine as only sulfur source. Comparing two strains with differential utilization of sulfonic acids (Anabaena variabilis and Synechococcus 6301) demonstrated that actual growth was coupled to the presence of an active sulfonate transport system due to species specific properties and nutritional conditions. Sulfonate uptake in Anabaena variabilis was characterized by a pH optimum of 6.5, a structural specificity for sulfonates, missing Na + dependence, and phosphate stimulation. Radiolabeled ethane sulfonate and taurine was metabolized to products of normal sulfur metabolism. Also considerable amounts of 35 S-labeled volatiles (mercaptanes and sulfide) could be detected, suggesting a degradation mechanism via reduction to mercaptanes and cleavage of the C-S bond. (orig.)

  9. Monoamine oxidase inhibitory activity in tobacco particulate matter: Are harman and norharman the only physiologically relevant inhibitors?

    Science.gov (United States)

    Truman, Penelope; Grounds, Peter; Brennan, Katharine A

    2017-03-01

    Monoamine oxidase inhibition is significant in smokers, but it is still unclear how the inhibition that is seen in the brains and bodies of smokers is brought about. Our aim was to test the contribution of the harman and norharman in tobacco smoke to MAO-A inhibition from tobacco smoke preparations, as part of a re-examination of harman and norharman as the cause of the inhibition of MAO-A inhibition in the brain. Tobacco smoke particulate matter and cigarette smoke particulate matter were prepared and the amounts of harman and norharman measured. The results were compared with the total monoamine oxidase-A inhibitory activity. At a nicotine concentration of 0.6μM (a "physiological" concentration in blood) the total monoamine oxidase-A inhibitory activity measured in these samples was sufficient to inhibit the enzyme by approximately 10%. Of this inhibitory activity, only a small proportion of the total was found to be due to harman and norharman. These results show that harman and norharman provide only a moderate contribution to the total monoamine oxidase-A inhibitory activity of tobacco smoke, perhaps under 10%. This suggests that other inhibitors (either known or unknown) may be more significant contributors to total inhibitory activity than has yet been established, and deserve closer examination. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Synthesis and Properties of Poly(ether sulfone)s with Clustered Sulfonic Groups for PEMFC Applications under Various Relative Humidity.

    Science.gov (United States)

    Lee, Shih-Wei; Chen, Jyh-Chien; Wu, Jin-An; Chen, Kuei-Hsien

    2017-03-22

    Novel sulfonated poly(ether sulfone) copolymers (S4PH-x-PSs) based on a new aromatic diol containing four phenyl substituents at the 2, 2', 6, and 6' positions of 4,4'-diphenyl ether were synthesized. Sulfonation was found to occur exclusively on the 4 position of phenyl substituents by NMR spectroscopy. The ion exchange capacity (IEC) values can be controlled by adjusting the mole percent (x in S4PH-x-PS) of the new diol. The fully hydrated sulfonated poly(ether sulfone) copolymers had good proton conductivity in the range 0.004-0.110 S/cm at room temperature. The surface morphology of S4PH-x-PSs and Nafion 212 was investigated by atomic force microscopy (tapping-mode) and related to the percolation limit and proton conductivity. Single H 2 /O 2 fuel cell based on S4PH-40-PS loaded with 0.25 mg/cm 2 catalyst (Pt/C) exhibited a peak power density of 462.6 mW/cm 2 , which was close to that of Nafion 212 (533.5 mW/cm 2 ) at 80 °C with 80% RH. Furthermore, fuel cell performance of S4PH-35-PS with various relative humidity was investigated. It was confirmed from polarization curves that the fuel cell performance of S4PH-35-PS was not as high as that of Nafion 212 under fully hydrated state due to higher interfacial resistance between S4PH-35-PS and electrodes. While under low relative humidity (53% RH) at 80 °C, fuel cells based on S4PH-35-PS showed higher peak power density (234.9 mW/cm 2 ) than that (214.0 mW/cm 2 ) of Nafion 212.

  11. Role of post-sulfonation of poly(ether ether sulfone) in proton conductivity and chemical stability of its proton exchange membranes for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Unveren, Elif Erdal; Erdogan, Tuba; Inan, Tulay Y. [Chemistry Institute, TUBITAK Marmara Research Center, 41470, Gebze, Kocaeli (Turkey); Celebi, Serdar S. [Professor Emeritus, Chemical Engineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey)

    2010-04-15

    Commercially available poly(ether ether sulfone), PEES, was directly sulfonated using concentrated sulfuric acid at low temperatures by minimizing degradation during sulfonation. The sulfonation reaction was performed in the temperature range of 5-25 C. Sulfonated polymers were characterized by FTIR, {sup 1}H NMR spectroscopy and ion exchange capacity (IEC) measurements. Degradation during sulfonation was investigated by measuring intrinsic viscosity, glass transition temperature and thermal decomposition temperature of sulfonated polymers. Sulfonated PEES, SPEES, membranes were prepared by solvent casting method and characterized in terms of IEC, proton conductivity and water uptake. The effect of sulfonation conditions on chemical stability of membranes was also investigated via Fenton test. Optimum sulfonation condition was determined to be 10 C with conc. H{sub 2}SO{sub 4} based on the characteristics of sulfonated polymers and also the chemical stability of their membranes. SPEES membranes exhibited proton conductivity up to 185.8 mS cm{sup -1} which is higher than that of Nafion 117 (133.3 mS cm{sup -1}) measured at 80 C and relative humidity 100%. (author)

  12. Sulfonated poly(ether ether ketone) membranes for electric double layer capacitors

    International Nuclear Information System (INIS)

    Kim, Wan Ju; Kim, Dong-Won

    2008-01-01

    Sulfonated poly(ether ether ketone) (S-PEEK) with different degree of sulfonation (DS) has been prepared and evaluated as a proton conducting membrane for electric double layer capacitor (EDLC). The polymer electrolytes prepared with S-PEEK membrane exhibited ionic conductivities about 1.2 x 10 -3 -4.5 x 10 -3 S cm -1 at room temperature, which depended on both soaking solvent and degree of sulfonation. The quasi-solid-state EDLCs consisted of activated carbon electrodes and S-PEEK membrane were assembled, and their electrochemical characteristics were studied by cyclic voltammetry and charge-discharge cycle tests. The effect of DS on the electrochemical performances of EDLCs has been investigated

  13. Sulfonated 1,3-bis(4-pyridylpropane

    Directory of Open Access Journals (Sweden)

    Ore Kuyinu

    2011-06-01

    Full Text Available In the title compound, 4-[3-(3-sulfonatopyridin-1-ium-4-ylpropyl]pyridin-1-ium-3-sulfonate, C13H14N2O6S2, the molecule is zwitterionic, with the sulfonic acid proton transfered to the basic pyridine N atom. Also, the structure adopts a butterfly-like conformation with the sulfonate groups on opposite sides of the `wings'. The dihedral angle between the two pyridinium rings is 83.56 (7°, and this results in the molecule having a chiral conformation and packing. There is strong intermolecular hydrogen bonding between the pyridinium H and sulfonate O atoms of adjoining molecules. In addition, there are weaker intermolecular C—H...O interactions.

  14. 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.

  15. Sildenafil promotes eNOS activation and inhibits NADPH oxidase in the transgenic sickle cell mouse penis.

    Science.gov (United States)

    Musicki, Biljana; Bivalacqua, Trinity J; Champion, Hunter C; Burnett, Arthur L

    2014-02-01

    Sickle cell disease (SCD)-associated vasculopathy in the penis is characterized by aberrant nitric oxide and phosphodiesterase (PDE) 5 signaling, and by increased oxidative stress. Preliminary clinical trials show that continuous treatment with PDE5 inhibitor sildenafil unassociated with sexual activity decreases priapic activity in patients with SCD. However, the mechanism of its vasculoprotective effect in the penis remains unclear. We evaluated whether continuous administration of PDE5 inhibitor sildenafil promotes eNOS function at posttranslational levels and decreases superoxide-producing enzyme NADPH oxidase activity in the sickle cell mouse penis. SCD transgenic mice were used as an animal model of SCD. WT mice served as controls. Mice received treatment with the PDE5 inhibitor sildenafil (100 mg/kg/day) or vehicle for 3 weeks. eNOS phosphorylation on Ser-1177 (positive regulatory site), eNOS interactions with heat-shock protein 90 (HSP90) (positive regulator), phosphorylated AKT (upstream mediator of eNOS phosphorylation on Ser-1177), an NADPH oxidase catalytic subunit gp91(phox), and a marker of oxidative stress (4-hydroxy-2-nonenal [HNE]) were measured by Western blot. Effect of continuous sildenafil treatment on eNOS posttranslational activation, NADPH oxidase catalytic subunit, and oxidative stress in the penis of the sickle cell mouse. Continuous treatment with sildenafil reversed (P penis. Sildenafil treatment of WT mice did not affect any of these parameters. Our findings that sildenafil enhances eNOS activation and inhibits NADPH oxidase function in the sickle cell mouse penis offers a vasculoprotective molecular basis for the therapeutic effect of sildenafil in the penis in association with SCD. © 2013 International Society for Sexual Medicine.

  16. 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

  17. 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.

  18. Preparation of a Carbon-Based Solid Acid Catalyst by Sulfonating Activated Carbon in a Chemical Reduction Process

    Directory of Open Access Journals (Sweden)

    Xiao-Yan Liu

    2010-10-01

    Full Text Available Sulfonated (SO3H-bearing activated carbon (AC-SO3H was synthesized by an aryl diazonium salt reduction process. The obtained material had a SO3H density of 0.64 mmol·g-1 and a specific surface area of 602 m2·g-1. The catalytic properties of AC-SO3H were compared with that of two commercial solid acid catalysts, Nafion NR50 and Amberlyst-15. In a 10-h esterification reaction of acetic acid with ethanol, the acid conversion with AC-SO3H (78% was lower than that of Amberlyst-15 (86%, which could be attributed to the fact that the SO3H density of the sulfonated carbon was lower than that of Amberlyst-15 (4.60 mmol·g-1. However, AC-SO3H exhibited comparable and even much higher catalytic activities than the commercial catalysts in the esterification of aliphatic acids with longer carbon chains such as hexanoic acid and decanoic acid, which may be due to the large specific surface area and mesoporous structures of the activated carbon. The disadvantage of AC-SO3H is the leaching of SO3H group during the reactions.

  19. 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.

  20. 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.

  1. A study of the effect of polystyrene sulfonation on the performance of terephthaloyl chloride-dihydroxydiphenyl sulfone copolymer/polystyrene system

    Science.gov (United States)

    Kahraman, R.; Kahn, K. A.; Ali, S. A.; Hamid, S. H.; Sahin, A. Z.

    1998-12-01

    Thermal, morphological, and mechanical properties of composites of a liquid crystalline copolymer (LCP) poly(terephthaloyl chloride)-co-(p,p’-dihydroxydiphenyl sulfone) with polystyrene (PS) and sulfonated polystyrene (SPS) are presented and discussed. Sulfonation of polystyrene was expected to improve the interfacial adhesion by introducing hydrogen bonding in the LCP/PS system. The degree of sulfonation was 11 %. The incompatibility (lack of proper interfacial adhesion) of the LCP/PS system resulted in sharp decrease in the composite tensile strength with LCP addition. The performance of the system did not change when processed at a higher temperature (270 °C instead of 225 °C). While a composite plate of 25% LCP/PS could not be fabricated, it was possible for LCP/SPS (processed at 215 °C), indicating some improvement in interfacial bonding by sulfonation. Sulfonation of PS resulted in fracture with some degree of plastic deformation for pure SPS matrix and also the LCP/SPS system with the lowest LCP content (1 wt%), whereas plastic deformation was not observed for PS used as received. The strength of the LCP/SPS system also decreased with increase in LCP content, indicating that 11% sulfonation is not sufficient to introduce significant compatibility, but it was not as dramatic as that for LCP/PS. The performance of the LCP/SPS system was not affected significantly by heat treatment at the process temperature.

  2. Sulfonated polyphenyl ether by electropolymerization

    International Nuclear Information System (INIS)

    Hou Hongying; Vacandio, Florence; Di Vona, Maria Luisa; Knauth, Philippe

    2012-01-01

    Highlights: ► Sulfonated polyphenyl ether was for the first time electropolymerized. ► This technique allows the economical preparation of ionomeric membranes for electrochemical energy technologies. ► The mechanism of electropolymerization was discussed in detail. - Abstract: Electropolymerization of sulfonated phenol was for the first time achieved and studied by cyclic voltammetry (CV) and chronoamperometry on stainless steel substrates. The obtained sulfonated polyphenyl ether was characterized in terms of impedance spectroscopy, nuclear magnetic resonance (NMR), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and Fourier-Transform Infrared (FTIR) spectroscopy. Dense films of micrometer thickness can be obtained; the proton conductivity is about 3 mS/cm at room temperature.

  3. Amperometric urea biosensors based on sulfonated graphene/polyaniline nanocomposite

    Directory of Open Access Journals (Sweden)

    Das G

    2015-08-01

    Full Text Available Gautam Das, Hyon Hee Yoon Department of Chemical and Biological Engineering, Gachon University, Seongnam, Gyeonggi-do, South Korea Abstract: An electrochemical biosensor based on sulfonated graphene/polyaniline nanocomposite was developed for urea analysis. Oxidative polymerization of aniline in the presence of sulfonated graphene oxide was carried out by electrochemical methods in an aqueous environment. The structural properties of the nanocomposite were characterized by Fourier-transform infrared, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. The urease enzyme-immobilized sulfonated graphene/polyaniline nanocomposite film showed impressive performance in the electroanalytical detection of urea with a detection limit of 0.050 mM and a sensitivity of 0.85 µA·cm-2·mM-1. The biosensor achieved a broad linear range of detection (0.12–12.3 mM with a notable response time of approximately 5 seconds. Moreover, the fabricated biosensor retained 81% of its initial activity (based on sensitivity after 15 days of storage at 4°C. The ease of fabrication coupled with the low cost and good electrochemical performance of this system holds potential for the development of solid-state biosensors for urea detection. Keywords: electrochemical deposition, sulfonated graphene oxide, urease

  4. Properties of polypyrrole doped with alkylbenzene sulfonates

    DEFF Research Database (Denmark)

    Bay, Lasse; Skaarup, Steen; West, Keld

    2001-01-01

    -standing 10 mu m thick film is prepared electrochemically at a constant current from an aqueous solution of pyrrole and sodium alkylbenzene sulfonate. The mechanical properties of the film (tensile strength and Young's modulus) and the reversible linear elongation between the oxidised and reduced states...... are measured. Alkylbenzene sulfonates with alkyl chain lengths between 1 and 22 carbon atoms are used as dopant anion. The films made with the different anions have highly different properties and are here compared to outline the influence of the size of the anion. A maximum in linear elongation is found for p......-(n-octyl)benzene sulfonate and in conductivity for p-(n-butyl)benzene sulfonate....

  5. Alkyl Substitution Effect on Oxidation Stability of Sulfone-Based Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Su, Chi-Cheung [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne IL 60439 USA; He, Meinan [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne IL 60439 USA; Redfern, Paul [Materials Science Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne IL 60439 USA; Curtiss, Larry A. [Materials Science Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne IL 60439 USA; Liao, Chen [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne IL 60439 USA; Zhang, Lu [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne IL 60439 USA; Burrell, Anthony K. [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne IL 60439 USA; Zhang, Zhengcheng [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne IL 60439 USA

    2016-02-16

    Organic sulfone compounds have been widely used as high-voltage electrolytes for lithium-ion batteries for decades. However, owing to the complexity of the synthesis of new sulfones, only a few commercially available sulfones have been studied. In this paper, we report the synthesis of new sulfone compounds with various substituent groups and the impact of the substituent group on the oxidation stability of sulfones. Electrochemical floating tests using a 5 V LiNi0.5Mn1.5O4 spinel cathode and density functional theory calculations showed that the cyclopentyl-substituted sulfone McPS suffered from oxidation instability, starting from 4.9 V versus Li+/Li, as observed by the large leakage currents. On the other hand, the isopropyl-substituted sulfone MiPS and tetramethylene substituted sulfone TMS showed much improved oxidation stability under identical testing conditions. The substitution structure of the sulfone plays a significant role in the determination of its oxidative stability and should first be considered for the development of new sulfone-based electrolytes for high-voltage, high-energy lithium-ion batteries.

  6. Sulfonated chitosan and dopamine based coatings for metallic implants in contact with blood.

    Science.gov (United States)

    Campelo, Clayton S; Chevallier, Pascale; Vaz, Juliana M; Vieira, Rodrigo S; Mantovani, Diego

    2017-03-01

    Thrombosis and calcification constitute the main clinical problems when blood-interacting devices are implanted in the body. Coatings with thin polymer layers represent an acknowledged strategy to modulate interactions between the material surface and the blood environment. To ensure the implant success, at short-term the coating should limit platelets adhesion and delay the clot formation, and at long-term it should delay the calcification process. Sulfonated chitosan, if compared to native chitosan, shows the unique ability to reduce proteins adsorption, decrease thrombogenic properties and limit calcification. In this work, stainless steel surfaces, commonly used for cardiovascular applications, were coated with sulfonated chitosan, by using dopamine and PEG as anchors, and the effect of these grafted surfaces on platelet adhesion, clot formation as well as on calcification were investigated. Surface characterization techniques evidenced that the coating formation was successful, and the sulfonated chitosan grafted sample exhibited a higher roughness and hydrophilicity, if compared to native chitosan one. Moreover, sulfonated surface limited platelet activation and the process of clot formation, thus confirming its high biological performances in blood. Calcium deposits were also lower on the sulfonated chitosan sample compared to the chitosan one, thus showing that calcification was minimal in presence of sulfonate groups. In conclusion, this sulfonated-modified surface has potential to be as blood-interacting material. Copyright © 2016. Published by Elsevier B.V.

  7. 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.

  8. 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.

  9. 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.

  10. Controlled sulfonation of poly(ether sulfone using phthalic anhydride as catalyst and its membrane performance for fuel cell application

    Directory of Open Access Journals (Sweden)

    Seikh Jiyaur Rahaman

    2016-09-01

    Full Text Available Proton exchange membrane (PEM fuel cells are one of the most emerging alternative energy technologies under development. A novel proton exchange membrane sulfonated polyethersulfone (SPES was developed by homogeneous method using phthalic anhydride as catalyst and chlorosulfonic acid as sulfonating agent to control the sulfonation reaction. The method of sulfonation was optimized by varying the reaction time and concentration of the catalyst. The structure of the SPES was studied by 1H-Nuclear Magnetic Resonance, Fourier Transform Infra Red Spectroscopy and X-ray diffraction. The extent of sulfonation was determined by ion exchange capacity studies. The thermal and mechanical stabilities were studied using thermogravimetric analysis (TGA and Dynamic Mechanical Analysis (DMA respectively. DMA results show that the storage modulus increased with increase in degree of sulfonation (DS and water uptake of SPES increased with DS. The proton conductivity of SPES (34% DS measured by impedance spectroscopy was found to be 0.03S/cm at 80%RH and 100°C. Also, current-voltage polarization characteristics of SPES membranes offer a favourable alternative PEM due to the thermal stability and cost effective than perfluorinated ionomers.

  11. 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.

  12. Electrochemical characterization of adsorbed bilirubin oxidase on Vulcan XC 72R for the biocathode preparation in a glucose/O2 biofuel cell

    International Nuclear Information System (INIS)

    Habrioux, A.; Napporn, T.; Servat, K.; Tingry, S.; Kokoh, K.B.

    2010-01-01

    A new biocathode was built and tested. It consisted of bilirubin oxidase adsorbed on Vulcan XC 72 R and immobilized into a Nafion matrix. The possibility of direct electron transfer between bilirubin oxidase and Vulcan XC 72 R was also demonstrated. The kinetics on biocathode were enhanced by including 2,2'-azinobis-3-ethylbenzothiazoline-5-sulfonic acid in the catalytic film. A first order reaction rate was observed for oxygen concentrations lower than 22%. A complete kinetic investigation of the system was shown. A biofuel cell test performed with this biocathode and Au 70 Pt 30 nanoparticles as anode catalyst permitted to reach a power density of 170 μW cm -2 at a cell voltage of 0.6 V, which is superior to what can be obtained with the concentric design.

  13. Characterization of three bioenergetically active respiratory terminal oxidases in the cyanobacterium Synechocystis sp. strain PCC 6803.

    Science.gov (United States)

    Pils, D; Schmetterer, G

    2001-09-25

    Synechocystis sp. PCC 6803 contains three respiratory terminal oxidases (RTOs): cytochrome c oxidase (Cox), quinol oxidase (Cyd), and alternate RTO (ARTO). Mutants lacking combinations of the RTOs were used to characterize these key enzymes of respiration. Pentachlorophenol and 2-heptyl-4-hydroxy-quinoline-N-oxide inhibited Cyd completely, but had little effect on electron transport to the other RTOs. KCN inhibited all three RTOs but the in vivo K(I) for Cox and Cyd was quite different (7 vs. 27 microM), as was their affinity for oxygen (K(M) 1.0 vs. 0.35 microM). ARTO has a very low respiratory activity. However, when uptake of 3-O-methylglucose, an active H+ co-transport, was used to monitor energization of the cytoplasmic membrane, ARTO was similarly effective as the other RTOs. As removal of the gene for cytochrome c(553) had the same effects as removal of ARTO genes, we propose that the ARTO might be a second Cox. The possible functions, localization and regulation of the RTOs are discussed.

  14. Nitric oxide production and monoamine oxidase activity in cancer patients during interferon-a therapy

    NARCIS (Netherlands)

    D. Fekkes (Durk); A.R. van Gool (Arthur); M. Bannink (Marjolein); S. Sleijfer (Stefan); W.H.J. Kruit (Wim); B. van der Holt (Bronno); A.M.M. Eggermont (Alexander); M.W. Hengeveld (Michiel); G. Stoter (Gerrit)

    2009-01-01

    textabstractAbstract Both increased and decreased nitric oxide (NO) synthesis have been reported in patients treated with interferon-alpha (IFN-alpha). Animal studies showed that IFN-alpha administration results in increased levels of biogenic amines, subsequent activation of monoamine oxidases

  15. Modification of Coal Char-loaded TiO2 by Sulfonation and Alkylsilylation to Enhance Catalytic Activity in Styrene Oxidation with Hydrogen Peroxide as Oxidant

    Directory of Open Access Journals (Sweden)

    Mukhamad Nurhadi

    2017-04-01

    Full Text Available The modified coal char from low-rank coal by sulfonation, titanium impregnation and followed by alkyl silylation possesses high catalytic activity in styrene oxidation. The surface of coal char was undergone several steps as such: modification using concentrated sulfuric acid in the sulfonation process, impregnation of 500 mmol titanium(IV isopropoxide and followed by alkyl silylation of n-octadecyltriclorosilane (OTS. The catalysts were characterized by X-ray diffraction (XRD, IR spectroscopy, nitrogen adsorption, and hydrophobicity. The catalytic activity of the catalysts has been examined in the liquid phase styrene oxidation by using aqueous hydrogen peroxide as oxidant. The catalytic study showed the alkyl silylation could enhance the catalytic activity of Ti-SO3H/CC-600(2.0. High catalytic activity and reusability of the o-Ti-SO3H/CC-600(2.0 were related to the modification of local environment of titanium active sites and the enhancement the hydrophobicity of catalyst particle by alkyl silylation. Copyright © 2017 BCREC GROUP. All rights reserved Received: 24th May 2016; Revised: 11st October 2016; Accepted: 18th October 2016 How to Cite: Nurhadi, M. (2017. Modification of Coal Char-loaded TiO2 by Sulfonation and Alkylsilylation to Enhance Catalytic Activity in Styrene Oxidation with Hydrogen Peroxide as Oxidant. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (1: 55-61 (doi:10.9767/bcrec.12.1.501.55-61 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.1.501.55-61

  16. Activation of endothelial cells after exposure to ambient ultrafine particles: The role of NADPH oxidase

    International Nuclear Information System (INIS)

    Mo Yiqun; Wan Rong; Chien Sufan; Tollerud, David J.; Zhang Qunwei

    2009-01-01

    Several studies have shown that ultrafine particles (UFPs) may pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant increase in lung epithelial permeability. The direct effects of UFPs on vascular endothelium remain unknown. We hypothesized that exposure to UFPs leads to endothelial cell O 2 ·- generation via NADPH oxidase and results in activation of endothelial cells. Our results showed that UFPs, at a non-toxic dose, induced reactive oxygen species (ROS) generation in mouse pulmonary microvascular endothelial cells (MPMVEC) that was inhibited by pre-treatment with the ROS scavengers or inhibitors, but not with the mitochondrial inhibitor, rotenone. UFP-induced ROS generation in MPMVEC was abolished by p67 phox siRNA transfection and UFPs did not cause ROS generation in MPMVEC isolated from gp91 phox knock-out mice. UFP-induced ROS generation in endothelial cells was also determined in vivo by using a perfused lung model with imaging. Moreover, Western blot and immunofluorescence staining results showed that MPMVEC treated with UFPs resulted in the translocation of cytosolic proteins of NADPH oxidase, p47 phox , p67 phox and rac 1, to the plasma membrane. These results demonstrate that NADPH oxidase in the pulmonary endothelium is involved in ROS generation following exposure to UFPs. To investigate the activation of endothelial cells by UFP-induced oxidative stress, we determined the activation of the mitogen-activated protein kinases (MAPKs) in MPMVEC. Our results showed that exposure of MPMVEC to UFPs caused increased phosphorylation of p38 and ERK1/2 MAPKs that was blocked by pre-treatment with DPI or p67 phox siRNA. Exposure of MPMVEC obtained from gp91 phox knock-out mice to UFPs did not cause increased phosphorylation of p38 and ERK1/2 MAPKs. These findings confirm that UFPs can cause endothelial cells to generate ROS directly via activation of NADPH oxidase. UFP-induced ROS lead to

  17. Evaluation of sulfonated carbon as catalyst in reactive distillation

    International Nuclear Information System (INIS)

    Orjuela, Alvaro; Civetta, Nicolas; Rivera, Jairo; Boyaca, Alejandro; Diaz, Jesus

    2004-01-01

    A packed bed using sulfonated coal catalytic pellets was prepared using a Colombian anthracitic coal. Such pellets were introduced in a semi batch distillation column to which acetic acid and ethanol were fed in order to determine experimentally the feasibility of obtaining ethyl acetate by reactive distillation operation. The carbonaceous catalytic packing was characterized by total exchange capacity, potentiometric titration and BET area. Experimental tests were carried out using three acid/alcohol ratios. Results of such process are shown by reaction conversion and concentration in distillate and bottom products. The sulfonated coal showed catalytic activity in this esterification reaction, with conversions between 29-45%

  18. 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)

  19. 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.

  20. Preferential inhibition of the plasma membrane NADH oxidase (NOX) activity by diphenyleneiodonium chloride with NADPH as donor

    Science.gov (United States)

    Morre, D. James

    2002-01-01

    The cell-surface NADH oxidase (NOX) protein of plant and animal cells will utilize both NADH and NADPH as reduced electron donors for activity. The two activities are distinguished by a differential inhibition by the redox inhibitor diphenyleneiodonium chloride (DPI). Using both plasma membranes and cells, activity with NADPH as donor was markedly inhibited by DPI at submicromolar concentrations, whereas with NADH as donor, DPI was much less effective or had no effect on the activity. The possibility of the inhibition being the result of two different enzymes was eliminated by the use of a recombinant NOX protein. The findings support the concept that NOX proteins serve as terminal oxidases for plasma membrane electron transport involving cytosolic reduced pyridine nucleotides as the natural electron donors and with molecular oxygen as the electron acceptor.

  1. Potential anticancer activity of curcumin analogs containing sulfone on human cancer cells

    Directory of Open Access Journals (Sweden)

    Zhang Qiuyan

    2016-01-01

    Full Text Available Three curcumin analogs(S1-S3 containing sulfone were investigated for their effects on human prostate cancer PC-3, colon cancer HT-29, lung cancer H1299 and pancreatic cancer BxPC-3 cells. The three compounds were approximately 16-to 96-fold more active than curcumin in these cell lines as determined by the MTT assay. The effects of these compounds on cell growth were further studied in prostate cancer PC-3 cells in both two dimensional (2D and three dimensional (3D cultures. S1-S3strongly inhibited the growth and induced cell death in PC-3 cells, and the effects of these compounds were associated with suppression of nuclear factor kappa B (NF-κB transcriptional activity. Moreover, treatment of PC-3 cells with all three compounds caused a decrease in the level of phosphorylated signal transducer and activator of transcription-3 (p-STAT3 (Tyr705,but not p-STAT3(Ser727. Only S1and S2decreased the presence of phosphorylated Akt (p-Akt in PC-3 cells. These curcumin analogs warrant further in vivo studies for anticancer activities in suitable animal models.

  2. Inhibition of acetylcholinesterase and cytochrome oxidase activity in Fasciola gigantica cercaria by phytoconstituents.

    Science.gov (United States)

    Sunita, Kumari; Habib, Maria; Kumar, P; Singh, Vinay Kumar; Husain, Syed Akhtar; Singh, D K

    2016-02-01

    Fasciolosis is an important cattle and human disease caused by Fasciola hepatica and Fasciola gigantica. One of the possible methods to control this problem is to interrupt the life cycle of Fasciola by killing its larva (redia and cercaria) in host snail. Molecular identification of cercaria larva of F. gigantica was done by comparing the nucleotide sequencing with adult F. gigantica. It was noted that nucleotide sequencing of cercaria larva and adult F. gigantica were 99% same. Every month during the year 2011-2012, in vivo treatment with 60% of 4 h LC50 of phyto cercaricides citral, ferulic acid, umbelliferone, azadirachtin and allicin caused significant inhibition of acetylcholinesterase (AChE) and cytochrome oxidase activity in the treated cercaria larva of F. gigantica. Whereas, activity of both enzymes were not significantly altered in the nervous tissues of vector snail Lymnaea acuminata exposed to same treatments. Maximum reduction in AChE (1.35% of control in month of June) and cytochrome oxidase (3.71% of control in the month of July) activity were noted in the cercaria exposed to 60% of 4 h LC50 of azadirachtin and allicin, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Inhibition of S-adenosylmethionine decarboxylase and diamine oxidase activities by analogues of methylglyoxal bis(guanylhydrazone) and their cellular uptake during lymphocyte activation.

    Science.gov (United States)

    Jänne, J; Morris, D R

    1984-03-15

    Several congeners of methylglyoxal bis(guanylhydrazone) were tested for their ability to inhibit eukaryotic putrescine-activated S-adenosylmethionine decarboxylase (EC 4.1.1.50) and intestinal diamine oxidase (EC 1.4.3.6). All the compounds tested, namely methylglyoxal bis(guanylhydrazone), ethylglyoxal bis(guanylhydrazone), dimethylglyoxal bis(guanylhydrazone) and the di-N"-methyl derivative of methylglyoxal bis(guanylhydrazone), were strong inhibitors of both yeast and mouse liver adenosylmethionine decarboxylase activity in vitro. The enzyme from both sources was most powerfully inhibited by ethylglyoxal bis(guanylhydrazone). All the diguanidines likewise inhibited diamine oxidase activity in vitro. The maximum intracellular concentrations of the ethyl and dimethylated analogues achieved in activated lymphocytes were only about one-fifth of that of the parent compound. However, both derivatives appeared to utilize the polyamine-carrier system, as indicated by competition experiments with spermidine.

  4. Pharmacokinetic profiles of perfluorobutane sulfonate and activation of hepatic genes in mice

    Science.gov (United States)

    Polyfluoroalkyl substances (PFAS) are organic chemicals with wide industrial and consumer uses. They are found ubiquitously at low levels in the environment and detectable in humans and wildlife. Perfluorobutane Sulfonate (PFBS) is a short-chained PFAS used to replace perfluorooc...

  5. Gamma radiation affects the anti-Leishmania activity of Bothrops moojeni venom and correlates with L-amino acid oxidase activity

    International Nuclear Information System (INIS)

    Tempone, A.G.; Lourenco, C.O.; Spencer, P.J.; Rogero, J.R.; Nascimento, N.; Andrade Junior, H.F.

    1999-01-01

    Leishmania causes human disfiguring skin disease in endemic areas of Amazon and North Eastern Brazil. Those parasites present a remarkable resistance to most treatments, except those using toxic antimonial salts. We detected a specific anti-Leishmania activity in snake venoms, using an in vitro promastigote assay. In this report, we analyzed the activity of Bothrops moojeni venom against L. Amazonensis, using whole venom or fractions of L-amino acid oxidase (L-AO). Crude venom of B.moojeni, was fractionated by molecular exclusion chromatography. Activity against promastigotes was detected by respiratory oxidative conversion of MTT in a colorimetric assay and L-AO activity was detected by a colorimetric assay with peroxidase and OPD as revealing reagents. Crude venom was irradiated with 500, 1000, and 2000 Gy in a 60 Co gamma radiation source. The venom had an anti-Leishmania activity of 33 pg/promastigote and the active fraction migrates as 100-150 kDa, close to the size described for L-AOs, and also presented L-AO activity. The radiation reduces both the L-AO and anti-Leishmania activity in a dose dependent effect. Those data suggests the anti-Leishmania activity in this venom is closely related to the L-amino acid oxidase activity and also that radiation could be used as a tool to detect specific activities reduction in water solutions, similarly to observed in dry preparations. (author)

  6. Treating shale oil to obtain sulfonates

    Energy Technology Data Exchange (ETDEWEB)

    Schaeffer, H

    1921-01-21

    The process shows as its principal characteristics: (1) treating the oil with chlorsulfonic acid at a temperature of about 100/sup 0/C; (2) the transformation of the sulfonic acid obtained into salts; (3) as new industrial products, the sulfonates obtained and their industrial application as disinfectants for hides and wood.

  7. 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 ...

  8. 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.

  9. Evaluation of genotoxic activity of maleic hydrazide, ethyl methane sulfonate, and N-nitroso diethylamine in Tradescantia

    OpenAIRE

    Alvarez-Moya Carlos; Santerre-Lucas Anne; Zúñiga-González Guillermo; Torres-Bugarín Olivia; Padilla-Camberos Eduardo; Feria-Velasco Alfredo

    2001-01-01

    Objective. To assess the genotoxic activity of N-nitroso diethylamine (NDEA), maleic hydrazide (MH), and ethyl methane sulfonate (EMS) using two systems: the comet assay on nuclei from Tradescantia, and the pink mutation test on Tradescantia staminal hairs (clone 4430). Material and Methods. Tradescantia cups was obtained from Laboratorio de Citogenética y Mutagénesis del Centro de Ciencias de la Atmósfera de la Universidad Nacional Autónoma de México and treated with: N-nitroso diethylamine ...

  10. Stability of glucose oxidase and catalase adsorbed on variously activated 13X zeolite.

    Science.gov (United States)

    Pifferi, P G; Vaccari, A; Ricci, G; Poli, G; Ruggeri, O

    1982-10-01

    The use of 13X zeolite (0.1-0.4-mm granules), treated with 2N and 0.01N HCI, 0.01M citric acid, 0.1M citric-phosphate buffer (pH 3.6), and in untreated form to adsorb glucose oxidase of fungal origin and microbial catalase was examined. Physicochemical analysis of the support demonstrated that its crystalline structure, greatly altered by the HCl and buffer, could be partially maintained with citric acid. The specific adsorption of the enzymes increased with decreasing pH and proved to be considerable for all the supports. The stability with storage at 25 degrees C is strictly correlated with the titrable acidity of the activated zeolite expressed as meq NaOH/g and with pH value of the activation solution. It proved to be lower than 55 h for both enzymes if adsorbed on zeolite treated with 2N HCl, and 15-fold and 30-fold higher for glucose oxidase and catalase adsorbed, respectively, on zeolite treated with the 0.1M citric-phosphate buffer and 0.01M citric acid. The specific adsorption of glucose oxidase and catalase was, respectively, 1840 U/g at pH 3.0 and 6910 U/g at pH 5.0. Their half-life at 25 degrees C with storage at pH 3.5 for the former and at pH 5.0 for the latter was 800 and 1560 h vs. 40 and 110 h for the corresponding free enzymes.

  11. Enhanced adsorption of perfluorooctane sulfonate and perfluorooctanoate by bamboo-derived granular activated carbon.

    Science.gov (United States)

    Deng, Shubo; Nie, Yao; Du, Ziwen; Huang, Qian; Meng, Pingping; Wang, Bin; Huang, Jun; Yu, Gang

    2015-01-23

    A bamboo-derived granular activated carbon with large pores was successfully prepared by KOH activation, and used to remove perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from aqueous solution. The granular activated carbon prepared at the KOH/C mass ratio of 4 and activation temperature of 900°C had fast and high adsorption for PFOS and PFOA. Their adsorption equilibrium was achieved within 24h, which was attributed to their fast diffusion in the micron-sized pores of activated carbon. This granular activated carbon exhibited the maximum adsorbed amount of 2.32mmol/g for PFOS and 1.15mmol/g for PFOA at pH 5.0, much higher than other granular and powdered activated carbons reported. The activated carbon prepared under the severe activation condition contained many enlarged pores, favorable for the adsorption of PFOS and PFOA. In addition, the spent activated carbon was hardly regenerated in NaOH/NaCl solution, while the regeneration efficiency was significantly enhanced in hot water and methanol/ethanol solution, indicating that hydrophobic interaction was mainly responsible for the adsorption. The regeneration percent was up to 98% using 50% ethanol solution at 45°C. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Andrographolide sulfonate ameliorates lipopolysaccharide-induced acute lung injury in mice by down-regulating MAPK and NF-κB pathways.

    Science.gov (United States)

    Peng, Shuang; Hang, Nan; Liu, Wen; Guo, Wenjie; Jiang, Chunhong; Yang, Xiaoling; Xu, Qiang; Sun, Yang

    2016-05-01

    Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is a severe, life-threatening medical condition characterized by widespread inflammation in the lungs, and is a significant source of morbidity and mortality in the patient population. New therapies for the treatment of ALI are desperately needed. In the present study, we examined the effect of andrographolide sulfonate, a water-soluble form of andrographolide (trade name: Xi-Yan-Ping Injection), on lipopolysaccharide (LPS)-induced ALI and inflammation. Andrographolide sulfonate was administered by intraperitoneal injection to mice with LPS-induced ALI. LPS-induced airway inflammatory cell recruitment and lung histological alterations were significantly ameliorated by andrographolide sulfonate. Protein levels of pro-inflammatory cytokines in bronchoalveolar lavage fluid (BALF) and serum were reduced by andrographolide sulfonate administration. mRNA levels of pro-inflammatory cytokines in lung tissue were also suppressed. Moreover, andrographolide sulfonate markedly suppressed the activation of mitogen-activated protein kinase (MAPK) as well as p65 subunit of nuclear factor-κB (NF-κB). In summary, these results suggest that andrographolide sulfonate ameliorated LPS-induced ALI in mice by inhibiting NF-κB and MAPK-mediated inflammatory responses. Our study shows that water-soluble andrographolide sulfonate may represent a new therapeutic approach for treating inflammatory lung disorders.

  13. Andrographolide sulfonate ameliorates lipopolysaccharide-induced acute lung injury in mice by down-regulating MAPK and NF-κB pathways

    Directory of Open Access Journals (Sweden)

    Shuang Peng

    2016-05-01

    Full Text Available Acute lung injury (ALI or acute respiratory distress syndrome (ARDS is a severe, life-threatening medical condition characterized by widespread inflammation in the lungs, and is a significant source of morbidity and mortality in the patient population. New therapies for the treatment of ALI are desperately needed. In the present study, we examined the effect of andrographolide sulfonate, a water-soluble form of andrographolide (trade name: Xi-Yan-Ping Injection, on lipopolysaccharide (LPS-induced ALI and inflammation. Andrographolide sulfonate was administered by intraperitoneal injection to mice with LPS-induced ALI. LPS-induced airway inflammatory cell recruitment and lung histological alterations were significantly ameliorated by andrographolide sulfonate. Protein levels of pro-inflammatory cytokines in bronchoalveolar lavage fluid (BALF and serum were reduced by andrographolide sulfonate administration. mRNA levels of pro-inflammatory cytokines in lung tissue were also suppressed. Moreover, andrographolide sulfonate markedly suppressed the activation of mitogen-activated protein kinase (MAPK as well as p65 subunit of nuclear factor-κB (NF-κB. In summary, these results suggest that andrographolide sulfonate ameliorated LPS-induced ALI in mice by inhibiting NF-κB and MAPK-mediated inflammatory responses. Our study shows that water-soluble andrographolide sulfonate may represent a new therapeutic approach for treating inflammatory lung disorders.

  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. Ultrasonic irradiation to modify the functionalized bionanocomposite in sulfonated polybenzimidazole membrane for fuel cells applications and antibacterial activity.

    Science.gov (United States)

    Esmaeilzade, Banafshe; Esmaielzadeh, Sheida; Ahmadizadegan, Hashem

    2018-04-01

    In this article the new proton exchange membranes were prepared from sulfonated polybenzimidazole (s-PBI) and various amounts of sulfonated titania/cellulose nanohybrids (titania/cellulose-SO 3 H) via ultrasonic waves. The ultrasonic irradiation effectively changes the rheology and the glass transition temperature and the crystallinity of the composite polymer. Ultrasonic irradiation has a very strong mixing and dispersion effect, much stronger than conventional stirring, which can improve the dispersion of titania/cellulose-SO 3 H nanoparticles in the polymer matrix. The strong -SO 3 H/-SO 3 H interaction between s-PBI chains and titania/cellulose-SO 3 H hybrids leads to ionic cross-linking in the membrane structure, which increases both the thermal stability and methanol resistance of the membranes. After acid doping with phosphoric acid, s-PBI/titania/cellulose-SO 3 H nanocomposite membranes exhibit depressions on methanol permeability and enhancements on proton conductivity comparing to the pristine s-PBI membrane. The chemical structure of the functionlized titania was characterized with FTIR, and energy-dispersive X-ray. Imidazole and sulfonated groups on the surface of modified nanoparticles forming linkages with s-PBI chains, improved the compatibility between s-PBI and nanoparticles, and enhanced the mechanical strength of the prepared nanocomposite membranes. From SEM and TEM analysis could explain the homogeneous dispersion of titania/cellulose-SO 3 H in nanocomposite membranes. Moreover, the membranes exhibited excellent antibacterial activities against S. aureus and E. coli. A. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. 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...

  17. Particle size effects of sulfonated graphene supported Pt nanoparticles on ethanol electrooxidation

    International Nuclear Information System (INIS)

    Sun, Chia-Liang; Tang, Jui-Shiang; Brazeau, Nicolas; Wu, Jhing-Jhou; Ntais, Spyridon; Yin, Chung-Wei; Chou, Hung-Lung; Baranova, Elena A.

    2015-01-01

    Highlights: • Pt colloidal nanoparticles with five mean diameters are synthesized. • Size-selected Pt nanoparticles are loaded on sulfonated graphene (sG). • Sulfonic acid functional groups atop graphene donate charge to Pt. • Pt-sG catalysts are used for ethanol oxidation reaction (EOR). • Pt-sG(2.5 nm) has the highest peak current density in EOR. - Abstract: Fuel cells are promising alternative in automobile and stationary power generation. Direct ethanol fuel cells (DEFCs) offer significant advantages due to the non-toxicity and renewability of ethanol as well as its high power density. Development of the efficient catalysts for ethanol oxidation reaction (EOR) has attracted great attention and represents one of the major challenges in electrocatalysis. Graphene, one-atom thick nanocarbon materials, has attracted much attention recently in a variety of applications. The sulfonation of graphene is able to make it hydrophilic, which enhances its dispersibility in aqueous solvents. Furthermore, sulfonation increases the adsorption and uniform distribution of the Pt nanoparticles, which increases both the electrocatalytic activity and the durability. In this study, theoretical calculations demonstrated that the sulfonate functional group can donate charge to Pt, enhanced the adsorption energy of Pt, and then reduce the adsorption energy of CO on Pt. Then experimentally five kinds of Pt/sulfonated-graphene (Pt/sG) catalysts were synthesized via the control of pH values during the preparation of five-selected colloidal nanoparticles. Among all catalysts, Pt-sG(2.5 nm) has the highest peak current density in EOR

  18. 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.

  19. Gamma radiation affects the anti-Leishmania activity of Bothrops moojeni venom and correlates with L-amino acid oxidase activity

    Energy Technology Data Exchange (ETDEWEB)

    Tempone, A.G.; Lourenco, C.O.; Spencer, P.J.; Rogero, J.R.; Nascimento, N. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Div. de Radiobiologia; Andrade Junior, H.F. [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina. Inst. de Medicina Tropical

    1999-11-01

    Leishmania causes human disfiguring skin disease in endemic areas of Amazon and North Eastern Brazil. Those parasites present a remarkable resistance to most treatments, except those using toxic antimonial salts. We detected a specific anti-Leishmania activity in snake venoms, using an in vitro promastigote assay. In this report, we analyzed the activity of Bothrops moojeni venom against L. Amazonensis, using whole venom or fractions of L-amino acid oxidase (L-AO). Crude venom of B.moojeni, was fractionated by molecular exclusion chromatography. Activity against promastigotes was detected by respiratory oxidative conversion of MTT in a colorimetric assay and L-AO activity was detected by a colorimetric assay with peroxidase and OPD as revealing reagents. Crude venom was irradiated with 500, 1000, and 2000 Gy in a {sup 60} Co gamma radiation source. The venom had an anti-Leishmania activity of 33 pg/promastigote and the active fraction migrates as 100-150 kDa, close to the size described for L-AOs, and also presented L-AO activity. The radiation reduces both the L-AO and anti-Leishmania activity in a dose dependent effect. Those data suggests the anti-Leishmania activity in this venom is closely related to the L-amino acid oxidase activity and also that radiation could be used as a tool to detect specific activities reduction in water solutions, similarly to observed in dry preparations. (author) 13 refs., 3 figs.

  20. Immobilization of cholesterol oxidase in LbL films and detection of cholesterol using ac measurements

    International Nuclear Information System (INIS)

    Moraes, Marli L.; Souza, Nara C. de; Hayasaka, Caio O.; Ferreira, Marystela; Rodrigues Filho, Ubirajara P.; Riul, Antonio; Zucolotto, Valtencir; Oliveira, Osvaldo N.

    2009-01-01

    The preserved activity of immobilized biomolecules in layer-by-layer (LbL) films can be exploited in various applications, including biosensing. In this study, cholesterol oxidase (COX) layers were alternated with layers of poly(allylamine hydrochloride) (PAH) in LbL films whose morphology was investigated with atomic force microscopy (AFM). The adsorption kinetics of COX layers comprised two regimes, a fast, first-order kinetics process followed by a slow process fitted with a Johnson-Mehl-Avrami (JMA) function, with exponent ∼ 2 characteristic of aggregates growing as disks. The concept based on the use of sensor arrays to increase sensitivity, widely employed in electronic tongues, was extended to biosensing with impedance spectroscopy measurements. Using three sensing units, made of LbL films of PAH/COX and PAH/PVS (polyvinyl sulfonic acid) and a bare gold interdigitated electrode, we were able to detect cholesterol in aqueous solutions down to the 10 -6 M level. This high sensitivity is attributed to the molecular-recognition interaction between COX and cholesterol, and opens the way for clinical tests to be made with low cost, fast experimental procedures

  1. 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

  2. Synthesis in pilot plant scale and physical properties of sulfonated polystyrene

    Directory of Open Access Journals (Sweden)

    Martins Cristiane R.

    2003-01-01

    Full Text Available The homogenous sulfonation of polystyrene was developed in a pilot plant scale producing polymers with different sulfonation degrees (18 to 22 mole % of sulfonated styrene units. The reaction yield depends chiefly on the concentration ratio of acetyl sulfate and polystyrene. The morphological and thermal properties of the sulfonated polystyrene obtained by homogeneous sulfonation were studied by means of scanning electron microscopy, differential scanning calorimetry and thermogravimetry. The glass transition temperature of sulfonated polystyrene increases in relation to pure polystyrene and DCp was evaluated in order to confirm the strong interactions among the ~SO3H groups.

  3. 21 CFR 173.395 - Trifluoromethane sulfonic acid.

    Science.gov (United States)

    2010-04-01

    ...) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Specific Usage Additives § 173.395 Trifluoromethane sulfonic acid. Trifluoromethane sulfonic acid... acid) may safely be used in the production of cocoa butter substitute from palm oil (1-palmitoyl-2...

  4. Kaempferol modulates pro-inflammatory NF-κB activation by suppressing advanced glycation endproducts-induced NADPH oxidase

    Science.gov (United States)

    Kim, Ji Min; Lee, Eun Kyeong; Kim, Dae Hyun; Yu, Byung Pal

    2010-01-01

    Advanced glycation endproducts (AGE) are oxidative products formed from the reaction between carbohydrates and a free amino group of proteins that are provoked by reactive species (RS). It is also known that AGE enhance the generation of RS and that the binding of AGE to a specific AGE receptor (RAGE) induces the activation of the redox-sensitive, pro-inflammatory transcription factor, nuclear factor-kappa B (NF-ĸB). In this current study, we investigated the anti-oxidative effects of short-term kaempferol supplementation on the age-related formation of AGE and the binding activity of RAGE in aged rat kidney. We further investigated the suppressive action of kaempferol against AGE's ability to stimulate activation of pro-inflammatory NF-ĸB and its molecular mechanisms. For this study, we utilized young (6 months old), old (24 months old), and kaempferol-fed (2 and 4 mg/kg/day for 10 days) old rats. In addition, for the molecular work, the rat endothelial cell line, YPEN-1 was used. The results show that AGE and RAGE were increased during aging and that these increases were blunted by kaempferol. In addition, dietary kaempferol reduced age-related increases in NF-κB activity and NF-ĸB-dependant pro-inflammatory gene activity. The most significant new finding from this study is that kaempferol supplementation prevented age-related NF-κB activation by suppressing AGE-induced nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase). Taken together, our results demonstrated that dietary kaempferol exerts its anti-oxidative and anti-inflammatory actions by modulating the age-related NF-κB signaling cascade and its pro-inflammatory genes by suppressing AGE-induced NADPH oxidase activation. Based on these data, dietary kaempferol is proposed as a possible anti-AGE agent that may have the potential for use in anti-inflammation therapies. PMID:20431987

  5. 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

  6. Multiblock copolymers with highly sulfonated blocks containing di- and tetrasulfonated arylene sulfone segments for proton exchange membrane fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Takamuku, Shogo; Jannasch, Patric [Polymer and Materials Chemistry, Department of Chemistry, Lund University (Sweden)

    2012-01-15

    Multiblock copoly(arylene ether sulfone)s with different block lengths and ionic contents are tailored for durable and proton-conducting electrolyte membranes. Two series of fully aromatic copolymers are prepared by coupling reactions between non-sulfonated hydrophobic precursor blocks and highly sulfonated hydrophilic precursor blocks containing either fully disulfonated diarylsulfone or fully tetrasulfonated tetraaryldisulfone segments. The sulfonic acid groups are exclusively introduced in ortho positions to the sulfone bridges to impede desulfonation reactions and give the blocks ion exchange capacities (IECs) of 4.1 and 4.6 meq. g{sup -1}, respectively. Solvent cast block copolymer membranes show well-connected hydrophilic nanophase domains for proton transport and high decomposition temperatures above 310 C under air. Despite higher IEC values, membranes containing tetrasulfonated tetraaryldisulfone segments display a markedly lower water uptake than the corresponding ones with disulfonated diarylsulfone segments when immersed in water at 100 C, presumably because of the much higher chain stiffness and glass transition temperature of the former segments. The former membranes have proton conductivities in level of a perfluorosulfonic acid membrane (NRE212) under fully humidified conditions. A membrane with an IEC of 1.83 meq. g{sup -1} reaches above 6 mS cm{sup -1} under 30% relative humidity at 80 C, to be compared with 10 mS cm{sup -1} for NRE212 under the same conditions. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Biofilm behavior on sulfonated poly(ether-ether-ketone) (sPEEK)

    Energy Technology Data Exchange (ETDEWEB)

    Montero, Juan F.D. [Center for Research on Dental Implants (CEPID), School of Dentistry (ODT), Federal University of Santa Catarina - UFSC, Florianópolis, SC 88040-900 (Brazil); Tajiri, Henrique A.; Barra, Guilherme M.O.; Fredel, Márcio C. [Department of Mechanical Engineering (EMC), Federal University of Santa Catarina (UFSC), Florianópolis, SC 88040-900 (Brazil); Benfatti, Cesar A.M.; Magini, Ricardo S. [Center for Research on Dental Implants (CEPID), School of Dentistry (ODT), Federal University of Santa Catarina - UFSC, Florianópolis, SC 88040-900 (Brazil); Pimenta, Andréa L. [Integrated Laboratories Technologies (InteLAB), Dept. Chemical Engineering (EQA), Federal University of Santa Catarina - UFSC, Florianópolis, SC 88040-970 (Brazil); Department of Biologie, Université de Cergy Pontoise, 2, Av. Adolphe Chauvin, 95302 Cergy Pontoise (France); Souza, Júlio C.M., E-mail: julio.c.m.souza@ufsc.br [Center for Research on Dental Implants (CEPID), School of Dentistry (ODT), Federal University of Santa Catarina - UFSC, Florianópolis, SC 88040-900 (Brazil); Center for Microelectromechanical Systems (CMEMS), Dept. Mechanical Engineering (DEM), Campus Azurém, 4800-058 Guimarães (Portugal)

    2017-01-01

    Poly(ether-ether-ketone) (PEEK) has also shown to be very attractive for incorporating therapeutic compounds thanks to a sulfonation process which modifies the material structure resulting in a sulfonated-PEEK (sPEEK). Concerning biomedical applications, the objective of this work was to evaluate the influence of different sulfonation degree of sPEEK on the biofilm growth. PEEK samples were functionalized by using sulphuric acid (98%) and then dissolved into dimethyl-sulfoxide. A dip coating technique was used to synthesize sPEEK thin films. The sulfonation degree of the materials was analyzed by FT-IR, H NMR, TG and IEC. The surfaces were characterized by scanning electron microscopy, profilometry and contact angle analyses. Subsequently, the biofilm formation on sulfonated-PEEK based on Streptococcus mutans and Enterococcus faecalis was measured by spectrophotometry, colony forming units (CFU mL{sup −1}) and SEM. Results obtained from thermal and chemical analyses showed an intensification in sulfonation degree for sPEEK at 2 and 2.5 h. The E. faecalis or S. mutans biofilm growth revealed statistically significant differences (p < 0.05) between 2 and 3 h sulfonation groups. A significant decrease (p < 0.05) in CFU mL{sup −1} was recorded for S. mutans or E. faecalis biofilm grown on 2.5 or 3 h sPEEK. Regarding the thermal-chemical and microbiologic analyses, the sulfonation degree of sPEEK ranging from 2 up to 3 h was successful capable to decrease the biofilm growth. That revealed an alternative strategy to embed anti-biofilm and therapeutic compounds into PEEK avoiding infections in biomedical applications. - Highlights: • PEEK can be dissolved to incorporate therapeutic compounds. • High sulfonation degree on sPEEK affected the biofilm growth. • The sulfonation degree must be controlled to maintain the properties of sPEEK.

  8. Biofilm behavior on sulfonated poly(ether-ether-ketone) (sPEEK)

    International Nuclear Information System (INIS)

    Montero, Juan F.D.; Tajiri, Henrique A.; Barra, Guilherme M.O.; Fredel, Márcio C.; Benfatti, Cesar A.M.; Magini, Ricardo S.; Pimenta, Andréa L.; Souza, Júlio C.M.

    2017-01-01

    Poly(ether-ether-ketone) (PEEK) has also shown to be very attractive for incorporating therapeutic compounds thanks to a sulfonation process which modifies the material structure resulting in a sulfonated-PEEK (sPEEK). Concerning biomedical applications, the objective of this work was to evaluate the influence of different sulfonation degree of sPEEK on the biofilm growth. PEEK samples were functionalized by using sulphuric acid (98%) and then dissolved into dimethyl-sulfoxide. A dip coating technique was used to synthesize sPEEK thin films. The sulfonation degree of the materials was analyzed by FT-IR, H NMR, TG and IEC. The surfaces were characterized by scanning electron microscopy, profilometry and contact angle analyses. Subsequently, the biofilm formation on sulfonated-PEEK based on Streptococcus mutans and Enterococcus faecalis was measured by spectrophotometry, colony forming units (CFU mL −1 ) and SEM. Results obtained from thermal and chemical analyses showed an intensification in sulfonation degree for sPEEK at 2 and 2.5 h. The E. faecalis or S. mutans biofilm growth revealed statistically significant differences (p < 0.05) between 2 and 3 h sulfonation groups. A significant decrease (p < 0.05) in CFU mL −1 was recorded for S. mutans or E. faecalis biofilm grown on 2.5 or 3 h sPEEK. Regarding the thermal-chemical and microbiologic analyses, the sulfonation degree of sPEEK ranging from 2 up to 3 h was successful capable to decrease the biofilm growth. That revealed an alternative strategy to embed anti-biofilm and therapeutic compounds into PEEK avoiding infections in biomedical applications. - Highlights: • PEEK can be dissolved to incorporate therapeutic compounds. • High sulfonation degree on sPEEK affected the biofilm growth. • The sulfonation degree must be controlled to maintain the properties of sPEEK.

  9. Activation of Recombinantly Expressed l-Amino Acid Oxidase from Rhizoctonia solani by Sodium Dodecyl Sulfate

    Directory of Open Access Journals (Sweden)

    Katharina Hahn

    2017-12-01

    Full Text Available l-Amino acid oxidases (l-AAO catalyze the oxidative deamination of l-amino acids to the corresponding α-keto acids. The non-covalently bound cofactor FAD is reoxidized by oxygen under formation of hydrogen peroxide. We expressed an active l-AAO from the fungus Rhizoctonia solani as a fusion protein in E. coli. Treatment with small amounts of the detergent sodium dodecyl sulfate (SDS stimulated the activity of the enzyme strongly. Here, we investigated whether other detergents and amphiphilic molecules activate 9His-rsLAAO1. We found that 9His-rsLAAO1 was also activated by sodium tetradecyl sulfate. Other detergents and fatty acids were not effective. Moreover, effects of SDS on the oligomerization state and the protein structure were analyzed. Native and SDS-activated 9His-rsLAAO1 behaved as dimers by size-exclusion chromatography. SDS treatment induced an increase in hydrodynamic radius as observed by size-exclusion chromatography and dynamic light scattering. The activated enzyme showed accelerated thermal inactivation and an exposure of additional protease sites. Changes in tryptophan fluorescence point to a more hydrophilic environment. Moreover, FAD fluorescence increased and a lower concentration of sulfites was sufficient to form adducts with FAD. Taken together, these data point towards a more open conformation of SDS-activated l-amino acid oxidase facilitating access to the active site.

  10. Exogenous thyroid hormones regulate the activity of citrate synthase and cytochrome c oxidase in warm- but not cold-acclimated lake whitefish (Coregonus clupeaformis)

    Science.gov (United States)

    Zak, Megan A.; Regish, Amy M.; McCormick, Stephen; Manzon, Richard G.

    2017-01-01

    Thermal acclimation is known to elicit metabolic adjustments in ectotherms, but the cellular mechanisms and endocrine control of these shifts have not been fully elucidated. Here we examined the relationship between thermal acclimation, thyroid hormones and oxidative metabolism in juvenile lake whitefish. Impacts of thermal acclimation above (19 °C) or below (8 °C) the thermal optimum (13 °C) and exposure to exogenous thyroid hormone (60 µg T4/g body weight) were assessed by quantifying citrate synthase and cytochrome c oxidase activities in liver, red muscle, white muscle and heart. Warm acclimation decreased citrate synthase activity in liver and elevated both citrate synthase and cytochrome c oxidase activities in red muscle. In contrast, induction of hyperthyroidism in warm-acclimated fish stimulated a significant increase in liver citrate synthase and heart cytochrome c oxidase activities, and a decrease in the activity of both enzymes in red muscle. No change in citrate synthase or cytochrome c oxidase activities was observed following cold acclimation in either the presence or absence of exogenous thyroid hormones. Collectively, our results indicate that thyroid hormones influence the activity of oxidative enzymes more strongly in warm-acclimated than in cold-acclimated lake whitefish, and they may play a role in mediating metabolic adjustments observed during thermal acclimation.

  11. Exogenous thyroid hormones regulate the activity of citrate synthase and cytochrome c oxidase in warm- but not cold-acclimated lake whitefish (Coregonus clupeaformis).

    Science.gov (United States)

    Zak, Megan A; Regish, Amy M; McCormick, Stephen D; Manzon, Richard G

    2017-06-01

    Thermal acclimation is known to elicit metabolic adjustments in ectotherms, but the cellular mechanisms and endocrine control of these shifts have not been fully elucidated. Here we examined the relationship between thermal acclimation, thyroid hormones and oxidative metabolism in juvenile lake whitefish. Impacts of thermal acclimation above (19°C) or below (8°C) the thermal optimum (13°C) and exposure to exogenous thyroid hormone (60µg T 4 /g body weight) were assessed by quantifying citrate synthase and cytochrome c oxidase activities in liver, red muscle, white muscle and heart. Warm acclimation decreased citrate synthase activity in liver and elevated both citrate synthase and cytochrome c oxidase activities in red muscle. In contrast, induction of hyperthyroidism in warm-acclimated fish stimulated a significant increase in liver citrate synthase and heart cytochrome c oxidase activities, and a decrease in the activity of both enzymes in red muscle. No change in citrate synthase or cytochrome c oxidase activities was observed following cold acclimation in either the presence or absence of exogenous thyroid hormones. Collectively, our results indicate that thyroid hormones influence the activity of oxidative enzymes more strongly in warm-acclimated than in cold-acclimated lake whitefish, and they may play a role in mediating metabolic adjustments observed during thermal acclimation. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Fully Aromatic Block Copolymers for Fuel Cell Membranes with Densely Sulfonated Nanophase Domains

    DEFF Research Database (Denmark)

    Takamuku, Shogo; Jannasch, Patrick; Lund, Peter Brilner

    Two multiblock copoly(arylene ether sulfone)s with similar block lengths and ion exchange capacities (IECs) were prepared by a coupling reaction between a non-sulfonated precursor block and a highly sulfonated precursor block containing either fully disulfonated diarylsulfone or fully...... tetrasulfonated tetraaryldisulfone segments. The latter two precursor blocks were sulfonated via lithiation-sulfination reactions whereby the sulfonic acid groups were exclu- sively placed in ortho positions to the many sulfone bridges, giving these locks IECs of 4.1 and 4.6 meqg1, respectively. Copolymer...

  13. Structure-Activity Relationship Analysis of 3-phenylcoumarin-Based Monoamine Oxidase B Inhibitors

    Science.gov (United States)

    Rauhamäki, Sanna; Postila, Pekka A.; Niinivehmas, Sanna; Kortet, Sami; Schildt, Emmi; Pasanen, Mira; Manivannan, Elangovan; Ahinko, Mira; Koskimies, Pasi; Nyberg, Niina; Huuskonen, Pasi; Multamäki, Elina; Pasanen, Markku; Juvonen, Risto O.; Raunio, Hannu; Huuskonen, Juhani; Pentikäinen, Olli T.

    2018-03-01

    Monoamine oxidase B (MAO-B) catalyzes deamination of monoamines such as neurotransmitters dopamine and norepinephrine. Accordingly, small-molecule MAO-B inhibitors potentially alleviate the symptoms of dopamine-linked neuropathologies such as depression or Parkinson’s disease. Coumarin with a functionalized 3-phenyl ring system is a promising scaffold for building potent MAO-B inhibitors. Here, a vast set of 3-phenylcoumarin derivatives was designed using virtual combinatorial chemistry or rationally de novo and synthesized using microwave chemistry. The derivatives inhibited the MAO-B at 100 nM - 1 µM. The IC50 value of the most potent derivative 1 was 56 nM. A docking-based structure-activity relationship analysis summarizes the atom-level determinants of the MAO-B inhibition by the derivatives. Finally, the cross-reactivity of the derivatives was tested against monoamine oxidase A and a specific subset of enzymes linked to estradiol metabolism, known to have coumarin-based inhibitors. Overall, the results indicate that the 3-phenylcoumarins, especially derivative 1, present unique pharmacological features worth considering in future drug development.

  14. Preparation of a Sulfonated Carbonaceous Material from Lignosulfonate and Its Usefulness as an Esterification Catalyst

    Directory of Open Access Journals (Sweden)

    Duckhee Lee

    2013-07-01

    Full Text Available Sulfonated carbonaceous material useful as a solid acid catalyst was prepared from lignosulfonate, a waste of the paper-making industry sulfite pulping process, and characterized by 13C-NMR, FT-IR, TGA, SEM and elemental analysis, etc. The sulfonic acid group density and total density of all acid groups in the sulfonated carbonaceous material was determined by titration to be 1.24 mmol/g and 5.90 mmol/g, respectively. Its catalytic activity in the esterification of cyclohexanecarboxylic acid with anhydrous ethanol was shown to be comparable to that of the ionic exchange resin Amberlyst-15, when they were used in the same amount. In the meantime, the sulfonic acid group was found to be leached out by 26%–29% after it was exposed to hot water (95 °C for 5 h. The catalytic usefulness of the prepared carbonaceous material was investigated by performing esterifications.

  15. Investigation of sulfonated polysulfone membranes as electrolyte in a passive-mode direct methanol fuel cell mini-stack

    Energy Technology Data Exchange (ETDEWEB)

    Lufrano, F.; Baglio, V.; Staiti, P.; Stassi, A.; Arico, A.S.; Antonucci, V. [CNR - ITAE, Istituto di Tecnologie Avanzate per l' Energia ' ' Nicola Giordano' ' , Via Salita S. Lucia sopra Contesse n. 5 - 98126 S. Lucia - Messina (Italy)

    2010-12-01

    This paper reports on the development of polymer electrolyte membranes (PEMs) based on sulfonated polysulfone for application in a DMFC mini-stack operating at room temperature in passive mode. The sulfonated polysulfone (SPSf) with two degrees of sulfonation (57 and 66%) was synthesized by a well-known sulfonation process. SPSf membranes with different thicknesses were prepared and investigated. These membranes were characterized in terms of methanol/water uptake, proton conductivity, and fuel cell performance in a DMFC single cell and mini-stack operating at room temperature. The study addressed (a) control of the synthesis of sulfonated polysulfone, (b) optimization of the assembling procedure, (c) a short lifetime investigation and (d) a comparison of DMFC performance in active-mode operation vs. passive-mode operation. The best passive DMFC performance was 220 mW (average cell power density of about 19 mW cm{sup -2}), obtained with a thin SPSf membrane (70 {mu}m) at room temperature, whereas the performance of the same membrane-based DMFC in active mode was 38 mW cm{sup -2}. The conductivity of this membrane, SPSf (IEC = 1.34 mequiv. g{sup -1}) was 2.8 x 10{sup -2} S cm{sup -1}. A preliminary short-term test (200 min) showed good stability during chrono-amperometry measurements. (author)

  16. Study of sulfonated polyether ether ketone with pendant lithiated fluorinated sulfonic groups as ion conductive binder in lithium-ion batteries

    Science.gov (United States)

    Wei, Zengbin; Xue, Lixin; Nie, Feng; Sheng, Jianfang; Shi, Qianru; Zhao, Xiulan

    2014-06-01

    In an attempt to reduce the Li+ concentration polarization and electrolyte depletion from the electrode porous space, sulfonated polyether ether ketone with pendant lithiated fluorinated sulfonic groups (SPEEK-FSA-Li) is prepared and attempted as ionic conductivity binder. Sulfonated aromatic poly(ether ether ketone) exhibits strong adhesion and chemical stability, and lithiated fluorinated sulfonic side chains help to enhance the ionic conductivity and Li+ ion diffusion due to the charge delocalization over the sulfonic chain. The performances are evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, charge-discharge cycle testing, 180° peel testing, and compared with the cathode prepared with polyvinylidene fluoride binder. The electrode prepared with SPEEK-FSA-Li binder forms the relatively smaller resistances of both the SEI and the charge transfer of lithium ion transport. This is beneficial to lithium ion intercalation and de-intercalation of the cathode during discharging-charging, therefore the cell prepared with SPEEK-FSA-Li shows lower charge plateau potential and higher discharge plateau potential. Compared with PVDF, the electrode with ionic binder shows smaller decrease in capacity with the increasing of cycle rate. Meanwhile, adhesion strength of electrode prepared with SPEEK-FSA-Li is more than five times greater than that with PVDF.

  17. Enhanced antifouling and antibacterial properties of poly (ether sulfone) membrane modified through blending with sulfonated poly (aryl ether sulfone) and copper nanoparticles

    Science.gov (United States)

    Zhang, Jingjing; Xu, Ya'nan; Chen, Shouwen; Li, Jiansheng; Han, Weiqing; Sun, Xiuyun; Wu, Dihua; Hu, Zhaoxia; Wang, Lianjun

    2018-03-01

    A series of novel blend ultrafiltration (UF) membranes have been successfully prepared from commercial poly (ether sulfone), lab-synthesized sulfonated poly (aryl ether sulfone) (SPAES, 1 wt%) and copper nanoparticles (0 ∼ 0.4 wt%) via immersion precipitation phase conversion. The micro-structure and separation performance of the membranes were characterized by field emission scanning electron microscopy (SEM) and cross-flow filtration experiments, respectively. Sodium alginate, bovine serum albumin and humic acid were chosen as model organic foulants to investigate the antifouling properties, while E. coil was used to evaluate the antibacterial property of the fabricated membranes. By the incorporation with SPAES and copper nanoparticles, the hydrophilicity, antifouling and antibacterial properties of the modified UF membranes have been profoundly improved. At a copper nanoparticles content of 0.4 wt%, the PES/SPAES/nCu(0.4) membrane exhibited a high pure water flux of 193.0 kg/m2 h, reaching the smallest contact angle of 52°, highest flux recovery ratio of 79% and largest antibacterial rate of 78.9%. Furthermore, the stability of copper nanoparticles inside the membrane matrix was also considerably enhanced, the copper nanoparticles were less than 0.08 mg/L in the effluent during the whole operation.

  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. Synthesis and Characterization of Sulfonated Graphene Oxide Reinforced Sulfonated Poly (Ether Ether Ketone (SPEEK Composites for Proton Exchange Membrane Materials

    Directory of Open Access Journals (Sweden)

    Ning Cao

    2018-03-01

    Full Text Available As a clean energy utilization device, full cell is gaining more and more attention. Proton exchange membrane (PEM is a key component of the full cell. The commercial-sulfonated, tetrafluoroethylene-based fluoropolymer-copolymer (Nafion membrane exhibits excellent proton conductivity under a fully humidified environment. However, it also has some disadvantages in practice, such as high fuel permeability, a complex synthesis process, and high cost. To overcome these disadvantages, a low-cost and novel membrane was developed. The sulfonated poly (ether ether ketone (SPEEK was selected as the base material of the proton exchange membrane. Sulfonated graphene (SG was cross-linked with SPEEK through the elimination reaction of hydrogen bonds. It was found that the sulfonic acid groups and hydrophilic oxygen groups increased obviously in the resultant membrane. Compared with the pure SPEEK membrane, the SG-reinforced membrane exhibited better proton conductivity and methanol permeability prevention. The results indicate that the SG/SPEEK could be applied as a new proton exchange membrane in fuel cells.

  1. 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.

  2. 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.

  3. Structure and properties of compositions based on petroleum sulfonic acids

    Energy Technology Data Exchange (ETDEWEB)

    Tutorskii, I.A.; Sultanova, A.S.; Belkina, E.V.; Fomin, A.G. [Lomonosov Academy of Fine Chemical Technology, Moscow (Russian Federation)

    1995-03-01

    Colloidal characteristics of compositions based on petroleum sulfonic acids were studied. Neutralized heavy oil residue exhibits surface-active properties and contains an ultradisperse filler. Analysis of the compositions by size-exclusion-chromatography shows deep structural changes in the heavy acid residue upon neutralization with calcium carbonate.

  4. Toltrazuril sulfone sodium salt: synthesis, analytical detection, and pharmacokinetics in the horse.

    Science.gov (United States)

    Dirikolu, L; Karpiesiuk, W; Lehner, A F; Tobin, T

    2012-06-01

    Toltrazuril sulfone (ponazuril) is a triazine-based antiprotozoal agent with clinical application in the treatment of equine protozoal myeloencephalomyelitis (EPM). In this study, we synthesized and determined the bioavailability of a sodium salt formulation of toltrazuril sulfone that can be used for the treatment and prophylaxis of EPM in horses. Toltrazuril sulfone sodium salt was rapidly absorbed, with a mean peak plasma concentration of 2400 ± 169 (SEM) ng/mL occurring at 8 h after oral-mucosal dosing and was about 56% bioavailable compared with the i.v. administration of toltrazuril sulfone in dimethylsulfoxide (DMSO). The relative bioavailability of toltrazuril sulfone suspended in water compared with toltrazuril sulfone sodium salt was 46%, indicating approximately 54% less oral bioavailability of this compound suspended in water. In this study, we also investigated whether this salt formulation of toltrazuril sulfone can be used as a feed additive formulation without significant reduction in oral bioavailability. Our results indicated that toltrazuril sulfone sodium salt is relatively well absorbed when administered with feed with a mean oral bioavailability of 52%. Based on these data, repeated oral administration of toltrazuril sulfone sodium salt with or without feed will yield effective plasma and cerebrospinal fluid (CSF) concentrations of toltrazuril sulfone for the treatment and prophylaxis of EPM and other protozoal diseases of horses and other species. As such, toltrazuril sulfone sodium salt has the potential to be used as feed additive formulations for both the treatment and prophylaxis of EPM and various other apicomplexan diseases. © 2011 Blackwell Publishing Ltd.

  5. Preparation and study of novel poly(sulfone-ester-amide)s

    Energy Technology Data Exchange (ETDEWEB)

    Bruma, M. [Institute of Macromolecular Chemistry, Isai (Romania)], Mercer, F. [Raychem Corporation, Menlo Park, CA (United States); Gronewald, S. [Southwest Texas State Univ., San Marcos, TX (United States)] [and others

    1995-12-31

    A series of novel poly(ester-amide)s containing sulfone groups in the main chain have been prepared and compared with related polymers which do not have sulfone bridges. Incorporation of sulfone moieties into the polymer backbone improved the solubility of these polymers without significant loss of their high thermal stability, and provided a large {open_quotes}window{close_quotes} between T{sub g} and decomposition temperature. Solutions of poly(sulfone-ester-amide)s in NMP have been cast into flexible films, having low dielectric constant. The synthesis and characterization of these new polymers will be presented.

  6. Modulating effect of new potential antimelanomic agents, spin-labeled triazenes and nitrosoureas on the DOPA-oxidase activity of tyrosinase.

    Science.gov (United States)

    Gadjeva, V; Zheleva, A; Raikova, E

    1999-07-01

    The modulating effect of newly synthesized alkylating spin labeled triazene and spin labeled nitrosourea derivatives on the DOPA-oxidase activity of mushroom tyrosinase has been investigated by Bumett's spectrophotometric method (Burnett et al., 1967). All spin labeled triazenes have exhibited activating effect on DOPA-oxidase activity of tyrosinase, whereas clinically used triazene (DTIC), which does not contain nitroxide moiety, have showed inhibiting effect. At the same experimental conditions the spin labeled aminoacid nitrosoureas have showed dual effect - activating, in the beginning of the enzyme reaction and inhibiting later on. It is deduced that the activating effect of the spin labeled compounds is due to the nitroxide moiety and the inhibiting effect of all compounds depends on their half-life time. This study might contribute to make more clear the mechanism of action of the new compounds and on the other hand would come in quite useful as a preliminary prognosis for their antimelanomic activity.

  7. Graphene/activated carbon supercapacitors with sulfonated-polyetheretherketone as solid-state electrolyte and multifunctional binder

    Science.gov (United States)

    Chen, Y.-R.; Chiu, K.-F.; Lin, H. C.; Chen, C.-L.; Hsieh, C. Y.; Tsai, C. B.; Chu, B. T. T.

    2014-11-01

    Sulfonated polyetheretherketone (SPEEK) has been synthesised by sulphonation process and used as the solid-state electrolyte, binder and surfactant for supercapacitors. Reduced graphene dispersed by SPEEK is used as a high-efficiency conducting additive in solid-state supercapacitors. It is found that SPEEK can improve the stability of the reduced graphene dispersion significantly, and therefore, the solid-state supercapacitors show a large decrease in IR drop and charge-transfer resistance (Rct), resulting in a higher rate capability. The solid-state supercapacitors with the activated carbon/reduced graphene/SPEEK/electrode can be operated from 1 to 8 A/g and exhibit capacity retention of 93%. The noteworthy is more than twice higher value for capacity retention by comparison with the solid-state supercapacitors using activated carbon/reduced graphene/PVDF electrode (capacity retention is 36%). The cell of reduced graphene with SPEEK can be cycled over 5000 times at 5 A/g with no capacitance fading.

  8. Preliminary pharmacological studies on Eugenia uniflora leaves: xanthine oxidase inhibitory activity.

    Science.gov (United States)

    Schmeda-Hirschmann, G; Theoduloz, C; Franco, L; Ferro, E; de Arias, A R

    1987-11-01

    Eugenia uniflora is widely used in Paraguayan folk medicine. A hydroalcoholic extract of the leaves showed some central nervous system activity in hippocratic screening when given intraperitoneally, but little to no acute or subacute toxicity in doses up to 4200 mg/kg orally in BALB c mice. The LD50 of the extract was 220 mg/kg i.p. in mice. A decoction or infusion of the leaves is recommended for treating gout by native herbalists. The known flavonoids quercitrin, quercetin, myricitrin and myricetin were found to be responsible for the xanthine oxidase inhibitory action of the plant extract.

  9. 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.

  10. Toward High-Performance Lithium-Sulfur Batteries: Upcycling of LDPE Plastic into Sulfonated Carbon Scaffold via Microwave-Promoted Sulfonation.

    Science.gov (United States)

    Kim, Patrick J; Fontecha, Harif D; Kim, Kyungho; Pol, Vilas G

    2018-05-02

    Lithium-sulfur batteries were intensively explored during the last few decades as next-generation batteries owing to their high energy density (2600 Wh kg -1 ) and effective cost benefit. However, systemic challenges, mainly associated with polysulfide shuttling effect and low Coulombic efficiency, plague the practical utilization of sulfur cathode electrodes in the battery market. To address the aforementioned issues, many approaches have been investigated by tailoring the surface characteristics and porosities of carbon scaffold. In this study, we first present an effective strategy of preparing porous sulfonated carbon (PSC) from low-density polyethylene (LDPE) plastic via microwave-promoted sulfonation. Microwave process not only boosts the sulfonation reaction of LDPE but also induces huge amounts of pores within the sulfonated LDPE plastic. When a PSC layer was utilized as an interlayer in lithium-sulfur batteries, the sulfur cathode delivered an improved capacity of 776 mAh g -1 at 0.5C and an excellent cycle retention of 79% over 200 cycles. These are mainly attributed to two materialistic benefits of PSC: (a) porous structure with high surface area and (b) negatively charged conductive scaffold. These two characteristics not only facilitate the improved electrochemical kinetics but also effectively block the diffusion of polysulfides via Coulomb interaction.

  11. Direct catalytic olefination of alcohols with sulfones.

    Science.gov (United States)

    Srimani, Dipankar; Leitus, Gregory; Ben-David, Yehoshoa; Milstein, David

    2014-10-06

    The synthesis of terminal, as well as internal, olefins was achieved by the one-step olefination of alcohols with sulfones catalyzed by a ruthenium pincer complex. Furthermore, performing the reaction with dimethyl sulfone under mild hydrogen pressure provides a direct route for the replacement of alcohol hydroxy groups by methyl groups in one step. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. 21 CFR 177.2210 - Ethylene polymer, chloro-sulfonated.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene polymer, chloro-sulfonated. 177.2210... as Components of Articles Intended for Repeated Use § 177.2210 Ethylene polymer, chloro-sulfonated. Ethylene polymer, chlorosulfonated as identified in this section may be safely used as an article or...

  13. Polyether sulfone membrane modeling and construction for the ...

    African Journals Online (AJOL)

    Polyether sulfone membrane modeling and construction for the removal of nitrate from water using ion interference sulfate and iron nano-particle. ... The aim of this study was constructed the polyether sulfone membrane and modelling it, and for checking impact pressure, the amount of iron nanoparticles and sulfate iron ...

  14. 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.

  15. Molecular Basis for Converting (2S-Methylsuccinyl-CoA Dehydrogenase into an Oxidase

    Directory of Open Access Journals (Sweden)

    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. Anaerobic degradation of linear alkylbenzene sulfonate

    DEFF Research Database (Denmark)

    Mogensen, Anders Skibsted; Haagensen, Frank; Ahring, Birgitte Kiær

    2003-01-01

    Linear alkylbenzene sulfonate (LAS) found in wastewater is removed in the wastewater treatment facilities by sorption and aerobic biodegradation. The anaerobic digestion of sewage sludge has not been shown to contribute to the removal. The concentration of LAS based on dry matter typically...... increases during anaerobic stabilization due to transformation of easily degradable organic matter. Hence, LAS is regarded as resistant to biodegradation under anaerobic conditions. We present data from a lab-scale semi-continuously stirred tank reactor (CSTR) spiked with linear dodecylbenzene sulfonate (C...

  17. Preparation of new proton exchange membranes using sulfonated poly(ether sulfone) modified by octylamine (SPESOS)

    International Nuclear Information System (INIS)

    Mabrouk, W.; Ogier, L.; Matoussi, F.; Sollogoub, C.; Vidal, S.; Dachraoui, M.; Fauvarque, J.F.

    2011-01-01

    Highlights: → New, simple and cheap way to synthesize a membrane. → The membranes combine good proton conductivities with good mechanical properties. → The membrane performances in a fuel cell are similar to the Nafion 117. - Abstract: Sulfonated poly(arylene ether sulfone) (SPES) has received considerable attention in membrane preparation for proton exchange membrane fuel cell (PEMFC). But such membranes are brittle and difficult to handle in operation. We investigated new membranes using SPES grafted with various degrees of octylamine. Five new materials made from sulfonated polyethersulfone sulfonamide (SPESOS) were synthetized with different grades of grafting. They were made from SPES, with initially an ionic exchange capacity (IEC) of 2.4 meq g -1 (1.3 H + per monomer unit). Pristine SPES with that IEC is water swelling and becomes soluble at 80 deg. C, its proton conductivity is in the range of 0.1 S cm -1 at room temperature in aqueous H 2 SO 4 1 M, similar to that of Nafion. After grafting with various amounts of octylamine, the material is water insoluble; membranes are less brittle and show sufficient ionic conductivity. Proton transport numbers were measured close to 1.

  18. Immobilization of Acidithiobacillus ferrooxidans on sulfonated microporous poly(styrene-divinylbenzene) copolymer with granulated activated carbon and its use in bio-oxidation of ferrous iron.

    Science.gov (United States)

    Koseoglu-Imer, Derya Yuksel; Keskinler, Bulent

    2013-01-01

    The immobilization efficiencies of Acidithiobacillus ferrooxidans cells on different immobilization matrices were investigated for biooxidation of ferrous iron (Fe(2+)) to ferric iron (Fe(3+)). Six different matrices were used such as the polyurethane foam (PUF), granular activated carbon (GAC), raw poly(styrene-divinylbenzene) copolymer (rawSDVB), raw poly(styrene-divinylbenzene) copolymer with granular activated carbon (rawSDVB-GAC), sulfonated poly(styrene-divinylbenzene) copolymer (sulfSDVB) and sulfonated poly(styrene-divinylbenzene) copolymer with granular activated carbon (sulfSDVB-GAC). The sulfSDVB-GAC polymer showed the best performance for Fe(2+) biooxidation. It was used at packed-bed bioreactor and the kinetic parameters were obtained. The highest Fe(2+) biooxidation rate (R) was found to be 4.02 g/L h at the true dilution rate (Dt) of 2.47 1/h and hydraulic retention time (τ) of 0.4 h. The sulfSDVB-GAC polymer was used for the first time as immobilization material for A. ferrooxidans for Fe(2+) biooxidation. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. 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.

  20. Evaluation of Antimicrobial Activity of Glucose Oxidase from Aspergillus niger EBL-A and Penicillium notatum

    OpenAIRE

    Zia, Muhammad Anjum; Riaz, Ayesha; Rasul, Samreen; Abbas, Rao Zahid

    2013-01-01

    This work aimed to study the production and purification of glucose oxidase by Aspergillus niger and Penicillium notatum using corn steep liquor as the substrate and evaluate its antimicrobial activity for use in pharmaceutical and food industries. The enzyme was purified by ammonium sulfate precipitation (60-85%), DEAE-cellulose ion exchange and Sephadex G-200 size exclusion chromatography. The crude enzyme extracts of A. niger and P. notatum showed 2.32 and 5.53 U mg-1 specific activities, ...

  1. Isolation, Identification, and Xanthine Oxidase Inhibition Activity of Alkaloid Compound from Peperomia pellucida

    Science.gov (United States)

    Fachriyah, E.; Ghifari, M. A.; Anam, K.

    2018-04-01

    The research of the isolation and xanthine oxidation inhibition activity of alkaloid compound from Peperomia pellucida has been carried out. Alkaloid extract is isolated by column chromatography and preparative TLC. Alkaloid isolate is identified spectroscopically by UV-Vis spectrophotometer, FT-IR, and LC-MS/MS. Xanthine oxidase inhibition activity is carried out by in vitro assay. The result showed that the alkaloid isolated probably has piperidine basic structure. The alkaloid isolate has N-H, C-H, C = C, C = O, C-N, C-O-C groups and the aromatic ring. The IC50 values of ethanol and alkaloid extract are 71.6658 ppm and 76.3318 ppm, respectively. Alkaloid extract of Peperomia pellucida showed higher activity than ethanol extract.

  2. Evaluation of Sulfonate-Based Collectors with Different Hydrophobic Tails for Flotation of Fluorite

    Directory of Open Access Journals (Sweden)

    Renji Zheng

    2018-02-01

    Full Text Available This investigation aims to demonstrate the effects of hydrophobic tails on the affinity and relevant flotation response of sulfonate-based collectors for fluorite. For this purpose, a series of alkyl sulfonates with different hydrophobic tails, namely sodium decanesulfonate (C10, sodium dodecylsulfate (C12, sodium hexadecanesulfonate (C16, and sodium dodecylbenzenesulfonate (C12B were applied. The flotation tests showed that C12 and C12B had a better collecting performance than C10 and C16 at pH < 10, and the flotation recovery of fluorite was higher when adopting C12B as a collector compared with C12 with a strong base. The adsorption behaviors of collectors on the fluorite surface were studied through zeta potential, Fourier transform infrared (FTIR, and X-ray photoelectron spectroscopy (XPS analyses. It was found that the affinity of alkyl sulfonates for fluorite was enhanced with the increase of the alkyl chain length from C10 to C16. The existence of phenyl in the hydrophobic tail of sulfonates could improve its activity for fluorite by reducing its surface tension. The abnormal phenomenon C16 with a high affinity for fluorite had a low collecting performance for fluorite mainly due to its overlong alkyl chain, resulting in low solubility in pulp, which restrained its interaction with fluorite. We concluded that C12B was the most applicable collector for fluorite among these reagents due to its high activity, high solubility, and low cost, which was further substantiated by calculating their molecular frontier orbital energy.

  3. Decolorization and biodegradation of remazol brilliant blue R by bilirubin oxidase.

    Science.gov (United States)

    Liu, Youxun; Huang, Juan; Zhang, Xiaoyu

    2009-12-01

    The dye-decolorizing potential of bilirubin oxidase (BOX) was demonstrated for an anthraquinone dye, remazol brilliant blue R (RBBR). The dye was decolorized 40% within 4 h by the BOX alone, whereas it was more efficient in the presence of 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), showing 91.5% decolorization within 25 min. The effects of operational parameters on decolorization were examined. The results showed that the decolorization efficiency decreased with increasing RBBR concentration, and a marked inhibition effect was exhibited when the dye concentrations were above 100 mg l(-1). The optimum temperature for enzymatic decolorization was 40 degrees C. BOX showed efficient decolorization of the dye with a wide pH range of 5-8.5. The maximum decolorization activity occurred at pH 8 with ABTS and at pH 5 without ABTS. Analysis of RBBR ultraviolet and visible (UV-VIS) spectra after BOX treatment indicated that the decolorization of RBBR was due to biodegradation. Our results suggested that ABTS can serve as an electron mediator to facilitate the oxidation of RBBR, and the BOX-ABTS mediator-involved dye decolorization mechanism was similar to that of laccase. Operation over a wide range of pH and efficient decolorization suggested that the BOX can be used to decolorize synthetic dyes from effluents, especially for anthraquinonic dyes.

  4. 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.

  5. 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.

  6. Structure–Activity Relationship of Xanthones as Inhibitors of Xanthine Oxidase

    Directory of Open Access Journals (Sweden)

    Ling-Yun Zhou

    2018-02-01

    Full Text Available Polygala plants contain a large number of xanthones with good physiological activities. In our previous work, 18 xanthones were isolated from Polygala crotalarioides. Extented study of the chemical composition of the other species Polygala sibirica led to the separation of two new xanthones—3-hydroxy-1,2,6,7,8-pentamethoxy xanthone (A and 6-O-β-d-glucopyranosyl-1,7-dimethoxy xanthone (C—together with 14 known xanthones. Among them, some xanthones have a certain xanthine oxidase (XO inhibitory activity. Furthemore, 14 xanthones as XO inhibitors were selected to develop three-dimensional quantitative structure–activity relationship (3D-QSAR using comparative molecular field analysis (CoMFA and comparative molecular similarity indices analysis (CoMSIA models. The CoMFA model predicted a q2 value of 0.613 and an r2 value of 0.997. The best CoMSIA model predicted a q2 value of 0.608 and an r2 value of 0.997 based on a combination of steric, electrostatic, and hydrophobic effects. The analysis of the contour maps from each model provided insight into the structural requirements for the development of more active XO inhibitors.

  7. 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.

  8. 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.

  9. 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

  10. NAD(P)H oxidase/nitric oxide interactions in peroxisome proliferator activated receptor (PPAR)α-mediated cardiovascular effects

    International Nuclear Information System (INIS)

    Newaz, Mohammad; Blanton, Ahmad; Fidelis, Paul; Oyekan, Adebayo

    2005-01-01

    Activation of peroxisome proliferator activated receptor (PPAR)α and its protective role in cardiovascular function has been reported but the exact mechanism(s) involved is not clear. As we have shown that PPARα ligands increased nitric oxide (NO) production and cardiovascular function is controlled by a balance between NO and free radicals, we hypothesize that PPARα activation tilts the balance between NO and free radicals and that this mechanism defines the protective effects of PPARα ligands on cardiovascular system. Systolic blood pressure (SBP) was greater in PPARα knockout (KO) mice compared with its wild type (WT) litter mates (130 ± 10 mmHg versus 107 ± 4 mmHg). L-NAME (100 mg/L p.o.), the inhibitor of NO production abolished the difference between PPARα KO and WT mice. In kidney homogenates, tissue lipid hydroperoxide generation was greater in KO mice (11.8 ± 1.4 pM/mg versus 8.3 ± 0.6 pM/mg protein). This was accompanied by a higher total NOS activity (46 ± 6%, p 2+ -dependent NOS activity in kidney homogenates of untreated PPARα WT compared with the KO mice. Clofibrate, a PPARα ligand, increased NOS activity in WT but not KO mice. Bezafibrate (30 mg/kg) reduced SBP in conscious rats (19 ± 4%, p < 0.05), increased urinary NO excretion (4.06 ± 0.53-7.07 ± 1.59 μM/24 h; p < 0.05) and reduced plasma 8-isoprostane level (45.8 ± 15 μM versus 31.4 ± 8 μM), and NADP(H) oxidase activity (16 ± 5%). Implantation of DOCA pellet (20 mg s.c.) in uninephrectomized mice placed on 1% NaCl drinking water increased SBP by a margin that was markedly greater in KO mice (193 ± 13 mmHg versus 130 ± 12 mmHg). In the rat, DOCA increased SBP and NAD(P)H oxidase activity and both effects were diminished by clofibrate. In addition, clofibrate reduced ET-1 production in DOCA/salt hypertensive rats. Thus, apart from inhibition of ET-1 production, PPARα activation exerts protective actions in hypertension via a mechanism that involves NO production and

  11. NecroX-7 prevents oxidative stress-induced cardiomyopathy by inhibition of NADPH oxidase activity in rats

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joonghoon; Park, Eok; Ahn, Bong-Hyun; Kim, Hyoung Jin [LG Life Sciences Ltd., R and D Park, Daejeon, 305-380 (Korea, Republic of); Park, Ji-hoon [Department of Biochemistry, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Koo, Sun Young; Kwak, Hyo-Shin; Park, Heui Sul; Kim, Dong Wook; Song, Myoungsub; Yim, Hyeon Joo; Seo, Dong Ook [LG Life Sciences Ltd., R and D Park, Daejeon, 305-380 (Korea, Republic of); Kim, Soon Ha, E-mail: shakim@lgls.com [LG Life Sciences Ltd., R and D Park, Daejeon, 305-380 (Korea, Republic of)

    2012-08-15

    Oxidative stress is one of the causes of cardiomyopathy. In the present study, NecroXs, novel class of mitochondrial ROS/RNS scavengers, were evaluated for cardioprotection in in vitro and in vivo model, and the putative mechanism of the cardioprotection of NecroX-7 was investigated by global gene expression profiling and subsequent biochemical analysis. NecroX-7 prevented tert-butyl hydroperoxide (tBHP)-induced death of H9C2 rat cardiomyocytes at EC{sub 50} = 0.057 μM. In doxorubicin (DOX)-induced cardiomyopathy in rats, NecroX-7 significantly reduced the plasma levels of creatine kinase (CK-MB) and lactate dehydrogenase (LDH) which were increased by DOX treatment (p < 0.05). Microarray analysis revealed that 21 genes differentially expressed in tBHP-treated H9C2 cells were involved in ‘Production of reactive oxygen species’ (p = 0.022), and they were resolved by concurrent NecroX-7 treatment. Gene-to-gene networking also identified that NecroX-7 relieved cell death through Ncf1/p47phox and Rac2 modulation. In subsequent biochemical analysis, NecroX-7 inhibited NADPH oxidase (NOX) activity by 53.3% (p < 0.001). These findings demonstrate that NecroX-7, in part, provides substantial protection of cardiomyopathy induced by tBHP or DOX via NOX-mediated cell death. -- Highlights: ► NecroX-7 prevented tert-butyl hydroperoxide-induced in vitro cardiac cell death. ► NecroX-7 ameliorated doxorubicin-induced in vivo cardiomyopathy. ► NecroX-7 prevented oxidative stress and necrosis-enriched transcriptional changes. ► NecroX-7 effectively inhibited NADPH oxidase activation. ► Cardioprotection of Necro-7 was brought on by modulation of NADPH oxidase activity.

  12. Thermochemical stability of Soviet macroporous sulfonated cation-exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rukhlyada, N.N.; Plotnikova, V.P.; Roginskaya, B.S.; Znamenskii, Yu.P.; Zavodovskaya, A.S.; Dobrova, E.I.

    1988-10-20

    The purpose of this work was to study the influence of macroporosity on the thermochemical stability of sulfonated cation-exchangers. The investigations were carried out on commercial macroporous sulfonated cation-exchangers based on styrene-divinylbenzene copolymers. Study of the thermochemical stability of macroporous sulfonated cation-exchangers in dilute hydrogen peroxide solutions showed that the type of macroporosity has virtually no influence on their stability. The determining factor in thermal stability of macroporous cation-exchangers, as of the gel type, is the degree of cross-linking of the polymer matrix. The capacity loss of macroporous cation-exchangers during oxidative thermolysis is caused by destruction of the macromolecular skeleton and elution of fragments of polar chains containing sulfo groups into the solution.

  13. The peroxidase and oxidase-like activity of NiCo{sub 2}O{sub 4} mesoporous spheres: Mechanistic understanding and colorimetric biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Su, Li, E-mail: suli@htu.edu.cn [Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007 (China); Henan Key Laboratory of Green Chemical Media and Reactions, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Dong, Wenpei; Wu, Chengke; Gong, Yijun; Zhang, Yan; Li, Ling; Mao, Guojiang; Feng, Suling [Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007 (China); Henan Key Laboratory of Green Chemical Media and Reactions, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China)

    2017-01-25

    The synthesized NiCo{sub 2}O{sub 4} mesoporous spheres (MS) displayed intrinsic peroxidase and oxidase-like activity were firstly reported. The catalytic mechanism of the oxidase-like activity of NiCo{sub 2}O{sub 4} MS was analyzed in detail using the electron spin resonance (ESR) method. It is found that NiCo{sub 2}O{sub 4} MS could directly oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) but did not produce {sup 1}O{sub 2} and ·OH. And the mechanism of the peroxidase-like activity of NiCo{sub 2}O{sub 4} MS was also verified that the oxidation of TMB stemmed from not only ·OH but also {sup 1}O{sub 2}. Based on the NiCo{sub 2}O{sub 4} MS showed excellent peroxidase-like activity over a broad temperature range, especially at normal body temperature, a detection tool was designed for glucose determination in diabetics' serum samples. And this detection method based on NiCo{sub 2}O{sub 4} MS gave a lower limit of detection than the method using Co{sub 3}O{sub 4} NPs and NiO NPs, as the single-component oxides of NiCo{sub 2}O{sub 4}. Our study may open up the possibility to make a great influence on the next generation of enzyme mimetics system. - Highlights: • NiCo{sub 2}O{sub 4} MS were found to possess the peroxidase and oxidase-like activity. • The peroxidase-like activity of NiCo{sub 2}O{sub 4} MS was stemmed from not only ·OH but also {sup 1}O{sub 2}. • The oxidase-like activity may stem from NiCo{sub 2}O{sub 4} MS′ oxidation rather than ·OH and {sup 1}O{sub 2}. • A colorimetric detection tool is designed for glucose determination in serum samples.

  14. Sulfonated carbon black-based composite membranes for fuel cell

    Indian Academy of Sciences (India)

    Composite membranes were then prepared using S–C as fillers and sulfonated poly(ether ether ketone) (SPEEK) as polymer matrix with three different sulfonation degrees (DS = 60, 70 and 82%). Structure and properties of the composite membranes were characterized by FTIR, TGA, scanning electron microscopy, proton ...

  15. Engineering glucose oxidase to minimize the influence of oxygen on sensor response

    International Nuclear Information System (INIS)

    Horaguchi, Yohei; Saito, Shoko; Kojima, Katsuhiro; Tsugawa, Wakako; Ferri, Stefano; Sode, Koji

    2014-01-01

    Glucose oxidase (GOx) is an important industrial enzyme and is recognized as the gold standard for monitoring blood glucose. However, due to its inherent oxidase property, the presence of oxygen affects electrochemical measurements of venous blood glucose employing artificial electron mediators. We therefore attempted to engineer Penicillium amagasakiense-derived GOx into a dehydrogenase by focusing on the amino acid residues predicted to interact with oxygen. Our rational amino acid substitution approach resulted in the construction of the Ser114Ala/Phe355Leu mutant, which has an 11-fold decrease in oxidase activity and 2.8-fold increase in dehydrogenase activity compared with wild-type GOx. As a result, the dehydrogenase/oxidase activity ratio of the engineered enzyme was 32-fold greater than that of the wild-type enzyme. The enzyme sensor constructed with Ser114Ala/Phe355Leu was considerably less affected by oxygen than the wild-type GOx-based sensor at lower glucose concentrations

  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. 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.

  18. 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.

  19. Activity and functional interaction of alternative oxidase and uncoupling protein in mitochondria from tomato fruit

    Directory of Open Access Journals (Sweden)

    F.E. Sluse

    2000-03-01

    Full Text Available Cyanide-resistant alternative oxidase (AOX is not limited to plant mitochondria and is widespread among several types of protists. The uncoupling protein (UCP is much more widespread than previously believed, not only in tissues of higher animals but also in plants and in an amoeboid protozoan. The redox energy-dissipating pathway (AOX and the proton electrochemical gradient energy-dissipating pathway (UCP lead to the same final effect, i.e., a decrease in ATP synthesis and an increase in heat production. Studies with green tomato fruit mitochondria show that both proteins are present simultaneously in the membrane. This raises the question of a specific physiological role for each energy-dissipating system and of a possible functional connection between them (shared regulation. Linoleic acid, an abundant free fatty acid in plants which activates UCP, strongly inhibits cyanide-resistant respiration mediated by AOX. Moreover, studies of the evolution of AOX and UCP protein expression and of their activities during post-harvest ripening of tomato fruit show that AOX and plant UCP work sequentially: AOX activity decreases in early post-growing stages and UCP activity is decreased in late ripening stages. Electron partitioning between the alternative oxidase and the cytochrome pathway as well as H+ gradient partitioning between ATP synthase and UCP can be evaluated by the ADP/O method. This method facilitates description of the kinetics of energy-dissipating pathways and of ATP synthase when state 3 respiration is decreased by limitation of oxidizable substrate.

  20. An assay of optimal cytochrome c oxidase activity in fish gills.

    Science.gov (United States)

    Hu, Yau-Chung; Chung, Meng-Han; Lee, Tsung-Han

    2018-07-15

    Cytochrome c oxidase (COX) catalyzes the terminal oxidation reaction in the electron transport chain (ETC) of aerobic respiratory systems. COX activity is an important indicator for the evaluation of energy production by aerobic respiration in various tissues. On the basis of the respiratory characteristics of muscle, we established an optimal method for the measurement of maximal COX activity. To validate the measurement of cytochrome c absorbance, different ionic buffer concentrations and tissue homogenate protein concentrations were used to investigate COX activity. The results showed that optimal COX activity is achieved when using 50-100 μg fish gill homogenate in conjunction with 75-100 mM potassium phosphate buffer. Furthermore, we compared branchial COX activities among three species of euryhaline teleost (Chanos chanos, Oreochromis mossambicus, and Oryzias dancena) to investigate differences in aerobic respiration of osmoregulatory organs. COX activities in the gills of these three euryhaline species were compared with COX subunit 4 (COX4) protein levels. COX4 protein abundance and COX activity patterns in the three species occurring in environments with various salinities increased when fish encountered salinity challenges. This COX activity assay therefore provides an effective and accurate means of assessing aerobic metabolism in fish. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Electrooxidative Tandem Cyclization of Activated Alkynes with Sulfinic Acids To Access Sulfonated Indenones

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Jiangwei [The; Center; Shi, Wenyan [The; Zhang, Fan [The; Liu, Dong [The; Tang, Shan [The; Wang, Huamin [The; Lin, Xiao-Min [Center; Lei, Aiwen [The

    2017-05-25

    An,electrooxidative direct arylsulfonlylation of yones sulfintc acids via a radical tandem cyclization strategy has been developed for the construction of sulfonated ilicIenones:under oxidant, free conditions. This method provides a simple and efficient approach to prepare various sulfonylindenones in good to,excellent:Tyidds,, demonstrating the tremendous prospect of utilizing electrocatalysis in oxidative coupling, Notably, this reaction could Be easily scaled up with good, efficiency.

  2. 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.

  3. 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.

  4. 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 ...

  5. Radiation-induced crosslinking of poly(styrene–butadiene–styrene) block copolymers and their sulfonation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun-Young [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Song, Ju-Myung; Sohn, Joon-Yong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Shul, Yong-Gun [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Shin, Junhwa, E-mail: shinj@kaeri.re.kr [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of)

    2013-12-01

    Highlights: • The c-SBS films were prepared using a gamma ray or electron beam. • The crosslinking degree of the c-SBS films were increased with the irradiation dose. • The prepared c-SBS films were sulfonated with various concentration of CSA. • The sulfonation of the c-SBS film is largely dependent on the concentration of CSA. • The sulfonation process is progressed from the surface to the inner part of c-SBS film. -- Abstract: Several crosslinked poly(styrene–butadiene–styrene) (c-SBS) block copolymer films were prepared using a gamma ray or electron beam with various irradiation doses and the prepared c-SBS film was then subjected to sulfonation using a chlorosulfonic acid (CSA) solution to introduce a sulfonic acid group. To estimate the degree of crosslinking, the gel fractions and FT-IR spectra of the c-SBS films were used and the results indicate that the degree of crosslinking is increased with an increase in the radiation dose. The surface morphology and mechanical property of the c-SBS films were observed using SEM and UTM instruments, respectively. The sulfonated c-SBS films were investigated by measuring the ion exchange capacity (IEC) and by observing the cross-sectional distribution patterns of sulfonic acid group using an SEM-EDX instrument. The IEC and SEM-EDX studies indicate that the sulfonated c-SBS membranes can be successfully prepared through the radiation crosslinking of the SBS film and the subsequent sulfonation with a diluted CSA solution.

  6. 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

  7. 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)).

  8. Acute Ethanol Intake Induces NAD(P)H Oxidase Activation and Rhoa Translocation in Resistance Arteries.

    Science.gov (United States)

    Simplicio, Janaina A; Hipólito, Ulisses Vilela; Vale, Gabriel Tavares do; Callera, Glaucia Elena; Pereira, Camila André; Touyz, Rhian M; Tostes, Rita de Cássia; Tirapelli, Carlos R

    2016-11-01

    The mechanism underlying the vascular dysfunction induced by ethanol is not totally understood. Identification of biochemical/molecular mechanisms that could explain such effects is warranted. To investigate whether acute ethanol intake activates the vascular RhoA/Rho kinase pathway in resistance arteries and the role of NAD(P)H oxidase-derived reactive oxygen species (ROS) on such response. We also evaluated the requirement of p47phox translocation for ethanol-induced NAD(P)H oxidase activation. Male Wistar rats were orally treated with ethanol (1g/kg, p.o. gavage) or water (control). Some rats were treated with vitamin C (250 mg/kg, p.o. gavage, 5 days) before administration of water or ethanol. The mesenteric arterial bed (MAB) was collected 30 min after ethanol administration. Vitamin C prevented ethanol-induced increase in superoxide anion (O2-) generation and lipoperoxidation in the MAB. Catalase and superoxide dismutase activities and the reduced glutathione, nitrate and hydrogen peroxide (H2O2) levels were not affected by ethanol. Vitamin C and 4-methylpyrazole prevented the increase on O2- generation induced by ethanol in cultured MAB vascular smooth muscle cells. Ethanol had no effect on phosphorylation levels of protein kinase B (Akt) and eNOS (Ser1177 or Thr495 residues) or MAB vascular reactivity. Vitamin C prevented ethanol-induced increase in the membrane: cytosol fraction ratio of p47phox and RhoA expression in the rat MAB. Acute ethanol intake induces activation of the RhoA/Rho kinase pathway by a mechanism that involves ROS generation. In resistance arteries, ethanol activates NAD(P)H oxidase by inducing p47phox translocation by a redox-sensitive mechanism. O mecanismo da disfunção vascular induzido pelo consumo de etanol não é totalmente compreendido. Justifica-se, assim a identificação de mecanismos bioquímicos e moleculares que poderiam explicar tais efeitos. Investigar se a ingestão aguda de etanol ativa a via vascular RhoA/Rho quinase

  9. 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

  10. A quantitative histochemical study of D-amino acid oxidase activity in rat liver in relationship with feeding conditions

    NARCIS (Netherlands)

    Patel, H. R.; Frederiks, W. M.; Marx, F.; Best, A. J.; van Noorden, C. J.

    1991-01-01

    The histochemical method for the demonstration of D-amino acid oxidase activity in rat liver, based on the use of cerium ions and the diaminobenzidine-cobalt-hydrogen peroxide procedure, was improved by the application of unfixed cryostat sections and a semipermeable membrane interposed between

  11. Oil recovery with vinyl sulfonic acid-acrylamide copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Norton, C.J.; Falk, D.O.

    1973-12-18

    An aqueous polymer flood containing sulfomethylated alkali metal vinyl sulfonate-acrylamide copolymers was proposed for use in secondary or tertiary enhanced oil recovery. The sulfonate groups on the copolymers sustain the viscosity of the flood in the presence of brine and lime. Injection of the copolymer solution into a waterflooded Berea core, produced 30.5 percent of the residual oil. It is preferred that the copolymers are partially hydrolyzed.

  12. Electrochemical detection of dopamine using water-soluble sulfonated graphene

    International Nuclear Information System (INIS)

    Li, Su-Juan; He, Jun-Zhi; Zhang, Meng-Jie; Zhang, Rong-Xia; Lv, Xia-Lei; Li, Shao-Hua; Pang, Huan

    2013-01-01

    Graphical abstract: DPV responses of dopamine (DA) at sulfonated graphene based glassy carbon electrode in the presence of ascorbic acid (AA) and uric acid (UA). The separation of the oxidation peak potentials for AA-DA, DA-UA and UA-AA was about 227 mV, 125 mV and 352 mV, which allowed selectively determining DA. -- Abstract: In the present study, a biosensor was prepared using the water-soluble sulfonated graphene with the aim of achieving the selective and sensitive determination of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). The aromatic π–π stacking and electrostatic attraction between positively charged DA and negatively charged sulfonated graphene can accelerate the electron transfer whereas weakening AA and UA oxidation on the sulfonated graphene-modified electrode. Fourier transform infrared spectra (FTIR), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to characterize the successful synthesis of sulfonated graphene sheets. Differential pulse voltammetry was used for electrochemical detection, the separation of the oxidation peak potentials for AA-DA, DA-UA and UA-AA was about 227 mV, 125 mV and 352 mV, which allowed selectively determining DA. A broad linear range, low detection limit, along with good ability to suppress the background current from large excess ascorbic acid (AA) and uric acid (UA) were obtained. The as-prepared sulfonated graphene sheets exhibited superior performance over conventional negatively charged Nafion films, such as flexible film thickness, unique nanostructure, excellent anti-interference ability, high sensitivity and selectivity. The proposed method was used to detect DA in real hydrochloride injection sample, human urine and serum samples with satisfactory recovery results

  13. Direct esterification of olive-pomace oil using mesoporous silica supported sulfonic acids

    Directory of Open Access Journals (Sweden)

    F. Alrouh

    2017-02-01

    Full Text Available Mesoporous silica MCM-41 and SBA-15 containing propyl sulfonic acid groups were synthesized according to the literature and were characterized by X-ray diffraction, N2 adsorption and the H+ exchange capacities of the sulfonic acid groups were titrated. The esterification reaction of glycerol with olive-pomace oil has been carried out by using prepared functionalized mesoporous silica (MCM-41 and SBA-15 as catalysts. It has been monitored by GC two fatty acids (palmitic and oleic acids as reactants in olive-pomace oil and their related monoacylglycerols (Glycerol monopalmitate GMP and monooleate GMO as reaction product. The catalytic activities of the functionalized mesoporous silica were compared with commercial catalysts, these included homogeneous catalysts (p-toluenesulfonic acid and heterogeneous catalysts (Amberlyst-15. The total yield of monoacylglycerols (GMO + GMP was nearly 40%. Remarkably, we found that MCM-41-SO3H was recycled at least 3 times without any loss of activity.

  14. 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.

  15. Chemical labeling studies on isolated and vesicular bovine heart mitochondrial cytochrome c oxidase

    International Nuclear Information System (INIS)

    Venzke, K.S.; Reynolds, K.A.; Prochaska, L.J.

    1987-01-01

    Bovine heart cytochrome c oxidase dispersed in Triton X-100, Tween 80, or dodecyl maltoside was reacted with the water-soluble reagents [ 35 S]-diazonium benzene sulfonate (DABS) (10-100 μM) or [ 125 I]-iodo-DABS (34-55 nM) to map the surface topography of the enzyme in different protein aggregation states. Both reagents gave similar labeling profiles of the enzyme under all conditions. Subunits II, III, and VII were extensively labeled by DABS, while subunits I and VI were unreactive with DABS in each detergent. Subunit V exhibited an increase in DABS labeling when the enzyme was reacted in Tween 80 as compared to the enzyme in Triton X-100 or dodecyl maltoside. Also, components b and c showed an increase in DABS reactivity when the enzyme was modified in dodecyl maltoside. In general, the labeling profile of the enzyme in dodecyl maltoside resembled that of the enzyme in Triton X-100, emphasizing that the mechanism of dispersal of the enzyme by both detergents is similar. Cytochrome c oxidase incorporated into phosphatidylglycerol:phosphatidylcholine(1:20)(w:w) phospholipid vesicles (COV) by cholate dialysis was reacted with DABS and subunits II and III were significantly labeled. Approximately 65-70% of the enzyme in COV was oriented with the cytochrome c binding domain facing the extravesicular medium, as determined by comparison of the DABS labeling in subunit IV in detergent-lysed and intact COV

  16. Hexaaquamagnesium(II bis(d-camphor-10-sulfonate

    Directory of Open Access Journals (Sweden)

    Dejan Jeremić

    2008-07-01

    Full Text Available The structure of the title complex, [Mg(H2O6](C10H15O4S2, consists of regular octahedral [Mg(H2O6]2+ cations and d-camphor-10-sulfonate anions. A three-dimensional supramolecular architecture is formed via hydrogen-bond interactions [O—H...O = 2.723 (2–2.833 (2 Å] to give alternating layers of [Mg(H2O6]2+ cations and d-camphor-10-sulfonate anions. The title compound is isomorphous with the zinc, copper, cadmium and nickel analogues.

  17. D-amino acid oxidase activator gene (DAOA) variation affects cerebrospinal fluid homovanillic acid concentrations in healthy Caucasians

    DEFF Research Database (Denmark)

    Andreou, Dimitrios; Saetre, Peter; Werge, Thomas

    2012-01-01

    The D-amino acid oxidase activator (DAOA) protein regulates the function of D-amino oxidase (DAO), an enzyme that catalyzes the oxidative deamination of D-3,4-dihydroxyphenylalanine (D-DOPA) and D-serine. D-DOPA is converted to L-3,4-DOPA, a precursor of dopamine, whereas D-serine participates...... in glutamatergic transmission. We hypothesized that DAOA polymorphisms are associated with dopamine, serotonin and noradrenaline turnover in the human brain. Four single-nucleotide polymorphisms, previously reported to be associated with schizophrenia, were genotyped. Cerebrospinal fluid (CSF) samples were drawn...... by lumbar puncture, and the concentrations of the major dopamine metabolite homovanillic acid (HVA), the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and the major noradrenaline metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) were measured. Two of the investigated polymorphisms, rs...

  18. Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers

    NARCIS (Netherlands)

    Ruggeri, Giacomo; Passaglia, Elisa; Giorgi, Ivan; Picchioni, Francesco; Aglietto, Mauro

    2001-01-01

    Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing

  19. Surface reconstitution of glucose oxidase onto a norbornylogous bridge self-assembled monolayer

    International Nuclear Information System (INIS)

    Liu Jingquan; Paddon-Row, Michael N.; Gooding, J. Justin

    2006-01-01

    An electrode construct was fabricated in which a self-assembled monolayer containing a novel norbornylogous bridge was covalently attached to flavin adenine dinucleotide (FAD), the redox active centre of several oxidase enzymes. The electrochemistry of the construct was investigated before and after the reconstitution of glucose oxidase around the surface bound FAD. Rapid rates of electron transfer were observed both before and after the reconstitution of biocatalytically active enzyme. However, no biocatalytic activity was observed under anaerobic conditions suggesting the a lack of enzyme turnover through direct electron transfer. It is proposed that a decrease in the electronic coupling between the redox active FAD and the electrode following reconstitution of the glucose oxidase - a probable consequence of the FAD being immersed in a protein environment - was responsible for the inability of the enzyme to be turned over under anaerobic conditions

  20. Determination of trace elements by neutron activation analysis using dinonylnaphtalene sulfonic acid as a preconcentrating agent

    International Nuclear Information System (INIS)

    Yang, M.H.; Chen, P.Y.; Tseng, C.L.; Yeh, S.J.; Weng, P.S.

    1977-01-01

    Dinonylnaphthalene sulfonic acid (HD) has been used as a preconcentrating agent to enrich trace metal ions and to separate the interfering elements such as Na, K, Cl and Br, which normally exist in the natural aqueous systems. Experiments were performed by extracting the ions in the aqueous medium with HD in n-hexane and subsequently backextracted into a minimal volume of acid solution. Factors influencing the extraction efficiency of the ions of interest were investigated. The preconcentration technique has been successfully applied to the determination by neutron activation analysis of trace elements in natural water and biological materials. Both short-lived nuclides (Mg, Al, Ca, Mn) and long-lived nuclides (Sm, Eu, Zn, La, Cr, Sc, Fe, Co) in the ppb-level concentrations were determined. (T.G.)

  1. 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.

  2. Sulfonated Holey Graphene Oxide (SHGO) Filled Sulfonated Poly(ether ether ketone) Membrane: The Role of Holes in the SHGO in Improving Its Performance as Proton Exchange Membrane for Direct Methanol Fuel Cells.

    Science.gov (United States)

    Jiang, Zhong-Jie; Jiang, Zhongqing; Tian, Xiaoning; Luo, Lijuan; Liu, Meilin

    2017-06-14

    Sulfonated holey graphene oxides (SHGOs) have been synthesized by the etching of sulfonated graphene oxides with concentrated HNO 3 under the assistance of ultrasonication. These SHGOs could be used as fillers for the sulfonated aromatic poly(ether ether ketone) (SPEEK) membrane. The obtained SHGO-incorporated SPEEK membrane has a uniform and dense structure, exhibiting higher performance as proton exchange membranes (PEMs), for instance, higher proton conductivity, lower activation energy for proton conduction, and comparable methanol permeability, as compared to Nafion 112. The sulfonated graphitic structure of the SHGOs is believed to be one of the crucial factors resulting in the higher performance of the SPEEK/SHGO membrane, since it could increase the local density of the -SO 3 H groups in the membrane and induce a strong interfacial interaction between SHGO and the SPEEK matrix, which improve the proton conductivity and lower the swelling ratio of the membrane, respectively. Additionally, the proton conductivity of the membrane could be further enhanced by the presence of the holes in the graphitic planes of the SHGOs, since it provides an additional channel for transport of the protons. When used, direct methanol fuel cell with the SPEEK/SHGO membrane is found to exhibit much higher performance than that with Nafion 112, suggesting potential use of the SPEEK/SHGO membrane as the PEMs.

  3. Amyloid β induces NLRP3 inflammasome activation in retinal pigment epithelial cells via NADPH oxidase- and mitochondria-dependent ROS production.

    Science.gov (United States)

    Wang, Ke; Yao, Yong; Zhu, Xue; Zhang, Kai; Zhou, Fanfan; Zhu, Ling

    2017-06-01

    Amyloid β (Aβ)-induced chronic inflammation is believed to be a key pathogenic process in early-stage age-related macular degeneration (AMD). Nucleotide oligomerization domain (NOD)-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation triggered by Aβ is responsible for retinal pigment epithelium (RPE) dysfunction in the onset of AMD; however, the detailed molecular mechanism remains unclear. In this study, we investigated the involvement of NADPH oxidase- and mitochondria-derived reactive oxygen species (ROS) in the process of Aβ 1-40 -induced NLRP3 inflammasome activation in LPS-primed ARPE-19 cells. The results showed that Aβ 1-40 could induce excessive ROS generation, MAPK/NF-κB signaling activation and subsequently NLRP3 inflammasome activation in LPS-primed ARPE-19 cells. Furthermore, the inductive effect of Aβ 1-40 on NLRP3 inflammasome activation was mediated in a manner dependent on NADPH oxidase- and mitochondria-derived ROS. Our findings may provide a novel insight into the molecular mechanism by which Aβ contributes to the early-stage AMD. © 2016 Wiley Periodicals, Inc.

  4. Direct Olefination of Alcohols with Sulfones by Using Heterogeneous Platinum Catalysts.

    Science.gov (United States)

    Siddiki, S M A Hakim; Touchy, Abeda Sultana; Kon, Kenichi; Shimizu, Ken-Ichi

    2016-04-18

    Carbon-supported Pt nanoparticles (Pt/C) were found to be effective heterogeneous catalysts for the direct Julia olefination of alcohols in the presence of sulfones and KOtBu under oxidant-free conditions. Primary alcohols, including aryl, aliphatic, allyl, and heterocyclic alcohols, underwent olefination with dimethyl sulfone and aryl alkyl sulfones to give terminal and internal olefins, respectively. Secondary alcohols underwent methylenation with dimethyl sulfone. Under 2.5 bar H2, the same reaction system was effective for the transformation of alcohol OH groups to alkyl groups. Structural and mechanistic studies of the terminal olefination system suggested that Pt(0) sites on the Pt metal particles are responsible for the rate-limiting dehydrogenation of alcohols and that KOtBu may deprotonate the sulfone reagent. The Pt/C catalyst was reusable after the olefination, and this method showed a higher turnover number (TON) and a wider substrate scope than previously reported methods, which demonstrates the high catalytic efficiency of the present method. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Physical ageing and molecular mobilities of sulfonated polysulfone for proton exchange membranes

    Energy Technology Data Exchange (ETDEWEB)

    Lixon Buquet, C. [LECAP EA 4528, Institute for Materials Research FED 4114, Universite de Rouen, Avenue de l' Universite BP 12, 76801 Saint Etienne du Rouvray (France); PBS Department, UMR 6270 CNRS, MPBM, FR 3038, Universite de Rouen, Boulevard Maurice de Broglie, 76821 Mont Saint Aignan Cedex (France); Hamonic, F.; Saiter, A. [LECAP EA 4528, Institute for Materials Research FED 4114, Universite de Rouen, Avenue de l' Universite BP 12, 76801 Saint Etienne du Rouvray (France); Dargent, E., E-mail: eric.dargent@univ-rouen.fr [LECAP EA 4528, Institute for Materials Research FED 4114, Universite de Rouen, Avenue de l' Universite BP 12, 76801 Saint Etienne du Rouvray (France); Langevin, D.; Nguyen, Q.T. [PBS Department, UMR 6270 CNRS, MPBM, FR 3038, Universite de Rouen, Boulevard Maurice de Broglie, 76821 Mont Saint Aignan Cedex (France)

    2010-09-20

    The thermal behaviour, the physical ageing and the amorphous phase dynamics of polysulfone (PSU) and sulfonated polysulfone (SPSU) are characterized by thermogravimetric analysis and temperature modulated differential scanning calorimetry. The sulfonic group introduction (the sulfonation degree is 70%) in the polymer implies a drastic decrease of the thermal decomposition temperature (220 and 517 {sup o}C for SPSU and PSU respectively) and a modification of calorimetric parameters (for SPSU, the heat capacity in the glassy state is lower and the glass transition temperature T{sub g} is higher than for PSU). In terms of molecular dynamics, the amorphous phase heterogeneities are greater and the cooperative rearranging region size at the glass transition temperature is smaller for SPSU than for PSU. Moreover, after a physical ageing process, the enthalpy recovery kinetic has slowed down by sulfonation. These results can be explained from the existence of sulfonic domains confining the amorphous phase domains.

  6. Controlled fabrication of gold nanoparticles biomediated by glucose oxidase immobilized on chitosan layer-by-layer films

    International Nuclear Information System (INIS)

    Caseli, Luciano; Santos, David S. dos; Aroca, Ricardo F.; Oliveira, Osvaldo N.

    2009-01-01

    The control of size and shape of metallic nanoparticles is a fundamental goal in nanochemistry, and crucial for applications exploiting nanoscale properties of materials. We present here an approach to the synthesis of gold nanoparticles mediated by glucose oxidase (GOD) immobilized on solid substrates using the Layer-by-Layer (LbL) technique. The LbL films contained four alternated layers of chitosan and poly(styrene sulfonate) (PSS), with GOD in the uppermost bilayer adsorbed on a fifth chitosan layer: (chitosan/PSS) 4 /(chitosan/GOD). The films were inserted into a solution containing gold salt and glucose, at various pHs. Optimum conditions were achieved at pH 9, producing gold nanoparticles of ca. 30 nm according to transmission electron microscopy. A comparative study with the enzyme in solution demonstrated that the synthesis of gold nanoparticles is more efficient using immobilized GOD.

  7. NADPH oxidase 4-derived superoxide mediates flow-stimulated NKCC2 activity in thick ascending limbs.

    Science.gov (United States)

    Saez, Fara; Hong, Nancy J; Garvin, Jeffrey L

    2018-05-01

    Luminal flow augments Na + reabsorption in the thick ascending limb more than can be explained by increased ion delivery. This segment reabsorbs 30% of the filtered load of Na + , playing a key role in its homeostasis. Whether flow elevations enhance Na + -K + -2Cl - cotransporter (NKCC2) activity and the second messenger involved are unknown. We hypothesized that raising luminal flow augments NKCC2 activity by enhancing superoxide ([Formula: see text]) production by NADPH oxidase 4 (NOX4). NKCC2 activity was measured in thick ascending limbs perfused at either 5 or 20 nl/min with and without inhibitors of [Formula: see text] production. Raising luminal flow from 5 to 20 nl/min enhanced NKCC2 activity from 4.8 ± 0.9 to 6.3 ± 1.2 arbitrary fluorescent units (AFU)/s. Maintaining flow at 5 nl/min did not alter NKCC2 activity. The superoxide dismutase mimetic manganese (III) tetrakis (4-benzoic acid) porphyrin chloride blunted NKCC2 activity from 3.5 ± 0.4 to 2.5 ± 0.2 AFU/s when flow was 20 nl/min but not 5 nl/min. When flow was 20 nl/min, NKCC2 activity showed no change with time. The selective NOX1/4 inhibitor GKT-137831 blunted NKCC2 activity when thick ascending limbs were perfused at 20 nl/min from 7.2 ± 1.1 to 4.5 ± 0.8 AFU/s but not at 5 nl/min. The inhibitor also prevented luminal flow from elevating [Formula: see text] production. Allopurinol, a xanthine oxidase inhibitor, had no effect on NKCC2 activity when flow was 20 nl/min. Tetanus toxin prevents flow-induced stimulation of NKCC2 activity. We conclude that elevations in luminal flow enhance NaCl reabsorption in thick ascending limbs by stimulating NKCC2 via NOX4 activation and increased [Formula: see text]. NKCC2 activation is primarily the result of insertion of new transporters in the membrane.

  8. Nitric Acid Dehydration Using Perfluoro Carboxylate and Mixed Sulfonate/Carboxylate Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Ames, Richard L. [Colorado School of Mines, Golden, CO (United States)

    2004-09-01

    Perfluoro ionomer membranes are tetrafluoro ethylene-based materials with microheterogeneous structures consisting of a hydrophobic polymer backbone and a hydrophilic side-chain cluster region. Due to the ionomer cluster morphology, these films exhibit unique transport properties. Recent investigations with perfluoro sulfonate and perfluoro sulfonate/carboxylate composite polymers have demonstrated their value in the dehydration of nitric acid and they show potential as an alternative to conventional, energy intensive unit operations in the concentration of acid feeds. As a result, investigations were conducted to determine the feasibility of using pure perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films for the dehydration of nitric acid because of the speculation of improved water selectivity of the carboxylate pendant chain. During the first phase of these investigations the effort was focused on generating a thin, solution cast perfluoro carboxylate ionomer film, to evaluate the general, chemical and physical characteristics of the polymer, and to assess the material's aqueous transport performance (flux and nitrate separation efficiencies) in pervaporation and high-pressure environments. Results demonstrated that generating robust solution-cast films was difficult yet a number of membranes survived high trans-membrane pressures up to 700 psig. General characterization of the solution cast product showed reduced ion exchange capacities when compared with thicker, ''as received'' perfluoro carboxylate and similar sulfonate films. Small angle x-ray scattering analysis results suggested that the solution cast carboxylate films contained a small fraction of sulfonate terminated side-chains. Aqueous transport experimentation showed that permeate fluxes for both pure water and nitric acid were approximately two orders of magnitude smaller for the carboxylate solution cast membranes when compared to their sulfonate

  9. The activity of ascorbic acid and catechol oxidase, the rate of photosynthesis and respiration as related to plant organs, stage of development and copper supply

    Directory of Open Access Journals (Sweden)

    St. Łyszcz

    2015-06-01

    Full Text Available Some experiments were performed to investigate the physiological role of copper in oat and sunflower and to recognize some effects of copper deficiency. Oat and sunflower plants were grown in pots on a peat soil under copper deficiency conditions (–Cu or with the optimal copper supply (+Cu. In plants the following measurements were carried out: 1 the activity of ascorbic acid oxidase (AAO and of catechol oxidase (PPO in different plant organs and at different stages of plant development, 2 the activity and the rate of photosynthesis, 3 the activity of RuDP-carboxylase, 4 the intensity of plant respiration. The activity of AAO and of PPO, and also the rate and the activity of photosynthesis were significantly lower under conditions of copper deficiency. The activity of both discussed oxidases depended on: 1 the plant species, 2 plant organs, 3 stage of plant development. Copper deficiency caused decrease of the respiration intensity of sunflower leaves but it increased to some extent the respiration of oat tops. Obtained results are consistent with the earlier suggestion of the authors that the PPO activity in sunflower leaves could be a sensitive indicator of copper supply of the plants, farther experiments are in progress.

  10. Graft-crosslinked copolymers based on poly(arylene ether ketone)-gc-sulfonated poly(arylene ether sulfone) for PEMFC applications.

    Science.gov (United States)

    Zhang, Xuan; Hu, Zhaoxia; Luo, Linqiang; Chen, Shanshan; Liu, Jianmei; Chen, Shouwen; Wang, Lianjun

    2011-07-15

    Novel poly(arylene ether ketone) polymers with fluorophenyl pendants and phenoxide-terminated wholly sulfonated poly(arylene ether sulfone) oligomers are prepared via Ni(0)-catalyzed and nucleophilic polymerization, respectively, and subsequently used as starting materials to obtain graft-crosslinked membranes as polymer electrolyte membranes. The phenoxide-terminated sulfonated moieties are introduced as hydrophilic parts as well as crosslinking units. The chemical structure and morphology of the obtained membranes are confirmed by (1) H NMR and tapping-mode AFM. The properties required for fuel cell applications, including water uptake and dimensional change, as well as proton conductivity, are investigated. AFM results show a clear nanoscale phase-separation microstructure of the obtained membranes. The membranes show good dimensional stability and reasonably high proton conductivities under 30-90% relative humidity. The anisotropic proton conductivity ratios (σ(formula see text) ) of the membranes in water are in the range 0.65-0.92, and increase with an increase in hydrophilic block length. The results indicate that the graft-crosslinked membranes are promising candidates for applications as polymer electrolyte membranes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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.

  12. Patterning of electrically conductive poly(aniline-co-aniline sulfonic acid) and its application in the immobilization of cytochrome c

    International Nuclear Information System (INIS)

    Oh, Se Young; Oh, Il Soo; Choi, Jeong-Woo

    2004-01-01

    We have synthesized poly(aniline-co-aniline sulfonic acid) and then investigated the feasibility of application as a specific and electrically conductive binding template for biomolecules. Poly(aniline-co-aniline sulfonic acid)s were prepared by oxidation polymerization of aniline and aniline sulfonic acid under various ratios. A fine pattern of the conducting copolyaniline was obtained by using a deep UV lithographic technique. Cytochrome c was immobilized onto the photochemically patterned conducting copolyaniline with a self-assembly method. Physical and electrochemical properties of the self-assembled cytochrome c monolayer were studied from atomic force microscopy and cyclic voltammetry. The self-assembled cytochrome c monolayer immobilized onto the copolyaniline with a high electrical conductivity showed a high electrochemical activity

  13. 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.

  14. Alkyl phosphonic acids and sulfonic acids in the Murchison meteorite

    Science.gov (United States)

    Cooper, George W.; Onwo, Wilfred M.; Cronin, John R.

    1992-01-01

    Homologous series of alkyl phosphonic acids and alkyl sulfonic acids, along with inorganic orthophosphate and sulfate, are identified in water extracts of the Murchison meteorite after conversion to their t-butyl dimethylsilyl derivatives. The methyl, ethyl, propyl, and butyl compounds are observed in both series. Five of the eight possible alkyl phosphonic acids and seven of the eight possible alkyl sulfonic acids through C4 are identified. Abundances decrease with increasing carbon number as observed of other homologous series indigenous to Murchison. Concentrations range downward from approximately 380 nmol/gram in the alkyl sulfonic acid series, and from 9 nmol/gram in the alkyl phosphonic acid series.

  15. Characterization of Two VAO-Type Flavoprotein Oxidases from Myceliophthora thermophila

    Directory of Open Access Journals (Sweden)

    Alessandro R. Ferrari

    2018-01-01

    Full Text Available The VAO flavoprotein family consists mostly of oxidoreductases harboring a covalently linked flavin cofactor. The linkage can be either monocovalent at position 8 with a histidine or tyrosine or bicovalent at position 8 with a histidine and at position 6 with a cysteine. Bicovalently bound flavoproteins show a preference for bulkier substrates such as oligosaccharides or secondary metabolites. The genome of the thermophilic fungus Myceliophthora thermophila C1 was found to be rich in genes encoding putative covalent VAO-type flavoproteins. Enzymes from this fungus have the advantage of being rather thermostable and homologous overexpression in M. thermophila C1 is feasible. Recently we discovered a new and VAO-type carbohydrate oxidase from this fungus: xylooligosaccharide oxidase. In this study, two other putative VAO-type oxidases, protein sequence XP_003663615 (MtVAO615 and XP_003665713 (MtVAO713, were expressed in M. thermophila C1, purified and characterized. Enzyme MtVAO615 was found to contain a bicovalently bound FAD, while enzyme MtVAO713 contained a monocovalent histidyl-bound FAD. The crystal structures of both proteins were obtained which revealed atypical active site architectures. It could be experimentally verified that both proteins, when reduced, rapidly react with molecular oxygen, a hallmark of flavoprotein oxidases. A large panel of alcohols, including carbohydrates, steroids and secondary alcohols were tested as potential substrates. For enzyme MtVAO713 low oxidase activity was discovered towards ricinoleic acid.

  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. Poly (ether ether ketone) derivatives: Synthetic route and characterization of nitrated and sulfonated polymers

    International Nuclear Information System (INIS)

    Conceicao, T.F.; Bertolino, J.R.; Barra, G.M.O.; Pires, A.T.N.

    2009-01-01

    Nitrated and sulfonated poly (ether ether ketone) [SNPEEK] samples were prepared through sulfonation of nitrated PEEK (NPEEK) at different temperatures resulting in polymers with distinct sulfonation degrees (SD). The sulfonation occurred preferentially in the hydroquinone segment even after 81% of this moiety had been nitrated. Sulfonation in the benzophenone moiety was achieved only in 16% of this segment at the reaction temperature of 80 deg. C. The substitution degree was obtained through the TG curves, and values were in agreement with 1 H NMR data when SD is much higher as ND (nitration degree). The highest SD obtained was 72%. Membranes of the sulfonated and nitrated PEEK (SNPEEK) were prepared by casting and showed good ductility depending on the substitution degree, with proton conductivity in the order of 10 -2 S cm -1 , an important characteristic in some applications, such as in fuel cells

  18. Polymer sulfonation- a versatile route to prepare proton-conducting membrane material for advanced technologies

    International Nuclear Information System (INIS)

    Zaidi, S.M.J.

    2003-01-01

    Sulfonation of polymers is a viable method for making proton exchange membranes used in electrochemical devices. Polyether-ether ketone was modified by using concentrated sulfuric acid (97.4%) to produce ion-containing polymers bearing HSO3 groups. The sulfonated polymer was characterized for IEC, HNMR, DSC and water uptake etc. The degree of sulfonation of sulfonated PEEK was found to vary from 40 to 80 mol%. The PEEK became amorphous after sufonation (as evidenced from DSC and WXRD), which enhanced its solubility in organic solvents such as DMF. The glass transition temperature, Tg increased from 151C for pure PEEK to 217C upon sulfonation. The water uptake was also increased with sulfonation level, which provides formation of water-mediated pathways for protons involving SO3H groups. The membranes from these polymers have a high potential for use in electrochemical devices such as polymer fuel cell and electrodialysis. (author)

  19. Poly (ether ether ketone) derivatives: Synthetic route and characterization of nitrated and sulfonated polymers

    Energy Technology Data Exchange (ETDEWEB)

    Conceicao, T.F.; Bertolino, J.R. [Grupo de Estudo em Materiais Polimericos-Departamento de Quimica, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil); Barra, G.M.O. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil); Pires, A.T.N. [Grupo de Estudo em Materiais Polimericos-Departamento de Quimica, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil)], E-mail: alfredotiburcio@pq.cnpq.br

    2009-03-01

    Nitrated and sulfonated poly (ether ether ketone) [SNPEEK] samples were prepared through sulfonation of nitrated PEEK (NPEEK) at different temperatures resulting in polymers with distinct sulfonation degrees (SD). The sulfonation occurred preferentially in the hydroquinone segment even after 81% of this moiety had been nitrated. Sulfonation in the benzophenone moiety was achieved only in 16% of this segment at the reaction temperature of 80 deg. C. The substitution degree was obtained through the TG curves, and values were in agreement with {sup 1}H NMR data when SD is much higher as ND (nitration degree). The highest SD obtained was 72%. Membranes of the sulfonated and nitrated PEEK (SNPEEK) were prepared by casting and showed good ductility depending on the substitution degree, with proton conductivity in the order of 10{sup -2} S cm{sup -1}, an important characteristic in some applications, such as in fuel cells.

  20. Identification and statistical optimization of fermentation conditions for a newly isolated extracellular cholesterol oxidase-producing Streptomyces cavourensis strain NEAE-42

    OpenAIRE

    El-Naggar, Noura El-Ahmady; El-Shweihy, Nancy M.; El-Ewasy, Sara M.

    2016-01-01

    Background Due to broad range of clinical and industrial applications of cholesterol oxidase, isolation and screening of bacterial strains producing extracellular form of cholesterol oxidase is of great importance. Results One hundred and thirty actinomycete isolates were screened for their cholesterol oxidase activity. Among them, a potential culture, strain NEAE-42 is displayed the highest extracellular cholesterol oxidase activity. It was selected and identified as Streptomyces cavourensis...

  1. In vitro antioxidant, lipoxygenase and xanthine oxidase inhibitory activities of fractions from Cienfuegosia digitata Cav., Sida alba L. and Sida acuta Burn f. (Malvaceae).

    Science.gov (United States)

    Konaté, K; Souza, A; Coulibaly, A Y; Meda, N T R; Kiendrebeogo, M; Lamien-Meda, A; Millogo-Rasolodimby, J; Lamidi, M; Nacoulma, O G

    2010-11-15

    In this study polyphenol content, antioxidant activity, lipoxygenase (LOX) and Xanthine Oxidase (XO) inhibitory effects of n-hexane, dichloromethane, ethyl acetate and n-butanol fractions of aqueous acetone extracts from S. alba L., S. acuta Burn f and Cienfuegosia digitata Cav. were investigated. The total phenolics, flavonoids, flavonols and total tannins were determined by spectrophotometric methods using Folin-ciocalteu, AlCl3 reagents and tannic acid, respectively. The antioxidant potential was evaluated using three methods: inhibition of free radical 2,2-diphenyl-1-picrylhydramzyl (DPPH), ABTS radical cation decolorization assay and Iron (III) to iron (II) reduction activity (FRAP). For enzymatic activity, lipoxygenase and xanthine oxidase inhibitory activities were used. This study shows a relationship between polyphenol contents, antioxidant and enzymatic activities. Present results showed that ethyl acetate and dichloromethane fractions elicit the highest polyphenol content, antioxidant and enzymatic activities.

  2. Inhibition of S-adenosylmethionine decarboxylase and diamine oxidase activities by analogues of methylglyoxal bis(guanylhydrazone) and their cellular uptake during lymphocyte activation.

    OpenAIRE

    Jänne, J; Morris, D R

    1984-01-01

    Several congeners of methylglyoxal bis(guanylhydrazone) were tested for their ability to inhibit eukaryotic putrescine-activated S-adenosylmethionine decarboxylase (EC 4.1.1.50) and intestinal diamine oxidase (EC 1.4.3.6). All the compounds tested, namely methylglyoxal bis(guanylhydrazone), ethylglyoxal bis(guanylhydrazone), dimethylglyoxal bis(guanylhydrazone) and the di-N"-methyl derivative of methylglyoxal bis(guanylhydrazone), were strong inhibitors of both yeast and mouse liver adenosylm...

  3. Cytochrome oxidase as an indicator of ice storage and frozen storage

    DEFF Research Database (Denmark)

    Godiksen, Helene; Jessen, Flemming

    2001-01-01

    in different cods was 21%, and the coefficient of variation of different analyses on the same homogenate was 5%. It was shown that ice storage of muscle samples before they were frozen and thawed resulted in a major freezing-induced activation of cytochrome oxidase activity. The enzyme may therefore be used...... as an indicator of frozen fish to determine if the fish has been stored on ice before freezing. Cytochrome oxidase activity showed also potential as an indicator of frozen storage, as it was possible to distinguish between the frozen storage temperatures -9, -20, and -40 degreesC....

  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. 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

  6. NADPH oxidase/ROS-dependent PYK2 activation is involved in TNF-α-induced matrix metalloproteinase-9 expression in rat heart-derived H9c2 cells

    International Nuclear Information System (INIS)

    Yang, Chuen-Mao; Lee, I-Ta; Hsu, Ru-Chun; Chi, Pei-Ling; Hsiao, Li-Der

    2013-01-01

    TNF-α plays a mediator role in the pathogenesis of chronic heart failure contributing to cardiac remodeling and peripheral vascular disturbances. The implication of TNF-α in inflammatory responses has been shown to be mediated through up-regulation of matrix metalloproteinase-9 (MMP-9). However, the detailed mechanisms of TNF-α-induced MMP-9 expression in rat embryonic-heart derived H9c2 cells are largely not defined. We demonstrated that in H9c2 cells, TNF-α induced MMP-9 mRNA and protein expression associated with an increase in the secretion of pro-MMP-9. TNF-α-mediated responses were attenuated by pretreatment with the inhibitor of ROS (N-acetyl-L-cysteine, NAC), NADPH oxidase [apocynin (APO) or diphenyleneiodonium chloride (DPI)], MEK1/2 (U0126), p38 MAPK (SB202190), JNK1/2 (SP600125), NF-κB (Bay11-7082), or PYK2 (PF-431396) and transfection with siRNA of TNFR1, p47 phox , p42, p38, JNK1, p65, or PYK2. Moreover, TNF-α markedly induced NADPH oxidase-derived ROS generation in these cells. TNF-α-enhanced p42/p44 MAPK, p38 MAPK, JNK1/2, and NF-κB (p65) phosphorylation and in vivo binding of p65 to the MMP-9 promoter were inhibited by U0126, SB202190, SP600125, NAC, DPI, or APO. In addition, TNF-α-mediated PYK2 phosphorylation was inhibited by NAC, DPI, or APO. PYK2 inhibition could reduce TNF-α-stimulated MAPKs and NF-κB activation. Thus, in H9c2 cells, we are the first to show that TNF-α-induced MMP-9 expression is mediated through a TNFR1/NADPH oxidase/ROS/PYK2/MAPKs/NF-κB cascade. We demonstrated that NADPH oxidase-derived ROS generation is involved in TNF-α-induced PYK2 activation in these cells. Understanding the regulation of MMP-9 expression and NADPH oxidase activation by TNF-α on H9c2 cells may provide potential therapeutic targets of chronic heart failure. - Highlights: • TNF-α induces MMP-9 secretion and expression via a TNFR1-dependent pathway. • TNF-α induces ROS/PYK2-dependent MMP-9 expression in H9c2 cells. • TNF-α induces

  7. 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.

  8. A Xylenol Orange-Based Screening Assay for the Substrate Specificity of Flavin-Dependent para-Phenol Oxidases

    Directory of Open Access Journals (Sweden)

    Tom A. Ewing

    2018-01-01

    Full Text Available Vanillyl alcohol oxidase (VAO and eugenol oxidase (EUGO are flavin-dependent enzymes that catalyse the oxidation of para-substituted phenols. This makes them potentially interesting biocatalysts for the conversion of lignin-derived aromatic monomers to value-added compounds. To facilitate their biocatalytic exploitation, it is important to develop methods by which variants of the enzymes can be rapidly screened for increased activity towards substrates of interest. Here, we present the development of a screening assay for the substrate specificity of para-phenol oxidases based on the detection of hydrogen peroxide using the ferric-xylenol orange complex method. The assay was used to screen the activity of VAO and EUGO towards a set of twenty-four potential substrates. This led to the identification of 4-cyclopentylphenol as a new substrate of VAO and EUGO and 4-cyclohexylphenol as a new substrate of VAO. Screening of a small library of VAO and EUGO active-site variants for alterations in their substrate specificity led to the identification of a VAO variant (T457Q with increased activity towards vanillyl alcohol (4-hydroxy-3-methoxybenzyl alcohol and a EUGO variant (V436I with increased activity towards chavicol (4-allylphenol and 4-cyclopentylphenol. This assay provides a quick and efficient method to screen the substrate specificity of para-phenol oxidases, facilitating the enzyme engineering of known para-phenol oxidases and the evaluation of the substrate specificity of novel para-phenol oxidases.

  9. A Xylenol Orange-Based Screening Assay for the Substrate Specificity of Flavin-Dependent para-Phenol Oxidases.

    Science.gov (United States)

    Ewing, Tom A; van Noord, Aster; Paul, Caroline E; van Berkel, Willem J H

    2018-01-14

    Vanillyl alcohol oxidase (VAO) and eugenol oxidase (EUGO) are flavin-dependent enzymes that catalyse the oxidation of para -substituted phenols. This makes them potentially interesting biocatalysts for the conversion of lignin-derived aromatic monomers to value-added compounds. To facilitate their biocatalytic exploitation, it is important to develop methods by which variants of the enzymes can be rapidly screened for increased activity towards substrates of interest. Here, we present the development of a screening assay for the substrate specificity of para -phenol oxidases based on the detection of hydrogen peroxide using the ferric-xylenol orange complex method. The assay was used to screen the activity of VAO and EUGO towards a set of twenty-four potential substrates. This led to the identification of 4-cyclopentylphenol as a new substrate of VAO and EUGO and 4-cyclohexylphenol as a new substrate of VAO. Screening of a small library of VAO and EUGO active-site variants for alterations in their substrate specificity led to the identification of a VAO variant (T457Q) with increased activity towards vanillyl alcohol (4-hydroxy-3-methoxybenzyl alcohol) and a EUGO variant (V436I) with increased activity towards chavicol (4-allylphenol) and 4-cyclopentylphenol. This assay provides a quick and efficient method to screen the substrate specificity of para -phenol oxidases, facilitating the enzyme engineering of known para- phenol oxidases and the evaluation of the substrate specificity of novel para -phenol oxidases.

  10. 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.

  11. Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen

    Energy Technology Data Exchange (ETDEWEB)

    Pasqualini, Stefania, E-mail: spas@unipg.it [Department of Applied Biology, University of Perugia, Perugia (Italy); Tedeschini, Emma; Frenguelli, Giuseppe [Department of Applied Biology, University of Perugia, Perugia (Italy); Wopfner, Nicole; Ferreira, Fatima [Department of Molecular Biology, CD Laboratory for Allergy Diagnosis and Therapy, University of Salzburg, Salzburg (Austria); D' Amato, Gennaro [Division of Respiratory and Allergic Diseases, ' A. Cardarelli' High Speciality Hospital, Naples (Italy); Ederli, Luisa [Department of Applied Biology, University of Perugia, Perugia (Italy)

    2011-10-15

    Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O{sub 3}) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O{sub 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{sub 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{sub 3}, determined from the mRNA levels of the major allergens. We conclude that O{sub 3} can increase ragweed pollen allergenicity through stimulation of ROS-generating NAD(P)H oxidase. - Highlights: > O{sub 3} reduces the viability of ragweed pollen. > ROS and allergens of ragweed pollen were not affected by O{sub 3} exposure. > O{sub 3} enhances the activity of the ROS-generating enzyme NAD(P)H oxidase. > O{sub 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.

  12. On the Importance of Purification of Sodium Polystyrene Sulfonate

    OpenAIRE

    Sen, Akhil K.; Roy, Sandip; Juvekar, Vinay A.

    2012-01-01

    Ion exchange is commonly employed for purification of sodium polystyrene sulfonate (NaPSS), a molecule widely used as a model polyelectrolyte. However, the present work demonstrates that the ion exchange process itself may introduce some extraneous species into NaPSS samples by two possible mechanisms: (i) chemical transformation of polystyrene sulfonic acid (HPSS), a relatively unstable intermediate formed during ion exchange and (ii) release of small amount of “condensed” acid from cationic...

  13. 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

  14. Synthesis and properties of a novel sulfonated poly(arylene ether ketone sulfone) membrane with a high β-value for direct methanol fuel cell applications

    International Nuclear Information System (INIS)

    Xu, Jingmei; Ma, Li; Han, Hailan; Ni, Hongzhe; Wang, Zhe; Zhang, Huixuan

    2014-01-01

    Highlights: • Introduction of carboxyl groups into copolymers resulted in extensive hydrogen bond. • The C-SPAEKS membranes had obviously hydrophilic/hydrophobic phase separation. • The membranes showed low methanol permeability and high β values. • The membranes exhibited good thermal property and desirable mechanical performance. - Abstract: Sulfonated poly(arylene ether ketone sulfone) membranes containing carboxylic acid groups (C-SPAEKS) with different degrees of sulfonation were synthesized by the nucleophilic aromatic substitution reactions of 4-carboxylphenyl hydroquinone (4C-PH), bisphenol A, 3,3′-disulfonated 4,4′-dichlorodiphenyl sulfone, and 4,4′-difluorobenzophenone. The Fourier transform infrared and 1 H NMR analyses of C-SPAEKS revealed the presence of carboxylic acid groups in the C-SPAEKS membranes. The membranes exhibited a low swelling degree and methanol crossover level. The effects of different degrees of sulfonation on the water uptake, proton conductivity, and methanol permeability coefficient of the membranes were studied. The maximum proton conductivity of C-SPAEKS-80 membrane at room temperature was 0.069 S cm −1 , which was higher than that of Nafion ® 117 membrane. The methanol permeability coefficient of C-SPAEKS-80 membrane was 9.15 × 10 −7 cm 2 s −1 at 20 °C, much lower than that of Nafion 117 membrane (22.9 × 10 −7 cm 2 s −1 ). Furthermore, the carboxyl group-containing membranes exhibited a high β-value, further confirming that this series of membranes possess excellent comprehensive performance and can be applied in direct methanol fuel cells

  15. Sulfonation and characterization of styrene-indene copolymers for the development of proton conducting polymer membranes

    Directory of Open Access Journals (Sweden)

    Cristiane M. Becker

    2012-01-01

    Full Text Available The aim of this work is to obtain polymer precursors based on styrene copolymers with distinct degrees of sulfonation, as an alternative material for fuel cell membranes. Acetyl sulfate was used to carry out the sulfonation and the performance of the polyelectrolyte was evaluated based on the content of acid polar groups incorporated into the macromolecular chain. Polymeric films were produced by blending the sulfonated styrene-indene copolymer with poly(vinylidene fluoride. The degree of sulfonation of the polymer was strongly affected by the sulfonation reaction parameters, with a direct impact on the ionic exchange capacity and the ionic conductivity of the sulfonated polymers and the membranes obtained from them. The films produced with the blends showed more suitable mechanical properties, although the conductivity of the membranes was still lower than that of commercially available membranes used in fuel cells.

  16. Immunological and molecular comparison of polyphenol oxidase in Rosaceae fruit trees.

    Science.gov (United States)

    Haruta, M; Murata, M; Kadokura, H; Homma, S

    1999-03-01

    An antibody raised against apple polyphenol oxidase (PPO) cross-reacted with PPOs from Japanese pear (Pyrus pyrifolia), pear (Pyrus communis), peach (Prunus persica), Chinese quince (Pseudocydonia sinensis) and Japanese loquat (Eriobotrya japonica). Core fragments (681 bp) of the corresponding PPO genes were amplified and characterized. The deduced protein sequences showed identities of 85.3 to 97.5%. Chlorogenic acid oxidase activity of these PPOs showed higher activities when assayed at pH 4 than at pH 6. These results indicate that PPOs in Rosaceae plants are structurally and enzymatically similar.

  17. Effect of gamma irradiation on the activity of monoamine oxidase in the hypothalamus of ewes

    International Nuclear Information System (INIS)

    Pastorova, B.; Stanikova, A.

    2008-01-01

    The study investigated changes in monoamine oxidase (MAO) activity in the hypothalamus of ewes in the anoestrous period exposed to a whole body Co-60 irradiation with a total dose of 6.7 Gy for the period of 7 days. The activity of MAO was determined by means of a radiochemical method using C-14 tryptamine as a substrate. Whole body exposure to gamma radiation of total dose of 6.7 Gy increased significantly (P < 0.001) the activity of MAO in the caudal, medial and rostral hypothalamus of the investigated ewes. It may by assumed that an increased degradation of catecholamines caused by MAO is one of the mechanisms responsible for pronounced changes in the level of catecholamines in the hypothalamus of ewes after irradiation. (authors)

  18. 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.

  19. 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...

  20. 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

  1. Expression of novel rice gibberellin 2-oxidase gene is under homeostatic regulation by biologically active gibberellins.

    Science.gov (United States)

    Sakai, Miho; Sakamoto, Tomoaki; Saito, Tamio; Matsuoka, Makoto; Tanaka, Hiroshi; Kobayashi, Masatomo

    2003-04-01

    We have cloned two genes for gibberellin (GA) 2-oxidase from rice ( Oryza sativa L.). Expression of OsGA2ox2 was not observed. The other gene, OsGA2ox3, was expressed in every tissue examined and was enhanced by the application of biologically active GA. Recombinant OsGA2ox3 protein catalyzed the metabolism of GA(1) to GA(8) and GA(20) to GA(29)-catabolite. These results indicate that OsGA2ox3 is involved in the homeostatic regulation of the endogenous level of biologically active GA in rice.

  2. Inhibition of the anaerobic digestion process by linear alkylbenzene sulfonates

    DEFF Research Database (Denmark)

    Gavala, Hariklia N.; Ahring, Birgitte Kiær

    2002-01-01

    Linear Alkylbenzene Sulfonates (LAS) are the most widely used synthetic anionic surfactants. They are anthropogenic, toxic compounds and are found in the primary sludge generated in municipal wastewater treatment plants. Primary sludge is usually stabilized anaerobically and therefore it is impor......Linear Alkylbenzene Sulfonates (LAS) are the most widely used synthetic anionic surfactants. They are anthropogenic, toxic compounds and are found in the primary sludge generated in municipal wastewater treatment plants. Primary sludge is usually stabilized anaerobically and therefore...... it is important to investigate the effect of these xenobiotic compounds on an anaerobic environment. The inhibitory effect of Linear Alkylbenzene Sulfonates (LAS) on the acetogenic and methanogenic step of the anaerobic digestion process was studied. LAS inhibit both acetogenesis from propionate...

  3. Copolymers of fluorinated polydienes and sulfonated polystyrene

    Science.gov (United States)

    Mays, Jimmy W [Knoxville, TN; Gido, Samuel P [Hadley, MA; Huang, Tianzi [Knoxville, TN; Hong, Kunlun [Knoxville, TN

    2009-11-17

    Copolymers of fluorinated polydienes and sulfonated polystyrene and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization.

  4. Blocking Surgically Induced Lysyl Oxidase Activity Reduces the Risk of Lung Metastases

    Directory of Open Access Journals (Sweden)

    Chen Rachman-Tzemah

    2017-04-01

    Full Text Available Surgery remains the most successful curative treatment for cancer. However, some patients with early-stage disease who undergo surgery eventually succumb to distant metastasis. Here, we show that in response to surgery, the lungs become more vulnerable to metastasis due to extracellular matrix remodeling. Mice that undergo surgery or that are preconditioned with plasma from donor mice that underwent surgery succumb to lung metastases earlier than controls. Increased lysyl oxidase (LOX activity and expression, fibrillary collagen crosslinking, and focal adhesion signaling contribute to this effect, with the hypoxic surgical site serving as the source of LOX. Furthermore, the lungs of recipient mice injected with plasma from post-surgical colorectal cancer patients are more prone to metastatic seeding than mice injected with baseline plasma. Downregulation of LOX activity or levels reduces lung metastasis after surgery and increases survival, highlighting the potential of LOX inhibition in reducing the risk of metastasis following surgery.

  5. 40 CFR 417.110 - Applicability; description of the SO3 solvent and vacuum sulfonation subcategory.

    Science.gov (United States)

    2010-07-01

    ... solvent and vacuum sulfonation subcategory. 417.110 Section 417.110 Protection of Environment... POINT SOURCE CATEGORY SO3 Solvent and Vacuum Sulfonation Subcategory § 417.110 Applicability; description of the SO3 solvent and vacuum sulfonation subcategory. The provisions of this subpart are...

  6. 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 ...

  7. Design, synthesis, and characterization of lightly sulfonated multigraft acrylate-based copolymer superelastomers

    Energy Technology Data Exchange (ETDEWEB)

    Misichronis, Konstantinos [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division; Wang, Weiyu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Cheng, Shiwang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division; Wang, Yangyang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Shrestha, Umesh [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Dadmun, Mark D. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division; Mays, Jimmy W. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division; Saito, Tomonori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division

    2018-01-29

    Multigraft copolymer superelastomers consisting of a poly(n-butyl acrylate) backbone and polystyrene side chains were synthesized and the viscoelastic properties of the non-sulfonated and sulfonated final materials were investigated using extensional rheology (SER3). The non-linear viscoelastic experiments revealed significantly increased true stresses (up to 10 times higher) after sulfonating only 2–3% of the copolymer while the materials maintained high elongation (<700%). The linear viscoelastic experiments showed that the storage and loss modulus are increased by sulfonation and that the copolymers can be readily tuned and further improved by increasing the number of branching points and the molecular weight of the backbone. Here, in this way, we show that by tuning not only the molecular characteristics of the multigraft copolymers but also their architecture and chemical interaction, we can acquire thermoplastic superelastomer materials with desired viscoelastic properties.

  8. Fe–Co/sulfonated polystyrene as an efficient and selective catalyst in heterogeneous Baeyer–Villiger oxidation reaction of cyclic ketones

    Directory of Open Access Journals (Sweden)

    Yingting Wang

    2018-02-01

    Full Text Available A highly efficient catalyst Fe–Co/sulfonated polystyrene (Fe–Co/SPS was introduced and synthesized, which catalyzed BV oxidation of ketones with aqueous hydrogen peroxide to give the corresponding lactones in high yield and selectivity. Solid acid catalyst of Fe–Co/SPS has been prepared by using the 98-wt% sulfuric acid as the sulfonating agent and CoCl2 combined FeCl3 as sources of metal ions. Various physical–chemical characterizations including FT-IR, XRD, SEM and TGA, revealed that bimetallic ions Fe3+–Co2+ species in the sulfonated polystyrene framework were responsible for the catalytic activities. The BV reaction catalyzed by Fe–Co/SPS highlighted the special effects between metal ions and protonic acids as well as solvent-free heterogeneous catalytic oxidation with excellent conversion.

  9. Sulfonated polyimides containing triphenylphosphine oxide for proton exchange membranes

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Arun Kumar; Bera, Debaditya; Banerjee, Susanta, E-mail: susanta@matsc.iitkgp.ernet.in

    2016-09-15

    A series of sulfonated co-polyimides (co-SPI) were prepared by one pot polycondensation reaction of a combination of diamines namely; 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA) and prepared non-sulfonated diamine (DATPPO) containing triphenylphosphine oxide with 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). All these soluble co-SPI gave flexible membranes with high thermal stability and showed good mechanical property. Transmission electron microscopy (TEM) analysis revealed the microphase separated morphology with well-dispersed hydrophilic (cluster size in the range of 5–55 nm) domains. The co-SPI membranes showed high oxidative and hydrolytic stability with higher proton conductivity. All these co-SPI membranes exhibited low water uptake and swelling ratio. The co-SPI membrane TPPO-60 (60% degree of sulfonation) with IEC{sub W} = 1.84 mequiv g{sup −1} showed high proton conductivity (99 mS cm{sup −1} at 80 °C and 107 mS cm{sup −1} at 90 °C) in water with high oxidative (20 h) and hydrolytic stability (only 5% degradation in 24 h). - Highlights: • Triphenylphosphine oxide containing sulfonated polyimides (SPIs) was synthesized. • The SPIs showed good oxidative and hydrolytic stability and high proton conductivity. • TEM analysis revealed well separated morphology of the SPIs.

  10. Methadone, monoamine oxidase, and depression: opioid distribution and acute effects on enzyme activity

    International Nuclear Information System (INIS)

    Kaufmann, C.A.; Kreek, M.J.; Raghunath, J.; Arns, P.

    1983-01-01

    Narcotic withdrawal is often accompanied by an atypical depression which responds to resumption of narcotics. It was hypothesized that methadone might exert its antidepressant effects through monoamine oxidase (MAO) inhibition. The current study examined 3 H-methadone distribution in rat brain and effects on regional MAO activity with acute doses (2.5 mg/kg) which approximate those found during chronic methadone maintenance in man. Limbic areas (amygdala, basomedial hypothalamus, caudate-putamen, hippocampus, preoptic nucleus), as well as pituitary and liver were assayed for MAO activity and methadone concentration. MAO activities did not differ significantly in acute methadone or saline-treated cage-mates at 1 or 24 hr. The concentrations of methadone at 1 hr ranged between 17 and 223 ng/100 mg wet wt tissue in the preoptic nucleus and pituitary, respectively. No significant correlation was found between change in MAO activity (MAO methadone/MAO saline) and methadone concentration in any region at 1 or 24 hr. This study does not support the hypothesis that methadone acts as an antidepressant through MAO inhibition, at least not following acute administration of this exogenous opioid

  11. Chemical mechanical polishing of hard disk substrate with {alpha}-alumina-g-polystyrene sulfonic acid composite abrasive

    Energy Technology Data Exchange (ETDEWEB)

    Lei Hong, E-mail: hong_lei2005@yahoo.com.c [Research Center of Nano-science and Nano-technology, Shanghai University, Shanghai 200444 (China); Bu Naijing; Chen Ruling; Hao Ping [Research Center of Nano-science and Nano-technology, Shanghai University, Shanghai 200444 (China); Neng Sima; Tu Xifu; Yuen Kwok [Shenzhen Kaifa Magnetic Recording Co., LTD, Shenzhen, 518035 (China)

    2010-05-03

    {alpha}-Alumina-g-polystyrene sulfonic acid ({alpha}-Al{sub 2}O{sub 3}-g-PSS) composite abrasive was prepared by surface activation, graft polymerization and sulfonation, successively. The composition, dispersibility and morphology of the product were characterized by Fourier transformed infrared spectroscopy, laser particle size analysis and scanning electron microscopy, respectively. The chemical mechanical polishing (CMP) performances of the composite abrasive on hard disk substrate with nickel-phosphorous plating were investigated. The microscopy images of the polished surfaces show that {alpha}-Al{sub 2}O{sub 3}-g-PSS composite abrasive results in improved CMP and post-CMP cleaning performances than pure {alpha}-alumina abrasive under the same testing conditions.

  12. Inhibition of chrysin on xanthine oxidase activity and its inhibition mechanism.

    Science.gov (United States)

    Lin, Suyun; Zhang, Guowen; Liao, Yijing; Pan, Junhui

    2015-11-01

    Chrysin, a bioactive flavonoid, was investigated for its potential to inhibit the activity of xanthine oxidase (XO), a key enzyme catalyzing xanthine to uric acid and finally causing gout. The kinetic analysis showed that chrysin possessed a strong inhibition on XO ability in a reversible competitive manner with IC50 value of (1.26±0.04)×10(-6)molL(-1). The results of fluorescence titrations indicated that chrysin bound to XO with high affinity, and the interaction was predominately driven by hydrogen bonds and van der Waals forces. Analysis of circular dichroism demonstrated that chrysin induced the conformational change of XO with increases in α-helix and β-sheet and reductions in β-turn and random coil structures. Molecular simulation revealed that chrysin interacted with the amino acid residues Leu648, Phe649, Glu802, Leu873, Ser876, Glu879, Arg880, Phe1009, Thr1010, Val1011 and Phe1013 located within the active cavity of XO. The mechanism of chrysin on XO activity may be the insertion of chrysin into the active site occupying the catalytic center of XO to avoid the entrance of xanthine and causing conformational changes in XO. Furthermore, the interaction assays indicated that chrysin and its structural analog apigenin exhibited an additive effect on inhibition of XO. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Two-step sulfonation process for the conversion of polymer fibers to carbon fibers

    Science.gov (United States)

    Barton, Bryan E.; Patton, Jasson T.; Hukkanen, Eric J.; Bernius, Mark T.

    2017-11-14

    Disclosed herein are processes for preparing carbon fibers, comprising: sulfonating a polymer fiber with a sulfonating agent that is fuming sulfuric acid, sulfuric acid, chlorosulfonic acid, or a combination thereof; treating the sulfonated polymer with a heated solvent, wherein the temperature of the heated solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 501-3000.degree. C. Carbon fibers prepared according to these methods are also disclosed herein.

  14. 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.

  15. A benzoxazine derivative induces vascular endothelial cell apoptosis in the presence of fibroblast growth factor-2 by elevating NADPH oxidase activity and reactive oxygen species levels.

    Science.gov (United States)

    Zhao, Jing; He, Qiuxia; Cheng, Yizhe; Zhao, Baoxiang; Zhang, Yun; Zhang, Shangli; Miao, Junying

    2009-09-01

    Previously, we found that 6,8-dichloro-2,3-dihydro-3-hydroxymethyl-1,4-benzoxazine (DBO) promoted apoptosis of human umbilical vascular endothelial cells (HUVECs) deprived of growth factors. In this study, we aimed to investigate the effect of DBO and its mechanism of action on angiogenesis and apoptosis of HUVECs in the presence of fibroblast growth factor-2 (FGF-2), which promotes angiogenesis and inhibits apoptosis in vivo and in vitro. DBO significantly inhibited capillary-like tube formation by promoting apoptosis of HUVECs in the presence of FGF-2 in vitro. Furthermore, DBO elevated the levels of reactive oxygen species (ROS) and nitric oxide (NO) and increased the activity of NADPH oxidase and inducible nitric oxide synthase (iNOS) in promoting apoptosis under this condition. Moreover, when NADPH oxidase was inhibited by its specific inhibitor, dibenziodolium chloride (DPI), DBO could not elevate ROS and NO levels in HUVECs. The data suggest that DBO is a new modulator of apoptosis in vitro, and it might function by increasing the activity of NADPH oxidase and iNOS, subsequently elevating the levels of ROS and NO in HUVECs. The findings of this study provide a new small molecule for investigating the FGF-2/NADPH oxidase/iNOS signaling pathway in apoptosis.

  16. Potential contact and intraocular lenses based on hydrophilic/hydrophobic sulfonated syndiotactic polystyrene membranes

    Directory of Open Access Journals (Sweden)

    Simona Zuppolini

    2017-10-01

    Full Text Available Crystalline films of syndiotactic polystyrene (s-PS, a commercially available thermoplastic polymer, having a highly hydrophilic amorphous phase, were achieved by using a mild solid-state sulfonation procedure. Despite the used mild process conditions, an easy and uniform sulfonation of the phenyl rings of the amorphous phase is obtained. The crystallinity of the polymer was not affect by the sulfonation degree (S, at least at S less than 20%, and the obtained polymer films show the nanoporous crystalline form of s-PS. As widely reported in literature, the nanoporous nature of the polymer crystalline phase gives to these materials the ability to absorb and release organic molecules of appropriate size and polarity. This property, coupled to transparency, makes these materials potentially useful intraocular lens (IOLs and contact lens applications. Sulfonation procedure and sulfonated film samples characterization by using wide-angle X-ray diffraction (WAXD, Fourier-transform infrared (FTIR and ultraviolet-visible (UV-vis spectroscopy techniques and water sorption tests were reported. Furthermore, the biocompatibility study demonstrated no cytotoxicity and appropriate cell interaction properties for the specific applications.

  17. 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.

  18. Dietary Phenolic Compounds Interfere with the Fate of Hydrogen Peroxide in Human Adipose Tissue but Do Not Directly Inhibit Primary Amine Oxidase Activity

    Directory of Open Access Journals (Sweden)

    Christian Carpéné

    2016-01-01

    Full Text Available Resveratrol has been reported to inhibit monoamine oxidases (MAO. Many substrates or inhibitors of neuronal MAO interact also with other amine oxidases (AO in peripheral organs, such as semicarbazide-sensitive AO (SSAO, known as primary amine oxidase, absent in neurones, but abundant in adipocytes. We asked whether phenolic compounds (resveratrol, pterostilbene, quercetin, and caffeic acid behave as MAO and SSAO inhibitors. AO activity was determined in human adipose tissue. Computational docking and glucose uptake assays were performed in 3D models of human AO proteins and in adipocytes, respectively. Phenolic compounds fully inhibited the fluorescent detection of H2O2 generated during MAO and SSAO activation by tyramine and benzylamine. They also quenched H2O2-induced fluorescence in absence of biological material and were unable to abolish the oxidation of radiolabelled tyramine and benzylamine. Thus, phenolic compounds hampered H2O2 detection but did not block AO activity. Only resveratrol and quercetin partially impaired MAO-dependent [14C]-tyramine oxidation and behaved as MAO inhibitors. Phenolic compounds counteracted the H2O2-dependent benzylamine-stimulated glucose transport. This indicates that various phenolic compounds block downstream effects of H2O2 produced by biogenic or exogenous amine oxidation without directly inhibiting AO. Phenolic compounds remain of interest regarding their capacity to limit oxidative stress rather than inhibiting AO.

  19. Novel high-performance nanocomposite proton exchange membranes based on poly (ether sulfone)

    Energy Technology Data Exchange (ETDEWEB)

    Hasani-Sadrabadi, Mohammad Mahdi [Polymer Engineering Department, Amirkabir University of Technology, Tehran (Iran); Biomedical Engineering Department, Amirkabir University of Technology, Tehran (Iran); Dashtimoghadam, Erfan; Ghaffarian, Seyed Reza [Polymer Engineering Department, Amirkabir University of Technology, Tehran (Iran); Hasani Sadrabadi, Mohammad Hossein [Faculty of Social and Economics Science, Alzahra University, Tehran (Iran); Heidari, Mahdi [Graduate School of Management and Economics, Sharif University of Technology, Tehran (Iran); Moaddel, Homayoun [Department of Materials Science and Engineering, University of California, Los Angeles, CA (United States)

    2010-01-15

    In the present research, proton exchange membranes based on partially sulfonated poly (ether sulfone) (S-PES) with various degrees of sulfonation were synthesized. It was found that the increasing of sulfonation degree up to 40% results in the enhancement of water uptake, ion exchange capacity and proton conductivity properties of the prepared membranes to 28.1%, 1.59 meq g{sup -1}, and 0.145 S cm{sup -1}, respectively. Afterwards, nanocomposite membranes based on S-PES (at the predetermined optimum sulfonation degree) containing various loading weights of organically treated montmorillonite (OMMT) were prepared via the solution intercalation technique. X-ray diffraction patterns revealed the exfoliated structure of OMMT in the macromolecular matrices. The S-PES nanocomposite membrane with 3.0 wt% of OMMT content showed the maximum selectivity parameter of about 520,000 S s cm{sup -3} which is related to the high conductivity of 0.051 S cm{sup -1} and low methanol permeability of 9.8 x 10{sup -8} cm{sup 2} s{sup -1}. Furthermore, single cell DMFC fuel cell performance test with 4 molar methanol concentration showed a high power density (131 mW cm{sup -2}) of the nanocomposite membrane at the optimum composition (40% of sulfonation and 3.0 wt% of OMMT loading) compared to the Nafion {sup registered} 117 membrane (114 mW cm{sup -2}). Manufactured nanocomposite membranes thanks to their high selectivity, ease of preparation and low cost could be suggested as the ideal candidate for the direct methanol fuel cell applications. (author)

  20. 40 CFR 721.2565 - Alkylated sulfonated diphenyl oxide, alkali and amine salts.

    Science.gov (United States)

    2010-07-01

    ..., alkali and amine salts. 721.2565 Section 721.2565 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.2565 Alkylated sulfonated diphenyl oxide, alkali and... substances identified as alkylated sulfonated diphenyl oxide, alkali salt (PMN P-93-352) and alkylated...

  1. Role of catechins on ET-1 induced stimulation of PLD and NADPH oxidase activities in pulmonary smooth muscle cells: Determination of the probable mechanism by molecular docking studies.

    Science.gov (United States)

    Chakraborti, Sajal; Sarkar, Jaganmay; Bhuyan, Rajabrata; Chakraborti, Tapati

    2017-12-05

    Treatment of human pulmonary artery smooth muscle cells with ET-1 stimulated PLD and NADPH oxidase activities, which were inhibited upon pretreatment with bosentan (ET-1 receptor antagonist), FIPI (PLD inhibitor), apocynin (NADPH oxidase inhibitor) and EGCG & ECG (catechins having galloyl group), but not EGC & EC (catechins devoid of galloyl group). Herein, we determined the probable mechanism by which the galloyl group containing catechins inhibit ET-1 induced stimulation of PLD activity by molecular docking analyses based on our biochemical studies. ET-1 induced stimulation of PLD activity was inhibited by SecinH3 (inhibitor of cytohesin). Arf-6 and cytohesin-1 were associated in the cell membrane, which was not inhibited by the catechins during ET-1 treatment to the cells. However, EGCG and ECG inhibited binding of GTPγS with Arf-6 even in presence of cytohesin-1. The molecular docking analyses revealed that the galloyl group containing catechins (EGCG/ECG) with cytohesin1-Arf6GDP, but not the non-galloyl-containing catechins (EGC and EC), prevents GDP/GTP exchange in Arf-6 which seems to be an important mechanism for inhibition of ET-1 induced activation of PLD and subsequently increase in NADPH oxidase activities.

  2. Production of recombinant cholesterol oxidase containing covalently bound FAD in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Molla Gianluca

    2010-04-01

    Full Text Available Abstract Background Cholesterol oxidase is an alcohol dehydrogenase/oxidase flavoprotein that catalyzes the dehydrogenation of C(3-OH of cholesterol. It has two major biotechnological applications, i.e. in the determination of serum (and food cholesterol levels and as biocatalyst providing valuable intermediates for industrial steroid drug production. Cholesterol oxidases of type I are those containing the FAD cofactor tightly but not covalently bound to the protein moiety, whereas type II members contain covalently bound FAD. This is the first report on the over-expression in Escherichia coli of type II cholesterol oxidase from Brevibacterium sterolicum (BCO. Results Design of the plasmid construct encoding the mature BCO, optimization of medium composition and identification of the best cultivation/induction conditions for growing and expressing the active protein in recombinant E. coli cells, concurred to achieve a valuable improvement: BCO volumetric productivity was increased from ~500 up to ~25000 U/L and its crude extract specific activity from 0.5 up to 7.0 U/mg protein. Interestingly, under optimal expression conditions, nearly 55% of the soluble recombinant BCO is produced as covalently FAD bound form, whereas the protein containing non-covalently bound FAD is preferentially accumulated in insoluble inclusion bodies. Conclusions Comparison of our results with those published on non-covalent (type I COs expressed in recombinant form (either in E. coli or Streptomyces spp., shows that the fully active type II BCO can be produced in E. coli at valuable expression levels. The improved over-production of the FAD-bound cholesterol oxidase will support its development as a novel biotool to be exploited in biotechnological applications.

  3. Derivatization of enolic OH of piroxicam: a comparative study on esters and sulfonates

    Energy Technology Data Exchange (ETDEWEB)

    Jayaselli, J.; Cheemala, J. Manila Sagar; Geetha Rani, D.P.; Pal, Sarbani [MNR Post Graduate College, Kukatpally, Hyderabad (India). Dept. of Chemistry]. E-mail: sarbani277@yahoo.com

    2008-07-01

    A number of ester and sulfonate derivatives of piroxicam were prepared via acylation/sulfonation of the enolic OH of piroxicam. All the compounds were evaluated for their chemical stability and cyclooxygenase inhibiting properties. Data suggested that esters could be useful for the development of potential prodrugs. The sulfonate derivatives prepared for the first time were found to be stable. One of them showed a moderately selective COX-2 inhibition over COX-1 and would have lower gastrointestinal side effects than piroxicam due to the masked enolic OH group. A plausible mechanism for the acylation/sulfonation process has been proposed that involves participation of the pyridine moiety of piroxicam. Molecular structure of one of the ester was established for the first time by the crystal structure analysis from X-ray powder data. (author)

  4. Derivatization of enolic OH of piroxicam: a comparative study on esters and sulfonates

    International Nuclear Information System (INIS)

    Jayaselli, J.; Cheemala, J. Manila Sagar; Geetha Rani, D.P.; Pal, Sarbani

    2008-01-01

    A number of ester and sulfonate derivatives of piroxicam were prepared via acylation/sulfonation of the enolic OH of piroxicam. All the compounds were evaluated for their chemical stability and cyclooxygenase inhibiting properties. Data suggested that esters could be useful for the development of potential prodrugs. The sulfonate derivatives prepared for the first time were found to be stable. One of them showed a moderately selective COX-2 inhibition over COX-1 and would have lower gastrointestinal side effects than piroxicam due to the masked enolic OH group. A plausible mechanism for the acylation/sulfonation process has been proposed that involves participation of the pyridine moiety of piroxicam. Molecular structure of one of the ester was established for the first time by the crystal structure analysis from X-ray powder data. (author)

  5. Study of Synthesis Polyethylene glycol oleate Sulfonated as an Anionic Surfactant for Enhanced Oil Recovery (EOR)

    Science.gov (United States)

    Sampora, Yulianti; Juwono, Ariadne L.; Haryono, Agus; Irawan, Yan

    2017-11-01

    Mechanical Enhanced Oil Recovery (EOR) through chemical injection is using an anionic surfactant to improve the recovery of oil residues, particularly in a reservoir area that has certain characteristics. This case led the authors to conduct research on the synthesis of an anionic surfactant based on oleic acid and polyethylene glycol 400 that could be applied as a chemical injection. In this work, we investigate the sulfonation of Polyethylene glycol oleate (PDO) in a sulfuric acid agent. PDO in this experiment was derived from Indonesian palm oil. Variation of mole reactant and reaction time have been studied. The surfactant has been characterized by measuring the interfacial tension, acid value, ester value, saponification value, iodine value, Fourier Transform Infrared (FTIR), and particle size analyzer. There is a new peak at 1170-1178 cm-1 indicating that S=O bond has formed. PDO sulfonate exhibits good surface activity due to interfacial tension of 0,003 mN/m. Thus, polyethylene glycol oleate sulfonate was successfully synthesized and it could be useful as a novel an anionic surfactant.

  6. Enchansing the Ionic Purity of Hydrophilic Channels by Blending Fully Sulfonated Graft Copolymers with PVDF Homopolymer

    DEFF Research Database (Denmark)

    Nielsen, Mads Møller; Ching-Ching Yang, Ami; Jankova Atanasova, Katja

    2013-01-01

    The influence of tuning the ionic content of membranes by blending, as opposed to varying the degree of sulfonation, is evaluated. Membranes of fully sulfonated poly(vinylidene fluoride-co-chlorotrifluoroethylene)-g-poly(styrene sulfonic acid) blended with PVDF were prepared and investigated...

  7. 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.

  8. 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

  9. Site directed mutagenesis of amino acid residues at the active site of mouse aldehyde oxidase AOX1.

    Directory of Open Access Journals (Sweden)

    Silvia Schumann

    Full Text Available Mouse aldehyde oxidase (mAOX1 forms a homodimer and belongs to the xanthine oxidase family of molybdoenzymes which are characterized by an essential equatorial sulfur ligand coordinated to the molybdenum atom. In general, mammalian AOs are characterized by broad substrate specificity and an yet obscure physiological function. To define the physiological substrates and the enzymatic characteristics of mAOX1, we established a system for the heterologous expression of the enzyme in Escherichia coli. The recombinant protein showed spectral features and a range of substrate specificity similar to the native protein purified from mouse liver. The EPR data of recombinant mAOX1 were similar to those of AO from rabbit liver, but differed from the homologous xanthine oxidoreductase enzymes. Site-directed mutagenesis of amino acids Val806, Met884 and Glu1265 at the active site resulted in a drastic decrease in the oxidation of aldehydes with no increase in the oxidation of purine substrates. The double mutant V806E/M884R and the single mutant E1265Q were catalytically inactive enzymes regardless of the aldehyde or purine substrates tested. Our results show that only Glu1265 is essential for the catalytic activity by initiating the base-catalyzed mechanism of substrate oxidation. In addition, it is concluded that the substrate specificity of molybdo-flavoenzymes is more complex and not only defined by the three characterized amino acids in the active site.

  10. Activation of JNK and c-Jun is involved in glucose oxidase-mediated cell death of human lymphoma cells.

    Science.gov (United States)

    Son, Young-Ok; Jang, Yong-Suk; Shi, Xianglin; Lee, Jeong-Chae

    2009-12-31

    Mitogen-activated protein kinases (MAPK) affect the activation of activator protein-1 (AP-1), which plays an important role in regulating a range of cellular processes. However, the roles of these signaling factors on hydrogen peroxide (H(2)O(2))-induced cell death are unclear. This study examined the effects of H(2)O(2) on the activation of MAPK and AP-1 by exposing the cells to H(2)O(2) generated by either glucose oxidase or a bolus addition. Exposing BJAB or Jurkat cells to H(2)O(2) affected the activities of MAPK differently according to the method of H(2)O(2) exposure. H(2)O(2) increased the AP-1-DNA binding activity in these cells, where continuously generated H(2)O(2) led to an increase in mainly the c-Fos, FosB and c-Jun proteins. The c-Jun-NH(2)-terminal kinase (JNK)-mediated activation of c-Jun was shown to be related to the H(2)O(2)-induced cell death. However, the suppression of H(2)O(2)-induced oxidative stress by either JNK inhibitor or c-Jun specific antisense transfection was temporary in the cells exposed to glucose oxidase but not to a bolus H(2)O(2). This was associated with the disruption of death signaling according to the severe and prolonged depletion of reduced glutathione. Overall, these results suggest that H(2)O(2) may decide differently the mode of cell death by affecting the intracellular redox state of thiol-containing antioxidants, and this depends more closely on the duration exposed to H(2)O(2) than the concentration of this agent.

  11. Differential fipronil susceptibility and metabolism in two rice stem borers from China.

    Science.gov (United States)

    Fang, Qi; Huang, Cheng-Hua; Ye, Gong-Yin; Yao, Hong-Wei; Cheng, Jia-An; Akhtar, Zunnu-Raen

    2008-08-01

    The susceptibilities of larvae of two rice stem borers, namely, Chilo suppressalis (Walker) (Lepidoptera: Crambidae) and Sesamia inferens (Walker) (Lepidoptera: Nocutidae) to fipronil and its metabolites were investigated, and then the activities of microsomal O-demethylase, and glutathione transferase (GST) in two species were measured. The metabolism of fipronil in both stem borers was determined in vivo and in vitro. The LD50 value of fipronil to S. inferens was 118.5-fold higher than that of C. suppressalis. The bioassay results offipronil metabolites showed that the toxicities of sulfone and sulfide were higher than fipronil for both species, and the differential toxicity between sulfone and fipronil was remarkable. Alternatively, the activities of microsomal O-demethylase and GST of C. suppressalis were 1.35- and 2.06-fold higher than S. inferens, respectively. The in vivo and in vitro studies on metabolism of fipronil showed that all of fipronil, sulfone, and sulfide were detected and the content of sulfone was higher than sulfide in both stem borers. The residue of sulfone in C. suppressalis was significantly higher than that in S. inferens. These results suggest that the higher activity of mixed function oxidases may cause the higher capacity of C. suppressalis to produce fipronil-sulfone, which is more toxic than fipronil leading to the higher susceptibility of this species.

  12. In vitro reduction of coplanar PCB congeners by ABTS oxidases from the culture of Trametes versicolor

    Energy Technology Data Exchange (ETDEWEB)

    Sonoki, S. [High-Tech Research Center, Azabu Univ., Kanagawa (Japan); Sue, T.; Hisamatsu, S. [Graduate School of Environmental Health, Azabu Univ., Kanagawa (Japan); Nagasaka, H. [Inst. of Environmental Ecology, Shin-Nippon Meteorological and Oceanographical Consultant Co., Ltd., Shizuoka (Japan)

    2004-09-15

    In recent years, the environmental contamination by the harmful polluted chemicals becomes more serious. Among them, especially, the dioxins such as coplanar PCBs (Co-PCBs) and PCDDs are hard to be decomposed due to their stability and hydrophobic nature, leading to the world-wide contamination. To clean up the polluted environment, bioremediation using a microorganism is expected to solve the environmental pollution problem because of cost-effective alternative to the more established engineering method. There are some reports on the biodegradation of dioxins using various organisms, in which basidiomycetes, so-called white-rot fungi, have been extensively studied in the process of lignin degradation. As a result unique extracellular oxidative lignindegrading enzymes, such as lignin peroxidase, manganese-dependent peroxidase and laccase were supposed to be responsible for degrading dioxins. Overall many studies on biodegradation of dioxins or other chlorinated aromatic hydrocarbons have focused on using white-rot fungi; however, few reports referred to the metabolism of these environmental pollutants in the in vitro reaction by use of lignin-degrading enzymes produced by white-rot fungi. In this study, we reported the reduction of levels of Co-PCBs in the in vitro incubation with the fractions which had the oxidase activity toward 2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) in the culture fluid of white-rot fungus, Trametes versicolor.

  13. 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.

  14. Sulfonation degree effect on ion-conducting SPEEK-titanium oxide membranes properties

    Energy Technology Data Exchange (ETDEWEB)

    Marrero, Jacqueline Costa; Gomes, Ailton de Souza; Dutra Filho, José Carlos, E-mail: jacquecosta@gmail.com [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Instituto de Macromoléculas Professora Eloisa Mano; Hui, Wang Shu [Universidade de São Paulo (USP), São Paulo, SP (Brazil). Departamento de Engenharia Metalúrgica e de Materiais; Oliveira, Vivianna Silva de [Escola Técnica Rezende Rammel (ETRR), Rio de Janeiro, RJ (Brazil)

    2017-07-01

    Polymeric membranes were developed using a SPEEK (sulfonated poly(ether ether ketone)) polymer matrix, containing titanium oxide (TiO{sub 2}) (incorporated by sol-gel method). SPEEK with different sulfonation degrees (SD): 63% and 50% were used. The influence of sulfonation degree on membrane properties was investigated. The thermal analysis (TGA and DTGA) and X-ray diffraction (XRD) were carried out to characterize the membranes and electrochemical impedance spectroscopy (EIS) was carried out to evaluate the proton conductivity of the membranes. The proton conductivities in water were of 3.25 to 37.08 mS.cm{sup -1}. Experimental data of impedance spectroscopy were analyzed with equivalent circuits using the Zview software, and the results showed that, the best fitted was at 80 °C. (author)

  15. Carbon dioxide sensing with sulfonated polyaniline

    NARCIS (Netherlands)

    Doan, D.C.T.; Ramaneti, R.; Baggerman, J.; Bent, van der J.; Marcelis, A.T.M.; Tong, H.D.; Rijn, van C.J.M.

    2012-01-01

    The use of polyaniline and especially sulfonated polyaniline (SPAN) is explored for sensing carbon dioxide (CO2) at room temperature. Frequency-dependent AC measurements were carried out to detect changes in impedance of the polymer, drop casted on interdigitated electrodes, when exposed to CO2 gas.

  16. Phytochemical Composition, Antioxidant and Xanthine Oxidase Inhibitory Activities of Amaranthus cruentus L. and Amaranthus hybridus L. Extracts

    Directory of Open Access Journals (Sweden)

    Jeanne F. Millogo

    2012-06-01

    Full Text Available This paper describes a preliminary assessment of the nutraceutical value of Amaranthus cruentus (A. cruentus and Amaranthus hybridus (A. hybridus, two food plant species found in Burkina Faso. Hydroacetonic (HAE, methanolic (ME, and aqueous extracts (AE from the aerial parts were screened for in vitro antioxidant and xanthine oxidase inhibitory activities. Phytochemical analyses revealed the presence of polyphenols, tannins, flavonoids, steroids, terpenoids, saponins and betalains. Hydroacetonic extracts have shown the most diversity for secondary metabolites. The TLC analyses of flavonoids from HAE extracts showed the presence of rutin and other unidentified compounds. The phenolic compound contents of the HAE, ME and AE extracts were determined using the Folin–Ciocalteu method and ranged from 7.55 to 10.18 mg Gallic acid equivalent GAE/100 mg. Tannins, flavonoids, and flavonols ranged from 2.83 to 10.17 mg tannic acid equivalent (TAE/100 mg, 0.37 to 7.06 mg quercetin equivalent (QE /100 mg, and 0.09 to 1.31 mg QE/100 mg, respectively. The betacyanin contents were 40.42 and 6.35 mg Amaranthin Equivalent/100 g aerial parts (dry weight in A. cruentus and A. hybridus, respectively. Free-radical scavenging activity expressed as IC50 (DPPH method and iron reducing power (FRAP method ranged from 56 to 423 µg/mL and from 2.26 to 2.56 mmol AAE/g, respectively. Xanthine oxidase inhibitory activities of extracts of A. cruentus and A. hybridus were 3.18% and 38.22%, respectively. The A. hybridus extract showed the best antioxidant and xanthine oxidase inhibition activities. The results indicated that the phytochemical contents of the two species justify their traditional uses as nutraceutical food plants.

  17. Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

    Directory of Open Access Journals (Sweden)

    Raimondo Maggi

    2016-10-01

    Full Text Available Converting biomass into value-added chemicals holds the key to sustainable long-term carbon resource management. In this context, levulinic acid, which is easily obtained from cellulose, is valuable since it can be transformed into a variety of industrially relevant fine chemicals. Here we present a simple protocol for the selective esterification of levulinic acid using solid acid catalysts. Silica supported sulfonic acid catalysts operate under mild conditions and give good conversion and selectivity with stoichiometric amounts of alcohols. The sulfonic acid groups are tethered to the support using organic tethers. These tethers may help in preventing the deactivation of the active sites in the presence of water.

  18. Glucose oxidase-functionalized fluorescent gold nanoclusters as probes for glucose

    International Nuclear Information System (INIS)

    Xia, Xiaodong; Long, Yunfei; Wang, Jianxiu

    2013-01-01

    Highlights: ► A glucose oxidase/gold nanocluster conjugates formed by etching chemistry. ► Integration of the bioactivities and fluorescence properties within a single unit. ► These conjugates serve as novel fluorescent probe for glucose. -- Abstract: Creation and application of noble metal nanoclusters have received continuous attention. By integrating enzyme activity and fluorescence for potential applications, enzyme-capped metal clusters are more desirable. This work demonstrated a glucose oxidase (an enzyme for glucose)-functionalized gold cluster as probe for glucose. Under physiological conditions, such bioconjugate was successfully prepared by an etching reaction, where tetrakis (hydroxylmethyl) phosphonium-protected gold nanoparticle and thioctic acid-modified glucose oxidase were used as precursor and etchant, respectively. These bioconjugates showed unique fluorescence spectra (λ em max = 650 nm, λ ex max = 507 nm) with an acceptable quantum yield (ca. 7%). Moreover, the conjugated glucose oxidase remained active and catalyzed reaction of glucose and dissolved O 2 to produce H 2 O 2 , which quenched quantitatively the fluorescence of gold clusters and laid a foundation of glucose detection. A linear range of 2.0 × 10 −6 –140 × 10 −6 M and a detection limit of 0.7 × 10 −6 M (S/N = 3) were obtained. Also, another horseradish peroxidase/gold cluster bioconjugate was produced by such general synthesis method. Such enzyme/metal cluster bioconjugates represented a promising class of biosensors for biologically important targets in organelles or cells

  19. Antioxidant, xanthine oxidase and lipoxygenase inhibitory activities and phenolics of Bauhinia rufescens Lam. (Caesalpiniaceae).

    Science.gov (United States)

    Compaoré, M; Lamien, C E; Lamien-Meda, A; Vlase, L; Kiendrebeogo, M; Ionescu, C; Nacoulma, O G

    2012-01-01

    An aqueous acetone extract of the stem with the leaves of Bauhinia rufescens and its fractions were analysed for their antioxidant and enzyme-inhibitory activities, as well as their phytochemical composition. For measurement of the antioxidant activities, the 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzoline-6-sulphonate) and the ferric-reducing methods were used. The results indicated that the aqueous acetone, its ethyl acetate and n-butanol fractions possessed considerable antioxidant activity. Further, the xanthine oxidase and lipoxygenase inhibitory assays showed that the n-butanol fraction possessed compounds that can inhibit both these enzymes. In the phytochemical analysis, the ethyl acetate and the n-butanol fractions of the aqueous acetone extract were screened by HPLC-MS for their phenolic content. The results indicated the presence of hyperoside, isoquercitrin, rutin quercetin, quercitrin, p-coumaric and ferulic acids in the non-hydrolysed fractions. In the hydrolysed fractions, kaempferol, p-coumaric and ferulic acids were identified.

  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. Degradation and contamination of perfluorinated sulfonic acid membrane due to swelling-dehydration cycles

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Morgen, Per; Skou, Eivind Morten

    Formation of sulfonic anhydride S-O-S (from the condensation of sulfonic acids) was known one of the important degradation mechanisms [i] for Nafion membrane under hydrothermal aging condition, which is especially critical for hydrogen fuel cells. Similar mechanism would also have be desirable...... to the membrane degradation in direct methanol fuel cells (DMFCs), where liquid water has direct contact with the electrolyte. An ex-situ experiment was established with swelling-dehydration cycles on the membrane. However, formation of sulfonic anhydride was not detected during the entire treatment; instead...

  2. Methadone, monoamine oxidase, and depression: opioid distribution and acute effects on enzyme activity

    Energy Technology Data Exchange (ETDEWEB)

    Kaufmann, C.A.; Kreek, M.J.; Raghunath, J.; Arns, P.

    1983-09-01

    Narcotic withdrawal is often accompanied by an atypical depression which responds to resumption of narcotics. It was hypothesized that methadone might exert its antidepressant effects through monoamine oxidase (MAO) inhibition. The current study examined /sub 3/H-methadone distribution in rat brain and effects on regional MAO activity with acute doses (2.5 mg/kg) which approximate those found during chronic methadone maintenance in man. Limbic areas (amygdala, basomedial hypothalamus, caudate-putamen, hippocampus, preoptic nucleus), as well as pituitary and liver were assayed for MAO activity and methadone concentration. MAO activities did not differ significantly in acute methadone or saline-treated cage-mates at 1 or 24 hr. The concentrations of methadone at 1 hr ranged between 17 and 223 ng/100 mg wet wt tissue in the preoptic nucleus and pituitary, respectively. No significant correlation was found between change in MAO activity (MAO methadone/MAO saline) and methadone concentration in any region at 1 or 24 hr. This study does not support the hypothesis that methadone acts as an antidepressant through MAO inhibition, at least not following acute administration of this exogenous opioid.

  3. 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...

  4. Structure of choline oxidase in complex with the reaction product glycine betaine.

    Science.gov (United States)

    Salvi, Francesca; Wang, Yuan-Fang; Weber, Irene T; Gadda, Giovanni

    2014-02-01

    Choline oxidase from Arthrobacter globiformis, which is involved in the biosynthesis of glycine betaine from choline, has been extensively characterized in its mechanistic and structural properties. Despite the knowledge gained on the enzyme, the details of substrate access to the active site are not fully understood. The `loop-and-lid' mechanism described for the glucose-methanol-choline enzyme superfamily has not been confirmed for choline oxidase. Instead, a hydrophobic cluster on the solvent-accessible surface of the enzyme has been proposed by molecular dynamics to control substrate access to the active site. Here, the crystal structure of the enzyme was solved in complex with glycine betaine at pH 6.0 at 1.95 Å resolution, allowing a structural description of the ligand-enzyme interactions in the active site. This structure is the first of choline oxidase in complex with a physiologically relevant ligand. The protein structures with and without ligand are virtually identical, with the exception of a loop at the dimer interface, which assumes two distinct conformations. The different conformations of loop 250-255 define different accessibilities of the proposed active-site entrance delimited by the hydrophobic cluster on the other subunit of the dimer, suggesting a role in regulating substrate access to the active site.

  5. Crosstalk between HDAC6 and Nox2-based NADPH oxidase mediates HIV-1 Tat-induced pro-inflammatory responses in astrocytes

    Directory of Open Access Journals (Sweden)

    Gi Soo Youn

    2017-08-01

    Full Text Available Histone deacetylase 6 (HDAC6 likely is important in inflammatory diseases. However, how HDAC6 exerts its effect on inflammatory processes remains unclear. HIV-1 transactivator of transcription (Tat activates NADPH oxidase resulting in generation of reactive oxygen species (ROS, leading to extensive neuro-inflammation in the central nervous system. We investigated the correlation of HDAC6 and NADPH oxidase in HIV-1 Tat-stimulated astrocytes. HDAC6 knockdown attenuated HIV-1 Tat-induced ROS generation and NADPH oxidase activation. HDAC6 knockdown suppressed HIV-1 Tat-induced expression of NADPH oxidase subunits, such as Nox2, p47phox, and p22phox. Specific inhibition of HDAC6 using tubastatin A suppressed HIV-1 Tat-induced ROS generation and activation of NADPH oxidase. N-acetyl cysteine, diphenyl iodonium, and apocynin suppressed HIV-1 Tat-induced expression of HDAC6 and the pro-inflammatory chemokines CCL2, CXCL8, and CXCL10. Nox2 knockdown attenuated HIV-1 Tat-induced HDAC6 expression and subsequent expression of chemokines. The collective results point to the potential crosstalk between HDAC6 and NADPH oxidase, which could be a combined therapeutic target for relief of HIV-1 Tat-mediated neuro-inflammation. Keywords: HIV-1 Tat, HDAC6, NADPH oxidase, ROS, Inflammation, Astrocytes

  6. Andrographolide sulfonate improves Alzheimer-associated phenotypes and mitochondrial dysfunction in APP/PS1 transgenic mice.

    Science.gov (United States)

    Geng, Ji; Liu, Wen; Xiong, Yuyun; Ding, Hongqun; Jiang, Chunhong; Yang, Xiaoling; Li, Xiang; Elgehama, Ahmed; Sun, Yang; Xu, Qiang; Guo, Wenjie; Gao, Jing

    2018-01-01

    Alzheimer's disease is a neurodegenerative disorder with Amyloid-β plaques onset, synaptic damage, and cognitive decline. Aβ deposits cause pathological events including oxidative stress, mitochondrial dysfunction, and neuron death. In this study, APPswe/PSENΔ9 double transgenic mice model was used to imitate Alzheimer's disease and the effect and possible mechanism of Andrographolide sulfonate were examined. Andrographolide sulfonate was given to the mice for 7 months before the onset of Aβ plaque. Spatial memory test showed that Andrographolide sulfonate treatment prevented cognitive decline. Aβ deposits were not affected while hippocampus and synapse damage was significantly alleviated. Mechanism studies showed that oxidative stress and mitochondrial swelling was reduced after Andrographolide sulfonate administration. These findings suggest that Andrographolide sulfonate, which has been applied in clinical medicine, might be a promising therapeutic agent for AD therapy via mitochondria protection. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  7. Preparation and Characterization of Sulfonic Acid Functionalized Silica and Its Application for the Esterification of Ethanol and Maleic Acid

    Science.gov (United States)

    Sirsam, Rajkumar; Usmani, Ghayas

    2016-04-01

    The surface of commercially available silica gel, 60-200 mesh size, was modified with sulfonic acid through surface activation, grafting of 3-Mercaptopropyltrimethoxysilane, oxidation and acidification of 3-Mercaptopropylsilica. Sulfonic Acid Functionalization of Silica (SAFS) was confirmed by Fourier Transform Infra-red (FTIR) spectroscopy and thermal gravimetric analysis. Acid-base titration was used to estimate the cation exchange capacity of the SAFS. Catalytic activity of SAFS was judged for the esterification of ethanol with maleic acid. An effect of different process parameters viz. molar ratio, catalyst loading, speed of agitation and temperature were studied and optimized by Box Behnken Design (BBD) of Response Surface Methodology (RSM). Quadratic model developed by BBD-RSM reasonably satisfied an experimental and predicted values with correlation coefficient value R2 = 0.9504.

  8. In vitro oxidation of indoleacetic acid by soluble auxin-oxidases and peroxidases from maize roots

    International Nuclear Information System (INIS)

    Beffa, R.; Martin, H.V.; Pilet, P.E.

    1990-01-01

    Soluble auxin-oxidases were extracted from Zea mays L. cv LG11 apical root segments and partially separated from peroxidases (EC 1.11.1.7) by size-exclusion chromatography. Auxin-oxidases were resolved into one main peak corresponding to a molecular mass of 32.5 kilodaltons and a minor peak at 54.5 kilodaltons. Peroxidases were separated into at least four peaks, with molecular masses from 32.5 to 78 kilodaltons. In vitro activity of indoleacetic acid-oxidases was dependent on the presence of MnCl 2 and p-coumaric acid. Compound(s) present in the crude extract and several synthetic auxin transport inhibitors (including 2,3,5-triiodobenzoic acid and N-1-naphthylphthalamic acid) inhibited auxin-oxidase activity, but had no effect on peroxidases. The products resulting from the in vitro enzymatic oxidation of [ 3 H]indoleacetic acid were separated by HPLC and the major metabolite was found to cochromatograph with indol-3yl-methanol

  9. Inhibition of xanthine oxidase reduces oxidative stress and improves skeletal muscle function in response to electrically stimulated isometric contractions in aged mice

    Science.gov (United States)

    Ryan, Michael J.; Jackson, Janna R.; Hao, Yanlei; Leonard, Stephen S.; Alway, Stephen E.

    2012-01-01

    Oxidative stress is a putative factor responsible for reducing function and increasing apoptotic signaling in skeletal muscle with aging. This study examined the contribution and functional significance of the xanthine oxidase enzyme as a potential source of oxidant production in aged skeletal muscle during repetitive in situ electrically stimulated isometric contractions. Xanthine oxidase activity was inhibited in young adult and aged mice via a subcutaneously placed time release (2.5 mg/day) allopurinol pellet, 7 days prior to the start of in situ electrically stimulated isometric contractions. Gastrocnemius muscles were electrically activated with 20 maximal contractions for three consecutive days. Xanthine oxidase activity was 65% greater in the gastrocnemius muscle of aged mice compared to young mice. Xanthine oxidase activity also increased after in situ electrically stimulated isometric contractions in muscles from both young (33%) and aged (28%) mice, relative to contralateral non-contracted muscles. Allopurinol attenuated the exercise-induced increase in oxidative stress, but it did not affect the elevated basal levels of oxidative stress that was associated with aging. In addition, inhibition of xanthine oxidase activity decreased caspase 3 activity, but it had no effect on other markers of mitochondrial associated apoptosis. Our results show that compared to control conditions, suppression of xanthine oxidase activity by allopurinol reduced xanthine oxidase activity, H2O2 levels, lipid peroxidation and caspase-3 activity, prevented the in situ electrically stimulated isometric contraction-induced loss of glutathione, prevented the increase of catalase and copper-zinc superoxide dismutase activities, and increased maximal isometric force in the plantar flexor muscles of aged mice after repetitive electrically evoked contractions. PMID:21530649

  10. Vicarious trial-and-error behavior and hippocampal cytochrome oxidase activity during Y-maze discrimination learning in the rat.

    Science.gov (United States)

    Hu, Dan; Xu, Xiaojuan; Gonzalez-Lima, Francisco

    2006-03-01

    The present study investigated whether more vicarious trial-and-error (VTE) behavior, defined by head movement from one stimulus to another at a choice point during simultaneous discriminations, led to better visual discrimination learning in a Y-maze, and whether VTE behavior was a function of the hippocampus by measuring regional brain cytochrome oxidase (C.O.) activity, an index of neuronal metabolic activity. The results showed that the more VTEs a rat made, the better the rat learned the visual discrimination. Furthermore, both learning and VTE behavior during learning were correlated to C.O. activity in the hippocampus, suggesting that the hippocampus plays a role in VTE behavior during discrimination learning.

  11. Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids

    Science.gov (United States)

    Cooper, George W.; Thiemens, Mark H.; Jackson, Teresa L.; Chang, Sherwood

    1997-01-01

    Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

  12. Formation of core (polystyrene)-shell (polybenzimidazole) nanoparticles using sulfonated polystyrene as template.

    Science.gov (United States)

    Hazarika, Mousumi; Arunbabu, Dhamodaran; Jana, Tushar

    2010-11-15

    We report formation of core (polystyrene)-shell (polybenzimidazole) nanoparticles from a new blend system consisting of an amorphous polymer polybenzimidazole (PBI) and an ionomer sodium salt of sulfonated polystyrene (SPS-Na). The ionomer used for the blending is spherical in shape with sulfonate groups on the surface of the particles. An in depth investigation of the blends at various sulfonation degrees and compositions using Fourier transform infrared (FT-IR) spectroscopy provides direct evidence of specific hydrogen bonding interactions between the N-H groups of PBI and the sulfonate groups of SPS-Na. The disruption of PBI chains self association owing to the interaction between the functional groups of these polymer pairs is the driving force for the blending. Thermodynamical studies carried out by using differential scanning calorimeter (DSC) establish partially miscible phase separated blending of these polymers in a wider composition range. The two distinguishable glass transition temperatures (T(g)) which are different from the neat components and unaltered with the blends composition attribute that the domain size of heterogeneity (d(d)) of the blends is >20 nm since one of the blend component (SPS-Na particle) diameter is ∼70 nm. The diminish of PBI chains self association upon blending with SPS-Na particles and the presence of invariant T(g)'s of the blends suggest the wrapping of PBI chains over the SPS-Na spherical particle surface and hence resulting a core-shell morphology. Transmission electron microscopy (TEM) study provides direct evidence of core-shell nanoparticle formation; where core is the polystyrene and shell is the PBI. The sulfonation degree affects the blends phase separations. The higher degree of sulfonation favors the disruption of PBI self association and thus forms partially miscible two phases blends with core-shell morphology. Copyright © 2010 Elsevier Inc. All rights reserved.

  13. Increase in activity, glycosylation and expression of cytokinin oxidase/dehydrogenase during the senescence of barley leaf segments in the dark

    Czech Academy of Sciences Publication Activity Database

    Conrad, K.; Motyka, Václav; Schlüter, T.

    2007-01-01

    Roč. 130, č. 4 (2007), s. 572-579 ISSN 0031-9317 R&D Projects: GA ČR GA206/03/0313 Institutional research plan: CEZ:AV0Z50380511 Source of funding: V - iné verejné zdroje Keywords : OXIDASE ACTIVITY * GENE-EXPRESSION * ZEA - MAYS Subject RIV: EF - Botanics Impact factor: 2.192, year: 2007

  14. Kinetic investigations of graft copolymerization of sodium styrene sulfonate onto electron beam irradiated poly(vinylidene fluoride) films

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud Nasef, Mohamed, E-mail: mahmoudeithar@fkkksa.utm.m [Institute of Hydrogen Economy, International City Campus, Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia); Chemical Engineering Department, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Saidi, Hamdani [Institute of Hydrogen Economy, International City Campus, Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia); Chemical Engineering Department, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Mohd Dahlan, Khairul Zaman [Radiation Processing Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

    2011-01-15

    Graft copolymerization of sodium styrene sulfonate (SSS) onto electron beam (EB) irradiated poly(vinylidene fluoride) (PVDF) films was investigated to find out a simple preparation process for sulfonic acid proton exchange membranes with respect to monomer concentration, absorbed dose, temperature, film thickness and storage time. The reaction order of the monomer concentration and absorbed dose of grafting was found to be 2.84 and 1.20, respectively. The overall activation energy for graft copolymerization reaction was calculated to be 11.36 kJ/mol. The initial rate of grafting was found to decrease with an increase in the film thickness. The trapped radicals in the irradiated PVDF films remained effective in initiating the reaction without considerable loss in grafting level up to 180 days, when stored under -60 {sup o}C. The presence and distribution of polystyrene sulfonate grafts in the obtained membranes were observed by Fourier transform infrared (FTIR) spectroscopic analysis, scanning optical microscope and scanning transmission electron microscopy (STEM) coupled with X-ray energy dispersive (EDX), respectively.

  15. Radiation effects on diamine oxidase activities in intestine and plasma of the rat

    International Nuclear Information System (INIS)

    Ely, M.J.; Speicher, J.M.; Snyder, S.L.; Catravas, G.N.

    1985-01-01

    Diamine oxidase (DAO; EC 1.4.3.6) activity was measured in plasma and ileal tissue homogenates prepared from male Sprague-Dawley rats sacrificed at 1-15 days after acute whole-body irradiation with 14.5-MeV electrons. Animals irradiated with 1 Gy showed no significant changes in plasma and ileal DAO activities through day 13 relative to nonirradiated controls. Animals irradiated with 5, 10 and 12 Gy displayed marked declines in ileal DAO, with levels reaching a nadir on day 3. This was paralleled by a decrease in plasma DAO activity in all three dose groups. Recovery of ileal and plasma DAO levels was later seen as early as day 4 in animals irradiated with 5 and 10 Gy doses, but animals receiving 12 Gy did not survive beyond day 3. A further study highlights the relationship between radiation dose and levels of plasma and mucosal DAO on day 3, the time of maximum decrease at all doses tested. Mucosal DAO activity decreased almost linearly with doses up to 6 Gy. Plasma DAO levels closely paralleled the dose dependency of the mucosal levels. These data suggest that plasma DAO activity might be useful as a readily measurable marker of intestinal epithelial injury and recovery after acute radiation exposure

  16. Evaluation of genotoxic activity of maleic hydrazide, ethyl methane sulfonate, and N-nitroso diethylamine in Tradescantia.

    Science.gov (United States)

    Alvarez-Moya, C; Santerre-Lucas, A; Zúñiga-González, G; Torres-Bugarín, O; Padilla-Camberos, E; Feria-Velasco, A

    2001-01-01

    To assess the genotoxic activity of N-nitroso diethylamine (NDEA), maleic hydrazide (MH), and ethyl methane sulfonate (EMS) using two systems: the comet assay on nuclei from Tradescantia, and the pink mutation test on Tradescantia staminal hairs (clone 4430). Tradescantia cups was obtained from Laboratorio de Citogenética y Mutagénesis del Centro de Ciencias de la Atmósfera de la Universidad Nacional Autónoma de México and treated with: N-nitroso diethylamine (NDEA) at 1, 5, 10 mM, maleic hydrazide (MH) at 1, 5, 10 mM and ethyl methane sulfonate (EMS) at 15, 30 and 45 mM; and used in both pink mutation assay and comet assay using cellular nuclei from Tradescantia staminal hairs. The observation of staminal hair was realized along eight days (6-14) after treatment), flowers produced day 14 after treatment were utilized done according to Underbrink. In previous reports on plants, were comet assay was used, breaking cellular wall and separating by centrifugation gradient are necessary. Here, nuclei from staminal hairs were obtained by squashing the cells (is not necessary to utilize to break special procedure cellular wall), collected using a nylon mesh of 80 Mm and next the comet assay was applied. Student's T test was the statistical test used for analyzing the comet assay data. Both assays showed a great sensitivity to the studied mutagens. A relationship between the dose-pink event and the dose-tail length was evident. Even though the Tradescantia mutation assay is a sensitive test with MH and EMS, low doses of NDEA were not able to induce a significant increase in the pink event frequencies; however, the comet assay was able to detect the mutagenic effect of NDEA at the same dose. Thus, it is clear that the comet assay is highly sensitive to the lowest dose of chemical mutagens. The comet assay on nuclei from Tradescantia staminal hairs is a useful tool to monitor genotoxic agents; it is simple, highly sensitive, and faster than the pink mutation test.

  17. Surface modification of carbon fibers by a polyether sulfone emulsion sizing for increased interfacial adhesion with polyether sulfone

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Haojie [National Engineering Laboratory for Carbon Fiber Technology, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Shouchun, E-mail: zschun@sxicc.ac.cn [National Engineering Laboratory for Carbon Fiber Technology, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); Lu, Chunxiang [National Engineering Laboratory for Carbon Fiber Technology, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)

    2014-10-30

    Highlights: • A polyether sulfone emulsion (PES) sizing was prepared for the first time. • The sizing enhanced the surface activity and wettability of carbon fibers. • Compared to the original sizing, the PES emulsion sizing resulted in an 18.4% increase in the interlaminar shear strength of carbon fiber/PES composites. • Important influences of emulsifier on the fiber surface and composite interface were demonstrated. • The reinforcing mechanisms are the improved fiber surface wettability and interfacial compatibility in composites. - Abstract: Interests on carbon fiber-reinforced thermoplastic composites are growing rapidly, but the challenges with poor interfacial adhesion have slowed their adoption. In this work, a polyether sulfone (PES) emulsion sizing was prepared successfully for increased interfacial adhesion of carbon fiber/PES composites. To obtain a high-quality PES emulsion sizing, the key factor, emulsifier concentration, was studied by dynamic light scattering technique. The results demonstrated that the suitable weight ratio of PES to emulsifier was 8:3, and the resulting PES emulsion sizing had an average particle diameter of 117 nm and Zeta potential of −52.6 mV. After sizing, the surface oxygen-containing functional groups, free energy and wettability of carbon fibers increased significantly, which were advantageous to promote molecular-level contact between carbon fiber and PES. Finally, short beam shear tests were performed to evaluate the interfacial adhesion of carbon fiber/PES composites. The results indicated that PES emulsion sizing played a critical role for the enhanced interfacial adhesion in carbon fiber/PES composites, and a 26% increase of interlaminar shear strength was achieved, because of the improved fiber surface wettability and interfacial compatibility between carbon fiber and PES.

  18. Surface modification of carbon fibers by a polyether sulfone emulsion sizing for increased interfacial adhesion with polyether sulfone

    International Nuclear Information System (INIS)

    Yuan, Haojie; Zhang, Shouchun; Lu, Chunxiang

    2014-01-01

    Highlights: • A polyether sulfone emulsion (PES) sizing was prepared for the first time. • The sizing enhanced the surface activity and wettability of carbon fibers. • Compared to the original sizing, the PES emulsion sizing resulted in an 18.4% increase in the interlaminar shear strength of carbon fiber/PES composites. • Important influences of emulsifier on the fiber surface and composite interface were demonstrated. • The reinforcing mechanisms are the improved fiber surface wettability and interfacial compatibility in composites. - Abstract: Interests on carbon fiber-reinforced thermoplastic composites are growing rapidly, but the challenges with poor interfacial adhesion have slowed their adoption. In this work, a polyether sulfone (PES) emulsion sizing was prepared successfully for increased interfacial adhesion of carbon fiber/PES composites. To obtain a high-quality PES emulsion sizing, the key factor, emulsifier concentration, was studied by dynamic light scattering technique. The results demonstrated that the suitable weight ratio of PES to emulsifier was 8:3, and the resulting PES emulsion sizing had an average particle diameter of 117 nm and Zeta potential of −52.6 mV. After sizing, the surface oxygen-containing functional groups, free energy and wettability of carbon fibers increased significantly, which were advantageous to promote molecular-level contact between carbon fiber and PES. Finally, short beam shear tests were performed to evaluate the interfacial adhesion of carbon fiber/PES composites. The results indicated that PES emulsion sizing played a critical role for the enhanced interfacial adhesion in carbon fiber/PES composites, and a 26% increase of interlaminar shear strength was achieved, because of the improved fiber surface wettability and interfacial compatibility between carbon fiber and PES

  19. Colonic necrosis due to calcium polystyrene sulfonate (Kalimate not suspended in sorbitol

    Directory of Open Access Journals (Sweden)

    María Dolores Castillo-Cejas

    2013-04-01

    Full Text Available Cation-exchange resins are used in the management of hyperkalemia, particularly in patients with end-stage renal disease. These resins were associated with gastrointestinal tract lesions, especially sodium polystyrene sulfonate (Kayexalate mixed with sorbitol. We present a case of colonic necrosis after the administration of calcium polystyrene sulfonate (Kalimate not suspended in sorbitol.

  20. 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

  1. Glucose oxidase-functionalized fluorescent gold nanoclusters as probes for glucose

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Xiaodong [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Long, Yunfei, E-mail: l_yunfei927@163.com [School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Wang, Jianxiu, E-mail: jxiuwang@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2013-04-15

    Highlights: ► A glucose oxidase/gold nanocluster conjugates formed by etching chemistry. ► Integration of the bioactivities and fluorescence properties within a single unit. ► These conjugates serve as novel fluorescent probe for glucose. -- Abstract: Creation and application of noble metal nanoclusters have received continuous attention. By integrating enzyme activity and fluorescence for potential applications, enzyme-capped metal clusters are more desirable. This work demonstrated a glucose oxidase (an enzyme for glucose)-functionalized gold cluster as probe for glucose. Under physiological conditions, such bioconjugate was successfully prepared by an etching reaction, where tetrakis (hydroxylmethyl) phosphonium-protected gold nanoparticle and thioctic acid-modified glucose oxidase were used as precursor and etchant, respectively. These bioconjugates showed unique fluorescence spectra (λ{sub em} {sub max} = 650 nm, λ{sub ex} {sub max} = 507 nm) with an acceptable quantum yield (ca. 7%). Moreover, the conjugated glucose oxidase remained active and catalyzed reaction of glucose and dissolved O{sub 2} to produce H{sub 2}O{sub 2}, which quenched quantitatively the fluorescence of gold clusters and laid a foundation of glucose detection. A linear range of 2.0 × 10{sup −6}–140 × 10{sup −6} M and a detection limit of 0.7 × 10{sup −6} M (S/N = 3) were obtained. Also, another horseradish peroxidase/gold cluster bioconjugate was produced by such general synthesis method. Such enzyme/metal cluster bioconjugates represented a promising class of biosensors for biologically important targets in organelles or cells.

  2. Sulfonation of cPTFE Film grafted Styrene for Proton Exchange Membrane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Yohan Yohan

    2010-10-01

    Full Text Available Sulfonation of γ-ray iradiated and styrene-grafted crosslinked polytetrafluoroethylene film (cPTFE-g-S film have been done. The aim of the research is to make hydropyl membrane as proton exchange membrane fuel cell. Sulfonation was prepared with chlorosulfonic acid in chloroethane under various conditions. The impact of the percent of grafting, the concentration of chlorosulfonic acid, the reaction time,and the reaction temperature on the properties of sulfonated film is examinated. The results show that sulfonation of surface-grafted films is incomplete at room  temperature. The increasing of concentration of chlorosulfonic acid and reaction temperature accelerates the reaction but they also add favor side reactions. These will lead to decreasing of the ion-exchange capacity, water uptake, and proton conductivity but increasing the resistance to oxidation in a perhidrol solution. The cPTFE-g-SS membrane which is resulted has stability in a H2O2 30% solution for 20 hours.

  3. Role of TLR4/NADPH oxidase/ROS-activated p38 MAPK in VCAM-1 expression induced by lipopolysaccharide in human renal mesangial cells

    Directory of Open Access Journals (Sweden)

    Lee I-Ta

    2012-11-01

    Full Text Available Abstract Background In bacteria-induced glomerulonephritis, Toll-like receptor 4 (TLR4 activation by lipopolysaccharide (LPS, a key component of the outer membranes of Gram-negative bacteria can increase oxidative stress and the expression of vascular cell adhesion molecule-1 (VCAM-1, which recruits leukocytes to the glomerular mesangium. However, the mechanisms underlying VCAM-1 expression induced by LPS are still unclear in human renal mesangial cells (HRMCs. Results We demonstrated that LPS induced VCAM-1 mRNA and protein levels associated with an increase in the promoter activity of VCAM-1, determined by Western blot, RT-PCR, and promoter assay. LPS-induced responses were inhibited by transfection with siRNAs of TLR4, myeloid differentiation factor 88 (MyD88, Nox2, Nox4, p47phox, c-Src, p38 MAPK, activating transcription factor 2 (ATF2, and p300 or pretreatment with the inhibitors of reactive oxygen species (ROS, edaravone, NADPH oxidase [apocynin (APO or diphenyleneiodonium chloride (DPI], c-Src (PP1, p38 MAPK (SB202190, and p300 (GR343. LPS induced NADPH oxidase activation, ROS production, and p47phox translocation from the cytosol to the membrane, which were reduced by PP1 or c-Src siRNA. We observed that LPS induced TLR4, MyD88, c-Src, and p47phox complex formation determined by co-immunoprecipitation and Western blot. We further demonstrated that LPS stimulated ATF2 and p300 phosphorylation and complex formation via a c-Src/NADPH oxidase/ROS/p38 MAPK pathway. Up-regulation of VCAM-1 led to enhancing monocyte adhesion to HRMCs challenged with LPS, which was inhibited by siRNAs of c-Src, p47phox, p38 MAPK, ATF2, and p300 or pretreatment with an anti-VCAM-1 neutralizing antibody. Conclusions In HRMCs, LPS-induced VCAM-1 expression was, at least in part, mediated through a TLR4/MyD88/ c-Src/NADPH oxidase/ROS/p38 MAPK-dependent p300 and ATF2 pathway associated with recruitment of monocyte adhesion to kidney. Blockade of these pathways may

  4. Synthesis and Characterization of Sulfonated Poly(Phenylene Containing a Non-Planar Structure and Dibenzoyl Groups

    Directory of Open Access Journals (Sweden)

    Hohyoun Jang

    2016-02-01

    Full Text Available Polymers for application as sulfonated polyphenylene membranes were prepared by nickel-catalyzed carbon-carbon coupling reaction of bis(4-chlorophenyl-1,2-diphenylethylene (BCD and 1,4-dichloro-2,5-dibenzoylbenzene (DCBP. Conjugated cis/trans isomer (BCD had a non-planar conformation containing four peripheral aromatic rings that facilitate the formation of π–π interactions. 1,4-Dichloro-2,5-dibenzoylbenzene was synthesized from the oxidation reaction of 2,5-dichloro-p-xylene, followed by Friedel-Crafts reaction with benzene. DCBP monomer had good reactivity in polymerization affecting the activity of benzophenone as an electron-withdrawing group. The polyphenylene was sulfonated using concentrated sulfuric acid. These polymers without any ether linkages on the polymer backbone were protected from nucleophilic attack by hydrogen peroxide, hydroxide anion, and radicals generated by polymer electrolyte membrane fuel cell (PEMFC operation systems. The mole fraction of the sulfonic acid groups was controlled by varying the mole ratio of bis(4-chlorophenyl-1,2-diphenylethylene in the copolymer. In comparison with Nafion 211® membrane, these SBCDCBP membranes showed ion exchange capacity (IEC ranging from 1.04 to 2.07 meq./g, water uptake from 36.5% to 69.4%, proton conductivity from 58.7 to 101.9 mS/cm, and high thermal stability.

  5. Impact of single anaerobic exercise on delayed activation of endothelial xanthine oxidase in men and women.

    Science.gov (United States)

    Wiecek, Magdalena; Maciejczyk, Marcin; Szymura, Jadwiga; Kantorowicz, Malgorzata; Szygula, Zbigniew

    2017-11-01

    The aim of the study was to evaluate the activity of xanthine oxidase (XO) in the blood of men and women during the first hour following a single anaerobic exercise (AN-EX), and after 24 hours of recovery, and to determine whether the changes in XO activity in the blood after AN-EX are dependent on anaerobic performance. Ten men and ten women performed a single AN-EX. Blood was collected before and five times after completion of the AN-EX. The activity of XO was determined. In both groups, a significant (P women (P work performed during the AN-EX and the power decrease. In the first hour after the single AN-EX, XO activity in the blood of women and men did not change, but after 24 hours of recovery, it was significantly higher compared to baseline levels in both sexes. Single AN-EX causes a smaller increase in XO activity in people with higher anaerobic performance.

  6. Ionomers based on multisulfonated perylene dianhydride: Synthesis and properties of water resistant sulfonated polyimides

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Feng; Li, Nanwen [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Suobo; Li, Shenghai [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China)

    2010-04-15

    A novel locally and densely sulfonated dianhydride with four sulfonic acid groups, 1,6,7,12-tetra[4-(sulfonic acid)phenoxy]perylene-3,4,9,10-tetracarboxylic dianhydride (SPTDA), was successfully synthesized by direct sulfonation of the parent dianhydride, 1,6,7,12-tetraphenoxyperylene-3,4,9,10-tetracarboxylic dianhydride (PTDA). Sulfonated copolyimides were prepared from SPTDA, nonsulfonated dianhydride 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianydride, 4,4'-diaminodiphenyl ether (a) or dodecane-1,12-diamine (b). The synthesized copolymers, with the -SO{sub 3}H group on the polymer side chain, possess high molecular weights and high viscosities, and they form tough, flexible membranes. The copolymer membrane with an ion exchange capacity of 2.69 mequiv. g{sup -1} had a proton conductivity of 0.126 S cm{sup -1} at 20 C and 0.292 S cm{sup -1} at 100 C; the latter is much higher than that of Nafion {sup registered} 117 under the same conditions. The mechanical properties of the copolymer membranes were almost unchanged after accelerated water stability testing at 140 C for 100 h; this indicates excellent hydrolytic stability of the synthesized copolyimides. (author)

  7. Aryl sulfonate based anticancer alkylating agents.

    Science.gov (United States)

    Sheikh, Hamdullah Khadim; Arshad, Tanzila; Kanwal, Ghazala

    2018-05-01

    This research work revolves around synthesis of antineoplastic alkylating sulfonate esters with dual alkylating sites for crosslinking of the DNA strands. These molecules were evaluated as potential antineoplastic cross linking alkylating agents by reaction with the nucleoside of Guanine DNA nucleobase at both ends of the synthesized molecule. Synthesis of the alkylating molecules and the crosslinking with the guanosine nucleoside was monitored by MALDITOF mass spectroscopy. The synthesized molecule's crosslinking or adduct forming rate with the nucleoside was compared with that of 1,4 butane disulfonate (busulfan), in form of time taken for the appearance of [M+H] + . It was found that aryl sulfonate leaving group was causing higher rate of nucleophilic attack by the Lewis basic site of the nucleobase. Furthermore, the rate was also found to be a function of electron withdrawing or donating nature of the substituent on the aryl ring. Compound with strong electron withdrawing substituent on the para position of the ring reacted fastest. Hence, new alkylating agents were synthesized with optimized or desired reactivity.

  8. 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.

  9. A multicopper oxidase-related protein is essential for insect viability, longevity and ovary development.

    Science.gov (United States)

    Peng, Zeyu; Green, Peter G; Arakane, Yasuyuki; Kanost, Michael R; Gorman, Maureen J

    2014-01-01

    Typical multicopper oxidases (MCOs) have ten conserved histidines and one conserved cysteine that coordinate four copper atoms. These copper ions are required for oxidase activity. During our studies of insect MCOs, we discovered a gene that we named multicopper oxidase-related protein (MCORP). MCORPs share sequence similarity with MCOs, but lack many of the copper-coordinating residues. We identified MCORP orthologs in many insect species, but not in other invertebrates or vertebrates. We predicted that MCORPs would lack oxidase activity due to the absence of copper-coordinating residues. To test this prediction, we purified recombinant Tribolium castaneum (red flour beetle) MCORP and analyzed its enzymatic activity using a variety of substrates. As expected, no oxidase activity was detected. To study MCORP function in vivo, we analyzed expression profiles of TcMCORP and Anopheles gambiae (African malaria mosquito) MCORP, and assessed RNAi-mediated knockdown phenotypes. We found that both MCORPs are constitutively expressed at a low level in all of the tissues we analyzed. Injection of TcMCORP dsRNA into larvae resulted in 100% mortality prior to adult eclosion, with death occurring mainly during the pharate pupal stage or late pharate adult stage. Injection of TcMCORP dsRNA into pharate pupae resulted in the death of approximately 20% of the treated insects during the pupal to adult transition and a greatly shortened life span for the remaining insects. In addition, knockdown of TcMCORP in females prevented oocyte maturation and, thus, greatly decreased the number of eggs laid. These results indicate that TcMCORP is an essential gene and that its function is required for reproduction. An understanding of the role MCORP plays in insect physiology may help to develop new strategies for controlling insect pests.

  10. Low serum diamine oxidase (DAO) activity levels in patients with migraine.

    Science.gov (United States)

    Izquierdo-Casas, Joan; Comas-Basté, Oriol; Latorre-Moratalla, M Luz; Lorente-Gascón, Marian; Duelo, Adriana; Vidal-Carou, M Carmen; Soler-Singla, Luis

    2018-02-01

    Histamine intolerance is a disorder in the homeostasis of histamine due to a reduced intestinal degradation of this amine, mainly caused by a deficiency in the enzyme diamine oxidase (DAO). Among the several multi-faced symptoms associated with histamine intolerance, headache is one of the most recognized and disabling consequences. The aim of this study was to determine the prevalence of DAO deficiency in patients with a confirmed migraine diagnosis according to the current International Headache Society (IHS) and in non-migraine subjects. DAO activity was assessed in a total of 198 volunteers recruited at the Headache Unit of the Hospital General de Catalunya, 137 in the migraine group and 61 as a control group. DAO enzyme activity in blood samples was determined by ELISA test. Values below 80 HDU/ml (Histamine Degrading Unit/ml) were considered as DAO deficient. Mean value of DAO activity from migraine population (64.5 ± 33.5 HDU/ml) was significantly lower (p < 0.0001) than that obtained from healthy volunteers (91.9 ± 44.3 HDU/ml). DAO deficiency was more prevalent in migraine patients than in the control group. A high incidence rate of DAO deficiency (87%) was observed in the group of patients with migraine. On the other hand, 44% of non-migranous subjects had levels of DAO activity lower than 80 HDU/ml. Despite the multifactorial aetiology of migraine, these results seem to indicate that this enzymatic deficit could be related to the onset of migraine.

  11. Systemic Manifestations in Pyridox(am)ine 5'-Phosphate Oxidase Deficiency.

    Science.gov (United States)

    Guerriero, Réjean M; Patel, Archana A; Walsh, Brian; Baumer, Fiona M; Shah, Ankoor S; Peters, Jurriaan M; Rodan, Lance H; Agrawal, Pankaj B; Pearl, Phillip L; Takeoka, Masanori

    2017-11-01

    Pyridoxine is converted to its biologically active form pyridoxal-5-phosphate (P5P) by the enzyme pyridox(am)ine 5'-phosphate oxidase and serves as a cofactor in nearly 200 reactions in the central nervous system. Pyridox(am)ine 5'-phosphate oxidase deficiency leads to P5P dependent epilepsy, typically a neonatal- or infantile-onset epileptic encephalopathy treatable with P5P or in some cases, pyridoxine. Following identification of retinopathy in a patient with pyridox(am)ine 5'-phosphate oxidase deficiency that was reversible with P5P therapy, we describe the systemic manifestations of pyridox(am)ine 5'-phosphate oxidase deficiency. A series of six patients with homozygous mutations of PNPO, the gene coding pyridox(am)ine 5'-phosphate oxidase, were evaluated in our center over the course of two years for phenotyping of neurological and systemic manifestations. Five of six were born prematurely, three had anemia and failure to thrive, and two had elevated alkaline phosphatase. A movement disorder was observed in two children, and a reversible retinopathy was observed in the most severely affected infant. All patients had neonatal-onset epilepsy and were on a continuum of developmental delay to profound encephalopathy. Electroencephalographic features included background slowing and disorganization, absent sleep features, and multifocal and generalized epileptiform discharges. All the affected probands carried a homozygous PNPO mutation (c.674 G>T, c.686 G>A and c.352G>A). In addition to the well-described epileptic encephalopathy, pyridox(am)ine 5'-phosphate oxidase deficiency causes a range of neurological and systemic manifestations. A movement disorder, developmental delay, and encephalopathy, as well as retinopathy, anemia, and failure to thrive add to the broadening clinical spectrum of P5P dependent epilepsy. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. 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)

  13. 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)

  14. Composite plasma polymerized sulfonated polystyrene membrane for PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Nath, Bhabesh Kumar; Khan, Aziz; Chutia, Joyanti, E-mail: jchutiaiasst@gmail.com

    2015-10-15

    Highlights: • Methyl methane sulfonate (MMS) is used as the sulfonating agent. • The proton conductivity of the membrane is found to be 0.141 S cm{sup −1}. • Power density of fuel cell with styrene/MMS membrane is 0.5 W cm{sup −2}. • The membrane exhibits thermal stability up to 140 °C. - Abstract: This work presents the introduction of an organic compound methyl methane sulfonate (MMS) for the first time in fabrication of polystyrene based proton exchange membrane (PEM) by plasma polymerization process. The membrane is fabricated by co-polymerizing styrene and MMS in capacitively coupled continuous RF plasma. The chemical composition of the plasma polymerized polymer membrane is investigated using Fourier Transform Infrared Spectroscopy which reveals the formation of composite structure of styrene and MMS. The surface morphology studied using AFM and SEM depicts the effect of higher partial pressure of MMS on surface topography of the membrane. The proton transport property of the membrane studied using electrochemical impedance spectroscopy shows the achievement of maximum proton conductivity of 0.141 S cm{sup −1} which is comparable to Nafion 117 membrane. Fuel cell performance test of the synthesized membrane shows a maximum power density of 500 mW cm{sup −2} and current density of 0.62 A cm{sup −2} at 0.6 V.

  15. Safrole oxide induces neuronal apoptosis through inhibition of integrin beta4/SOD activity and elevation of ROS/NADPH oxidase activity.

    Science.gov (United States)

    Su, Le; Zhao, BaoXiang; Lv, Xin; Wang, Nan; Zhao, Jing; Zhang, ShangLi; Miao, JunYing

    2007-02-20

    Neuronal apoptosis is a very important event in the development of the central nervous system (CNS), but the underlying mechanisms remain to be elucidated. We have previously shown that safrole oxide, a small molecule, induces integrin beta4 expression and promotes apoptosis in vascular endothelial cells. In this study, the effects of safrole oxide on cell growth and apoptosis have been examined in primary cultures of mouse neurons. Safrole oxide was found to significantly inhibit neuronal cell growth and to induce apoptosis. The inhibitory and apoptotic activities of safrole oxide followed a dose- and time-dependent manner. Interestingly, the expression of integrin beta4 was significantly inhibited with safrole oxide treatment. Furthermore, safrole oxide dramatically increases the level of intracellular reactive oxygen species (ROS) and the activity of NADPH oxidase. Moreover, manganese-dependent superoxide dismutase (MnSOD) activity was decreased significantly with safrole oxide treatment. Our study thus demonstrates that safrole oxide induces neuronal apoptosis through integrin beta4, ROS, NADPH, and MnSOD.

  16. Monoamine oxidase B (MAO-B) inhibition by active principles from Uncaria rhynchophylla.

    Science.gov (United States)

    Hou, Wen-Chi; Lin, Rong-Dih; Chen, Cheng-Tang; Lee, Mei-Hsien

    2005-08-22

    Attenuation of monoamine oxidase B (MAO-B) activity may provide protection against oxidative neurodegeneration. For this reason, inhibition of MAO-B activity is used as part of the treatment of Parkinson's and Alzheimer's patients. The hook of Uncaria rhynchophylla (Miq.) Jacks. (Rubiaceae) is a traditional Chinese herbal drug that is generally used to treat convulsive disorders. In this study, the fractionation and purification of Uncaria rhynchophylla extracts using a bioguided assay isolated two known compounds, (+)-catechin and (-)-epicatechin. The compounds inhibited MAO-B, as measured by an assay of rat brain MAO-B separated by electrophoresis on a 7.5% native polyacrylamide gel. The IC(50) values of (+)-catechin and (-)-epicatechin were 88.6 and 58.9 microM, respectively, and inhibition occurred in a dose-dependent manner, as measured by the fluorescence method. The Lineweaver-Burk plot revealed K(i) values for (+)-catechin and (-)-epicatechin of 74 and 21 microM, respectively. This suggests that these two compounds, isolated here for the first time from Uncaria rhynchophylla, might be able to protect against neurodegeneration in vitro, and, therefore, the molecular mechanism deserves further study. This finding may also increase interest in the health benefits of Uncaria rhynchophylla.

  17. 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.

  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. NADPH oxidase is involved in regulation of gene expression and ROS overproduction in soybean (Glycine max L. seedlings exposed to cadmium

    Directory of Open Access Journals (Sweden)

    Jagna Chmielowska-Bąk

    2017-06-01

    Full Text Available Cadmium-induced oxidative burst is partially mediated by NADPH oxidase. The aim of the present research was to evaluate the role of NADPH oxidase in soybeans’ response to short-term cadmium stress. The application of an NADPH oxidase inhibitor, diphenyleneiodonium chloride (DPI, affected expression of two Cd-inducible genes, encoding DOF1 and MYBZ2 transcription factors. This effect was observed after 3 h of treatment. Interestingly, Cd-dependent increases in NADPH oxidase activity occurred only after a period of time ranging from 6 and 24 h of stress. Stimulation of the enzyme correlated in time with a significant accumulation of reactive oxygen species (ROS. Further analysis revealed that pharmacological inhibition of NADPH oxidase activity during 24 h of Cd stress does not affect Cd uptake, seedling growth, or the level of lipid peroxidation. The role of NADPH oxidase in the response of soybean seedlings to short-term Cd exposure is discussed.

  20. The cytochemical demonstration of catalase and D-amino acid oxidase in the microbodies of teleost kidney cells

    NARCIS (Netherlands)

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

    1977-01-01

    The distribution of catalase and D-amino acid oxidase, marker enzymes for peroxisomes, was determined cytochemically in the kidney tubules of an euryhaline teleost, the three-spined stickleback. Catalase activity was localized with the diaminobenzidine technique. The presence of D-amino acid oxidase

  1. Physico-chemistry characterization of sulfonated polyacrylamide polymers for use in polymer flooding

    Energy Technology Data Exchange (ETDEWEB)

    Rashidi, Masoud

    2010-07-01

    Hydrolyzed polyacrylamide polymer (HPAM) as a feasible and effective viscosifier has been fully studied and used for polymer flooding processes in several oil field, e.g. Daqing oil field. It has been shown that Hydrolyzed polyacrylamide polymers (HPAM) may be a good choice for high temperature condition with no oxygen and no divalent ions presence. At high temperature and high salinity conditions, polymer may precipitates and loss their viscosyfing properties. Also adsorption and retention of polymer in porous medium may change rheological properties of polymers. Thus, the viscosyfing property of polymers is influenced by several important parameters, e.g. salinity, hardness, temperature, adsorption, retention, polymer structure, and etc. By replacing some of carboxylate group of HPAM with another monomer, e.g. sodium salt of acrylic acid and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), effect of high salinity/hardness and temperature seems to be reduced specially for the samples with higher percentage of AMPS co-monomer. The ultimate aim of this work is to develop an understanding of the sulfonated polyacrylamide copolymers with a range of different sulfonation and molecular weight at high salinity and high temperature conditions. Most of the work in this thesis deals with viscosity and adsorption/retention measurements of the sulfonated copolymers and HPAM. The factors which may affect the viscosity of the polymers and have been identified in this work as most likely influencing also adsorption and retention of the polymers are shear rate, polymer concentration, sulfonation degree, molecular weight, NaCl concentration, divalent ion concentration, and temperature. (Author)

  2. 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 ...

  3. Novel p47phox-related organizers regulate NADPH oxidase 1 (Nox1) activity and localization

    Science.gov (United States)

    Gianni, Davide; Diaz, Begoña; Taulet, Nicolas; Fowler, Bruce; Courtneidge, Sara A.; Bokoch, Gary M.

    2010-01-01

    The mechanisms that determine localized formation of reactive oxygen species (ROS) via NADPH oxidases (Nox) in nonphagocytic cells are unknown. We show that the c-Src substrate proteins Tks4 and Tks5 are functional members of a p47phox-related organizer superfamily. Tks proteins selectively support Nox1 and Nox3 (vs. Nox2 and Nox4) activity in reconstituted cellular systems, and interact with the NoxA1 activator protein through an SH3-mediated interaction. Endogenous Tks4 is required for Rac GTPase-dependent ROS production by DLD1 colon cancer cells. Tks4 recruits Nox1 to invadopodia that form in DLD1 cells in a Tks- and Nox-dependent fashion. We propose that Tks organizers represent novel members of an organizer superfamily that link Nox to localized ROS formation. PMID:19755710

  4. Design, synthesis and inhibitory activities of 8-(substituted styrol-formamido)phenyl-xanthine derivatives on monoamine oxidase B.

    Science.gov (United States)

    Hu, Suwen; Nian, Siyun; Qin, Kuiyou; Xiao, Tong; Li, Lingna; Qi, Xiaolu; Ye, Faqing; Liang, Guang; Hu, Guoxin; He, Jincai; Yu, Yinfei; Song, Bo

    2012-01-01

    The design and synthesis of two series of 8-(substituted styrol-formamido)phenyl-xanthine derivatives are described. Their in vitro monoamine oxidase B (MAO-B) inhibition were tested and the effect of substituents on the N-7, phenyl and the substituted positions are discussed. It was observed that compound 9b displayed significant MAO-B inhibition activity and selectivity, fluorine substitution plays a key role in the selectivity of MAO-B inhibition, and the styrol-formamido group at position-3' may enhance the activity and selectivity of 8-phenyl-xanthine analogues. These results suggest that such compounds may be utilized for the development of new candidate MAO-B inhibitors for treatment of Parkinson's disease.

  5. Secreted fungal sulfhydryl oxidases: sequence analysis and characterisation of a representative flavin-dependent enzyme from Aspergillus oryzae

    Directory of Open Access Journals (Sweden)

    Faccio Greta

    2010-08-01

    Full Text Available Abstract Background Sulfhydryl oxidases are flavin-dependent enzymes that catalyse the formation of de novo disulfide bonds from free thiol groups, with the reduction of molecular oxygen to hydrogen peroxide. Sulfhydryl oxidases have been investigated in the food industry to remove the burnt flavour of ultraheat-treated milk and are currently studied as potential crosslinking enzymes, aiming at strengthening wheat dough and improving the overall bread quality. Results In the present study, potential sulfhydryl oxidases were identified in the publicly available fungal genome sequences and their sequence characteristics were studied. A representative sulfhydryl oxidase from Aspergillus oryzae, AoSOX1, was expressed in the fungus Trichoderma reesei. AoSOX1 was produced in relatively good yields and was purified and biochemically characterised. The enzyme catalysed the oxidation of thiol-containing compounds like glutathione, D/L-cysteine, beta-mercaptoethanol and DTT. The enzyme had a melting temperature of 57°C, a pH optimum of 7.5 and its enzymatic activity was completely inhibited in the presence of 1 mM ZnSO4. Conclusions Eighteen potentially secreted sulfhydryl oxidases were detected in the publicly available fungal genomes analysed and a novel proline-tryptophan dipeptide in the characteristic motif CXXC, where X is any amino acid, was found. A representative protein, AoSOX1 from A. oryzae, was produced in T. reesei in an active form and had the characteristics of sulfhydryl oxidases. Further testing of the activity on thiol groups within larger peptides and on protein level will be needed to assess the application potential of this enzyme.

  6. Secreted fungal sulfhydryl oxidases: sequence analysis and characterisation of a representative flavin-dependent enzyme from Aspergillus oryzae.

    Science.gov (United States)

    Faccio, Greta; Kruus, Kristiina; Buchert, Johanna; Saloheimo, Markku

    2010-08-20

    Sulfhydryl oxidases are flavin-dependent enzymes that catalyse the formation of de novo disulfide bonds from free thiol groups, with the reduction of molecular oxygen to hydrogen peroxide. Sulfhydryl oxidases have been investigated in the food industry to remove the burnt flavour of ultraheat-treated milk and are currently studied as potential crosslinking enzymes, aiming at strengthening wheat dough and improving the overall bread quality. In the present study, potential sulfhydryl oxidases were identified in the publicly available fungal genome sequences and their sequence characteristics were studied. A representative sulfhydryl oxidase from Aspergillus oryzae, AoSOX1, was expressed in the fungus Trichoderma reesei. AoSOX1 was produced in relatively good yields and was purified and biochemically characterised. The enzyme catalysed the oxidation of thiol-containing compounds like glutathione, D/L-cysteine, beta-mercaptoethanol and DTT. The enzyme had a melting temperature of 57°C, a pH optimum of 7.5 and its enzymatic activity was completely inhibited in the presence of 1 mM ZnSO4. Eighteen potentially secreted sulfhydryl oxidases were detected in the publicly available fungal genomes analysed and a novel proline-tryptophan dipeptide in the characteristic motif CXXC, where X is any amino acid, was found. A representative protein, AoSOX1 from A. oryzae, was produced in T. reesei in an active form and had the characteristics of sulfhydryl oxidases. Further testing of the activity on thiol groups within larger peptides and on protein level will be needed to assess the application potential of this enzyme.

  7. Granzyme B of cytotoxic T cells induces extramitochondrial reactive oxygen species production via caspase-dependent NADPH oxidase activation.

    Science.gov (United States)

    Aguiló, Juan I; Anel, Alberto; Catalán, Elena; Sebastián, Alvaro; Acín-Pérez, Rebeca; Naval, Javier; Wallich, Reinhard; Simon, Markus M; Pardo, Julián

    2010-07-01

    Induction of reactive oxygen species (ROS) is a hallmark of granzyme B (gzmB)-mediated pro-apoptotic processes and target cell death. However, it is unclear to what extent the generated ROS derive from mitochondrial and/or extra-mitochondrial sources. To clarify this point, we have produced a mutant EL4 cell line, termed EL4-rho(0), which lacks mitochondrial DNA, associated with a decreased mitochondrial membrane potential and a defective ROS production through the electron transport chain of oxidative phosphorylation. When incubated with either recombinant gzmB plus streptolysin or ex vivo gzmB(+) cytotoxic T cells, EL4-rho(0) cells showed phosphatydylserine translocation, caspase 3 activation, Bak conformational change, cytochrome c release and apoptotic morphology comparable to EL4 cells. Moreover, EL4-rho(0) cells produced ROS at levels similar to EL4 under these conditions. GzmB-mediated ROS production was almost totally abolished in both cell lines by the pan-caspase inhibitor, Z-VAD-fmk. However, addition of apocynin, a specific inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, led to a significant reduction of ROS production and cell death only in EL4-rho(0) but not EL4 cells. These data suggest that gzmB-induced cell death is accompanied by a caspase-dependent pathway of extra-mitochondrial ROS production, most probably through activation of NADPH oxidase.

  8. Novel p47(phox)-related organizers regulate localized NADPH oxidase 1 (Nox1) activity.

    Science.gov (United States)

    Gianni, Davide; Diaz, Begoña; Taulet, Nicolas; Fowler, Bruce; Courtneidge, Sara A; Bokoch, Gary M

    2009-09-15

    The mechanisms that determine localized formation of reactive oxygen species (ROS) through NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase (Nox) family members in nonphagocytic cells are unknown. We show that the c-Src substrate proteins Tks4 (tyrosine kinase substrate with four SH3 domains) and Tks5 are functional members of a p47(phox)-related organizer superfamily. Tks proteins selectively support Nox1 and Nox3 (and not Nox2 and Nox4) activity in reconstituted cellular systems and interact with the NoxA1 activator protein through an Src homology 3 domain-mediated interaction. Endogenous Tks4 is required for Rac guanosine triphosphatase- and Nox1-dependent ROS production by DLD1 colon cancer cells. Our results are consistent with the Tks-mediated recruitment of Nox1 to invadopodia that form in DLD1 cells in a Tks- and Nox-dependent fashion. We propose that Tks organizers represent previously unrecognized members of an organizer superfamily that link Nox to localized ROS formation.

  9. Proximity does not contribute to activity enhancement in the glucose oxidase-horseradish peroxidase cascade

    Science.gov (United States)

    Zhang, Yifei; Tsitkov, Stanislav; Hess, Henry

    2016-12-01

    A proximity effect has been invoked to explain the enhanced activity of enzyme cascades on DNA scaffolds. Using the cascade reaction carried out by glucose oxidase and horseradish peroxidase as a model system, here we study the kinetics of the cascade reaction when the enzymes are free in solution, when they are conjugated to each other and when a competing enzyme is present. No proximity effect is found, which is in agreement with models predicting that the rapidly diffusing hydrogen peroxide intermediate is well mixed. We suggest that the reason for the activity enhancement of enzymes localized by DNA scaffolds is that the pH near the surface of the negatively charged DNA nanostructures is lower than that in the bulk solution, creating a more optimal pH environment for the anchored enzymes. Our findings challenge the notion of a proximity effect and provide new insights into the role of DNA scaffolds.

  10. Preparation and Characterization of Sulfonated Poly (ether ether ...

    African Journals Online (AJOL)

    NJD

    2007-08-10

    Aug 10, 2007 ... Preparation and Characterization of Sulfonated Poly (ether ... Currently perfluori- ... with phosphoric acid solution according to the method described earlier.11,12 ... where A is the membrane area available for diffusion; CA is.

  11. Perfluorooctane sulfonate (PFOS) depletion in beef cattle

    Science.gov (United States)

    Perfluorooctane sulfonate (PFOS) is an industrial chemical that is used as a surfactant in several manufactured consumer products but is also a breakdown product from other chemical surfactants. As a result of its extensive use, PFOS is ubiquitous in the environment and is often detected in biosoli...

  12. Room temperature synthesis of biodiesel using sulfonated ...

    Science.gov (United States)

    Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature. Prepared for submission to Royal Society of Chemistry (RSC) journal, Green Chemistry as a communication.

  13. Polar extracts from (Tunisian Acacia salicina Lindl. Study of the antimicrobial and antigenotoxic activities

    Directory of Open Access Journals (Sweden)

    Boubaker Jihed

    2012-04-01

    Full Text Available Abstract Background Methanolic, aqueous and Total Oligomer Flavonoids (TOF-enriched extracts obtained from the leaves of Acacia salicina 'Lindl.' were investigated for antibacterial, antimutagenic and antioxidant activities. Methods The antimicrobial activity was tested on the Gram positive and Gram negative reference bacterial strains. The Mutagenic and antimutagenic activities against direct acting mutagens, methylmethane sulfonate (MMS and 4-nitro-o-phenylenediamine (NOPD, and indirect acting mutagens, 2-aminoanthracene (2-AA and benzo[a]pyrene (B(aP were performed with S. typhimurium TA102 and TA98 assay systems. In addition, the enzymatic and nonenzymatic methods were employed to evaluate the anti-oxidative effects of the tested extracts. Results A significant effect against the Gram positive and Gram negative reference bacterial strains was observed with all the extracts. The mutagenic and antimutagenic studies revealed that all the extracts decreased the mutagenicity induced by B(aP (7.5 μg/plate, 2-AA (5 μg/plate, MMS (1.3 mg/plate and NOPD (10 μg/plate. Likewise, all the extracts showed an important free radical scavenging activity towards the superoxide anion generated by the xanthine/xanthine oxidase assay system, as well as high Trolox Equivalent Antioxidant Capacity (TEAC, against the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS+• radical. TOF-enriched extract exhibited the highest protective effect against free radicals, direct acting-mutagen and metabolically activated S9-dependent mutagens. Conclusions The present study indicates that the extracts from A. salicina leaves are a significant source of compounds with the antimutagenic and antioxidant activities, and this may be useful for developing potential chemopreventive substances.

  14. H2O2 and NADPH oxidases involve in regulation of 2-(2-phenylethyl)chromones accumulation during salt stress in Aquilaria sinensis calli.

    Science.gov (United States)

    Wang, Xiaohui; Dong, Xianjuan; Feng, Yingying; Liu, Xiao; Wang, Jinling; Zhang, Zhongxiu; Li, Jun; Zhao, Yunfang; Shi, Shepo; Tu, Pengfei

    2018-04-01

    2-(2-Phenylethyl)chromones are the main compounds responsible for the quality of agarwood, which is widely used in traditional medicines, incenses and perfumes. H 2 O 2 and NADPH oxidases (also known as respiratory burst oxidase homologs, Rbohs) mediate diverse physiological and biochemical processes in environmental stress responses. However, little is known about the function of H 2 O 2 and NADPH oxidases in 2-(2-phenylethyl)chromones accumulation. In this study, we found that salt stress induced a transient increase in content of H 2 O 2 and 2-(2-phenylethyl)chromones accumulation in Aquilaria sinensis calli. Exogenous H 2 O 2 remarkably decreased the production of 2-(2-phenylethyl)chromones, while dimethylthiourea (DMTU), a scavenger of H 2 O 2 , significantly increased 2-(2-phenylethyl)chromones accumulation in salt treated calli. Three new H 2 O 2 -generating genes, named AsRbohA-C, were isolated and characterized from A. sinensis. Salt stress also induced a transient increase in AsRbohA-C expression and NADPH oxidase activity. Furthermore, exogenous H 2 O 2 increased AsRbohA-C expression and NADPH oxidase activity, while DMTU inhibited AsRbohA-C expression and NADPH oxidase activity under salt stress. Moreover, diphenylene iodonium (DPI), the inhibitor of NADPH oxidases, reduced AsRbohA-C expression and NADPH oxidase activity, but significantly induced 2-(2-phenylethyl)chromones accumulation during salt stress. These results clearly demonstrated the central role of H 2 O 2 and NADPH oxidases in regulation of salt-induced 2-(2-phenylethyl)chromones accumulation in A. sinensis calli. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. 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.

  16. 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...

  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. Ionomeric membranes based on partially sulfonated poly(styrene) : synthesis, proton conduction and methanol permeation

    NARCIS (Netherlands)

    Picchioni, F.; Tricoli, V.; Carretta, N.

    2000-01-01

    Homogeneuosly sulfonated poly(styrene) (SPS) was prepared with various concentration of sulfonic acid groups in the base polymer. Membranes cast from these materials were investigated in relation to proton conductivity and methanol permeability in the temperature range from 20°C to 60°C. It was

  19. Ionomeric membranes based on partially sulfonated poly(styrene): synthesis, proton conduction and methanol permeation

    NARCIS (Netherlands)

    Carretta, N.; Tricoli, V.; Picchioni, F.

    2000-01-01

    Homogeneuosly sulfonated poly(styrene) (SPS) was prepared with various concentration of sulfonic acid groups in the base polymer. Membranes cast from these materials were investigated in relation to proton conductivity and methanol permeability in the temperature range from 20°C to 60°C. It was

  20. 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

  1. Functional heterogeneity of NADPH oxidase-mediated contractions to endothelin with vascular aging.

    Science.gov (United States)

    Meyer, Matthias R; Barton, Matthias; Prossnitz, Eric R

    2014-11-24

    Aging, a physiological process and main risk factor for cardiovascular and renal diseases, is associated with endothelial cell dysfunction partly resulting from NADPH oxidase-dependent oxidative stress. Because increased formation of endothelium-derived endothelin-1 (ET-1) may contribute to vascular aging, we studied the role of NADPH oxidase function in age-dependent contractions to ET-1. Renal arteries and abdominal aortas from young and old C57BL6 mice (4 and 24 months of age) were prepared for isometric force measurements. Contractions to ET-1 (0.1-100 nmol/L) were determined in the presence and absence of the NADPH oxidase-selective inhibitor gp91ds-tat (3 μmol/L). To exclude age-dependent differential effects of NO bioactivity between vascular beds, all experiments were conducted in the presence of the NO synthase inhibitor L-NAME (300 μmol/L). In young animals, ET-1-induced contractions were 6-fold stronger in the renal artery than in the aorta (prenal artery and aorta, respectively (pAging had no effect on NADPH oxidase-dependent and -independent contractions to ET-1 in the renal artery. In contrast, contractions to ET-1 were markedly reduced in the aged aorta (5-fold, page-dependent heterogeneity of NADPH oxidase-mediated vascular contractions to ET-1, demonstrating an inherent resistance to functional changes in the renal artery but not in the aorta with aging. Thus, local activity of NADPH oxidase differentially modulates responses to ET-1 with aging in distinct vascular beds. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Perfluoroalkyl sulfonates cause alkyl chain length-dependent hepatic steatosis and hypolipidemia mainly by impairing lipoprotein production in APOE*3-leiden CETP mice

    NARCIS (Netherlands)

    Bijland, S.; Rensen, P.C.N.; Pieterman, E.J.; Maas, A.C.E.; Hoorn, J.W. van der; Erk, M.J. van; Havekes, L.M.; Dijk, K.W. van; Chang, S.C.; Ehresman, D.J.; Butenhoff, J.L.; Princen, H.M.G.

    2011-01-01

    Perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) are stable perfluoroalkyl sulfonate (PFAS) surfactants, and PFHxS and PFOS are frequently detected in human biomonitoring studies. Some epidemiological studies have shown modest positive

  3. 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

  4. The Initial Comparison Study of Sodium Lignosulfonate, Sodium Dodecyl Benzene Sulfonate, and Sodium p-Toluene Sulfonate Surfactant for Enhanced Oil Recovery

    Science.gov (United States)

    Khoirul Anas, Argo; Iman Prakoso, Nurcahyo; Sasvita, Dilla

    2018-04-01

    Surfactant (surface active agent) exhibit numerous interesting properties that enable their use as additional component in mobilising of residual oil from capillary pore after secondary recovery process using gas injection and water flooding. In this study, Sodium Lignosulfonate (SLS) surfactant was successfully synthesized by applying batch method using lignin from oil palm empty fruit bunches as precursor. Furthermore, its performance in reducing interfacial tension of crude oil and formation water colloidal system was compared with commercial available surfactant including Sodium Dodecyl Benzene Sulfonate (SDBS) and Sodium p-Toluene Sulfonate (SpTS). The synthesized SLS surfactant was characterized by using Fourier Transform Infrared (FTIR) spectroscopy. Meanwhile, its performance in reducing interfacial tension of crude oil and formation water colloidal system was analyzed by using compatibility test, phase behaviour analysis, and interfacial tension (IFT) measurement. The compatibility test shows that SLS, SDBS, and SpTS surfactants were compatible with formation water. In addition, the phase behaviour analysis shows that SLS surfactant was better than SpTS surfactant, while SDBS surfactant generates the highest performance proved by the best microemulsion formation resulted by SDBS. Furthermore, the optimum concentration of SLS, SDBS, and SpTS surfactants in reducing the interfacial tension of crude oil and formation water was 1.0%. The IFT measurement indicates that the performance of SLS with the value of 1.67 mN/m was also better than SpTS surfactant with the value of 3.59 mN/m. Meanwhile, SDBS surfactant shows the best performance with the IFT value of 0.47 mN/m.

  5. Carnosine: effect on aging-induced increase in brain regional monoamine oxidase-A activity.

    Science.gov (United States)

    Banerjee, Soumyabrata; Poddar, Mrinal K

    2015-03-01

    Aging is a natural biological process associated with several neurological disorders along with the biochemical changes in brain. Aim of the present investigation is to study the effect of carnosine (0.5-2.5μg/kg/day, i.t. for 21 consecutive days) on aging-induced changes in brain regional (cerebral cortex, hippocampus, hypothalamus and pons-medulla) mitochondrial monoamine oxidase-A (MAO-A) activity with its kinetic parameters. The results of the present study are: (1) The brain regional mitochondrial MAO-A activity and their kinetic parameters (except in Km of pons-medulla) were significantly increased with the increase of age (4-24 months), (2) Aging-induced increase of brain regional MAO-A activity including its Vmax were attenuated with higher dosages of carnosine (1.0-2.5μg/kg/day) and restored toward the activity that observed in young, though its lower dosage (0.5μg/kg/day) were ineffective in these brain regional MAO-A activity, (3) Carnosine at higher dosage in young rats, unlike aged rats significantly inhibited all the brain regional MAO-A activity by reducing their only Vmax excepting cerebral cortex, where Km was also significantly enhanced. These results suggest that carnosine attenuated the aging-induced increase of brain regional MAO-A activity by attenuating its kinetic parameters and restored toward the results of MAO-A activity that observed in corresponding brain regions of young rats. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

  6. The Effect of MethyI Jasmonate on Ethylene Production, ACC Oxidase Activity and Carbon Dioxide Evolution in the Yellowish-Tangerine Tomato Fruits (Lycopersicon esculentum Mill.

    Directory of Open Access Journals (Sweden)

    Janusz Czapski

    2013-12-01

    Full Text Available The yellowish-tangerine tomato (cv. Bursztyn in the green, light yellow and yellow stages of ripening were treated with 0.1% and 1.0% of methyl jasmonate (JA-Me in lanolin paste and kept for several days and then they were evaluated for production of ethylene, ACC oxidase activity and CO2 evolution. Production of endogenous ethylene in mature green fruits was low and increased during ripening. JA-Me stimulated ethylene production and ACC oxidase activity in all investigated stages of fruit ripening. Slices excised from mature green fruits produced highest amount of carbon dioxide as compared to more advanced stages of ripening. JA-Me in O,1 % and 1,0% concentrations increased significantly CO2 evolution in green fruits, while in light yellow and yellow fruits only higher concentration of JA-Me stimulated carbon dioxide production.

  7. 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.

  8. Mediation of glycosylated and partially-deglycosylated glucose oxidase of Aspergillus niger by a ferrocene-derivatised detergent.

    Science.gov (United States)

    Fraser, D M; Zakeeruddin, S M; Grätzel, M

    1992-01-30

    A ferrocene-derivatised detergent, (11-ferrocenylundecyl) trimethylammonium bromide (FTMAB), when oxidised to the corresponding ferricinium ion, was found by electrochemical studies to be an effective electron acceptor for reduced glucose oxidase of Aspergillus niger (EC 1.13.4) and thus acts as a electron-transfer mediator between glucose oxidase and a working electrode held at a potential sufficiently positive to reoxidise reduced FTMAB. An increase in mediating activity was produced when FTMAB was present in concentrations above its critical micelle concentration. An 'enzyme electrode' was formed by adsorption of glucose oxidase and FTMAB surfactant on a graphite rod. The electrode functioned as an amperometric biosensor for glucose in phosphate-buffered saline solution. A mixed micelle of glucose oxidase and FTMAB, probably adsorbed on the electrode surface, appears to be advantageous for the amperometric determination of glucose. Additionally, glucose oxidase was treated with alpha-mannosidase. When this partially-deglycosylated glucose oxidase was incorporated in an enzyme electrode, a 100-fold increase in the second-order rate constant (k) for electron transfer between the enzyme and FTMAB was observed, together with increased current densities, with respect to the equivalent values for FTMAB and commercial glucose oxidase. The use of deglycosylated enzymes in biosensors is suggested.

  9. Active site intermediates in the reduction of O(2) by cytochrome oxidase, and their derivatives.

    Science.gov (United States)

    Wikström, Mårten

    2012-04-01

    The mechanism of dioxygen activation and reduction in cell respiration, as catalysed by cytochrome c oxidase, has a long history. The work by Otto Warburg, David Keilin and Britton Chance defined the dioxygen-binding heme iron centre, viz. das Atmungsferment, or cytochrome a(3). Chance brought the field further in the mid-1970's by ingenious low-temperature studies that for the first time identified the primary enzyme-substrate (ES) Michaelis complex of cell respiration, the dioxygen adduct of heme a(3), which he termed Compound A. Further work using optical, resonance Raman, EPR, and other sophisticated spectroscopic techniques, some of which with microsecond time resolution, has brought us to the situation today, where major principles of how O(2) reduction occurs in respiration are well understood. Nonetheless, some questions have remained open, for example concerning the precise structures, catalytic roles, and spectroscopic properties of the breakdown products of Compound A that have been called P, F (for peroxy and ferryl), and O (oxidised). This nomenclature has been known to be inadequate for some time already, and an alternative will be suggested here. In addition, the multiple forms of P, F and O states have been confusing, a situation that we endeavour to help clarifying. The P and F states formed artificially by reacting cytochrome oxidase with hydrogen peroxide are especially scrutinised, and some novel interpretations will be given that may account for previously unexplained observations. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Destruction of gel sulfonated cation-exchangers of the KU-2 type under the influence of hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Roginskaya, B.S.; Zavadovskaya, A.S.; Znamenskii, Yu.P.; Paskhina, N.A.; Dobrova, E.I.

    1988-10-20

    The purpose of this work was to study the mechanism of interaction of Soviet sulfonated cation-exchangers of the KU-2 type with hydrogen peroxide. It is shown that under the influence of hydrogen peroxide sulfonated cation-exchangers begin, after a certain induction period, to lose capacity and to release destruction products into water; the length of the induction period increases with the degree of cross-linking. In a given time of contact between the resin and the solution the degree of destruction falls with increase of cross-linking. The principal product of destruction of sulfonated cation-exchangers is an aromatic sulfonic acid containing oxidized groups in the side chains.

  11. 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.

  12. Evaluation of genotoxic activity of maleic hydrazide, ethyl methane sulfonate, and N-nitroso diethylamine in Tradescantia

    Directory of Open Access Journals (Sweden)

    Alvarez-Moya Carlos

    2001-01-01

    Full Text Available Objective. To assess the genotoxic activity of N-nitroso diethylamine (NDEA, maleic hydrazide (MH, and ethyl methane sulfonate (EMS using two systems: the comet assay on nuclei from Tradescantia, and the pink mutation test on Tradescantia staminal hairs (clone 4430. Material and Methods. Tradescantia cups was obtained from Laboratorio de Citogenética y Mutagénesis del Centro de Ciencias de la Atmósfera de la Universidad Nacional Autónoma de México and treated with: N-nitroso diethylamine (NDEA at 1, 5, 10 mM, maleic hidrazide (MH at 1, 5, 10 mM and ethyl methane sulfonate (EMS at 15, 30 and 45 mM; and used in both pink mutation assay and comet assay using cellular nuclei from Tradescantia staminal hairs. The observation of staminal hair was realized along eight days (6-14 after treatment, flowers produced day 14 after treatment were utilized done according to Underbrink. In previous reports on plants, were comet assay was used, breaking cellular wall and separating by centrifugation gradient are necessary. Here, nuclei from staminal hairs were obtained by squashing the cells (is not necessary to utilize to break special procedure cellular wall, collected using a nylon mesh of 80Mm and next the comet assay was applied. Student's T test was the statistical test used for analyzing the comet assay data. Results. Both assays showed a great sensitivity to the studied mutagens. A relationship between the dose-pink event and the dose-tail length was evident. Even though the Tradescantia mutation assay is a sensitive test with MH and EMS, low doses of NDEA were not able to induce a significant increase in the pink event frequencies; however, the comet assay was able to detect the mutagenic effect of NDEA at the same dose. Thus, it is clear that the comet assay is highly sensitive to the lowest dose of chemical mutagens. Conclusions. The comet assay on nuclei from Tradescantia staminal hairs is a useful tool to monitor genotoxic agents; it is simple

  13. Involvement of abscisic acid in regulating antioxidative defense systems and IAA-oxidase activity and improving adventitious rooting in mung bean [Vigna radiata (L.) Wilczek] seedlings under cadmium stress.

    Science.gov (United States)

    Li, Shi-Weng; Leng, Yan; Feng, Lin; Zeng, Xiao-Ying

    2014-01-01

    In vitro experiments were conducted to investigate the effects of abscisic acid (ABA) and Cd on antioxidative defense systems and indole-3-acetic acid (IAA) oxidase during adventitious rooting in mung bean [Vigna radiata (L.) Wilczek] seedlings. The exogenous ABA significantly enhanced the number and fresh weight of the adventitious roots. CdCl2 strongly inhibited adventitious rooting. Pretreatment with 10 μM ABA clearly alleviated the inhibitory effect of Cd on rooting. ABA significantly reduced superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), and catalase (CAT) activities, as well as the levels of glutathione (GSH) and ascorbic acid (ASA) during adventitious rooting. ABA strongly increased IAA-oxidase activity during the induction (0-12 h) and expression (after 48 h) phases and increased the phenols levels. Cd treatment significantly reduced the activities of SOD, APX, POD, and IAA oxidase, as well as GSH level. Cd strongly increased ASA levels. ABA pretreatment counteracted Cd-induced alterations of certain antioxidants and antioxidative enzymes, e.g., remarkably rescued APX and POD activities, reduced the elevated SOD and CAT activities and ASA levels, and recovered the reduced GSH levels, caused by Cd stress. Thus, the physiological effects of the combination of ABA and Cd treatments were opposite of those obtained with Cd treatment alone, suggesting that ABA involved in the regulation of antioxidative defense systems and the alleviation of wounding- and Cd-induced oxidative stress.

  14. Evaluation of the toxicological effects of perfluorooctane sulfonic acid in the common carp (Cyprinus carpio)

    International Nuclear Information System (INIS)

    Hoff, P.T.; Dongen, W. van; Esmans, E.L.; Blust, R.; Coen, W.M. de

    2003-01-01

    In the present study we evaluated the toxicological effects of a scarcely documented environmental pollutant, perfluorooctane sulfonic acid (PFOS), on selected biochemical endpoints in the common carp, Cyprinus carpio. Juvenile organisms were exposed to PFOS through a single intraperitoneal injection (liver concentrations ranging from 16 to 864 ng/g after 5 days of exposure) and after 1 and 5 days effects were assessed in liver and serum of the exposed organisms. The investigation of the hepatotoxicity of PFOS included the determination of the peroxisome proliferating potential (peroxisomal palmitoyl CoA oxidase and catalase activity) and the compounds influence on the average DNA basepair length (ABPL) by agarose gel electrophoresis. Total antioxidant activity (TAA), cholesterol and triglyceride levels were monitored in the serum. After 1 day of exposure the ABPL was significantly increased in the 270 and 864 ng/g treatment groups. After 5 days of exposure significant increases relative to the control were observed for the 16, 270 and 864 ng/g treatment groups. Enzyme leakage from the liver was investigated by measurement of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in the serum. At 561, 670 and 864 ng/g PFOS a significant increase in serum ALT activity became apparent after 5 days of exposure with values ranging from 159 to 407% relative to the control. For serum AST activity a significant increase for the 864 ng/g treatment group was observed with a value of 112% relative to the control. Determination of the polymorphonuclear leukocyte migration into liver tissue as assessed through myeloperoxidase (MPO) activity in liver, was used as an indicator for inflammation. It appeared that inflammation was not involved in the observed membranous enzyme leakage for the 561, 670 and 864 ng/g PFOS treatment groups. The results of this study suggest that PFOS induces inflammation-independent enzyme leakage through liver cell membranes

  15. 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...

  16. Activity and population dynamics of heterotrophic and ammonia-oxidizing microorganisms in soil surrounding sludge bands spiked with linear alkylbenzene sulfonate

    DEFF Research Database (Denmark)

    Brandt, K. K.; Sørensen, J.; Krogh, P. H.

    2003-01-01

    Recent research has documented soil microorganisms to be rather sensitive to linear alkylbenzene sulfonates (LAS), which may enter the soil environment in considerable quantities following sewage sludge disposal. We here report field effects of LAS on selected microbial populations present in a s...

  17. 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

  18. The role of lignin sulfonate in flotation of bastnasite from barite

    International Nuclear Information System (INIS)

    Gerdel, M.A.; Smith, R.W.

    1988-01-01

    In carboxylate collector flotation of bastnasite from other semisoluble salt type minerals such as barite various modifiers must be added in order to achieve selective flotation. One such modifier is a lignin sulfonate. It may function in part by acting as a sequestrant for metal ions present, preventing autoactivation in the system by metal ions derived from the minerals themselves. It also functions as a depressant for barite than for bastnasite. The authors suggest that the strong depressing action on barite is related to a good fit of the sulfonate into the barite structure

  19. 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.

  20. Potato and Mushroom Polyphenol Oxidase Activities Are Differently Modulated by Natural Plant Extracts

    NARCIS (Netherlands)

    Kuijpers, T.F.M.; Herk, van T.; Vincken, J.P.; Janssen, R.H.; Narh, D.L.; Berkel, van W.J.H.; Gruppen, H.

    2014-01-01

    Enzymatic browning is a major quality issue in fruit and vegetable processing and can be counteracted by different natural inhibitors. Often, model systems containing a single polyphenol oxidase (PPO) are used to screen for new inhibitors. To investigate the impact of the source of PPO on the

  1. Development of 2-(Substituted Benzylamino)-4-Methyl-1, 3-Thiazole-5-Carboxylic Acid Derivatives as Xanthine Oxidase Inhibitors and Free Radical Scavengers.

    Science.gov (United States)

    Ali, Md Rahmat; Kumar, Suresh; Afzal, Obaid; Shalmali, Nishtha; Sharma, Manju; Bawa, Sandhya

    2016-04-01

    A series of 2-(substituted benzylamino)-4-methylthiazole-5-carboxylic acid was designed and synthesized as structural analogue of febuxostat. A methylene amine spacer was incorporated between the phenyl ring and thiazole ring in contrast to febuxostat in which the phenyl ring was directly linked with the thiazole moiety. The purpose of incorporating methylene amine was to provide a heteroatom which is expected to favour hydrogen bonding within the active site residues of the enzyme xanthine oxidase. The structure of all the compounds was established by the combined use of FT-IR, NMR and MS spectral data. All the compounds were screened in vitro for their ability to inhibit the enzyme xanthine oxidase as per the reported procedure along with DPPH free radical scavenging assay. Compounds 5j, 5k and 5l demonstrated satisfactory potent xanthine oxidase inhibitory activities with IC50 values, 3.6, 8.1 and 9.9 μm, respectively, whereas compounds 5k, 5n and 5p demonstrated moderate antioxidant activities having IC50 15.3, 17.6 and 19.6 μm, respectively, along with xanthine oxidase inhibitory activity. Compound 5k showed moderate xanthine oxidase inhibitory activity as compared with febuxostat along with antioxidant activity. All the compounds were also studied for their binding affinity in active site of enzyme (PDB ID-1N5X). © 2015 John Wiley & Sons A/S.

  2. THE USE OF CHLOROSULFONIC ACID ON SULFONATION OF cPTFE FILM GRAFTED STYRENE FOR PROTON EXCHANGE MEMBRANE

    Directory of Open Access Journals (Sweden)

    Yohan Yohan

    2010-06-01

    Full Text Available Sulfonation of g-ray iradiated and styrene-grafted crosslinked polytetrafluoro ethylene film (cPTFE-g-S film have been done. The aim of the research was to make hydrophyl membrane as proton exchange membrane fuel cell. Sulfonation was prepared by using chlorosulfonic acid in chloroethane under various conditions. The impact of the percentage of grafting, the concentration of chlorosulfonic acid, the reaction time,and the reaction temperature on the properties of sulfonated film were examined. The results show that sulfonation of surface-grafted films was incomplete at room temperature. Increasing concentration of chlorosulfonic acid and reaction temperature accelerate the reaction but they also favor side reactions. These lead to the decrease of the ion-exchange capacity, water uptake, and proton conductivity but the increase of the resistance to oxidation in a perhydrol solution. The resulted cPTFE-g-SS membraneis stabile in a H2O2 30% solution for 20 h.   Keywords: Chorosulfonic acid, sulfonation, PTFE film, proton excange membrane.

  3. Sulfone-stabilized carbanions for the reversible covalent capture of a posttranslationally-generated cysteine oxoform found in protein tyrosine phosphatase 1B (PTP1B).

    Science.gov (United States)

    Parsons, Zachary D; Ruddraraju, Kasi Viswanatharaju; Santo, Nicholas; Gates, Kent S

    2016-06-15

    Redox regulation of protein tyrosine phosphatase 1B (PTP1B) involves oxidative conversion of the active site cysteine thiolate into an electrophilic sulfenyl amide residue. Reduction of the sulfenyl amide by biological thiols regenerates the native cysteine residue. Here we explored fundamental chemical reactions that may enable covalent capture of the sulfenyl amide residue in oxidized PTP1B. Various sulfone-containing carbon acids were found to react readily with a model peptide sulfenyl amide via attack of the sulfonyl carbanion on the electrophilic sulfur center in the sulfenyl amide. Both the products and the rates of these reactions were characterized. The results suggest that capture of a peptide sulfenyl amide residue by sulfone-stabilized carbanions can slow, but not completely prevent, thiol-mediated generation of the corresponding cysteine-containing peptide. Sulfone-containing carbon acids may be useful components in the construction of agents that knock down PTP1B activity in cells via transient covalent capture of the sulfenyl amide oxoform generated during insulin signaling processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Effects of Greek legume plant extracts on xanthine oxidase, catalase and superoxide dismutase activities.

    Science.gov (United States)

    Spanou, Chrysoula I; Veskoukis, Aristidis S; Stagos, Dimitrios; Liadaki, Kalliopi; Aligiannis, Nectarios; Angelis, Apostolos; Skaltsounis, Alexios-Leandros; Anastasiadi, Maria; Haroutounian, Serkos A; Kouretas, Dimitrios

    2012-03-01

    Legumes are considered to have beneficial health implications, which have been attributed to their phytochemical content. Polyphenols are considered the most important phytochemical compounds extensively studied for their antioxidant properties. The aim of the present study was to examine the effects of potent antioxidant legume plant extracts on xanthine oxidase (XO), catalase (CAT) and superoxide dismutase (SOD) activities. XO exerts a dual role, as it is the major contributor of free radicals during exercise while it generates uric acid, the most potent antioxidant molecule in plasma. CAT and SOD are two of the main enzymes of the antioxidant defence of tissues. We demonstrate that the majority of the extracts inhibited XO activity, but they had no effect on CAT inhibition and SOD induction when used at low concentrations. These results imply that the tested extracts may be considered as possible source of novel XO inhibitors. However, we have shown that allopurinol administration, a known XO inhibitor, before exercise reduces performance and induces oxidative stress in rats. Considering the fact that the extracts examined had an inhibitory effect on XO activity, possibly posing a restriction in their characterization as antioxidants, phytochemical antioxidant administration before exercise should probably be reconsidered.

  5. 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

  6. 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)

  7. 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.

  8. Nitro-oleic acid ameliorates oxygen and glucose deprivation/re-oxygenation triggered oxidative stress in renal tubular cells via activation of Nrf2 and suppression of NADPH oxidase.

    Science.gov (United States)

    Nie, Huibin; Xue, Xia; Liu, Gang; Guan, Guangju; Liu, Haiying; Sun, Lina; Zhao, Long; Wang, Xueling; Chen, Zhixin

    2016-01-01

    Nitroalkene derivative of oleic acid (OA-NO 2 ), due to its ability to mediate revisable Michael addition, has been demonstrated to have various biological properties and become a therapeutic agent in various diseases. Though its antioxidant properties have been reported in different models of acute kidney injury (AKI), the mechanism by which OA-NO 2 attenuates intracellular oxidative stress is not well investigated. Here, we elucidated the anti-oxidative mechanism of OA-NO 2 in an in vitro model of renal ischemia/reperfusion (I/R) injury. Human tubular epithelial cells were subjected to oxygen and glucose deprivation/re-oxygenation (OGD/R) injury. Pretreatment with OA-NO 2 (1.25 μM, 45 min) attenuated OGD/R triggered reactive oxygen species (ROS) generation and subsequent mitochondrial membrane potential disruption. This action was mediated via up-regulating endogenous antioxidant defense components including superoxide dismutase (SOD1), heme oxygenase 1 (HO-1), and γ-glutamyl cysteine ligase modulatory subunits (GCLM). Moreover, subcellular fractionation analyses demonstrated that OA-NO 2 promoted nuclear translocation of nuclear factor-E2- related factor-2 (Nrf2) and Nrf2 siRNA partially abrogated these protective effects. In addition, OA-NO 2 inhibited NADPH oxidase activation and NADPH oxidase 4 (NOX4), NADPH oxidase 2 (NOX2) and p22 phox up-regulation after OGD/R injury, which was not relevant to Nrf2. These results contribute to clarify that the mechanism of OA-NO 2 reno-protection involves both inhibition of NADPH oxidase activity and induction of SOD1, Nrf2-dependent HO-1, and GCLM.

  9. Electronic Conductivity of Polypyrrole−Dodecyl Benzene Sulfonate Complexes

    DEFF Research Database (Denmark)

    West, Keld; Bay, Lasse; Nielsen, Martin Meedom

    2004-01-01

    The electronic conductivity of the electroactive polymer polypyrrole-dodecyl benzene sulfonate (PPy-DBS) has been characterized as function of the redox level. The polymer was synthesized with different isomers of the dopant anions: the common mixed DBS tenside and three well-defined synthetic...

  10. 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...

  11. Expression and Characterization of Glucose Oxidase from Aspergillus niger in Yarrowia lipolytica.

    Science.gov (United States)

    Khadivi Derakshan, Fatemeh; Darvishi, Farshad; Dezfulian, Mehrouz; Madzak, Catherine

    2017-08-01

    Glucose oxidase (GOX) is currently used in clinical, pharmaceutical, food and chemical industries. The aim of this study was expression and characterization of Aspergillus niger glucose oxidase gene in the yeast Yarrowia lipolytica. For the first time, the GOX gene of A. niger was successfully expressed in Y. lipolytica using a mono-integrative vector containing strong hybrid promoter and secretion signal. The highest total glucose oxidase activity was 370 U/L after 7 days of cultivation. An innovative method was used to cell wall disruption in current study, and it could be recommended to use for efficiently cell wall disruption of Y. lipolytica. Optimum pH and temperature for recombinant GOX activity were 5.5 and 37 °C, respectively. A single band with a molecular weight of 80 kDa similar to the native and pure form of A. niger GOX was observed for the recombinant GOX in SDS-PAGE analysis. Y. lipolytica is a suitable and efficient eukaryotic expression system to production of recombinant GOX in compered with other yeast expression systems and could be used to production of pure form of GOX for industrial applications.

  12. Nitric oxide production and monoamine oxidase activity in cancer patients during interferon-alpha therapy.

    Science.gov (United States)

    Fekkes, Durk; Van Gool, Arthur R; Bannink, Marjolein; Sleijfer, Stefan; Kruit, Wim H J; van der Holt, Bronno; Eggermont, Alexander M M; Hengeveld, Michiel W; Stoter, Gerrit

    2009-10-01

    Both increased and decreased nitric oxide (NO) synthesis have been reported in patients treated with interferon-alpha (IFN-alpha). Animal studies showed that IFN-alpha administration results in increased levels of biogenic amines, subsequent activation of monoamine oxidases (MAOs), and finally in a change in NO production due to the H(2)O(2) generated by MAOs. We examined the potential relationship between NO production in plasma and MAO-B activity in platelets of 43 cancer patients during 8 weeks of treatment with IFN-alpha. NO synthesis was quantitated by measuring both the ratio of citrulline and arginine (CIT/ARG-ratio) and total nitrite/nitrate (NOx) levels. Compared to baseline, MAO activity and NOx increased, while the CIT/ARG-ratio decreased. No associations were found between NOx, MAO and CIT/ARG-ratio. Only few associations were observed between changes in the biochemical parameters and changes in psychopathology induced by IFN-alpha, of which the association between changes in CIT and lassitude was the most consistent. The results suggest that peripheral NO production and MAO activity are unrelated to each other, and that peripheral changes in these biochemical parameters induced by IFN-alpha are unlikely to contribute to definite psychiatric disturbance.

  13. 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)

  14. Synthesis and Process Optimization of Electrospun PEEK-Sulfonated Nanofibers by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Carlo Boaretti

    2015-07-01

    Full Text Available In this study electrospun nanofibers of partially sulfonated polyether ether ketone have been produced as a preliminary step for a possible development of composite proton exchange membranes for fuel cells. Response surface methodology has been employed for the modelling and optimization of the electrospinning process, using a Box-Behnken design. The investigation, based on a second order polynomial model, has been focused on the analysis of the effect of both process (voltage, tip-to-collector distance, flow rate and material (sulfonation degree variables on the mean fiber diameter. The final model has been verified by a series of statistical tests on the residuals and validated by a comparison procedure of samples at different sulfonation degrees, realized according to optimized conditions, for the production of homogeneous thin nanofibers.

  15. Undoped poly (phenyl sulfone) for radiation detection

    International Nuclear Information System (INIS)

    Nakamura, Hidehito; Shirakawa, Yoshiyuki; Sato, Nobuhiro; Kitamura, Hisashi; Takahashi, Sentaro

    2015-01-01

    Undoped aromatic ring polymers are potential scintillation materials. Here, we characterise poly (phenyl sulfone) (PPSU) for radiation detection. The amber-coloured transparent resin emits bluish-white fluorescence with 390-nm maximum. It has an excitation maximum of 340 nm, and has a density of 1.29 g/cm 3 . The effective refractive index based on its emission spectrum is 1.75. The light yield is almost equal to that of poly (ethylene terephthalate), which is a transparent resin. These results demonstrate that PPSU can be used as a component substrate in polymer blends for altering optical characteristics. - Highlights: • Poly (phenyl sulfone) (PPSU) has suitable characteristics as a scintillation material. • PPSU is an amber-coloured transparent resin that emits bluish white fluorescence with 390-nm maximum. • The 1.75 effective refractive index over the emission spectrum is relatively high. • The light yield is 0.95 times that of poly (ethylene terephthalate), which is a transparent resin. • PPSU can potentially alter optical characteristics in polymer blends

  16. Tet1 oxidase regulates neuronal gene transcription, active DNA hydroxymethylation, object location memory, and threat recognition memory

    Directory of Open Access Journals (Sweden)

    Dinesh Kumar

    2015-10-01

    Full Text Available A dynamic equilibrium between DNA methylation and demethylation of neuronal activity-regulated genes is crucial for memory processes. However, the mechanisms underlying this equilibrium remain elusive. Tet1 oxidase has been shown to play a key role in the active DNA demethylation in the central nervous system. In this study, we used Tet1 gene knockout (Tet1KO mice to examine the involvement of Tet1 in memory consolidation and storage in the adult brain. We found that Tet1 ablation leads to altered expression of numerous neuronal activity-regulated genes, compensatory upregulation of active demethylation pathway genes, and upregulation of various epigenetic modifiers. Moreover, Tet1KO mice showed an enhancement in the consolidation and storage of threat recognition (cued and contextual fear conditioning and object location memories. We conclude that Tet1 plays a critical role in regulating neuronal transcription and in maintaining the epigenetic state of the brain associated with memory consolidation and storage.

  17. Partial sulfonation of PVdF-co-HFP: A preliminary study and characterization for application in direct methanol fuel cell

    International Nuclear Information System (INIS)

    Das, Suparna; Kumar, Piyush; Dutta, Kingshuk; Kundu, Patit Paban

    2014-01-01

    Highlights: • Synthesis of sulfonated PVdF-co-HFP by reacting with chlorosulfonic acid. • Maximum degree of sulfonation and best properties were obtained for 7 h reaction. • A maximum water uptake value of 20% was obtained. • A maximum IEC value of 0.42 meq g −1 was obtained. • A methanol permeability of 2.44 × 10 −7 cm 2 s −1 was obtained. - Abstract: Sulfonation of PVdF-co-HFP was conducted by treating the copolymer with chlorosulfonic acid. The efficiency of this sulfonated copolymer towards application as a polymer electrolyte membrane in direct methanol fuel cell (DMFC) was evaluated. For this purpose, we determined the thermal stability, water uptake, ion exchange capacity (IEC), methanol crossover, and proton conductivity of the prepared membranes as functions of duration and degree of sulfonation. The characteristic aromatic peaks obtained in the FT-IR spectra confirmed the successful sulfonation of PVdF-co-HFP. The effect of sulfonation on the semi-crystalline nature of pure PVdF-co-HFP was determined from XRD analysis. Water uptake results indicated that a sulfonation time of 7 h produced maximum water uptake value of about 20%, with a corresponding IEC and proton conductivity values of about 0.42 meq g −1 and 0.00375 S cm −1 respectively. The maximum current density was recorded to be 30 mA cm −2 at 0.2 V potential

  18. IR Laser Ablative Degradation of Poly(phenylene ether sulfone): Deposition of Films Containing Sulfone, Sulfoxide and Sulfide Groups

    Czech Academy of Sciences Publication Activity Database

    Blazevska-Gilev, J.; Bastl, Zdeněk; Šubrt, Jan; Stopka, Pavel; Pola, Josef

    2009-01-01

    Roč. 94, č. 2 (2009), s. 196-200 ISSN 0141-3910 R&D Projects: GA AV ČR IAA400720619 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40400503; CEZ:AV0Z40320502 Keywords : laser ablation * laser-induced degradation * poly(1,4-phenylene ether-sulfone) Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.154, year: 2009

  19. 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.

  20. Toxicity of pyrolysis gases from polyether sulfone

    Science.gov (United States)

    Hilado, C. J.; Olcomendy, E. M.

    1979-01-01

    A sample of polyether sulfone was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. Animal response times were relatively short at pyrolysis temperatures of 600 to 800 C, with death occurring within 6 min. The principal toxicant appeared to be a compound other than carbon monoxide.

  1. 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.

  2. 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

  3. Thermal and pH stabilities of partially purified polyphenol oxidase ...

    African Journals Online (AJOL)

    Dr. Paul Chidoka Chikezie

    2012-07-30

    Jul 30, 2012 ... indices of the two PPO extracts is summarized in Table. 1. At the end of the .... activity near neutral pH values (Jime´nez-Atie´nzar et al.,. 2004; Dogan and Dogan, 2004). ..... oxidase from white cherry fruit (Starks gold). GIDA.

  4. Treatment of two different water resources in desalination and microbial fuel cell processes by poly sulfone/Sulfonated poly ether ether ketone hybrid membrane

    International Nuclear Information System (INIS)

    Ghasemi, Mostafa; Wan Daud, Wan Ramli; Alam, Javed; Ilbeygi, Hamid; Sedighi, Mehdi; Ismail, Ahmad Fauzi; Yazdi, Mohammad H.; Aljlil, Saad A.

    2016-01-01

    The PS (Polysulfone)/SPEEK (sulfonated poly ether ether ketone) hybrid membranes were fabricated and modified with low and high DS (degrees of sulfonation) for the desalination of brackish water and proton exchange membrane in microbial fuel cell. The results illustrated that SPEEK has changed the morphology of membranes and increase their hydrophilicity. PS/SPEEK with lower DS (29%) had the rejection percentage of 62% for NaCl and 68% for MgSO_4; while it was 67% and 81% for PS/SPEEK (76%) at 4 bars. Furthermore, the water flux for PS at 10 bar was 12.41 L m"−"2 h"−"1. It was four times higher for PS/SPEEK (29%) which means 49.5 L m"−"2 h"−"1 and 13 times higher for PS/SPEEK (76%) with means 157.76 L m"−"2 h"−"1. However, in MFC (microbial fuel cell), the highest power production was 97.47 mW/m"2 by PS/SPEEK (29%) followed by 41.42 mW/m"2 for PS/SPEEK (76%), and 9.4 mW/m"2 for PS. This revealed that the sulfonation of PEEK (poly ether ether ketone) made it a better additive for PS for desalination, because it created a membrane with higher hydrophilicity, better pore size and better for salt rejection. Although for the separator, the degree of sulfonation was limited; otherwise it made a membrane to transfer some of the unwanted ions. - Highlights: • Fabrication of a composite membrane for desalination and MFC. • PS/SPEEK (76%) had the lowest contact angle (48.8) and highest hydrophilicity than PS and PS/SPEEK (29%). • PS/SPEEK (29%) was the best separator for use in MFC. • PS/SPEEK (76%) had the highest flux (61.3 L m"−"2 h"−"1) for desalination.

  5. 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 ...

  6. Exercise training protects against atherosclerotic risk factors through vascular NADPH oxidase, extracellular signal-regulated kinase 1/2 and stress-activated protein kinase/c-Jun N-terminal kinase downregulation in obese rats.

    Science.gov (United States)

    Touati, Sabeur; Montezano, Augusto C I; Meziri, Fayçal; Riva, Catherine; Touyz, Rhian M; Laurant, Pascal

    2015-02-01

    Exercise training reverses atherosclerotic risk factors associated with metabolic syndrome and obesity. The aim of the present study was to determine the molecular anti-inflammatory, anti-oxidative and anti-atherogenic effects in aorta from rats with high-fat diet-induced obesity. Male Sprague-Dawley rats were placed on a high-fat (HFD) or control (CD) diet for 12 weeks. The HFD rats were then divided into four groups: (i) sedentary HFD-fed rats (HFD-S); (ii) exercise trained (motor treadmill 5 days/week, 60 min/day, 12 weeks) HFD-fed rats (HFD-Ex); (iii) modified diet (HFD to CD) sedentary rats (HF/CD-S); and (iv) an exercise-trained modified diet group (HF/CD-Ex). Tissue levels of NADPH oxidase (activity and expression), NADPH oxidase (Nox) 1, Nox2, Nox4, p47(phox) , superoxide dismutase (SOD)-1, angiotensin AT1 and AT2 receptors, phosphorylated mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase (ERK) 1/2, stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK)) and vascular cell adhesion molecule-1 (VCAM-1) were determined in the aorta. Plasma cytokines (tumour necrosis factor (TNF)-α and interleukin (IL)-6) levels were also measured. Obesity was accompanied by increases in NADPH oxidase activity, p47(phox) translocation, Nox4 and VCAM-1 protein expression, MAPK (ERK1/2, SAPK/JNK) phosphorylation and plasma TNF-α and IL-6 levels. Exercise training and switching from the HFD to CD reversed almost all these molecular changes. In addition, training increased aortic SOD-1 protein expression and decreased ERK1/2 phosphorylation. These findings suggest that protective effects of exercise training on atherosclerotic risk factors induced by obesity are associated with downregulation of NADPH oxidase, ERK1/2 and SAPK/JNK activity and increased SOD-1 expression. © 2014 Wiley Publishing Asia Pty Ltd.

  7. Synthesis, crystal structures, fluorescence and xanthine oxidase inhibitory activity of pyrazole-based 1,3,4-oxadiazole derivatives

    Science.gov (United States)

    Qi, De-Qiang; Yu, Chuan-Ming; You, Jin-Zong; Yang, Guang-Hui; Wang, Xue-Jie; Zhang, Yi-Ping

    2015-11-01

    A series of pyrazole-based 1,3,4-oxadiazole derivatives were rationally designed and synthesized in good yields by following a convenient route. All the newly synthesized molecules were fully characterized by IR, 1H NMR and elemental analysis. Eight compounds were structurally determined by single crystal X-ray diffraction analysis. The fluorescence properties of all the compounds were investigated in dimethyl sulfoxide media. In addition, these newly synthesized compounds were evaluated for in vitro inhibitory activity against commercial enzyme xanthine oxidase (XO) by measuring the formation of uric acid from xanthine. Among the compounds synthesized and tested, 3d and 3e were found to be moderate inhibitory activity against commercial XO with IC50 = 72.4 μM and 75.6 μM. The studies gave a new insight in further optimization of pyrazole-based 1,3,4-oxadiazole derivatives with excellent fluorescence properties and XO inhibitory activity.

  8. Posttranslational ruling of xanthine oxidase activity in bovine milk by its substrates

    Energy Technology Data Exchange (ETDEWEB)

    Silanikove, Nissim [Ruminant Physiology, Institute of Animal Science, Agricultural Research Organization, Volcani Center, P.O. Box 6, Bet Dagan 50250 (Israel); Shapiro, Fira [Ruminant Physiology, Institute of Animal Science, Agricultural Research Organization, Volcani Center, P.O. Box 6, Bet Dagan 50250 (Israel); Leitner, Gabriel [National Mastitis Reference Center, Kimron Veterinary Institute, Bet Dagan 50250 (Israel)

    2007-11-23

    The aims of this study were to test the hypothesis that the substrates of xanthine oxidase (XO), xanthine and hypoxanthine, are consumed while the milk is stored in the gland between milkings, and to explore how XO activity responds to bacteria commonly associated with subclinical infections in the mammary gland. Freshly secreted milk was obtained following complete evacuation of the gland and induction of milk ejection with oxytocin. In bacteria-free fresh milk xanthine and hypoxanthine were converted to uric acid within 30 min (T{sub 1/2} {approx} 10 min), which in turn provides electrons for formation of hydrogen peroxide and endows the alveolar lumen with passive protection against invading bacteria. On the other hand, the longer residence time of milk in the cistern compartment was not associated with oxidative stress as a result of XO idleness caused by exhaustion of its physiological fuels. The specific response of XO to bacteria species and the resulting bacteria-dependent nitrosative stress further demonstrates that it is part of the gland immune system.

  9. Posttranslational ruling of xanthine oxidase activity in bovine milk by its substrates

    International Nuclear Information System (INIS)

    Silanikove, Nissim; Shapiro, Fira; Leitner, Gabriel

    2007-01-01

    The aims of this study were to test the hypothesis that the substrates of xanthine oxidase (XO), xanthine and hypoxanthine, are consumed while the milk is stored in the gland between milkings, and to explore how XO activity responds to bacteria commonly associated with subclinical infections in the mammary gland. Freshly secreted milk was obtained following complete evacuation of the gland and induction of milk ejection with oxytocin. In bacteria-free fresh milk xanthine and hypoxanthine were converted to uric acid within 30 min (T 1/2 ∼ 10 min), which in turn provides electrons for formation of hydrogen peroxide and endows the alveolar lumen with passive protection against invading bacteria. On the other hand, the longer residence time of milk in the cistern compartment was not associated with oxidative stress as a result of XO idleness caused by exhaustion of its physiological fuels. The specific response of XO to bacteria species and the resulting bacteria-dependent nitrosative stress further demonstrates that it is part of the gland immune system

  10. An investigation of proton conductivity of binary matrices sulfonated ...

    Indian Academy of Sciences (India)

    to their potential applications in proton exchange membrane fuel cells (PEMFCs) ... is highly sulfonated and has high water uptake property.11,12 The proton conductivity ... SPSU membranes have lower gas permeability and liquid. (water and ...

  11. Improving the Conductivity of Sulfonated Polyimides as Proton Exchange Membranes by Doping of a Protic Ionic Liquid

    Directory of Open Access Journals (Sweden)

    Bor-Kuan Chen

    2014-10-01

    Full Text Available Proton exchange membranes (PEMs are a key component of a proton exchange membrane fuel cell. Sulfonated polyimides (SPIs were doped by protic ionic liquid (PIL to prepare composite PEMs with substantially improved conductivity. SPIs were synthesized from diamine, 2,2-bis[4-(4-amino-phenoxyphenyl]propane (BAPP, sulfonated diamine, 4,4'-diamino diphenyl ether-2,2'-disulfonic acid (ODADS and aromatic anhydride. BAPP improved the mechanical and thermal properties of SPIs, while ODADS enhanced conductivity. A PIL, 1-vinylimidazolium trifluoromethane-sulfonate ([VIm][OTf], was utilized. [VIm][OTf] offered better conductivity, which can be attributed to its vinyl chemical structure attached to an imidazolium ring that contributed to ionomer-PIL interactions. We prepared sulfonated polyimide/ionic liquid (SPI/IL composite PEMs using 50 wt% [VIm][OTf] with a conductivity of 7.17 mS/cm at 100 °C, and in an anhydrous condition, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride (DSDA was used in the synthesis of SPIs, leading to several hundred-times improvement in conductivity compared to pristine SPIs.

  12. Development of 1-Amino-4-(phenylamino)anthraquinone-2-sulfonate Sodium Derivatives as a New Class of Inhibitors of RANKL-Induced Osteoclastogenesis.

    Science.gov (United States)

    Lee, Chia-Chung; Chen, Chun-Liang; Liu, Fei-Lan; Chiou, Chung-Yu; Chen, Tsung-Chih; Wu, Cheng-Chi; Sun, Wei-Hsin; Chang, Deh-Ming; Huang, Hsu-Shan

    2016-05-01

    A series of 1-amino-4-(phenylamino)anthraquinone-2-sulfonate sodium derivatives was synthesized and evaluated for osteoclast inhibition using a TRAP-staining assay. Among them, two compounds, LCCY-13 and LCCY-15, dose-dependently suppressed receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation. Moreover, the cytotoxicity assay on RAW264.7 cells suggested that the inhibition of osteoclastic bone resorption by these compounds was not a result of their cytotoxicity. Further, the inhibitory activities of compounds LCCY-13 and LCCY-15 were further confirmed by including specific inhibition of NFATc1 expression levels in nuclei using an immunofluorescent analysis. In addition, LCCY-13 and LCCY-15 also significantly attenuated the bone resorption activity of osteoclasts according to a pit formation assay. Thus, a new class of 1-amino-4-(phenylamino)anthraquinone-2-sulfonate sodium compounds might be considered as an essential lead structure for the further development of anti-resorptive agents. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Depletion of rat cortical norepinephrine and the inhibition of [3H]norepinephrine uptake by xylamine does not require monoamine oxidase activity

    International Nuclear Information System (INIS)

    Dudley, M.W.

    1988-01-01

    Inhibition of monoamine oxidase A through pretreatment of rats with clorgyline or the pro-drug MDL 72,394 did not block the amine-depleting action of xylamine. Xylamine treatment resulted in a loss of approximately 60% of the control level of norepinephrine in the cerebral cortex. A 1-hr pretreatment, but not a 24-hr pretreatment, with the monoamine oxidase B inhibitor, L-deprenyl, prevented the depletion of norepinephrine by xylamine. In addition, pretreatment with MDL 72,974, a monoamine oxidase B inhibitor without amine-releasing or uptake - inhibiting effects, did not prevent cortical norepinephrine levels. Inhibition of monoamine oxidase by either MDL 72,974 or MDL 72,394 did not prevent the inhibition of [ 3 H]norepinephrine uptake into rat cortical synaptosomes by xylamine. These data indicate that monoamine oxidase does not mediate the amine-releasing or uptake inhibiting properties of xylamine. The protection afforded by L-deprenyl following a 1-hr pretreatment most probably was due to accumulation of its metabolite, L-amphetamine, which would inhibit the uptake carrier. A functional carrier is required for depletion since desipramine administered 1 hr prior to xylamine, was also able to prevent depletion of norepinephrine

  14. Exposure to GSM 900 MHz electromagnetic fields affects cerebral cytochrome c oxidase activity

    International Nuclear Information System (INIS)

    Ammari, Mohamed; Lecomte, Anthony; Sakly, Mohsen; Abdelmelek, Hafedh; Seze, Rene de

    2008-01-01

    The world-wide and rapidly growing use of mobile phones has raised serious concerns about the biological and health-related effects of radio frequency (RF) radiation, particularly concerns about the effects of RFs upon the nervous system. The goal of this study was conducted to measure cytochrome oxidase (CO) levels using histochemical methods in order to evaluate regional brain metabolic activity in rat brain after exposure to a GSM 900 MHz signal for 45 min/day at a brain-averaged specific absorption rate (SAR) of 1.5 W/Kg or for 15 min/day at a SAR of 6 W/Kg over seven days. Compared to the sham and control cage groups, rats exposed to a GSM signal at 6 W/Kg showed decreased CO activity in some areas of the prefrontal and frontal cortex (infralimbic cortex, prelimbic cortex, primary motor cortex, secondary motor cortex, anterior cingulate cortex areas 1 and 2 (Cg1 and Cg2)), the septum (dorsal and ventral parts of the lateral septal nucleus), the hippocampus (dorsal field CA1, CA2 and CA3 of the hippocampus and dental gyrus) and the posterior cortex (retrosplenial agranular cortex, primary and secondary visual cortex, perirhinal cortex and lateral entorhinal cortex). However, the exposure to GSM at 1.5 W/Kg did not affect brain activity. Our results indicate that 6 W/Kg GSM 900 MHz microwaves may affect brain metabolism and neuronal activity in rats

  15. 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.

  16. Effect of sodium aromatic sulfonate group in anionic polymer dispersant on the viscosity of coal-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Toshio Kakui; Hidehiro Kamiya [Lion Corporation, Tokyo (Japan). Chemicals Research Laboratories, Chemicals Division

    2004-06-01

    This paper focused on the effect of sodium aromatic sulfonate in anionic polymer dispersants on the viscosity of coal-water mixtures (CWMs) with a Tatung coal powder. To determine the optimum molecular structure of a polymer dispersant for the minimum viscosity of a CWM, various anionic co-polymers with different hydrophilic and hydrophobic groups or different molecular weights were prepared, using various types of monomers. Anionic co-polymers with sodium aromatic sulfonate, such as sodium styrene-sulfonate and sodium naphthalene-sulfonate, reduced the viscosity of dense CWMs. In particular, a co-polymer of sodium styrene-sulfonate and sodium acrylate with a molar ratio of 70:30 and a molecular weight of {approximately} 10 000 gave the minimum viscosity of a 70 wt % CWM. To obtain a low viscosity for a CWM, a large electrostatic repulsive force with an absolute value of the zeta potential of the coal particles of {gt} 70 mV and {gt} 6.5 mg/g of adsorbed polymer on the coal surface were needed. The mixture of sodium polystyrene-sulfonate and sodium polyacrylate with a weight ratio of 50:50 also gave a low viscosity of 70 wt % CWM. On the basis of the results, the adsorption behavior of polymer dispersants on the coal surface is examined by measuring the wettability of coal powder pellets. 27 refs., 8 figs., 3 tabs.

  17. 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.

  18. Khz-cp (crude polysaccharide extract obtained from the fusion of Ganoderma lucidum and Polyporus umbellatus mycelia) induces apoptosis by increasing intracellular calcium levels and activating P38 and NADPH oxidase-dependent generation of reactive oxygen species in SNU-1 cells.

    Science.gov (United States)

    Kim, Tae Hwan; Kim, Ju Sung; Kim, Zoo Haye; Huang, Ren Bin; Chae, Young Lye; Wang, Ren Sheng

    2014-07-10

    Khz-cp is a crude polysaccharide extract that is obtained after nuclear fusion in Ganoderma lucidum and Polyporus umbellatus mycelia (Khz). It inhibits the growth of cancer cells. Khz-cp was extracted by solvent extraction. The anti-proliferative activity of Khz-cp was confirmed by using Annexin-V/PI-flow cytometry analysis. Intracellular calcium increase and measurement of intracellular reactive oxygen species (ROS) were performed by using flow cytometry and inverted microscope. SNU-1 cells were treated with p38, Bcl-2 and Nox family siRNA. siRNA transfected cells was employed to investigate the expression of apoptotic, growth and survival genes in SNU-1 cells. Western blot analysis was performed to confirm the expression of the genes. In the present study, Khz-cp induced apoptosis preferentially in transformed cells and had only minimal effects on non-transformed cells. Furthermore, Khz-cp was found to induce apoptosis by increasing the intracellular Ca2+ concentration ([Ca2+]i) and activating P38 to generate reactive oxygen species (ROS) via NADPH oxidase and the mitochondria. Khz-cp-induced apoptosis was caspase dependent and occurred via a mitochondrial pathway. ROS generation by NADPH oxidase was critical for Khz-cp-induced apoptosis, and although mitochondrial ROS production was also required, it appeared to occur secondary to ROS generation by NADPH oxidase. Activation of NADPH oxidase was shown by the translocation of the regulatory subunits p47phox and p67phox to the cell membrane and was necessary for ROS generation by Khz-cp. Khz-cp triggered a rapid and sustained increase in [Ca2+]i that activated P38. P38 was considered to play a key role in the activation of NADPH oxidase because inhibition of its expression or activity abrogated membrane translocation of the p47phox and p67phox subunits and ROS generation. In summary, these data indicate that Khz-cp preferentially induces apoptosis in cancer cells and that the signaling mechanisms involve an

  19. Synthesis and characterization of sulfonated polyesters derived from glycerol; Sintese e caracterizacao de poliesteres sulfonados obtidos a partir do glicerol

    Energy Technology Data Exchange (ETDEWEB)

    Fiuza, R.A.; Jose, N.M.; Boaventura, J.S. [Universidade Federal da Bahia (IQ/UFBA), Salvador, BA (Brazil). Inst. de Quimica; Fiuza, R.P. [Universidade Federal da Bahia (EP/UFBA), Salvador, BA (Brazil). Escola Politecnica. Curso de Mestrado em Engenharia Quimica

    2010-07-01

    In this work were synthesized polyesters from glycerol and acid sulfonated phthalic previously. The materials were characterized by DSC, TGA, FTIR, SEM, XRD and XRF. The results showed effective sulfonation of phthalic acid. The presence of sulfonic groups promoted strong changes in the crystallinity of the new material makes the lens. The polyesters made from phthalic acid sulfonated combine characteristics such as heat resistance and groups that drivers potentiate the electrolyte for application in fuel cells proton exchange membrane and also for gas separation. (author)

  20. A Plastid Terminal Oxidase Associated with Carotenoid Desaturation during Chromoplast Differentiation1

    Science.gov (United States)

    Josse, Eve-Marie; Simkin, Andrew J.; Gaffé, Joël; Labouré, Anne-Marie; Kuntz, Marcel; Carol, Pierre

    2000-01-01

    The Arabidopsis IMMUTANS gene encodes a plastid homolog of the mitochondrial alternative oxidase, which is associated with phytoene desaturation. Upon expression in Escherichia coli, this protein confers a detectable cyanide-resistant electron transport to isolated membranes. In this assay this activity is sensitive to n-propyl-gallate, an inhibitor of the alternative oxidase. This protein appears to be a plastid terminal oxidase (PTOX) that is functionally equivalent to a quinol:oxygen oxidoreductase. This protein was immunodetected in achlorophyllous pepper (Capsicum annuum) chromoplast membranes, and a corresponding cDNA was cloned from pepper and tomato (Lycopersicum esculentum) fruits. Genomic analysis suggests the presence of a single gene in these organisms, the expression of which parallels phytoene desaturase and ζ-carotene desaturase gene expression during fruit ripening. Furthermore, this PTOX gene is impaired in the tomato ghost mutant, which accumulates phytoene in leaves and fruits. These data show that PTOX also participates in carotenoid desaturation in chromoplasts in addition to its role during early chloroplast development. PMID:10938359

  1. Brain region-specific perfluoroalkylated sulfonate (PFSA) and carboxylic acid (PFCA) accumulation and neurochemical biomarker responses in east Greenland polar bears (Ursus maritimus).

    Science.gov (United States)

    Eggers Pedersen, Kathrine; Basu, Niladri; Letcher, Robert; Greaves, Alana K; Sonne, Christian; Dietz, Rune; Styrishave, Bjarne

    2015-04-01

    Perfluoroalkyl substances (PFASs) is a growing class of contaminants in the Arctic environment, and include the established perfluorinated sulfonates (PFSAs; especially perfluorooctane sulfonate (PFOS)) and carboxylic acids (PFCAs). PFSAs and PFCAs of varying chain length have been reported to bioaccumulate in lipid rich tissues of the brain among other tissues such as liver, and can reach high concentrations in top predators including the polar bear. PFCA and PFSA bioaccummulation in the brain has the potential to pose neurotoxic effects and therefore we conducted a study to investigate if variations in neurochemical transmitter systems i.e. the cholinergic, glutaminergic, dopaminergic and GABAergic, could be related to brain-specific bioaccumulation of PFASs in East Greenland polar bears. Nine brain regions from nine polar bears were analyzed for enzyme activity (monoamine oxidase (MAO), acetylcholinesterase (AChE) and glutamine synthetase (GS)) and receptor density (dopamine-2 (D2), muscarinic cholinergic (mAChR) and gamma-butyric acid type A (GABA-A)) along with PFSA and PFCA concentrations. Average brain ∑PFSA concentration was 25ng/g ww where PFOS accounted for 91%. Average ∑PFCA concentration was 88ng/g ww where PFUnDA, PFDoDA and PFTrDA combined accounted for 79%. The highest concentrations of PFASs were measured in brain stem, cerebellum and hippocampus. Correlative analyses were performed both across and within brain regions. Significant positive correlations were found between PFASs and MAO activity in occipital lobe (e.g. ∑PFCA; rp=0.83, p=0.041, n=6) and across brain regions (e.g. ∑PFCA; rp=0.47, p=0.001, ∑PFSA; rp=0.44, p>0.001; n=50). GABA-A receptor density was positively correlated with two PFASs across brain regions (PFOS; rp=0.33, p=0.02 and PFDoDA; rp=0.34, p=0.014; n=52). Significant negative correlations were found between mAChR density and PFASs in cerebellum (e.g. ∑PFCA; rp=-0.95, p=0.013, n=5) and across brain regions (e.g.

  2. 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....

  3. Crystallization and preliminary X-ray analysis of Aspergillus oryzae catechol oxidase

    International Nuclear Information System (INIS)

    Kaljunen, Heidi; Gasparetti, Chiara; Kruus, Kristiina; Rouvinen, Juha; Hakulinen, Nina

    2011-01-01

    Catechol oxidase from A. oryzae was crystallized by the hanging-drop vapour-diffusion method. Catechol oxidase is an enzyme that catalyzes the oxidation of o-diphenols to the corresponding o-quinones. It is a copper-containing enzyme with a binuclear copper active site. Here, the crystallization and multiple-wavelength anomalous dispersion data collection of catechol oxidase from the mould fungus Aspergillus oryzae are described. During the purification, three forms of the enzyme (39.3, 40.5 and 44.3 kDa) were obtained. A mixture of these three forms was initially crystallized and gave crystals that diffracted to 2.5 Å resolution and belonged to space group P3 2 21, with unit-cell parameters a = b = 118.9, c = 84.5 Å, α = β = 90, γ = 120°. A preparation containing only the shorter form (39.3 kDa) produced crystals that diffracted to 2.9 Å resolution and belonged to space group P2 1 2 1 2 1 , with unit-cell parameters a = 51.8, b = 95.3, c = 139.5 Å, α = β = γ = 90°

  4. Sulfonic-based precursors (SAPs for silica mesostructures: Advances in synthesis and applications

    Directory of Open Access Journals (Sweden)

    Sadegh Rostamnia*

    2016-01-01

    Full Text Available Sulfonic acid-based precursors (SAP play an important role in tailoring mesoporous silica’s and convert them to a solid acid catalyst with a Bronsted-type nature. These kinds of solid acids contribute to sustainable and green chemistry by their heterogeneous, recyclable, and high efficiency features. Therefore, knowing the properties and reactivity of SAPs can guide us to manufacture a sulfonated mesostructures compatible with reaction type and conditions. In the present review, some of the important SAPs, their reactivity and mechanism of functionalization are discussed.

  5. Synthesis and ATRP of novel fluorinated aromatic monomer with pendant sulfonate group

    DEFF Research Database (Denmark)

    Dimitrov, Ivaylo; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    Novel, fluorinated monomer with pendant sulfonate group was synthesized utilizing a two-step derivatization of 2,3,4,5,6-pentafluorostyrene (FS). The first step was a nucleophilic substitution of the fluorine atom in para position by hydroxyl group followed by sulfopropylation. The monomer...... was polymerized under aqueous ATRP conditions to yield phenyl-fluorinated aromatic homopolymer bearing pendant sulfonates on each repeating unit. Furthermore, this polymer was used as macroinitiator for the ATRP of poly(ethylene glycol) methacrylate. The polymers were characterized by 1H NMR, SEC and FTIR...

  6. Perfluorooctane sulfonate adsorption on powder activated carbon: Effect of phosphate (P) competition, pH, and temperature.

    Science.gov (United States)

    Qian, Jin; Shen, Mengmeng; Wang, Peifang; Wang, Chao; Li, Kun; Liu, Jingjing; Lu, Bianhe; Tian, Xin

    2017-09-01

    Powdered activated carbon (PAC), as an adsorbent, was applied to remove perfluorooctane sulfonate (PFOS) from aqueous solution. Laboratory batch experiments were performed to investigate the influences of phosphate (P) competition, temperature, and pH for PFOS adsorption onto PAC. The results showed that higher temperature favored PFOS adsorption in single and binary systems. The kinetic data fitted very well to the pseudo second-order kinetic model. Thermodynamically, the endothermic enthalpy of the PFOS adsorption in single and binary systems were 125.07 and 21.25 kJ mol -1 , respectively. The entropy of the PFOS adsorption in single and binary systems were 0.479 and 0.092 kJ mol -1  K -1 , respectively. And the Gibbs constants were negative. These results indicated that the adsorption processes were spontaneous. The adsorption isotherms of PFOS agreed well with the Langmuir model. In the single system, PFOS adsorption decreased with increased pH value. The difference in the amount of PFOS adsorption between the single and binary systems increased at higher pH. Frustrated total internal reflection (FTIR) demonstrated that P competition increased the hydrophilicity of the PAC and the electrostatic repulsion between PFOS and PAC, then the PFOS adsorption amount decreased. It also demonstrated that, at higher temperature, increased PFOS adsorption was mainly due to the higher diffusion rate of PFOS molecules and greater number of active sites opened on the PAC surface. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Effect of retinal impulse blockage on cytochrome oxidase-poor interpuffs in the macaque striate cortex: quantitative EM analysis of neurons.

    Science.gov (United States)

    Wong-Riley, M T; Trusk, T C; Kaboord, W; Huang, Z

    1994-09-01

    One of the hallmarks of the primate striate cortex is the presence of cytochrome oxidase-rich puffs in its supragranular layers. Neurons in puffs have been classified as type A, B, and C in ascending order of cytochrome oxidase content, with type C cells being the most vulnerable to retinal impulse blockade. The present study aimed at analysing cytochrome oxidase-poor interpuffs with reference to their metabolic cell types and the effect of intraretinal tetrodotoxin treatment. The same three metabolic types were found in interpuffs, except that type B and C neurons were smaller and less cytochrome oxidase-reactive in interpuffs than in puffs. Type A neurons had small perikarya, low levels of cytochrome oxidase, and received exclusively symmetric axosomatic synapses. The largest neurons were pyramidal, type B cells with moderate cytochrome oxidase activity and were also contacted exclusively by symmetric axosomatic synapses. Type C cells medium-sized with a rich supply of large, darkly reactive mitochondria and possessed all the characteristics of GABAergic neurons. They were the only cell type that received both symmetric and asymmetric axosomatic synapses. Two weeks of monocular tetrodotoxin blockade in adult monkeys caused all three major cell types in deprived interpuffs to suffer a significant downward shift in the size and cytochrome oxidase reactivity of their mitochondria, but the effects were more severe in type B and C neurons. In nondeprived interpuffs, all three cell types gained both in size and absolute number of mitochondria, and type A cells also had an elevated level of cytochrome oxidase, indicating that they might be functioning at a competitive advantage over cells in deprived columns. However, type B and C neurons showed a net loss of darkly reactive mitochondria, indicating that these cells became less active. Thus, mature interpuff neurons remained vulnerable to retinal impulse blockade and the metabolic capacity of these cells remains tightly

  8. Isolation and Characterization of the 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) Radical Cation-Scavenging Reaction Products of Arbutin.

    Science.gov (United States)

    Tai, Akihiro; Ohno, Asako; Ito, Hideyuki

    2016-09-28

    Arbutin, a glucoside of hydroquinone, has shown strong 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation-scavenging activity, especially in reaction stoichiometry. This study investigated the reaction mechanism of arbutin against ABTS radical cation that caused high stoichiometry of arbutin in an ABTS radical cation-scavenging assay. HPLC analysis of the reaction mixture of arbutin and ABTS radical cation indicated the existence of two reaction products. The two reaction products were purified and identified to be a covalent adduct of arbutin with an ABTS degradation fragment and 3-ethyl-6-sulfonate benzothiazolone. A time-course study of the radical-scavenging reactions of arbutin and the two reaction products suggested that one molecule of arbutin scavenges three ABTS radical cation molecules to generate an arbutin-ABTS fragment adduct as a final reaction product. The results suggest that one molecule of arbutin reduced two ABTS radical cation molecules to ABTS and then cleaved the third ABTS radical cation molecule to generate two products, an arbutin-ABTS fragment adduct and 3-ethyl-6-sulfonate benzothiazolone.

  9. The host cell sulfonation pathway contributes to retroviral infection at a step coincident with provirus establishment.

    Directory of Open Access Journals (Sweden)

    James W Bruce

    2008-11-01

    Full Text Available The early steps of retrovirus replication leading up to provirus establishment are highly dependent on cellular processes and represent a time when the virus is particularly vulnerable to antivirals and host defense mechanisms. However, the roles played by cellular factors are only partially understood. To identify cellular processes that participate in these critical steps, we employed a high volume screening of insertionally mutagenized somatic cells using a murine leukemia virus (MLV vector. This approach identified a role for 3'-phosphoadenosine 5'-phosphosulfate synthase 1 (PAPSS1, one of two enzymes that synthesize PAPS, the high energy sulfate donor used in all sulfonation reactions catalyzed by cellular sulfotransferases. The role of the cellular sulfonation pathway was confirmed using chemical inhibitors of PAPS synthases and cellular sulfotransferases. The requirement for sulfonation was mapped to a stage during or shortly after MLV provirus establishment and influenced subsequent gene expression from the viral long terminal repeat (LTR promoter. Infection of cells by an HIV vector was also shown to be highly dependent on the cellular sulfonation pathway. These studies have uncovered a heretofore unknown regulatory step of retroviral replication, have defined a new biological function for sulfonation in nuclear gene expression, and provide a potentially valuable new target for HIV/AIDS therapy.

  10. Bis-sulfonic Acid Ionic Liquids for the Conversion of Fructose to 5-Hydroxymethyl-2-furfural

    Directory of Open Access Journals (Sweden)

    Sangho Koo

    2012-10-01

    Full Text Available Homogenous bis-sulfonic acid ionic liquids (1 mol equiv. in DMSO (10 mol equiv. at 100 °C efficiently mediated the conversion of D-fructose into 5-hydroxymethyl-2-furfural in 75% isolated yield, which was roughly a 10% increment compared to the case of the mono-sulfonic acid ionic liquids.

  11. 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.

  12. Synthesis and properties of sulfonated copoly(phthalazinone ether imides) as electrolyte membranes in fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Pan Haiyan [Department of Polymer Science and Materials, Dalian University of Technology, Dalian 116012 (China); Institute of Functional Polymers, School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Zhu Xiuling, E-mail: zhuxl@dlut.edu.c [Department of Polymer Science and Materials, Dalian University of Technology, Dalian 116012 (China); Jian Xigao [Department of Polymer Science and Materials, Dalian University of Technology, Dalian 116012 (China)

    2010-01-01

    A new series of six-member sulfonated copolyimides (SPIs) were prepared by one-step solution copolycondensation from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 1,2-dihydro-2-(4-amino-2-sulfophenyl)-4- [4-(4-amino-2-sulfonphenoxy)-phenyl] (2H)phthalazin-1-one (S-DHPZDA), 4,4'-bis(4-aminophenoxy) biphenyl (BAPB) and 1,2-dihydro-2-(4-aminophenyl)-4-[4-(4-(aminophenoxyl)phenyl)] (2H)phthalazin-1-one (DHPZDA). The sulfonation degree (DS) of the SPIs was controlled by the mol ratio of the sulfonated diamine and non-sulfonated diamine. The obtained SPI membranes had excellent thermal stability, high mechanical property and proton conductivity as well as low methanol permeability. The tensile strength of the SPI membranes was ranging from 54.7 to 98.1 MPa, which was much higher than that of Nafion. The SPI membranes exhibited high proton conductivity (sigma) and low methanol permeability ranged from 10{sup -3} to 10{sup -2} S/cm and 10{sup -8} to 10{sup -7} cm{sup 2}/s depending on the DS of the polymers, respectively.

  13. Effect of degree of sulfonation and casting solvent on sulfonated poly(ether ether ketone) membrane for vanadium redox flow battery

    Science.gov (United States)

    Xi, Jingyu; Li, Zhaohua; Yu, Lihong; Yin, Bibo; Wang, Lei; Liu, Le; Qiu, Xinping; Chen, Liquan

    2015-07-01

    The properties of sulfonated poly(ether ether ketone) (SPEEK) membranes with various degree of sulfonation (DS) and casting solvent are investigated for vanadium redox flow battery (VRFB). The optimum DS of SPEEK membrane is firstly confirmed by various characterizations such as physicochemical properties, ion selectivity, and VRFB single-cell performance. Subsequently the optimum casting solvent is selected for the optimum DS SPEEK membrane within N,N‧-dimethylformamide (DMF), N,N‧-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and dimethylsulfoxide (DMSO). The different performance of SPEEK membranes prepared with various casting solvents can be attributed to the different interaction between solvent and -SO3H group of SPEEK. In the VRFB single-cell test, the optimum SPEEK membrane with DS of 67% and casting solvent of DMF (S67-DMF membrane) exhibits higher VRFB efficiencies and better cycle-life performance at 80 mA cm-2. The investigation of various DS and casting solvent will be effective guidance on the selection and modification of SPEEK membrane towards VRFB application.

  14. Glucose Oxidase Adsorption on Sequential Adsorbed Polyelectrolyte Films Studied by Spectroscopic Techniques

    Science.gov (United States)

    Tristán, Ferdinando; Solís, Araceli; Palestino, Gabriela; Gergely, Csilla; Cuisinier, Frédéric; Pérez, Elías

    2005-04-01

    The adsorption of Glucose Oxidase (GOX) on layers of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) deposited on Sequentially Adsorbed Polyelectrolyte Films (SAPFs) were studied by three different spectroscopic techniques. These techniques are: Optical Wave Light Spectroscopy (OWLS) to measure surface density; Fluorescence Resonance Energy Transfer (FRET) to verify the adsorption of GOX on the surface; and Fourier Transform Infrared Spectroscopy in Attenuated Total Reflection mode (FTIR-HATR) to inspect local structure of polyelectrolytes and GOX. Two positive and two negative polyelectrolytes are used: Cationic poly(ethyleneimine) (PEI) and poly(allylamine hydrochloride) (PAH) and anionic poly(sodium 4-styrene sulfonate) (PSS) and poly(acrylic acid) (PAA). These spectroscopic techniques do not require any labeling for GOX or SAPFs, specifically GOX and PSS are naturally fluorescent and are used as a couple donor-acceptor for the FRET technique. The SAPFs are formed by a (PEI)-(PSS/PAH)2 film followed by (PAA/PAH)n bilayers. GOX is finally deposited on top of SAPFs at different values of n (n=1..5). Our results show that GOX is adsorbed on positive ended SAPFs forming a monolayer. Contrary, GOX adsorption is not observed on negative ended film polyelectrolyte. GOX stability was tested adding a positive and a negative polyelectrolyte after GOX adsorption. Protein is partially removed by PAH and PAA, with lesser force by PAA.

  15. Isolation and Characterization of a Catabolite Repression-Insensitive Mutant of a Methanol Yeast, Candida boidinii A5, Producing Alcohol Oxidase in Glucose-Containing Medium

    OpenAIRE

    Sakai, Yasuyoshi; Sawai, Tohru; Tani, Yoshiki

    1987-01-01

    Mutants exhibiting alcohol oxidase (EC 1.1.3.13) activity when grown on glucose in the presence of methanol were found among 2-deoxyglucose-resistant mutants derived from a methanol yeast, Candida boidinii A5. One of these mutants, strain ADU-15, showed the highest alcohol oxidase activity in glucose-containing medium. The growth characteristics and also the induction and degradation of alcohol oxidase were compared with the parent strain and mutant strain ADU-15. In the parent strain, initia...

  16. Toxicokinetics of perfluorooctane sulfonate in rainbow trout (Oncorhynchus mykiss)

    Science.gov (United States)

    Rainbow trout (Oncorhynchus mykiss) confined to respirometer-metabolism chambers were dosed with perfluorooctane sulfonate (PFOS) by intra-arterial injection and sampled to obtain concentration time-course data for plasma, and either urine or expired water. The data were then an...

  17. Sulfite oxidase activity of cytochrome c: Role of hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Murugesan Velayutham

    2016-03-01

    Full Text Available In humans, sulfite is generated endogenously by the metabolism of sulfur containing amino acids such as methionine and cysteine. Sulfite is also formed from exposure to sulfur dioxide, one of the major environmental pollutants. Sulfite is used as an antioxidant and preservative in dried fruits, vegetables, and beverages such as wine. Sulfite is also used as a stabilizer in many drugs. Sulfite toxicity has been associated with allergic reactions characterized by sulfite sensitivity, asthma, and anaphylactic shock. Sulfite is also toxic to neurons and cardiovascular cells. Recent studies suggest that the cytotoxicity of sulfite is mediated by free radicals; however, molecular mechanisms involved in sulfite toxicity are not fully understood. Cytochrome c (cyt c is known to participate in mitochondrial respiration and has antioxidant and peroxidase activities. Studies were performed to understand the related mechanism of oxidation of sulfite and radical generation by ferric cytochrome c (Fe3+cyt c in the absence and presence of H2O2. Electron paramagnetic resonance (EPR spin trapping studies using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO were performed with sulfite, Fe3+cyt c, and H2O2. An EPR spectrum corresponding to the sulfite radical adducts of DMPO (DMPO-SO3- was obtained. The amount of DMPO-SO3- formed from the oxidation of sulfite by the Fe3+cyt c increased with sulfite concentration. In addition, the amount of DMPO-SO3- formed by the peroxidase activity of Fe3+cyt c also increased with sulfite and H2O2 concentration. From these results, we propose a mechanism in which the Fe3+cyt c and its peroxidase activity oxidizes sulfite to sulfite radical. Our results suggest that Fe3+cyt c could have a novel role in the deleterious effects of sulfite in biological systems due to increased production of sulfite radical. It also shows that the increased production of sulfite radical may be responsible for neurotoxicity and some of the injuries which

  18. Expression analysis of polyphenol oxidase isozymes by active staining method and tissue browning of head lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Noda, Takahiro; Iimure, Kazuhiko; Okamoto, Shunsuke; Saito, Akira

    2017-08-01

    Browning of plant tissue is generally considered attributable to enzymatic oxidation by polyphenol oxidase (PPO). Electrophoresis followed by activity staining has been used as an effective procedure to visually detect and isolate isozymes; however, it has not been applied for examination of various PPO isozymes in lettuce. Our study demonstrated that different lettuce PPO isozymes could be detected at different pH in active staining, and multiple isozymes were detected only under alkaline conditions. As a result, we concluded that activity staining with approximately pH 8 enabled to detect various PPO isozymes in lettuce. By expression analysis of the PPO isozymes after wounding, PPO isozymes that correlated with time-course of tissue browning were detected. The wound-induced PPO may play a key role in enzymatic browning.

  19. Erv2p: characterization of the redox behavior of a yeast sulfhydryl oxidase

    DEFF Research Database (Denmark)

    Wang, Wenzhong; Winther, Jakob R; Thorpe, Colin

    2007-01-01

    centers that facilitate the transfer of reducing equivalents from the dithiol substrates of these oxidases to the isoalloxazine ring where the reaction with molecular oxygen occurs. The present study examines yeast Erv2p and compares the redox behavior of this ER luminal protein with the augmenter...... and with unfolded proteins. Rapid reaction studies confirm that reduction of the flavin center of Erv2p is rate-limiting during turnover with molecular oxygen. This comparison of the redox properties between members of the ERV/ALR family of sulfhydryl oxidases provides insights into their likely roles in oxidative......The FAD prosthetic group of the ERV/ALR family of sulfhydryl oxidases is housed at the mouth of a 4-helix bundle and communicates with a pair of juxtaposed cysteine residues that form the proximal redox active disulfide. Most of these enzymes have one or more additional distal disulfide redox...

  20. Synthesis of dodecyl lauroyl benzene sulfonate and its application in enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Zhenggang; Wu, Le; Sun, Mingming; Jiang, Jian-zhong; Wang, Feng [Jiangnan Univ., Wuxi (China). School of Chemical and Material Engineering

    2011-09-15

    A new hydrophobic surfactant, dodecyl lauroyl benzene sulfonate (DLBS), was synthesized and its application in enhanced oil recovery by alkali-surfactant-polymer (ASP) flooding was studied. The results show that DLBS can be synthesized by reaction of industrial dodecyl benzene with lauroyl chloride in the presence of AlCl{sub 3}, followed by sulfonation with ClSO{sub 3}H and neutralization with NaOH. The lauroyl-group is confirmed to be connected to the para-position of the alkylbenzene by1HNMR spectrum. The synthesized DLBS is well soluble in pure water and reservoir (connate) water at 45 C. It is highly surface active which is indicated by its low CMC of 1.1 . 10{sup -5} mol/L, and its low surface tension, {gamma}{sub cmc} of 28.6 mN m{sup -1}. By mixing with heavy alkylbenzene sulfonates of relatively low average molar mass (387g mol{sup -1}) at a total surfactant concentration of 5 mM, DLBS can reduce the interfacial tension of Daqing crude oil/connate water to an order of 10{sup -3} mN/m at 45 C in the presence of 0.5-1.0 wt.% NaOH and 1000 mg L{sup -1} of polymer. If the NaOH was replaced by a gentle alkaline salt, Na{sub 2}CO{sub 3}, certain amounts of dodecyl dimethyl carboxy betaine were added and the concentration of Na{sub 2}CO{sub 3} was increased to 1.2-2.0 wt.%, the interfacial tension of Daqing crude oil/connate water can also be reduced to an ultralow value. Therefore DLBS is a good hydrophobic surfactant applicable in ASP flooding with either NaOH or Na{sub 2}CO{sub 3} as alkaline agents. (orig.)

  1. Tet1 Oxidase Regulates Neuronal Gene Transcription, Active DNA Hydroxy-methylation, Object Location Memory, and Threat Recognition Memory.

    Science.gov (United States)

    Kumar, Dinesh; Aggarwal, Milan; Kaas, Garrett A; Lewis, John; Wang, Jing; Ross, Daniel L; Zhong, Chun; Kennedy, Andrew; Song, Hongjun; Sweatt, J David

    2015-10-01

    A dynamic equilibrium between DNA methylation and demethylation of neuronal activity-regulated genes is crucial for memory processes. However, the mechanisms underlying this equilibrium remain elusive. Tet1 oxidase has been shown to play a key role in the active DNA demethylation in the CNS. In this study, we used Tet1 gene knockout (Tet1KO) mice to examine the involvement of Tet1 in memory consolidation and storage in the adult brain. We found that Tet1 ablation leads to: altered expression of numerous neuronal activity-regulated genes, compensatory upregulation of active demethylation pathway genes, and upregulation of various epigenetic modifiers. Moreover, Tet1KO mice showed an enhancement in the consolidation and storage of threat recognition (cued and contextual fear conditioning) and object location memories. We conclude that Tet1 plays a critical role in regulating neuronal transcription and in maintaining the epigenetic state of the brain associated with memory consolidation and storage.

  2. fMLP-Induced IL-8 Release Is Dependent on NADPH Oxidase in Human Neutrophils

    Directory of Open Access Journals (Sweden)

    María A. Hidalgo

    2015-01-01

    Full Text Available N-Formyl-methionyl-leucyl-phenylalanine (fMLP and platelet-activating factor (PAF induce similar intracellular signalling profiles; but only fMLP induces interleukin-8 (IL-8 release and nicotinamide adenine dinucleotide phosphate reduced (NADPH oxidase activity in neutrophils. Because the role of ROS on IL-8 release in neutrophils is until now controversial, we assessed if NADPH oxidase is involved in the IL-8 secretions and PI3K/Akt, MAPK, and NF-κB pathways activity induced by fMLP. Neutrophils were obtained from healthy volunteers. IL-8 was measured by ELISA, IL-8 mRNA by qPCR, and ROS production by luminol-amplified chemiluminescence, reduction of ferricytochrome c, and FACS. Intracellular pH changes were detected by spectrofluorescence. ERK1/2, p38 MAPK, and Akt phosphorylation were analysed by immunoblotting and NF-κB was analysed by immunocytochemistry. Hydroxy-3-methoxyaceto-phenone (HMAP, diphenyleneiodonium (DPI, and siRNA Nox2 reduced the ROS and IL-8 release in neutrophils treated with fMLP. HMAP, DPI, and amiloride (a Na+/H+ exchanger inhibitor inhibited the Akt phosphorylation and did not affect the p38 MAPK and ERK1/2 activity. DPI and HMAP reduced NF-κB translocation induced by fMLP. We showed that IL-8 release induced by fMLP is dependent on NADPH oxidase, and ROS could play a redundant role in cell signalling, ultimately activating the PI3K/Akt and NF-κB pathways in neutrophils.

  3. D-Amino acid oxidase bio-functionalized platforms: Toward an enhanced enzymatic bio-activity

    Science.gov (United States)

    Herrera, Elisa; Valdez Taubas, Javier; Giacomelli, Carla E.

    2015-11-01

    The purpose of this work is to study the adsorption process and surface bio-activity of His-tagged D-amino acid oxidase (DAAO) from Rhodotorula gracilis (His6-RgDAAO) as the first step for the development of an electrochemical bio-functionalized platform. With such a purpose this work comprises: (a) the His6-RgDAAO bio-activity in solution determined by amperometry, (b) the adsorption mechanism of His6-RgDAAO on bare gold and carboxylated modified substrates in the absence (substrate/COO-) and presence of Ni(II) (substrate/COO- + Ni(II)) determined by reflectometry, and (c) the bio-activity of the His6-RgDAAO bio-functionalized platforms determined by amperometry. Comparing the adsorption behavior and bio-activity of His6-RgDAAO on these different solid substrates allows understanding the contribution of the diverse interactions responsible for the platform performance. His6-RgDAAO enzymatic performance in solution is highly improved when compared to the previously used pig kidney (pk) DAAO. His6-RgDAAO exhibits an amperometrically detectable bio-activity at concentrations as low as those expected on a bio-functional platform; hence, it is a viable bio-recognition element of D-amino acids to be coupled to electrochemical platforms. Moreover, His6-RgDAAO bio-functionalized platforms exhibit a higher surface activity than pkDAAO physically adsorbed on gold. The platform built on Ni(II) modified substrates present enhanced bio-activity because the surface complexes histidine-Ni(II) provide with site-oriented, native-like enzymes. The adsorption mechanism responsible of the excellent performance of the bio-functionalized platform takes place in two steps involving electrostatic and bio-affinity interactions whose prevalence depends on the degree of surface coverage.

  4. 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....

  5. Enhanced Capacity of Polypyrrole/Anthraquinone Sulfonate/Graphene Composite as Cathode in Lithium Batteries

    International Nuclear Information System (INIS)

    Yang, Yang; He, Kuangchi; Yan, Peng; Wang, Dan; Wu, Xiaoyan; Zhao, Xin; Huang, Zilong; Zhang, Chunming; He, Dannong

    2014-01-01

    Highlights: • A polypyrrole (PPy)/anthraquinone sulfonate (AQS)/reduced graphene oxide (r-GO) composite was obtained via a facile electrochemical route. • A great enhancement in electrochemical performance was obtained for PPy/AQS/r-GO due to a remarkable combination of the redox property of AQS and the conductivity of r-GO. • The composite electrode delivered a specific discharge capacity of 127.2 mAh g −1 with a ca. 100% coulombic efficiency at 0.1 A g −1 . - Abstract: A facile electrochemical route was applied to prepare polypyrrole (PPy)/anthraquinone sulfonate (AQS)/reduced graphene oxide (r-GO) composite. The as-synthesized composite showed an interconnected porous structure, which is related to the competitive relationship between two dopants. The cyclic voltammograms and electrochemical impedance spectra confirmed that the presence of highly conductive r-GO in PPy matrix ensured an efficient redox reaction obtained for redox-active AQS. As a result, the PPy/AQS/r-GO composite exhibited an enhanced specific capacity of 127.2 mAh g −1 with ca. 100% coulombic efficiency at 0.1 A g −1 . Furthermore, the superior rate capability and cycling stability were also observed for PPy/AQS/r-GO, compared to AQS doped PPy. It is possible to adopt this co-dopants system for creating electro-active polymer materials with high capacities that are comparable to that of conventional inorganic intercalation electrode materials

  6. The radiation chemistry of aqueous solutions of sodium 9,10-anthraquinone-2-sulfonate

    International Nuclear Information System (INIS)

    Burchill, C.E.; Smith, D.M.; Charlton, J.L.

    1976-01-01

    The 60 Co γ-radiolysis of aqueous solutions of sodium 9,10-anthraquinone-2-sulfonate has been studied in acidic, unbuffered, and alkaline conditions and with addition of N 2 O and 2-propanol. Mechanisms are proposed to account for the yields of H 2 O 2 and hydroxylated anthraquinone sulfonates. In neutral solution, in the absence of O 2 , the OH and e - adducts undergo preferential cross termination. Reduction of the OH adduct leads to dehydration and regeneration of the quinone. (author)

  7. 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...

  8. Quantitative Collection and Enzymatic Activity of Glucose Oxidase Nanotubes Fabricated by Templated Layer-by-Layer Assembly.

    Science.gov (United States)

    Zhang, Shouwei; Demoustier-Champagne, Sophie; Jonas, Alain M

    2015-08-10

    We report on the fabrication of enzyme nanotubes in nanoporous polycarbonate membranes via the layer-by-layer (LbL) alternate assembly of polyethylenimine (PEI) and glucose oxidase (GOX), followed by dissolution of the sacrificial template in CH2Cl2, collection, and final dispersion in water. An adjuvant-assisted filtration methodology is exploited to extract quantitatively the nanotubes without loss of activity and morphology. Different water-soluble CH2Cl2-insoluble adjuvants are tested for maximal enzyme activity and nanotube stability; whereas NaCl disrupts the tubes by screening electrostatic interactions, the high osmotic pressure created by fructose also contributes to loosening the nanotubular structures. These issues are solved when using neutral, high molar mass dextran. The enzymatic activity of intact free nanotubes in water is then quantitatively compared to membrane-embedded nanotubes, showing that the liberated nanotubes have a higher catalytic activity in proportion to their larger exposed surface. Our study thus discloses a robust and general methodology for the fabrication and quantitative collection of enzymatic nanotubes and shows that LbL assembly provides access to efficient enzyme carriers for use as catalytic swarming agents.

  9. Cytochrome oxidase activity in the preoptic area correlates with differences in sexual behavior of intact and castrated male leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Sakata, J T; Crews, D

    2004-08-01

    Although the utility of analyzing behavioral experience effects on neural cytochrome oxidase (CO) activity is well recognized, the behavioral correlates of endogenous differences in CO activity have rarely been explored. In male leopard geckos (Eublepharis macularius), the incubation temperature experienced during embryogenesis (IncT) and age affect CO activity in the preoptic area (POA), an area that modulates copulatory behavior. In this study, the authors assessed whether differences in POA CO activity correlate with differences in sexual behavior in intact and castrated geckos. Males with IncT- and age-dependent increases in POA CO activity mounted females with shorter latencies while intact and after castration and ejaculated more frequently after castration. The authors discuss the predictive value of CO activity and propose similar parallels in other species.

  10. A Cell-Based Screen Reveals that the Albendazole Metabolite, Albendazole Sulfone, Targets Wolbachia

    Science.gov (United States)

    Bray, Walter M.; White, Pamela M.; Ruybal, Jordan; Lokey, R. Scott; Debec, Alain; Sullivan, William

    2012-01-01

    Wolbachia endosymbionts carried by filarial nematodes give rise to the neglected diseases African river blindness and lymphatic filariasis afflicting millions worldwide. Here we identify new Wolbachia-disrupting compounds by conducting high-throughput cell-based chemical screens using a Wolbachia-infected, fluorescently labeled Drosophila cell line. This screen yielded several Wolbachia-disrupting compounds including three that resembled Albendazole, a widely used anthelmintic drug that targets nematode microtubules. Follow-up studies demonstrate that a common Albendazole metabolite, Albendazole sulfone, reduces intracellular Wolbachia titer both in Drosophila melanogaster and Brugia malayi, the nematode responsible for lymphatic filariasis. Significantly, Albendazole sulfone does not disrupt Drosophila microtubule organization, suggesting that this compound reduces titer through direct targeting of Wolbachia. Accordingly, both DNA staining and FtsZ immunofluorescence demonstrates that Albendazole sulfone treatment induces Wolbachia elongation, a phenotype indicative of binary fission defects. This suggests that the efficacy of Albendazole in treating filarial nematode-based diseases is attributable to dual targeting of nematode microtubules and their Wolbachia endosymbionts. PMID:23028321

  11. Sulfonated copolyimide membranes derived from a novel diamine monomer with pendant benzimidazole groups for fuel cells

    DEFF Research Database (Denmark)

    Li, Wei; Guo, Xiaoxia; Aili, David

    2015-01-01

    . A series of sulfonated copolyimides (SPI) are prepared via random copolymerizatio of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) with a new diamine monomer with pendant benzimidazole groups, 2,2'-bis(4-(1H-benzo[d]imidazol-2-yl)phenoxy)benzidine (BIPOB), and a sulfonated diamine monomer 4,4'-bis...

  12. 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

  13. 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

  14. 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.

  15. Unique role of NADPH oxidase 5 in oxidative stress in human renal proximal tubule cells

    Directory of Open Access Journals (Sweden)

    Peiying Yu

    2014-01-01

    Full Text Available NADPH oxidases are the major sources of reactive oxygen species in cardiovascular, neural, and kidney cells. The NADPH oxidase 5 (NOX5 gene is present in humans but not rodents. Because Nox isoforms in renal proximal tubules (RPTs are involved in the pathogenesis of hypertension, we tested the hypothesis that NOX5 is differentially expressed in RPT cells from normotensive (NT and hypertensive subjects (HT. We found that NOX5 mRNA, total NOX5 protein, and apical membrane NOX5 protein were 4.2±0.7-fold, 5.2±0.7-fold, and 2.8±0.5-fold greater in HT than NT. Basal total NADPH oxidase activity was 4.5±0.2-fold and basal NOX5 activity in NOX5 immunoprecipitates was 6.2±0.2-fold greater in HT than NT (P=<0.001, n=6–14/group. Ionomycin increased total NOX and NOX5 activities in RPT cells from HT (P<0.01, n=4, ANOVA, effects that were abrogated by pre-treatment of the RPT cells with diphenylene-iodonium or superoxide dismutase. Silencing NOX5 using NOX5-siRNA decreased NADPH oxidase activity (−45.1±3.2% vs. mock-siRNA, n=6–8 in HT. D1-like receptor stimulation decreased NADPH oxidase activity to a greater extent in NT (−32.5±1.8% than HT (−14.8±1.8. In contrast to the marked increase in expression and activity of NOX5 in HT, NOX1 mRNA and protein were minimally increased in HT, relative to NT; total NOX2 and NOX4 proteins were not different between HT and NT, while the increase in apical RPT cell membrane NOX1, NOX2, and NOX4 proteins in HT, relative to NT, was much less than those observed with NOX5. Thus, we demonstrate, for the first time, that NOX5 is expressed in human RPT cells and to greater extent than the other Nox isoforms in HT than NT. We suggest that the increased expression of NOX5, which may be responsible for the increased oxidative stress in RPT cells in human essential hypertension, is caused, in part, by a defective renal dopaminergic system.

  16. Study of radiation grafted and sulfonated poly(tetrafluoroethylene-co-hexafluoropropylene), FEP, membranes

    International Nuclear Information System (INIS)

    Mohamed Mahmoud Nasef; Hamdani Saidi; Hussin Mohd Nor

    1999-01-01

    Radiation grafted and sulfonated FEP membranes were prepared by radiation-induced grafting of styrene onto poly(tetrafluoroethylene-co-hexafluoropropylene) films at room temperature and subsequently sulfonated. The membrane composition was controlled via variation of the grafting conditions such as type of diluent, irradiation dose, dose rate and monomer concentration. The membrane properties such as water uptake, ion exchange capacity and ionic conductivity were found to be strongly dependent upon the degree of grafting. The membranes were shown to have a good combination of physico-chemical properties, which made them promising for development of low cost proton exchange membranes

  17. Semi-fluorinated sulfonated polyimide membranes with enhanced proton selectivity and stability for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Li, Jinchao; Liu, Suqin; He, Zhen; Zhou, Zhi

    2016-01-01

    A series of semi-fluorinated sulfonated polyimides (6F-SPIs) are designed and synthesized via a one-step high-temperature polycondensation reaction. The sulfonation degrees of 6F-SPIs are controlled through changing the ratio of sulfonated diamine to non-sulfonated diamine in the casting solution. The physico-chemical properties and single cell performance of 6F-SPI membranes are thoroughly evaluated and compared to a non-fluorinated SPI membrane (6H-SPI-50) and a Nafion 115 membrane. The results show that the designed 6F-SPI membrane with a 50% sulfonation degree (6F-SPI-50) possesses the highest proton selectivity (1.613 × 10 5 S min cm −3 ) among all tested membranes. Besides, the 6F-SPI-50 membrane exhibits a promising performance for vanadium redox flow batteries (VRFBs), showing higher coulombic efficiencies (96.90–99.20%) and energy efficiencies (88.25–64.80%) than the Nafion 115 membrane (with coulombic efficiencies of 90.60–96.70% and energy efficiencies of 81.04–60.10%) at the current densities ranging from 20 to 100 mA cm −2 . Moreover, the 6F-SPI-50 membrane shows excellent chemical stability in the VRFB system. This work paves the way for the development of a new class of 6F-SPI membranes for the VRFB application.

  18. Stabilized Sulfonated Aromatic Polymers by in situ Solvothermal Cross-Linking

    Energy Technology Data Exchange (ETDEWEB)

    Di Vona, Maria Luisa, E-mail: divona@uniroma2.it; Sgreccia, Emanuela [Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Rome (Italy); Narducci, Riccardo; Pasquini, Luca [Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Rome (Italy); MAtériaux Divisés, Interfaces, Réactivité, ELectrochimie (MADIREL – UMR 7246), Aix Marseille Université, Marseille (France); Hou, Hongying [Faculty of Material and Engineering, Kunming University of Science and Technology, Kunming (China); Knauth, Philippe [MAtériaux Divisés, Interfaces, Réactivité, ELectrochimie (MADIREL – UMR 7246), Aix Marseille Université, Marseille (France)

    2014-10-10

    The cross-link reaction via sulfone bridges of sulfonated polyether ether ketone (SPEEK) by thermal treatment at 180°C in presence of dimethylsulfoxide is discussed. The modifications of properties subsequent to the cross-linking are presented. The mechanical strength as well as the hydrolytic stability increased with the thermal treatment time, i.e., with the degree of cross-linking. The proton conductivity was determined as function of temperature, IEC, degree of cross-linking, and hydration number. The memory effect, which is the membrane ability to “remember” the water uptake reached at high temperature also at lower temperature, is exploited in order to achieve high values of conductivity. Membranes swelled at 110°C can reach a conductivity of 0.14 S/cm at 80°C with a hydration number (λ) of 73.

  19. Three-dimensional activated graphene network-sulfonate-terminated polymer nanocomposite as a new electrode material for the sensitive determination of dopamine and heavy metal ions.

    Science.gov (United States)

    Yuan, Xiaoyan; Zhang, Yijia; Yang, Lu; Deng, Wenfang; Tan, Yueming; Ma, Ming; Xie, Qingji

    2015-03-07

    We report here that three-dimensional activated graphene networks (3DAGNs) are a better matrix to prepare graphene-polymer nanocomposites for sensitive electroanalysis than two-dimensional graphene nanosheets (2DGNs). 3DAGNs were synthesized in advance by the direct carbonization and simultaneous chemical activation of a cobalt ion-impregnated D113-type ion exchange resin, which showed an interconnected network structure and a large specific surface area. Then, the 3DAGN-sulfonate-terminated polymer (STP) nanocomposite was prepared via the in situ chemical co-polymerization of m-aminobenzene sulfonic acid and aniline in the presence of 3DAGNs. The 3DAGN-STP nanocomposite can adsorb dopamine (DA) and heavy metal ions, which was confirmed by quartz crystal microbalance studies. The 3DAGN-STP modified glassy carbon electrode (GCE) was used for the electrochemical detection of DA in the presence of ascorbic acid and uric acid, with a linear response range of 0.1-32 μM and a limit of detection of 10 nM. In addition, differential pulse voltammetry was used for the simultaneous determination of Cd(2+) and Pb(2+) at the 3DAGN-STP/GCE further modified with a bismuth film, exhibiting linear response ranges of 1-70 μg L(-1) for Cd(2+) and 1-80 μg L(-1) for Pb(2+) with limits of detection of 0.1 μg L(-1) for Cd(2+) and 0.2 μg L(-1) for Pb(2+). Because the 3DAGN-STP can integrate the advantages of 3DAGNs with STPs, the 3DAGN-STP/GCE was more sensitive than the bare GCE, 3DAGN/GCE, and 2DGN-STP/GCE for the determination of DA and heavy metal ions.

  20. Cloning and Functional Analysis of the Promoter of an Ascorbate Oxidase Gene from Gossypium hirsutum

    OpenAIRE

    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 exhibite...

  1. NADPH Oxidase Contributes to Photoreceptor Degeneration in Constitutively Active RAC1 Mice

    Science.gov (United States)

    Song, Hongman; Vijayasarathy, Camasamudram; Zeng, Yong; Marangoni, Dario; Bush, Ronald A.; Wu, Zhijian; Sieving, Paul A.

    2016-01-01

    Purpose The active form of small GTPase RAC1 is required for activation of NADPH oxidase (NOX), which in turn generates reactive oxygen species (ROS) in nonphagocytic cells. We explored whether NOX-induced oxidative stress contributes to rod degeneration in retinas expressing constitutively active (CA) RAC1. Methods Transgenic (Tg)–CA-RAC1 mice were given apocynin (10 mg/kg, intraperitoneal), a NOX inhibitor, or vehicle daily for up to 13 weeks. Superoxide production and oxidative damage were assessed by dihydroethidium staining and by protein carbonyls and malondialdehyde levels, respectively. Outer nuclear layer (ONL) cells were counted and electroretinogram (ERG) amplitudes measured in Tg-CA-RAC1 mice. Outer nuclear layer cells were counted in wild-type (WT) mice after transfer o