A novel endo-hydrogenase activity recycles hydrogen produced by nitrogen fixation.

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Gordon Ng

Full Text Available BACKGROUND: Nitrogen (N(2 fixation also yields hydrogen (H(2 at 1:1 stoichiometric amounts. In aerobic diazotrophic (able to grow on N(2 as sole N-source bacteria, orthodox respiratory hupSL-encoded hydrogenase activity, associated with the cell membrane but facing the periplasm (exo-hydrogenase, has nevertheless been presumed responsible for recycling such endogenous hydrogen. METHODS AND FINDINGS: As shown here, for Azorhizobium caulinodans diazotrophic cultures open to the atmosphere, exo-hydrogenase activity is of no consequence to hydrogen recycling. In a bioinformatic analysis, a novel seven-gene A. caulinodans hyq cluster encoding an integral-membrane, group-4, Ni,Fe-hydrogenase with homology to respiratory complex I (NADH: quinone dehydrogenase was identified. By analogy, Hyq hydrogenase is also integral to the cell membrane, but its active site faces the cytoplasm (endo-hydrogenase. An A. caulinodans in-frame hyq operon deletion mutant, constructed by "crossover PCR", showed markedly decreased growth rates in diazotrophic cultures; normal growth was restored with added ammonium--as expected of an H(2-recycling mutant phenotype. Using A. caulinodans hyq merodiploid strains expressing beta-glucuronidase as promoter-reporter, the hyq operon proved strongly and specifically induced in diazotrophic culture; as well, hyq operon induction required the NIFA transcriptional activator. Therefore, the hyq operon is constituent of the nif regulon. CONCLUSIONS: Representative of aerobic N(2-fixing and H(2-recycling alpha-proteobacteria, A. caulinodans possesses two respiratory Ni,Fe-hydrogenases: HupSL exo-hydrogenase activity drives exogenous H(2 respiration, and Hyq endo-hydrogenase activity recycles endogenous H(2, specifically that produced by N(2 fixation. To benefit human civilization, H(2 has generated considerable interest as potential renewable energy source as its makings are ubiquitous and its combustion yields no greenhouse gases. As

A novel endo-hydrogenase activity recycles hydrogen produced by nitrogen fixation.

Science.gov (United States)

Ng, Gordon; Tom, Curtis G S; Park, Angela S; Zenad, Lounis; Ludwig, Robert A

2009-01-01

Nitrogen (N(2)) fixation also yields hydrogen (H(2)) at 1:1 stoichiometric amounts. In aerobic diazotrophic (able to grow on N(2) as sole N-source) bacteria, orthodox respiratory hupSL-encoded hydrogenase activity, associated with the cell membrane but facing the periplasm (exo-hydrogenase), has nevertheless been presumed responsible for recycling such endogenous hydrogen. As shown here, for Azorhizobium caulinodans diazotrophic cultures open to the atmosphere, exo-hydrogenase activity is of no consequence to hydrogen recycling. In a bioinformatic analysis, a novel seven-gene A. caulinodans hyq cluster encoding an integral-membrane, group-4, Ni,Fe-hydrogenase with homology to respiratory complex I (NADH: quinone dehydrogenase) was identified. By analogy, Hyq hydrogenase is also integral to the cell membrane, but its active site faces the cytoplasm (endo-hydrogenase). An A. caulinodans in-frame hyq operon deletion mutant, constructed by "crossover PCR", showed markedly decreased growth rates in diazotrophic cultures; normal growth was restored with added ammonium--as expected of an H(2)-recycling mutant phenotype. Using A. caulinodans hyq merodiploid strains expressing beta-glucuronidase as promoter-reporter, the hyq operon proved strongly and specifically induced in diazotrophic culture; as well, hyq operon induction required the NIFA transcriptional activator. Therefore, the hyq operon is constituent of the nif regulon. Representative of aerobic N(2)-fixing and H(2)-recycling alpha-proteobacteria, A. caulinodans possesses two respiratory Ni,Fe-hydrogenases: HupSL exo-hydrogenase activity drives exogenous H(2) respiration, and Hyq endo-hydrogenase activity recycles endogenous H(2), specifically that produced by N(2) fixation. To benefit human civilization, H(2) has generated considerable interest as potential renewable energy source as its makings are ubiquitous and its combustion yields no greenhouse gases. As such, the reversible, group-4 Ni,Fe-hydrogenases, such

Inhibition of hydrogenase synthesis by DNA gyrase inhibitors in Bradyrhizobium japonicum

International Nuclear Information System (INIS)

Novak, P.D.; Maier, R.J.

1987-01-01

Derepression of an uptake hydrogenase in Bradyrhizobium japonicum is dependent on a microaerophilic environment. Addition of DNA gyrase inhibitors during derepression of hydrogenase specifically prevented expression of the hydrogenase enzyme. Antibodies to individual hydrogenase subunits failed to detect the protein after derepression in the presence of inhibitors, although there was no general inhibition of protein synthesis. The general pattern of proteins synthesized from 14 C-labeled amino acids during derepression was no significantly different whether proteins were labeled in the presence or in the absence of gyrase inhibitors. In contrast, if transcription or translation was inhibited by addition of inhibitors of those functions, virtually no proteins were labeled during derepression. This indicated that most of the 14 C-labeled proteins were synthesized de novo during derepression, synthesis of most proteins was unaffected by gyrase inhibitors, and the dependence of hydrogenase synthesis on gyrase activity was a specific one

Lactate dehydrogenase (LDH isoenzymes patterns in ocular tumours

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Singh Rajendra

1991-01-01

Full Text Available Estimation of lactate dehydrogenase (LDH isoenzymes in the serum and aqueous humor was carried out in 15 cases of benign ocular tumour, 15 cases of malignant tumor and 15 normal cases. Cases of both sexes aged between 1 year and 75 years were included. LDH, isoenzymes specially LDH4 and LDH5 are higher and LDH1 and LDH2 lower in sera of patients with malignant tumor specially retinoblastoma as compared to benign tumor cases and control cases. LDH isoenzymes in aqueous humor are significantly higher and show a characteristic pattern in retinoblastoma cases, the concentration was presumably too low in the control, malignant tumor other than retinoblastoma and benign tumor cases as its fractionation was not possible.

Production of biohydrogen by recombinant expression of [NiFe]-hydrogenase 1 in Escherichia coli

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Kim Jaoon YH

2010-07-01

Full Text Available Abstract Background Hydrogenases catalyze reversible reaction between hydrogen (H2 and proton. Inactivation of hydrogenase by exposure to oxygen is a critical limitation in biohydrogen production since strict anaerobic conditions are required. While [FeFe]-hydrogenases are irreversibly inactivated by oxygen, it was known that [NiFe]-hydrogenases are generally more tolerant to oxygen. The physiological function of [NiFe]-hydrogenase 1 is still ambiguous. We herein investigated the H2 production potential of [NiFe]-hydrogenase 1 of Escherichia coli in vivo and in vitro. The hyaA and hyaB genes corresponding to the small and large subunits of [NiFe]-hydrogenase 1 core enzyme, respectively, were expressed in BL21, an E. coli strain without H2 producing ability. Results Recombinant BL21 expressing [NiFe]-hydrogenase 1 actively produced H2 (12.5 mL H2/(h·L in 400 mL glucose minimal medium under micro-aerobic condition, whereas the wild type BL21 did not produce H2 even when formate was added as substrate for formate hydrogenlyase (FHL pathway. The majority of recombinant protein was produced as an insoluble form, with translocation of a small fraction to the membrane. However, the membrane fraction displayed high activity (~65% of total cell fraction, based on unit protein mass. Supplement of nickel and iron to media showed these metals contribute essentially to the function of [NiFe]-hydrogenase 1 as components of catalytic site. In addition, purified E. coli [NiFe]-hydrogenase 1 using his6-tag displayed oxygen-tolerant activity of ~12 nmol H2/(min·mg protein under a normal aeration environment, compared to [FeFe]-hydrogenase, which remains inactive under this condition. Conclusions This is the first report on physiological function of E. coli [NiFe]-hydrogenase 1 for H2 production. We found that [NiFe]-hydrogenase 1 has H2 production ability even under the existence of oxygen. This oxygen-tolerant property is a significant advantage because it is

Chemistry and the iron - only hydrogenase

International Nuclear Information System (INIS)

Tard, C.; Razavet, M.; Liu, X.; Ibrahim, S.; Pickett, Ch.

2005-01-01

Complete text of publication follows: Chemistry related to the hydrogenases is developing very rapidly and providing some informative insights into how the biological systems might function. Although still very much at a blue skies stage, there is some prospect for the design of artificial assemblies, materials and devices with technological application for hydrogen production/uptake provided robust system can be designed with low over potentials for hydrogen/proton interconversion (1). The iron-only hydrogenase possesses a peculiar di-iron unit coordinated by CO and CN, ligands which are normally associated with poisoning biological function. This sub-site unit is attached to a [4Fe4S] cubane center to form the catalytic site of the hydrogenase which is known as the 'H-cluster'. The synthesis of artificial sub-sites will first be described together with how their structures, spectroscopy and reactivity provides some key insights into the natural system viz. unprecedented bridging carbonyl and Fe(I) motifs in biology (2-4). How we have approached putting together the entire iron-sulfur framework of the H-cluster will then be described together with its electron-transfer and electrocatalytic properties (4). Finally, I will describe some early work on how we are beginning to incorporate structural motifs of the active-site into conducting polymer matrices, how they function as (albeit poor) electrocatalysts for hydrogen evolution, and where we see the way ahead. (1)The Chemistry and the Hydrogenases. D.J. Evans and C.J. Pickett, Chem. Soc. Rev., 32, 268-275, 2003; (2)Electron-Transfer at a Di-thiolate-Bridged Di-Iron Assembly; Electrocatalytic Hydrogen Evolution. S.J. Borg, T. Behrsing and S.P. Best, M. Ravazet, X. Liu and C.J. Pickett, J Amer. Chem. Soc., 2004, 126, 509-533; (3) Dissecting the intimate mechanism of cyanation of [Fe2S3] complexes related to the active site of all-iron hydrogenases by DFT analysis of energetics, transition states, intermediates and

Syngas fermentation to biofuels: Effects of hydrogen partial pressure on hydrogenase efficiency

International Nuclear Information System (INIS)

Skidmore, Bradley E.; Baker, Ryan A.; Banjade, Dila R.; Bray, Jason M.; Tree, Douglas R.; Lewis, Randy S.

2013-01-01

Producing biofuels from gasified biomass (synthesis gas) via microbial fermentation is currently being pursued as one alternative in biofuels development. In synthesis gas fermentation, reducing equivalents from H 2 oxidation via hydrogenase is important towards directing more carbon towards product formation. In this work, kinetic studies of H 2 utilization via the Clostridium P11 hydrogenase enzyme were performed to determine the most appropriate model to predict hydrogenase activity as a function of H 2 partial pressure. An important aspect of this work included the proper analysis of electron acceptors used in the kinetic studies. The K H 2 model parameter governing the effect of H 2 partial pressure on activity was ∼30 kPa (absolute), independent of the type and concentration of electron acceptor. The K H 2 value indicates that H 2 partial pressures typically associated with syngas fermentation will result in compromised efficiency of the hydrogenase activity. -- Highlights: ► We model hydrogenase activity as a function of H 2 and electron acceptors. ► Model shows the H 2 kinetic parameter is independent of electron acceptor. ► Hydrogenase efficiency is compromised at H 2 levels observed in gasified biomass

Turning cellulose waste into electricity: hydrogen conversion by a hydrogenase electrode.

Directory of Open Access Journals (Sweden)

Sergey M Abramov

Full Text Available Hydrogen-producing thermophilic cellulolytic microorganisms were isolated from cow faeces. Rates of cellulose hydrolysis and hydrogen formation were 0.2 mM L(-1 h(-1 and 1 mM L(-1 h(-1, respectively. An enzymatic fuel cell (EFC with a hydrogenase anode was used to oxidise hydrogen produced in a microbial bioreactor. The hydrogenase electrode was exposed for 38 days (912 h to a thermophilic fermentation medium. The hydrogenase activity remaining after continuous operation under load was 73% of the initial value.

Turning Cellulose Waste Into Electricity: Hydrogen Conversion by a Hydrogenase Electrode

Science.gov (United States)

Abramov, Sergey M.; Sadraddinova, Elmira R.; Shestakov, Andrey I.; Voronin, Oleg G.; Karyakin, Arkadiy A.; Zorin, Nikolay A.; Netrusov, Alexander I.

2013-01-01

Hydrogen-producing thermophilic cellulolytic microorganisms were isolated from cow faeces. Rates of cellulose hydrolysis and hydrogen formation were 0.2 mM L-1 h-1 and 1 mM L-1 h-1, respectively. An enzymatic fuel cell (EFC) with a hydrogenase anode was used to oxidise hydrogen produced in a microbial bioreactor. The hydrogenase electrode was exposed for 38 days (912 h) to a thermophilic fermentation medium. The hydrogenase activity remaining after continuous operation under load was 73% of the initial value. PMID:24312437

The interactions between three typical PPCPs and LDH

Science.gov (United States)

Li, Erwei; Liao, Libing; Lv, Guocheng; Li, Zhaohui; Yang, Chengxue; Lu, Yanan

2018-03-01

With a positively charged layered structure, layered double hydroxide has potential applications in remediation of anionic contaminants, which has been a hot topic for recent years. In this study, a Cl type Mg-Al hydrotalcite (Cl-LDH) was prepared by a co-precipitation method. The adsorption process of three pharmaceuticals and personal care products (PPCPs) (tetracycline (TC), diclofenac sodium (DF), chloramphenicol (CAP)) by Cl-LDH was investigated by X-ray diffraction (XRD), Zeta potential, dynamic light scattering (DLS), BET, FT-IR spectroscopy and molecular dynamics simulation. The results showed that the adsorption equilibrium of TC and DF could be reached in 120 min, and the maximum adsorption capacity of the Cl-LDH for TC and DF were 1.85 mmol/g and 0.95 mmol/g, respectively. The adsorption isothermal of TC was fitted with the Freundlich adsorption model, and the adsorption isothermal of DF was fitted with the Langmuir adsorption model. The adsorption dynamics of TC and DF followed the pseudo-second-order model. The adsorption mechanisms of the three PPCPs onto Cl-LDH were different based on the experimental results and molecular dynamics simulation. The TC adsorption on Cl-LDH was mainly driven by the electrostatic interactions between the negative charge of TC and the positive charge of Cl-LDH. The uptake of anionic DF was attributed both to ion exchange of DF for Cl- and the electrostatic interaction between the negatively charged DF and the positively charged structure layer of Cl-LDH. Cl-LDH does not adsorb the neutral CAP due to no electrostatic interaction. The molecular dynamic simulation further confirmed different configurations of the three selected PPCPs in the interlayer of Cl-LDH, which were responsible for the different uptake process of PPCPs on Cl-LDH.

A synthetic system links FeFe-hydrogenases to essential E. coli sulfur metabolism

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Grandl Gerald

2011-05-01

Full Text Available Abstract Background FeFe-hydrogenases are the most active class of H2-producing enzymes known in nature and may have important applications in clean H2 energy production. Many potential uses are currently complicated by a crucial weakness: the active sites of all known FeFe-hydrogenases are irreversibly inactivated by O2. Results We have developed a synthetic metabolic pathway in E. coli that links FeFe-hydrogenase activity to the production of the essential amino acid cysteine. Our design includes a complementary host strain whose endogenous redox pool is insulated from the synthetic metabolic pathway. Host viability on a selective medium requires hydrogenase expression, and moderate O2 levels eliminate growth. This pathway forms the basis for a genetic selection for O2 tolerance. Genetically selected hydrogenases did not show improved stability in O2 and in many cases had lost H2 production activity. The isolated mutations cluster significantly on charged surface residues, suggesting the evolution of binding surfaces that may accelerate hydrogenase electron transfer. Conclusions Rational design can optimize a fully heterologous three-component pathway to provide an essential metabolic flux while remaining insulated from the endogenous redox pool. We have developed a number of convenient in vivo assays to aid in the engineering of synthetic H2 metabolism. Our results also indicate a H2-independent redox activity in three different FeFe-hydrogenases, with implications for the future directed evolution of H2-activating catalysts.

Inducible hydrogenase in cyanobacteria enhances N/sub 2/ fixation. [Nostoc, anabaena

Energy Technology Data Exchange (ETDEWEB)

Tel-Or, E.; Luijk, L.W.; Packer, L.

1977-06-01

Whether hydrogenase is activated or induced, we found no evidence for activation of either consumption or production of H/sub 2/ in aerobically-grown cultures but both of these activities increased 5--20-fold when cultures are grown under H/sub 2/ gas. On the other hand, hydrogenase-catalyzed consumption of H/sub 2/ is stimulated by light and/or light plus CO/sub 2/ in hydrogenase-induced cultures. Nitrogenase activity appears to be induced in cultures grown under H/sub 2/. Studies unambiguously establish that in H/sub 2/-induced cultures hydrogenase manifests a cooperativity with nitrogenase. In the presence of H/sub 2/ the activity of nitrogenase is stimulated 3--5-fold such that rates of about 3 ..mu..mol N/sub 2/ fixed/mg chlorophyll/h are obtained if the method of Peterson and Burris is used to convert acetylene reduction data to equivalents of /sup 15/N/sub 2/ fixation to ammonia.

A hydrogenosomal [Fe]-hydrogenase from the anaerobic chytrid Neocallimastix sp L2

NARCIS (Netherlands)

Voncken, Frank G.J.; Boxma, Brigitte; Hoek, Angela H.A.M. van; Akhmanova, Anna S.; Vogels, Godfried D.; Huynen, Martijn; Veenhuis, Marten; Hackstein, Johannes H.P.

2002-01-01

The presence of a [Fe]-hydrogenase in the hydrogenosomes of the anaerobic chytridiomycete fungus Neocallimastix sp. L2 has been demonstrated by immunocytochemistry, subcellular fractionation, Western-blotting, and measurements of hydrogenase activity in the presence of various concentrations of

Purification and characterization of Desulfovibrio vulgaris (Hildenborough) hydrogenase expressed in Escherichia coli.

NARCIS (Netherlands)

Voordouw, G.; Hagen, W.R.; Kruse-Wolters, M.; Berkel-Arts, van A.; Veeger, C.

1987-01-01

Hydrogenase from Desulfovibrio vulgaris (Hildenborough) is a heterologous dimer of molecular mass 46 + 13.5 kDa. Its two structural genes have been cloned on a 4664-base-pair fragment of known sequence in the vector pUC9. Expression of hydrogenase polypeptides in Escherichia coli transformed with

Controlled release of ibuprofen using Mg Al LDH nano carrier

Science.gov (United States)

Dasgupta, Sudip

2017-08-01

In the present study, NSAID (non-steroidal anti-inflammatory drugs) such as ibuprofen in anionic form has been intercalated in-situ into the interlayer space of Mg Al LDH nanoparticle during co-precipitation of hydroxides. LDH nanohybrids are characterized by XRD, FTIR and UV spectroscopy. Mg1-xAlx(NO3)x(OH)2.nH2O nanoparticles were synthesized using co-precipitation method from an aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O. Ibuprofen was intercalated in inter layer space of Mg-Al LDH during coprecipitation of drug LDH conjugate in nitrogen atmosphere. The nanopowders synthesised were in the size range between 25 to 90 nm with an average particle size of 55 nm. XRD analysis proved that there is an increase in d003 spacing from 7.89 Å for pristine LDH to 14.71 Å for ibuprofen intercalated LDH due to the intercalation of bigger ibuprofen molecule in the interlayer space of LDH. FTIR analysis showed hydroxyl and carbonyl stretching of ibuprofen in LDH-IBU sample confirming the intercalation of ibuprofen in the interlayer structure of LDH. The drug release study in phosphate buffer solution at pH 7.4 using UV-Vis spectroscopy demonstrated that 50 % drug molecules were released in 15 hours and more than 85 % release was achieved after 36 hours.

Hydrogenase activity in aged, nonviable Desulfovibrio vulgaris cultures and its significance in anaerobic biocorrosion.

Science.gov (United States)

Chatelus, C; Carrier, P; Saignes, P; Libert, M F; Berlier, Y; Lespinat, P A; Fauque, G; Legall, J

1987-01-01

Batch cultures of Desulfovibrio vulgaris stored at 32 degrees C for 10 months have been found to retain 50% of the hydrogenase activity of a 1-day culture. The hydrogenase found in old cultures needs reducing conditions for its activation. Viable cell counts are negative after 6 months, showing that the hydrogenase activity does not depend on the presence of viable cells. These observations are of importance in the understanding of anaerobic biocorrosion of metals caused by depolarization phenomena. PMID:3310883

Filling Knowledge Gaps in Biological Networks: integrating global approaches to understand H2 metabolism in Chlamydomonas reinhardtii - Final Report

Energy Technology Data Exchange (ETDEWEB)

Posewitz, Matthew C

2011-06-30

The green alga Chlamydomonas reinhardtii (Chlamydomonas) has numerous genes encoding enzymes that function in fermentative pathways. Among these genes, are the [FeFe]-hydrogenases, pyruvate formate lyase, pyruvate ferredoxin oxidoreductase, acetate kinase, and phosphotransacetylase. We have systematically undertaken a series of targeted mutagenesis approaches to disrupt each of these key genes and omics techniques to characterize alterations in metabolic flux. Funds from DE-FG02-07ER64423 were specifically leveraged to generate mutants with disruptions in the genes encoding the [FeFe]-hydrogenases HYDA1 and HYDA2, pyruvate formate lyase (PFL1), and in bifunctional alcohol/aldehyde alcohol dehydrogenase (ADH1). Additionally funds were used to conduct global transcript profiling experiments of wildtype Chlamydomonas cells, as well as of the hydEF-1 mutant, which is unable to make H2 due to a lesion in the [FeFe]-hydrogenase biosynthetic pathway. In the wildtype cells, formate, acetate and ethanol are the dominant fermentation products with traces of CO2 and H2 also being produced. In the hydEF-1 mutant, succinate production is increased to offset the loss of protons as a terminal electron acceptor. In the pfl-1 mutant, lactate offsets the loss of formate production, and in the adh1-1 mutant glycerol is made instead of ethanol. To further probe the system, we generated a double mutant (pfl1-1 adh1) that is unable to synthesize both formate and ethanol. This strain, like the pfl1 mutants, secreted lactate, but also exhibited a significant increase in the levels of extracellular glycerol, acetate, and intracellular reduced sugars, and a decline in dark, fermentative H2 production. Whereas wild-type Chlamydomonas fermentation primarily produces formate and ethanol, the double mutant performs a complete rerouting of the glycolytic carbon to lactate and glycerol. Lastly, transcriptome data have been analysed for both the wildtype and hydEF-1, that correlate with our

Aquifex aeolicus membrane hydrogenase for hydrogen biooxidation: Role of lipids and physiological partners in enzyme stability and activity

Energy Technology Data Exchange (ETDEWEB)

Infossi, Pascale; Lojou, Elisabeth; Giudici-Orticoni, Marie-Therese [Unite de Bioenergetique et Ingenierie des Proteines, UPR 9036, Institut de Microbiologie de la Mediterranee - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20 (France); Chauvin, Jean-Paul [Institut de Biologie du developpement de Marseille Luminy, UMR 6216, Parc Scientifique de Luminy, 163 Avenue de Luminy, BP 907, 13009 Marseille (France); Herbette, Gaetan [Spectropole FI 1739, Aix-Marseille Universite case 511, Faculte de St Jerome Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20 (France); Brugna, Myriam [Unite de Bioenergetique et Ingenierie des Proteines, UPR 9036, Institut de Microbiologie de la Mediterranee - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20 (France); Universite de Provence, 3 Place Victor Hugo, 13331 Marseille Cedex 03 (France)

2010-10-15

Hydrogenase I from the hyperthermophilic bacterium Aquifex aeolicus is a good candidate for biotechnological devices thanks to its ability to oxidize hydrogen at high temperature, even in the presence of oxygen and CO. In order to enhance the enzyme stability and the catalytic efficiency, we investigated the hydrogen oxidation process with hydrogenase I embedded in a physiological-like environment. Hydrogenase I partners in the metabolic chain, namely membrane quinone and cytochrome b, were purified and fully characterized. The complex hydrogenase I-cytochrome b was inserted into liposomes. Surface Plasmon Resonance revealed that quinone took part in the stabilization of the complex. By use of molecular modelization and electrochemistry analysis, enzyme stability has been demonstrated to be stronger and enzymatic efficiency to be five times higher when hydrogenase is embedded into the liposomes. This result raises the possibility of using hydrogenases as biocatalysts in fuel cells. (author)

Improving cyanobacterail O₂-tolerance using CBS hydrogenase for hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Maness, Pin-Ching [National Renewable Energy Lab. (NREL), Golden, CO (United States); Eckert, Carrie [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wawrousek, Karen [National Renewable Energy Lab. (NREL), Golden, CO (United States); Noble, Scott [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pennington, Grant [National Renewable Energy Lab. (NREL), Golden, CO (United States); Yu, Jianping [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-11-11

Cyanobacterial H₂ production is a viable path to renewable H₂ with water serving as the electron donor and sunlight the energy source. A grand challenge is the sensitivity of the underlying hydrogenase to O₂, the latter an inherent byproduct of oxygenic photosynthesis. This challenge has been identified as a technical barrier in the Fuel Cell Technologies Office (FCTO) Multi-year Research, Development and Deployment Plan. One solution is to express in cyanobacterium an O₂-tolerant hydrogenase to circumvent this barrier. We have uncovered an O₂-tolerant hydrogenase from a photosynthetic bacterium Rubrivivax gelatinosus CBS (Casa Bonita Strain; hereafter “CBS”) with a half-life near 21 h when exposed to ambient O₂. We sequenced the CBS genome and identified two sets of maturation machineries hyp1 and hyp2. Transcripts expression analysis and mutagenesis revealed that hyp1 is responsible for the assembly of the O₂-tolerant CO-oxidation (Coo) hydrogenase and hyp2 is involved in the maturation of a H₂-uptake hydrogenase. The structural genes encoding the O₂-tolerant hydrogenase (cooLXUH) and maturation genes hyp1FABCDE were therefore cloned and expressed in the model cyanobacterium Synechocystis sp. PCC 6803. We obtained several recombinants displaying hydrogenase activity in a Synechocystis host lacking background activity, suggesting that the CBS hydrogenase is active in Synechocystis. Yet the activity is extremely low. To ensure balanced protein expression, we systematically optimized heterologous expression of 10 CBS genes by using stronger promoters and better ribosome binding site. Moreover we attempted the expression of cooM and cooK genes, verified to be important in CBS to afford activity. CooM is a very large protein and both CooM and CooK are membrane-associated. These properties limited our success in expressing both genes in Synechocystis, although they

Clinical significance of determination of changes of EPS IL-1β, IL-2, IL-10 and LDH5/LDH1 levels in patients with chronic prostatitis

International Nuclear Information System (INIS)

Chen Yongchang

2009-01-01

Objective: To investigate the clinical significance of the changes of expressed prostatic secretion IL-1β, IL-2, IL-10 and LDH5/LDH1 levels in patients with chronic prostatitis. Methods: Expressed prostatic secretion IL-1β, IL-2, IL-10 (with Radioimmunoassay) and LDH5/LDH1 (with cellulose acetate membrane electrophoresis) levels were determined in 32 patients with chronic prostatitis and 35 controls. These 32 patients were of 3 groups: 1)chronic bacterial prostatitis (CBP, n=10) 2) chronic pelvic pain syndrome IIIA (CPPS IIIA n=9) 3) CPPSIIIB n=13. Results: Expressed prostatic secretion levels of IL-1β, IL-2 and LDH5/LDH1 were significantly higher in patients with chronic bacterial prostatitis (CBP) groups than those in controls (all P 0.05). But the expressed prostatic secretion levels of IL-10 were still significantly lower in patients with chronic nonbacterial prostatitis, chronic pelvic pain syndrome(CPPSIIIB) groups than those in controls (all P<0.05). Conclusion: There were changes of expressed prostatic secretion IL-1β, IL-2, IL-10 and LDH5/LDH1 levels in patients with chronic prostatitis. Combined determination of the expressed prostatic secretion 4 markers levels is valuable for the diagnosis of chronic prostatitis and CPPSIII and for differentiation of CPPSIII types. (authors)

Purification and characterization of the hydrogen uptake hydrogenase from the hyperthermpholic archaebacterium Pyrodictium brockii

International Nuclear Information System (INIS)

Pihl, T.D.; Maier, R.J.

1991-01-01

Pyrodictium brockii is a hyperthermophilic archaebacterium with an optimal growth temperature of 105C. P. brokii is also a chemolithotroph, requiring H 2 and CO 2 for growth. The authors have purified the hydrogen uptake hydrogenase from membranes of P. brockii by reactive red affinity chromatography and sucrose gradient centrifugation. Colorometric analysis of Fe and S content in reactive red-purified hydrogenase revealed 8.7 ± 0.6 mol of Fe and 6.2 ± 1.2 mol of S per mol of hydrogenase. Growth of cells in 63 NiCl 2 resulted in label incorporation into reactive red-purified hydrogenase. Temperature stability studies indicated that the membrane-bound form of the enzyme was more stable than the solubilized purified form over a period of minutes with respect to temperature. However, the membranes were not able to protect the enzyme from thermal inactivation over a period of hours. The artificial electron acceptor specificity of the pure enzyme was similar to that of the membrane-bound form, but the purified enzyme was able to evolve H 2 in the presence of reduced methyl viologen. The K m of membrane-bound hydrogenase for H 2 was approximately 19 μM with methylene blue as the electron acceptor, whereas the purified enzyme had a higher K m value

Regulator LdhR and d-Lactate Dehydrogenase LdhA of Burkholderia multivorans Play Roles in Carbon Overflow and in Planktonic Cellular Aggregate Formation.

Science.gov (United States)

Silva, Inês N; Ramires, Marcelo J; Azevedo, Lisa A; Guerreiro, Ana R; Tavares, Andreia C; Becker, Jörg D; Moreira, Leonilde M

2017-10-01

LysR-type transcriptional regulators (LTTRs) are the most commonly found regulators in Burkholderia cepacia complex, comprising opportunistic pathogens causing chronic respiratory infections in cystic fibrosis (CF) patients. Despite LTTRs being global regulators of pathogenicity in several types of bacteria, few have been characterized in Burkholderia Here, we show that gene ldhR of B. multivorans encoding an LTTR is cotranscribed with ldhA encoding a d-lactate dehydrogenase and evaluate their implication in virulence traits such as exopolysaccharide (EPS) synthesis and biofilm formation. A comparison of the wild type (WT) and its isogenic Δ ldhR mutant grown in medium with 2% d-glucose revealed a negative impact on EPS biosynthesis and on cell viability in the presence of LdhR. The loss of viability in WT cells was caused by intracellular acidification as a consequence of the cumulative secretion of organic acids, including d-lactate, which was absent from the Δ ldhR mutant supernatant. Furthermore, LdhR is implicated in the formation of planktonic cellular aggregates. WT cell aggregates reached 1,000 μm in size after 24 h in liquid cultures, in contrast to Δ ldhR mutant aggregates that never grew more than 60 μm. The overexpression of d-lactate dehydrogenase LdhA in the Δ ldhR mutant partially restored the formed aggregate size, suggesting a role for fermentation inside aggregates. Similar results were obtained for surface-attached biofilms, with WT cells producing more biofilm. A systematic evaluation of planktonic aggregates in Burkholderia CF clinical isolates showed aggregates in 40 of 74. As CF patients' lung environments are microaerophilic and bacteria are found as free aggregates/biofilms, LdhR and LdhA might have central roles in adapting to this environment. IMPORTANCE Cystic fibrosis patients often suffer from chronic respiratory infections caused by several types of microorganisms. Among them are the Burkholderia cepacia complex bacteria, which

Exfoliation and dispersion of LDH modified with N ...

Indian Academy of Sciences (India)

N-tetrabromophthaloyl-glutamic in poly(vinyl alcohol): Morphological and thermal studies ... of cationic and non-ionic surfactants.20. Poly(vinyl alcohol) ... ultrasonic liquid processor, XL-2000 SERIES. Ultra- ... 2.5 Preparation of the PVA/M-LDH NC films. PVA/M-LDH .... ture, and light gray showed uniform ultrathin sheets that.

Replacing Electron Transport Cofactors with Hydrogenases

KAUST Repository

Laamarti, Rkia

2016-12-01

Enzymes have found applications in a broad range of industrial production processes. While high catalytic activity, selectivity and mild reaction conditions are attractive advantages of the biocatalysts, particularly costs arising from required cofactors pose a sever limitation. While cofactor-recycling systems are available, their use implies constraints for process set-up and conditions, which are a particular problem e.g. for solid-gas-phase reactions. Several oxidoreductases are able to directly exchange electrons with electrodes. Hence, the co-immobilization of both, an electron-utilizing and an electron-generating oxidoreductase on conductive nanoparticles should facilitate the direct electron flow from an enzymatic oxidation to a reduction reaction circumventing redox-cofactors requirements. In such a set-up, hydrogenases could generate and provide electrons directly form gaseous hydrogen. This thesis describes the co-immobilization of the oxygen tolerant hydrogenases from C. eutropha or C. metallidurans and cytochrome P450BM3 as test system. Conductive material in the form of carbon nanotubes (CNT) serves as a suitable support. A combination of the hydrogenase and the catalytic domain of P450BM3 immobilized on carbon nanotubes were tested for the oxidation of lauric acid in the presence of hydrogen instead of an electron-transport cofactor. The GC-MS analysis reveals the conversion of 4% of lauric acid (LA) into three products, which correspond to the hydroxylated lauric acid in three different positions with a total turnover (TON) of 34. The product distribution is similar to that obtained when using the wildtype P450BM3 with the nicotinamide adenine dinucleotide phosphate (NADPH) cofactor. Such electronic coupling couldn’t be achieved for the conversion of other substrates such as propane and cyclohexane, probably due to the high uncoupling rate within the heme-domain of cytochrome P450BM3 when unnatural substrates are introduced.

The effect of extracellular alkalinization on lactate metabolism of breast cancer stem cells: Overview of LDH-A, LDH-B, MCT1 and MCT4 gene expression

Science.gov (United States)

Neolaka, G. M. G.; Yustisia, I.; Sadikin, M.; Wanandi, S. I.

2017-08-01

Changes in the metabolic status of cancer cells are presumed to be correlated with the adjustment of these cells to extracellular changes. Cell glycolysis increases the production of intracellular lactate catalyzed by the lactate dehydrogenases, both LDH-A and LDH-B. An increase in intracellular lactate can affect extracellular pH balance through monocarboxylate transporters, particularly MCT1 and MCT4. This study aimed to analyze the effects of extracellular alkalinization on the lactate metabolism of human breast cancer stem cells (BCSCs). In this study, human primary BCSCs (CD24-/CD44+ cells) were treated with 100 mM sodium bicarbonate for 0.5, 24, and 48 h in DMEM F12/HEPES. After incubation, extracellular pH was measured and cells were harvested to extract the total RNA and protein. The expression of LDH-A, LDH-B, MCT1, and MCT4 mRNA genes were analyzed using qRT-PCR method. Our study shows that administration of sodium bicarbonate in the BCSC culture medium could increase extracellular pH. To balance the increase of extracellular pH, BCSCs regulated the expression of LDH-A, LDH-B, MCT1, and MCT4 genes. As the extracellular pH increases, the expression of LDH-A that converts pyruvate to lactate increased along with the increase of MCT 4 and MCT 1 expression, which act as lactate transporters. As the incubation time increases, the pH decreases, leading to the suppression of LDH-A and increase of LDH-B expression that converts lactate into pyruvate. Therefore, we suggest that the extracellular alkalinization by sodium bicarbonate in BCSCs affected the genes that regulate lactate metabolism.

Diversity and transcription of proteases involved in the maturation of hydrogenases in Nostoc punctiforme ATCC 29133 and Nostoc sp. strain PCC 7120

Science.gov (United States)

2009-01-01

Background The last step in the maturation process of the large subunit of [NiFe]-hydrogenases is a proteolytic cleavage of the C-terminal by a hydrogenase specific protease. Contrary to other accessory proteins these hydrogenase proteases are believed to be specific whereby one type of hydrogenases specific protease only cleaves one type of hydrogenase. In cyanobacteria this is achieved by the gene product of either hupW or hoxW, specific for the uptake or the bidirectional hydrogenase respectively. The filamentous cyanobacteria Nostoc punctiforme ATCC 29133 and Nostoc sp strain PCC 7120 may contain a single uptake hydrogenase or both an uptake and a bidirectional hydrogenase respectively. Results In order to examine these proteases in cyanobacteria, transcriptional analyses were performed of hupW in Nostoc punctiforme ATCC 29133 and hupW and hoxW in Nostoc sp. strain PCC 7120. These studies revealed numerous transcriptional start points together with putative binding sites for NtcA (hupW) and LexA (hoxW). In order to investigate the diversity and specificity among hydrogeanse specific proteases we constructed a phylogenetic tree which revealed several subgroups that showed a striking resemblance to the subgroups previously described for [NiFe]-hydrogenases. Additionally the proteases specificity was also addressed by amino acid sequence analysis and protein-protein docking experiments with 3D-models derived from bioinformatic studies. These studies revealed a so called "HOXBOX"; an amino acid sequence specific for protease of Hox-type which might be involved in docking with the large subunit of the hydrogenase. Conclusion Our findings suggest that the hydrogenase specific proteases are under similar regulatory control as the hydrogenases they cleave. The result from the phylogenetic study also indicates that the hydrogenase and the protease have co-evolved since ancient time and suggests that at least one major horizontal gene transfer has occurred. This co

Diversity and transcription of proteases involved in the maturation of hydrogenases in Nostoc punctiforme ATCC 29133 and Nostoc sp. strain PCC 7120

Directory of Open Access Journals (Sweden)

Lindblad Peter

2009-03-01

Full Text Available Abstract Background The last step in the maturation process of the large subunit of [NiFe]-hydrogenases is a proteolytic cleavage of the C-terminal by a hydrogenase specific protease. Contrary to other accessory proteins these hydrogenase proteases are believed to be specific whereby one type of hydrogenases specific protease only cleaves one type of hydrogenase. In cyanobacteria this is achieved by the gene product of either hupW or hoxW, specific for the uptake or the bidirectional hydrogenase respectively. The filamentous cyanobacteria Nostoc punctiforme ATCC 29133 and Nostoc sp strain PCC 7120 may contain a single uptake hydrogenase or both an uptake and a bidirectional hydrogenase respectively. Results In order to examine these proteases in cyanobacteria, transcriptional analyses were performed of hupW in Nostoc punctiforme ATCC 29133 and hupW and hoxW in Nostoc sp. strain PCC 7120. These studies revealed numerous transcriptional start points together with putative binding sites for NtcA (hupW and LexA (hoxW. In order to investigate the diversity and specificity among hydrogeanse specific proteases we constructed a phylogenetic tree which revealed several subgroups that showed a striking resemblance to the subgroups previously described for [NiFe]-hydrogenases. Additionally the proteases specificity was also addressed by amino acid sequence analysis and protein-protein docking experiments with 3D-models derived from bioinformatic studies. These studies revealed a so called "HOXBOX"; an amino acid sequence specific for protease of Hox-type which might be involved in docking with the large subunit of the hydrogenase. Conclusion Our findings suggest that the hydrogenase specific proteases are under similar regulatory control as the hydrogenases they cleave. The result from the phylogenetic study also indicates that the hydrogenase and the protease have co-evolved since ancient time and suggests that at least one major horizontal gene transfer

A hydrogen-producing, hydrogenase-free mutant strain of Nostoc punctiforme ATCC 29133

Energy Technology Data Exchange (ETDEWEB)

Lindberg, P.; Lindblad, P. [Uppsala Univ. (Sweden). Dept. of Physiological Botany; Schuetz, K.; Happe, T. [Universitaet Bonn (Germany). Botanisches Inst.

2002-12-01

The hupL gene, encoding the uptake hydrogenase large subunit, in Nostoc sp. strain ATCC 29133, a strain lacking a bidirectional hydrogenase, was inactivated by insertional mutagenesis. Recombinant strains were isolated and analysed, and one hupL{sup -} strain, NHM5, was selected for further study. Cultures of NHM5 were grown under nitrogen-fixing conditions and H{sub 2} evolution under air was observed using an H{sub 2} electrode. (Author)

Structural and gene expression analyses of uptake hydrogenases ...

Indian Academy of Sciences (India)

2013-10-01

Oct 1, 2013 ... subunits resemble the structures of known [NiFe] hydrogenases (Volbeda et al. 1995) ..... abundant lipid in Frankia cells and in nitrogen-fixing nodule tissue. .... Vignais PM and Billoud B 2007 Occurrence, classification, and.

Preparation and enhanced properties of polyaniline/grafted intercalated ZnAl-LDH nanocomposites

Science.gov (United States)

Hu, Jinlong; Gan, Mengyu; Ma, Li; Zhang, Jun; Xie, Shuang; Xu, Fenfang; Shen, JiYue Zheng Xiaoyu; Yin, Hui

2015-02-01

The polymeric nanocomposites (PANI/AD-LDH) were prepared by in situ polymerization based on polyaniline (PANI) and decavanadate-intercalated and γ-aminopropyltriethoxysilane (APTS)-grafted ZnAl-layered double hydroxide (AD-LDH). FTIR and XRD studies confirm the grafting of APTS with decavanadate-intercalated LDH (D-LDH). The extent of grafting (wt%) has also been estimated on the basis of the residue left in nitrogen atmosphere at 800 °C in TGA. SEM and XPS studies show the partial exfoliation of grafted LDH in the PANI matrix and the interfacial interaction between PANI and grafted LDH, respectively. The grafted intercalated layered double hydroxide in reinforcing the properties of the PANI nanocomposites has also been investigated by open circuit potential (OCP), tafel polarization curves (TAF), electrochemical impendence spectroscopy (EIS), salt spray test and TGA-DTA. The experimental results indicate that the PANI/AD-LDH has a higher thermal stability and anticorrosion properties relative to the PANI.

One-Pot Microwave-Assisted Synthesis of Graphene/Layered Double Hydroxide (LDH) Nanohybrids

Institute of Scientific and Technical Information of China (English)

Sunil P Lonkar; Jean-Marie Raquez; Philippe Dubois

2015-01-01

A facile and rapid method to synthesize graphene/layered double hydroxide (LDH) nanohybrids by a micro-wave technique is demonstrated. The synthesis procedure involves hydrothermal crystallization of Zn–Al LDH at the same time in situ reduction of graphene oxide (GO) to graphene. The microstructure, composition, and morphology of the resulting graphene/LDH nanohybrids were characterized. The results confirmed the formation of nanohybrids and the reduction of graphene oxide. The growth mechanism of LDH and in situ reduction of GO were discussed. The LDH sheet growth was found to prevent the scrolling of graphene layers in resulting hybrids. The electrochemical properties exhibit superior performance for graphene/Zn–Al LDH hybrids over pristine graphene. The present approach may open a strategy in hybridizing graphene with multimetallic nano-oxides and hydroxides using microwave method.

One-Pot Microwave-Assisted Synthesis of Graphene/Layered Double Hydroxide(LDH) Nanohybrids

Institute of Scientific and Technical Information of China (English)

Sunil P.Lonkar; Jean-Marie Raquez; Philippe Dubois

2015-01-01

A facile and rapid method to synthesize graphene/layered double hydroxide(LDH)nanohybrids by a microwave technique is demonstrated.The synthesis procedure involves hydrothermal crystallization of Zn–Al LDH at the same time in situ reduction of graphene oxide(GO)to graphene.The microstructure,composition,and morphology of the resulting graphene/LDH nanohybrids were characterized.The results confirmed the formation of nanohybrids and the reduction of graphene oxide.The growth mechanism of LDH and in situ reduction of GO were discussed.The LDH sheet growth was found to prevent the scrolling of graphene layers in resulting hybrids.The electrochemical properties exhibit superior performance for graphene/Zn–Al LDH hybrids over pristine graphene.The present approach may open a strategy in hybridizing graphene with multimetallic nano-oxides and hydroxides using microwave method.

Epilepsy treatment. Targeting LDH enzymes with a stiripentol analog to treat epilepsy.

Science.gov (United States)

Sada, Nagisa; Lee, Suni; Katsu, Takashi; Otsuki, Takemi; Inoue, Tsuyoshi

2015-03-20

Neuronal excitation is regulated by energy metabolism, and drug-resistant epilepsy can be suppressed by special diets. Here, we report that seizures and epileptiform activity are reduced by inhibition of the metabolic pathway via lactate dehydrogenase (LDH), a component of the astrocyte-neuron lactate shuttle. Inhibition of the enzyme LDH hyperpolarized neurons, which was reversed by the downstream metabolite pyruvate. LDH inhibition also suppressed seizures in vivo in a mouse model of epilepsy. We further found that stiripentol, a clinically used antiepileptic drug, is an LDH inhibitor. By modifying its chemical structure, we identified a previously unknown LDH inhibitor, which potently suppressed seizures in vivo. We conclude that LDH inhibitors are a promising new group of antiepileptic drugs. Copyright © 2015, American Association for the Advancement of Science.

Improved hydrogen production by uptake hydrogenase deficient mutant strain of Rhodobacter sphaeroides O.U.001

Energy Technology Data Exchange (ETDEWEB)

Kars, Goekhan; Guenduez, Ufuk; Yuecel, Meral [Department of Biological Sciences, Middle East Technical University, 06531 Ankara (Turkey); Rakhely, Gabor; Kovacs, Kornel L. [Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged (Hungary); Eroglu, Inci [Department of Chemical Engineering, Middle East Technical University, 06531 Ankara (Turkey)

2008-06-15

Rhodobacter sphaeroides O.U.001 is a purple non-sulfur bacterium producing hydrogen under photoheterotrophic conditions. Hydrogen is produced by Mo-nitrogenase enzyme and substantial amount of H{sub 2} is reoxidized by a membrane-bound uptake hydrogenase in the wild type strain. To improve the hydrogen producing capacity of the cells, a suicide vector containing a gentamicin cassette in the hupSL genes was introduced into R. sphaeroiodes O.U.001 and the uptake hydrogenase genes were destroyed by site directed mutagenesis. The correct integration of the construct was confirmed by uptake hydrogenase activity measurement, PCR and subsequent sequence analysis. The wild type and the mutant cells showed similar growth patterns but the total volume of hydrogen gas evolved by the mutant was 20% higher than that of the wild type strain. This result demonstrated that the hydrogen produced by the nitrogenase was not consumed by uptake hydrogenase leading to higher hydrogen production. (author)

Novel [NiFe]- and [FeFe]-hydrogenase gene transcripts indicative of active facultative aerobes and obligate anaerobes in earthworm gut contents.

Science.gov (United States)

Schmidt, Oliver; Wüst, Pia K; Hellmuth, Susanne; Borst, Katharina; Horn, Marcus A; Drake, Harold L

2011-09-01

The concomitant occurrence of molecular hydrogen (H(2)) and organic acids along the alimentary canal of the earthworm is indicative of ongoing fermentation during gut passage. Fermentative H(2) production is catalyzed by [FeFe]-hydrogenases and group 4 [NiFe]-hydrogenases in obligate anaerobes (e.g., Clostridiales) and facultative aerobes (e.g., Enterobacteriaceae), respectively, functional groups that might respond differently to contrasting redox conditions. Thus, the objectives of this study were to assess the redox potentials of the alimentary canal of Lumbricus terrestris and analyze the hydrogenase transcript diversities of H(2) producers in glucose-supplemented gut content microcosms. Although redox potentials in the core of the alimentary canal were variable on an individual worm basis, average redox potentials were similar. The lowest redox potentials occurred in the foregut and midgut regions, averaging 40 and 110 mV, respectively. Correlation plots between hydrogenase amino acid sequences and 16S rRNA gene sequences indicated that closely related hydrogenases belonged to closely related taxa, whereas distantly related hydrogenases did not necessarily belong to distantly related taxa. Of 178 [FeFe]-hydrogenase gene transcripts, 177 clustered in 12 Clostridiales-affiliated operational taxonomic units, the majority of which were indicative of heretofore unknown hydrogenases. Of 86 group 4 [NiFe]-hydrogenase gene transcripts, 79% and 21% were affiliated with organisms in the Enterobacteriaceae and Aeromonadaceae, respectively. The collective results (i) suggest that fermenters must cope with variable and moderately oxidative redox conditions along the alimentary canal, (ii) demonstrate that heretofore undetected hydrogenases are present in the earthworm gut, and (iii) corroborate previous findings implicating Clostridiaceae and Enterobacteriaceae as active fermentative taxa in earthworm gut content.

Model synthetic complexes of the hydrogenase with different protonation sites; Complexes synthetiques modeles de l'hydrogenase avec differents sites de protonation

Energy Technology Data Exchange (ETDEWEB)

Capon, J.F.; Gloaguen, F.; Morvan, D.; Schollhammer, Ph.; Talarmin, J.; Yaouanc, J.J. [Universite de Bretagne Occidentale, UMR CNRS 6521, Chimie, Electrochimie Moleculaires et Chimie Analytique, Faculte des Sciences, 29 - Brest (France)

2005-07-01

The data obtained until now seem to indicate that the hydrogen production by hydrogenases induces a proton-hydride coupling. In taking the structures of theses enzymes active sites (determined by X-ray diffraction) as a basis, it can be thought that this proton-hydride coupling is facilitated by the juxtaposition of two protonation sites, the metallic center M and the basic group of an E ligand of the coordination sphere. Contrarily to the supposed running of the hydrogenases enzymes, the homogeneous catalysts of the protons reduction, described in the literature, present a reactivity which is either on an alone metallic site or on a metal-metal bond. This work deals then with the preparation of complexes having two juxtaposed protonation sites. Some iron dinuclear compounds have been synthesized and their properties studied. (O.M.)

Designed Surface Residue Substitutions in [NiFe] Hydrogenase that Improve Electron Transfer Characteristics

Directory of Open Access Journals (Sweden)

Isaac T. Yonemoto

2015-01-01

Full Text Available Photobiological hydrogen production is an attractive, carbon-neutral means to convert solar energy to hydrogen. We build on previous research improving the Alteromonas macleodii “Deep Ecotype” [NiFe] hydrogenase, and report progress towards creating an artificial electron transfer pathway to supply the hydrogenase with electrons necessary for hydrogen production. Ferredoxin is the first soluble electron transfer mediator to receive high-energy electrons from photosystem I, and bears an electron with sufficient potential to efficiently reduce protons. Thus, we engineered a hydrogenase-ferredoxin fusion that also contained several other modifications. In addition to the C-terminal ferredoxin fusion, we truncated the C-terminus of the hydrogenase small subunit, identified as the available terminus closer to the electron transfer region. We also neutralized an anionic patch surrounding the interface Fe-S cluster to improve transfer kinetics with the negatively charged ferredoxin. Initial screening showed the enzyme tolerated both truncation and charge neutralization on the small subunit ferredoxin-binding face. While the enzyme activity was relatively unchanged using the substrate methyl viologen, we observed a marked improvement from both the ferredoxin fusion and surface modification using only dithionite as an electron donor. Combining ferredoxin fusion and surface charge modification showed progressively improved activity in an in vitro assay with purified enzyme.

Hydrogenase-3 contributes to anaerobic acid resistance of Escherichia coli.

Science.gov (United States)

Noguchi, Ken; Riggins, Daniel P; Eldahan, Khalid C; Kitko, Ryan D; Slonczewski, Joan L

2010-04-12

Hydrogen production by fermenting bacteria such as Escherichia coli offers a potential source of hydrogen biofuel. Because H(2) production involves consumption of 2H(+), hydrogenase expression is likely to involve pH response and regulation. Hydrogenase consumption of protons in E. coli has been implicated in acid resistance, the ability to survive exposure to acid levels (pH 2-2.5) that are three pH units lower than the pH limit of growth (pH 5-6). Enhanced survival in acid enables a larger infective inoculum to pass through the stomach and colonize the intestine. Most acid resistance mechanisms have been defined using aerobic cultures, but the use of anaerobic cultures will reveal novel acid resistance mechanisms. We analyzed the pH regulation of bacterial hydrogenases in live cultures of E. coli K-12 W3110. During anaerobic growth in the range of pH 5 to 6.5, E. coli expresses three hydrogenase isoenzymes that reversibly oxidize H(2) to 2H(+). Anoxic conditions were used to determine which of the hydrogenase complexes contribute to acid resistance, measured as the survival of cultures grown at pH 5.5 without aeration and exposed for 2 hours at pH 2 or at pH 2.5. Survival of all strains in extreme acid was significantly lower in low oxygen than for aerated cultures. Deletion of hyc (Hyd-3) decreased anoxic acid survival 3-fold at pH 2.5, and 20-fold at pH 2, but had no effect on acid survival with aeration. Deletion of hyb (Hyd-2) did not significantly affect acid survival. The pH-dependence of H(2) production and consumption was tested using a H(2)-specific Clark-type electrode. Hyd-3-dependent H(2) production was increased 70-fold from pH 6.5 to 5.5, whereas Hyd-2-dependent H(2) consumption was maximal at alkaline pH. H(2) production, was unaffected by a shift in external or internal pH. H(2) production was associated with hycE expression levels as a function of external pH. Anaerobic growing cultures of E. coli generate H(2) via Hyd-3 at low external pH, and

Cyanobacterial Hydrogenases and Hydrogen Metabolism Revisited: Recent Progress and Future Prospects

Directory of Open Access Journals (Sweden)

Namita Khanna

2015-05-01

Full Text Available Cyanobacteria have garnered interest as potential cell factories for hydrogen production. In conjunction with photosynthesis, these organisms can utilize inexpensive inorganic substrates and solar energy for simultaneous biosynthesis and hydrogen evolution. However, the hydrogen yield associated with these organisms remains far too low to compete with the existing chemical processes. Our limited understanding of the cellular hydrogen production pathway is a primary setback in the potential scale-up of this process. In this regard, the present review discusses the recent insight around ferredoxin/flavodoxin as the likely electron donor to the bidirectional Hox hydrogenase instead of the generally accepted NAD(PH. This may have far reaching implications in powering solar driven hydrogen production. However, it is evident that a successful hydrogen-producing candidate would likely integrate enzymatic traits from different species. Engineering the [NiFe] hydrogenases for optimal catalytic efficiency or expression of a high turnover [FeFe] hydrogenase in these photo-autotrophs may facilitate the development of strains to reach target levels of biohydrogen production in cyanobacteria. The fundamental advancements achieved in these fields are also summarized in this review.

How oxygen attacks [FeFe] hydrogenases from photosynthetic organisms

Science.gov (United States)

Stripp, Sven T.; Goldet, Gabrielle; Brandmayr, Caterina; Sanganas, Oliver; Vincent, Kylie A.; Haumann, Michael; Armstrong, Fraser A.; Happe, Thomas

2009-01-01

Green algae such as Chlamydomonas reinhardtii synthesize an [FeFe] hydrogenase that is highly active in hydrogen evolution. However, the extreme sensitivity of [FeFe] hydrogenases to oxygen presents a major challenge for exploiting these organisms to achieve sustainable photosynthetic hydrogen production. In this study, the mechanism of oxygen inactivation of the [FeFe] hydrogenase CrHydA1 from C. reinhardtii has been investigated. X-ray absorption spectroscopy shows that reaction with oxygen results in destruction of the [4Fe-4S] domain of the active site H-cluster while leaving the di-iron domain (2FeH) essentially intact. By protein film electrochemistry we were able to determine the order of events leading up to this destruction. Carbon monoxide, a competitive inhibitor of CrHydA1 which binds to an Fe atom of the 2FeH domain and is otherwise not known to attack FeS clusters in proteins, reacts nearly two orders of magnitude faster than oxygen and protects the enzyme against oxygen damage. These results therefore show that destruction of the [4Fe-4S] cluster is initiated by binding and reduction of oxygen at the di-iron domain—a key step that is blocked by carbon monoxide. The relatively slow attack by oxygen compared to carbon monoxide suggests that a very high level of discrimination can be achieved by subtle factors such as electronic effects (specific orbital overlap requirements) and steric constraints at the active site. PMID:19805068

Dissecting the hydrogenase expression and activity of transformed escherichia coli with the bidirectional NiFe-hydrogenase from synechocystis sp. PCC 6803

International Nuclear Information System (INIS)

Moon, Yu Ran; Lee, Min Hee; An, Byung Chull; Chung, Byung Yeoup; Kim, Jae Sung; Kim, Jin Hong; Park, Youn Il; Kim, Cha Soon

2009-01-01

Synechocystis bidirectional hydrogenase genes (hoxEFUYH) and their putative promoter regions and transformed into E. coli. The hox genes were transcribed in the E. coli cells carrying the vector construct of pCCIFOS::phox::hox or pCCIFOS::pT7::hox and translated into HoxEFUYH proteins, suggesting that the putative hox promoter can be constitutively activated in E. coli. Accordingly, the total hydrogenase activity was markedly increased up to 192% or 169% in the transformed cells, while the hydrogen uptake was decreased up to about 30% of the negative control. Although the gene expression of LexA, the only one transcription regulator proven for the hox genes, was substantially decreased in the pCCIFOS::phox::hox cells after γ-irradiation of 30 Gy, the expression levels of HoxEFUYH proteins were not altered significantly. Thus, it is also suggested that other transcription regulators as well as LexA might contribute to activation of the hox promoter in E. coli

Accumulating the hydride state in the catalytic cycle of [FeFe]-hydrogenases

Science.gov (United States)

Winkler, Martin; Senger, Moritz; Duan, Jifu; Esselborn, Julian; Wittkamp, Florian; Hofmann, Eckhard; Apfel, Ulf-Peter; Stripp, Sven Timo; Happe, Thomas

2017-07-01

H2 turnover at the [FeFe]-hydrogenase cofactor (H-cluster) is assumed to follow a reversible heterolytic mechanism, first yielding a proton and a hydrido-species which again is double-oxidized to release another proton. Three of the four presumed catalytic intermediates (Hox, Hred/Hred and Hsred) were characterized, using various spectroscopic techniques. However, in catalytically active enzyme, the state containing the hydrido-species, which is eponymous for the proposed heterolytic mechanism, has yet only been speculated about. We use different strategies to trap and spectroscopically characterize this transient hydride state (Hhyd) for three wild-type [FeFe]-hydrogenases. Applying a novel set-up for real-time attenuated total-reflection Fourier-transform infrared spectroscopy, we monitor compositional changes in the state-specific infrared signatures of [FeFe]-hydrogenases, varying buffer pH and gas composition. We selectively enrich the equilibrium concentration of Hhyd, applying Le Chatelier's principle by simultaneously increasing substrate and product concentrations (H2/H+). Site-directed manipulation, targeting either the proton-transfer pathway or the adt ligand, significantly enhances Hhyd accumulation independent of pH.

[Investigations on the distribution of serum LDH isoenzymes of patients with carcinoma laryngis (author's transl)].

Science.gov (United States)

T-Tomity, I; Takács, O

1979-12-01

The distribution of lactate dehydrogenase (LDH) isoenzymes in healthy blood donors and in patients suffering histological identified tumor (neoplasms) laryngis was investigated. The values of 110 healthy persons (controls) proved to be comparable with the average data described in literature. The LDH distribution pattern of 90 tumour affected persons showed significant differences comparing with controls. The alteration appears as absolute increase in LDH-1 (H4) isoenzyme parallel with progressive decrease in the hybrid enzyme rations containing M subunits (LDH-2, LDH-3, LDH-4), and the LDH-5 consisting of four M sununits was undetectable. The conclusions drawn from our investigations seem to be in agreement with Warburg's conception, supposing that in malignant tumours the aerob glycolysis increases. The determination of LDH isoenzyme distributions for diagnostic purposes in clinical practice is recommended.

[Fe]-hydrogenases in green algae: photo-fermentation and hydrogen evolution under sulfur deprivation

Energy Technology Data Exchange (ETDEWEB)

Winkler, M.; Hemschemeier, A.; Happe, T. [Botanisches Institut der Universitat Bonn (Germany); Gotor, C. [CSIC y Universidad de Sevilla (Spain). Instituto de Bioquimica Vegetal y Fotosintesis; Melis, A. [University of California, Berkeley, CA (United States). Department of Plant and Microbial Biology

2002-12-01

Recent studies indicate that [Fe]-hydrogenases and H{sub 2} metabolism are widely distributed among green algae. The enzymes are simple structured and catalyze H{sub 2} evolution with similar rates than the more complex [Fe]-hydrogenases from bacteria. Different green algal species developed diverse strategies to survive under sulfur deprivation. Chlamydomonas reinhardtii evolves large quantities of hydrogen gas in the absence of sulfur. In a sealed culture of C. reinhardtii, the photosynthetic O{sub 2} evolution rate drops below the rate of respiratory O{sub 2} consumption due to a reversible inhibition of photosystem II, thus leading to an intracellular anaerobiosis. The algal cells survive under these anaerobic conditions by switching their metabolism to a kind of photo-fermentation. Although possessing a functional [Fe]-hydrogenase gene, the cells of Scenedesmus obliquus produce no significant amounts of H{sub 2} under S-depleted conditions. Biochemical analyses indicate that S. obliquus decreases almost the complete metabolic activities while maintaining a low level of respiratory activity. (author)

Second coordination sphere effects in [FeFe]-Hydrogenase mimics

NARCIS (Netherlands)

Zaffaroni, R.

2017-01-01

Iron–iron hydrogenase are fascinating metallo‐enzymes able to reversibly perform interconversion between protons and dihydrogen with high rates at low overpotentials. Nevertheless, activity and stability of synthetic analogues without the protein matrix are rarely comparable to the enzyme. This

The Synthesis and Characterization of Gold-Core/LDH-Shell Nanoparticles

Science.gov (United States)

Rearick, Colton

In recent years, the field of nanomedicine has progressed at an astonishing rate, particularly with respect to applications in cancer treatment and molecular imaging. Although organic systems have been the frontrunners, inorganic systems have also begun to show promise, especially those based upon silica and magnetic nanoparticles (NPs). Many of these systems are being designed for simultaneous therapeutic and diagnostic capabilities, thus coining the term, theranostics. A unique class of inorganic systems that shows great promise as theranostics is that of layered double hydroxides (LDH). By synthesis of a core/shell structures, e.g. a gold nanoparticle (NP) core and LDH shell, the multifunctional theranostic may be developed without a drastic increase in the structural complexity. To demonstrate initial proof-of-concept of a potential (inorganic) theranostic platform, a Au-core/LDH-shell nanovector has been synthesized and characterized. The LDH shell was heterogeneously nucleated and grown on the surface of silica coated gold NPs via a coprecipitation method. Polyethylene glycol (PEG) was introduced in the initial synthesis steps to improve crystallinity and colloidal stability. Additionally, during synthesis, fluorescein isothiocyanate (FITC) was intercalated into the interlayer spacing of the LDH. In contrast to the PEG stabilization, a post synthesis citric acid treatment was used as a method to control the size and short-term stability. The heterogeneous core-shell system was characterized with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), dynamic light scattering (DLS), and powder x-ray diffraction (PXRD). A preliminary in vitro study carried out with the assistance of Dr. Kaushal Rege's group at Arizona State University was to demonstrate the endocytosis capability of homogeneously-grown LDH NPs. The DLS measurements of the core-shell NPs indicated an average particle size of 212nm. The PXRD analysis showed that PEG

Connection between the membrane electron transport system and Hyn hydrogenase in the purple sulfur bacterium, Thiocapsa roseopersicina BBS.

Science.gov (United States)

Tengölics, Roland; Mészáros, Lívia; Győri, E; Doffkay, Zsolt; Kovács, Kornél L; Rákhely, Gábor

2014-10-01

Thiocapsa. roseopersicina BBS has four active [NiFe] hydrogenases, providing an excellent opportunity to examine their metabolic linkages to the cellular redox processes. Hyn is a periplasmic membrane-associated hydrogenase harboring two additional electron transfer subunits: Isp1 is a transmembrane protein, while Isp2 is located on the cytoplasmic side of the membrane. In this work, the connection of HynSL to various electron transport pathways is studied. During photoautotrophic growth, electrons, generated from the oxidation of thiosulfate and sulfur, are donated to the photosynthetic electron transport chain via cytochromes. Electrons formed from thiosulfate and sulfur oxidation might also be also used for Hyn-dependent hydrogen evolution which was shown to be light and proton motive force driven. Hyn-linked hydrogen uptake can be promoted by both sulfur and nitrate. The electron flow from/to HynSL requires the presence of Isp2 in both directions. Hydrogenase-linked sulfur reduction could be inhibited by a QB site competitive inhibitor, terbutryne, suggesting a redox coupling between the Hyn hydrogenase and the photosynthetic electron transport chain. Based on these findings, redox linkages of Hyn hydrogenase are modeled. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrogen Production by a Hyperthermophilic Membrane-Bound Hydrogenase in Soluble Nanolipoprotein Particles

Energy Technology Data Exchange (ETDEWEB)

Baker, S E; Hopkins, R C; Blanchette, C; Walsworth, V; Sumbad, R; Fischer, N; Kuhn, E; Coleman, M; Chromy, B; Letant, S; Hoeprich, P; Adams, M W; Henderson, P T

2008-10-22

Hydrogenases constitute a promising class of enzymes for ex vivo hydrogen production. Implementation of such applications is currently hindered by oxygen sensitivity and, in the case of membrane-bound hydrogenases (MBH), poor water solubility. Nanolipoprotein particles (NLPs), formed from apolipoproteins and phospholipids, offer a novel means to incorporate MBH into in a well-defined water-soluble matrix that maintains the enzymatic activity and is amenable to incorporation into more complex architectures. We report the synthesis, hydrogen-evolving activity and physical characterization of the first MBH-NLP assembly. This may ultimately lead to the development of biomimetic hydrogen production devices.

Hydrogenase-3 contributes to anaerobic acid resistance of Escherichia coli.

Directory of Open Access Journals (Sweden)

Ken Noguchi

Full Text Available BACKGROUND: Hydrogen production by fermenting bacteria such as Escherichia coli offers a potential source of hydrogen biofuel. Because H(2 production involves consumption of 2H(+, hydrogenase expression is likely to involve pH response and regulation. Hydrogenase consumption of protons in E. coli has been implicated in acid resistance, the ability to survive exposure to acid levels (pH 2-2.5 that are three pH units lower than the pH limit of growth (pH 5-6. Enhanced survival in acid enables a larger infective inoculum to pass through the stomach and colonize the intestine. Most acid resistance mechanisms have been defined using aerobic cultures, but the use of anaerobic cultures will reveal novel acid resistance mechanisms. METHODS AND PRINCIPAL FINDINGS: We analyzed the pH regulation of bacterial hydrogenases in live cultures of E. coli K-12 W3110. During anaerobic growth in the range of pH 5 to 6.5, E. coli expresses three hydrogenase isoenzymes that reversibly oxidize H(2 to 2H(+. Anoxic conditions were used to determine which of the hydrogenase complexes contribute to acid resistance, measured as the survival of cultures grown at pH 5.5 without aeration and exposed for 2 hours at pH 2 or at pH 2.5. Survival of all strains in extreme acid was significantly lower in low oxygen than for aerated cultures. Deletion of hyc (Hyd-3 decreased anoxic acid survival 3-fold at pH 2.5, and 20-fold at pH 2, but had no effect on acid survival with aeration. Deletion of hyb (Hyd-2 did not significantly affect acid survival. The pH-dependence of H(2 production and consumption was tested using a H(2-specific Clark-type electrode. Hyd-3-dependent H(2 production was increased 70-fold from pH 6.5 to 5.5, whereas Hyd-2-dependent H(2 consumption was maximal at alkaline pH. H(2 production, was unaffected by a shift in external or internal pH. H(2 production was associated with hycE expression levels as a function of external pH. CONCLUSIONS: Anaerobic growing

Degradability Enhancement of Poly(Lactic Acid) by Stearate-Zn3Al LDH Nanolayers

Science.gov (United States)

Eili, Mahboobeh; Shameli, Kamyar; Ibrahim, Nor Azowa; Yunus, Wan Md Zin Wan

2012-01-01

Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid)/layered double hydroxide (PLA/LDH) nanocomposites from PLA and stearate-Zn3Al LDH. A solution casting method was used to prepare PLA/stearate-Zn3Al LDH nanocomposites. The anionic clay Zn3Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn3Al LDH nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn3Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn3Al LDH nanocomposites showed that the presence of around 1.0–3.0 wt % of the stearate-Zn3Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn3Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA. PMID:22942682

Identifying Malignant Pleural Effusion by A Cancer Ratio (Serum LDH: Pleural Fluid ADA Ratio).

Science.gov (United States)

Verma, Akash; Abisheganaden, John; Light, R W

2016-02-01

We studied the diagnostic potential of serum lactate dehydrogenase (LDH) in malignant pleural effusion. Retrospective analysis of patients hospitalized with exudative pleural effusion in 2013. Serum LDH and serum LDH: pleural fluid ADA ratio was significantly higher in cancer patients presenting with exudative pleural effusion. In multivariate logistic regression analysis, pleural fluid ADA was negatively correlated 0.62 (0.45-0.85, p = 0.003) with malignancy, whereas serum LDH 1.02 (1.0-1.03, p = 0.004) and serum LDH: pleural fluid ADA ratio 0.94 (0.99-1.0, p = 0.04) was correlated positively with malignant pleural effusion. For serum LDH: pleural fluid ADA ratio, a cut-off level of >20 showed sensitivity, specificity of 0.98 (95 % CI 0.92-0.99) and 0.94 (95 % CI 0.83-0.98), respectively. The positive likelihood ratio was 32.6 (95 % CI 10.7-99.6), while the negative likelihood ratio at this cut-off was 0.03 (95 % CI 0.01-0.15). Higher serum LDH and serum LDH: pleural fluid ADA ratio in patients presenting with exudative pleural effusion can distinguish between malignant and non-malignant effusion on the first day of hospitalization. The cut-off level for serum LDH: pleural fluid ADA ratio of >20 is highly predictive of malignancy in patients with exudative pleural effusion (whether lymphocytic or neutrophilic) with high sensitivity and specificity.

Self-assembling organomodified Co/Al based layered double hydroxides (LDH) via one-step route

Institute of Scientific and Technical Information of China (English)

WANG De-yi; A.LEUTERITZ; U.WAGENKNECHT; G.HEINRICH

2009-01-01

The preparation of self-assembling organomodified Co/Al-layered double hydroxide (LDH) via one-step route was studied.A common surfactant,sodium dodecylbenzenesulfonate (DBS),was employed as an organic modifier.The behavior and structure of self-assembled intercalated organic Co/Al-LDH were investigated by FTIR,SEM,WAXS,element analysis and TGA.Based upon the WAXS results and calculation by Bragg equation,the interlayer distance (d value) for organic Co/Al-LDH is enlarged from 0.75 nm to 3.10 nm,showing that the self-assembling behavior has been carried out successfully.Considering the observation from SEM,the product shows the morphology of organic Co/Al-LDH of a layered structure.In addition,FTIR,element analysis and TGA analysis show that the modifier is intercalated into the gallery of the Co/Al-LDH.Since organic modification for nanofiller is deemed to be necessary before applying it into polymer,the successful preparation of organomodified Co/Al-LDH will be significantly beneficial to the preparation and investigation of novel polymer/LDH nanocomposite.

HupW Protease Specifically Required for Processing of the Catalytic Subunit of the Uptake Hydrogenase in the Cyanobacterium Nostoc sp. Strain PCC 7120

Science.gov (United States)

Lindberg, Pia; Devine, Ellenor; Stensjö, Karin

2012-01-01

The maturation process of [NiFe] hydrogenases includes a proteolytic cleavage of the large subunit. We constructed a mutant of Nostoc strain PCC 7120 in which hupW, encoding a putative hydrogenase-specific protease, is inactivated. Our results indicate that the protein product of hupW selectively cleaves the uptake hydrogenase in this cyanobacterium. PMID:22020512

Molecular biology of microbial hydrogenases.

Science.gov (United States)

Vignais, P M; Colbeau, A

2004-07-01

Hydrogenases (H2ases) are metalloproteins. The great majority of them contain iron-sulfur clusters and two metal atoms at their active center, either a Ni and an Fe atom, the [NiFe]-H2ases, or two Fe atoms, the [FeFe]-H2ases. Enzymes of these two classes catalyze the reversible oxidation of hydrogen gas (H2 2 H+ + 2 e-) and play a central role in microbial energy metabolism; in addition to their role in fermentation and H2 respiration, H2ases may interact with membrane-bound electron transport systems in order to maintain redox poise, particularly in some photosynthetic microorganisms such as cyanobacteria. Recent work has revealed that some H2ases, by acting as H2-sensors, participate in the regulation of gene expression and that H2-evolving H2ases, thought to be involved in purely fermentative processes, play a role in membrane-linked energy conservation through the generation of a protonmotive force. The Hmd hydrogenases of some methanogenic archaea constitute a third class of H2ases, characterized by the absence of Fe-S cluster and the presence of an iron-containing cofactor with catalytic properties different from those of [NiFe]- and [FeFe]-H2ases. In this review, we emphasise recent advances that have greatly increased our knowledge of microbial H2ases, their diversity, the structure of their active site, how the metallocenters are synthesized and assembled, how they function, how the synthesis of these enzymes is controlled by external signals, and their potential use in biological H2 production.

Preparation of melt-spun antimicrobially modified LDH/polyolefin nanocomposite fibers.

Science.gov (United States)

Kutlu, Burak; Schröttner, Percy; Leuteritz, Andreas; Boldt, Regine; Jacobs, Enno; Heinrich, Gert

2014-08-01

Layered double hydroxide (LDH) was synthesized and organically modified with camphorsulfonic acid (CSA) and ciprofloxacin. The thermal stability of CSA was improved remarkably under LDH shielding. A minimal inhibitory concentration of free CSA against tested bacteria was determined in order to define the essential quantity in LDH modification. The modified LDHs were melt-compounded with high density polyethylene and the prepared nanocomposites were further melt-spun using a piston-type spinning device. The melt-spun fibers were tested for their antimicrobial activity against Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Enterobacter cloacae, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. CSA integrated fibers show susceptibility against Gram-positive bacteria and ciprofloxacin integrated fibers showed activity against both Gram-positive and Gram-negative bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Proteolytic cleavage orchestrates cofactor insertion and protein assembly in [NiFe]-hydrogenase biosynthesis.

Science.gov (United States)

Senger, Moritz; Stripp, Sven T; Soboh, Basem

2017-07-14

Metalloenzymes catalyze complex and essential processes, such as photosynthesis, respiration, and nitrogen fixation. For example, bacteria and archaea use [NiFe]-hydrogenases to catalyze the uptake and release of molecular hydrogen (H 2 ). [NiFe]-hydrogenases are redox enzymes composed of a large subunit that harbors a NiFe(CN) 2 CO metallo-center and a small subunit with three iron-sulfur clusters. The large subunit is synthesized with a C-terminal extension, cleaved off by a specific endopeptidase during maturation. The exact role of the C-terminal extension has remained elusive; however, cleavage takes place exclusively after assembly of the [NiFe]-cofactor and before large and small subunits form the catalytically active heterodimer. To unravel the functional role of the C-terminal extension, we used an enzymatic in vitro maturation assay that allows synthesizing functional [NiFe]-hydrogenase-2 of Escherichia coli from purified components. The maturation process included formation and insertion of the NiFe(CN) 2 CO cofactor into the large subunit, endoproteolytic cleavage of the C-terminal extension, and dimerization with the small subunit. Biochemical and spectroscopic analysis indicated that the C-terminal extension of the large subunit is essential for recognition by the maturation machinery. Only upon completion of cofactor insertion was removal of the C-terminal extension observed. Our results indicate that endoproteolytic cleavage is a central checkpoint in the maturation process. Here, cleavage temporally orchestrates cofactor insertion and protein assembly and ensures that only cofactor-containing protein can continue along the assembly line toward functional [NiFe]-hydrogenase. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Ab Initio Electronic Structure Calculation of [4Fe-3S] Cluster of Hydrogenase as Dihydrogen Dissociation/Production Catalyst

Science.gov (United States)

Kim, Jaehyun; Kang, Jiyoung; Nishigami, Hiroshi; Kino, Hiori; Tateno, Masaru

2018-03-01

Hydrogenases catalyze both the dissociation and production of dihydrogen (H2). Most hydrogenases are inactivated rapidly and reactivated slowly (in vitro), in the presence of dioxygen (O2) and H2, respectively. However, membrane-bound [NiFe] hydrogenases (MBHs) sustain their activity even together with O2, which is termed "O2 tolerance". In previous experimental analyses, an MBH was shown to include a hydroxyl ion (OH-) bound to an Fe of the super-oxidized [4Fe-3S]5+ cluster in the proximity of the [NiFe] catalytic cluster. In this study, the functional role of the OH- in the O2 tolerance was investigated by ab initio electronic structure calculation of the [4Fe-3S] proximal cluster. The analysis revealed that the OH- significantly altered the electronic structure, thereby inducing the delocalization of the lowest unoccupied molecular orbital (LUMO) toward the [NiFe] catalytic cluster, which may intermediate the electron transfer between the catalytic and proximal clusters. This can promote the O2-tolerant catalytic cycle in the hydrogenase reaction.

RNAi knock-down of LHCBM1, 2 and 3 increases photosynthetic H2 production efficiency of the green alga Chlamydomonas reinhardtii.

Directory of Open Access Journals (Sweden)

Melanie Oey

Full Text Available Single cell green algae (microalgae are rapidly emerging as a platform for the production of sustainable fuels. Solar-driven H2 production from H2O theoretically provides the highest-efficiency route to fuel production in microalgae. This is because the H2-producing hydrogenase (HYDA is directly coupled to the photosynthetic electron transport chain, thereby eliminating downstream energetic losses associated with the synthesis of carbohydrate and oils (feedstocks for methane, ethanol and oil-based fuels. Here we report the simultaneous knock-down of three light-harvesting complex proteins (LHCMB1, 2 and 3 in the high H2-producing Chlamydomonas reinhardtii mutant Stm6Glc4 using an RNAi triple knock-down strategy. The resultant Stm6Glc4L01 mutant exhibited a light green phenotype, reduced expression of LHCBM1 (20.6% ±0.27%, LHCBM2 (81.2% ±0.037% and LHCBM3 (41.4% ±0.05% compared to 100% control levels, and improved light to H2 (180% and biomass (165% conversion efficiencies. The improved H2 production efficiency was achieved at increased solar flux densities (450 instead of ∼100 µE m(-2 s(-1 and high cell densities which are best suited for microalgae production as light is ideally the limiting factor. Our data suggests that the overall improved photon-to-H2 conversion efficiency is due to: 1 reduced loss of absorbed energy by non-photochemical quenching (fluorescence and heat losses near the photobioreactor surface; 2 improved light distribution in the reactor; 3 reduced photoinhibition; 4 early onset of HYDA expression and 5 reduction of O2-induced inhibition of HYDA. The Stm6Glc4L01 phenotype therefore provides important insights for the development of high-efficiency photobiological H2 production systems.

Cyanobacterial hydrogenases and biohydrogen: present status and future potential

International Nuclear Information System (INIS)

Lindblad, P.; Tamagnini, P.

2000-01-01

Molecular hydrogen (H 2 ) is an environmentally clean energy-carrier that may be a valuable alternative to the limited fossil fuel resources of today. For photobiological H 2 production, photosynthetic cyanobacteria are among the ideal candidates since they have the simplest nutritional requirements: they can grow in air (N 2 and CO 2 ), water (electrons and reductant), and mineral salts with light (solar energy) as the only source of energy. In N 2 -fixing cyanobacteria, H 2 is mainly produced by nitrogenases, but its partial consumption is quickly catalyzed by a unidirectional uptake hydrogenase. In addition, a bidirectional (reversible) enzyme may also oxidize some of the molecular hydrogen. The same enzyme will, under certain conditions, evolve H 2 Filamentous cyanobacteria have been used in bioreactors for the photobiological conversion of water to hydrogen. However, the conversion efficiencies achieved are low because the net H 2 production is the result of H 2 evolution via a nitrogenase and H 2 consumption mainly via an uptake hydrogenase. Consequently, the improvements of the conversion efficiencies are achieved e.g. through the optimization of the conditions for H 2 evolution by nitrogenase, through the production of mutants deficient in H 2 uptake activity and by an increased H 2 -evolution by a bidirectional enzyme. Symbiotic cells are of fundamental interest since they in situ 'function as a bioreactor', High metabolism, transfer of metabolite(s) from symbiont to host but almost no growth. In the present communication we will present the general knowledge about hydrogen metabolism/hydrogenases in filamentous cyanobacteria focusing on recent advances using molecular techniques, outline strategies for improving the capacity of H 2 -production by filamentous strains, and stress the importance of international cooperations and networks. (author)

[NiFe] hydrogenase structural and functional models: new bio-inspired catalysts for hydrogen evolution

International Nuclear Information System (INIS)

Oudart, Y.

2006-09-01

Hydrogenase enzymes reversibly catalyze the oxidation and production of hydrogen in a range close to the thermodynamic potential. The [NiFe] hydrogenase active site contains an iron-cyano-carbonyl moiety linked to a nickel atom which is in an all sulphur environment. Both the active site originality and the potential development of an hydrogen economy make the synthesis of functional and structural models worthy. To take up this challenge, we have synthesised mononuclear ruthenium models and more importantly, nickel-ruthenium complexes, mimicking some structural features of the [NiFe] hydrogenase active site. Ruthenium is indeed isoelectronic to iron and some of its complexes are well-known to bear hydrides. The compounds described in this study have been well characterised and their activity in proton reduction has been successfully tested. Most of them are able to catalyze this reaction though their electrocatalytic potentials remain much more negative compared to which of platinum. The studied parameters point out the importance of the complexes electron richness, especially of the nickel environment. Furthermore, the proton reduction activity is stable for several hours at good rates. The ruthenium environment seems important for this stability. Altogether, these compounds represent the very first catalytically active [NiFe] hydrogenase models. Important additional results of this study are the synergetic behaviour of the two metals in protons reduction and the evidence of a protonation step as the limiting step of the catalytic cycle. We have also shown that a basic site close to ruthenium improves the electrocatalytic potential of the complexes. (author)

LDH ACTIVITY IN COPPER INTOXICATION OF CARASSIUS AURATUS GIBELIO GILLS AND INTESTINE

Directory of Open Access Journals (Sweden)

DANIELA TEODORESCU

2008-05-01

Full Text Available The pathological effects of two sublethal concentrations (100 μg/l and 250 μg/l of copper (CuSO4x5H2O on goldfish Carassius auratus gibelio were studied for 7,14 and 21 days. The specific activity of LDH in gills and intestine, two target organs that uptake the metal from the water were assayed. In gills at 100 μg Cu2+/l the specific activity of LDH was gradually decreasing, while in the intestine, after 7 days of exposure, the enzymatic activity was distinct significantly increased. LDH activity demonstrated a hypoxic condition and a stimulation of glycolysis. In the both organs ,the 250 μg Cu2+/l concentration generated a decrease of LDH specific activity after 7 days followed by an increase of this after 14 and 21 days of exposure. Histologically, the modifications are, generally, directly correlated with the toxicant dose and exposure time.

LDH nanocages synthesized with MOF templates and their high performance as supercapacitors

Science.gov (United States)

Jiang, Zhen; Li, Zhengping; Qin, Zhenhua; Sun, Haiyan; Jiao, Xiuling; Chen, Dairong

2013-11-01

Layered double hydroxides (LDHs) are currently attracting intense research interest for their various applications. Three LDH hollow nano-polyhedra are synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as the templates. The nanocages well inherit the rhombic dodecahedral shape of the ZIF-67 templates, and the shell is composed of nanosheets assembled with an edge-to-face stacking. This is the first synthesis of the LDH non-spherical structures. And the mechanism of utilizing metal-organic framework (MOF) nanocrystals as templates is explored. Control of the simultaneous reactions, the precipitation of the shells and the template etching, is extremely crucial to the preparation of the perfect nanocages. And the Ni-Co LDH nanocages exhibit superior pseudocapacitance property due to their novel hierarchical and submicroscopic structures.Layered double hydroxides (LDHs) are currently attracting intense research interest for their various applications. Three LDH hollow nano-polyhedra are synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as the templates. The nanocages well inherit the rhombic dodecahedral shape of the ZIF-67 templates, and the shell is composed of nanosheets assembled with an edge-to-face stacking. This is the first synthesis of the LDH non-spherical structures. And the mechanism of utilizing metal-organic framework (MOF) nanocrystals as templates is explored. Control of the simultaneous reactions, the precipitation of the shells and the template etching, is extremely crucial to the preparation of the perfect nanocages. And the Ni-Co LDH nanocages exhibit superior pseudocapacitance property due to their novel hierarchical and submicroscopic structures. Electronic supplementary information (ESI) available: Experimental details, XRD, TEM, SEM, and XPS images. See DOI: 10.1039/c3nr03829g

Biomimetic peptide-based models of [FeFe]-hydrogenases: utilization of phosphine-containing peptides

Energy Technology Data Exchange (ETDEWEB)

Roy, Souvik [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Nguyen, Thuy-Ai D. [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Gan, Lu [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Jones, Anne K. [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA

2015-01-01

Peptide based models for [FeFe]-hydrogenase were synthesized utilizing unnatural phosphine-amino acids and their electrocatalytic properties were investigated in mixed aqueous-organic solvents.

Dynamic water vapor sorption on Mg(Ga3+)O mixed oxides: Analysis of the LDH thermal regeneration process

International Nuclear Information System (INIS)

Bedolla-Valdez, Zaira I.; Ramirez-Solis, Sergio; Prince, Julia; Lima, Enrique; Pfeiffer, Heriberto; Valente, Jaime S.

2013-01-01

Highlights: ► Ga-LDH regeneration process was analyzed varying the relative humidity. ► Ga-LDH rehydrates faster than aluminum content LDH materials. ► Gallium seems to favor diffusion processeses during LDH regeneration. - Abstract: The rehydration process of the calcined MgGa-layered double hydroxides (Ga-LDH) was analyzed at different temperatures and relative humidities. Results clearly showed that Ga-LDH sample presented an excellent regeneration kinetic, in comparison to the aluminum typical one. Different techniques such as X-ray diffraction, infrared spectroscopy and thermal analysis were used to elucidate the presented results

Degradability Enhancement of Poly(Lactic Acid by Stearate-Zn₃Al LDH Nanolayers

Directory of Open Access Journals (Sweden)

Mahboobeh Eili

2012-06-01

Full Text Available Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid/layered double hydroxide (PLA/LDH nanocomposites from PLA and stearate-Zn₃Al LDH. A solution casting method was used to prepare PLA/stearate-Zn₃Al LDH nanocomposites. The anionic clay Zn₃Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn₃Al LDH nanocomposites were studied by X-ray diffraction (XRD, transmission electron microscope (TEM, scanning electron microscope (SEM, thermogravimetric analysis (TGA, tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn₃Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn₃Al LDH nanocomposites showed that the presence of around 1.0–3.0 wt % of the stearate-Zn₃Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn₃Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA.

Improved production of biohydrogen in light-powered Escherichia coli by co-expression of proteorhodopsin and heterologous hydrogenase

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Kim Jaoon YH

2012-01-01

Full Text Available Abstract Background Solar energy is the ultimate energy source on the Earth. The conversion of solar energy into fuels and energy sources can be an ideal solution to address energy problems. The recent discovery of proteorhodopsin in uncultured marine γ-proteobacteria has made it possible to construct recombinant Escherichia coli with the function of light-driven proton pumps. Protons that translocate across membranes by proteorhodopsin generate a proton motive force for ATP synthesis by ATPase. Excess protons can also be substrates for hydrogen (H2 production by hydrogenase in the periplasmic space. In the present work, we investigated the effect of the co-expression of proteorhodopsin and hydrogenase on H2 production yield under light conditions. Results Recombinant E. coli BL21(DE3 co-expressing proteorhodopsin and [NiFe]-hydrogenase from Hydrogenovibrio marinus produced ~1.3-fold more H2 in the presence of exogenous retinal than in the absence of retinal under light conditions (70 μmole photon/(m2·s. We also observed the synergistic effect of proteorhodopsin with endogenous retinal on H2 production (~1.3-fold more with a dual plasmid system compared to the strain with a single plasmid for the sole expression of hydrogenase. The increase of light intensity from 70 to 130 μmole photon/(m2·s led to an increase (~1.8-fold in H2 production from 287.3 to 525.7 mL H2/L-culture in the culture of recombinant E. coli co-expressing hydrogenase and proteorhodopsin in conjunction with endogenous retinal. The conversion efficiency of light energy to H2 achieved in this study was ~3.4%. Conclusion Here, we report for the first time the potential application of proteorhodopsin for the production of biohydrogen, a promising alternative fuel. We showed that H2 production was enhanced by the co-expression of proteorhodopsin and [NiFe]-hydrogenase in recombinant E. coli BL21(DE3 in a light intensity-dependent manner. These results demonstrate that E. coli

[NiFe] hydrogenase structural and functional models: new bio-inspired catalysts for hydrogen evolution; Modeles structuraux et fonctionnels du site actif des hydrogenases [NiFe]: de nouveaux catalyseurs bio-inspires pour la production d'hydrogene

Energy Technology Data Exchange (ETDEWEB)

Oudart, Y

2006-09-15

Hydrogenase enzymes reversibly catalyze the oxidation and production of hydrogen in a range close to the thermodynamic potential. The [NiFe] hydrogenase active site contains an iron-cyano-carbonyl moiety linked to a nickel atom which is in an all sulphur environment. Both the active site originality and the potential development of an hydrogen economy make the synthesis of functional and structural models worthy. To take up this challenge, we have synthesised mononuclear ruthenium models and more importantly, nickel-ruthenium complexes, mimicking some structural features of the [NiFe] hydrogenase active site. Ruthenium is indeed isoelectronic to iron and some of its complexes are well-known to bear hydrides. The compounds described in this study have been well characterised and their activity in proton reduction has been successfully tested. Most of them are able to catalyze this reaction though their electrocatalytic potentials remain much more negative compared to which of platinum. The studied parameters point out the importance of the complexes electron richness, especially of the nickel environment. Furthermore, the proton reduction activity is stable for several hours at good rates. The ruthenium environment seems important for this stability. Altogether, these compounds represent the very first catalytically active [NiFe] hydrogenase models. Important additional results of this study are the synergetic behaviour of the two metals in protons reduction and the evidence of a protonation step as the limiting step of the catalytic cycle. We have also shown that a basic site close to ruthenium improves the electrocatalytic potential of the complexes. (author)

Krypton Derivatization of an O2 -Tolerant Membrane-Bound [NiFe] Hydrogenase Reveals a Hydrophobic Tunnel Network for Gas Transport.

Science.gov (United States)

Kalms, Jacqueline; Schmidt, Andrea; Frielingsdorf, Stefan; van der Linden, Peter; von Stetten, David; Lenz, Oliver; Carpentier, Philippe; Scheerer, Patrick

2016-04-25

[NiFe] hydrogenases are metalloenzymes catalyzing the reversible heterolytic cleavage of hydrogen into protons and electrons. Gas tunnels make the deeply buried active site accessible to substrates and inhibitors. Understanding the architecture and function of the tunnels is pivotal to modulating the feature of O2 tolerance in a subgroup of these [NiFe] hydrogenases, as they are interesting for developments in renewable energy technologies. Here we describe the crystal structure of the O2 -tolerant membrane-bound [NiFe] hydrogenase of Ralstonia eutropha (ReMBH), using krypton-pressurized crystals. The positions of the krypton atoms allow a comprehensive description of the tunnel network within the enzyme. A detailed overview of tunnel sizes, lengths, and routes is presented from tunnel calculations. A comparison of the ReMBH tunnel characteristics with crystal structures of other O2 -tolerant and O2 -sensitive [NiFe] hydrogenases revealed considerable differences in tunnel size and quantity between the two groups, which might be related to the striking feature of O2 tolerance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Is engineering O{sub 2}-tolerant hydrogenases just a matter of reproducing the active sites of the naturally occurring O{sub 2}-resistant enzymes?

Energy Technology Data Exchange (ETDEWEB)

Leroux, Fanny; Liebgott, Pierre-Pol; Kpebe, Arlette; Leger, Christophe; Rousset, Marc; Dementin, Sebastien [CNRS, Laboratoire de Bioenergetique et Ingenierie des Proteines, Institut de Microbiologie de la Mediterranee, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20 (France); Cournac, Laurent; Richaud, Pierre [CEA, DSV, IBEB, Laboratoire de Bioenergetique et Biotechnologie des Bacteries et Microalgues, 13108 Saint-Paul-lez-Durance (France); Aix-Marseille Universite, 3 place Victor-Hugo, 13331 Marseille (France); CNRS, UMR Biologie Vegetale et Microbiologie Environnementales, 13108 Saint-Paul-lez-Durance (France); Burlat, Benedicte; Guigliarelli, Bruno; Bertrand, Patrick [CNRS, Laboratoire de Bioenergetique et Ingenierie des Proteines, Institut de Microbiologie de la Mediterranee, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20 (France); Aix-Marseille Universite, 3 place Victor-Hugo, 13331 Marseille (France)

2010-10-15

Reproducing the naturally occurring O{sub 2}-tolerant hydrogenases is a potential strategy to make the oxygen sensitive enzymes, produced by organisms of biotechnological interest, more resistant. The search for resistance ''hotspots'' that could be transposed into sensitive hydrogenases is underway. Here, we replaced two residues (Y77 and V78) of the oxygen sensitive [NiFe] hydrogenase from Desulfovibrio fructosovorans with Gly and with Cys, respectively, to copy the active site pocket of the resistant membrane-bound [NiFe] enzyme from Ralstonia eutropha and we examined how this affected oxygen sensitivity. The results are discussed in the light of a short review of the recent results dealing with the reactivity of hydrogenases towards oxygen. (author)

Purification and characterization of [Fe]-hydrogenase from high yielding hydrogen-producing strain, Enterobacter cloacae IIT-BT08 (MTCC 5373)

Energy Technology Data Exchange (ETDEWEB)

Dutta, Tumpa; Das, Amit Kumar; Das, Debabrata [Department of Biotechnology, Indian Institute of Technology, Kharagpur, WB 721302 (India)

2009-09-15

Fe-hydrogenase from Enterobacter cloacae IIT-BT08 was purified 1284 fold with specific activity of 335 {mu}mol H{sub 2}/min/mg protein for hydrogen evolution using reduced methyl viologen as an electron-donor at 25 C. The molecular weight of the monomeric enzyme was determined to be 51 kDa by MALDI-ToF mass spectrometry. The PI of the enzyme was {proportional_to}5.6 displaying its acidic nature. The optimal temperature and pH for hydrogen evolution was 37 C and 7-7.2 respectively. The affinity constant, K{sub m} for reduced methyl viologen was 0.57 {+-} 0.03 mM and that of reduced ferredoxin was 0.72 {+-} 0.04 {mu}M. The enzyme contained {proportional_to}11.47 gm-atom Fe/mol of Fe-hydrogenase. Electron paramagnetic resonance analysis ascertained the existence of iron molecules as [4Fe-4S] clusters. The internal amino acid sequences of trypsin digested peptides of hydrogenase as determined by ESI MS/MS Q-ToF showed 80-87% identities with the respective sequences of Clostridium sp. and Trichomonas sp. hydrogenase. (author)

Controlled release of ketorolac through nanocomposite films of hydrogel and LDH nanoparticles

International Nuclear Information System (INIS)

Xu Zhiping; Gu Zi; Cheng Xiaoxi; Rasoul, Firas; Whittaker, Andrew K.; Lu Gaoqing Max

2011-01-01

A novel nanocomposite film for sustained release of anionic ophthalmic drugs through a double-control process has been examined in this study. The film, made as a drug-loaded contact lens, consists principally of a polymer hydrogel of 2-hydroxyethyl methacrylate (HEMA), in whose matrix MgAl-layered double hydroxide (MgAl-LDH) nanoparticles intercalated with the anionic drug are well dispersed. Such nanocomposite films (hydrogel-LDH-drug) contained 0.6–0.8 mg of MgAl-LDH and 0.08–0.09 mg of the ophthalmic drug (ketorolac) in 1.0 g of hydrogel. MgAl-drug-LDH nanoparticles were prepared with the hydrodynamic particle size of 40–200 nm. TEM images show that these nanoparticles are evenly dispersed in the hydrogel matrix. In vitro release tests of hydrogel-LDH-drug in pH 7.4 PBS solution at 32 °C indicate a sustained release profile of the loaded drug for 1 week. The drug release undergoes a rapid initial burst and then a monotonically decreasing rate up to 168 h. The initial burst release is determined by the film thickness and the polymerization conditions, but the following release rate is very similar, with the effective diffusion coefficient being nearly constant (3.0 × 10 −12 m 2 /s). The drug release from the films is mechanistically attributed to anionic exchange and the subsequent diffusion in the hydrogel matrix.

[NiFe] hydrogenase structural and functional models: new bio-inspired catalysts for hydrogen evolution; Modeles structuraux et fonctionnels du site actif des hydrogenases [NiFe]: de nouveaux catalyseurs bio-inspires pour la production d'hydrogene

Energy Technology Data Exchange (ETDEWEB)

Oudart, Y

2006-09-15

Hydrogenase enzymes reversibly catalyze the oxidation and production of hydrogen in a range close to the thermodynamic potential. The [NiFe] hydrogenase active site contains an iron-cyano-carbonyl moiety linked to a nickel atom which is in an all sulphur environment. Both the active site originality and the potential development of an hydrogen economy make the synthesis of functional and structural models worthy. To take up this challenge, we have synthesised mononuclear ruthenium models and more importantly, nickel-ruthenium complexes, mimicking some structural features of the [NiFe] hydrogenase active site. Ruthenium is indeed isoelectronic to iron and some of its complexes are well-known to bear hydrides. The compounds described in this study have been well characterised and their activity in proton reduction has been successfully tested. Most of them are able to catalyze this reaction though their electrocatalytic potentials remain much more negative compared to which of platinum. The studied parameters point out the importance of the complexes electron richness, especially of the nickel environment. Furthermore, the proton reduction activity is stable for several hours at good rates. The ruthenium environment seems important for this stability. Altogether, these compounds represent the very first catalytically active [NiFe] hydrogenase models. Important additional results of this study are the synergetic behaviour of the two metals in protons reduction and the evidence of a protonation step as the limiting step of the catalytic cycle. We have also shown that a basic site close to ruthenium improves the electrocatalytic potential of the complexes. (author)

Dynamic water vapor sorption on Mg(Ga{sup 3+})O mixed oxides: Analysis of the LDH thermal regeneration process

Energy Technology Data Exchange (ETDEWEB)

Bedolla-Valdez, Zaira I.; Ramirez-Solis, Sergio [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito exterior s/n, Cd. Universitaria, Del. Coyoacán, CP 04510, México, DF (Mexico); Prince, Julia [Instituto Mexicano del Petróleo, Eje Central 152, CP 07730, México, DF (Mexico); Lima, Enrique [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito exterior s/n, Cd. Universitaria, Del. Coyoacán, CP 04510, México, DF (Mexico); Pfeiffer, Heriberto, E-mail: pfeiffer@iim.unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito exterior s/n, Cd. Universitaria, Del. Coyoacán, CP 04510, México, DF (Mexico); Valente, Jaime S. [Instituto Mexicano del Petróleo, Eje Central 152, CP 07730, México, DF (Mexico)

2013-02-10

Highlights: ► Ga-LDH regeneration process was analyzed varying the relative humidity. ► Ga-LDH rehydrates faster than aluminum content LDH materials. ► Gallium seems to favor diffusion processeses during LDH regeneration. - Abstract: The rehydration process of the calcined MgGa-layered double hydroxides (Ga-LDH) was analyzed at different temperatures and relative humidities. Results clearly showed that Ga-LDH sample presented an excellent regeneration kinetic, in comparison to the aluminum typical one. Different techniques such as X-ray diffraction, infrared spectroscopy and thermal analysis were used to elucidate the presented results.

Correlation between LDH levels and response to sorafenib in HCC patients: an analysis of the ITA.LI.CA database.

Science.gov (United States)

Sacco, Rodolfo; Mismas, Valeria; Granito, Alessandro; Musettini, Gianna; Masi, Gianluca; Caparello, Chiara; Vivaldi, Caterina; Felder, Martina; Bresci, Giampaolo; Fornaro, Lorenzo

2015-02-24

Lactate dehydrogenase (LDH) is a predictor of clinical outcome in hepatocellular carcinoma (HCC) patients. However, its predictive role in the clinical outcomes of sorafenib treatment has been poorly documented. The correlation between LDH levels and clinical outcomes in HCC patients treated with sorafenib and included in the nationwide Italian database ITA.LI.CA was investigated here. The ITA.LI.CA database contains data for 5,136 HCC patients. All patients treated with sorafenib treatment and with available LDH values were considered. Overall survival (OS) and time to progression (TTP) were compared in patients with LDH levels above and below a defined threshold, determined through an ROC analysis. An explorative analysis investigated the relationship between the variation of LDH levels during treatment and response to sorafenib. Baseline LDH levels were available for 97 patients. The most accurate cutoff value for LDH concentration was 297 U/L. Patients with LDH values above (n=45) and below (n=52) this threshold showed equal OS (12.0 months) and TTP (4.0 months) values. Data on LDH levels during sorafenib treatment were reported for 10 patients. LDH values decreased in 3 patients (mean difference = -219 U/L) who also reported a prolonged OS and TTP versus those with unmodified/increased LDH (OS: NE (not evaluated) vs. 8.0 months, p=0.0083; TTP: 19.0 vs. 3.0 months, p=0.008). The clinical benefits of sorafenib do not seem to be influenced by baseline LDH. According to the results of an explorative analysis, however, a decreased LDH concentration during sorafenib might be associated with improved clinical outcomes.

Synthesis and morphological modification of semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films

Energy Technology Data Exchange (ETDEWEB)

Valente, Jaime S., E-mail: jsanchez@imp.mx [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); López-Salinas, Esteban [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); Prince, Julia [Universidad Anáhuac México Norte, Av. Universidad Anáhuac # 46, Huixquilucan, Edo. de México 52786 (Mexico); González, Ignacio; Acevedo-Peña, Prospero [Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Apdo. Postal 55-534, 09340 México D.F. (Mexico); Ángel, Paz del [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico)

2014-09-15

Layered double hydroxide (LDH) thin films with different chemical compositions (MgZnAl, MgZnGa, MgGaAl) and varying thicknesses were easily prepared by sol–gel method followed by dip-coating. Films were chemically uniform, transparent and well adhered to a conductive indium tin oxide (ITO) substrate. Structure, chemical composition and morphology of the thin films were characterized by XRD-GADDS, SEM-EDS and AFM. Additionally, the semiconducting properties of all the prepared films were studied through the Mott–Schottky relationship; such properties were closely related to the chemical compositions of the film. The films were characterized after electrochemical treatment and important modifications regarding surface morphology, particle and crystal sizes were observed. An in-depth study was conducted in order to investigate the effect of several different electrochemical treatments on the morphology, particle size distribution and crystal size of LDH thin films. Upon electrochemical treatment, the films' surface became smooth and the particles forming the films were transformed from flaky open LDH platelets to uniformly distributed close-packed LDH nanoparticles. - Highlights: • Semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films prepared by sol–gel. • LDH thin films show a turbostratic morphology made up of porous flakes. • Electrochemical treatments change the flaky structure into a nanoparticle array.

LDH-A promotes malignant progression via activation of epithelial-to-mesenchymal transition and conferring stemness in muscle-invasive bladder cancer

Energy Technology Data Exchange (ETDEWEB)

Jiang, Fujin [Department of Urinary Surgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu (China); Department of Urinary Surgery, Huai' an Hospital to Xuzhou Medical University, Huai' an, Jiangsu (China); Ma, Song [Department of Urinary Surgery, Huai' an Hospital to Xuzhou Medical University, Huai' an, Jiangsu (China); Xue, Yubao [Department of Medical Oncology, Huai' an Hospital to Xuzhou Medical University, Huai' an, Jiangsu (China); Hou, Jianquan, E-mail: Jianquanhou@aliyun.com [Department of Urinary Surgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu (China); Zhang, Yongjie, E-mail: zhangyj0818@126.com [Department of Medical Oncology, Huai' an Hospital to Xuzhou Medical University, Huai' an, Jiangsu (China)

2016-01-22

Lactate dehydrogenase-A(LDH-A) is an important rate-limiting enzyme in the Warburg effect. Survival analysis indicated poor clinical outcomes in MIBC with high LDH-A expression. The results of in vitro experiment indicated that LDH-A promotes MIBC cells proliferation, invasion and migration. The positive relationship between LDH-A expression and CSC/EMT markers was confirmed both in invasive bladder cell line and in 136 MIBC specimens. Thus, we conclude that LDH-A may be a promising target for MIBC. - Highlights: • Survival analysis indicated poor clinical outcomes in MIBC with high LDH-A expression. • IHC analysis of 136 MIBC specimens revealed increased LDH-A is correlated with positive Oct4 and negative E-cadherin. • In vitro experiments demonstrated LDH-A promotes MIBC progression by positive regulation of EMT/CSC.

Efficient VEGF targeting delivery of DOX using Bevacizumab conjugated SiO2@LDH for anti-neuroblastoma therapy.

Science.gov (United States)

Zhu, Rongrong; Wang, Zhaoqi; Liang, Peng; He, Xiaolie; Zhuang, Xizhen; Huang, Ruiqi; Wang, Mei; Wang, Qigang; Qian, Yechang; Wang, Shilong

2017-11-01

Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis and is highly expressed in carcinoma, which make it an important target for tumor targeting therapy. Neuroblastoma is the main cause for cancer-related death in children. Like most solid tumors, it is also accompanied with the overexpression of VEGF. Doxorubicin Hydrochloride (DOX), a typical chemotherapeutic agent, exhibits efficient anticancer activities for various cancers. However, DOX, without targeting ability, usually causes severe damage to normal tissues. To overcome the shortages, we designed a novel nano-composite, which is Bevacizumab (Bev) modified SiO 2 @LDH nanoparticles (SiO 2 @LDH-Bev), loading with DOX to achieve targeting ability and curative efficiency. SiO 2 @LDH-DOX and SiO 2 @LDH-Bev-DOX nanoparticles were synthesized and the physicochemical properties were characterized by TEM detection, Zeta potential analysis, FTIR, Raman and XPS analysis. Then in vitro and in vivo anti-neuroblastoma efficiency, targeting ability and mechanisms of anti-carcinoma and anti-angiogenesis of SiO 2 @LDH-Bev-DOX were explored. Our results indicated that we obtained the core-shell structure SiO 2 @LDH-Bev with an average diameter of 253±10nm and the amount of conjugated Bev was 4.59±0.38μg/mg SiO 2 @LDH-Bev. SiO 2 @LDH-Bev-DOX could improve the cellular uptake and the targeting effect of DOX to brain and tumor, enhance the anti-neuroblastoma and anti-angiogenesis efficiency both in vitro and in vivo, and alleviate side effects of DOX sharply, especially hepatic injury. In addition, we also demonstrated that angiogenesis inhibitory effect was mediated by DOX and VEGF triggered signal pathways, including PI3K/Akt, Raf/MEK/ERK, and adhesion related pathways. In summary, SiO 2 @LDH-Bev could be a potential VEGF targeting nanocarrier applied in VEGF positive cancer therapy. This paper explored that a novel core-shell structure nanomaterial SiO 2 @LDH and modified SiO 2 @LDH with

Efficient delivery of anticancer drug MTX through MTX-LDH nanohybrid system

Science.gov (United States)

Oh, Jae-Min; Park, Man; Kim, Sang-Tae; Jung, Jin-Young; Kang, Yong-Gu; Choy, Jin-Ho

2006-05-01

We have been successful to intercalate anticancer drug, methotrexate (MTX), into layered double hydroxides (LDHs), Mg2Al(OH)6(NO3)·0.1H2O, through conventional co-precipitation method. Layered double hydroxides (LDHs) are endowed with great potential for delivery vector, since their cationic layers lead to safe reservation of biofunctional molecules such as drug molecules or genes. And their ion exchangeability and solubility in acidic media (pHosteosarcoma cell culture lines (Saos-2 and MG-63) and the normal one (human fibroblast) were used for in vitro test. The anticancer efficacy of MTX intercalated LDHs (MTX-LDH nanohybrids) was also estimated in vitro by the bioassay such as MTT and BrdU (5-bromo-2-deoxyuridine) with the bone cancer cell culture lines (Saos-2 and MG-63). According to the toxicity test results, LDHs do not harm to both the normal and cancer cells upto the concentration of 500 ug/mL. The anticancer efficacy test for the MTX-LDH nanohybrids turn out to be much more effective in cell suppression compared to the MTX itself. According to the cell-line tests, the MTX-LDH shows same drug efficacy to the MTX itself in spite of the low concentration by ˜5000 times. Such a high cancer suppression effect of MTX-LDH hybrid is surely due to the excellent delivery efficiency of inorganic delivery vector, LDHs.

Detection of the clostridial hydrogenase gene activity as a bio-index in a molasses wastewater bio-hydrogen producing system by real time PCR and FISH/ flow cytometry

International Nuclear Information System (INIS)

Jui-Jen Chang; Ping-Chi Hsu; Chi-Wa Choi; Sian-Jhong Yu; Cheng-Yu Ho; Wei-En Chen; Jiunn-Jyi Lay; Chieh-Chen Huang; Fu-Shyan Wen

2006-01-01

Hydrogenase is a key enzyme that is used by obligate, anaerobic clostridial to produce hydrogen. In this study a fermentative system with molasses wastewater as nutrient was used to produce hydrogen. For establishing the relationship between the vicissitude of clostridial hydrogenase gene activity and the hydrogen production of this system during the culturing period, total cellular RNA isolated at different growing stages were subjected to real time PCR using primer pair, which were designed according to the conserved sequence of clostridial hydrogenase genes. Cell samples at corresponding growing stages were subjected to in situ reverse transcriptase polymerase chain reaction (in situ RT-PCR) using the same primers and then to fluorescence in situ hybridization (FISH) using clostridial hydrogenase gene-specific DNA probe. Those clostridial cells expressed hydrogenase gene activity could be detected by fluorescence microscopy. This is the first time hydrogen-producing activity in a mixed culture could be successfully studied by means of FISH of hydrogenase mRNA. Besides, 16S rDNA was amplified from total cellular DNA analyzed by denaturing gradient gel electrophoresis (DGGE) to reveal the bacterial diversity in the fermentative system; FISH and flow cytometry aiming at 16S rRNA were also carried out to calculate the population of clostridia and total eubacteria in the system. (authors)

The Physiological Functions and Structural Determinants of Catalytic Bias in the [FeFe]-Hydrogenases CpI and CpII of Clostridium pasteurianum Strain W5

Directory of Open Access Journals (Sweden)

Jesse B. Therien

2017-07-01

Full Text Available The first generation of biochemical studies of complex, iron-sulfur-cluster-containing [FeFe]-hydrogenases and Mo-nitrogenase were carried out on enzymes purified from Clostridium pasteurianum (strain W5. Previous studies suggested that two distinct [FeFe]-hydrogenases are expressed differentially under nitrogen-fixing and non-nitrogen-fixing conditions. As a result, the first characterized [FeFe]-hydrogenase (CpI is presumed to have a primary role in central metabolism, recycling reduced electron carriers that accumulate during fermentation via proton reduction. A role for capturing reducing equivalents released as hydrogen during nitrogen fixation has been proposed for the second hydrogenase, CpII. Biochemical characterization of CpI and CpII indicated CpI has extremely high hydrogen production activity in comparison to CpII, while CpII has elevated hydrogen oxidation activity in comparison to CpI when assayed under the same conditions. This suggests that these enzymes have evolved a catalytic bias to support their respective physiological functions. Using the published genome of C. pasteurianum (strain W5 hydrogenase sequences were identified, including the already known [NiFe]-hydrogenase, CpI, and CpII sequences, and a third hydrogenase, CpIII was identified in the genome as well. Quantitative real-time PCR experiments were performed in order to analyze transcript abundance of the hydrogenases under diazotrophic and non-diazotrophic growth conditions. There is a markedly reduced level of CpI gene expression together with concomitant increases in CpII gene expression under nitrogen-fixing conditions. Structure-based analyses of the CpI and CpII sequences reveal variations in their catalytic sites that may contribute to their alternative physiological roles. This work demonstrates that the physiological roles of CpI and CpII are to evolve and to consume hydrogen, respectively, in concurrence with their catalytic activities in vitro, with Cp

The Physiological Functions and Structural Determinants of Catalytic Bias in the [FeFe]-Hydrogenases CpI and CpII of Clostridium pasteurianum Strain W5

Science.gov (United States)

Therien, Jesse B.; Artz, Jacob H.; Poudel, Saroj; Hamilton, Trinity L.; Liu, Zhenfeng; Noone, Seth M.; Adams, Michael W. W.; King, Paul W.; Bryant, Donald A.; Boyd, Eric S.; Peters, John W.

2017-01-01

The first generation of biochemical studies of complex, iron-sulfur-cluster-containing [FeFe]-hydrogenases and Mo-nitrogenase were carried out on enzymes purified from Clostridium pasteurianum (strain W5). Previous studies suggested that two distinct [FeFe]-hydrogenases are expressed differentially under nitrogen-fixing and non-nitrogen-fixing conditions. As a result, the first characterized [FeFe]-hydrogenase (CpI) is presumed to have a primary role in central metabolism, recycling reduced electron carriers that accumulate during fermentation via proton reduction. A role for capturing reducing equivalents released as hydrogen during nitrogen fixation has been proposed for the second hydrogenase, CpII. Biochemical characterization of CpI and CpII indicated CpI has extremely high hydrogen production activity in comparison to CpII, while CpII has elevated hydrogen oxidation activity in comparison to CpI when assayed under the same conditions. This suggests that these enzymes have evolved a catalytic bias to support their respective physiological functions. Using the published genome of C. pasteurianum (strain W5) hydrogenase sequences were identified, including the already known [NiFe]-hydrogenase, CpI, and CpII sequences, and a third hydrogenase, CpIII was identified in the genome as well. Quantitative real-time PCR experiments were performed in order to analyze transcript abundance of the hydrogenases under diazotrophic and non-diazotrophic growth conditions. There is a markedly reduced level of CpI gene expression together with concomitant increases in CpII gene expression under nitrogen-fixing conditions. Structure-based analyses of the CpI and CpII sequences reveal variations in their catalytic sites that may contribute to their alternative physiological roles. This work demonstrates that the physiological roles of CpI and CpII are to evolve and to consume hydrogen, respectively, in concurrence with their catalytic activities in vitro, with CpII capturing excess

Layered double hydroxide/polyethylene terephthalate nanocomposites. Influence of the intercalated LDH anion and the type of polymerization heating method

International Nuclear Information System (INIS)

Herrero, M.; Martinez-Gallegos, S.; Labajos, F.M.; Rives, V.

2011-01-01

Conventional and microwave heating routes have been used to prepare PET-LDH (polyethylene terephthalate-layered double hydroxide) composites with 1-10 wt% LDH by in situ polymerization. To enhance the compatibility between PET and the LDH, terephthalate or dodecyl sulphate had been previously intercalated in the LDH. PXRD and TEM were used to detect the degree of dispersion of the filler and the type of the polymeric composites obtained, and FTIR spectroscopy confirmed that the polymerization process had taken place. The thermal stability of these composites, as studied by thermogravimetric analysis, was enhanced when the microwave heating method was applied. Dodecyl sulphate was more effective than terephthalate to exfoliate the samples, which only occurred for the terephthalate ones under microwave irradiation. - Graphical abstract: Conventional and microwave heating routes were used to prepare PET-LDH (polyethylene terephthalate-layered double hydroxide) composites with 1-10 wt% LDH by in situ polymerization. To enhance the compatibility between PET and the LDH, terephthalate or dodecyl sulphate was previously intercalated into the LDH. The microwave process improves the dispersion and the thermal stability of nanocomposites due to the interaction of the microwave radiation and the dipolar properties of EG and the homogeneous heating. Highlights: → LDH-PET compatibility is enhanced by preintercalation of organic anions. → Dodecylsulphate performance is much better than that of terephthalate. → Microwave heating improves the thermal stability of the composites. → Microwave heating improves as well the dispersion of the inorganic phase.

Using Gas Chromatography/Isotope Ratio Mass Spectrometry to Determine the Fractionation Factor for H2 Production by Hydrogenases

International Nuclear Information System (INIS)

Yang, Hui; Ghandi, H.; Shi, Liang; Kreuzer, Helen W.; Ostrom, Nathaniel; Hegg, Eric L.

2012-01-01

Hydrogenases catalyze the reversible formation of H2, and they are key enzymes in the biological cycling of H2. H isotopes should be a very useful tool in quantifying proton trafficking in biological H2 production processes, but there are several obstacles that have thus far limited the use of this tool. In this manuscript, we describe a new method that overcomes some of these barriers and is specifically designed to measure isotopic fractionation during enzyme-catalyzed H2 evolution. A key feature of this technique is that purified hydrogenases are employed, allowing precise control over the reaction conditions and therefore a high level of precision. A custom-designed high-throughput gas chromatography-isotope ratio mass spectrometer is employed to measure the isotope ratio of the H2. Using this method, we determined that the fractionation factor of H2 production by the (NiFe)-hydrogenase from Desulfivibrio fructosovran is 0.27. This result indicates that, as expected, protons are highly favored over deuterons during H2 evolution. Potential applications of this new method are discussed.

Nickel-centred proton reduction catalysis in a model of [NiFe] hydrogenase

Science.gov (United States)

Brazzolotto, Deborah; Gennari, Marcello; Queyriaux, Nicolas; Simmons, Trevor R.; Pécaut, Jacques; Demeshko, Serhiy; Meyer, Franc; Orio, Maylis; Artero, Vincent; Duboc, Carole

2016-11-01

Hydrogen production through water splitting is one of the most promising solutions for the storage of renewable energy. [NiFe] hydrogenases are organometallic enzymes containing nickel and iron centres that catalyse hydrogen evolution with performances that rival those of platinum. These enzymes provide inspiration for the design of new molecular catalysts that do not require precious metals. However, all heterodinuclear NiFe models reported so far do not reproduce the Ni-centred reactivity found at the active site of [NiFe] hydrogenases. Here, we report a structural and functional NiFe mimic that displays reactivity at the Ni site. This is shown by the detection of two catalytic intermediates that reproduce structural and electronic features of the Ni-L and Ni-R states of the enzyme during catalytic turnover. Under electrocatalytic conditions, this mimic displays high rates for H2 evolution (second-order rate constant of 2.5 × 104 M-1 s-1 turnover frequency of 250 s-1 at 10 mM H+ concentration) from mildly acidic solutions.

Malaria rapid diagnostic tests: Plasmodium falciparum infections with high parasite densities may generate false positive Plasmodium vivax pLDH lines

Directory of Open Access Journals (Sweden)

van Esbroeck Marjan

2010-07-01

Full Text Available Abstract Background Most malaria rapid diagnostic tests (RDTs detect Plasmodium falciparum and an antigen common to the four species. Plasmodium vivax-specific RDTs target P. vivax-specific parasite lactate dehydrogenase (Pv-pLDH. Previous observations of false positive Pv-pLDH test lines in P. falciparum samples incited to the present study, which assessed P. vivax-specific RDTs for the occurrence of false positive Pv-pLDH lines in P. falciparum samples. Methods Nine P. vivax-specific RDTs were tested with 85 P. falciparum samples of high (≥2% parasite density. Mixed P. falciparum/P. vivax infections were ruled out by real-time PCR. The RDTs included two-band (detecting Pv-pLDH, three-band (detecting P. falciparum-antigen and Pv-pLDH and four-band RDTs (detecting P. falciparum, Pv-pLDH and pan-pLDH. Results False positive Pv-pLDH lines were observed in 6/9 RDTs (including two- three- and four-band RDTs. They occurred in the individual RDT brands at frequencies ranging from 8.2% to 29.1%. For 19/85 samples, at least two RDT brands generated a false positive Pv-pLDH line. Sixteen of 85 (18.8% false positive lines were of medium or strong line intensity. There was no significant relation between false positive results and parasite density or geographic origin of the samples. Conclusion False positive Pv-pLDH lines in P. falciparum samples with high parasite density occurred in 6/9 P. vivax-specific RDTs. This is of concern as P. falciparum and P. vivax are co-circulating in many regions. The diagnosis of life-threatening P. falciparum malaria may be missed (two-band Pv-pLDH RDT, or the patient may be treated incorrectly with primaquine (three- or four-band RDTs.

In vitro hydrogen production by glucose dehydrogenase and hydrogenase

Energy Technology Data Exchange (ETDEWEB)

Woodward, J. [Oak Ridge National Lab., TN (United States)

1996-10-01

A new in vitro enzymatic pathway for the generation of molecular hydrogen from glucose has been demonstrated. The reaction is based upon the oxidation of glucose by Thermoplasma acidophilum glucose dehydrogenase with the concomitant oxidation of NADPH by Pyrococcus furiosus hydrogenase. Stoichiometric yields of hydrogen were produced from glucose with continuous cofactor recycle. This simple system may provide a method for the biological production of hydrogen from renewable sources. In addition, the other product of this reaction, gluconic acid, is a high-value commodity chemical.

Synthesis and adsorption properties of hierarchical Fe{sub 3}O{sub 4}@MgAl-LDH magnetic microspheres

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiaoge; Li, Bo; Wen, Xiaogang, E-mail: wenxg@scu.edu.cn [Sichuan University, School of Materials Science and Engineering (China)

2017-04-15

In this study, Fe{sub 3}O{sub 4} microspheres were prepared by a hydrothermal method, and then the synthesized Fe{sub 3}O{sub 4} microspheres were used as template to prepare Fe{sub 3}O{sub 4}@MgAl-LDH composite microspheres by a coprecipitation process. Morphology, composition, and crystal structure of synthesized nanomaterials were characterized by X-ray powder diffractometry, scanning electron microscopy, and Fourier transform infrared spectroscopy technologies. The composite hierarchical microspheres are composed of inner Fe{sub 3}O{sub 4} core and outer MgAl-LDH-nanoflake layer, and the average thickness of MgAl-LDH-nanoflake is about 70 nm. The adsorption property of the products toward congo red was also measured using UV–vis spectrometer. The result demonstrated that the Fe{sub 3}O{sub 4}@MgAl-LDH composite adsorbent could remove 99.8% congo red in 30 min, and the maximum adsorption capacity is about 404.6 mg/g, while congo red removal rate of pure MgAl-LDH and Fe{sub 3}O{sub 4} are only 86.3 and 53.1% in 40 min, respectively, and their adsorption capacity are 345.72 and 220.56 mg/g, respectively. It indicates the composite Fe{sub 3}O{sub 4}@ MgAl-LDH nanomaterials have better adsorption performance than pure Fe{sub 3}O{sub 4} and MgAl-LDH nanomaterials. In addition, the magnetic nanocomposites could be separated easily, and it demonstrated good cycle performance.

Cell-free H-cluster synthesis and [FeFe] hydrogenase activation: all five CO and CN⁻ ligands derive from tyrosine.

Directory of Open Access Journals (Sweden)

Jon M Kuchenreuther

Full Text Available [FeFe] hydrogenases are promising catalysts for producing hydrogen as a sustainable fuel and chemical feedstock, and they also serve as paradigms for biomimetic hydrogen-evolving compounds. Hydrogen formation is catalyzed by the H-cluster, a unique iron-based cofactor requiring three carbon monoxide (CO and two cyanide (CN⁻ ligands as well as a dithiolate bridge. Three accessory proteins (HydE, HydF, and HydG are presumably responsible for assembling and installing the H-cluster, yet their precise roles and the biosynthetic pathway have yet to be fully defined. In this report, we describe effective cell-free methods for investigating H-cluster synthesis and [FeFe] hydrogenase activation. Combining isotopic labeling with FTIR spectroscopy, we conclusively show that each of the CO and CN⁻ ligands derive respectively from the carboxylate and amino substituents of tyrosine. Such in vitro systems with reconstituted pathways comprise a versatile approach for studying biosynthetic mechanisms, and this work marks a significant step towards an understanding of both the protein-protein interactions and complex reactions required for H-cluster assembly and hydrogenase maturation.

Enzymatic and spectroscopic properties of a thermostable [NiFe]‑hydrogenase performing H2-driven NAD+-reduction in the presence of O2.

Science.gov (United States)

Preissler, Janina; Wahlefeld, Stefan; Lorent, Christian; Teutloff, Christian; Horch, Marius; Lauterbach, Lars; Cramer, Stephen P; Zebger, Ingo; Lenz, Oliver

2018-01-01

Biocatalysts that mediate the H 2 -dependent reduction of NAD + to NADH are attractive from both a fundamental and applied perspective. Here we present the first biochemical and spectroscopic characterization of an NAD + -reducing [NiFe]‑hydrogenase that sustains catalytic activity at high temperatures and in the presence of O 2 , which usually acts as an inhibitor. We isolated and sequenced the four structural genes, hoxFUYH, encoding the soluble NAD + -reducing [NiFe]‑hydrogenase (SH) from the thermophilic betaproteobacterium, Hydrogenophilus thermoluteolus TH-1 T (Ht). The HtSH was recombinantly overproduced in a hydrogenase-free mutant of the well-studied, H 2 -oxidizing betaproteobacterium Ralstonia eutropha H16 (Re). The enzyme was purified and characterized with various biochemical and spectroscopic techniques. Highest H 2 -mediated NAD + reduction activity was observed at 80°C and pH6.5, and catalytic activity was found to be sustained at low O 2 concentrations. Infrared spectroscopic analyses revealed a spectral pattern for as-isolated HtSH that is remarkably different from those of the closely related ReSH and other [NiFe]‑hydrogenases. This indicates an unusual configuration of the oxidized catalytic center in HtSH. Complementary electron paramagnetic resonance spectroscopic analyses revealed spectral signatures similar to related NAD + -reducing [NiFe]‑hydrogenases. This study lays the groundwork for structural and functional analyses of the HtSH as well as application of this enzyme for H 2 -driven cofactor recycling under oxic conditions at elevated temperatures. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparative study of the activity of lactate dehydrogenase (LDH) in different forms of disease

International Nuclear Information System (INIS)

Gonzalez Quesada, Jorge; Jorquera Cortez, Rodrigo; Rivera Alvarez, Sonia

2007-01-01

The activity of lactate dehydrogenase (LDH) was determined in the fluid gingival crevicular (FGC) from different sites of the anterior sector of the oral cavity in a clinically healthy subjects, and other with moderate gingivitis and with chronic severe generalized periodontists. Patients were treated and followed for three months, after the which has proceeded to make measurements of activity in the same sites discussed above. The results have showed statistically significant differences when comparing the activity of LDH in healthy individuals, and in other patients, treated by the pathology that presenting. On the other hand, were found without statistically significant differences between patients treated with clinically healthy subjects. The conclusion has been that the activity of LDH could be a quantitative marker for assessing cellular damage and evolution of treatment. (author) [es

A novel platform designed by Au core/inorganic shell structure conjugated onto MTX/LDH for chemo-photothermal therapy.

Science.gov (United States)

Tian, De-Ying; Wang, Wei-Yuan; Li, Shu-Ping; Li, Xiao-Dong; Sha, Zhao-Lin

2016-05-30

A novel platform making up of methotrexate intercalated layered double hydroxide (MTX/LDH) hybrid doped with gold nanoparticles (NPs) may have great potential both in chemo-photothermal therapy and the simultaneous drug delivery. In this paper, a promising platform of Au@PDDA-MTX/LDH was developed for anti-tumor drug delivery and synergistic therapy. Firstly, Au NPs were coated using Layer-by-Layer (LbL) technology by alternate deposition of poly (diallyldimethylammonium chloride) (PDDA) and MTX molecules, and then the resulting core-shell structures (named as Au@PDDA-MTX) were directly conjugated onto the surface of MTX/LDH hybrid by electrostatic attraction to afford Au@PDDA-MTX/LDH NPs. Here MTX was used as both the agent for surface modification and the anti-tumor drug for chemotherapy. The platform of Au@PDDA-MTX/LDH NPs not only had a high drug-loading capacity, but also showed excellent colloidal stability and interesting pH-responsive release profile. In vitro drug release studies demonstrated that MTX released from Au@PDDA-MTX/LDH was relatively slow under normal physiological pH, but it was enhanced significantly at a weak acidic pH value. Furthermore, the combined treatment of cancer cells by using Au@PDDA-MTX/LDH for synergistic hyperthermia ablation and chemotherapy was demonstrated to exhibit higher therapeutic efficacy than either single treatment alone, underscoring the great potential of the platform for cancer therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydrogenase activity in Azospirillum brasilense is inhibited by nitrite, nitric oxide, carbon monoxide, and acetylene

Energy Technology Data Exchange (ETDEWEB)

Tibelius, K.H.; Knowles, R.

1984-10-01

Nitrite, NO, CO, and C/sub 2/H/sub 2/ inhibited O/sub 2/-dependent H/sub 2/ uptake (H/sup 3/H oxidation) in denitrifying Azospirillum brasilense Sp7 grown anaerobically on N/sub 2/O or NO/sub 3//sup -/. The apparent K/sub i/ values for inhibition of O/sub 2/-dependent H/sub 2/ uptake were 20 ..mu..M for NO/sub 2//sup -/, 0.4 ..mu..M for NO, 28 ..mu..M for CO, and 88 ..mu..M for C/sub 2/H/sub 2/. These inhibitors also affected methylene blue-dependent H/sub 2/ uptake, presumably by acting directly on the hydrogenase. Nitrite and NO inhibited H/sub 2/ uptake irreversibly, whereas inhibition due to CO was easily reversed by repeatedly evacuating and backfilling with N/sub 2/. The C/sub 2/H/sub 2/ inhibition was not readily reversed, partly due to difficulty in removing the last traces of this gas from solution. The NO/sub 2//sup -/ inhibition of malate-dependent respiration was readily reversed by repeatedly washing the cells, in contrast to the effect of NO/sub 2//sup -/ on H/sub 2/-dependent respiration. These results suggest that the low hydrogenase activities observed in NO/sub 3//sup -/-grown cultures of A. brasilense may be due to the irreversible inhibition of hydrogenase by NO/sub 2//sup -/ and NO produced by NO/sub 3//sup -/ reduction.

Glyphosate and glufosinate detection at electrogenerated NiAl-LDH thin films

Energy Technology Data Exchange (ETDEWEB)

Khenifi, Aicha [Laboratoire des Materiaux Inorganiques, UMR CNRS 6002, Universite Blaise Pascal, Clermont-Ferrand (France); Laboratoire de physico-chimie des materiaux, catalyse et environnement Usto, Oran, El M' nouar (Algeria); Derriche, Zoubir [Laboratoire de physico-chimie des materiaux, catalyse et environnement Usto, Oran, El M' nouar (Algeria); Forano, Claude; Prevot, Vanessa [Laboratoire des Materiaux Inorganiques, UMR CNRS 6002, Universite Blaise Pascal, Clermont-Ferrand (France); Mousty, Christine, E-mail: Christine.Mousty@univ-bpclermont.fr [Laboratoire des Materiaux Inorganiques, UMR CNRS 6002, Universite Blaise Pascal, Clermont-Ferrand (France); Scavetta, Erika, E-mail: scavetta@fci.unibo.it [Laboratorio di Chimica Analitica, Dipartimento di Chimica Fisica ed Inorganica, Universita degli Studi di Bologna (Italy); Ballarin, Barbara; Guadagnini, Lorella; Tonelli, Domenica [Laboratorio di Chimica Analitica, Dipartimento di Chimica Fisica ed Inorganica, Universita degli Studi di Bologna (Italy)

2009-11-10

An amperometric sensor based on Ni{sub 1-x}Al{sub x}(OH){sub 2}NO{sub 3x}.nH{sub 2}O layered double hydroxide (LDH) has been developed for the electrochemical analysis in one step of two herbicides: glyphosate (N-(phosphonomethyl)glycine, Glyp) and glufosinate ((DL-homoalanine-4-yl)-methylphosphinic acid, Gluf). NiAl-LDH was prepared by coprecipitation or by electrodeposition at the Pt electrode surface. Inorganic films were fully characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Adsorption isotherms of Glyp onto this inorganic lamellar material have been established. Electrocatalytic oxidation of Glyp and Gluf is possible at the Ni{sup 3+} centres of the structure. The electrochemical responses of the NiAl-LDH modified electrode were obtained by cyclic voltammetry and chronoamperometry at 0.49 V/SCE as a function of herbicide concentration in 0.1 M NaOH solution. The electrocatalytic response showed a linear dependence on the Glyp concentration ranging between 0.01 and 0.9 mM with a detection limit of 1 {mu}M and sensitivity 287 mA/M cm{sup 2}. The sensitivity found for Gluf was lower (178 mA/M cm{sup 2}).

The expression of Ldh-c in the skeletal muscle of plateau pika (Ochotona curzoniae enhances adaptation to a hypoxic environment

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Zhi F. An

2017-09-01

Full Text Available The plateau pika (Ochotona curzoniae is a species of sprint-running alpine animals in the Qinghai-Tibet Plateau, which is a harsh highland hypoxic environment. Ldh-c is expressed in the testis, sperm and somatic tissues of plateau pika. To reveal the role and physiological mechanisms of sperm-specific lactate dehydrogenase (LDH-C4, in plateau pika to adapt to hypoxic environment, an adenoviral line of pMultiRNAi-Ldhc was constructed and injected into the bilateral biceps femoris of the hind legs. The swimming times of the pikas, and the Ldh-c expression levels, total LDH activities and ATP levels in skeletal muscle, were measured after the pikas were raised in the trapped site for 5 days. Our results showed that after Ldh-c was silenced, the sprint-running ability (swimming time of the plateau pikas was significant decreased, and the total LDH activities and ATP levels were reduced by 28.21% and 27.88%, respectively. Our results indicated that expression of Ldh-c in the skeletal muscle of plateau pika increased anaerobic glycolysis and enhanced adaptation to highland hypoxic environments.

Reaction Coordinate Leading to H2 Production in [FeFe]-Hydrogenase Identified by Nuclear Resonance Vibrational Spectroscopy and Density Functional Theory.

Science.gov (United States)

Pelmenschikov, Vladimir; Birrell, James A; Pham, Cindy C; Mishra, Nakul; Wang, Hongxin; Sommer, Constanze; Reijerse, Edward; Richers, Casseday P; Tamasaku, Kenji; Yoda, Yoshitaka; Rauchfuss, Thomas B; Lubitz, Wolfgang; Cramer, Stephen P

2017-11-22

[FeFe]-hydrogenases are metalloenzymes that reversibly reduce protons to molecular hydrogen at exceptionally high rates. We have characterized the catalytically competent hydride state (H hyd ) in the [FeFe]-hydrogenases from both Chlamydomonas reinhardtii and Desulfovibrio desulfuricans using 57 Fe nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT). H/D exchange identified two Fe-H bending modes originating from the binuclear iron cofactor. DFT calculations show that these spectral features result from an iron-bound terminal hydride, and the Fe-H vibrational frequencies being highly dependent on interactions between the amine base of the catalytic cofactor with both hydride and the conserved cysteine terminating the proton transfer chain to the active site. The results indicate that H hyd is the catalytic state one step prior to H 2 formation. The observed vibrational spectrum, therefore, provides mechanistic insight into the reaction coordinate for H 2 bond formation by [FeFe]-hydrogenases.

Electrochemistry of Simple Organometallic Models of Iron-Iron Hydrogenases in Organic Solvent and Water.

Science.gov (United States)

Gloaguen, Frederic

2016-01-19

Synthetic models of the active site of iron-iron hydrogenases are currently the subjects of numerous studies aimed at developing H2-production catalysts based on cheap and abundant materials. In this context, the present report offers an electrochemist's view of the catalysis of proton reduction by simple binuclear iron(I) thiolate complexes. Although these complexes probably do not follow a biocatalytic pathway, we analyze and discuss the interplay between the reduction potential and basicity and how these antagonist properties impact the mechanisms of proton-coupled electron transfer to the metal centers. This question is central to any consideration of the activity at the molecular level of hydrogenases and related enzymes. In a second part, special attention is paid to iron thiolate complexes holding rigid and unsaturated bridging ligands. The complexes that enjoy mild reduction potentials and stabilized reduced forms are promising iron-based catalysts for the photodriven evolution of H2 in organic solvents and, more importantly, in water.

Occurrence of H2-Uptake Hydrogenases in Bradyrhizobium sp. (Lupinus) and Their Expression in Nodules of Lupinus spp. and Ornithopus compressus1

Science.gov (United States)

Murillo, Jesús; Villa, Ana; Chamber, Manuel; Ruiz-Argüeso, Tomás

1989-01-01

Fifty-four strains of Bradyrhizobium sp. (Lupinus) from worldwide collections were screened by a colony hybridization method for the presence of DNA sequences homologous to the structural genes of the Bradyrhizobium japonicum hydrogenase. Twelve strains exhibited strong colony hybridization signals, and subsequent Southern blot hybridization experiments showed that they fell into two different groups on the basis of the pattern of EcoRI fragments containing the homology to the hup probe. All strains in the first group (UPM860, UPM861, and 750) expressed uptake hydrogenase activity in symbiosis with Lupinus albus, Lupinus angustifolius, Lupinus luteus, and Ornithopus compressus, but both the rate of H2 uptake by bacteroids and the relative efficiency of N2 fixation (RE = 1 - [H2 evolved in air/acetylene reduced]) by nodules were markedly affected by the legume host. L. angustifolius was the less permissive host for hydrogenase expression in symbiosis with the three strains (average RE = 0.76), and O. compressus was the more permissive (average RE = 1.0). None of the strains in the second group expressed hydrogenase activity in lupine nodules, and only one exhibited low H2-uptake activity in symbiosis with O. compressus. The inability of these putative Hup+ strains to induce hydrogenase activity in lupine nodules is discussed on the basis of the legume host effect. Among the 42 strains showing no homology to the B. japonicum hup-specific probe in the colony hybridization assay, 10 were examined in symbiosis with L. angustifolius. The average RE for these strains was 0.51. However, one strain, IM43B, exhibited high RE values (higher than 0.80) and high levels of hydrogenase activity in symbiosis with L. angustifolius, L. albus, and L. luteus. In Southern blot hybridization experiments, no homology was detected between the B. japonicum hup-specific DNA probe and total DNA from vegetative cells or bacteroids from strain IM43B even under low stringency hybridization

Small-Sized Mg–Al LDH Nanosheets Supported on Silica Aerogel with Large Pore Channels: Textural Properties and Basic Catalytic Performance after Activation

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Lijun Wang

2018-02-01

Full Text Available Layered double hydroxides (LDHs have been widely used as an important subset of solid base catalysts. However, developing low-cost, small-sized LDH nanoparticles with enhanced surface catalytic sites remains a challenge. In this work, silica aerogel (SA-supported, small-sized Mg–Al LDH nanosheets were successfully prepared by one-pot coprecipitation of Mg and Al ions in an alkaline suspension of crushed silica aerogel. The supported LDH nanosheets were uniformly dispersed in the SA substrate with the smallest average radial diameter of 19.2 nm and the thinnest average thickness of 3.2 nm, both dimensions being significantly less than those of the vast majority of LDH nanoparticles reported. The SA/LDH composites also showed large pore volume (up to 1.3 cm3·g and pore diameter (>9 nm, and therefore allow efficient access of reactants to the edge catalytic sites of LDH nanosheets. In a base-catalyzed Henry reaction of benzaldehyde with nitromethane, the SA/LDH catalysts showed high reactant conversions and favorable stability in 6 successive cycles of reactions. The low cost of the SA carrier and LDH precursors, easy preparation method, and excellent catalytic properties make these SA/LDH composites a competitive example of solid-base catalysts.

Improving the Carprofen Solubility: Synthesis of the Zn2Al-LDH Hybrid Compound.

Science.gov (United States)

Capsoni, Doretta; Quinzeni, Irene; Bruni, Giovanna; Friuli, Valeria; Maggi, Lauretta; Bini, Marcella

2018-01-01

The development of efficient strategies for drug delivery is considerably desired. Indeed, often several issues such as the drug solubility, the control of the drug release rate, the targeted delivery of drugs, the drug bioavailability, and the minimization of secondary effects still present great obstacles. Different methodologies have been proposed, but the use of nano-hybrids compounds that combine organic and inorganic substances seems particularly promising. An interesting inorganic host is the layered double hydroxide (LDH) with a sheets structure and formula [M 2+ 1-x M 3+ x (OH) 2 ](A n- ) x/n yH 2 O (M 2+  = Zn, Mg; M 3+  = Al; A n-  = nitrates, carbonates, chlorides). The possibility to exchange these counterions with drug molecules makes these systems ideal candidates for the drug delivery. In this article, we synthesize by co-precipitation method the hybrid compound Carprofen-Zn 2 Al-LDH. Carprofen, a poorly soluble anti-inflammatory drug, could also benefit of the association with a natural antacid such as LDH, to reduce the gastric irritation after its administration. Through X-ray diffraction and Fourier-transformed infrared spectroscopy (FT-IR), we could verify the effective drug intercalation into LDH. The dissolution tests clearly demonstrate a significant improvement of the drug release rate when carprofen is in the form of hybrid compound. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

High-Stacking-Density, Superior-Roughness LDH Bridged with Vertically Aligned Graphene for High-Performance Asymmetric Supercapacitors.

Science.gov (United States)

Guo, Wei; Yu, Chang; Li, Shaofeng; Yang, Juan; Liu, Zhibin; Zhao, Changtai; Huang, Huawei; Zhang, Mengdi; Han, Xiaotong; Niu, Yingying; Qiu, Jieshan

2017-10-01

The high-performance electrode materials with tuned surface and interface structure and functionalities are highly demanded for advanced supercapacitors. A novel strategy is presented to conFigure high-stacking-density, superior-roughness nickel manganese layered double hydroxide (LDH) bridged by vertically aligned graphene (VG) with nickel foam (NF) as the conductive collector, yielding the LDH-NF@VG hybrids for asymmetric supercapacitors. The VG nanosheets provide numerous electron transfer channels for quick redox reactions, and well-developed open structure for fast mass transport. Moreover, the high-stacking-density LDH grown and assembled on VG nanosheets result in a superior hydrophilicity derived from the tuned nano/microstructures, especially microroughness. Such a high stacking density with abundant active sites and superior wettability can be easily accessed by aqueous electrolytes. Benefitting from the above features, the LDH-NF@VG can deliver a high capacitance of 2920 F g -1 at a current density of 2 A g -1 , and the asymmetric supercapacitor with the LDH-NF@VG as positive electrode and activated carbon as negative electrode can deliver a high energy density of 56.8 Wh kg -1 at a power density of 260 W kg -1 , with a high specific capacitance retention rate of 87% even after 10 000 cycles. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ANTS-anchored Zn-Al-CO3-LDH particles as fluorescent probe for sensing of folic acid

International Nuclear Information System (INIS)

Liu, Pengfei; Liu, Dan; Liu, Yanhuan; Li, Lei

2016-01-01

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO 3 -layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn 2+ ions of Zn-Al-CO 3 -LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO 3 -LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO 3 -LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO 3 groups in ANTS-anchored on the surface of Zn-Al-CO 3 -LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO 3 -LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

Protonation/reduction dynamics at the [4Fe-4S] cluster of the hydrogen-forming cofactor in [FeFe]-hydrogenases.

Science.gov (United States)

Senger, Moritz; Mebs, Stefan; Duan, Jifu; Shulenina, Olga; Laun, Konstantin; Kertess, Leonie; Wittkamp, Florian; Apfel, Ulf-Peter; Happe, Thomas; Winkler, Martin; Haumann, Michael; Stripp, Sven T

2018-01-31

The [FeFe]-hydrogenases of bacteria and algae are the most efficient hydrogen conversion catalysts in nature. Their active-site cofactor (H-cluster) comprises a [4Fe-4S] cluster linked to a unique diiron site that binds three carbon monoxide (CO) and two cyanide (CN - ) ligands. Understanding microbial hydrogen conversion requires elucidation of the interplay of proton and electron transfer events at the H-cluster. We performed real-time spectroscopy on [FeFe]-hydrogenase protein films under controlled variation of atmospheric gas composition, sample pH, and reductant concentration. Attenuated total reflection Fourier-transform infrared spectroscopy was used to monitor shifts of the CO/CN - vibrational bands in response to redox and protonation changes. Three different [FeFe]-hydrogenases and several protein and cofactor variants were compared, including element and isotopic exchange studies. A protonated equivalent (HoxH) of the oxidized state (Hox) was found, which preferentially accumulated at acidic pH and under reducing conditions. We show that the one-electron reduced state Hred' represents an intrinsically protonated species. Interestingly, the formation of HoxH and Hred' was independent of the established proton pathway to the diiron site. Quantum chemical calculations of the respective CO/CN - infrared band patterns favored a cysteine ligand of the [4Fe-4S] cluster as the protonation site in HoxH and Hred'. We propose that proton-coupled electron transfer facilitates reduction of the [4Fe-4S] cluster and prevents premature formation of a hydride at the catalytic diiron site. Our findings imply that protonation events both at the [4Fe-4S] cluster and at the diiron site of the H-cluster are important in the hydrogen conversion reaction of [FeFe]-hydrogenases.

Transcription and Regulation of the Bidirectional Hydrogenase in the Cyanobacterium Nostoc sp. Strain PCC 7120▿

Science.gov (United States)

Sjöholm, Johannes; Oliveira, Paulo; Lindblad, Peter

2007-01-01

The filamentous, heterocystous cyanobacterium Nostoc sp. strain PCC 7120 (Anabaena sp. strain PCC 7120) possesses an uptake hydrogenase and a bidirectional enzyme, the latter being capable of catalyzing both H2 production and evolution. The completely sequenced genome of Nostoc sp. strain PCC 7120 reveals that the five structural genes encoding the bidirectional hydrogenase (hoxEFUYH) are separated in two clusters at a distance of approximately 8.8 kb. The transcription of the hox genes was examined under nitrogen-fixing conditions, and the results demonstrate that the cluster containing hoxE and hoxF can be transcribed as one polycistronic unit together with the open reading frame alr0750. The second cluster, containing hoxU, hoxY, and hoxH, is transcribed together with alr0763 and alr0765, located between the hox genes. Moreover, alr0760 and alr0761 form an additional larger operon. Nevertheless, Northern blot hybridizations revealed a rather complex transcription pattern in which the different hox genes are expressed differently. Transcriptional start points (TSPs) were identified 66 and 57 bp upstream from the start codon of alr0750 and hoxU, respectively. The transcriptions of the two clusters containing the hox genes are both induced under anaerobic conditions concomitantly with the induction of a higher level of hydrogenase activity. An additional TSP, within the annotated alr0760, 244 bp downstream from the suggested translation start codon, was identified. Electrophoretic mobility shift assays with purified LexA from Nostoc sp. strain PCC 7120 demonstrated specific interactions between the transcriptional regulator and both hox promoter regions. However, when LexA from Synechocystis sp. strain PCC 6803 was used, the purified protein interacted only with the promoter region of the alr0750-hoxE-hoxF operon. A search of the whole Nostoc sp. strain PCC 7120 genome demonstrated the presence of 216 putative LexA binding sites in total, including recA and rec

New way for iron introduction in LDH matrix used as catalysts for Friedel–Crafts reactions

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S. Kerchiche

2017-02-01

Full Text Available The alkylation of toluene, reaction employing benzyl chloride as the alkylating agent over basic hydrotalcite materials: Fe–Mg–Al-LDH prepared by different synthesis methods, including the method of co-precipitation, impregnation and a new method called the method of intercalation by anion exchange in the lamellar space of the host structure LDH. Our prepared solids were characterized by chemical analysis, XRD analysis, BET method and thermogravimetric analysis (TGA and tested in the alkylation of toluene by benzyl chloride reaction. Fe–Mg–Al-LDH clay without or with calcination (at 773 K has been investigated. The catalyst derived from the hydrotalcite by its calcination at 773 K shows high catalytic activity for the alkylation of toluene and other aromatic compounds. The catalytically active species present in the catalyst in its most active form are the oxides of iron on the catalyst surface.

ANTS-anchored Zn-Al-CO{sub 3}-LDH particles as fluorescent probe for sensing of folic acid

Energy Technology Data Exchange (ETDEWEB)

Liu, Pengfei; Liu, Dan; Liu, Yanhuan [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Lei, E-mail: lilei@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China)

2016-09-15

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO{sub 3}-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn{sup 2+} ions of Zn-Al-CO{sub 3}-LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO{sub 3}-LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO{sub 3} groups in ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO{sub 3}-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

New DC conductivity spectra of Zn–Al layered double hydroxide (Zn–Al–NO3–LDH and its calcined product of ZnO phase

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Abdullah Ahmed Ali Ahmed

2017-05-01

Full Text Available Zn–Al–NO3–LDH nanostructure was synthesized via the coprecipitation method at molar ratio Zn2+/Al3+ = 4 and pH = 7. The resultant sample was thermally treated at calcined temperatures of 50, 100, 150, 200, 250 and 300 °C. The layered structure of the Zn–Al–NO3–LDH samples was stable below the calcination temperature 200 °C as shown in powder X-ray diffraction (PXRD patterns of calcined samples. The calcination products showed a collapse of LDH structure and ZnO phase was formed at 200 °C and above. The dielectric spectroscopy of LDH was explained using anomalous low frequency dispersion (ALFD due to the low mobility of LDH carriers. The conductivity spectra of LDH can be theoretically described according to the effective phase within the calcination products of LDH. In the comparison with previously researches, this study presented higher values of DC conductivity for all studied samples.

Determination of lactate dehydrogenase (LDH and Bcr-Abl transcript in the follow-up of patients with chronic myeloid leukemia = Determinação da lactate desidrogenase (LDH e do transcrito Bcr-Abl em pacientes com leucemia mielóide crônica

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Roberto Iemitsu Tatakihara

2010-07-01

Full Text Available Chronic myeloid leukemia (CML is a malignant myeloproliferative disorder that originates from a pluripotent stem cell characterized by abnormal release of the expanded, malignant stem cell clone from the bone marrow into the bloodstream. The vast majority of patients with CML present Bcr-Abl transcripts. Lactate dehydrogenase (LDH is considered a biochemical marker common for tumor growth, anaerobic glycolysis and has been considered a poor prognostic factor for acute myeloid leukemia. Therefore, this study aimed to evaluate the concentration of LDH in plasma and the detection of the Bcr-Abl transcripts in patients with CML and healthy donors. We analyzed 22 patients demonstrably diagnosed with CML and 56 healthy donors. LDH concentration in plasma was higher in patients with CML. All patients with CML in this study were under treatment, but even so four patients had the Bcr-Abl (b3a2 transcript in peripheral blood. Two out of the four patients with b3a2 showed higher LDH (486 U L-1 and 589 U L-1. Thus, although the study was conducted with small numbers of samples, it is possible to suggest therapy alteration for two patients who presented transcript b3a2 in the peripheral blood samples and whose LDH concentration was high, in order to improve the disease. Leucemia mieloide crônica (LMC é uma desordem mieloproliferativa maligna que é originada de célula-tronco pluripotente caracterizada por expansão anormal, maligna de clones de células tronco da medula óssea na circulação. A grande maioria dos pacientes com LMC apresentam transcritos Bcr-Abl. Lactato desidrogenase (LDH,considerado um marcador bioquímico para crescimento tumoral, glicólise anaeróbica, e tem sido considerado um fator de pior prognóstico da LMC. Portanto, este estudo visa avaliar a concentraçãode LDH no plasma e a detecção do transcrito Bcr-Abl em 22 pacientes com LMC e 56 indivíduos saudáveis. Foram avaliados 22 pacientes com LMC e 56 doadores saudáveis. A

Effects and Mechanism of Atmospheric-Pressure Dielectric Barrier Discharge Cold Plasma on Lactate Dehydrogenase (LDH) Enzyme

Science.gov (United States)

Zhang, Hao; Xu, Zimu; Shen, Jie; Li, Xu; Ding, Lili; Ma, Jie; Lan, Yan; Xia, Weidong; Cheng, Cheng; Sun, Qiang; Zhang, Zelong; Chu, Paul K.

2015-05-01

Proteins are carriers of biological functions and the effects of atmospheric-pressure non-thermal plasmas on proteins are important to applications such as sterilization and plasma-induced apoptosis of cancer cells. Herein, we report our detailed investigation of the effects of helium-oxygen non-thermal dielectric barrier discharge (DBD) plasmas on the inactivation of lactate dehydrogenase (LDH) enzyme solutions. Circular dichroism (CD) and dynamic light scattering (DLS) indicate that the loss of activity stems from plasma-induced modification of the secondary molecular structure as well as polymerization of the peptide chains. Raising the treatment intensity leads to a reduced alpha-helix content, increase in the percentage of the beta-sheet regions and random sequence, as well as gradually decreasing LDH activity. However, the structure of the LDH plasma-treated for 300 seconds exhibits a recovery trend after storage for 24 h and its activity also increases slightly. By comparing direct and indirect plasma treatments, plasma-induced LDH inactivation can be attributed to reactive species (RS) in the plasma, especially ones with a long lifetime including hydrogen peroxide, ozone, and nitrate ion which play the major role in the alteration of the macromolecular structure and molecular diameter in lieu of heat, UV radiation, and charged particles.

Electrostatic Self-Assembly of Sandwich-Like CoAl-LDH/Polypyrrole/Graphene Nanocomposites with Enhanced Capacitive Performance.

Science.gov (United States)

Zhang, Yu; Du, Dongfeng; Li, Xuejin; Sun, Hongman; Li, Li; Bai, Peng; Xing, Wei; Xue, Qingzhong; Yan, Zifeng

2017-09-20

A novel sandwich-like composite with ultrathin CoAl-layered double hydroxide (LDH) nanoplates electrostatically assembled on both sides of two-dimensional polypyrrole/graphene (PG) substrate has been successfully fabricated using facile hydrothermal techniques. The PG not only serves as an excellent conductive and structural scaffold to enhance the transmission of electrons and prevent aggregation of CoAl-LDH nanoplates but also contributes to the enhancement of the specific capacitance. Owing to the homogeneous dispersion of CoAl-LDH nanoplates and its intimate interaction with PG substrate, the resulting CoAl-LDH/PG nanocomposite material exhibits excellent capacitive performance, for example, enhanced gravimetric specific capacitance (864 F g -1 at 1 A g -1 ), high rate performance (75% retention at 20 A g -1 ), and excellent cycle life (almost no degradation in supercapacitor performance after 5000 cycles) in aqueous KOH solution. Furthermore, the assembled asymmetric capacitor is able to deliver a superhigh energy density of 46.8 Wh kg -1 at 1.2 kW kg -1 and maintain 90.1% of its initial capacitance after 10 000 cycles. These results indicate a rational assembly strategy toward a high-performance pseudocapacitive electrode material with excellent rate performance, high specific capacitance, and outstanding cycle stability.

Requirements for construction of a functional hybrid complex of photosystem I and [NiFe]-hydrogenase.

Science.gov (United States)

Schwarze, Alexander; Kopczak, Marta J; Rögner, Matthias; Lenz, Oliver

2010-04-01

The development of cellular systems in which the enzyme hydrogenase is efficiently coupled to the oxygenic photosynthesis apparatus represents an attractive avenue to produce H(2) sustainably from light and water. Here we describe the molecular design of the individual components required for the direct coupling of the O(2)-tolerant membrane-bound hydrogenase (MBH) from Ralstonia eutropha H16 to the acceptor site of photosystem I (PS I) from Synechocystis sp. PCC 6803. By genetic engineering, the peripheral subunit PsaE of PS I was fused to the MBH, and the resulting hybrid protein was purified from R. eutropha to apparent homogeneity via two independent affinity chromatographical steps. The catalytically active MBH-PsaE (MBH(PsaE)) hybrid protein could be isolated only from the cytoplasmic fraction. This was surprising, since the MBH is a substrate of the twin-arginine translocation system and was expected to reside in the periplasm. We conclude that the attachment of the additional PsaE domain to the small, electron-transferring subunit of the MBH completely abolished the export competence of the protein. Activity measurements revealed that the H(2) production capacity of the purified MBH(PsaE) fusion protein was very similar to that of wild-type MBH. In order to analyze the specific interaction of MBH(PsaE) with PS I, His-tagged PS I lacking the PsaE subunit was purified via Ni-nitrilotriacetic acid affinity and subsequent hydrophobic interaction chromatography. Formation of PS I-hydrogenase supercomplexes was demonstrated by blue native gel electrophoresis. The results indicate a vital prerequisite for the quantitative analysis of the MBH(PsaE)-PS I complex formation and its light-driven H(2) production capacity by means of spectroelectrochemistry.

Epilepsy treatment. Targeting LDH enzymes with a stiripentol analog to treat epilepsy

OpenAIRE

Kim, Andrew J.

2015-01-01

Researchers at Okayama University, Japan showed lactate dehydrogenase (LDH) inhibition suppresses neuronal excitation in vitro, reduces EEG discharges and seizures in rodent models, and may provide a novel mechanism for anticonvulsant medications in human patients.

Synthesis and characterization of LDH/Ppi composite and its application as adsorbent of 2,4-dichlorophenoxyacetic (herbicide)

International Nuclear Information System (INIS)

Pacheco, I.S.; Oliveira, R.S.; Girotto, L.G.; Freitas, L.L. de; Amaral, F.A. do; Canobre, S.C.

2016-01-01

This work had as main objective the synthesis and characterization of LDH [Co-Al-Cl] method by hydrolysis of urea and then its synthesized polypyrrole coating by chemically targeting the application as adsorbent dichlorophenoxyacetic acid (2,4-D). The x-ray diffractogram of well defined showed diffraction peaks corresponding to the planes 003, 006, 009 and 110 which allow them to rhombohedral indexes and lamellar structure. The composite LDH / Ppi had a percentage of 49% herbicide retention in aqueous solution. From the investigated adsorption isotherm models that more fit the experimental data was the Freundlich, so it could be inferred that the interaction between the LDH / Ppi and the herbicide was physical, ie an rapid, reversible adsorption and does not specify. (author)

Structural Mimics of the [Fe]-Hydrogenase: A Complete Set for Group VIII Metals.

Science.gov (United States)

Barik, Chandan Kr; Ganguly, Rakesh; Li, Yongxin; Leong, Weng Kee

2018-06-18

A set of structural mimics of the [Fe]-hydrogenase active site comprising all the group VIII metals, viz., [M(2-NHC(O)C 5 H 4 N)(CO) 2 (2-S-C 5 H 4 N)], has been synthesized. They exist as a mixture of isomers in solution, and the relative stability of the isomers depends on the nature of the metal and the substituent at the 6-position of the pyridine ligand.

High-Performance Flexible Asymmetric Supercapacitor Based on CoAl-LDH and rGO Electrodes

Science.gov (United States)

Li, Shuoshuo; Cheng, Pengpeng; Luo, Jiaxian; Zhou, Dan; Xu, Weiming; Li, Jingwei; Li, Ruchun; Yuan, Dingsheng

2017-07-01

A flexible asymmetric supercapacitor (ASC) based on a CoAl-layered double hydroxide (CoAl-LDH) electrode and a reduced graphene oxide (rGO) electrode was successfully fabricated. The CoAl-LDH electrode as a positive electrode was synthesized by directly growing CoAl-LDH nanosheet arrays on a carbon cloth (CC) through a facile hydrothermal method, and it delivered a specific capacitance of 616.9 F g-1 at a current density of 1 A g-1. The rGO electrode as a negative electrode was synthesized by coating rGO on the CC via a simple dip-coating method and revealed a specific capacitance of 110.0 F g-1 at a current density of 2 A g-1. Ultimately, the advanced ASC offered a broad voltage window (1.7 V) and exhibited a high superficial capacitance of 1.77 F cm-2 at 2 mA cm-2 and a high energy density of 0.71 mWh cm-2 at a power density of 17.05 mW cm-2, along with an excellent cycle stability (92.9% capacitance retention over 8000 charge-discharge cycles).

Topotactic intercalation of a bulky organic anion (thiacalix[4]arene) into LDH through an osmotic swelling/restoration reaction in formamide.

Science.gov (United States)

Huang, Gailing; Ma, Shulan; Zhao, Xinhua; Yang, Xiaojing; Ooi, Kenta

2009-01-21

Utilizing the osmotic swelling of LDH in formamide, for the first time, the bulky thiacalix[4]arene anion is introduced, leading to the recovery of LDH layers, and the hexagonal prism morphology of the precursor is well retained.

Using in vitro maturation and cell-free expression to explore [FeFe] hydrogenase activation and protein scaffolding requirements

Energy Technology Data Exchange (ETDEWEB)

Swartz, James [Stanford Univ., CA (United States)

2017-01-25

Final Project Report describing work to elucidate mechanisms for the activation of [FeFe]-hydrogenases and to explore the impact of the polypeptide scaffolding on the function of the Fe-S redox and catalytic centers with emphasis on improving oxygen tolerance.

Fabrication of Flexible Arrayed Lactate Biosensor Based on Immobilizing LDH-NAD+ on NiO Film Modified by GO and MBs

Science.gov (United States)

Yan, Siao-Jie; Liao, Yi-Hung; Lai, Chih-Hsien; Wu, You-Xiang; Wu, Cian-Yi; Chen, Hsiang-Yi; Huang, Hong-Yu; Wu, Tong-Yu

2017-01-01

We proposed the flexible arrayed lactate biosensor based on immobilizing l-lactate dehydrogenase (LDH) and nicotinamide adenine dinucleotide (NAD+) on nickel oxide (NiO) film, and which the average sensitivity could be enhanced by using graphene oxide (GO) and magnetic beads (MBs). By using GO and MBs, it exhibits excellent sensitivity (45.397 mV/mM) with a linearity of 0.992 in a range of 0.2 mM to 3 mM. According to the results of electrochemical impedance spectroscopy (EIS), the electron transfer resistance of LDH-NAD+-MBs/GPTS/GO/NiO film was smaller than those of LDH-NAD+/GPTS/GO/NiO film and LDH-NAD+/GPTS/NiO film, and it presented the outstanding electron transfer ability. After that, the limit of detection, anti-interference effect and bending test were also investigated. PMID:28704960

Fabrication of Flexible Arrayed Lactate Biosensor Based on Immobilizing LDH-NAD+ on NiO Film Modified by GO and MBs

Directory of Open Access Journals (Sweden)

Jung-Chuan Chou

2017-07-01

Full Text Available We proposed the flexible arrayed lactate biosensor based on immobilizing l-lactate dehydrogenase (LDH and nicotinamide adenine dinucleotide ( NAD + on nickel oxide (NiO film, and which the average sensitivity could be enhanced by using graphene oxide (GO and magnetic beads (MBs. By using GO and MBs, it exhibits excellent sensitivity (45.397 mV/mM with a linearity of 0.992 in a range of 0.2 mM to 3 mM. According to the results of electrochemical impedance spectroscopy (EIS, the electron transfer resistance of LDH- NAD + -MBs/GPTS/GO/NiO film was smaller than those of LDH-NAD+/GPTS/GO/NiO film and LDH- NAD + /GPTS/NiO film, and it presented the outstanding electron transfer ability. After that, the limit of detection, anti-interference effect and bending test were also investigated.

Role of Phase Composition of PEO Coatings on AA2024 for In-Situ LDH Growth

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Maria Serdechnova

2017-11-01

Full Text Available Plasma electrolytic oxidation (PEO is an environmentally friendly anodizing technique leading to the formation of a ceramic-like coatings under high-voltage discharges. Layered double hydroxides (LDHs were grown directly on γ, α, and amorphous Al2O3 powders, respectively, in order to investigate the phase responsible for in-situ LDH growth on PEO coating. Furthermore, it is shown that LDH growth is limited by the high tortuosity of the PEO layer and the accessibility of Al ( OH 4 − anions from the substrate covered with thin amorphous aluminum oxide, through the pores.

Antibodies against Clonorchis sinensis LDH could cross-react with LDHB localizing on the plasma membrane of human hepatocarcinoma cell SMMC-7721 and induce apoptosis.

Science.gov (United States)

Song, Tianzhang; Gan, Wenjia; Chen, Jintao; Huang, Lilin; Yin, Hongling; He, Tailong; Huang, Huaiqiu; Hu, Xuchu

2016-04-01

Lactate dehydrogenase (LDH) is a terminal enzyme in anaerobic glycolytic pathway. It widely exists in various organisms and is in charge of converting the glycolysis product pyruvic acid to lactic acid. Most parasites, including Clonorchis sinensis, predominantly depend on glycolysis to provide energy. Bioinformatic analysis predicts that the LDHs from many species have more than one transmembrane region, suggesting that it may be a membrane protein. C. sinensis LDH (CsLDH) has been confirmed as a transmembrane protein mainly located in the tegument. The antibodies against CsLDH can inhibit the worm's energy metabolism, kill the worm, and may have the same effects on human cancer cells. In this study, we cloned and characterized human LDHA (HsLDHA), HsLDHB, and CsLDH. Semi-quantitative real-time RCP showed that HsLDHB only existed in hepatocarcinoma cell SMMC-7721. Confocal microscopy and Western blot experiments revealed that HsLDHB was localized in the plasma membrane of SMMC-7721 cells, and the antibodies against CsLDH could cross-react with it. This cross-reaction could inhibit the enzymatic activity of HsLDHB. The cancer cells co-cultured with anti-CsLDH sera showed a significant decrease in cell proliferation rate and increases in caspase 9 and reactive oxygen species (ROS) levels. Therefore, anti-CsLDH antibodies can induce the apoptosis of cancer cells SMMC-7721 and may serve as a new tool to inhibit tumor.

Pectins filled with LDH-antimicrobial molecules: preparation, characterization and physical properties.

Science.gov (United States)

Gorrasi, Giuliana; Bugatti, Valeria; Vittoria, Vittoria

2012-06-05

Nanohybrids of layered double hydroxide (LDH) with intercalated active molecules: benzoate, 2,4-dichlorobenzoate, para-hydroxybenzoate and ortho-hydroxybenzoate, were incorporated into pectins from apples through high energy ball milling in the presence of water. Cast films were obtained and analysed. X-ray diffraction analysis showed a complete destructuration of all nanohybrids in the pectin matrix. Thermogravimetric analysis showed a better thermal resistance of pectin in the presence of fillers, especially para-hydroxybenzoate and ortho-hydroxybenzoate. Mechanical properties showed an improvement of elastic modulus in particular for LDH-para-hydroxybenzoate nanohybrid, due probably to a better interaction between pectin matrix and nanohybrid layers. Barrier properties (sorption and diffusion) to water vapour showed improvement in the dependence on the intercalated active molecule, the best improvement was achieved for composites containing para-hydroxybenzoate molecules, suggesting that the interaction between the filler phase and the polymer plays an important role in sorption and diffusion phenomena. Incorporation of these active molecules gave antimicrobial properties to the composite films giving opportunities in the field of active packaging. Copyright © 2012 Elsevier Ltd. All rights reserved.

Tailoring the morphology followed by the electrochemical performance of NiMn-LDH nanosheet arrays through controlled Co-doping for high-energy and power asymmetric supercapacitors.

Science.gov (United States)

Singh, Saurabh; Shinde, Nanasaheb M; Xia, Qi Xun; Gopi, Chandu V V M; Yun, Je Moon; Mane, Rajaram S; Kim, Kwang Ho

2017-10-14

Herein, we tailor the surface morphology of nickel-manganese-layered double hydroxide (NiMn-LDH) nanostructures on 3D nickel-foam via a step-wise cobalt (Co)-doping hydrothermal chemical process. At the 10% optimum level of Co-doping, we noticed a thriving tuned morphological pattern of NiMn-LDH nanostructures (NiCoMn-LDH (10%)) in terms of the porosity of the nanosheet (NS) arrays which not only improves the rate capability as well as cycling stability, but also demonstrates nearly two-fold specific capacitance enhancement compared to Co-free and other NiCoMn-LDH electrodes with a half-cell configuration in 3 M KOH, suggesting that Co-doping is indispensable for improving the electrochemical performance of NiMn-LDH electrodes. Moreover, when this high performing NiCoMn-LDH (10%) electrode is employed as a cathode material to fabricate an asymmetric supercapacitor (ASC) device with reduced graphene oxide (rGO) as an anode material, excellent energy storage performance (57.4 Wh kg -1 at 749.9 W kg -1 ) and cycling stability (89.4% capacitive retention even after 2500 cycles) are corroborated. Additionally, we present a demonstration of illuminating a light emitting diode for 600 s with the NiCoMn-LDH (10%)//rGO ASC device, evidencing the potential of the NiCoMn-LDH (10%) electrode in fabricating energy storage devices.

Radioassay for hydrogenase activity in viable cells and documentation of aerobic hydrogen-consuming bacteria living in extreme environments

International Nuclear Information System (INIS)

Schink, B.; Lupton, F.S.; Zeikus, J.G.

1983-01-01

An isotopic tracer assay based on the hydrogenase-dependent formation of tritiated water from tritium gas was developed for in life analysis of microbial hydrogen transformation. This method allowed detection of bacterial hydrogen metabolism in pure cultures or in natural samples obtained from aquatic ecosystems. A differentiation between chemical-biological and aerobic-anaerobic hydrogen metabolism was established by variation of the experimental incubation temperature or by addition of selective inhibitors. Hydrogenase activity was shown to be proportional to the consumption or production of hydrogen by cultures of Desulfovibrio vulgaris, Clostridium pasteurianum, and Methanosarcina barkeri. This method was applied, in connection with measurements of free hydrogen and most-probable-number enumerations, in aerobic natural source waters to establish the activity and document the ecology of hydrogen-consuming bacteria in extreme acid, thermal, or saline environments. The utility of the assay is based in part on the ability to quantify bacterial hydrogen transformation at natural hydrogen partial pressures, without the use of artificial electron acceptors

Selective Oxidation of Glycerol with 3% H2O2 Catalyzed by LDH-Hosted Cr(III Complex

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Gongde Wu

2015-11-01

Full Text Available A series of layered double hydroxides (LDHs –hosted sulphonato-salen Cr(III complexes were prepared and characterized by various physico-chemical measurements, such as Fourier transform infrared spectroscopy (FTIR, ultraviolet-visible spectroscopy (UV-Vis, powder X-ray diffraction (XRD, transmission electron microscope (TEM, scanning electron microscope (SEM and elemental analysis. Additionally, their catalytic performances were investigated in the selective oxidation of glycerol (GLY using 3% H2O2 as an oxidant. It was found that all the LDH-hosted Cr(III complexes exhibited significantly enhanced catalytic performance compared to the homogeneous Cr(III complex. Additionally, it was worth mentioning that the metal composition of LDH plates played an important role in the catalytic performances of LDH-hosted Cr(III complex catalysts. Under the optimal reaction conditions, the highest GLY conversion reached 85.5% with 59.3% of the selectivity to 1,3-dihydroxyacetone (DHA. In addition, the catalytic activity remained after being recycled five times.

Disclosure of key stereoelectronic factors for efficient H2 binding and cleavage in the active site of [NiFe]-hydrogenases.

Science.gov (United States)

Bruschi, Maurizio; Tiberti, Matteo; Guerra, Alessandro; De Gioia, Luca

2014-02-05

A comparative analysis of a series of DFT models of [NiFe]-hydrogenases, ranging from minimal NiFe clusters to very large systems including both the first and second coordination sphere of the bimetallic cofactor, was carried out with the aim of unraveling which stereoelectronic properties of the active site of [NiFe]-hydrogenases are crucial for efficient H2 binding and cleavage. H2 binding to the Ni-SIa redox state is energetically favored (by 4.0 kcal mol(-1)) only when H2 binds to Ni, the NiFe metal cluster is in a low spin state, and the Ni cysteine ligands have a peculiar seesaw coordination geometry, which in the enzyme is stabilized by the protein environment. The influence of the Ni coordination geometry on the H2 binding affinity was then quantitatively evaluated and rationalized analyzing frontier molecular orbitals and populations. Several plausible reaction pathways leading to H2 cleavage were also studied. It turned out that a two-step pathway, where H2 cleavage takes place on the Ni-SIa redox state of the enzyme, is characterized by very low reaction barriers and favorable reaction energies. More importantly, the seesaw coordination geometry of Ni was found to be a key feature for facile H2 cleavage. The discovery of the crucial influence of the Ni coordination geometry on H2 binding and activation in the active site of [NiFe]-hydrogenases could be exploited in the design of novel biomimetic synthetic catalysts.

Directed modification of L-LcLDH1, an L-lactate dehydrogenase from Lactobacillus casei, to improve its specific activity and catalytic efficiency towards phenylpyruvic acid.

Science.gov (United States)

Li, Jian-Fang; Li, Xue-Qing; Liu, Yan; Yuan, Feng-Jiao; Zhang, Ting; Wu, Min-Chen; Zhang, Ji-Ru

2018-05-22

To improve the specific activity and catalytic efficiency of L-LcLDH1, an NADH-dependent allosteric L-lactate dehydrogenase from L. casei, towards phenylpyruvic acid (PPA), its directed modification was conducted based on the semi-rational design. The three variant genes, Lcldh1 Q88R , Lcldh1 I229A and Lcldh1 T235G , were constructed by whole-plasmid PCR as designed theoretically, and expressed in E. coli BL21(DE3), respectively. The purified mutant, L-LcLDH1 Q88R or L-LcLDH1 I229A , displayed the specific activity of 451.5 or 512.4 U/mg towards PPA, by which the asymmetric reduction of PPA afforded L-phenyllactic acid (PLA) with an enantiomeric excess (ee p ) more than 99%. Their catalytic efficiencies (k cat /K m ) without D-fructose-1,6-diphosphate (D-FDP) were 4.8- and 5.2-fold that of L-LcLDH1. Additionally, the k cat /K m values of L-LcLDH1 Q88R and L-LcLDH1 I229A with D-FDP were 168.4- and 8.5-fold higher than those of the same enzymes without D-FDP, respectively. The analysis of catalytic mechanisms by molecular docking (MD) simulation indicated that substituting I229 in L-LcLDH1 with Ala enlarges the space of substrate-binding pocket, and that the replacement of Q88 with Arg makes the inlet of pocket larger than that of L-LcLDH1. Copyright © 2018 Elsevier B.V. All rights reserved.

Microcomputer Assisted Interpretative Reporting of Sequential Creatine Kinase (CK) and Lactate Dehydrogenase (LDH) Isoenzyme Determination

Science.gov (United States)

Talamo, Thomas S.; Losos, Frank J.; Mercer, Donald W.

1984-01-01

We have developed a microcomputer based system for interpretative reporting of creatine kinase (CK) and lactate dehydrogenase (LDH) isoenzyme studies. Patient demographic data and test results (total CK, CK-MB, LD-1, and LD-2) are entered manually through the keyboard. The test results are compared with normal range values and an interpretative report is generated. This report consists of all pertinent demographic information with a graphic display of up to 12 previous CK and LDH isoenzyme determinations. Diagnostic interpretative statements are printed beneath the graphic display following analysis of previously entered test results. The combination of graphic data display and interpretations based on analysis of up to 12 previous specimens provides useful and accurate information to the cardiologist.

Reduced grain chalkiness and its possible physiological mechanism in transgenic rice overexpressing l-GalLDH

Directory of Open Access Journals (Sweden)

Le Yu

2015-04-01

Full Text Available Chalkiness is one of the key factors determining rice quality and price. Ascorbic acid (Asc is a major plant antioxidant that performs many functions in plants. l-Galactono-1,4-lactone dehydrogenase (l-GalLDH, EC1.3.2.3 is an enzyme that catalyzes the final step of Asc biosynthesis in plants. Here we show that the l-GalLDH-overexpressing transgenic rice, GO-2, which has constitutively higher leaf Asc content than wild-type (WT plants, exhibits significantly reduced grain chalkiness. Higher foliar ascorbate/dehydroascorbate (Asc/DHA ratios at 40, 60, 80, and 100 days of plant age were observed in GO-2. Further investigation showed that the enhanced level of Asc resulted in a significantly higher ribulose-1,5-bisphosphate (RuBP carboxylase/oxygenase (Rubisco protein level in GO-2 at 80 days. In addition, levels of abscisic acid (ABA and jasmonic acid (JA were lower in GO-2 at 60, 80, and 100 days. The results we present here indicate that the enhanced level of Asc is likely responsible for changing redox homeostasis in key developmental stages associated with grain filling and alters grain chalkiness in the l-GalLDH-overexpressing transgenic by maintaining photosynthetic function and affecting phytohormones associated with grain filling.

Serum levels of LDH, CEA, and CA19-9 have prognostic roles on survival in patients with metastatic pancreatic cancer receiving gemcitabine-based chemotherapy.

Science.gov (United States)

Tas, Faruk; Karabulut, Senem; Ciftci, Rumeysa; Sen, Fatma; Sakar, Burak; Disci, Rian; Duranyildiz, Derya

2014-06-01

Serum LDH, CEA, and CA19-9 levels are important tumor markers in pancreatic cancer. The purpose of this study was to evaluate the clinical significance of serum LDH, CEA, and CA19-9 levels in metastatic pancreatic cancer (MPC) receiving gemcitabine-based chemotherapy. In this retrospective study, we analyzed the outcome of 196 MPC patients who are treated with gemcitabine-based chemotherapy in our clinic. Positivity rates of serum LDH, CEA, and CA19-9 were 22, 40, and 83 %, respectively. Likewise, the rates of very high serum levels of tumor markers were correlated with these positivity rates (9 % for LDH, 30 % for CEA, and 55 % for CA19-9). The serum LDH levels were significantly higher in older patients (p = 0.05) and also in the patients with large tumors (p = 0.05), hepatic metastasis (p = 0.01), hypoalbuminemia (p = 0.01), and unresponsive to chemotherapy (p = 0.04). However, no correlation was found between both serum CEA and CA19-9 levels and possible prognostic factors (p > 0.05). The significant relationships were found between the serum levels of CEA and CA19-9 (r s = 0.24, p = 0.004), and serum LDH and CEA (r(s) = 0.193, p = 0.02). But, there was no correlation between serum LDH and CA19-9 levels (p = 0.39). One-year overall survival rate was 12.8 % (95 % CI 8-18). Increased serum levels of all the tumor markers significantly had adverse affect on survival (p = 0.001 for LDH, p = 0.002 for CEA, and p = 0.007 for CA19-9). However, no difference was observed in between high levels and very high levels of serum markers for all tumor markers (p > 0.05). Patients with normal serum levels of all three tumor markers had better outcome than others (p = 0.002) and those with normal serum LDH and CEA levels (whatever CA19-9) levels had associated with better survival compared with other possible alternatives (p CEA, and CA19-9 had significant affect on survival in MPC patients.

Identification of an Isothiocyanate on the HypEF Complex Suggests a Route for Efficient Cyanyl-Group Channeling during [NiFe]-Hydrogenase Cofactor Generation.

Directory of Open Access Journals (Sweden)

Sven T Stripp

Full Text Available [NiFe]-hydrogenases catalyze uptake and evolution of H2 in a wide range of microorganisms. The enzyme is characterized by an inorganic nickel/ iron cofactor, the latter of which carries carbon monoxide and cyanide ligands. In vivo generation of these ligands requires a number of auxiliary proteins, the so-called Hyp family. Initially, HypF binds and activates the precursor metabolite carbamoyl phosphate. HypF catalyzes removal of phosphate and transfers the carbamate group to HypE. In an ATP-dependent condensation reaction, the C-terminal cysteinyl residue of HypE is modified to what has been interpreted as thiocyanate. This group is the direct precursor of the cyanide ligands of the [NiFe]-hydrogenase active site cofactor. We present a FT-IR analysis of HypE and HypF as isolated from E. coli. We follow the HypF-catalyzed cyanation of HypE in vitro and screen for the influence of carbamoyl phosphate and ATP. To elucidate on the differences between HypE and the HypEF complex, spectro-electrochemistry was used to map the vibrational Stark effect of naturally cyanated HypE. The IR signature of HypE could ultimately be assigned to isothiocyanate (-N=C=S rather than thiocyanate (-S-C≡N. This has important implications for cyanyl-group channeling during [NiFe]-hydrogenase cofactor generation.

A Ni-P@NiCo LDH core-shell nanorod-decorated nickel foam with enhanced areal specific capacitance for high-performance supercapacitors.

Science.gov (United States)

Xing, Jiale; Du, Jing; Zhang, Xuan; Shao, Yubo; Zhang, Ting; Xu, Cailing

2017-08-14

Recently, transition metal-based nanomaterials have played a key role in the applications of supercapacitors. In this study, nickel phosphide (Ni-P) was simply combined with NiCo LDH via facile phosphorization of Ni foam and subsequent electrodeposition to form core-shell nanorod arrays on the Ni foam; the Ni-P@NiCo LDH was then directly used for a pseudocapacitive electrode. Owing to the splendid synergistic effect between Ni-P and NiCo LDH nanosheets as well as the hierarchical structure of 1D nanorods, 2D nanosheets, and 3D Ni foam, the hybrid electrode exhibited significantly enhanced electrochemical performances. The Ni-P@NiCo LDH electrode showed a high specific capacitance of 12.9 F cm -2 at 5 mA cm -2 (3470.5 F g -1 at a current density of 1.3 A g -1 ) that remained as high as 6.4 F cm -2 at a high current density of 100 mA cm -2 (1700 F g -1 at 27 A g -1 ) and excellent cycling stability (96% capacity retention after 10 000 cycles at 40 mA cm -2 ). Furthermore, the asymmetric supercapacitors (ASCs) were assembled using Ni-P@NiCo LDH as a positive electrode and activated carbon (AC) as a negative electrode. The obtained ASCs delivered remarkable energy density and power density as well as good cycling performance. The enhanced electrochemical activities open a new avenue for the development of supercapacitors.

Electron transfer activation of a second water channel for proton transport in [FeFe]-hydrogenase

Energy Technology Data Exchange (ETDEWEB)

Sode, Olaseni; Voth, Gregory A., E-mail: gavoth@uchicago.edu [Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, Computation Institute, The University of Chicago, Chicago, Illinois 60637, USA and Computing, Environment and Life Sciences, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2014-12-14

Hydrogenase enzymes are important because they can reversibly catalyze the production of molecular hydrogen. Proton transport mechanisms have been previously studied in residue pathways that lead to the active site of the enzyme via residues Cys299 and Ser319. The importance of this pathway and these residues has been previously exhibited through site-specific mutations, which were shown to interrupt the enzyme activity. It has been shown recently that a separate water channel (WC2) is coupled with electron transport to the active site of the [FeFe]-hydrogenase. The water-mediated proton transport mechanisms of the enzyme in different electronic states have been studied using the multistate empirical valence bond reactive molecular dynamics method, in order to understand any role WC2 may have in facilitating the residue pathway in bringing an additional proton to the enzyme active site. In a single electronic state A{sup 2−}, a water wire was formed through which protons can be transported with a low free energy barrier. The remaining electronic states were shown, however, to be highly unfavorable to proton transport in WC2. A double amino acid substitution is predicted to obstruct proton transport in electronic state A{sup 2-} by closing a cavity that could otherwise fill with water near the proximal Fe of the active site.

Electron transfer activation of a second water channel for proton transport in [FeFe]-hydrogenase

International Nuclear Information System (INIS)

Sode, Olaseni; Voth, Gregory A.

2014-01-01

Hydrogenase enzymes are important because they can reversibly catalyze the production of molecular hydrogen. Proton transport mechanisms have been previously studied in residue pathways that lead to the active site of the enzyme via residues Cys299 and Ser319. The importance of this pathway and these residues has been previously exhibited through site-specific mutations, which were shown to interrupt the enzyme activity. It has been shown recently that a separate water channel (WC2) is coupled with electron transport to the active site of the [FeFe]-hydrogenase. The water-mediated proton transport mechanisms of the enzyme in different electronic states have been studied using the multistate empirical valence bond reactive molecular dynamics method, in order to understand any role WC2 may have in facilitating the residue pathway in bringing an additional proton to the enzyme active site. In a single electronic state A 2− , a water wire was formed through which protons can be transported with a low free energy barrier. The remaining electronic states were shown, however, to be highly unfavorable to proton transport in WC2. A double amino acid substitution is predicted to obstruct proton transport in electronic state A 2- by closing a cavity that could otherwise fill with water near the proximal Fe of the active site

Hydrogen production and metabolic flux analysis of metabolically engineered Escherichia coli strains

Energy Technology Data Exchange (ETDEWEB)

Kim, Seohyoung; Seol, Eunhee; Park, Sunghoon [Department of Chemical and Biochemical Engineering, Pusan National University, Busan 609-735 (Korea); Oh, You-Kwan [Bioenergy Research Center, Korea Institute of Energy Research, Daejeon 305-543 (Korea); Wang, G.Y. [Department of Oceanography, University of Hawaii at Manoa Honolulu, HI 96822 (United States)

2009-09-15

Escherichia coli can produce H{sub 2} from glucose via formate hydrogen lyase (FHL). In order to improve the H{sub 2} production rate and yield, metabolically engineered E. coli strains, which included pathway alterations in their H{sub 2} production and central carbon metabolism, were developed and characterized by batch experiments and metabolic flux analysis. Deletion of hycA, a negative regulator for FHL, resulted in twofold increase of FHL activity. Deletion of two uptake hydrogenases (1 (hya) and hydrogenase 2 (hyb)) increased H{sub 2} production yield from 1.20 mol/mol glucose to 1.48 mol/mol glucose. Deletion of lactate dehydrogenase (ldhA) and fumarate reductase (frdAB) further improved the H{sub 2} yield; 1.80 mol/mol glucose under high H{sub 2} pressure or 2.11 mol/mol glucose under reduced H{sub 2} pressure. Several batch experiments at varying concentrations of glucose (2.5-10 g/L) and yeast extract (0.3 or 3.0 g/L) were conducted for the strain containing all these genetic alternations, and their carbon and energy balances were analyzed. The metabolic flux analysis revealed that deletion of ldhA and frdAB directed most of the carbons from glucose to the glycolytic pathway leading to H{sub 2} production by FHL, not to the pentose phosphate pathway. (author)

PREPARATION AND VISIBLE LIGHT RESPONSIVE PHOTOCATALYTIC ACTIVITY OF Fe3O4/Ni-Al-Ce LDH/Bi2WO6 COMPOSITES

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Jiaqi Hao

Full Text Available Novel Fe3O4/Ni-Al-Ce LDH/Bi2WO6 composites were prepared through a hydrothermal method and co-precipitation method. The morphologies and structures of the photocatalysts were characterized by XRD, Raman, TEM, UV-vis-DRS, BET surface area and VSM techniques. The photocatalytic performances of the photocatalysts were investigated by the decolorization of methyl orange (MO under visible-light irradiation. The results showed that the Fe3O4/Ni-Al-Ce LDH/Bi2WO6 composites exhibited greater photocatalytic activities compared to pure Bi2WO6 and the Ni-Al-Ce LDH; the decolorization rate of MO was 87% within 60 min under visible-light irradiation. The decolorization efficiency of the composite material remained at 71% after 4 recycling runs, showing improved stability. Furthermore, the experimental results also showed that the photocatalytic reactions for the composites followed first-order reaction kinetics. Therefore, the Fe3O4/Ni-Al-Ce LDH/Bi2WO6 composites were photocatalysts with high efficiencies and stabilities for a photocatalytic reaction of an organic pollutant, and this study provides a new, effective method for the development of wastewater treatment.

Hierarchical NiCo-LDH@NiOOH core-shell heterostructure on carbon fiber cloth as battery-like electrode for supercapacitor

Science.gov (United States)

Liang, Haoyan; Lin, Jinghuang; Jia, Henan; Chen, Shulin; Qi, Junlei; Cao, Jian; Lin, Tiesong; Fei, Weidong; Feng, Jicai

2018-02-01

Constructing rational structure and utilizing distinctive components are two important keys to promote the development of high performance supercapacitor. Herein, we adopt a facile two-step method to develop an in-situ heterostructure with NiCo-LDH nanowire as core and NiOOH nanosheets as shell on carbon fiber cloth. The resultant NiCo-LDH@NiOOH electrode exhibites a high specific capacitance of about 2622 F g-1 at 1 A g-1 and good cycling stability (88.5% remain after 10000 cycles). This reinforced electrochemical performance is benefit from the distinct core-shell structure, and takes advantage of the synergetic effect to supply more electrochemical active spots and pathways to accelerate electron and ion transport. Furthermore, the fabricated asymmetric supercapacitor of optimized NiCo-LDH@NiOOH//AC device displays a high energy density of 51.7 Wh kg-1 while the power density is 599 W kg-1 and presents a satisfying cycling performance.

Construction and use of a Cupriavidus necator H16 soluble hydrogenase promoter (PSH fusion to gfp (green fluorescent protein

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Bat-Erdene Jugder

2016-07-01

Full Text Available Hydrogenases are metalloenzymes that reversibly catalyse the oxidation or production of molecular hydrogen (H2. Amongst a number of promising candidates for application in the oxidation of H2 is a soluble [Ni–Fe] uptake hydrogenase (SH produced by Cupriavidus necator H16. In the present study, molecular characterisation of the SH operon, responsible for functional SH synthesis, was investigated by developing a green fluorescent protein (GFP reporter system to characterise PSH promoter activity using several gene cloning approaches. A PSH promoter-gfp fusion was successfully constructed and inducible GFP expression driven by the PSH promoter under de-repressing conditions in heterotrophic growth media was demonstrated in the recombinant C. necator H16 cells. Here we report the first successful fluorescent reporter system to study PSH promoter activity in C. necator H16. The fusion construct allowed for the design of a simple screening assay to evaluate PSH activity. Furthermore, the constructed reporter system can serve as a model to develop a rapid fluorescent based reporter for subsequent small-scale process optimisation experiments for SH expression.

Inactivation of uptake hydrogenase leads to enhanced and sustained hydrogen production with high nitrogenase activity under high light exposure in the cyanobacterium Anabaena siamensis TISTR 8012

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Khetkorn Wanthanee

2012-10-01

Full Text Available Abstract Background Biohydrogen from cyanobacteria has attracted public interest due to its potential as a renewable energy carrier produced from solar energy and water. Anabaena siamensis TISTR 8012, a novel strain isolated from rice paddy field in Thailand, has been identified as a promising cyanobacterial strain for use as a high-yield hydrogen producer attributed to the activities of two enzymes, nitrogenase and bidirectional hydrogenase. One main obstacle for high hydrogen production by A. siamensis is a light-driven hydrogen consumption catalyzed by the uptake hydrogenase. To overcome this and in order to enhance the potential for nitrogenase based hydrogen production, we engineered a hydrogen uptake deficient strain by interrupting hupS encoding the small subunit of the uptake hydrogenase. Results An engineered strain lacking a functional uptake hydrogenase (∆hupS produced about 4-folds more hydrogen than the wild type strain. Moreover, the ∆hupS strain showed long term, sustained hydrogen production under light exposure with 2–3 folds higher nitrogenase activity compared to the wild type. In addition, HupS inactivation had no major effects on cell growth and heterocyst differentiation. Gene expression analysis using RT-PCR indicates that electrons and ATP molecules required for hydrogen production in the ∆hupS strain may be obtained from the electron transport chain associated with the photosynthetic oxidation of water in the vegetative cells. The ∆hupS strain was found to compete well with the wild type up to 50 h in a mixed culture, thereafter the wild type started to grow on the relative expense of the ∆hupS strain. Conclusions Inactivation of hupS is an effective strategy for improving biohydrogen production, in rates and specifically in total yield, in nitrogen-fixing cultures of the cyanobacterium Anabaena siamensis TISTR 8012.

High glutamate attenuates S100B and LDH outputs from rat cortical slices enhanced by either oxygen-glucose deprivation or menadione.

Science.gov (United States)

Demircan, Celaleddin; Gül, Zülfiye; Büyükuysal, R Levent

2014-07-01

One hour incubation of rat cortical slices in a medium without oxygen and glucose (oxygen-glucose deprivation, OGD) increased S100B release to 6.53 ± 0.3 ng/ml/mg protein from its control value of 3.61 ± 0.2 ng/ml/mg protein. When these slices were then transferred to a medium containing oxygen and glucose (reoxygenation, REO), S100B release rose to 344 % of its control value. REO also caused 192 % increase in lactate dehydrogenase (LDH) leakage. Glutamate added at millimolar concentration into the medium decreased OGD or REO-induced S100B release and REO-induced LDH leakage. Alpha-ketoglutarate, a metabolic product of glutamate, was found to be as effective as glutamate in decreasing the S100B and LDH outputs. Similarly lactate, 2-ketobutyrate and ethyl pyruvate, a lipophilic derivative of pyruvate, also exerted a glutamate-like effect on S100B and LDH outputs. Preincubation with menadione, which produces H2O2 intracellularly, significantly increased S100B and LDH levels in normoxic medium. All drugs tested in the present study, with the exception of pyruvate, showed a complete protection against menadione preincubation. Additionally, each OGD-REO, menadione or H2O2-induced mitochondrial energy impairments determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining and OGD-REO or menadione-induced increases in reactive oxygen substances (ROS) determined by 2,7-dichlorofluorescin diacetate (DCFH-DA) were also recovered by glutamate. Interestingly, H2O2-induced increase in fluorescence intensity derived from DCFH-DA in a slice-free physiological medium was attenuated significantly by glutamate and alpha-keto acids. All these drug actions support the conclusion that high glutamate, such as alpha-ketoglutarate and other keto acids, protects the slices against OGD- and REO-induced S100B and LDH outputs probably by scavenging ROS in addition to its energy substrate metabolite property.

Improved growth rate in Clostridium thermocellum hydrogenase mutant via perturbed sulfur metabolism.

Science.gov (United States)

Biswas, Ranjita; Wilson, Charlotte M; Giannone, Richard J; Klingeman, Dawn M; Rydzak, Thomas; Shah, Manesh B; Hettich, Robert L; Brown, Steven D; Guss, Adam M

2017-01-01

Metabolic engineering is a commonly used approach to develop organisms for an industrial function, but engineering aimed at improving one phenotype can negatively impact other phenotypes. This lack of robustness can prove problematic. Cellulolytic bacterium Clostridium thermocellum is able to rapidly ferment cellulose to ethanol and other products. Recently, genes involved in H 2 production, including the hydrogenase maturase hydG and NiFe hydrogenase ech , were deleted from the chromosome of C. thermocellum . While ethanol yield increased, the growth rate of Δ hydG decreased substantially compared to wild type. Addition of 5 mM acetate to the growth medium improved the growth rate in C. thermocellum ∆hydG , whereas wild type remained unaffected. Transcriptomic analysis of the wild type showed essentially no response to the addition of acetate. However, in C. thermocellum ΔhydG , 204 and 56 genes were significantly differentially regulated relative to wild type in the absence and presence of acetate, respectively. Genes, Clo1313_0108-0125, which are predicted to encode a sulfate transport system and sulfate assimilatory pathway, were drastically upregulated in C. thermocellum ΔhydG in the presence of added acetate. A similar pattern was seen with proteomics. Further physiological characterization demonstrated an increase in sulfide synthesis and elimination of cysteine consumption in C. thermocellum ΔhydG . Clostridium thermocellum ΔhydGΔech had a higher growth rate than ΔhydG in the absence of added acetate, and a similar but less pronounced transcriptional and physiological effect was seen in this strain upon addition of acetate. Sulfur metabolism is perturbed in C. thermocellum ΔhydG strains, likely to increase flux through sulfate reduction to act either as an electron sink to balance redox reactions or to offset an unknown deficiency in sulfur assimilation.

Minimal Influence of [NiFe] Hydrogenase on Hydrogen Isotope Fractionation in H2-Oxidizing Cupriavidus necator

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Brian J. Campbell

2017-10-01

Full Text Available Fatty acids produced by H2-metabolizing bacteria are sometimes observed to be more D-depleted than those of photoautotrophic organisms, a trait that has been suggested as diagnostic for chemoautotrophic bacteria. The biochemical reasons for such a depletion are not known, but are often assumed to involve the strong D-depletion of H2. Here, we cultivated the bacterium Cupriavidus necator H16 (formerly Ralstonia eutropha H16 under aerobic, H2-consuming, chemoautotrophic conditions and measured the isotopic compositions of its fatty acids. In parallel with the wild type, two mutants of this strain, each lacking one of two key hydrogenase enzymes, were also grown and measured. In all three strains, fractionations between fatty acids and water ranged from -173‰ to -235‰, and averaged -217‰, -196‰, and -226‰, respectively, for the wild type, SH- mutant, and MBH- mutant. There was a modest increase in δD as a result of loss of the soluble hydrogenase enzyme. Fractionation curves for all three strains were constructed by growing parallel cultures in waters with δDwater values of approximately -25‰, 520‰, and 1100‰. These curves indicate that at least 90% of the hydrogen in fatty acids is derived from water, not H2. Published details of the biochemistry of the soluble and membrane-bound hydrogenases confirm that these enzymes transfer electrons rather than intact hydride (H- ions, providing no direct mechanism to connect the isotopic composition of H2 to that of lipids. Multiple lines of evidence thus agree that in this organism, and presumably others like it, environmental H2 plays little or no direct role in controlling lipid δD values. The observed fractionations must instead result from isotope effects in the reduction of NAD(PH by reductases with flavin prosthetic groups, which transfer two electrons and acquire H+ (or D+ from solution. Parallels to NADPH reduction in photosynthesis may explain why D/H fractionations in C. necator

LDH and G-6PDH activities in the ovaries of adult female Wistar rats ...

African Journals Online (AJOL)

The present study was designed to evaluate the effects of aqueous extracts of neem (Azadirachta Indica) leaves (which have been documented for its antifertility effect on experimental animals) on glucose-6-phosphate dehydrogenase (G-6PDH) and lactate dehydrogenase (LDH) levels in the ovaries of adult female wistar ...

Determination of lactate dehydrogenase (LDH and Bcr-Abl transcript in the follow-up of patients with chronic myeloid leukemia - doi: 10.4025/actascihealthsci.v32i2.6408 Determination of lactate dehydrogenase (LDH and Bcr-Abl transcript in the follow-up of patients with chronic myeloid leukemia - doi: 10.4025/actascihealthsci.v32i2.6408

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Thiago Cezar Fujita

2010-09-01

Full Text Available Chronic myeloid leukemia (CML is a malignant myeloproliferative disorder that originates from a pluripotent stem cell characterized by abnormal release of the expanded, malignant stem cell clone from the bone marrow into the bloodstream. The vast majority of patients with CML present Bcr-Abl transcripts. Lactate dehydrogenase (LDH is considered a biochemical marker common for tumor growth, anaerobic glycolysis and has been considered a poor prognostic factor for acute myeloid leukemia. Therefore, this study aimed to evaluate the concentration of LDH in plasma and the detection of the Bcr-Abl transcripts in patients with CML and healthy donors. We analyzed 22 patients demonstrably diagnosed with CML and 56 healthy donors. LDH concentration in plasma was higher in patients with CML. All patients with CML in this study were under treatment, but even so four patients had the Bcr-Abl (b3a2 transcript in peripheral blood. Two out of the four patients with b3a2 showed higher LDH (486 U L-1 and 589 U L-1. Thus, although the study was conducted with small numbers of samples, it is possible to suggest therapy alteration for two patients who presented transcript b3a2 in the peripheral blood samples and whose LDH concentration was high, in order to improve the disease.Chronic myeloid leukemia (CML is a malignant myeloproliferative disorder that originates from a pluripotent stem cell characterized by abnormal release of the expanded, malignant stem cell clone from the bone marrow into the bloodstream. The vast majority of patients with CML present Bcr-Abl transcripts. Lactate dehydrogenase (LDH is considered a biochemical marker common for tumor growth, anaerobic glycolysis and has been considered a poor prognostic factor for acute myeloid leukemia. Therefore, this study aimed to evaluate the concentration of LDH in plasma and the detection of the Bcr-Abl transcripts in patients with CML and healthy donors. We analyzed 22 patients demonstrably diagnosed

Effect of surfactant alkyl chain length on the dispersion, and thermal and dynamic mechanical properties of LDPE/organo-LDH composites

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2011-05-01

Full Text Available Low density polyethylene/layered double hydroxide (LDH composites were prepared via melt compounding using different kinds of organo-LDHs and polyethylene-grafted maleic anhydride as the compatibilizer. The organo-LDHs were successfully prepared by converting a commercial MgAl-carbonate LDH into a MgAl-nitrate LDH, which was later modified by anion exchange with linear and branched sodium alkyl sulfates having different alkyl chain lengths (nc = 6, 12 and 20. It was observed that, depending on the size of the surfactant alkyl chain, different degrees of polymer chain intercalation were achieved, which is a function of the interlayer distance of the organo-LDHs, of the packing level of the alkyl chains, and of the different interaction levels between the surfactant and the polymer chains. In particular, when the number of carbon atoms of the surfactant alkyl chain is larger than 12, the intercalation of polymer chains in the interlayer space and depression of the formation of large aggregates of organo-LDH platelets are favored. A remarkable improvement of the thermal-oxidative degradation was evidenced for all of the composites; whereas only a slight increase of the crystallization temperature and no significant changes of both melting temperature and degree of crystallinity were achieved. By thermodynamic mechanical analysis, it was evidenced that a softening of the matrix is may be due to the plasticizing effect of the surfactant.

Effect of Ultraviolet Aging on Rheology and Chemistry of LDH-Modified Bitumen

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Xing Liu

2015-08-01

Full Text Available Layered double hydroxides (LDHs are an ultravioletlight (UV-resistant material. In this study, two types of LDHs (Mg-Al-LDHs and Zn-Al-LDHs were applied to modify bitumen by melt-blending. The effect of ultraviolet aging on the rheology and chemistry of LDH-modified bitumen was studied by means of dynamic shear rheometer (DSR, thin-layer chromatography with flame ionization detection (TLC-FID, Fourier transform infrared spectroscopy (FTIR, and Ultraviolet-Visible (UV-Vis spectrophotometry to reveal the mechanisms of action for LDHs and bitumen. The results showed that within the UV spectra (220–400 nm, the reflectance of Zn-Al-LDHs was larger than that of Mg-Al-LDHs. These two LDHs have different influences on the performance of bitumen. Mg-Al-LDHs had a more obvious influence on the physical and dynamic rheological properties of bitumen than Zn-Al-LDHs. Zn-Al-LDHs improved the UV-aging resistance of bitumen more. The reason can be that the reflectance of the Zn-Al-LDHs to the UV light is larger than that of the Mg-Al-LDHs. The Zn-Al-LDH-modified bitumen had more potential to improve the UV-aging resistance during the service life of asphalt pavement.

Hydrogen production by Chlamydomonas reinhardtii: an elaborate interplay of electron sources and sinks

International Nuclear Information System (INIS)

Hemschemeier, A; Happe, T.; Fouchard, S; Cournac, L; Peltier, G.

2008-01-01

The unicellular green alga Chlamydomonas reinhardtii possesses a [FeFe]-hydrogenase HydA1 (EC 1.12.7.2), which is coupled to the photosynthetic electron transport chain. Large amounts of H 2 are produced in a light-dependent reaction for several days when C. reinhardtii cells are deprived of sulfur. Under these conditions, the cells drastically change their physiology from aerobic photosynthetic growth to an anaerobic resting state. The understanding of the underlying physiological processes is not only important for getting further insights into the adaptability of photosynthesis, but will help to optimize the biotechnological application of algae as H 2 producers. Two of the still most disputed questions regarding H 2 generation by C. reinhardtii concern the electron source for H 2 evolution and the competition of the hydrogenase with alternative electron sinks. We analyzed the H 2 metabolism of S-depleted C. reinhardtii cultures utilizing a special mass spectrometer setup and investigated the influence of photosystem II (PSII)- or ribulose-bisphosphate-carboxylase/oxygenase (Rubisco)-deficiency. We show that electrons for H 2 -production are provided both by PSII activity and by a non-photochemical plastoquinone reduction pathway, which is dependent on previous PSII activity. In a Rubisco-deficient strain, which produces H 2 also in the presence of sulfur, H 2 generation seems to be the only significant electron sink for PSII activity and rescues this strain at least partially from a light-sensitive phenotype.The latter indicates that the down-regulation of assimilatory pathways in S-deprived C. reinhardtii cells is one of the important prerequisites for a sustained H 2 evolution. (authors)

Oxygen limitation modulates pH regulation of catabolism and hydrogenases, multidrug transporters, and envelope composition in Escherichia coli K-12

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Radmacher Michael D

2006-10-01

Full Text Available Abstract Background In Escherichia coli, pH regulates genes for amino-acid and sugar catabolism, electron transport, oxidative stress, periplasmic and envelope proteins. Many pH-dependent genes are co-regulated by anaerobiosis, but the overall intersection of pH stress and oxygen limitation has not been investigated. Results The pH dependence of gene expression was analyzed in oxygen-limited cultures of E. coli K-12 strain W3110. E. coli K-12 strain W3110 was cultured in closed tubes containing LBK broth buffered at pH 5.7, pH 7.0, and pH 8.5. Affymetrix array hybridization revealed pH-dependent expression of 1,384 genes and 610 intergenic regions. A core group of 251 genes showed pH responses similar to those in a previous study of cultures grown with aeration. The highly acid-induced gene yagU was shown to be required for extreme-acid resistance (survival at pH 2. Acid also up-regulated fimbriae (fimAC, periplasmic chaperones (hdeAB, cyclopropane fatty acid synthase (cfa, and the "constitutive" Na+/H+ antiporter (nhaB. Base up-regulated core genes for maltodextrin transport (lamB, mal, ATP synthase (atp, and DNA repair (recA, mutL. Other genes showed opposite pH responses with or without aeration, for example ETS components (cyo,nuo, sdh and hydrogenases (hya, hyb, hyc, hyf, hyp. A hypF strain lacking all hydrogenase activity showed loss of extreme-acid resistance. Under oxygen limitation only, acid down-regulated ribosome synthesis (rpl,rpm, rps. Acid up-regulated the catabolism of sugar derivatives whose fermentation minimized acid production (gnd, gnt, srl, and also a cluster of 13 genes in the gadA region. Acid up-regulated drug transporters (mdtEF, mdtL, but down-regulated penicillin-binding proteins (dacACD, mreBC. Intergenic regions containing regulatory sRNAs were up-regulated by acid (ryeA, csrB, gadY, rybC. Conclusion pH regulates a core set of genes independently of oxygen, including yagU, fimbriae, periplasmic chaperones, and nha

Seasonal Changes in Serum Testosterone, LDH Concentration and Semen Characteristics in Markhoz Goats

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A. Farshad

2012-02-01

Full Text Available This experiment was conducted to study variations of serum testosterone and seminal characteristics of Markhoz male goats. Blood samples were obtained via jugular vein, and semen was collected by using an artificial vagina from 14 fertile male goats (2–3 years of age, at 15-day intervals starting on 15 July and ending on 30 October 2010 (during breeding and non-breeding season. Semen volume, total sperm (volume×concentration, live sperm (%, abnormal sperm (% and semen pH were significantly superior during the late summer and early autumn (breeding season. Variation of sperm density, motility and progressive motility was not significant during the sampling period. The results presented show that the lowest and highest levels of lactate dehydrogenase in the seminal plasma were recorded in late October (2.82 U/ml and in late August (4.81 U/ml, respectively. Moreover, the study indicated that the serum testosterone concentration was higher during late summer and early autumn (p<0.05 than at any other of sampling period. There were negative correlations between volume and sperm density (−0.135, p<0.05, and positive correlations between volume and percentage live sperm (0.224 and percentage progressive motility (0.194, p<0.01. Sperm density was correlated with live sperm (0.200, p<0.05 and progressive motility (0.202, p<0.01. The correlation between live sperm and progressive motility was 0.554 (p<0.01. Furthermore, the results in this study indicated a significant positive correlation between live sperm and LDH (0.450 and a negative correlation between sperm density and LDH concentration (−0.272 (p<0.01. Significant, but positive correlations were found between sperm motility and LDH (0.542 and testosterone concentration (0.522, respectively (p<0.05. In conclusion, this study demonstrated that the best obtained semen was collected in late summer (during decreasing photoperiod and early autumn (September and October. This also coincides with

Cloning, sequence determination, and expression of the genes encoding the subunits of the nickel-containing 8-hydroxy-5-deazaflavin reducing hydrogenase from Methanobacterium thermoautotrophicum ΔH

International Nuclear Information System (INIS)

Alex, L.A.; Reeve, J.N.; Orme-Johnson, W.H.; Walsh, C.T.

1990-01-01

The genes frhA (1,217 bp), frhB (845 bp), and frhG (710 bp) encoding the three known subunits, α, β, and γ, of the 8-hydroxy-5-deazaflavin (F 420 ) reducing hydrogenase (FRH) from the thermophilic methanogen Methanobacterium thermoautotrophicum ΔH have been cloned, sequenced, and shown to be tightly linked, indicative of a single transcriptional unit. The DNA sequence contains a fourth open reading frame, designated frhD (476 bp), encoding a polypeptide (δ) that does not copurify with the active enzyme. Expression of the frh gene cluster in Escherichia coli shows that four polypeptides are synthesized. When analyzed by SDS-PAGE, the proteins migrate with mobilities consistent with their calculated molecular weights. In order to understand the mechanism of H 2 oxidation by this enzyme, localization of redox cofactors (Ni, Fe/S, FAD) to specific subunits and information on their structure is needed. This has been hindered due to the refractory nature of the enzyme to denaturation methods needed in order to obtain individual subunits with cofactors intact. In this paper they discuss the possible localization of the redox cofactors as implicated from the DNA-derived protein sequences of the subunits. The amino acid sequences of the subunits of the FRH are compared with those of other Ni-containing hydrogenases, including the methyl viologen reducing hydrogenase (MVH) of M. thermoautotrophicum ΔH

From nicotinate-containing layered double hydroxides (LDHs) to NAD coenzyme-LDH nanocomposites - Syntheses and structural characterization by various spectroscopic methods

Science.gov (United States)

Muráth, Szabolcs; Dudás, Csilla; Kukovecz, Ákos; Kónya, Zoltán; Sipos, Pál; Pálinkó, István

2017-07-01

The syntheses of nicotinate anion- and NAD coenzyme-layered double hydroxide (LDH) composites were performed with the aim of having the organic component among the layers. In-house prepared CaAl-LDHs were the host materials. Intercalation was attempted by direct ion exchange or by the dehydration-rehydration method applying aqueous solvent mixtures (containing ethanol, propanol, acetone, N,N-dimethylformamide). For structural characterization, beside X-ray diffractometry, X-ray photoelectron and IR spectroscopies, transmission and scanning electron microscopies as well as energy-dispersive X-ray analysis were used. Molecular modelling served for the visualization of the arrangements of the intercalated ions among the layers of the LDH samples. Although not all the intercalation methods and solvent mixtures led to intercalated composite materials, successful ones could be identified. The combination of spectroscopic methods helped in proposing sensible spatial arrangements for the intercalated anions. The NAD-CaAl-LDH composite proved to be an active catalyst in the oxidation of hydroquinone to 1,4-bezoquinoe in the presence of H2O2.

Modelling the active site of NiFe hydrogenases: new catalysts for the electro-production of H2 and mechanistic studies

International Nuclear Information System (INIS)

Canaguier, S.

2009-01-01

NiFe hydrogenases are unique metalloenzymes that catalyze H + /H 2 interconversion with remarkable efficiency close to the thermodynamic potential. Their active site consists of a hetero-bimetallic complex containing a nickel ion in a sulphur-rich environment connected by two thiolate bridges to an organometallic cyano-carbonyl iron moiety. In order to improve the understanding of the enzymatic mechanism and to obtain new base-metal electrocatalysts for H 2 production, we synthesized a series of bio-inspired low molecular weight model complexes with the butterfly structure Ni(μ-S 2 )M (M= Ru, Mn and Fe). All these compounds displayed a catalytic activity of hydrogen production. Modulating the electronic and steric properties of the ruthenium center allowed optimizing the catalytic performances of these compounds in terms of stability, catalytic rate and overpotential. Mechanistic studies of the catalytic cycle of the Ni-Ru complexes have also been carried out. They allowed us to suggest a bio-relevant bridging hydride as the catalytic intermediate. Finally, we synthesized one of the first Ni-Fe complexes that is both a structural and a functional model of NiFe hydrogenase. (author) [fr

Deposition of LDH on plasma treated polylactic acid to reduce water permeability

KAUST Repository

Bugatti, Valeria

2013-04-01

A simple and scalable deposition process was developed to prepare polylactic acid (PLA) coatings with enhanced water barrier properties for food packaging applications. This method based on electrostatic interactions between the positively charged layers of layered double hydroxides (LDHs) modified with ionic liquids (ILs) and the negatively charged plasma treated polylactic acid leads to homogeneous, stable, and highly durable coatings. Deposition of the LDH coatings increases the surface hydrophobicity of the neat PLA, which results to a decrease in water permeability by about 35%. © 2013 Elsevier Inc.

Optical and UV-Aging Properties of LDH-Modified Bitumen

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Xing Liu

2015-07-01

Full Text Available Layered double hydroxides (LDHs are an ultraviolet-light (UV resistant material. In this study, LDHs were used to modify bitumen. The optical and UV aging properties of LDHs modified bitumen were investigated. Firstly, the thin films of bitumen, with and without LDHs, were prepared. By using the UV-Vis spectrophotometer, absorbance, reflectance, and transmittance of bituminous thin film were evaluated. The morphology of LDHs-modified bitumen was observed by using fluorescence microscopy (FM. Finally, the aging resistance of LDH-modified bitumen was investigated by using the UV-aging oven. Results indicated that the LDHs, especially with 5 wt % in the bitumen, can effectively absorb and reflect the UV light and improve the UV-aging resistance of bitumen. This implied that the addition of LDHs into bitumen had the potential to prolong the service life of asphalt pavement.

Partial nucleotide sequences, and routine typing by polymerase chain reaction-restriction fragment length polymorphism, of the brown trout (Salmo trutta) lactate dehydrogenase, LDH-C1*90 and *100 alleles.

Science.gov (United States)

McMeel, O M; Hoey, E M; Ferguson, A

2001-01-01

The cDNA nucleotide sequences of the lactate dehydrogenase alleles LDH-C1*90 and *100 of brown trout (Salmo trutta) were found to differ at position 308 where an A is present in the *100 allele but a G is present in the *90 allele. This base substitution results in an amino acid change from aspartic acid at position 82 in the LDH-C1 100 allozyme to a glycine in the 90 allozyme. Since aspartic acid has a net negative charge whilst glycine is uncharged, this is consistent with the electrophoretic observation that the LDH-C1 100 allozyme has a more anodal mobility relative to the LDH-C1 90 allozyme. Based on alignment of the cDNA sequence with the mouse genomic sequence, a local primer set was designed, incorporating the variable position, and was found to give very good amplification with brown trout genomic DNA. Sequencing of this fragment confirmed the difference in both homozygous and heterozygous individuals. Digestion of the polymerase chain reaction products with BslI, a restriction enzyme specific for the site difference, gave one, two and three fragments for the two homozygotes and the heterozygote, respectively, following electrophoretic separation. This provides a DNA-based means of routine screening of the highly informative LDH-C1* polymorphism in brown trout population genetic studies. Primer sets presented could be used to sequence cDNA of other LDH* genes of brown trout and other species.

Ir4+-Doped NiFe LDH to expedite hydrogen evolution kinetics as a Pt-like electrocatalyst for water splitting.

Science.gov (United States)

Chen, Qian-Qian; Hou, Chun-Chao; Wang, Chuan-Jun; Yang, Xiao; Shi, Rui; Chen, Yong

2018-06-06

NiFe-layered double hydroxide (NiFe LDH) is a state-of-the-art oxygen evolution reaction (OER) electrocatalyst, yet it suffers from rather poor catalytic activity for the hydrogen evolution reaction (HER) due to its extremely sluggish water dissociation kinetics, severely restricting its application in overall water splitting. Herein, we report a novel strategy to expedite the HER kinetics of NiFe LDH by an Ir4+-doping strategy to accelerate the water dissociation process (Volmer step), and thus this catalyst exhibits superior and robust catalytic activity for finally oriented overall water splitting in 1 M KOH requiring only a low initial voltage of 1.41 V delivering at 20 mA cm-2 for more than 50 h.

Expressão do Mg+2, CK, AST e LDH em equinos finalistas de provas de enduro Endurance horses finalists: expression of Mg+2, CK, AST and LDH in horse finalists of endurance race

Directory of Open Access Journals (Sweden)

Juliana V.F. Sales

2013-01-01

Full Text Available Nos últimos anos, o equino atleta vem sendo cada vez mais requerido. Dessa forma, as exigências por alto desempenho têm fomentado o interesse pelo estudo das afecções relacionadas com a fisiopatologia de diversas enfermidades dos equinos. A relação entre o íon magnésio e o exercício físico tem recebido atenção significativa visto que este íon está intimamente relacionado ao tecido muscular estriado esquelético. Além disso, dentre as principais estratégias para a detecção e acompanhamento clínico de lesões musculares, destacam-se a avaliação das atividades das enzimas creatino quinase (CK, lactato desidrogenase (LDH e aspartato aminotransferase (AST. A busca pelo estabelecimento de parâmetros que se relacionam entre si é um fator determinante na compreensão de alterações fisiológicas encontradas diante do esforço em equinos atletas. Desta forma, o presente trabalho teve como objetivo determinar como as concentrações sanguíneas do íon magnésio e as atividades enzimáticas das enzimas CK, LDH e AST comportaram-se em equinos Puro Sangue Árabe finalistas de provas de enduro de 90km e relacionar as possíveis alterações com o tipo de esforço físico desempenhado pelos animais. Foram avaliadas a atividade enzimática das enzimas CK, LDH, AST e a concentração do íon magnésio no exercício em relação ao repouso de 14 equinos clinicamente hígidos da raça Puro Sangue Árabe, sendo 9 machos e 5 fêmeas, com idades variando entre 6 a 12 anos, submetidos a treinamento para enduro e participantes de provas de 90 km. Pode-se observar que as variáveis acima mencionadas sofreram aumento com diferença estatística em relação ao repouso. O exercício físico de enduro determinou a ocorrência de alterações nas atividades enzimáticas das enzimas CK (p≤0,001, LDH (p=0,0001, AST (p=0,0007 e na concentração do íon magnésio (p=0,0004, no exercício em relação ao repouso (p≤0,05. Fato que determinou altera

Multiscale Modeling of the Active Site of [Fe] Hydrogenase: The H2 Binding Site in Open and Closed Protein Conformations

DEFF Research Database (Denmark)

Hedegård, Erik D.; Kongsted, Jacob; Ryde, Ulf

2015-01-01

A series of QM/MM optimizations of the full protein of [Fe] hydrogenase were performed. The FeGP cofactor has been optimized in the water-bound resting state (1), with a side-on bound dihydrogen (2), or as a hydride intermediate (3). For inclusion of H4MPT in the closed structure, advanced multis...... that hydride transfer from 3 has a significantly higher barrier than found in previous studies neglecting the full protein environment....

Comparative Study of Ni-Zn LHS and Mg-Al LDH Adsorbents of Navy Blue and Yellow F3G Dye

Directory of Open Access Journals (Sweden)

Idha Yulia Ikhsani

2016-03-01

Full Text Available Adsorption of disperse dyes from wastewater onto Ni-Zn LHS (layered hydroxide salts and Mg-Al LDH (layered double hydroxides has been compared in this study. Effects of initial pH solution, contact time and initial dye concentration were investigated. The ability of the adsorbent to be reused was also studied. The results showed that acidic condition was favorable for the adsorption of each dyes onto both adsorbent. The adsorption kinetics was studied using pseudo-first-order, pseudo-second-order and Santosa’s kinetics models. The experimental data fits well with the pseudo-second order kinetic model. The equilibrium adsorption data were analyzed using Langmuir and Freundlich isotherm models. The results showed that adsorption of navy blue onto both adsorbent followed Freundlich isotherm adsorption, while yellow F3G followed Langmuir isotherm adsorption. In the application for the adsorption the wastewater containing dyes, Ni-Zn LHS has a better adsorption capacity of 52.33 mg/g than that of Mg-Al LDH that 30.54 mg/g. Calcination of the adsorbent which has already been used increased the adsorption capacity of Mg-Al LDH to 84.75 mg/g, but decreased the adsorption capacity of the Ni-Zn LHS to 42.65 mg/g.

Cysteine as a ligand platform in the biosynthesis of the FeFe hydrogenase H cluster.

Science.gov (United States)

Suess, Daniel L M; Bürstel, Ingmar; De La Paz, Liliana; Kuchenreuther, Jon M; Pham, Cindy C; Cramer, Stephen P; Swartz, James R; Britt, R David

2015-09-15

Hydrogenases catalyze the redox interconversion of protons and H2, an important reaction for a number of metabolic processes and for solar fuel production. In FeFe hydrogenases, catalysis occurs at the H cluster, a metallocofactor comprising a [4Fe-4S]H subcluster coupled to a [2Fe]H subcluster bound by CO, CN(-), and azadithiolate ligands. The [2Fe]H subcluster is assembled by the maturases HydE, HydF, and HydG. HydG is a member of the radical S-adenosyl-L-methionine family of enzymes that transforms Fe and L-tyrosine into an [Fe(CO)2(CN)] synthon that is incorporated into the H cluster. Although it is thought that the site of synthon formation in HydG is the "dangler" Fe of a [5Fe] cluster, many mechanistic aspects of this chemistry remain unresolved including the full ligand set of the synthon, how the dangler Fe initially binds to HydG, and how the synthon is released at the end of the reaction. To address these questions, we herein show that L-cysteine (Cys) binds the auxiliary [4Fe-4S] cluster of HydG and further chelates the dangler Fe. We also demonstrate that a [4Fe-4S]aux[CN] species is generated during HydG catalysis, a process that entails the loss of Cys and the [Fe(CO)2(CN)] fragment; on this basis, we suggest that Cys likely completes the coordination sphere of the synthon. Thus, through spectroscopic analysis of HydG before and after the synthon is formed, we conclude that Cys serves as the ligand platform on which the synthon is built and plays a role in both Fe(2+) binding and synthon release.

Preparation and visible light responsive photocatalytic activity of Fe{sub 3}O{sub 4}/Ni-Al-Ce LDH/Bi{sub 2}WO{sub 6} composites

Energy Technology Data Exchange (ETDEWEB)

Hao, Jiaqi; Qu, Ting; Wang, Qiufeng; Zhao, Zhenbo, E-mail: zhaozhenbo@ccut.edu.cn [School of Chemistry and Life Science, Changchun University of Technology, Changchun, Jilin (China)

2017-09-15

Novel Fe{sub 3}O{sub 4}/Ni-Al-Ce LDH/Bi{sub 2}WO{sub 6} composites were prepared through a hydrothermal method and co-precipitation method. The morphologies and structures of the photocatalysts were characterized by XRD, Raman, TEM, UV-vis-DRS, BET surface area and VSM techniques. The photocatalytic performances of the photocatalysts were investigated by the decolorisation of methyl orange (MO) under visible-light irradiation. The results showed that the Fe{sub 3}O{sub 4}/Ni-Al-Ce LDH/Bi{sub 2}WO{sub 6} composites exhibited greater photocatalytic activities compared to pure Bi{sub 2}WO{sub 6} and the Ni-Al-Ce LDH; the decolorisation rate of MO was 87% within 60 min under visible-light irradiation. The decolorisation efficiency of the composite material remained at 71% after 4 recycling runs, showing improved stability. Furthermore, the experimental results also showed that the photocatalytic reactions for the composites followed first-order reaction kinetics. Therefore, the Fe{sub 3}O{sub 4}/Ni-Al-Ce LDH/Bi{sub 2}WO{sub 6} composites were photocatalysts with high efficiencies and stabilities for a photocatalytic reaction of an organic pollutant, and this study provides a new, effective method for the development of wastewater treatment. (author)

Ni adsorption and Ni-Al LDH precipitation in a sandy aquifer: An experimental and mechanistic modeling study

NARCIS (Netherlands)

Regelink, I.C.; Temminghoff, E.J.M.

2011-01-01

Mining activities and industries have created nickel (Ni) contaminations in many parts of the world. The objective of this study is to increase our understanding of Ni adsorption and Nickel-Aluminium Layered Double Hydroxide (Ni-Al LDH) precipitation to reduce Ni mobility in a sandy soil aquifer. At

Diurnal behaviour of some salivary parameters in patients with diabetes mellitus (flow rate, pH, thiocianat, LDH activity)--note II.

Science.gov (United States)

Ionescu, S; Bădiţă, D; Artino, M; Dragomir, M; Huidovici, E; Niţă, V; Chiţoi, E

1998-01-01

The study was performed on 31 diabetic patients of both sexes, divided in 2 groups: group I--17 patients with insulin-dependent diabetes (IDDM) and group II--14 patients with noninsulin-dependent diabetes (NIDDM) and compared with a control group of 16 non-diabetic subjects. Mixed saliva was sampled without stimulation during 2 periods of the day: 07:30-08:00 before breakfast and 17:30-18:00 before dinner. We determined: salivary flow rate, pH with Merck indicator and, after homogenization, the thiocianat with the FeCl3 method and LDH activity (the Norbert method adapted in our laboratory for saliva). Our study showed the same diurnal changes in flow rate and salivary pH in both diabetic and control groups: minimal values in the morning and maximal ones in the afternoon. In non-smoking diabetic patients the salivary thiocianat had maximal values in the morning and minimal ones in the afternoon; similar behaviour, but less obvious was observed in smoking diabetic patients and in the control group regardless of the smoking habit. LDH activity showed unsignificant diurnal variations in the diabetic patients. In the control group we found a significant decrease of LDH activity in the afternoon. The discussion is about the implication of these salivary parameters in the pathology of oral cavity: gingivitis, periodontitis and caries in diabetic patients.

Chapter Eight - Structural Characterization of Poised States in the Oxygen Sensitive Hydrogenases and Nitrogenases

Energy Technology Data Exchange (ETDEWEB)

King, Paul W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mulder, David W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Artz, Jacob H. [Washington State University; Zadvornyy, Oleg A. [Washington State University; Peters, John W. [Washington State University

2017-08-21

The crystallization of FeS cluster-containing proteins has been challenging due to their oxygen sensitivity, and yet these enzymes are involved in many critical catalytic reactions. The last few years have seen a wealth of innovative experiments designed to elucidate not just structural but mechanistic insights into FeS cluster enzymes. Here, we focus on the crystallization of hydrogenases, which catalyze the reversible reduction of protons to hydrogen, and nitrogenases, which reduce dinitrogen to ammonia. A specific focus is given to the different experimental parameters and strategies that are used to trap distinct enzyme states, specifically, oxidants, reductants, and gas-treatments. Other themes presented here include the recent use of Cryo-EM, and how coupling various spectroscopies to crystallization is opening up new approaches for structural and mechanistic analysis.

Isolation and characterization of the small subunit of the uptake hydrogenase from the cyanobacterium Nostoc punctiforme.

Science.gov (United States)

Raleiras, Patrícia; Kellers, Petra; Lindblad, Peter; Styring, Stenbjörn; Magnuson, Ann

2013-06-21

In nitrogen-fixing cyanobacteria, hydrogen evolution is associated with hydrogenases and nitrogenase, making these enzymes interesting targets for genetic engineering aimed at increased hydrogen production. Nostoc punctiforme ATCC 29133 is a filamentous cyanobacterium that expresses the uptake hydrogenase HupSL in heterocysts under nitrogen-fixing conditions. Little is known about the structural and biophysical properties of HupSL. The small subunit, HupS, has been postulated to contain three iron-sulfur clusters, but the details regarding their nature have been unclear due to unusual cluster binding motifs in the amino acid sequence. We now report the cloning and heterologous expression of Nostoc punctiforme HupS as a fusion protein, f-HupS. We have characterized the anaerobically purified protein by UV-visible and EPR spectroscopies. Our results show that f-HupS contains three iron-sulfur clusters. UV-visible absorption of f-HupS has bands ∼340 and 420 nm, typical for iron-sulfur clusters. The EPR spectrum of the oxidized f-HupS shows a narrow g = 2.023 resonance, characteristic of a low-spin (S = ½) [3Fe-4S] cluster. The reduced f-HupS presents complex EPR spectra with overlapping resonances centered on g = 1.94, g = 1.91, and g = 1.88, typical of low-spin (S = ½) [4Fe-4S] clusters. Analysis of the spectroscopic data allowed us to distinguish between two species attributable to two distinct [4Fe-4S] clusters, in addition to the [3Fe-4S] cluster. This indicates that f-HupS binds [4Fe-4S] clusters despite the presence of unusual coordinating amino acids. Furthermore, our expression and purification of what seems to be an intact HupS protein allows future studies on the significance of ligand nature on redox properties of the iron-sulfur clusters of HupS.

Enhanced photocatalytic hydrogen production from an MCM-41-immobilized photosensitizer-[Fe-Fe] hydrogenase mimic dyad.

Science.gov (United States)

Wang, Wen; Yu, Tianjun; Zeng, Yi; Chen, Jinping; Yang, Guoqiang; Li, Yi

2014-11-01

A covalently linked photosensitizer-catalytic center dyad Ps-Hy, consisting of two bis(2-phenylpyridine)(2,2'-bipyridine)iridium(iii) chromophores (Ps) and a diiron hydrogenase mimic (Hy) was constructed by using click reaction. Ps-Hy was incorporated into K(+)-exchanged molecular sieve MCM-41 to form a composite (Ps-Hy@MCM-41), which has been successfully applied to the photochemical production of hydrogen. The catalytic activity of Ps-Hy@MCM-41 is ∼3-fold higher as compared with that of Ps-Hy in the absence of MCM-41. The incorporation of Ps-Hy into MCM-41 stabilizes the catalyst, and consequently, advances the photocatalysis. The present study provides a potential strategy for improving catalytic efficiency of artificial photosynthesis systems using mesoporous molecular sieves.

Accuracy of PfHRP2 versus Pf-pLDH antigen detection by malaria rapid diagnostic tests in hospitalized children in a seasonal hyperendemic malaria transmission area in Burkina Faso.

Science.gov (United States)

Maltha, Jessica; Guiraud, Issa; Lompo, Palpouguini; Kaboré, Bérenger; Gillet, Philippe; Van Geet, Chris; Tinto, Halidou; Jacobs, Jan

2014-01-13

In most sub-Saharan African countries malaria rapid diagnostic tests (RDTs) are now used for the diagnosis of malaria. Most RDTs used detect Plasmodium falciparum histidine-rich protein-2 (PfHRP2), though P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH)-detecting RDTs may have advantages over PfHRP2-detecting RDTs. Only few data are available on the use of RDTs in severe illness and the present study compared Pf-pLDH to PfHRP2-detection. Hospitalized children aged one month to 14 years presenting with fever or severe illness were included over one year. Venous blood samples were drawn for malaria diagnosis (microscopy and RDT), culture and complete blood count. Leftovers were stored at -80 °C and used for additional RDT analysis and PCR. An RDT targeting both PfHRP2 and Pf-pLDH was performed on all samples for direct comparison of diagnostic accuracy with microscopy as reference method. PCR was performed to explore false-positive RDT results. In 376 of 694 (54.2%) included children, malaria was microscopically confirmed. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value were 100.0, 70.9, 69.4 and 100.0%, respectively for PfHRP2-detection and 98.7, 94.0, 91.6 and 99.1%, respectively for Pf-pLDH-detection. Specificity and PPV were significantly lower for PfHRP2-detection (p <0.001). For both detection antigens, specificity was lowest for children one to five years and in the rainy season. PPV for both antigens was highest in the rainy season, because of higher malaria prevalence. False positive PfHRP2 results were associated with prior anti-malarial treatment and positive PCR results (98/114 (86.0%) samples tested). Among children presenting with severe febrile illness in a seasonal hyperendemic malaria transmission area, the present study observed similar sensitivity but lower specificity and PPV of PfHRP2 compared to Pf-pLDH-detection. Further studies should assess the diagnostic accuracy and safety of an

Carbon monoxide and cyanide as intrinsic ligands to iron in the active site of [NiFe]-hydrogenases. NiFe(CN)2CO, biology's way to activate H2

NARCIS (Netherlands)

Pierik, A.J.; Roseboom, W.; Happe, R.P.; Bagley, K.A.; Albracht, S.P.J.

1999-01-01

Infrared-spectroscopic studies on the [NiFe]-hydrogenase of Chromatium vinosum-enriched in 15N or 13C, as well as chemical analyses, show that this enzyme contains three non-exchangeable, intrinsic, diatomic molecules as ligands to the active site, one carbon monoxide molecule and two cyanide

Electrochemical properties of carbon nanotubes-hydrogenase conjugates Langmuir-Blodgett films

International Nuclear Information System (INIS)

Liu, Ai-Rong; Wakayama, Tatsuki; Nakamura, Chikashi; Miyake, Jun; Zorin, Nikolay A.; Qian, Dong-Jin

2007-01-01

We report the preparation of Langmuir-Blodgett (LB) films composed of oxidized carbon nanotubes (CNTs) and hydrogenase (H 2 ase) conjugates and their electrochemical properties. Both single-walled (SWNTs) and multi-walled CNTs (MWNTs) were used to form mixed monolayers with H 2 ase on the Tris-HCl subphase surfaces. By using the LB method, the CNTs-H 2 ase monolayers were transferred onto CaF 2 and indium tin oxide (ITO) electrode surfaces. The LB film modified electrodes showed a couple of waves centered at around -500 mV (versus Ag/AgCl), which corresponding to the redox reaction of [4Fe-4S] 2+/1+ clusters in the H 2 ase. The current intensity was enhanced after co-assembly with CNTs. Because of the different diameters of CNTs, this current intensity was proportional to the scan rate (υ) for the electrodes modified with the LB films of pure H 2 ase and SWNTs-H 2 ase, but to the root of scan rate (υ 1/2 ) for those modified with the MWNTs-H 2 ase LB film. The products of diffusion coefficient and concentration (D 1/2 C) increased in the order of pure H 2 ase, SWNTs-H 2 ase, and MWNTs-H 2 ase LB films

[Effect of baicalin on ATPase and LDH and its regulatory effect on the AC/cAMP/PKA signaling pathway in rats with attention deficit hyperactivity disorder].

Science.gov (United States)

Zhou, Rong-Yi; Wang, Jiao-Jiao; You, Yue; Sun, Ji-Chao; Song, Yu-Chen; Yuan, Hai-Xia; Han, Xin-Min

2017-05-01

To study the effect of baicalin on synaptosomal adenosine triphosphatase (ATPase) and lactate dehydrogenase (LDH) and its regulatory effect on the adenylate cyclase (AC)/cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling pathway in rats with attention deficit hyperactivity disorder (ADHD). A total of 40 SHR rats were randomly divided into five groups: ADHD model, methylphenidate hydrochloride treatment (0.07 mg/mL), and low-dose (3.33 mg/mL), medium-dose (6.67 mg/mL), and high-dose (10 mg/mL) baicalin treatment (n=8 each). Eight WKY rats were selected as normal control group. Percoll density gradient centrifugation was used to prepare brain synaptosomes and an electron microscope was used to observe their structure. Colorimetry was used to measure the activities of ATPase and LDH in synaptosomes. ELISA was used to measure the content of AC, cAMP, and PKA. Compared with the normal control group, the ADHD model group had a significant reduction in the ATPase activity, a significant increase in the LDH activity, and significant reductions in the content of AC, cAMP, and PKA (PATPase activity (PATPase activity (PATPase activity (PATPase and LDH activities in rats with ADHD. The effect of baicalin is dose-dependent, and high-dose baicalin has a significantly greater effect than methylphenidate hydrochloride. Baicalin exerts its therapeutic effect possibly by upregulating the AC/cAMP/PKA signaling pathway.

Spherical LDH-Ag°-montmorillonite heterocoagulated system with a pH-dependent sol-gel structure for controlled accessibility of AgNPs immobilized on the clay lamellae.

Science.gov (United States)

Deák, Ágota; Janovák, László; Tallósy, Szabolcs Péter; Bitó, Tamás; Sebők, Dániel; Buzás, Norbert; Pálinkó, István; Dékány, Imre

2015-02-17

Aqueous suspensions of spherical ZnMgAl-layered double hydroxides [LDH(sph)] and antibacterial silver nanoparticles (AgNPs) deposited on the lamellae of montmorillonite were used for the synthesis of composites, which behave like coherent gels at low pH (≲4.5) and incoherent sols at higher pH (≳4.5). The composition of the composite was chosen as LDH(sph)/Ag°-montm. = 25:75 wt % in order to ensure a sol-gel transition that can also be characterized by viscometry. This pH-sensitive heterocoagulated system consisting of oppositely charged colloid particles was suitable for the release of antimicrobial AgNPs immobilized on the clay lamellae via a pH-controlled gel-sol transition. The heterocoagulation process was also characterized by surface charge titration measurements. Spherical LDH/Ag°-montmorillonite composite samples were identified by X-ray diffraction (XRD) measurements. The morphological properties of the composites were studied, and the presence of the heterocoagulated structure was confirmed by scanning electron microscopy (SEM). The nanoscale structure of the LDH(sph)-Ag°-montmorillonite composite obtained was also verified by small-angle X-ray scattering (SAXS), and the rheological characteristics were studied at various pH values. The viscosity and yield value of the composite decreased by an order of magnitude upon increasing the pH from 3.0 to 5.5. The sol-gel transition of the composite suspension was reversible in the previously mentioned pH range.

Characteristic LDH isozyme electrophoretic patterns in six flatfish species in the Trondheimsfjord, Norway and their utility for the detection of natural species hybrids

KAUST Repository

He, Song

2014-11-19

Abstract: LDH isozyme electrophoretic patterns among 621 specimens of six different flatfish species collected in the Trondheimsfjord, Norway, were characterized by using the isoelectric focusing in polyacrylamide gel (IFPAG) technique. The LDH locus appears to be a reliable tool for species identification in the Trondheimsfjord flatfishes. Hence, these patterns were used to detect and identify potential hybrids, together with morphological traits. Among all the specimens collected during this study no hybrids were detected. From the actual numbers analysed, the natural hybridization rate between European plaice and European flounder in the Trondheimsfjord can be roughly estimated to be less than 1%. This is substantially lower than corresponding values reported from Baltic and Danish waters.

Characteristic LDH isozyme electrophoretic patterns in six flatfish species in the Trondheimsfjord, Norway and their utility for the detection of natural species hybrids

KAUST Repository

He, Song; Mork, Jarle

2014-01-01

Abstract: LDH isozyme electrophoretic patterns among 621 specimens of six different flatfish species collected in the Trondheimsfjord, Norway, were characterized by using the isoelectric focusing in polyacrylamide gel (IFPAG) technique. The LDH locus appears to be a reliable tool for species identification in the Trondheimsfjord flatfishes. Hence, these patterns were used to detect and identify potential hybrids, together with morphological traits. Among all the specimens collected during this study no hybrids were detected. From the actual numbers analysed, the natural hybridization rate between European plaice and European flounder in the Trondheimsfjord can be roughly estimated to be less than 1%. This is substantially lower than corresponding values reported from Baltic and Danish waters.

Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit S 100 covering

International Nuclear Information System (INIS)

Arco, M. del; Fernandez, A.; Martin, C.; Rives, V.

2010-01-01

Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg 2+ and Al 3+ or Mg 2+ , Al 3+ and Fe 3+ in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 A. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7. - Graphical abstract: LDHs containing Mg, Al, Fe increase fenbufen solubility, release takes place through ionic exchange with phosphate anions from the medium. Spherical solids with homogeneous, smooth surface are formed when using Eudragit S 100, efficiently covering the LDH surface. Display Omitted

Heterobimetallic [NiFe] Complexes Containing Mixed CO/CN- Ligands: Analogs of the Active Site of the [NiFe] Hydrogenases.

Science.gov (United States)

Perotto, Carlo U; Sodipo, Charlene L; Jones, Graham J; Tidey, Jeremiah P; Blake, Alexander J; Lewis, William; Davies, E Stephen; McMaster, Jonathan; Schröder, Martin

2018-03-05

The development of synthetic analogs of the active sites of [NiFe] hydrogenases remains challenging, and, in spite of the number of complexes featuring a [NiFe] center, those featuring CO and CN - ligands at the Fe center are under-represented. We report herein the synthesis of three bimetallic [NiFe] complexes [Ni( N 2 S 2 )Fe(CO) 2 (CN) 2 ], [Ni( S 4 )Fe(CO) 2 (CN) 2 ], and [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] that each contain a Ni center that bridges through two thiolato S donors to a {Fe(CO) 2 (CN) 2 } unit. X-ray crystallographic studies on [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ], supported by DFT calculations, are consistent with a solid-state structure containing distinct molecules in the singlet ( S = 0) and triplet ( S = 1) states. Each cluster exhibits irreversible reduction processes between -1.45 and -1.67 V vs Fc + /Fc and [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] possesses a reversible oxidation process at 0.17 V vs Fc + /Fc. Spectroelectrochemical infrared (IR) and electron paramagnetic resonance (EPR) studies, supported by density functional theory (DFT) calculations, are consistent with a Ni III Fe II formulation for [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + . The singly occupied molecular orbital (SOMO) in [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + is based on Ni 3d z 2 and 3p S with the S contributions deriving principally from the apical S-donor. The nature of the SOMO corresponds to that proposed for the Ni-C state of the [NiFe] hydrogenases for which a Ni III Fe II formulation has also been proposed. A comparison of the experimental structures, and the electrochemical and spectroscopic properties of [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] and its [Ni( N 2 S 3 )] precursor, together with calculations on the oxidized [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + and [Ni( N 2 S 3 )] + forms suggests that the binding of the {Fe(CO)(CN) 2 } unit to the {Ni(CysS) 4 } center at the active site of the [NiFe] hydrogenases suppresses thiolate-based oxidative chemistry involving the bridging thiolate S donors

Synthesis of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 ...

Indian Academy of Sciences (India)

School of Chemistry and Chemical Engineering, Anhui University of Technology, Ma'anshan 243002, ... superior to other approaches because of its high efficiency and low cost to ... pounds such as organic dyes.6,7 However, as using LDH for removal of dye ... separation of the absorbent by simply applying an external.

pH-Dependent isotope exchange and hydrogenation catalysed by water-soluble NiRu complexes as functional models for [NiFe]hydrogenases

OpenAIRE

Kure, Bunsho; Matsumoto, Takahiro; Ichikawa, Koji; Fukuzumi, Shunichi; Higuchi, Yoshiki; Yagi, Tatsuhiko; Ogo, Seiji

2008-01-01

The pH-dependent hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes and hydrogenation of the carbonyl compounds have been investigated with water-soluble bis(mu-thiolate)(mu-hydride)NiRu complexes, Ni(II)(mu-SR)(2)(mu-H)Ru(II) {(mu-SR)(2) = N,N'-dimethyl-N,N'-bis(2-mercaptoethyl)-1,3-propanediamine}, as functional models for [NiFe]hydrogenases. In acidic media (at pH 4-6), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes has H(+) properties, and the c...

Fabrication of a Co(OH)2/ZnCr LDH "p-n" Heterojunction Photocatalyst with Enhanced Separation of Charge Carriers for Efficient Visible-Light-Driven H2 and O2 Evolution.

Science.gov (United States)

Sahoo, Dipti Prava; Nayak, Susanginee; Reddy, K Hemalata; Martha, Satyabadi; Parida, Kulamani

2018-04-02

Photocatalytic generation of H 2 and O 2 by water splitting remains a great challenge for clean and sustainable energy. Taking into the consideration promising heterojunction photocatalysts, analogous energy issues have been mitigated to a meaningful extent. Herein, we have architectured a highly efficient bifunctional heterojunction material, i.e., p-type Co(OH) 2 platelets with an n-type ZnCr layered double hydroxide (LDH) by an ultrasonication method. Primarily, the Mott-Schottky measurements confirmed the n- and p-type semiconductive properties of LDH and CH material, respectively, with the construction of a p-n heterojunction. The high resolution transmission electron microscopy results suggest that surface modification of ZnCr LDH by Co(OH) 2 hexagonal platelets could form a fabulous p-n interfacial region that significantly decreases the energy barrier for O 2 and H 2 production by effectively separating and transporting photoinduced charge carriers, leading to enhanced photoreactivity. A deep investigation into the mechanism shows that a 30 wt % Co(OH) 2 -modified ZnCr LDH sample liberates maximum H 2 and O 2 production in 2 h, i.e., 1115 and 560 μmol, with apparent conversion efficiencies of H 2 and O 2 evolution of 13.12% and 6.25%, respectively. Remarkable photocatalytic activity with energetic charge pair transfer capability was illustrated by electrochemical impedance spectroscopy, linear sweep voltammetry, and photoluminescence spectra. The present study clearly suggests that low-cost Co(OH) 2 platelets are the most crucial semiconductors to provide a new p-n heterojunction photocatalyst for photocatalytic H 2 and O 2 production on the platform of ZnCr LDH.

Advances in the Function and Regulation of Hydrogenase in the Cyanobacterium Synechocystis PCC6803

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Cassier-Chauvat, Corinne; Veaudor, Théo; Chauvat, Franck

2014-01-01

In order to use cyanobacteria for the biological production of hydrogen, it is important to thoroughly study the function and the regulation of the hydrogen-production machine in order to better understand its role in the global cell metabolism and identify bottlenecks limiting H2 production. Most of the recent advances in our understanding of the bidirectional [Ni-Fe] hydrogenase (Hox) came from investigations performed in the widely-used model cyanobacterium Synechocystis PCC6803 where Hox is the sole enzyme capable of combining electrons with protons to produce H2 under specific conditions. Recent findings suggested that the Hox enzyme can receive electrons from not only NAD(P)H as usually shown, but also, or even preferentially, from ferredoxin. Furthermore, plasmid-encoded functions and glutathionylation (the formation of a mixed-disulfide between the cysteines residues of a protein and the cysteine residue of glutathione) are proposed as possible new players in the function and regulation of hydrogen production. PMID:25365180

Accuracy of PfHRP2 versus Pf-pLDH antigen detection by malaria rapid diagnostic tests in hospitalized children in a seasonal hyperendemic malaria transmission area in Burkina Faso

OpenAIRE

Maltha, Jessica; Guiraud, Issa; Lompo, Palpouguini; Kaboré, Bérenger; Gillet, Philippe; Van Geet, Chris; Tinto, Halidou; Jacobs, Jan

2014-01-01

Background In most sub-Saharan African countries malaria rapid diagnostic tests (RDTs) are now used for the diagnosis of malaria. Most RDTs used detect Plasmodium falciparum histidine-rich protein-2 (PfHRP2), though P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH)-detecting RDTs may have advantages over PfHRP2-detecting RDTs. Only few data are available on the use of RDTs in severe illness and the present study compared Pf-pLDH to PfHRP2-detection. Methods Hospitalized children...

Photoinduced reduction of the medial FeS center in the hydrogenase small subunit HupS from Nostoc punctiforme.

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Raleiras, Patrícia; Hammarström, Leif; Lindblad, Peter; Styring, Stenbjörn; Magnuson, Ann

2015-07-01

The small subunit from the NiFe uptake hydrogenase, HupSL, in the cyanobacterium Nostoc punctiforme ATCC 29133, has been isolated in the absence of the large subunit (P. Raleiras, P. Kellers, P. Lindblad, S. Styring, A. Magnuson, J. Biol. Chem. 288 (2013) 18,345-18,352). Here, we have used flash photolysis to reduce the iron-sulfur clusters in the isolated small subunit, HupS. We used ascorbate as electron donor to the photogenerated excited state of Ru(II)-trisbipyridine (Ru(bpy)3), to generate Ru(I)(bpy)3 as reducing agent. Our results show that the isolated small subunit can be reduced by the Ru(I)(bpy)3 generated through flash photolysis. Copyright © 2015 Elsevier Inc. All rights reserved.

Production and purification of a soluble hydrogenase from Ralstonia eutropha H16 for potential hydrogen fuel cell applications.

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Jugder, Bat-Erdene; Lebhar, Helene; Aguey-Zinsou, Kondo-Francois; Marquis, Christopher P

2016-01-01

The soluble hydrogenase (SH) from Ralstonia eutropha H16 is a promising candidate enzyme for H2-based biofuel application as it favours H2 oxidation and is relatively oxygen-tolerant. In this report, bioprocess development studies undertaken to produce and purify an active SH are described, based on the methods previously reported [1], [2], [3], [4]. Our modifications are: •Upstream method optimizations were undertaken on heterotrophic growth media and cell lysis involving ultrasonication.•Two anion exchangers (Q Sepharose and RESOURCE Q) and size exclusion chromatographic (Superdex 200) matrices were successfully employed for purification of a hexameric SH from R. eutropha.•The H2 oxidizing activity of the SH was demonstrated spectrophotometrically in solution and also immobilized on an EPG electrode using cyclic voltammetry.

Synthesis and characterization of LDH/Ppi composite and its application as adsorbent of 2,4-dichlorophenoxyacetic (herbicide); Sintese e caracterizacao do composito HDL/Ppi e sua aplicacao como adsorvente do 2,4-diclorofenoxiacetico (herbicida)

Energy Technology Data Exchange (ETDEWEB)

Pacheco, I.S.; Oliveira, R.S.; Girotto, L.G.; Freitas, L.L. de; Amaral, F.A. do; Canobre, S.C., E-mail: ingrid_1194@hotmail.com [Universidade Federal de Uberlandia (UFU), MG (Brazil). Instituto de Quimica

2016-07-01

This work had as main objective the synthesis and characterization of LDH [Co-Al-Cl] method by hydrolysis of urea and then its synthesized polypyrrole coating by chemically targeting the application as adsorbent dichlorophenoxyacetic acid (2,4-D). The x-ray diffractogram of well defined showed diffraction peaks corresponding to the planes 003, 006, 009 and 110 which allow them to rhombohedral indexes and lamellar structure. The composite LDH / Ppi had a percentage of 49% herbicide retention in aqueous solution. From the investigated adsorption isotherm models that more fit the experimental data was the Freundlich, so it could be inferred that the interaction between the LDH / Ppi and the herbicide was physical, ie an rapid, reversible adsorption and does not specify. (author)

HRP2 and pLDH-Based Rapid Diagnostic Tests, Expert Microscopy, and PCR for Detection of Malaria Infection during Pregnancy and at Delivery in Areas of Varied Transmission: A Prospective Cohort Study in Burkina Faso and Uganda.

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Daniel J Kyabayinze

Full Text Available Intermittent screening and treatment (IST of malaria during pregnancy has been proposed as an alternative to intermittent preventive treatment in pregnancy (IPTp, where IPTp is failing due to drug resistance. However, the antenatal parasitaemias are frequently very low, and the most appropriate screening test for IST has not been defined.We conducted a multi-center prospective study of 990 HIV-uninfected women attending ANC in two different malaria transmission settings at Tororo District Hospital, eastern Uganda and Colsama Health Center in western Burkina Faso. Women were enrolled in the study in the second or third trimester of pregnancy and followed to delivery, generating 2,597 blood samples for analysis. Screening tests included rapid diagnostic tests (RDTs targeting histidine-rich protein 2 (HRP2 and parasite lactate dehydrogenase (pLDH and microscopy, compared to nPCR as a reference standard. At enrolment, the proportion of pregnant women who were positive for P. falciparum by HRP2/pan pLDH RDT, Pf pLDH/pan pLDH RDT, microscopy and PCR was 38%, 29%, 36% and 44% in Uganda and 21%, 16%, 15% and 35% in Burkina Faso, respectively. All test positivity rates declined during follow-up. In comparison to PCR, the sensitivity of the HRP2/pan pLDH RDT, Pf pLDH/pan pLDH RDT and microscopy was 75.7%, 60.1% and 69.7% in Uganda, 55.8%, 42.6% and 55.8% in Burkina Faso respectively for all antenatal visits. Specificity was greater than 96% for all three tests. Comparison of accuracy using generalized estimating equation revealed that the HRP2- detecting RDT was the most accurate test in both settings.The study suggests that HRP2-based RDTs are the most appropriate point-of-care test currently available for use during pregnancy especially for symptomatic women, but will still miss some PCR-positive women. The clinical significance of these very low density infections needs to be better defined.

How Formaldehyde Inhibits Hydrogen Evolution by [FeFe]-Hydrogenases: Determination by ¹³C ENDOR of Direct Fe-C Coordination and Order of Electron and Proton Transfers.

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Bachmeier, Andreas; Esselborn, Julian; Hexter, Suzannah V; Krämer, Tobias; Klein, Kathrin; Happe, Thomas; McGrady, John E; Myers, William K; Armstrong, Fraser A

2015-04-29

Formaldehyde (HCHO), a strong electrophile and a rapid and reversible inhibitor of hydrogen production by [FeFe]-hydrogenases, is used to identify the point in the catalytic cycle at which a highly reactive metal-hydrido species is formed. Investigations of the reaction of Chlamydomonas reinhardtii [FeFe]-hydrogenase with formaldehyde using pulsed-EPR techniques including electron-nuclear double resonance spectroscopy establish that formaldehyde binds close to the active site. Density functional theory calculations support an inhibited super-reduced state having a short Fe-(13)C bond in the 2Fe subsite. The adduct forms when HCHO is available to compete with H(+) transfer to a vacant, nucleophilic Fe site: had H(+) transfer already occurred, the reaction of HCHO with the Fe-hydrido species would lead to methanol, release of which is not detected. Instead, Fe-bound formaldehyde is a metal-hydrido mimic, a locked, inhibited form analogous to that in which two electrons and only one proton have transferred to the H-cluster. The results provide strong support for a mechanism in which the fastest pathway for H2 evolution involves two consecutive proton transfer steps to the H-cluster following transfer of a second electron to the active site.

New Ideas for an Old Enzyme: A Short, Question-Based Laboratory Project for the Purification and Identification of an Unknown LDH Isozyme

Science.gov (United States)

Coleman, Aaron B.

2010-01-01

Enzyme purification projects are an excellent way to introduce many aspects of protein biochemistry, but can be difficult to carry out under the constraints of a typical undergraduate laboratory course. We have designed a short laboratory project for the purification and identification of an "unknown" lactate dehydrogenase (LDH) isozyme that can…

Expressão do Mg+2, CK, AST e LDH em equinos finalistas de provas de enduro

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Juliana V.F. Sales

2013-01-01

Full Text Available Nos últimos anos, o equino atleta vem sendo cada vez mais requerido. Dessa forma, as exigências por alto desempenho têm fomentado o interesse pelo estudo das afecções relacionadas com a fisiopatologia de diversas enfermidades dos equinos. A relação entre o íon magnésio e o exercício físico tem recebido atenção significativa visto que este íon está intimamente relacionado ao tecido muscular estriado esquelético. Além disso, dentre as principais estratégias para a detecção e acompanhamento clínico de lesões musculares, destacam-se a avaliação das atividades das enzimas creatino quinase (CK, lactato desidrogenase (LDH e aspartato aminotransferase (AST. A busca pelo estabelecimento de parâmetros que se relacionam entre si é um fator determinante na compreensão de alterações fisiológicas encontradas diante do esforço em equinos atletas. Desta forma, o presente trabalho teve como objetivo determinar como as concentrações sanguíneas do íon magnésio e as atividades enzimáticas das enzimas CK, LDH e AST comportaram-se em equinos Puro Sangue Árabe finalistas de provas de enduro de 90km e relacionar as possíveis alterações com o tipo de esforço físico desempenhado pelos animais. Foram avaliadas a atividade enzimática das enzimas CK, LDH, AST e a concentração do íon magnésio no exercício em relação ao repouso de 14 equinos clinicamente hígidos da raça Puro Sangue Árabe, sendo 9 machos e 5 fêmeas, com idades variando entre 6 a 12 anos, submetidos a treinamento para enduro e participantes de provas de 90 km. Pode-se observar que as variáveis acima mencionadas sofreram aumento com diferença estatística em relação ao repouso. O exercício físico de enduro determinou a ocorrência de alterações nas atividades enzimáticas das enzimas CK (p≤0,001, LDH (p=0,0001, AST (p=0,0007 e na concentração do íon magnésio (p=0,0004, no exercício em relação ao repouso (p≤0,05. Fato que determinou altera

PARÁMETROS BIOQUÍMICOS ENZIMÁTICOS (ALT, AST, ALP, Γ-GT, LDH EN NIÑOS CON LEUCEMIA LINFOBLÁSTICA AGUDA ANTES DEL TRATAMIENTO ANTINEOPLÁSICO

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Jeél Moya S

2015-12-01

Full Text Available Objective: To determine the enzymatic biochemical parameters (glutamic pyruvic transaminase (ALT, glutamic oxaloacetic transaminase (AST, alkaline phosphatase (ALP, gamma glutamyltransferase (γ-GT, and lactate dehydrogenase (LDH in children with acute lymphoblastic leukemia (ALL before cancer treatment. Material and Methods: A prospective experimental, observational, cross-sectional study was conducted in 30 children between 2 and 15 years old, from several Neoplastic Centers in Lima. Blood collection was performed in BD red cap Vacutainer tubes, processed in the semi-automated analyzer BIOTEC® EMP-168, with Wiener Lab Group enzyme reagents under the modified method Szaaz and UV-Optimized by IFCC, SSCC and SFBC. Finally, coding and tabulation was performed. Results: 60% were boys and 46.7% are between the ages of 2-6 years. Serum levels of AST were increased by 33.3% in boys and 50% in girls. Serum ALT values were increased in 33.3% of boys and 41.7% of girls; only 25% of girls showed increased levels of γ-GT values; ALP was increased in 44.4% of boys and 66.7% of girls. Moreover LDH levels were increased in 55.6% of boys and 41.7% of girls. Conclusions: The enzymatic tests LDH, AST, ALT and ALP are increased in children with ALL compared to normal values due to tumor lysis syndrome characterized by electrolyte abnormalities, and as a result of the massive destruction of tumor cells and rapid release of large amounts of intracellular elements.

Sonochemical surface functionalization of exfoliated LDH: Effect on textural properties, CO2 adsorption, cyclic regeneration capacities and subsequent gas uptake for simultaneous methanol synthesis.

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Ezeh, Collins I; Huang, Xiani; Yang, Xiaogang; Sun, Cheng-Gong; Wang, Jiawei

2017-11-01

To improve CO 2 adsorption, amine modified Layered double hydroxide (LDH) were prepared via a two stage process, SDS/APTS intercalation was supported by ultrasonic irradiation and then followed by MEA extraction. The prepared samples were characterised using Scanning electron microscope-Energy dispersive X-ray spectroscopy (SEM-EDX), X-ray Photoelectron Spectroscopy (XPS), X-ray diffraction (XRD), Temperature Programmed Desorption (TPD), Brunauer-Emmett-Teller (BET), and Thermogravimetric analysis (TGA), respectively. The characterisation results were compared with those obtained using the conventional preparation method with consideration to the effect of sonochemical functionalization on textural properties, adsorption capacity, regeneration and lifetime of the LDH adsorbent. It is found that LDHs prepared by sonochemical modification had improved pore structure and CO 2 adsorption capacity, depending on sonic intensity. This is attributed to the enhanced deprotonation of activated amino functional groups via the sonochemical process. Subsequently, this improved the amine loading and effective amine efficiency by 60% of the conventional. In addition, the sonochemical process improved the thermal stability of the adsorbent and also, reduced the irreversible CO 2 uptake, CUirrev, from 0.18mmol/g to 0.03mmol/g. Subsequently, improving the lifetime and ease of regenerating the adsorbent respectively. This is authenticated by subjecting the prepared adsorbents to series of thermal swing adsorption (TSA) cycles until its adsorption capacity goes below 60% of the original CO 2 uptake. While the conventional adsorbent underwent a 10 TSA cycles before breaking down, the sonochemically functionalized LDH went further than 30 TSA cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

Multivariate optimization of process parameters in the synthesis of calcined Ca‒Al (NO3) LDH for defluoridation using 3(3) factorial, central composite and Box-Behnken design.

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Ghosal, Partha S; Gupta, Ashok K; Sulaiman, Ayoob

2016-01-01

Response surface methodology was applied for the first time in the optimization of the preparation of layered double hydroxide (LDH) for defluoridation. The influence of three vital process parameters (viz. pH, molar ratio and calcination temperature) in the synthesis of the adsorbent 'Calcined Ca‒Al (NO3) LDH' was thoroughly examined to maximize its fluoride scavenging potential. The process parameters were optimized using the 3(3) factorial, face centered central composite and Box-Behnken designs and a comparative assessment of the methods was conducted. The maximum fluoride removal efficiency was achieved at a calcination temperature of approximately 500ºC; however, the efficiency decreased with increasing pH and molar ratio. The outcome of the comparative assessment clearly delineates the case specific nature of the models. A better predictability over the entire experimental domain was obtained with the 3(3) factorial method, whereas the Box-Behnken design was found to be the most efficient model with lesser number of experimental runs. The desirability function technique was performed for optimizing the response, wherein face centered central composite design exhibited a maximum desirability. The calcined Ca‒Al (NO3) LDH, synthesized under the optimum conditions, demonstrated the removal efficiencies of 95% and 99% for the doses of 3 g L(-1) and 5 g L(-1), respectively.

Preparation of nano composite latex of poly(butyl acrylate-co-methyl methacrylate) P (BA-co-MMA) and layered double hydroxide (LDH) by mini emulsion polymerization; Preparacao de latex nanocomposito de poli(acrilato de butila-co-metacrilato de metila) P (BA-co-MMA) e hidroxido duplo lamelar (HDL) por meio da tecnica de polimerizacao em miniemulsao

Energy Technology Data Exchange (ETDEWEB)

Silva, Rodrigo D; Lona, Liliane M.F., E-mail: liliane@feq.unicamp.br [Universidade Estadual de Campinas - Unicamp, Faculdade de Engenharia Quimica, SP (Brazil); Dube, Marc A [Universidade de Ottawa. Departamento de Engenharia Quimica e Biologica, Ottawa, ON (Canada)

2011-07-01

In the present work, the synthesis of polymeric nonconsumption (PNCs) of P(BA-coMMA) and layered LDH through mini emulsion polymerization (MEP) was studied. The commercial organically modified LDH Perkalite F100S was used as filler and octadecyl acrylate (ODA) as costabilizer of the mini emulsions. Two types of surfactant, a cationic and nonionic one, were investigated and the cationic one could not stabilize the system when the LDH was present. The polymerization kinetics was not significantly affected by the presence of LDH which kept the pH of the system constant during the reaction. The dispersion of the inorganic material in the polymeric matrix was evaluated by X-ray diffraction which suggested exfoliation of the LDH. (author)

Effective inhibition of colon cancer cell growth with MgAl-layered double hydroxide (LDH loaded 5-FU and PI3K/mTOR dual inhibitor BEZ-235 through apoptotic pathways

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Chen J

2014-07-01

Full Text Available Jiezhong Chen,1,2 Renfu Shao,3 Li Li,4 Zhi Ping Xu,4 Wenyi Gu4 1School of Biomedical Sciences, University of Queensland, St Lucia, Queensland, 2Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, New South Wales, 3GeneCology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, 4Australian Institute of Bioengineering and Nanotechnology, University of Queensland, St Lucia, Queensland, Australia Abstract: Colon cancer is the third most common cancer and the third largest cause of cancer-related death. Fluorouracil (5-FU is the front-line chemotherapeutic agent for colon cancer. However, its response rate is less than 60%, even in combination with other chemotherapeutic agents. The side effects of 5-FU also limit its application. Nanoparticles have been used to deliver 5-FU, to increase its effectiveness and reduce side effects. Another common approach for colon cancer treatment is targeted therapy against the phosphoinositide 3-kinase (PI3K/protein kinase B (Akt pathway. A recently-invented inhibitor of this pathway, BEZ-235, has been tested in several clinical trials and has shown effectiveness and low side effects. Thus, it is a very promising drug for colon cancer treatment. The combination of these two drugs, especially nanoparticle-packed 5-FU and BEZ-235, has not been studied. In the present study, we demonstrated that nanoparticles of layered double hydroxide (LDH loaded with 5-FU were more effective than a free drug at inhibiting colon cancer cell growth, and that a combination treatment with BEZ-235 further increased the sensitivity of colon cancer cells to the treatment of LDH-packed 5-FU (LDH-5-FU. BEZ-235 alone can decrease colon cancer HCT-116 cell viability to 46% of the control, and the addition of LDH-5-FU produced a greater effect, reducing cell survival to 8% of the control. Our data indicate that the combination therapy of

Investigation of hydrogenase molecular marker to optimize hydrogen production from organic wastes and effluents of agro-food industries [abstract

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Hamilton, C.

2010-01-01

Full Text Available In recent years policy makers have started looking for alternatives to fossil fuels, not only to counter the threat of global warming, but also to reduce the risk of overdependence on imported oil and gas supplies. By contrast with hydrocarbon fuels, hydrogen (H2, whether burned directly or used in fuel cells, is intrinsically a clean energy vector with near zero emission. However the main current method of producing hydrogen, steam reforming of methane, involves the release of large quantities of greenhouse gases. So although hydrogen already accounts for around 2% of world consumption of energy, its more widespread adoption is limited by several challenges. Therefore new processes are investigated, especially those using renewable raw material, e.g. woods and organic wastes, and/or involving microorganisms. Indeed, for some algae and bacteria, the generation of molecular hydrogen is an essential part of their energy metabolism. The approach with the greatest commercial potential is fermentative hydrogen generation (dark fermentation by bacteria from the Clostridium genus. This biological process, as a part of the methane-producing anaerobic digestion process, is very promising since it allows the production of hydrogen from a wide variety of renewable resources such as carbohydrate waste from the agricultural and agro-food industries or processed urban waste and sewage. To date most publications on hydrogen production by Clostridium strains have focused on the effects of operating parameters (such as temperature, pH, dilution rate, etc.. We now need to extend this knowledge by identifying and monitoring the various different metabolic agents involved in high H2 activity. Consequently the aim of this research at the CWBI in the University of Liege is to investigate the role of [Fe] hydrogenases, the key enzymes that remove excess electrons accumulating during fermentation. Clostridium butyricum CWBI1009, the strain used for these investigations

Alizarin red S dye removal from contaminated water on calcined [Mg/Al, Zn/Al and MgZn/Al]-LDH

Science.gov (United States)

Aissat, Miloud; Hamouda, Sara; Benhadria, Naceur; Chellali, Rachid; Bettahar, Noureddine

2018-05-01

The waste water rejected by the textile industries is loaded with organic dyes, responsible for the high color present in the effluents. Some dyes and / or their degradation products could be carcinogenic and may have mutagenic properties. The rapid growth of the global economy has caused many environmental problems with a huge pollution problem. The abuse use of chemicals product is an environmental toxicological problem. The consequences can be serious for water resources. In this perspective, our study comes to participate with new means of depollution using new materials with interesting properties in the treatment of pollution. Among these materials, LDHs whose synthesis is easy and inexpensive can be a tool in the treatment of water Polluted [1]. Our contribution consists in using HDL as a means of sorption of dyes which are considered as polluting agents of waters especially for the industry textile. This study considers the removal of the Alizarine Red S (AR) from water on calcined MgAl,ZnAL and MgZnAL-layered double hydroxides. The different LDH was prepared by copreprecipation method. The materials was obtained for molar ratios R =2 for the different LDH. The carbonated layered Calcination of these solids leads to the formation of mixed oxides which have the property of being able to be regenerated by adsorbing new anionic entities. Adsorbents and adsorption products were characterized by physicochemical techniques. The structural characterization of the material was carried out by X-ray diffraction, infrared spectroscopy (FTIR). Dosages of the polluted solutions were monitored by UV-Visible spectrometry.

Hydrogen evolution in [NiFe] hydrogenases and related biomimetic systems: similarities and differences.

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Das, Ranjita; Neese, Frank; van Gastel, Maurice

2016-09-21

In this work, a detailed quantum chemical study of the mechanism of [Ni(bdt)(dppf)] (Ni(II)L) catalyzed hydrogen formation [A. Gan, T. L. Groy, P. Tarakeshwar, S. K. S. Mazinani, J. Shearer, V. Mujica and A. K. Jones, J. Am. Chem. Soc., 2015, 137, 1109-1115] following an electro-chemical-electro-chemical (ECEC) pathway is reported. The complex exclusively catalyzes the reduction of protons to molecular hydrogen. The calculations suggest that the first one-electron reduction of the [Ni(II)L] catalyst is the rate limiting step of the catalytic cycle and hence, the buildup of detectable reaction intermediates is not expected. The catalytic activity of the [Ni(II)L] complex is facilitated by the flexibility of the ligand system, which allows the ligand framework to adapt to changes in the Ni oxidation state over the course of the reaction. Additionally, a comparison is made with the catalytic activity of [NiFe] hydrogenase. It is argued that the directionality of the reversible hydrogen formation reaction is controlled by the ligand field of the nickel ion and the possibility for side-on (η(2)) binding of H2: if the ligand framework does not allow for η(2) binding of H2, as is the case for [Ni(II)L], the catalyst irreversibly reduces protons. If the ligand field allows η(2) binding of H2, the catalyst can in principle work reversibly. The conditions for η(2) binding are discussed.

Synthesis of Co-Al-Cl LDH by cathodic material reprocessing from cellular phone batteries

Energy Technology Data Exchange (ETDEWEB)

Amaral, Fabio Augusto do; Machado, Erica Oliveira; Freitas, Leonardo Luis de; Santana, Laiane Kalita; Canobre, Sheila Cristina, E-mail: fabioamaral@yahoo.com.br, E-mail: fabioamaral@iqufu.ufu.br [Universidade Federal de Uberlandia (UFU/LAETE), (Brazil). Inst. de Quimica. Lab. de Armazenamento de Energia e Tratamento de Efluente

2014-08-15

The aim of this paper was the recovering of the cathodic material from discarded lithium ion batteries for obtainment of the lamellar double hydroxides (LDHs) by the co-precipitation method at variable pH in HCl and H{sub 2}O{sub 2} 1:1 (v/v) acid solution containing Co and Al (extracted from cathodic material composed of LiCoO{sub 2} and aluminum foil). These metals were precipitated in LiOH at pH 9 or 11, or NH{sub 4}OH at pH 9 and submitted to the hydrothermal treatment (HT) to improve the structural organization of the LDHs lamellae. After precipitation, the resulting solids were structurally characterized by XRD for phase identification and calculation of the unit cell parameter, thermally by TGA for the identification of the mass loss and morphologically by SEM. The sample obtained by precipitation with LiOH at pH 11 / hydrothermal treatment showed diffraction peaks similar to hydrotalcite, morphological and thermal characteristics similar to the pattern Co-Al-Cl LDH obtained by co-precipitation at constant pH 8. (author)

Electrochemistry of metalloproteins: protein film electrochemistry for the study of E. coli [NiFe]-hydrogenase-1.

Science.gov (United States)

Evans, Rhiannon M; Armstrong, Fraser A

2014-01-01

Protein film electrochemistry is a technique which allows the direct control of redox-active enzymes, providing particularly detailed information on their catalytic properties. The enzyme is deposited onto a working electrode tip, and through control of the applied potential the enzyme activity is monitored as electrical current, allowing for direct study of inherent activity as electrons are transferred to and from the enzyme redox center(s). No mediators are used. Because the only enzyme present in the experiment is bound at the electrode surface, gaseous and liquid phase inhibitors can be introduced and removed whilst the enzyme remains in situ. Potential control means that kinetics and thermodynamics are explored simultaneously; the kinetics of a reaction can be studied as a function of potential. Steady-state catalytic rates are observed directly as current (for a given potential) and non-steady-state rates (such as interconversions between different forms of the enzyme) are observed from the change in current with time. The more active the enzyme, the higher the current and the better the signal-to-noise. In this chapter we outline the practical aspects of PFE for studying electroactive enzymes, using the Escherichia coli [NiFe]-hydrogenase 1 (Hyd-1) as an example.

Hydrogen Activation by Biomimetic [NiFe]-Hydrogenase Model Containing Protected Cyanide Cofactors

Science.gov (United States)

Manor, Brian C.; Rauchfuss, Thomas B.

2013-01-01

Described are experiments that allow incorporation of cyanide cofactors and hydride substrate into active site models [NiFe]-hydrogenases (H2ases). Complexes of the type (CO)2(CN)2Fe(pdt)Ni(dxpe), (dxpe = dppe, 1; dxpe = dcpe, 2) bind the Lewis acid B(C6F5)3 (BArF3) to give the adducts (CO)2(CNBArF3)2Fe(pdt)Ni(dxpe), (1(BArF3)2, 2(BArF3)2). Upon decarbonylation using amine oxides, these adducts react with H2 to give hydrido derivatives Et4N[(CO)(CNBArF3)2Fe(H)(pdt)Ni(dxpe)], (dxpe = dppe, Et4N[H3(BArF3)2]; dxpe = dcpe, Et4N[H4(BArF3)2]). Crystallographic analysis shows that Et4N[H3(BArF3)2] generally resembles the active site of the enzyme in the reduced, hydride-containing states (Ni-C/R). The Fe-H…Ni center is unsymmetrical with rFe-H = 1.51(3) and rNi-H = 1.71(3) Å. Both crystallographic and 19F NMR analysis show that the CNBArF3− ligands occupy basal and apical sites. Unlike cationic Ni-Fe hydrides, [H3(BArF3)2]− and [H4(BArF3)2]− oxidize at mild potentials, near the Fc+/0 couple. Electrochemical measurements indicate that in the presence of base, [H3(BArF3)2]− catalyzes the oxidation of H2. NMR evidence indicates dihydrogen bonding between these anionic hydrides and ammonium salts, which is relevant to the mechanism of hydrogenogenesis. In the case of Et4N[H3(BArF3)2], strong acids such as HCl induce H2 release to give the chloride Et4N[(CO)(CNBArF3)2Fe(pdt)(Cl)Ni(dppe)]. PMID:23899049

Effects of biomass-generated producer gas constituents on cell growth, product distribution and hydrogenase activity of Clostridium carboxidivorans P7T

International Nuclear Information System (INIS)

Ahmed, Asma; Cateni, Bruno G.; Huhnke, Raymond L.; Lewis, Randy S.

2006-01-01

In our previous work, we demonstrated that biomass-generated producer gas can be converted to ethanol and acetic acid using a microbial catalyst Clostridium carboxidivorans P7 T . Results showed that the producer gas (1) induced cell dormancy, (2) inhibited H 2 consumption, and (3) affected the acetic acid/ethanol product distribution. Results of this work showed that tars were the likely cause of cell dormancy and product redistribution and that the addition of a 0.025μm filter in the gas cleanup negated the effects of tars. C. carboxidivorans P7 T can adapt to the tars (i.e. grow) only after prolonged exposure. Nitric oxide, present in the producer gas at 150ppm, is an inhibitor of the hydrogenase enzyme involved in H 2 consumption. We conclude that significant conditioning of the producer gas will be required for the successful coupling of biomass-generated producer gas with fermentation to produce ethanol and acetic acid. (author)

Repercussões da L-alanil-glutamina sobre as concentrações de lactato e lactato desidrogenase (LDH em pacientes com isquemia crítica dos membros inferiores submetidos a revascularização distal Repercussions of l-alanyl-glutamine upon the concentrations of lactate and lactate dehydrogenase (LDH in patients with critical ischemia of lower limbs subjected to distal revascularization

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Wellington Forte Alves

2003-06-01

Full Text Available OBJETIVO: Investigar efeitos da L-alanil-glutamina nas concentrações musculares de lactato, e nas concentrações sanguíneas de LDH, em pacientes com isquemia crítica dos membros inferiores submetidos à revascularização distal. MÉTODOS: Dezesseis adultos (12-homens/4-mulheres foram distribuídos em 2 grupos (1-controle/2-estudo. Três horas após injeção endovenosa de 250 ml de L-alanil-glutamina a 20% adicionados a 750 ml de soro fisiológico (Grupo 2, ou 1000 ml de solução salina (Grupo 1, iniciava-se a revascularização, sob raquianestesia. Amostras musculares e de sangue (arterial/venoso foram coletadas no início do procedimento (TI, no final (TF, e 10 e 20 minutos após isquemia (T1/T2. RESULTADOS: Observou-se redução significante (pPURPOSE: Investigate the repercussions of L-alanyl-glutamine in muscular tissue concentrations of lactate, and venous and arterial blood concentrations of LDH, in patients with critical ischemia of the lower limbs submitted to distal revascularization. METHODS: Sixteen adults (12 male/4 female were distributed in 2 groups (1-Control/2-Experiment. Three hours after the intravenous injection of 250 ml of a 20% solution of L-alanyl-glutamine added to 750 ml of saline solution (Group 2; or 1000 ml of saline solution (Group 1, distal bypass was carried out under spinal anesthesia. Muscle and blood samples (arterial/venous were collected at the beginning of the surgical procedure (TI, at the end (TF, and 10 and 20 minutes after re-establishment of blood flow. RESULTS: Significant reduction (p<0,05 of lactate concentration was observed in healthy muscle tissue in L-alanyl-glutamine treated patients in comparison to control group, at all times studied. There was a significant reduction (p <0,05 in venous concentrations of LDH in treated patients at all times studied (TI/TFV/T1V/T2V; and in arterial blood during reperfusion (T1A/T2A. CONCLUSIONS: 1. Decreased lactate concentrations in healthy skeletal

A [4Fe-4S]-Fe(CO)(CN)-l-cysteine intermediate is the first organometallic precursor in [FeFe] hydrogenase H-cluster bioassembly

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Rao, Guodong; Tao, Lizhi; Suess, Daniel L. M.; Britt, R. David

2018-05-01

Biosynthesis of the [FeFe] hydrogenase active site (the 'H-cluster') requires the interplay of multiple proteins and small molecules. Among them, the radical S-adenosylmethionine enzyme HydG, a tyrosine lyase, has been proposed to generate a complex that contains an Fe(CO)2(CN) moiety that is eventually incorporated into the H-cluster. Here we describe the characterization of an intermediate in the HydG reaction: a [4Fe-4S][(Cys)Fe(CO)(CN)] species, 'Complex A', in which a CO, a CN- and a cysteine (Cys) molecule bind to the unique 'dangler' Fe site of the auxiliary [5Fe-4S] cluster of HydG. The identification of this intermediate—the first organometallic precursor to the H-cluster—validates the previously hypothesized HydG reaction cycle and provides a basis for elucidating the biosynthetic origin of other moieties of the H-cluster.

Effects of biomass-generated producer gas constituents on cell growth, product distribution and hydrogenase activity of Clostridium carboxidivorans P7{sup T}

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Asma [Oklahoma State University, Stillwater, OK (United States). School of Chemical Engineering; Cateni, Bruno G.; Huhnke, Raymond L. [Oklahoma State University, Stillwater, OK (United States). Department of Biosystems and Agricultural Engineering; Lewis, Randy S. [Brigham Young University, Provo, UT (United States). Chemical Engineering Department

2006-07-15

In our previous work, we demonstrated that biomass-generated producer gas can be converted to ethanol and acetic acid using a microbial catalyst Clostridium carboxidivorans P7{sup T}. Results showed that the producer gas (1) induced cell dormancy, (2) inhibited H{sub 2} consumption, and (3) affected the acetic acid/ethanol product distribution. Results of this work showed that tars were the likely cause of cell dormancy and product redistribution and that the addition of a 0.025{mu}m filter in the gas cleanup negated the effects of tars. C. carboxidivorans P7{sup T} can adapt to the tars (i.e. grow) only after prolonged exposure. Nitric oxide, present in the producer gas at 150ppm, is an inhibitor of the hydrogenase enzyme involved in H{sub 2} consumption. We conclude that significant conditioning of the producer gas will be required for the successful coupling of biomass-generated producer gas with fermentation to produce ethanol and acetic acid. (author)

Roles of the twin-arginine translocase and associated chaperones in the biogenesis of the electron transport chains of the human pathogen Campylobacter jejuni.

Science.gov (United States)

Hitchcock, Andrew; Hall, Stephen J; Myers, Jonathan D; Mulholland, Francis; Jones, Michael A; Kelly, David J

2010-10-01

The zoonotic pathogen Campylobacter jejuni NCTC 11168 uses a complex set of electron transport chains to ensure growth with a variety of electron donors and alternative electron acceptors, some of which are known to be important for host colonization. Many of the key redox proteins essential for electron transfer in this bacterium have N-terminal twin-arginine translocase (TAT) signal sequences that ensure their transport across the cytoplasmic membrane in a folded state. By comparisons of 2D gels of periplasmic extracts, gene fusions and specific enzyme assays in wild-type, tatC mutant and complemented strains, we experimentally verified the TAT dependence of 10 proteins with an N-terminal twin-arginine motif. NrfH, which has a TAT-like motif (LRRKILK), was functional in nitrite reduction in a tatC mutant, and was correctly rejected as a TAT substrate by the tatfind and TatP prediction programs. However, the hydrogenase subunit HydA is also rejected by tatfind, but was shown to be TAT-dependent experimentally. The YedY homologue Cj0379 is the only TAT translocated molybdoenzyme of unknown function in C. jejuni; we show that a cj0379c mutant is deficient in chicken colonization and has a nitrosative stress phenotype, suggestive of a possible role for Cj0379 in the reduction of reactive nitrogen species in the periplasm. Only two potential TAT chaperones, NapD and Cj1514, are encoded in the genome. Surprisingly, despite homology to TorD, Cj1514 was shown to be specifically required for the activity of formate dehydrogenase, not trimethylamine N-oxide reductase, and was designated FdhM.

Oxamate, but Not Selective Targeting of LDH-A, Inhibits Medulloblastoma Cell Glycolysis, Growth and Motility

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Cara J. Valvona

2018-03-01

Full Text Available Medulloblastoma is the most common malignant paediatric brain tumour and current therapies often leave patients with severe neurological disabilities. Four major molecular groups of medulloblastoma have been identified (Wnt, Shh, Group 3 and Group 4, which include additional, recently defined subgroups with different prognosis and genetic characteristics. Lactate dehydrogenase A (LDHA is a key enzyme in the aerobic glycolysis pathway, an abnormal metabolic pathway commonly observed in cancers, associated with tumour progression and metastasis. Studies indicate MBs have a glycolytic phenotype; however, LDHA has not yet been explored as a therapeutic target for medulloblastoma. LDHA expression was examined in medulloblastoma subgroups and cell lines. The effects of LDHA inhibition by oxamate or LDHA siRNA on medulloblastoma cell line metabolism, migration and proliferation were examined. LDHA was significantly overexpressed in Group 3 and Wnt MBs compared to non-neoplastic cerebellum. Furthermore, we found that oxamate significantly attenuated glycolysis, proliferation and motility in medulloblastoma cell lines, but LDHA siRNA did not. We established that aerobic glycolysis is a potential therapeutic target for medulloblastoma, but broader LDH inhibition (LDHA, B, and C may be more appropriate than LDHA inhibition alone.

Results of radioiodine therapy of manifest hyperthyroidism and autonomous euthyroid goiter

International Nuclear Information System (INIS)

Berding, G.; Schicha, H.

1990-01-01

In 200 patients follow-up examinations were performed up to one year after radioiodine therapy (RITh) with individual dose calculation. The mean applied dose was significantly lower in patients with immunogenic hyperhyroidism (Graves' disease) as compared to patients with non-immunogenic hyperthyroidism (disseminated/multifocal autonomy, HYDA). In Graves' disease the rate of recurrent hyperthyroidism was significantly higher and that of posttreatment hypothyroidism lower. Considering the high recurrence rate in Graves' disease a higher dose, e.g. 150 Gy, seems to be appropriate. In patients with HYDA who received antithyroid drugs during RITh, recurrence of hyperthyroidism appeared slightly more, and posttreatment hypothyroidism slightly less, frequent. The efficiency of RITh was not significantly reduced by additional treatment with antithyroid drugs. Posttreatment hypothyroidism in patients with euthyroid goiter and disseminated/multifocal autonomy (EUDA) occurred significnatly more frequent if the basal TSH level was ≥ 0.5 μIE/ml before therapy. The goiter size was reduced independent of the basal TSH level. In HYDA patients after thyroid surgery recurrence appeared less, and in those with EUDA posttreatment hypothyroidism significantly more, frequent. A lower dose seems to be suitable in patients who underwent thyroid surgery before. In patients with focal autonomy after RITh no recurrence of hyperthyroidism was observed. In 9% a suppressed basal TSH level indicating persistent autonomy was seen. Posttreatment hypothyroidism in focal autonomy appeared only in patients without manifest hyperthyroidism before RITh and was significantly more frequent in this group. In patients with focal autonomy who developed hypothyroidism the dose calculation was based on a significantly higher volume of the adenoma. (orig./MG) [de

pH-Dependent isotope exchange and hydrogenation catalysed by water-soluble NiRu complexes as functional models for [NiFe]hydrogenases.

Science.gov (United States)

Kure, Bunsho; Matsumoto, Takahiro; Ichikawa, Koji; Fukuzumi, Shunichi; Higuchi, Yoshiki; Yagi, Tatsuhiko; Ogo, Seiji

2008-09-21

The pH-dependent hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes and hydrogenation of the carbonyl compounds have been investigated with water-soluble bis(mu-thiolate)(mu-hydride)NiRu complexes, Ni(II)(mu-SR)(2)(mu-H)Ru(II) {(mu-SR)(2) = N,N'-dimethyl-N,N'-bis(2-mercaptoethyl)-1,3-propanediamine}, as functional models for [NiFe]hydrogenases. In acidic media (at pH 4-6), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes has H(+) properties, and the complexes catalyse the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes. A mechanism of the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes through a low-valent Ni(I)(mu-SR)(2)Ru(I) complex is proposed. In contrast, in neutral-basic media (at pH 7-10), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes acts as H(-), and the complexes catalyse the hydrogenation of carbonyl compounds.

Field evaluation of a PfHRP-2/pLDH rapid diagnostic test and light microscopy for diagnosis and screening of falciparum malaria during the peak seasonal transmission in an endemic area in Yemen.

Science.gov (United States)

Alareqi, Lina M Q; Mahdy, Mohammed A K; Lau, Yee-Ling; Fong, Mun-Yik; Abdul-Ghani, Rashad; Ali, Arwa A; Cheong, Fei-Wen; Tawfek, Rehab; Mahmud, Rohela

2016-01-28

Malaria is a public health threat in Yemen, with 149,451 cases being reported in 2013. Of these, Plasmodium falciparum represents 99%. Prompt diagnosis by light microscopy (LM) and rapid diagnostic tests (RTDs) is a key element in the national strategy of malaria control. The heterogeneous epidemiology of malaria in the country necessitates the field evaluation of the current diagnostic strategies, especially RDTs. Thus, the present study aimed to evaluate LM and an RDT, combining both P. falciparum histidine-rich protein-2 (PfHRP-2) and Plasmodium lactate dehydrogenase (pLDH), for falciparum malaria diagnosis and survey in a malaria-endemic area during the transmission season against nested polymerase chain reaction (PCR) as the reference method. A household-based, cross-sectional malaria survey was conducted in Mawza District, a malaria-endemic area in Taiz governorate. A total of 488 participants were screened using LM and PfHRP-2/pLDH RDT. Positive samples (160) and randomly selected negative samples (52) by both RDT and LM were further analysed using 18S rRNA-based nested PCR. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the RDT were 96.0% (95% confidence interval (CI): 90.9-98.3), 56.0% (95% CI: 44.7-66.8), 76.3% (95% CI: 69.0-82.3), and 90.4% (95% CI: 78.8-96.8), respectively. On the other hand, LM showed sensitivity of 37.6% (95% CI: 29.6-46.3), specificity of 97.6% (95% CI: 91.7-99.7), PPV of 95.9% (95% CI: 86.3-98.9), and NPV of 51.3% (95% CI: 43.2-59.2). The sensitivity of LM dropped to 8.5% for detecting asymptomatic malaria. Malaria prevalence was 32.8% (32.1 and 37.5% for ≥10 and <10 years, respectively) with the RDT compared with 10.7% (10.8 and 9.4% for age groups of ≥10 and <10 years, respectively) with LM. Among asymptomatic malaria individuals, LM and RDT-based prevalence rates were 1.6 and 25.6%, respectively. However, rates of 88.2 and 94.1% of infection with P. falciparum were found

Redox reactions of [FeFe]-hydrogenase models containing an internal amine and a pendant phosphine.

Science.gov (United States)

Zheng, Dehua; Wang, Mei; Chen, Lin; Wang, Ning; Sun, Licheng

2014-02-03

A diiron dithiolate complex with a pendant phosphine coordinated to one of the iron centers, [(μ-SCH2)2N(CH2C6H4-o-PPh2){Fe2(CO)5}] (1), was prepared and structurally characterized. The pendant phosphine is dissociated together with a CO ligand in the presence of excess PMe3, to afford [(μ-SCH2)2N(CH2C6H4-o-PPh2){Fe(CO)2(PMe3)}2] (2). Redox reactions of 2 and related complexes were studied in detail by in situ IR spectroscopy. A series of new Fe(II)Fe(I) ([3](+) and [6](+)), Fe(II)Fe(II) ([4](2+)), and Fe(I)Fe(I) (5) complexes relevant to Hox, Hox(CO), and Hred states of the [FeFe]-hydrogenase active site were detected. Among these complexes, the molecular structures of the diferrous complex [4](2+) with the internal amine and the pendant phosphine co-coordinated to the same iron center and the triphosphine diiron complex 5 were determined by X-ray crystallography. To make a comparison, the redox reactions of an analogous complex, [(μ-SCH2)2N(CH2C6H5){Fe(CO)2(PMe3)}2] (7), were also investigated by in situ IR spectroscopy in the absence or presence of extrinsic PPh3, which has no influence on the oxidation reaction of 7. The pendant phosphine in the second coordination sphere makes the redox reaction of 2 different from that of its analogue 7.

Fabrication of hydrogenase-cationic electrolyte biohybrids at interfaces and their electrochemical properties in Langmuir-Blodgett films

International Nuclear Information System (INIS)

Liu An; Zorin, Nikolay A.; Nakamura, Chikashi; Miyake, Jun; Qian Dongjin

2010-01-01

Hydrogenase (H 2 ase)-cationic electrolyte biohybrids were assembled at the air-water interface via intermolecular electrostatic interaction. The H 2 ase used was purified from the phototropic bacterium of Thiocapsa roseopersicina. Two kinds of cationic electrolyte compounds (CECs) were used, the difference of which was whether they contained viologen substituent or not. Surface pressure-area isotherms indicated that these CECs were co-existed with the H 2 ase in the monolayers, which were then transferred to substrate surfaces to form H 2 ase-CECs hybrid films by the Langmuir-Blodgett (LB) method. Uniform film was formed when polyelectrolyte was used as the subphase. Cyclic voltammograms (CVs) of the LB films showed a couple of redox waves in the potential range of -0.4 to -0.65 V vs. Ag/AgCl, which was ascribed to one electron process of either [4Fe-4S] clusters of H 2 ase or viologens of the CECs. A direct electron transfer between the H 2 ase and electrode surface was achieved in the LB films. Stronger current intensity was recorded when the CV measurements were done in H 2 saturated electrolyte solution than that in Ar. It was confirmed that the H 2 ase biocatalytic activity remained in the LB films. Thus, we suggest that the present H 2 ase-CECs biohybrids could act as potential materials for the studies of interconversion reaction of H 2 and protons.

Metabolic markers in relation to hypoxia; staining patterns and colocalization of pimonidazole, HIF-1α, CAIX, LDH-5, GLUT-1, MCT1 and MCT4

International Nuclear Information System (INIS)

Rademakers, Saskia E; Lok, Jasper; Kogel, Albert J van der; Bussink, Johan; Kaanders, Johannes HAM

2011-01-01

The cellular response of malignant tumors to hypoxia is diverse. Several important endogenous metabolic markers are upregulated under hypoxic conditions. We examined the staining patterns and co-expression of HIF-1α, CAIX, LDH-5, GLUT-1, MCT1 and MCT4 with the exogenous hypoxic cell marker pimonidazole and the association of marker expression with clinicopathological characteristics. 20 biopsies of advanced head and neck carcinomas were immunohistochemically stained and analyzed. All patients were given the hypoxia marker pimonidazole intravenously 2 h prior to biopsy taking. The tumor area positive for each marker, the colocalization of the different markers and the distribution of the markers in relation to the blood vessels were assessed by semiautomatic quantitative analysis. MCT1 staining was present in hypoxic (pimonidazole stained) as well as non-hypoxic areas in almost equal amounts. MCT1 expression showed a significant overall correlation (r = 0.75, p < 0.001) and strong spatial relationship with CAIX. LDH-5 showed the strongest correlation with pimonidazole (r = 0.66, p = 0.002). MCT4 and GLUT-1 demonstrated a typical diffusion-limited hypoxic pattern and showed a high degree of colocalization. Both MCT4 and CAIX showed a higher expression in the primary tumor in node positive patients (p = 0.09 both). Colocalization and staining patterns of metabolic and hypoxia-related proteins provides valuable additional information over single protein analyses and can improve the understanding of their functions and environmental influences

A density functional theory study on the active center of Fe-only hydrogenase: characterization and electronic structure of the redox states.

Science.gov (United States)

Liu, Zhi-Pan; Hu, P

2002-05-08

We have carried out extensive density functional theory (DFT) calculations for possible redox states of the active center in Fe-only hydrogenases. The active center is modeled by [(H(CH(3))S)(CO)(CN(-))Fe(p)(mu-DTN)(mu-CO)Fe(d)(CO)(CN(-))(L)](z)() (z is the net charge in the complex; Fe(p)= the proximal Fe, Fe(d) = the distal Fe, DTN = (-SCH(2)NHCH(2)S-), L is the ligand that bonds with the Fe(d) at the trans position to the bridging CO). Structures of possible redox states are optimized, and CO stretching frequencies are calculated. By a detailed comparison of all the calculated structures and the vibrational frequencies with the available experimental data, we find that (i) the fully oxidized, inactive state is an Fe(II)-Fe(II) state with a hydroxyl (OH(-)) group bonded at the Fe(d), (ii) the oxidized, active state is an Fe(II)-Fe(I) complex which is consistent with the assignment of Cao and Hall (J. Am. Chem. Soc. 2001, 123, 3734), and (iii) the fully reduced state is a mixture with the major component being a protonated Fe(I)-Fe(I) complex and the other component being its self-arranged form, Fe(II)-Fe(II) hydride. Our calculations also show that the exogenous CO can strongly bond with the Fe(II)-Fe(I) species, but cannot bond with the Fe(I)-Fe(I) complex. This result is consistent with experiments that CO tends to inhibit the oxidized, active state, but not the fully reduced state. The electronic structures of all the redox states have been analyzed. It is found that a frontier orbital which is a mixing state between the e(g) of Fe and the 2 pi of the bridging CO plays a key role concerning the reactivity of Fe-only hydrogenases: (i) it is unoccupied in the fully oxidized, inactive state, half-occupied in the oxidized, active state, and fully occupied in the fully reduced state; (ii) the e(g)-2 pi orbital is a bonding state, and this is the key reason for stability of the low oxidation states, such as Fe(I)-Fe(I) complexes; and (iii) in the e(g)-2 pi orbital

Formation and Yield of Multi-Walled Carbon Nanotubes Synthesized via Chemical Vapour Deposition Routes Using Different Metal-Based Catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH

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Mohd Zobir Hussein

2014-11-01

Full Text Available Multi-walled carbon nanotubes (MWCNTs were prepared via chemical vapor deposition (CVD using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs. Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs.

Immobilization of hydrogenase on carbon nanotube polyelectrolytes as heterogeneous catalysts for electrocatalytic interconversion of protons and hydrogen

Energy Technology Data Exchange (ETDEWEB)

Liu, Jiang; Wu, Wen-Jie; Fang, Fang [Fudan University, Department of Chemistry (China); Zorin, Nikolay A. [Russian Academy of Sciences, Institute of Basic Biological Problems (Russian Federation); Chen, Meng; Qian, Dong-Jin, E-mail: djqian@fudan.edu.cn [Fudan University, Department of Chemistry (China)

2016-08-15

Immobilization of active enzymes on the surfaces of electrodes and nanomaterials is important in the fields of bioscience, and biotechnology. In this study, we investigated electrocatalytic properties of the interconversion of protons and hydrogen by means of hydrogenase (H{sub 2}ase)-functionalized carbon nanotube polyelectrolyte composites. Multiwalled carbon nanotube polyelectrolytes (MWNT-PEs) were synthesized through a diazonium and an addition reaction with poly(4-vinylpyridine) (P4VP), followed by another addition reaction with either methyl iodide (CH{sub 3}I) or N-methyl-N′-benzyl bromide bipyridinium (VBenBr) to produce MWNT-P4VPMe or MWNT-P4VPBenV polyelectrolytes, respectively. The MWNT-PE@H{sub 2}ase bio-nanocomposites were then prepared by means of MWNT-PEs as substrates to bind with H{sub 2}ase. The redox current density of the MWNT-PE@H{sub 2}ase-modified electrodes increased with a decrease in pH values of the Ar-saturated electrolyte solution owing to the catalytic reduction of protons (H{sub 2} production); further, it increased with the increasing pH values of the H{sub 2}-saturated solution owing to the catalytic oxidation of hydrogen. The reversible color change between blue-colored and colorless viologen (catalyzed by the MWNT-PE@H{sub 2}ase bio-nanocomposites) suggested that they may be developed as nano-biosensors for molecular H{sub 2}. The as-synthesized bio-nanocomposites showed strong long-term stability and high bioactivity.Graphical Abstract.

Computational NMR, IR/RAMAN calculations in sodium pravastatin: Investigation of the Self-Assembled Nanostructure of Pravastatin-LDH (Layered Double Hydroxides) Systems

Science.gov (United States)

Petersen, Philippe; Cunha, Vanessa; Gonçalves, Marcos; Petrilli, Helena; Constantino, Vera; Instituto de Física, Departamento de Física de Materiais e Mecânica Team; Instituto de Química, Departamento de Química Fundamental Team

2013-03-01

Layered double hydroxides (LDH) can be used as nanocontainers for immobilization of Pravastatin, in order to obtain suitable drug carriers. The material's structure and spectroscopic properties were analyzed by NMR, IR/RAMAN and supported by theoretical calculations. Density Functional Theory (DFT) calculations were performed using the Gaussian03 package. The geometry optimizations were performed considering the single crystal X-ray diffraction data of tert-octylamonium salt of Pravastatin. Tetramethylsilane (TMS), obtained with the same basis set, was used as reference for calculating the chemical shift of 13C. A scaling factor was used to compare theoretical and experimental harmonic vibrational frequencies. Through the NMR and IR/RAMAN spectra, we were able to make precise assignments of the NMR and IR/RAMAN of Sodium Pravastatin. We acknowledge support from CAPES, INEO and CNPQ.

Catalytic Properties of the Isolated Diaphorase Fragment of the NAD+-Reducing [NiFe]-Hydrogenase from Ralstonia eutropha

Science.gov (United States)

Lauterbach, Lars; Idris, Zulkifli; Vincent, Kylie A.; Lenz, Oliver

2011-01-01

The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha H16 catalyzes the H2-driven reduction of NAD+, as well as reverse electron transfer from NADH to H+, in the presence of O2. It comprises six subunits, HoxHYFUI2, and incorporates a [NiFe] H+/H2 cycling catalytic centre, two non-covalently bound flavin mononucleotide (FMN) groups and an iron-sulfur cluster relay for electron transfer. This study provides the first characterization of the diaphorase sub-complex made up of HoxF and HoxU. Sequence comparisons with the closely related peripheral subunits of Complex I in combination with UV/Vis spectroscopy and the quantification of the metal and FMN content revealed that HoxFU accommodates a [2Fe2S] cluster, FMN and a series of [4Fe4S] clusters. Protein film electrochemistry (PFE) experiments show clear electrocatalytic activity for both NAD+ reduction and NADH oxidation with minimal overpotential relative to the potential of the NAD+/NADH couple. Michaelis-Menten constants of 56 µM and 197 µM were determined for NADH and NAD+, respectively. Catalysis in both directions is product inhibited with K I values of around 0.2 mM. In PFE experiments, the electrocatalytic current was unaffected by O2, however in aerobic solution assays, a moderate superoxide production rate of 54 nmol per mg of protein was observed, meaning that the formation of reactive oxygen species (ROS) observed for the native SH can be attributed mainly to HoxFU. The results are discussed in terms of their implications for aerobic functioning of the SH and possible control mechanism for the direction of catalysis. PMID:22016788

Hydrogen from Water in a Novel Recombinant Cyanobacterial System

Energy Technology Data Exchange (ETDEWEB)

Weyman, Philip D [J. Craig Venter Institute; Smith, Hamillton O.

2014-12-03

Photobiological processes are attractive routes to renewable H2 production. With the input of solar energy, photosynthetic microbes such as cyanobacteria and green algae carry out oxygenic photosynthesis, using sunlight energy to extract protons and high energy electrons from water. These protons and high energy electrons can be fed to a hydrogenase system yielding H2. However, most hydrogen-evolving hydrogenases are inhibited by O2, which is an inherent byproduct of oxygenic photosynthesis. The rate of H2 production is thus limited. Certain photosynthetic bacteria are reported to have an O2-tolerant evolving hydrogenase, yet these microbes do not split water, and require other more expensive feedstocks. To overcome these difficulties, the goal of this work has been to construct novel microbial hybrids by genetically transferring O2-tolerant hydrogenases from other bacteria into a class of photosynthetic bacteria called cyanobacteria. These hybrid organisms will use the photosynthetic machinery of the cyanobacterial hosts to perform the water-oxidation reaction with the input of solar energy, and couple the resulting protons and high energy electrons to the O2-tolerant bacterial hydrogenase, all within the same microbe (Fig. 1). The ultimate goal of this work has been to overcome the sensitivity of the hydrogenase enzyme to O2 and address one of the key technological hurdles to cost-effective photobiological H2 production which currently limits the production of hydrogen in algal systems. In pursuit of this goal, work on this project has successfully completed many subtasks leading to a greatly increased understanding of the complicated [NiFe]-hydrogenase enzymes. At the beginning of this project, [NiFe] hydrogenases had never been successfully moved across wide species barriers and had never been heterologously expressed in cyanobacteria. Furthermore, the idea that whole, functional genes could be extracted from complicated, mixed-sequence meta-genomes was not

CO-Bridged H-Cluster Intermediates in the Catalytic Mechanism of [FeFe]-Hydrogenase CaI.

Science.gov (United States)

Ratzloff, Michael W; Artz, Jacob H; Mulder, David W; Collins, Reuben T; Furtak, Thomas E; King, Paul W

2018-06-20

The [FeFe]-hydrogenases ([FeFe] H 2 ases) catalyze reversible H 2 activation at the H-cluster, which is composed of a [4Fe-4S] H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe] H ) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H 2 bond activation have been proposed. We have examined this question in the [FeFe] H 2 ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions. One-electron reduction of H ox led to formation of H red H + ([4Fe-4S] H 2+ -Fe I -Fe I ) and H red ' ([4Fe-4S] H 1+ -Fe II -Fe I ), with both states characterized by low frequency μ-CO IR modes consistent with a fully bridged [2Fe] H . Similar μ-CO IR modes were also identified for H red H + of the [FeFe] H 2 ase from Chlamydomonas reinhardtii (CrHydA1). The CaI proton-transfer variant C298S showed enrichment of an H/D isotope-sensitive μ-CO mode, a component of the hydride bound H-cluster IR signal, H hyd . Equilibrating CaI with increasing amounts of NaDT, and probed at cryogenic temperatures, showed H red H + was converted to H hyd . Over an increasing temperature range from 10 to 260 K catalytic turnover led to loss of H hyd and appearance of H ox , consistent with enzymatic turnover and H 2 formation. The results show for CaI that the μ-CO of [2Fe] H remains bridging for all of the "H red " states and that H red H + is on pathway to H hyd and H 2 evolution in the catalytic mechanism. These results provide a blueprint for designing small molecule catalytic analogs.

Methanogenesis and methane genes

International Nuclear Information System (INIS)

Reeve, J.N.; Shref, B.A.

1991-01-01

An overview of the pathways leading to methane biosynthesis is presented. The steps investigated to date by gene cloning and DNA sequencing procedures are identified and discussed. The primary structures of component C of methyl coenzyme M reductase encoded by mcr operons in different methanogens are compared. Experiments to detect the primary structure of the genes encoding F420 reducing hydrogenase (frhABG) and methyl hydrogen reducing hydrogenase (mvhDGA) in methanobacterium thermoautotrophicum strain H are compared with each other and with eubacterial hydrogenase encoding genes. A biotechnological use for hydrogenases from hypermorphillic archaebacteria is suggested. (author)

Nickel accumulation and storage in bradyrhizobium japonicum

International Nuclear Information System (INIS)

Maier, R.J.; Pihl, T.D.; Stults, L.; Sray, W.

1990-01-01

Hydrogenase-depressed (chemolithotrophic growth conditions) and heterotrophically grown cultures of Bradyrhizobium japonicum accumulated nickel about equally over a 3-h period. Both types of cultures accumulated nickel primarily in a form that was not exchangeable with NiCl 2 , and they accumulated much more Ni than would be needed for the Ni-containing hydrogenase. The nickel accumulated by heterotrophically incubated cultures could later be mobilized to allow active hydrogenase synthesis during derepression in the absence of nickel, while cells both grown with Ni and the derepressed without nickel had low hydrogenase activities. The level of activity in cells grown with Ni and then derepressed without nickel was about the same as that in cultures derepressed in the presence of nickel. The Ni accumulated by heterotrophically grown cultures was associated principally with soluble proteins rather than particulate material, and this Ni was not lost upon dialyzing an extract containing the soluble proteins against either Ni-containing or EDTA-containing buffer. However, this Ni was lost upon pronase or low pH treatments. The soluble Ni-binding proteins were partially purified by gel filtration and DEAE chromatography. They were not antigenically related to hydrogenase peptides. Much of the 63 Ni eluted as a single peak of 48 kilodaltons. Experiments involving immunuprecipitation of 63 Ni-containing hydrogenase suggested that the stored source of Ni in heterotrophic cultures that could later be mobilized into hydrogenase resided in the nonexchangeable Ni-containing fraction rather than in loosely bound or ionic forms

Single-Amino Acid Modifications Reveal Additional Controls on the Proton Pathway of [FeFe]-Hydrogenase

Energy Technology Data Exchange (ETDEWEB)

Cornish, Adam J.; Ginovska, Bojana; Thelen, Adam; da Silva, Julio C. S.; Soares, Thereza A.; Raugei, Simone; Dupuis, Michel; Shaw, Wendy J.; Hegg, Eric L.

2016-06-07

The proton pathway of [FeFe]-hydrogenase is essential for enzymatic H2 production and oxidation and is composed of four residues and a modeled water molecule. Recently, a computational analysis of this pathway revealed that the solvent-exposed residue of the pathway (Glu282) could form hydrogen bonds to two residues outside of the pathway (Arg286 and Ser320), implicating that these residues could function in regulating proton transfer. Substituting Arg286 with leucine eliminates hydrogen bonding with Glu282 and results in a 2.5-fold enhancement in H2 production activity, suggesting that Arg286 serves an important role in controlling the rate of proton delivery. In contrast, substitution of Ser320 with alanine reduces the rate approximately 5-fold, implying that it either acts as a member of the pathway or influences Glu282 to enable proton transfer. Interestingly, QM/MM and molecular dynamics calculations indicate that Ser320 does not play an electronic or structural role. QM calculations also estimate that including Ser320 in the pathway does not significantly change the barrier to proton movement, providing further support for its role as a member of the proton pathway. While further studies are needed to quantify the role of Ser320, collectively, these data provide evidence that the enzyme scaffold plays a significant role in modulating the activity of the enzyme, demonstrating that the rate of intraprotein proton transfer can be accelerated, particularly in a non-biological context. This work was supported by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science, DE-FC02-07ER64494). In addition, support from the DOE Office of Science Early Career Research Program through the Office of Basic Energy Sciences (WJS, BGP, SR) is gratefully acknowledged. Computational resources were provided at W. R. Wiley Environmental Molecular Science Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy’s Office of

The Use of Aquatic Plants in Wastewater Treatment: A Literature Review.

Science.gov (United States)

1992-12-01

ranunculoides , H. spp.) are not normally free floating plants. They are normally rooted into the substrate in shallow water, with their leaves and stems...Most of the approximately 100 species are found in the temperate zones, but H. ranunculoides is found as far north as Pennsylvania and 14 Y,2 Figure...2-2 Water Lettuce (Hyda stradtioes) Figure 2-3 Pennywort ( Hydrocotyle spp.) 15 Delaware (Correl and Johnston, 1970). They are also of interest because

Hydrogen-producing microflora and Fe-Fe hydrogenase diversities in seaweed bed associated with marine hot springs of Kalianda, Indonesia.

Science.gov (United States)

Xu, Shou-Ying; He, Pei-Qing; Dewi, Seswita-Zilda; Zhang, Xue-Lei; Ekowati, Chasanah; Liu, Tong-Jun; Huang, Xiao-Hang

2013-05-01

Microbial fermentation is a promising technology for hydrogen (H(2)) production. H(2) producers in marine geothermal environments are thermophilic and halotolerant. However, no one has surveyed an environment specifically for thermophilic bacteria that produce H(2) through Fe-Fe hydrogenases (H(2)ase). Using heterotrophic medium, several microflora from a seaweed bed associated with marine hot springs were enriched and analyzed for H(2) production. A H(2)-producing microflora was obtained from Sargassum sp., 16S rRNA genes and Fe-Fe H(2)ase diversities of this enrichment were also analyzed. Based on 16S rRNA genes analysis, 10 phylotypes were found in the H(2)-producing microflora showing 90.0-99.5 % identities to known species, and belonged to Clostridia, Gammaproteobacteria, and Bacillales. Clostridia were the most abundant group, and three Clostridia phylotypes were most related to known H(2) producers such as Anaerovorax odorimutans (94.0 % identity), Clostridium papyrosolvens (98.4 % identity), and Clostridium tepidiprofundi (93.1 % identity). For Fe-Fe H(2)ases, seven phylotypes were obtained, showing 63-97 % identities to known Fe-Fe H(2)ases, and fell into four distinct clusters. Phylotypes HW55-3 and HM55-1 belonged to thermophilic and salt-tolerant H(2)-producing Clostridia, Halothermothrix orenii-like Fe-Fe H(2)ases (80 % identity), and cellulolytic H(2)-producing Clostridia, C. papyrosolvens-like Fe-Fe H(2)ases (97 % identity), respectively. The results of both 16S rRNA genes and Fe-Fe H(2)ases surveys suggested that the thermophilic and halotolerant H(2)-producing microflora in seaweed bed of hot spring area represented previously unknown H(2) producers, and have potential application for H(2) production.

NCBI nr-aa BLAST: CBRC-AGAM-02-0168 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-AGAM-02-0168 ref|YP_001226076.1| Hydrogenase/urease accessory protein [Synecho...coccus sp. WH 7803] emb|CAK24779.1| Hydrogenase/urease accessory protein [Synechococcus sp. WH 7803] YP_001226076.1 1.0 28% ...

Engineering Synechocystis PCC6803 for hydrogen production: influence on the tolerance to oxidative and sugar stresses.

Directory of Open Access Journals (Sweden)

Marcia Ortega-Ramos

Full Text Available In the prospect of engineering cyanobacteria for the biological photoproduction of hydrogen, we have studied the hydrogen production machine in the model unicellular strain Synechocystis PCC6803 through gene deletion, and overexpression (constitutive or controlled by the growth temperature. We demonstrate that the hydrogenase-encoding hoxEFUYH operon is dispensable to standard photoautotrophic growth in absence of stress, and it operates in cell defense against oxidative (H₂O₂ and sugar (glucose and glycerol stresses. Furthermore, we showed that the simultaneous over-production of the proteins HoxEFUYH and HypABCDE (assembly of hydrogenase, combined to an increase in nickel availability, led to an approximately 20-fold increase in the level of active hydrogenase. These novel results and mutants have major implications for those interested in hydrogenase, hydrogen production and redox metabolism, and their connections with environmental conditions.

Transcript analysis of the extended hyp-operon in the cyanobacteria Nostoc sp. strain PCC 7120 and Nostoc punctiforme ATCC 29133

Science.gov (United States)

2011-01-01

Background Cyanobacteria harbor two [NiFe]-type hydrogenases consisting of a large and a small subunit, the Hup- and Hox-hydrogenase, respectively. Insertion of ligands and correct folding of nickel-iron hydrogenases require assistance of accessory maturation proteins (encoded by the hyp-genes). The intergenic region between the structural genes encoding the uptake hydrogenase (hupSL) and the accessory maturation proteins (hyp genes) in the cyanobacteria Nostoc PCC 7120 and N. punctiforme were analysed using molecular methods. Findings The five ORFs, located in between the uptake hydrogenase structural genes and the hyp-genes, can form a transcript with the hyp-genes. An identical genomic localization of these ORFs are found in other filamentous, N2-fixing cyanobacterial strains. In N. punctiforme and Nostoc PCC 7120 the ORFs upstream of the hyp-genes showed similar transcript level profiles as hupS (hydrogenase structural gene), nifD (nitrogenase structural gene), hypC and hypF (accessory hydrogenase maturation genes) after nitrogen depletion. In silico analyzes showed that these ORFs in N. punctiforme harbor the same conserved regions as their homologues in Nostoc PCC 7120 and that they, like their homologues in Nostoc PCC 7120, can be transcribed together with the hyp-genes forming a larger extended hyp-operon. DNA binding studies showed interactions of the transcriptional regulators CalA and CalB to the promoter regions of the extended hyp-operon in N. punctiforme and Nostoc PCC 7120. Conclusions The five ORFs upstream of the hyp-genes in several filamentous N2-fixing cyanobacteria have an identical genomic localization, in between the genes encoding the uptake hydrogenase and the maturation protein genes. In N. punctiforme and Nostoc PCC 7120 they are transcribed as one operon and may form transcripts together with the hyp-genes. The expression pattern of the five ORFs within the extended hyp-operon in both Nostoc punctiforme and Nostoc PCC 7120 is similar to

NCBI nr-aa BLAST: CBRC-XTRO-01-2348 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-XTRO-01-2348 ref|YP_594815.1| hydrogenase-1 small subunit [Lawsonia intracellu...laris PHE/MN1-00] emb|CAJ54493.1| hydrogenase-1 small subunit [Lawsonia intracellularis PHE/MN1-00] YP_594815.1 6.0 27% ...

The Role of Hydrogen for Sulfurimonas denitrificans’ Metabolism

Science.gov (United States)

Han, Yuchen; Perner, Mirjam

2014-01-01

Sulfurimonas denitrificans was originally isolated from coastal marine sediments. It can grow with thiosulfate and nitrate or sulfide and oxygen. Recently sequencing of its genome revealed that it encodes periplasmic and cytoplasmic [NiFe]-hydrogenases but the role of hydrogen for its metabolism has remained unknown. We show the first experimental evidence that S. denitrificans can indeed express a functional hydrogen uptake active hydrogenase and can grow on hydrogen. In fact, under the provided conditions it grew faster and denser on hydrogen than on thiosulfate alone and even grew with hydrogen in the absence of reduced sulfur compounds. In our experiments, at the time points tested, the hydrogen uptake activity appeared to be related to the periplasmic hydrogenase and not to the cytoplasmic hydrogenase. Our data suggest that under the provided conditions S. denitrificans can grow more efficiently with hydrogen than with thiosulfate. PMID:25170905

Sudden onset of facial edema and serum LDH elevation after radiation therapy for malignant lymphoma of the left parotid gland. A case report

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Gen; Ogo, Etuyo; Toda, Yukihiro; Suefuji, Hiroaki; Hayabuchi, Naofumi [Kurume Univ., Fukuoka (Japan). School of Medicine

2001-12-01

A report of a 48 year-old male with non-Hodgkin's lymphoma of the left parotid gland (clinical stage I EA, follicular medium-sized B cell type) is presented. He was solely treated with 30 Gy of radiation to the whole neck region, bilateral paraclavicular region and the left axilla, and 10.6 Gy boost was given to the primary lesion. Five months later, facial edema and serum LDH elevation developed suddenly. Relapse of the malignant lymphoma was suspected, but a whole body CT scan failed to show this. On the contrary, the CT scan showed a diffuse hypoattenuated area of the thyroid gland. In addition to positive antibodies, i.e, antithyroglobulin and antimicrosomal antibodies, total cholesterol and other serum markers also suggested hypofunction of the thyroid due to acute exacerbation of chronic thyroiditis. Immediately after hormone-replacement therapy, his symptoms disappeared and the abnormal serum data improved. Although the relationship between chronic thyroiditis and radiation injury has not been clearly demonstrated, it seems necessary to evaluate thyroid function before radiotherapy for head and neck tumors. Patients with chronic thyroiditis should be followed carefully after radiotherapy. (author)

NCBI nr-aa BLAST: CBRC-DNOV-01-2127 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-DNOV-01-2127 ref|YP_712620.1| [NiFe] hydrogenase maturation protein HypF [Fran...kia alni ACN14a] emb|CAJ61046.1| [NiFe] hydrogenase maturation protein HypF [Frankia alni ACN14a] YP_712620.1 0.81 32% ...

Cloning and knockout of formate hydrogen lyase and H{sub 2}-uptake hydrogenase genes in Enterobacter aerogenes for enhanced hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Zhao, Hongxin; Ma, Kun; Lu, Yuan; Zhang, Chong; Wang, Liyan; Xing, Xin-Hui [Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Tsinghua Yuan, Beijing 100084 (China)

2009-01-15

A 5431-bp DNA fragment partially encoding the formate hydrogen lyase (FHL) gene cluster hycABCDE was isolated and identified from Enterobacter aerogenes IAM1183 chromosomal DNA. All the five putative gene products showed a high degree of homology to the reported bacterial FHL proteins. The gene hycA, encoding the FHL repressor protein, and hybO, encoding the small subunit of the uptake hydrogenase, were targeted for genetic knockout for improving the hydrogen production. The pYM-Red recombination system was adopted to form insertional mutations in the E. aerogenes genome, thereby creating mutant strains of IAM1183-A ({delta} hycA), IAM1183-O ({delta} hybO), and IAM1183-AO ({delta} hycA/ {delta} hybO double knockout). The hydrogen production experiments with these mutants showed that the maximum specific hydrogen productivities of IAM1183-A, IAM1183-O, and IAM1183-AO were 2879.466 {+-} 38.59, 2747.203 {+-} 13.25 and 3372.019 {+-} 4.39 (ml h{sup -1} g{sup -1}dry cell weight), respectively, higher than that of the wild strain (2321.861 {+-} 15.34 ml h{sup -1} g{sup -1}dry cell weight). The total H{sub 2} yields by the three mutants IAM1183-A, IAM1183-O and IAM1183-AO were 0.73, 0.78, and 0.83 mol-H{sub 2}/mol glucose, respectively, while the wild-type IAM1183 was only 0.65 mol-H{sub 2}/mol glucose. The metabolites of the mutants including acetate, ethanol, 2,3-butanediol and succinate were all increased compared with that of the wild type, implying the changed metabolic flux by the mutation. In the fermentor cultivation with IAM1183 {delta} hycA/ {delta} hybO, the total hydrogen volume after 16 h cultivation reached 4.4 L, while that for the wild type was only 2.9 L. (author)

Respiratory hydrogen use by Salmonella enterica serovar Typhimurium is essential for virulence.

Science.gov (United States)

Maier, R J; Olczak, A; Maier, S; Soni, S; Gunn, J

2004-11-01

Based on available annotated gene sequence information, the enteric pathogen salmonella, like other enteric bacteria, contains three putative membrane-associated H2-using hydrogenase enzymes. These enzymes split molecular H2, releasing low-potential electrons that are used to reduce quinone or heme-containing components of the respiratory chain. Here we show that each of the three distinct membrane-associated hydrogenases of Salmonella enterica serovar Typhimurium is coupled to a respiratory pathway that uses oxygen as the terminal electron acceptor. Cells grown in a blood-based medium expressed four times the amount of hydrogenase (H2 oxidation) activity that cells grown on Luria Bertani medium did. Cells suspended in phosphate-buffered saline consumed 2 mol of H2 per mol of O2 used in the H2-O2 respiratory pathway, and the activity was inhibited by the respiration inhibitor cyanide. Molecular hydrogen levels averaging over 40 microM were measured in organs (i.e., livers and spleens) of live mice, and levels within the intestinal tract (the presumed origin of the gas) were four times greater than this. The half-saturation affinity of S. enterica serovar Typhimurium for H2 is only 2.1 microM, so it is expected that H2-utilizing hydrogenase enzymes are saturated with the reducing substrate in vivo. All three hydrogenase enzymes contribute to the virulence of the bacterium in a typhoid fever-mouse model, based on results from strains with mutations in each of the three hydrogenase genes. The introduced mutations are nonpolar, and growth of the mutant strains was like that of the parent strain. The combined removal of all three hydrogenases resulted in a strain that is avirulent and (in contrast to the parent strain) one that is unable to invade liver or spleen tissue. The introduction of one of the hydrogenase genes into the triple mutant strain on a low-copy-number plasmid resulted in a strain that was able to both oxidize H2 and cause morbidity in mice within 11

Dark hydrogen production in nitrogen atmosphere - An approach for sustainability by marine cyanobacterium Leptolyngbya valderiana BDU 20041

Energy Technology Data Exchange (ETDEWEB)

Prabaharan, D.; Arun Kumar, D.; Uma, L.; Subramanian, G. [National Facility for Marine Cyanobacteria (Sponsored by DBT, Govt. of India), Department of Marine Biotechnology, Bharathidasan University, Tiruchirapalli 620 024 (India)

2010-10-15

Biological hydrogen production is an ideal system for three main reasons i) forms a renewable energy source, ii) gives clean fuel and iii) serves as a good supplement to oil reserves. The major challenges faced in biological hydrogen production are the presence of uptake hydrogenase and lack of sustainability in the cyanobacterial hydrogen production system. Three different marine cyanobacterial species viz. Leptolyngbya valderiana BDU 20041, Dichothrix baueriana BDU 40481 and Nostoc calcicola BDU 40302 were studied for their potential use in hydrogen production. Among these, L. valderiana BDU 20041, was found to produce hydrogen even in 100% nitrogen atmosphere which was 85% of the hydrogen produced in argon atmosphere. This is the first report of such a high rate of production of hydrogen in a nitrogen atmosphere by a cyanobacterium, which makes it possible to develop sustained hydrogen production systems. L. valderiana BDU 20041, a dark hydrogen producer uses the reductant essentially supplied by the respiratory pathway for hydrogen production. Using inhibitors, this organism was found to produce hydrogen due to the activities of both nitrogenase and bidirectional hydrogenase, while it had no 'uptake' hydrogenase activity. The other two organisms though had low levels of bidirectional hydrogenase, possessed considerable 'uptake' hydrogenase activity and hence could not release much hydrogen either in argon or nitrogen atmosphere. (author)

Enzymatic recovery of platinum (IV) from industrial wastewater using ...

African Journals Online (AJOL)

highest hydrogen-dependent platinum (IV) reducing activity in the presence of hydrogenase and its physiological electron carrier, cytochrome c3. When the purified hydrogenase enzyme (with and without cytochrome c3) was used with the industrial effluent, containing 7.9 mg.l-1 platinum, only 10 – 15% recovery was noted ...

Enzymatic recovery of platinum (IV) from industrial wastewater using ...

African Journals Online (AJOL)

SERVER

2008-04-17

Apr 17, 2008 ... A hydrogenase from sulphate reducing consortium was purified by a ... diation. The present work reports on the use of SRB cells from the resting .... hydrogenase fraction had a half life of 35 minutes (t1/2 = 35). ... balance (Hughes and Poole, 1997). ... an enzyme efficiency (Kcat) (turnover number) of 3.6 s-1.

Bio-Prospecting for Improved Hydrogen-Producing Organisms

Science.gov (United States)

2011-06-01

including soil, sediment, seawater, thermophilic compost, and geothermal sites. Cyanobacterial production of hydrogen and oxygen in natural habitats...Berelson and Corsetti at USC-, experiments were conducted to analyze the hydrogenase enzymes and microbial community of a novel cyanobacterially...another. Future work should involve rate and flux experiments, further investigation of the hydrogenase enzymes involved and follow up work with D:H ratio

Contributory roles of two l-lactate dehydrogenases for l-lactic acid production in thermotolerant Bacillus coagulans.

Science.gov (United States)

Sun, Lifan; Zhang, Caili; Lyu, Pengcheng; Wang, Yanping; Wang, Limin; Yu, Bo

2016-11-25

Thermotolerant Bacillus coagulans is considered to be a more promising producer for bio-chemicals, due to its capacity to withstand harsh conditions. Two L-lactate dehydrogenase (LDH) encoding genes (ldhL1 and ldhL2) and one D-LDH encoding gene (ldhD) were annotated from the B. coagulans DSM1 genome. Transcriptional analysis revealed that the expression of ldhL2 was undetectable while the ldhL1 transcription level was much higher than that of ldhD at all growth phases. Deletion of the ldhL2 gene revealed no difference in fermentation profile compared to the wild-type strain, while ldhL1 single deletion or ldhL1ldhL2 double deletion completely blocked L-lactic acid production. Complementation of ldhL1 in the above knockout strains restored fermentation profiles to those observed in the wild-type strain. This study demonstrates ldhL1 is crucial for L-lactic acid production and NADH balance in B. coagulans DSM1 and lays the fundamental for engineering the thermotolerant B. coagulans strain as a platform chemicals producer.

Use of molecular hydrogen as an energy substrate by human pathogenic bacteria.

Science.gov (United States)

Maier, R J

2005-02-01

Molecular hydrogen is produced as a fermentation by-product in the large intestine of animals and its production can be correlated with the digestibility of the carbohydrates consumed. Pathogenic Helicobacter species (Helicobacter pylori and H. hepaticus) have the ability to use H(2) through a respiratory hydrogenase, and it was demonstrated that the gas is present in the tissues colonized by these pathogens (the stomach and the liver respectively of live animals). Mutant strains of H. pylori unable to use H(2) are deficient in colonizing mice compared with the parent strain. On the basis of available annotated gene sequence information, the enteric pathogen Salmonella, like other enteric bacteria, contains three putative membrane-associated H(2)-using hydrogenase enzymes. From the analysis of gene-targeted mutants it is concluded that each of the three membrane-bound hydrogenases of Salmonella enterica serovar Typhimurium are coupled with an H(2)-oxidizing respiratory pathway. From microelectrode probe measurements on live mice, H(2) could be detected at approx. 50 muM levels within the tissues (liver and spleen), which are colonized by Salmonella. The half-saturation affinity of whole cells of these pathogens for H(2) is much less than this, so it is expected that the (H(2)-utilizing) hydrogenase enzymes be saturated with the reducing substrate in vivo. All three enteric NiFe hydrogenase enzymes contribute to virulence of the bacterium in a typhoid fever-mouse model, and the combined removal of all three hydrogenases resulted in a strain that is avirulent and (in contrast with the parent strain) one that is not able to pass the intestinal tract to invade liver or spleen tissue. It is proposed that H(2) utilization and specifically its oxidation, coupled with a respiratory pathway, is required for energy production to permit growth and maintain efficient virulence of a number of pathogenic bacteria during infection of animals. These would be expected to include

Transcription of the extended hyp-operon in Nostoc sp. strain PCC 7120

Science.gov (United States)

Agervald, Åsa; Stensjö, Karin; Holmqvist, Marie; Lindblad, Peter

2008-01-01

Background The maturation of hydrogenases into active enzymes is a complex process and e.g. a correctly assembled active site requires the involvement of at least seven proteins, encoded by hypABCDEF and a hydrogenase specific protease, encoded either by hupW or hoxW. The N2-fixing cyanobacterium Nostoc sp. strain PCC 7120 may contain both an uptake and a bidirectional hydrogenase. The present study addresses the presence and expression of hyp-genes in Nostoc sp. strain PCC 7120. Results RT-PCRs demonstrated that the six hyp-genes together with one ORF may be transcribed as a single operon. Transcriptional start points (TSPs) were identified 280 bp upstream from hypF and 445 bp upstream of hypC, respectively, demonstrating the existence of several transcripts. In addition, five upstream ORFs located in between hupSL, encoding the small and large subunits of the uptake hydrogenase, and the hyp-operon, and two downstream ORFs from the hyp-genes were shown to be part of the same transcript unit. A third TSP was identified 45 bp upstream of asr0689, the first of five ORFs in this operon. The ORFs are annotated as encoding unknown proteins, with the exception of alr0692 which is identified as a NifU-like protein. Orthologues of the four ORFs asr0689-alr0692, with a highly conserved genomic arrangement positioned between hupSL, and the hyp genes are found in several other N2-fixing cyanobacteria, but are absent in non N2-fixing cyanobacteria with only the bidirectional hydrogenase. Short conserved sequences were found in six intergenic regions of the extended hyp-operon, appearing between 11 and 79 times in the genome. Conclusion This study demonstrated that five ORFs upstream of the hyp-gene cluster are co-transcribed with the hyp-genes, and identified three TSPs in the extended hyp-gene cluster in Nostoc sp. strain PCC 7120. This may indicate a function related to the assembly of a functional uptake hydrogenase, hypothetically in the assembly of the small subunit of

Biomimetic hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Krassen, Henning

2009-05-15

Hydrogenases catalyze the reduction of protons to molecular hydrogen with outstanding efficiency. An electrode surface which is covered with active hydrogenase molecules becomes a promising alternative to platinum for electrochemical hydrogen production. To immobilize the hydrogenase on the electrode, the gold surface was modified by heterobifunctional molecules. A thiol headgroup on one side allowed the binding to the gold surface and the formation of a self-assembled monolayer. The other side of the molecules provided a surface with a high affinity for the hydrogenase CrHydA1 from Chlamydomonas reinhardtii. With methylviologen as a soluble energy carrier, electrons were transferred from carboxy-terminated electrodes to CrHydA1 and conducted to the active site (H-cluster), where they reduce protons to molecular hydrogen. A combined approach of surface-enhanced infrared absorption spectroscopy, gas chromatography, and surface plasmon resonance allowed quantifying the hydrogen production on a molecular level. Hydrogen was produced with a rate of 85 mol H{sub 2} min{sup -1} mol{sup -1}. On a 1'- benzyl-4,4'-bipyridinum (BBP)-terminated surface, the electrons were mediated by the monolayer and no soluble electron carrier was necessary to achieve a comparable hydrogen production rate (approximately 50% of the former system). The hydrogen evolution potential was determined to be -335 mV for the BBP-bound hydrogenase and -290 mV for the hydrogenase which was immobilized on a carboxy-terminated mercaptopropionic acid SAM. Therefore, both systems significantly reduce the hydrogen production overpotential and allow electrochemical hydrogen production at an energy level which is close to the commercially applied platinum electrodes (hydrogen evolution potential of -270 mV). In order to couple hydrogen production and photosynthesis, photosystem I (PS1) from Synechocystis PCC 6803 and membrane-bound hydrogenase (MBH) from Ralstonia eutropha were bound to each other

Escherichia coli K-12 survives anaerobic exposure at pH 2 without RpoS, Gad, or hydrogenases, but shows sensitivity to autoclaved broth products.

Directory of Open Access Journals (Sweden)

Daniel P Riggins

Full Text Available Escherichia coli and other enteric bacteria survive exposure to extreme acid (pH 2 or lower in gastric fluid. Aerated cultures survive via regulons expressing glutamate decarboxylase (Gad, activated by RpoS, cyclopropane fatty acid synthase (Cfa and others. But extreme-acid survival is rarely tested under low oxygen, a condition found in the stomach and the intestinal tract. We observed survival of E. coli K-12 W3110 at pH 1.2-pH 2.0, conducting all manipulations (overnight culture at pH 5.5, extreme-acid exposure, dilution and plating in a glove box excluding oxygen (10% H2, 5% CO2, balance N2. With dissolved O2 concentrations maintained below 6 µM, survival at pH 2 required Cfa but did not require GadC, RpoS, or hydrogenases. Extreme-acid survival in broth (containing tryptone and yeast extract was diminished in media that had been autoclaved compared to media that had been filtered. The effect of autoclaved media on extreme-acid survival was most pronounced when oxygen was excluded. Exposure to H2O2 during extreme-acid treatment increased the death rate slightly for W3110 and to a greater extent for the rpoS deletion strain. Survival at pH 2 was increased in strains lacking the anaerobic regulator fnr. During anaerobic growth at pH 5.5, strains deleted for fnr showed enhanced transcription of acid-survival genes gadB, cfa, and hdeA, as well as catalase (katE. We show that E. coli cultured under oxygen exclusion (<6 µM O2 requires mechanisms different from those of aerated cultures. Extreme acid survival is more sensitive to autoclave products under oxygen exclusion.

Renewable Bio-Solar Hydrogen Production From Robust Oxygenic Phototrophs: The Second Generation

Science.gov (United States)

2014-07-14

adds a layer of complexity due to oxygen’s natural prevalence in air. Furthermore, oxygenic photosynthesis, the most effective photosynthesis, is...between the oxic and anoxic layers as well as the anaerobic water and benthic layers . (c) We have tested the hypothesis that sequence variations...both hydrogenase and urease in Helicobacter pylori, Mol Microbiol, 39 (2001) 176-182. [199] L. Forzi, R.G. Sawers, Maturation of [NiFe]-hydrogenases

Preparation of Tween 80-Zn/Al-Levodopa-Layered Double Hydroxides Nanocomposite for Drug Delivery System

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Aminu Umar Kura

2014-01-01

Full Text Available We incorporated anti-Parkinsonian drug, levodopa (dopa, in Zn/Al-LDH by coprecipitation method to form dopa-LDH nanocomposite. Further coating of Tween-80 on the external surfaces of dopa-LDH nanocomposite was achieved through the oxygen of C=O group of Tween-80 with the layer of dopa-LDH nanocomposite. The final product is called Tween-dopa-LDH nanocomposite. The X-ray diffraction indicates that the Tween-dopa-LDH nanocomposite was formed by aggregation structure. From the TGA data, the Tween-80 loading on the surface of LDH and dopa-LDH was 8.6 and 7.4%, respectively. The effect of coating process on the dopa release from Tween-dopa-LDH nanocomposite was also studied. The release from Tween-dopa-LDH nanocomposite shows slower release compared to the release of the drug from dopa-LDH nanocomposite as done previously in our study, presumably due to the retarding shielding effect. The cell viability study using PC12 showed improved viability with Tween-80 coating on dopa-LDH nanocomposite as studied by mitochondrial dehydrogenase activity (MTT assay.

Biological H{sub 2} from syngas and from H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Weaver, P.; Maness, P.C.; Markov, S.; Martin, S. [National Renewable Energy Lab., Golden, CO (United States)

1996-10-01

The two stand-alone objectives of the research are to economically produce neat H{sub 2} in the near term from biomass (thermally gasified to syngas) and in the mid term from H{sub 2}O using cyanobacteria or algae with an oxygen-tolerant bacterial hydrogenase. Photosynthetic bacteria have four different terminal enzymes that mediate their H{sub 2} metabolisms-nitrogenase, uptake hydrogenase, fermentative hydrogenase, and carbon monoxide-linked hydrogenase. Each has been microbiologically and biochemically examined for their potential to specifically generate H{sub 2} in large-scale processes. Based on measurements of maximal activities, stabilities, energy requirements, equilibria, and partial pressures of the H{sub 2} producing reactions, the CO-linked hydrogenase is easily the most suited for practical applications. The enzyme mediates H{sub 2} production from CO at rates up to 1.5 mmol/min/g cell dry weight at near ambient temperature and pressure. Hydrogen can be produced and evolved at linear rates up to at least 2 atmospheres of partial pressure (100% CO). The rate-limiting step with high cell density suspensions is the mass transfer of CO into the aqueous phase. Bioreactor designs have been examined which enhance the mass transfer. Hollow-fiber bioreactors with bacterial cells immobilized on the fiber surfaces evolve H{sub 2} at ambient pressure at rates of about 0.3-0.7 mmol/min/g cdw. One such reactor has been producing H{sub 2} from CO continuously for 9 months with only occasional changes of liquid medium. A trickle-filter reactor with bacteria immobilized on beads removed from a bulk water phase and a pumped-bubble coil reactor with bacteria in suspension are also being examined.

Urinary Lactate Dehydrogenase Activity and Its Isozyme Patterns in Kawasaki Disease

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Yoichi Kawamura

2017-01-01

Full Text Available Abnormal urinary findings, such as sterile pyuria, proteinuria, and microscopic hematuria, are often seen in the acute phase of Kawasaki disease (KD. We investigated the potential significance of urinary lactate dehydrogenase (U-LDH activity and its isozyme patterns in KD. Total U-LDH activity and its isozymes (U-LDH1-5 levels were compared among 120 patients with KD, 18 patients with viral infection (VI, and 43 patients with upper urinary tract infection (UTI and additionally compared between intravenous immunoglobulin (IVIG responders (n=89 and nonresponders (n=31 with KD. Total U-LDH activity was higher in KD (35.4±4.8 IU/L, P<0.05 and UTI patients (66.0±8.0 IU/L, P<0.01 than in VI patients (17.0±6.2 IU/L. In the isozyme pattern analysis, KD patients had high levels of U-LDH1 and U-LDH2, while UTI patients had high levels of U-LDH3, U-LDH4, and U-LDH5. Furthermore, IVIG nonresponders of KD had significantly higher levels of total U-LDH activity (45.1±4.7 IU/L, P<0.05, especially U-LDH1 and U-LDH2 (P<0.05, than IVIG responders (32.0±2.8 IU/L. KD patients have increased levels of total U-LDH activity, especially U-LDH-1 and U-LDH2, indicating a unique pattern of U-LDH isozymes different from that in UTI patients.

Enzymatic Kinetic Properties of the Lactate Dehydrogenase Isoenzyme C4 of the Plateau Pika (Ochotona curzoniae

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Yang Wang

2016-01-01

Full Text Available Testis-specific lactate dehydrogenase (LDH-C4 is one of the lactate dehydrogenase (LDH isozymes that catalyze the terminal reaction of pyruvate to lactate in the glycolytic pathway. LDH-C4 in mammals was previously thought to be expressed only in spermatozoa and testis and not in other tissues. Plateau pika (Ochotona curzoniae belongs to the genus Ochotona of the Ochotonidea family. It is a hypoxia-tolerant species living in remote mountain areas at altitudes of 3000–5000 m above sea level on the Qinghai-Tibet Plateau. Surprisingly, Ldh-c is expressed not only in its testis and sperm, but also in somatic tissues of plateau pika. To shed light on the function of LDH-C4 in somatic cells, Ldh-a, Ldh-b, and Ldh-c of plateau pika were subcloned into bacterial expression vectors. The pure enzymes of Lactate Dehydrogenase A4 (LDH-A4, Lactate Dehydrogenase B4 (LDH-B4, and LDH-C4 were prepared by a series of expression and purification processes, and the three enzymes were identified by the method of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE and native polyacrylamide gel electrophoresis (PAGE. The enzymatic kinetics properties of these enzymes were studied by Lineweaver-Burk double-reciprocal plots. The results showed the Michaelis constant (Km of LDH-C4 for pyruvate and lactate was 0.052 and 4.934 mmol/L, respectively, with an approximate 90 times higher affinity of LDH-C4 for pyruvate than for lactate. At relatively high concentrations of lactate, the inhibition constant (Ki of the LDH isoenzymes varied: LDH-A4 (Ki = 26.900 mmol/L, LDH-B4 (Ki = 23.800 mmol/L, and LDH-C4 (Ki = 65.500 mmol/L. These data suggest that inhibition of lactate by LDH-A4 and LDH-B4 were stronger than LDH-C4. In light of the enzymatic kinetics properties, we suggest that the plateau pika can reduce reliance on oxygen supply and enhance its adaptation to the hypoxic environments due to increased anaerobic glycolysis by LDH-C4.

Divergent lactate dehydrogenase isoenzyme profile in cellular compartments of primate forebrain structures.

Science.gov (United States)

Duka, Tetyana; Collins, Zachary; Anderson, Sarah M; Raghanti, Mary Ann; Ely, John J; Hof, Patrick R; Wildman, Derek E; Goodman, Morris; Grossman, Lawrence I; Sherwood, Chet C

2017-07-01

The compartmentalization and association of lactate dehydrogenase (LDH) with specific cellular structures (e.g., synaptosomal, sarcoplasmic or mitochondrial) may play an important role in brain energy metabolism. Our previous research revealed that LDH in the synaptosomal fraction shifts toward the aerobic isoforms (LDH-B) among the large-brained haplorhine primates compared to strepsirrhines. Here, we further analyzed the subcellular localization of LDH in primate forebrain structures using quantitative Western blotting and ELISA. We show that, in cytosolic and mitochondrial subfractions, LDH-B expression level was relatively elevated and LDH-A declined in haplorhines compared to strepsirrhines. LDH-B expression in mitochondrial fractions of the neocortex was preferentially increased, showing a particularly significant rise in the ratio of LDH-B to LDH-A in chimpanzees and humans. We also found a significant correlation between the protein levels of LDH-B in mitochondrial fractions from haplorhine neocortex and the synaptosomal LDH-B that suggests LDH isoforms shift from a predominance of A-subunits toward B-subunits as part of a system that spatially buffers dynamic energy requirements of brain cells. Our results indicate that there is differential subcellular compartmentalization of LDH isoenzymes that evolved among different primate lineages to meet the energy requirements in neocortical and striatal cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Major Role of NAD-Dependent Lactate Dehydrogenases in the Production of l-Lactic Acid with High Optical Purity by the Thermophile Bacillus coagulans.

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Wang, Limin; Cai, Yumeng; Zhu, Lingfeng; Guo, Honglian; Yu, Bo

2014-12-01

Bacillus coagulans 2-6 is an excellent producer of optically pure l-lactic acid. However, little is known about the mechanism of synthesis of the highly optically pure l-lactic acid produced by this strain. Three enzymes responsible for lactic acid production-NAD-dependent l-lactate dehydrogenase (l-nLDH; encoded by ldhL), NAD-dependent d-lactate dehydrogenase (d-nLDH; encoded by ldhD), and glycolate oxidase (GOX)-were systematically investigated in order to study the relationship between these enzymes and the optical purity of lactic acid. Lactobacillus delbrueckii subsp. bulgaricus DSM 20081 (a d-lactic acid producer) and Lactobacillus plantarum subsp. plantarum DSM 20174 (a dl-lactic acid producer) were also examined in this study as comparative strains, in addition to B. coagulans. The specific activities of key enzymes for lactic acid production in the three strains were characterized in vivo and in vitro, and the levels of transcription of the ldhL, ldhD, and GOX genes during fermentation were also analyzed. The catalytic activities of l-nLDH and d-nLDH were different in l-, d-, and dl-lactic acid producers. Only l-nLDH activity was detected in B. coagulans 2-6 under native conditions, and the level of transcription of ldhL in B. coagulans 2-6 was much higher than that of ldhD or the GOX gene at all growth phases. However, for the two Lactobacillus strains used in this study, ldhD transcription levels were higher than those of ldhL. The high catalytic efficiency of l-nLDH toward pyruvate and the high transcription ratios of ldhL to ldhD and ldhL to the GOX gene provide the key explanations for the high optical purity of l-lactic acid produced by B. coagulans 2-6. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

OXIDATION OF CYCLOHEXANOL ON PHOSPHOTUNGSTIC ACID ANION INTERCALATED LAYERED DOUBLE HYDROXIDES WITH AQUEOUS H2O2 AS OXIDANT

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Xueli Bai

Full Text Available The layered double hydroxides (LDH of Mg2AlNi and Mg3Al pillared by Keggin-type phosphotungstic acid anion (POM, i.e. Mg2AlNi-POM LDH and Mg3Al-POM LDH were synthesized by an ion-exchange method. The synthesized POM intercalated LDH compounds were characterized using various techniques such as FTIR, XRD, TGA and BET. The observed results show that the obtained catalysts retain the layer structure of LDH. Compared with the binary Mg3Al-POM LDH, the ternary Mg2AlNi-POM LDH catalyst indicated a higher thermal and chemical stability. The catalytic activity of the resulting LDH-POM was also assessed in the green oxidation of cyclohexanol with aqueous H2O2 as an oxidant. The Mg2AlNi-POM LDH showed a much higher conversion and selectivity for cyclohexanone than the corresponding Mg3Al-POM LDH catalyst.

Oxidation of cyclohexanol on phosphotungstic acid anion intercalated layered double hydroxides with aqueous H{sub 2}O{sub 2} as oxidant

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Bai, Xueli; Xue, Dandan; Sun, Huiyan; Huang, Xin; Zhao, Yongxiang; Zhang, Yue, E-mail: zyue@sxu.edu.cn [School of Chemical Engineering, Shanxi University, Shanxi (China); Bai, Zhaoyang [Shanxi Agricultural University, Shanxi (China)

2018-01-15

The layered double hydroxides (LDH) of Mg{sub 2}AlNi and Mg{sub 3}Al pillared by Keggin-type phosphotungstic acid anion (POM), i.e. Mg{sub 2}AlNi-POM LDH and Mg{sub 3}Al-POM LDH were synthesized by an ion-exchange method. The synthesized POM intercalated LDH compounds were characterized using various techniques such as FTIR, XRD, TGA and BET. The observed results show that the obtained catalysts retain the layer structure of LDH. Compared with the binary Mg{sub 3}Al-POM LDH, the ternary Mg{sub 2}AlNi-POM LDH catalyst indicated a higher thermal and chemical stability. The catalytic activity of the resulting LDH-POM was also assessed in the green oxidation of cyclohexanol with aqueous H{sub 2}O{sub 2} as an oxidant. The Mg{sub 2}AlNi-POM LDH showed a much higher conversion and selectivity for cyclohexanone than the corresponding Mg{sub 3}Al-POM LDH catalyst. (author)

Transcription of the extended hyp-operon in Nostoc sp. strain PCC 7120

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Lindblad Peter

2008-04-01

Full Text Available Abstract Background The maturation of hydrogenases into active enzymes is a complex process and e.g. a correctly assembled active site requires the involvement of at least seven proteins, encoded by hypABCDEF and a hydrogenase specific protease, encoded either by hupW or hoxW. The N2-fixing cyanobacterium Nostoc sp. strain PCC 7120 may contain both an uptake and a bidirectional hydrogenase. The present study addresses the presence and expression of hyp-genes in Nostoc sp. strain PCC 7120. Results RT-PCRs demonstrated that the six hyp-genes together with one ORF may be transcribed as a single operon. Transcriptional start points (TSPs were identified 280 bp upstream from hypF and 445 bp upstream of hypC, respectively, demonstrating the existence of several transcripts. In addition, five upstream ORFs located in between hupSL, encoding the small and large subunits of the uptake hydrogenase, and the hyp-operon, and two downstream ORFs from the hyp-genes were shown to be part of the same transcript unit. A third TSP was identified 45 bp upstream of asr0689, the first of five ORFs in this operon. The ORFs are annotated as encoding unknown proteins, with the exception of alr0692 which is identified as a NifU-like protein. Orthologues of the four ORFs asr0689-alr0692, with a highly conserved genomic arrangement positioned between hupSL, and the hyp genes are found in several other N2-fixing cyanobacteria, but are absent in non N2-fixing cyanobacteria with only the bidirectional hydrogenase. Short conserved sequences were found in six intergenic regions of the extended hyp-operon, appearing between 11 and 79 times in the genome. Conclusion This study demonstrated that five ORFs upstream of the hyp-gene cluster are co-transcribed with the hyp-genes, and identified three TSPs in the extended hyp-gene cluster in Nostoc sp. strain PCC 7120. This may indicate a function related to the assembly of a functional uptake hydrogenase, hypothetically in the

Characterization of the hupSL promoter activity in Nostoc punctiforme ATCC 29133

Science.gov (United States)

2009-01-01

Background In cyanobacteria three enzymes are directly involved in the hydrogen metabolism; a nitrogenase that produces molecular hydrogen, H2, as a by-product of nitrogen fixation, an uptake hydrogenase that recaptures H2 and oxidize it, and a bidirectional hydrogenase that can both oxidize and produce H2.Nostoc punctiforme ATCC 29133 is a filamentous dinitrogen fixing cyanobacterium containing a nitrogenase and an uptake hydrogenase but no bidirectional hydrogenase. Generally, little is known about the transcriptional regulation of the cyanobacterial uptake hydrogenases. In this study gel shift assays showed that NtcA has a specific affinity to a region of the hupSL promoter containing a predicted NtcA binding site. The predicted NtcA binding site is centred at 258.5 bp upstream the transcription start point (tsp). To further investigate the hupSL promoter, truncated versions of the hupSL promoter were fused to either gfp or luxAB, encoding the reporter proteins Green Fluorescent Protein and Luciferase, respectively. Results Interestingly, all hupsSL promoter deletion constructs showed heterocyst specific expression. Unexpectedly the shortest promoter fragment, a fragment covering 57 bp upstream and 258 bp downstream the tsp, exhibited the highest promoter activity. Deletion of the NtcA binding site neither affected the expression to any larger extent nor the heterocyst specificity. Conclusion Obtained data suggest that the hupSL promoter in N. punctiforme is not strictly dependent on the upstream NtcA cis element and that the shortest promoter fragment (-57 to tsp) is enough for a high and heterocyst specific expression of hupSL. This is highly interesting because it indicates that the information that determines heterocyst specific gene expression might be confined to this short sequence or in the downstream untranslated leader sequence. PMID:19284581

Characterization of the hupSL promoter activity in Nostoc punctiforme ATCC 29133

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Lindberg Pia

2009-03-01

Full Text Available Abstract Background In cyanobacteria three enzymes are directly involved in the hydrogen metabolism; a nitrogenase that produces molecular hydrogen, H2, as a by-product of nitrogen fixation, an uptake hydrogenase that recaptures H2 and oxidize it, and a bidirectional hydrogenase that can both oxidize and produce H2.Nostoc punctiforme ATCC 29133 is a filamentous dinitrogen fixing cyanobacterium containing a nitrogenase and an uptake hydrogenase but no bidirectional hydrogenase. Generally, little is known about the transcriptional regulation of the cyanobacterial uptake hydrogenases. In this study gel shift assays showed that NtcA has a specific affinity to a region of the hupSL promoter containing a predicted NtcA binding site. The predicted NtcA binding site is centred at 258.5 bp upstream the transcription start point (tsp. To further investigate the hupSL promoter, truncated versions of the hupSL promoter were fused to either gfp or luxAB, encoding the reporter proteins Green Fluorescent Protein and Luciferase, respectively. Results Interestingly, all hupsSL promoter deletion constructs showed heterocyst specific expression. Unexpectedly the shortest promoter fragment, a fragment covering 57 bp upstream and 258 bp downstream the tsp, exhibited the highest promoter activity. Deletion of the NtcA binding site neither affected the expression to any larger extent nor the heterocyst specificity. Conclusion Obtained data suggest that the hupSL promoter in N. punctiforme is not strictly dependent on the upstream NtcA cis element and that the shortest promoter fragment (-57 to tsp is enough for a high and heterocyst specific expression of hupSL. This is highly interesting because it indicates that the information that determines heterocyst specific gene expression might be confined to this short sequence or in the downstream untranslated leader sequence.

Molecular hydrogen is involved in phytohormone signaling and stress responses in plants.

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Jiqing Zeng

Full Text Available Molecular hydrogen (H2 metabolism in bacteria and algae has been well studied from an industrial perspective because H2 is viewed as a potential future energy source. A number of clinical trials have recently reported that H2 is a therapeutic antioxidant and signaling molecule. Although H2 metabolism in higher plants was reported in some early studies, its biological effects remain unclear. In this report, the biological effects of H2 and its involvement in plant hormone signaling pathways and stress responses were determined. Antioxidant enzyme activity was found to be increased and the transcription of corresponding genes altered when the effects of H2 on the germination of mung bean seeds treated with phytohormones was investigated. In addition, upregulation of several phytohormone receptor genes and genes that encode a few key factors involved in plant signaling pathways was detected in rice seedlings treated with HW. The transcription of putative rice hydrogenase genes, hydrogenase activity, and endogenous H2 production were also determined. H2 production was found to be induced by abscisic acid, ethylene, and jasmonate acid, salt, and drought stress and was consistent with hydrogenase activity and the expression of putative hydrogenase genes in rice seedlings. Together, these results suggest that H2 may have an effect on rice stress tolerance by modulating the output of hormone signaling pathways.

Expression and prognostic value of lactate dehydrogenase-A and -D subunits in human uterine myoma and uterine sarcoma.

Science.gov (United States)

Song, Ke-Juan; Yu, Xiao-Ni; Lv, Teng; Chen, Yu-Long; Diao, Yu-Chao; Liu, Su-Li; Wang, Yan-Kui; Yao, Qin

2018-04-01

This study aimed to determine the expression of lactate dehydrogenase (LDH)-A and LDH-D in patients with uterine myoma, cellular leiomyoma (CLM), and uterine sarcoma and to evaluate their prognostic significance. Protein expression levels of LDH-A and LDH-D were determined in tissue samples from 86 patients (26 uterine myoma, 10 CLM, 50 uterine sarcoma) by immunohistochemistry and their associations with clinicopathologic parameters and outcomes were analyzed in patients with uterine sarcoma. The positivity rates for LDH-A and LDH-D were significantly higher in patients with uterine sarcoma compared with those with uterine myoma or CLM (P sarcoma were classified as having uterine leiomyosarcoma (LMS), malignant endometrial stromal sarcoma, and malignant mixed Mullerian tumor, with 5-year overall survival rates of 59%, 71%, and 29%, respectively (P sarcoma. Furthermore, the overexpressions of LDH-A and LDH-D in uterine sarcoma patients may contribute to further understanding of the mechanism of LDH in tumor metabolism in uterine sarcoma. Positive expression of LDH-A in patients with LMS may act as a potential prognostic biomarker in these patients.

Lactate-Dehydrogenase 5 is overexpressed in non-small cell lung cancer and correlates with the expression of the transketolase-like protein 1

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Stickeler Elmar

2010-04-01

Full Text Available Abstract Aims As one of the five Lactate dehydrogenase (LDH isoenzymes, LDH5 has the highest efficiency to catalyze pyruvate transformation to lactate. LDH5 overexpression in cancer cells induces an upregulated glycolytic metabolism and reduced dependence on the presence of oxygen. Here we analyzed LDH5 protein expression in a well characterized large cohort of primary lung cancers in correlation to clinico-pathological data and its possible impact on patient survival. Methods Primary lung cancers (n = 269 and non neoplastic lung tissue (n = 35 were tested for LDH5 expression by immunohistochemistry using a polyclonal LDH5 antibody (ab53010. The results of LDH5 expression were correlated to clinico-pathological data as well as to patient's survival. In addition, the results of the previously tested Transketolase like 1 protein (TKTL1 expression were correlated to LDH5 expression. Results 89.5% (n = 238 of NSCLC revealed LDH5 expression whereas LDH5 expression was not detected in non neoplastic lung tissues (n = 34 (p Conclusions LDH5 is overexpressed in NSCLC and could hence serve as an additional marker for malignancy. Furthermore, LDH5 correlates positively with the prognostic marker TKTL1. Our results confirm a close link between the two metabolic enzymes and indicate an alteration in the glucose metabolism in the process of malignant transformation.

Large-scale fabrication of linear low density polyethylene/layered double hydroxides composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties

Energy Technology Data Exchange (ETDEWEB)

Xie, Jiazhuo; Zhang, Kun; Zhao, Qinghua [College of Chemistry and Material Science, Shandong Agricultural University, 61 Daizong Street, Tai' an 271018 (China); Wang, Qingguo, E-mail: wqgyyy@126.com [College of Food Science and Engineering, Shandong Agricultural University, 61 Daizong Street, Tai' an 271018 (China); Xu, Jing, E-mail: jiaxu@sdau.edu.cn [College of Chemistry and Material Science, Shandong Agricultural University, 61 Daizong Street, Tai' an 271018 (China)

2016-11-15

Novel LDH intercalated with organic aliphatic long-chain anion was large-scale synthesized innovatively by high-energy ball milling in one pot. The linear low density polyethylene (LLDPE)/layered double hydroxides (LDH) composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties were fabricated by melt blending and blowing process. FT IR, XRD, SEM results show that LDH particles were dispersed uniformly in the LLDPE composite films. Particularly, LLDPE composite film with 1% LDH exhibited the optimal performance among all the composite films with a 60.36% enhancement in the water vapor barrier property and a 45.73 °C increase in the temperature of maximum mass loss rate compared with pure LLDPE film. Furthermore, the improved infrared absorbance (1180–914 cm{sup −1}) of LLDPE/LDH films revealed the significant enhancement of heat retention. Therefore, this study prompts the application of LLDPE/LDH films as agricultural films with superior heat retention. - Graphical abstract: The fabrication process of LLDPE/LDH composite films. - Highlights: • LDH with basal spacing of 4.07 nm was synthesized by high-energy ball milling. • LLDPE composite films with homogeneous LDH dispersion were fabricated. • The properties of LLDPE/LDH composite films were improved. • LLDPE/LDH composite films show superior heat retention property.

Changes in lactate dehydrogenase are associated with central gray matter lesions in newborns with hypoxic-ischemic encephalopathy.

Science.gov (United States)

Yum, Sook Kyung; Moon, Cheong-Jun; Youn, Young-Ah; Sung, In Kyung

2017-05-01

Biomarkers may predict neurological prognosis in infants with hypoxic-ischemic encephalopathy (HIE). We evaluated the relationship between serum lactate dehydrogenase (LDH) and brain magnetic resonance imaging (MRI), which predicts neurodevelopmental outcomes, in order to assess whether LDH levels are similarly predictive. Medical records were reviewed for infants with HIE and LDH levels were assessed on the first (LDH 1 ) and third (LDH 3 ) days following birth. Receiver operating characteristic curves were obtained in relation to central gray matter hypoxic-ischemic lesions. Of 92 patients, 52 (56.5%) had hypoxic-ischemic lesions on brain MRI, and 21 of these infants (40.4%) had central gray matter lesions. LDH 1 and LDH 3 did not differ; however, the percentage change (ΔLDH%) was significantly higher in infants with central gray matter lesions (36.9% versus 6.6%, p = 0.006). With cutoffs of 187 (IU/L, ΔLDH) and 19.4 (%, ΔLDH%), the sensitivity, specificity, positive predictive value and negative predictive value were 71.4, 69.0, 40.5 and 89.1%, respectively. The relative risk was 5.57 (p = 0.001). Changes in serum LDH may be a useful biomarker for predicting future neurodevelopmental prognosis in infants with HIE.

Large-scale fabrication of linear low density polyethylene/layered double hydroxides composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties

International Nuclear Information System (INIS)

Xie, Jiazhuo; Zhang, Kun; Zhao, Qinghua; Wang, Qingguo; Xu, Jing

2016-01-01

Novel LDH intercalated with organic aliphatic long-chain anion was large-scale synthesized innovatively by high-energy ball milling in one pot. The linear low density polyethylene (LLDPE)/layered double hydroxides (LDH) composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties were fabricated by melt blending and blowing process. FT IR, XRD, SEM results show that LDH particles were dispersed uniformly in the LLDPE composite films. Particularly, LLDPE composite film with 1% LDH exhibited the optimal performance among all the composite films with a 60.36% enhancement in the water vapor barrier property and a 45.73 °C increase in the temperature of maximum mass loss rate compared with pure LLDPE film. Furthermore, the improved infrared absorbance (1180–914 cm −1 ) of LLDPE/LDH films revealed the significant enhancement of heat retention. Therefore, this study prompts the application of LLDPE/LDH films as agricultural films with superior heat retention. - Graphical abstract: The fabrication process of LLDPE/LDH composite films. - Highlights: • LDH with basal spacing of 4.07 nm was synthesized by high-energy ball milling. • LLDPE composite films with homogeneous LDH dispersion were fabricated. • The properties of LLDPE/LDH composite films were improved. • LLDPE/LDH composite films show superior heat retention property.

Ontogenetic changes and developmental adjustments in lactate dehydrogenase isozymes of an obligate air-breathing fish Channa punctatus during deprivation of air access.

Science.gov (United States)

Ahmad, Riaz; Hasnain, Absar-Ul

2005-02-01

In air-breathing snakehead Channa punctatus, Ldh-B is expressed at all ontogenetic and developmental stages, while Ldh-A is expressed temporally in pre-hatchlings 12-13 days ahead of bimodal respiration marked by air-breathing. Remarkable differences are observed in the LDH isozyme expression among various ontogenetic and developmental stages upon denying air access. When denied air access, water-breathing larvae show two distinct characteristics: (i) they survive longer than transitory air-breathers due to independence from air-breathing and (ii) there is more transient induction of Ldh-B than Ldh-A. Transition to bimodal breathing, which occurred post-hatching in 15-day old larvae, is coincidental with inducibility of Ldh-A and concomitant down-regulation of Ldh-B. Heart tissue from air-breathing adults denied air access shows a preferential expression of LDH-A subunit and slight down-regulation of LDH-B. Heterotetramers of A and B subunits participate in adjusting LDH levels among those stages which either precede air-breathing switchover, or are subsequent to this transition. The contribution of heterotetramers depends on the stage-specific levels of LDH homotetramers A(4) or B(4). Scaling of muscle mass during growth, tolerance to extended deprivation of air access and induction of Ldh-A are correlated. Response to restoring air contact indicated that advanced air-breathing stages of C. punctatus possess an inherent capacity to sense surface air. In kinetic properties, LDH isozymes of C. punctatus are teleost-like but species specificity is displayed in oxidative potential by cardiac muscle and in L-lactate reduction by skeletal muscle.

Photoproduction of hydrogen - A potential system of solar energy bioconversion

Energy Technology Data Exchange (ETDEWEB)

Das, V S.R.

1979-10-01

The photoproduction of hydrogen from water utilizing the photosynthetic capacity of green plants is discussed as a possible means of solar energy conversion. Advantages of the biological production of H/sub 2/ over various physical and chemical processes are pointed out, and the system used for the production of hydrogen by biological agents, which comprises the photosynthetic electron transport chain, ferredoxin and hydrogenase, is examined in detail. The various types of biological hydrogen production systems in bacteria, algae, symbiotic systems and isolated chloroplast-ferredoxin-hydrogenase systems are reviewed. The limitations and the scope for further improvement of the promising symbiotic Azolli-Anabena azollae and chloroplast-ferredoxin-hydrogenase are discussed, and it is concluded that future research should concern itself with the identification of the environmental conditions that would maximize solar energy conversion efficiency, the elimination of the oxygen inhibition of biological hydrogen production, and the definition of the metabolic state for the maximal production of hydrogen.

Electrospun fibers of layered double hydroxide/biopolymer nanocomposites as effective drug delivery systems

Energy Technology Data Exchange (ETDEWEB)

Miao, Yue-E.; Zhu Hong; Chen Dan; Wang Ruiyu [State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Tjiu, Weng Weei [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Liu Tianxi, E-mail: txliu@fudan.edu.cn [State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China)

2012-06-15

Ibuprofen intercalated layered double hydroxide (LDH-IBU)/polycaprolactone (PCL) and LDH-IBU/polylactide (PLA) nanocomposite fibers are electrospun based on a combination of LDH-IBU with two kinds of biopolymers (i.e. PCL and PLA), to act as effective drug delivery systems. Ibuprofen (IBU) is chosen as a model drug, which is intercalated in MgAl-LDH by coprecipitation. Poly(oxyethylene-b-oxypropylene-b-oxyethylene) (Pluronic) is also added into PLA-based fibers as hydrophilicity enhancer and release modulator. LDH-IBU nanoparticles are uniformly dispersed throughout the nanocomposite fibers, as evidenced by transmission electron microscopy (TEM) observations. In vitro drug release studies show that initial IBU liberation from LDH-IBU/PCL composite fibers is remarkably slower than that from IBU/PCL fibers due to the sustained release property of LDH-IBU and heterogeneous nucleation effect of LDH-IBU on PCL chain segments. Surprisingly, the initial IBU release from LDH-IBU/PLA and LDH-IBU/PLA/Pluronic composite fibers is faster than that from the corresponding IBU/PLA and IBU/PLA/Pluronic fibers. This effect can be attributed to the strong interaction between alkyl groups in IBU molecules and methyl substituent groups of PLA as well as the hydrophilicity of LDH-IBU, which lead to an easier diffusion of water with a faster release of IBU from LDH-IBU/PLA and LDH-IBU/PLA/Pluronic composite fibers. - Graphical abstract: Ibuprofen intercalated layered double hydroxide (LDH-IBU)/polycaprolactone (PCL) and LDH-IBU/polylactide (PLA) nanocomposite fibers are electrospun based on the combination of LDHs with two kinds of biopolymers (i.e. PCL and PLA). LDH-IBU nanoparticles are uniformly dispersed throughout all the electrospun nanocomposite fibers even at a high loading level of 5 wt%. By combining the tunable drug release property of LDHs and electrospinning technique, the new drug delivery system is anticipated for effective loading and sustained release of drugs

Electrospun fibers of layered double hydroxide/biopolymer nanocomposites as effective drug delivery systems

International Nuclear Information System (INIS)

Miao, Yue-E.; Zhu Hong; Chen Dan; Wang Ruiyu; Tjiu, Weng Weei; Liu Tianxi

2012-01-01

Ibuprofen intercalated layered double hydroxide (LDH-IBU)/polycaprolactone (PCL) and LDH-IBU/polylactide (PLA) nanocomposite fibers are electrospun based on a combination of LDH-IBU with two kinds of biopolymers (i.e. PCL and PLA), to act as effective drug delivery systems. Ibuprofen (IBU) is chosen as a model drug, which is intercalated in MgAl-LDH by coprecipitation. Poly(oxyethylene-b-oxypropylene-b-oxyethylene) (Pluronic) is also added into PLA-based fibers as hydrophilicity enhancer and release modulator. LDH-IBU nanoparticles are uniformly dispersed throughout the nanocomposite fibers, as evidenced by transmission electron microscopy (TEM) observations. In vitro drug release studies show that initial IBU liberation from LDH-IBU/PCL composite fibers is remarkably slower than that from IBU/PCL fibers due to the sustained release property of LDH-IBU and heterogeneous nucleation effect of LDH-IBU on PCL chain segments. Surprisingly, the initial IBU release from LDH-IBU/PLA and LDH-IBU/PLA/Pluronic composite fibers is faster than that from the corresponding IBU/PLA and IBU/PLA/Pluronic fibers. This effect can be attributed to the strong interaction between alkyl groups in IBU molecules and methyl substituent groups of PLA as well as the hydrophilicity of LDH-IBU, which lead to an easier diffusion of water with a faster release of IBU from LDH-IBU/PLA and LDH-IBU/PLA/Pluronic composite fibers. - Graphical abstract: Ibuprofen intercalated layered double hydroxide (LDH-IBU)/polycaprolactone (PCL) and LDH-IBU/polylactide (PLA) nanocomposite fibers are electrospun based on the combination of LDHs with two kinds of biopolymers (i.e. PCL and PLA). LDH-IBU nanoparticles are uniformly dispersed throughout all the electrospun nanocomposite fibers even at a high loading level of 5 wt%. By combining the tunable drug release property of LDHs and electrospinning technique, the new drug delivery system is anticipated for effective loading and sustained release of drugs

Purification and Properties of White Muscle Lactate Dehydrogenase from the Anoxia-Tolerant Turtle, the Red-Eared Slider, Trachemys scripta elegans

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Neal J. Dawson

2013-01-01

Full Text Available Lactate dehydrogenase (LDH; E.C. 1.1.1.27 is a crucial enzyme involved in energy metabolism in muscle, facilitating the production of ATP via glycolysis during oxygen deprivation by recycling NAD+. The present study investigated purified LDH from the muscle of 20 h anoxic and normoxic T. s. elegans, and LDH from anoxic muscle showed a significantly lower (47% Km for L-lactate and a higher Vmax value than the normoxic form. Several lines of evidence indicated that LDH was converted to a low phosphate form under anoxia: (a stimulation of endogenously present protein phosphatases decreased the Km of L-lactate of control LDH to anoxic levels, whereas (b stimulation of kinases increased the Km of L-lactate of anoxic LDH to normoxic levels, and (c dot blot analysis shows significantly less serine (78% and threonine (58% phosphorylation in anoxic muscle LDH as compared to normoxic LDH. The physiological consequence of anoxia-induced LDH dephosphorylation appears to be an increase in LDH activity to promote the reduction of pyruvate in muscle tissue, converting the glycolytic end product to lactate to maintain a prolonged glycolytic flux under energy-stressed anoxic conditions.

Purification and Properties of White Muscle Lactate Dehydrogenase from the Anoxia-Tolerant Turtle, the Red-Eared Slider, Trachemys scripta elegans.

Science.gov (United States)

Dawson, Neal J; Bell, Ryan A V; Storey, Kenneth B

2013-01-01

Lactate dehydrogenase (LDH; E.C. 1.1.1.27) is a crucial enzyme involved in energy metabolism in muscle, facilitating the production of ATP via glycolysis during oxygen deprivation by recycling NAD(+). The present study investigated purified LDH from the muscle of 20 h anoxic and normoxic T. s. elegans, and LDH from anoxic muscle showed a significantly lower (47%) K m for L-lactate and a higher V max value than the normoxic form. Several lines of evidence indicated that LDH was converted to a low phosphate form under anoxia: (a) stimulation of endogenously present protein phosphatases decreased the K m of L-lactate of control LDH to anoxic levels, whereas (b) stimulation of kinases increased the K m of L-lactate of anoxic LDH to normoxic levels, and (c) dot blot analysis shows significantly less serine (78%) and threonine (58%) phosphorylation in anoxic muscle LDH as compared to normoxic LDH. The physiological consequence of anoxia-induced LDH dephosphorylation appears to be an increase in LDH activity to promote the reduction of pyruvate in muscle tissue, converting the glycolytic end product to lactate to maintain a prolonged glycolytic flux under energy-stressed anoxic conditions.

Stabilization of antioxidant gallate in layered double hydroxide by exfoliation and reassembling reaction

Science.gov (United States)

Ansy, Kanakappan Mickel; Lee, Ji-Hee; Piao, Huiyan; Choi, Goeun; Choy, Jin-Ho

2018-06-01

As for the stabilization of chemically sensitive bioactive molecule in this study, gallic acid (GA) with antioxidant property was intercalated into interlayer space of layered double hydroxide (LDH), which was realized by exfoliation and reassembling reaction. At first, the pristine nitrate-type Zn2Al-LDH in solid state was synthesized via co-precipitation followed by the hydrothermal treatment at 80 °C for 6 h, and then exfoliated in formamide to form a colloidal solution of exfoliated LDH nanosheets, and finally reassembled in the presence of GA to prepare GA intercalated LDH (GA-LDH) desired, where the pH was adjusted to 8.0 in order to deprotonate GA to form gallate anion. According to the XRD analysis, GA-LDH showed well-developed (00l) diffraction peaks with a basal spacing of 1.15 nm, which was estimated to be larger than that of the pristine LDH (0.88 nm), indicating that gallate molecules were incorporated into LDH layers with perpendicular orientation. From the FT-IR spectra it was found that gallic acid was completely deprotonated into gallate, and stabilized in between LDH lattices via electrostatic interaction. The content of GA in GA-LDH was determined to be around 23 wt% by UV-vis spectroscopic study, which was also confirmed by HPLC analysis. According to the in-vitro release of GA out of GA-LDH in PBS solution (pH 7.4) at 4 °C, GA was sustainably released from GA-LDH nanohybrid up to 86% within 72 h. The antioxidant property of GA-LDH was almost the same with that of intact GA which was examined by DPPH. The photostability of GA-LDH under UV light irradiation was immensely enhanced compared to intact GA. It is, therefore, concluded that the present GA-LDH nanohybrid can be considered as an excellent antioxidant material with high chemical- and photo-stabilities, and controlled release property.

Occurrence and characterisation of the hydrogen-evolving enzyme in Frankia sp.

Energy Technology Data Exchange (ETDEWEB)

Mohapatra, A.; Leul, M.; Sellstedt, A. [Umeaa Plant Science Centre, Department of Plant Physiology, Umeaa University, S-901 87 Umeaa (Sweden); Sandstroem, G. [Karolinska Institutet, Department of Laboratory Medicine, Division of Clinical Bacteriology, Karelinska University Hospital, Huddinge, S-141 86 Stockholm (Sweden)

2006-09-15

An increase in hydrogen evolution from the hydrogen-evolving enzyme in the actinomycete Frankia was recorded in the presence of nickel. Immunogold localisation analysis of the intracellular distribution of hydrogenase proteins indicated that they were evenly distributed in the membranes and cytosol of both hyphae and vesicles. In addition, molecular characterisation of the hydrogen-evolving enzyme at the proteomic level, using two-dimensional gel electrophoresis combined with mass spectrometry, confirmed that the Frankia hydrogen-evolving enzyme is similar to the cyanobacterial bidirectional hydrogenase of Anabena siamensis. (author)

Pretreatment serum lactate dehydrogenase as a prognostic indicator for oral cavity squamous cell carcinoma.

Science.gov (United States)

Takenaka, Yukinori; Oya, Ryohei; Aoki, Kengo; Hamaguchi, Hiroko; Takemura, Kazuya; Nozawa, Masayuki; Kitamura, Takahiro; Yamamoto, Yoshifumi; Uno, Atsuhiko

2018-04-01

To examine whether lactate dehydrogenase (LDH) can predict the prognosis of oral cavity squamous cell carcinoma (OSCC) and to determine the optimal cut-off values for LDH. This retrospective study included 184 patients with OSCC, treated with surgery between 2006 and 2014. The association between LDH and T, N classification was investigated using the Mann-Whitney test. Cut-off values for LDH were determined with a recursive partitioning analysis (RPA). Survival rates were estimated using the Kaplan-Meier method. A Cox hazard model was used to assess the prognostic capability of LDH. There was no association between LDH and T or N classification (p = .657, .619, respectively). RPA determined the cut-off values for LDH as 160 and 220 IU/L. The five year survival for low-, moderate-, and high-LDH groups were 87.7, 73.7, and 50.9%, respectively (p < .001). The hazard ratios (HRs) for death in moderate- and high-LDH groups were 2.92 (95%CI =1.02-12.30, p = .001) and 7.36 (95%CI =2.54-31.20, p < .001), respectively. The model including LDH-based stratification (Akaike's information criterion (AIC) = 516) was better than the model including clinical stage (AIC =528). Pretreatment serum LDH is an independent prognostic factor for overall survival in patients with OSCC.

Strategy for synthesizing quantum dot-layered double hydroxide nanocomposites and their enhanced photoluminescence and photostability.

Science.gov (United States)

Cho, Seungho; Jung, Sungwook; Jeong, Sanghwa; Bang, Jiwon; Park, Joonhyuck; Park, Youngrong; Kim, Sungjee

2013-01-08

Layered double hydroxide-quantum dot (LDH-QD) composites are synthesized via a room temperature LDH formation reaction in the presence of QDs. InP/ZnS (core/shell) QD, a heavy metal free QD, is used as a model constituent. Interactions between QDs (with negative zeta potentials), decorated with dihydrolipoic acids, and inherently positively charged metal hydroxide layers of LDH during the LDH formations are induced to form the LDH-QD composites. The formation of the LDH-QD composites affords significantly enhanced photoluminescence quantum yields and thermal- and photostabilities compared to their QD counterparts. In addition, the fluorescence from the solid LDH-QD composite preserved the initial optical properties of the QD colloid solution without noticeable deteriorations such as red-shift or deep trap emission. Based on their advantageous optical properties, we also demonstrate the pseudo white light emitting diode, down-converted by the LDH-QD composites.

The interaction between aggrecan gene VNTR polymorphism and obesity in predicting incident symptomatic lumbar disc herniation.

Science.gov (United States)

Cong, Lin; Zhu, Yue; Pang, Hao; Guanjun, T U

2014-01-01

An association between aggrecan gene variable number of tandem repeats polymorphism (VNTR) and symptomatic lumbar disc herniation (LDH) has been reported in Chinese Han of Northern China, and obesity had previously been suspected of causing severe LDH. However, the interaction between aggrecan VNTR and obesity in symptomatic LDH has not been well studied. To examine the interaction between aggrecan VNTR and obesity in the susceptibility of symptomatic LDH, 259 participants participated in this study and donated a blood sample. The disease group comprised 61 patients already diagnosed with symptomatic LDH. The control group consisted of 198 healthy blood donors without symptoms of LDH who were not diagnosed with LDH. The aggrecan gene VNTR region was analyzed using polymerase chain reaction. The data indicated that between the two groups, participants carrying one or two alleles ≤25 repeats who were non-obese people showed a 1.057-fold increase in risk for symptomatic LDH (p = 0.895, changing the number of repeat alleles to 25 repeats who were obese people showed an 1.061-fold higher risk (p = 0.885, adding obesity to the mix alone did not demonstrably increase the risk of LDH), while participants carrying one or two alleles ≤25 repeats who were obese people showed a 4.667-fold increase in risk for symptomatic LDH (p = 0.0003, adding obesity plus changing the repeat allele number significantly increased the risk of LDH by 4.667). Overall, the findings suggest an underlying interaction between aggrecan VNTR and obesity in symptomatic LDH.

Genomic Characterization of Methanomicrobiales Reveals Three Classes of Methanogens

Energy Technology Data Exchange (ETDEWEB)

Anderson, Iain; Ulrich, Luke E.; Lupa, Boguslaw; Susanti, Dwi; Porat, Iris; Hooper, Sean D.; Lykidis, Athanasios; Sieprawska-Lupa, Magdalena; Dharmarajan, Lakshmi; Goltsman, Eugene; Lapidus, Alla; Saunders, Elizabeth; Han, Cliff; Land, Miriam; Lucas, Susan; Mukhopadhyay, Biswarup; Whitman, William B.; Woese, Carl; Bristow, James; Kyrpides, Nikos

2009-05-01

Methanomicrobiales is the least studied order of methanogens. While these organisms appear to be more closely related to the Methanosarcinales in ribosomal-based phylogenetic analyses, they are metabolically more similar to Class I methanogens. In order to improve our understanding of this lineage, we have completely sequenced the genomes of two members of this order, Methanocorpusculum labreanum Z and Methanoculleus marisnigri JR1, and compared them with the genome of a third, Methanospirillum hungatei JF-1. Similar to Class I methanogens, Methanomicrobiales use a partial reductive citric acid cycle for 2-oxoglutarate biosynthesis, and they have the Eha energy-converting hydrogenase. In common with Methanosarcinales, Methanomicrobiales possess the Ech hydrogenase and at least some of them may couple formylmethanofuran formation and heterodisulfide reduction to transmembrane ion gradients. Uniquely, M. labreanum and M. hungatei contain hydrogenases similar to the Pyrococcus furiosus Mbh hydrogenase, and all three Methanomicrobiales have anti-sigma factor and anti-anti-sigma factor regulatory proteins not found in other methanogens. Phylogenetic analysis based on seven core proteins of methanogenesis and cofactor biosynthesis places the Methanomicrobiales equidistant from Class I methanogens and Methanosarcinales. Our results indicate that Methanomicrobiales, rather than being similar to Class I methanogens or Methanomicrobiales, share some features of both and have some unique properties. We find that there are three distinct classes of methanogens: the Class I methanogens, the Methanomicrobiales (Class II), and the Methanosarcinales (Class III).

Isothermal crystallization and melting behavior of polypropylene/layered double hydroxide nanocomposites

International Nuclear Information System (INIS)

Lonkar, Sunil P.; Singh, R.P.

2009-01-01

The effect of layered double hydroxide (LDH) nanolayers on the crystallization behavior of polypropylene (PP) was studied based on the preparation of nanocomposites by a melt intercalation method. The isothermal crystallization kinetics and subsequent melting behavior of PP/LDH hybrids were studied with differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide-angle X-ray diffraction (WAXD). Studies revealed that the LDH promoted heterogeneous nucleation, accelerating the crystallization of PP. The Avrami equation successfully describes the isothermal crystallization kinetics of PP/LDH hybrids and signifies heterogeneous nucleation in crystal growth of PP. The varying values of Avrami exponent (n) and half crystallization time (t 1/2 ) of PP and PP/LDH hybrids describes overall crystallization behavior. The crystallite size (D hkl ) and distribution of different crystallites in PP varied in presence of LDH. A significant increase in melting temperature is observed for PP/LDH hybrids. The POM showed that smaller and less perfect crystals were formed in nanocomposites because of molecular interaction between PP chains and LDH. The value of fold surface free energy (σ e ) of PP chains decreased with increasing LDH content. Finally, the overall results signify that LDH at nanometer level acted as nucleating agent and accelerate the overall crystallization process of PP.

Molecular characterization and expression studies during melon fruit development and ripening of L-galactono-1,4-lactone dehydrogenase

DEFF Research Database (Denmark)

Pateraki, Irene; Sanmartin, Maite; Kalamaki, Mary S.

2004-01-01

of a GalLDH full-length cDNA from melon (Cucumis melo L.) are described. Melon genomic DNA Southern analysis indicated that CmGalLDH was encoded by a single gene. CmGalLDH mRNA accumulation was detected in all tissues studied, but differentially expressed during fruit development and seed germination....... It is hypothesized that induction of CmGalLDH gene expression in ripening melon fruit contributes to parallel increases in the AA content and so playing a role in the oxidative ripening process. Higher CmGalLDH message abundance in light-grown seedlings compared with those raised in the dark suggests that Cm......GalLDH expression is regulated by light. Finally, various stresses and growth regulators resulted in no significant change in steady state levels of CmGalLDH mRNA in 20-d-old melon seedlings. To the authors' knowledge, this is the first report of GalLDH transcript induction in seed germination and differential gene...

A comparison of corrosion inhibition of magnesium aluminum and zinc aluminum vanadate intercalated layered double hydroxides on magnesium alloys

Science.gov (United States)

Guo, Lian; Zhang, Fen; Lu, Jun-Cai; Zeng, Rong-Chang; Li, Shuo-Qi; Song, Liang; Zeng, Jian-Min

2018-04-01

The magnesium aluminum and zinc aluminum layered double hydroxides intercalated with NO3 -(MgAl-NO3-LDH and ZnAl-NO3-LDH) were prepared by the coprecipitation method, and the magnesium aluminum and the zinc aluminum layered double hydroxides intercalated with VO x -(MgAl-VO x -LDH and ZnAl-VO x -LDH) were prepared by the anion-exchange method. Morphologies, microstructures and chemical compositions of LDHs were investigated by SEM, EDS, XRD, FTIR, Raman and TG analyses. The immersion tests were carried to determine the corrosion inhibition properties of MgAl-VO x -LDH and ZnAl-VO x -LDH on AZ31 Mg alloys. The results showed that ZnAl-VO x -LDH possesses the best anion-exchange and inhibition abilities. The influence of treatment parameters on microstructures of LDHs were discussed. Additionally, an inhibition mechanism for ZnAl-VO x -LDH on the AZ31 magnesium alloy was proposed and discussed.

Removal of bacteria and viruses from waters using layered double hydroxide nanocomposites

Directory of Open Access Journals (Sweden)

Song Jin et al

2007-01-01

Full Text Available We have identified synthetic layered double hydroxides (LDH nanocomposites as an effective group of material for removing bacteria and viruses from water. In this study, LDH nanocomposites were synthesized and tested for removing biological contaminants. LDH was used to remove MS2 and X174 (indicator viruses, and Escherichia coli (an indicator bacterium from synthetic groundwater and to remove mixed communities of heterotrophic bacteria from raw river water. Our results indicate that LDH composed of magnesium–aluminium or zinc–aluminium has a viral and bacterial adsorption efficiency ≥99% at viral concentrations between 5.9×106 and 9.1×106 plaque forming units (pfu/L and bacterial concentrations between 1.6×1010 and 2.6×1010 colony forming units (cfu/L when exposed to LDH in a slurry suspension system. Adsorption densities of viruses and bacteria to LDH in suspension ranged from 1.4×1010 to 2.1×1010 pfu/kg LDH and 3.2×1013–5.2×1013 cfu/kg LDH, respectively. We also tested the efficiency of LDH in removing heterotrophic bacteria from raw river water. While removal efficiencies were still high (87–99%, the adsorption capacities of the two kinds of LDH were 4–5 orders of magnitude lower than when exposed to synthetic groundwater, depending on if the LDH was in suspension or a packed column, respectively.

Thermal Stability, Combustion Behavior, and Mechanical Property in a Flame-Retardant Polypropylene System

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Lili Wang

2017-01-01

Full Text Available In order to comprehensively improve the strength, toughness, flame retardancy, smoke suppression, and thermal stability of polypropylene (PP, layered double hydroxide (LDH Ni0.2Mg2.8Al–LDH was synthesized by a coprecipitation method coupled with the microwave-hydrothermal treatment. The X-ray diffraction (XRD, morphology, mechanical, thermal, and fire properties for PP composites containing 1 wt %–20 wt % Ni0.2Mg2.8Al–LDH were investigated. The cone calorimeter tests confirm that the peak heat release rate (pk–HRR of PP–20%LDH was decreased to 500 kW/m2 from the 1057 kW/m2 of PP. The pk–HRR, average mass loss rate (AMLR and effective heat of combustion (EHC analysis indicates that the condensed phase fire retardant mechanism of Ni0.2Mg2.8Al–LDH in the composites. The production rate and mean release yield of CO for composites gradually decrease as Ni0.2Mg2.8Al–LDH increases in the PP matrix. Thermal analysis indicates that the decomposition temperature for PP–5%LDH and PP–10%LDH is 34 °C higher than that of the pure PP. The mechanical tests reveal that the tensile strength of PP–1%LDH is 7.9 MPa higher than that of the pure PP. Furthermore, the elongation at break of PP–10%LDH is 361% higher than PP. In this work, the synthetic LDH Ni0.2Mg2.8Al–LDH can be used as a flame retardant, smoke suppressant, thermal stabilizer, reinforcing, and toughening agent of PP products.

Layered double hydroxide supported gold nanoclusters by glutathione-capped Au nanoclusters precursor method for highly efficient aerobic oxidation of alcohols

Science.gov (United States)

Li, Lun; Dou, Liguang; Zhang, Hui

2014-03-01

M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity or selectivity. The AuNCs/M(= Ni, Co)3Al-LDH catalysts present even higher alcohol oxidation activity than AuNCs/Mg3Al-LDH. Particularly, AuNCs/Ni3Al-LDH-0.22 exhibits the highest activity (46 500 h-1) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions attributed to its strongest Au-support synergy. The excellent activity and stability of AuNCs/M3Al-LDH catalysts render these materials promising candidates for green base-free selective oxidation of alcohols by molecular oxygen.M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity

Lactate dehydrogenase inhibition: exploring possible applications beyond cancer treatment.

Science.gov (United States)

Di Stefano, Giuseppina; Manerba, Marcella; Di Ianni, Lorenza; Fiume, Luigi

2016-04-01

Lactate dehydrogenase (LDH) inhibition is considered a worthwhile attempt in the development of innovative anticancer strategies. Unfortunately, in spite of the involvement of several research institutions and pharma-companies, the discovery of LDH inhibitors with drug-like properties seems a hardly resolvable challenge. While awaiting new advancements, in the present review we will examine other pathologic conditions characterized by increased glycolysis and LDH activity, which could potentially benefit from LDH inhibition. The rationale for targeting LDH activity in these contexts is the same justifying the LDH-based approach in anticancer therapy: because of the enzyme position at the end of glycolytic pathway, LDH inhibitors are not expected to hinder glucose metabolism of normal cells. Moreover, we will summarize the latest contributions in the discovery of enzyme inhibitors and try to glance over the reasons underlying the complexity of this research.

Global sequence diversity of the lactate dehydrogenase gene in Plasmodium falciparum.

Science.gov (United States)

Simpalipan, Phumin; Pattaradilokrat, Sittiporn; Harnyuttanakorn, Pongchai

2018-01-09

Antigen-detecting rapid diagnostic tests (RDTs) have been recommended by the World Health Organization for use in remote areas to improve malaria case management. Lactate dehydrogenase (LDH) of Plasmodium falciparum is one of the main parasite antigens employed by various commercial RDTs. It has been hypothesized that the poor detection of LDH-based RDTs is attributed in part to the sequence diversity of the gene. To test this, the present study aimed to investigate the genetic diversity of the P. falciparum ldh gene in Thailand and to construct the map of LDH sequence diversity in P. falciparum populations worldwide. The ldh gene was sequenced for 50 P. falciparum isolates in Thailand and compared with hundreds of sequences from P. falciparum populations worldwide. Several indices of molecular variation were calculated, including the proportion of polymorphic sites, the average nucleotide diversity index (π), and the haplotype diversity index (H). Tests of positive selection and neutrality tests were performed to determine signatures of natural selection on the gene. Mean genetic distance within and between species of Plasmodium ldh was analysed to infer evolutionary relationships. Nucleotide sequences of P. falciparum ldh could be classified into 9 alleles, encoding 5 isoforms of LDH. L1a was the most common allelic type and was distributed in P. falciparum populations worldwide. Plasmodium falciparum ldh sequences were highly conserved, with haplotype and nucleotide diversity values of 0.203 and 0.0004, respectively. The extremely low genetic diversity was maintained by purifying selection, likely due to functional constraints. Phylogenetic analysis inferred the close genetic relationship of P. falciparum to malaria parasites of great apes, rather than to other human malaria parasites. This study revealed the global genetic variation of the ldh gene in P. falciparum, providing knowledge for improving detection of LDH-based RDTs and supporting the candidacy of

Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

International Nuclear Information System (INIS)

Li, Shuo; Bhushan, Bharat

2016-01-01

Highlights: • Mg/Al-, Zn/Al- and Zn/Mg/Al-layered double hydroxide were synthesized. • Mg/Al-LDH had superior tribological performance compared to other LDHs. • The best thermal stability of Mg/Al-LDH was responsible for its friction property. - Abstract: Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

Energy Technology Data Exchange (ETDEWEB)

Li, Shuo [School of Materials Science and Technology, China University of Geosciences (Beijing), 29 Xueyuan Road, Haidian Distract, Beijing 100083 (China); Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue Columbus, OH 43210-1142 (United States); Bhushan, Bharat, E-mail: bhushan.2@osu.edu [Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue Columbus, OH 43210-1142 (United States)

2016-08-15

Highlights: • Mg/Al-, Zn/Al- and Zn/Mg/Al-layered double hydroxide were synthesized. • Mg/Al-LDH had superior tribological performance compared to other LDHs. • The best thermal stability of Mg/Al-LDH was responsible for its friction property. - Abstract: Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

Multifunctional organic–inorganic hybrid nanoparticles and nanosheets based on chitosan derivative and layered double hydroxide: cellular uptake mechanism and application for topical ocular drug delivery

Science.gov (United States)

Chi, Huibo; Gu, Yan; Xu, Tingting; Cao, Feng

2017-01-01

To study the cellular uptake mechanism of multifunctional organic–inorganic hybrid nanoparticles and nanosheets, new chitosan–glutathione–valine–valine-layered double hydroxide (CG-VV-LDH) nanosheets with active targeting to peptide transporter-1 (PepT-1) were prepared, characterized and further compared with CG-VV-LDH nanoparticles. Both organic–inorganic hybrid nanoparticles and nanosheets showed a sustained release in vitro and prolonged precorneal retention time in vivo, but CG-VV-LDH nanoparticles showed superior permeability in the isolated cornea of rabbits than CG-VV-LDH nanosheets. Furthermore, results of cellular uptake on human corneal epithelial primary cells (HCEpiC) and retinal pigment epithelial (ARPE-19) cells indicated that both clathrin-mediated endocytosis and active transport of PepT-1 are involved in the internalization of CG-VV-LDH nanoparticles and CG-VV-LDH nanosheets. In summary, the CG-VV-LDH nanoparticle may be a promising carrier as a topical ocular drug delivery system for the treatment of ocular diseases of mid-posterior segments, while the CG-VV-LDH nanosheet may be suitable for the treatment of ocular surface diseases. PMID:28280329

Lichen symbiosis: nature's high yielding machines for induced hydrogen production.

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Aikaterini Papazi

Full Text Available Hydrogen is a promising future energy source. Although the ability of green algae to produce hydrogen has long been recognized (since 1939 and several biotechnological applications have been attempted, the greatest obstacle, being the O2-sensitivity of the hydrogenase enzyme, has not yet been overcome. In the present contribution, 75 years after the first report on algal hydrogen production, taking advantage of a natural mechanism of oxygen balance, we demonstrate high hydrogen yields by lichens. Lichens have been selected as the ideal organisms in nature for hydrogen production, since they consist of a mycobiont and a photobiont in symbiosis. It has been hypothesized that the mycobiont's and photobiont's consumption of oxygen (increase of COX and AOX proteins of mitochondrial respiratory pathways and PTOX protein of chrolorespiration establishes the required anoxic conditions for the activation of the phycobiont's hydrogenase in a closed system. Our results clearly supported the above hypothesis, showing that lichens have the ability to activate appropriate bioenergetic pathways depending on the specific incubation conditions. Under light conditions, they successfully use the PSII-dependent and the PSII-independent pathways (decrease of D1 protein and parallel increase of PSaA protein to transfer electrons to hydrogenase, while under dark conditions, lichens use the PFOR enzyme and the dark fermentative pathway to supply electrons to hydrogenase. These advantages of lichen symbiosis in combination with their ability to survive in extreme environments (while in a dry state constitute them as unique and valuable hydrogen producing natural factories and pave the way for future biotechnological applications.

Lichen Symbiosis: Nature's High Yielding Machines for Induced Hydrogen Production

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Papazi, Aikaterini; Kastanaki, Elizabeth; Pirintsos, Stergios; Kotzabasis, Kiriakos

2015-01-01

Hydrogen is a promising future energy source. Although the ability of green algae to produce hydrogen has long been recognized (since 1939) and several biotechnological applications have been attempted, the greatest obstacle, being the O2-sensitivity of the hydrogenase enzyme, has not yet been overcome. In the present contribution, 75 years after the first report on algal hydrogen production, taking advantage of a natural mechanism of oxygen balance, we demonstrate high hydrogen yields by lichens. Lichens have been selected as the ideal organisms in nature for hydrogen production, since they consist of a mycobiont and a photobiont in symbiosis. It has been hypothesized that the mycobiont’s and photobiont’s consumption of oxygen (increase of COX and AOX proteins of mitochondrial respiratory pathways and PTOX protein of chrolorespiration) establishes the required anoxic conditions for the activation of the phycobiont’s hydrogenase in a closed system. Our results clearly supported the above hypothesis, showing that lichens have the ability to activate appropriate bioenergetic pathways depending on the specific incubation conditions. Under light conditions, they successfully use the PSII-dependent and the PSII-independent pathways (decrease of D1 protein and parallel increase of PSaA protein) to transfer electrons to hydrogenase, while under dark conditions, lichens use the PFOR enzyme and the dark fermentative pathway to supply electrons to hydrogenase. These advantages of lichen symbiosis in combination with their ability to survive in extreme environments (while in a dry state) constitute them as unique and valuable hydrogen producing natural factories and pave the way for future biotechnological applications. PMID:25826211

Effect of Follicular Fluid and Platelet-Activating Factor on Lactate Dehydrogenase C Expression in Human Asthenozoospermic Samples

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Tahereh Esmaeilpour

2014-01-01

Full Text Available Background: Application of follicular fluid (FF and platelet-activating factor (PAF in artificial insemination improves sperm motility. Lactate dehydrogenase C (LDH-C is a key enzyme for sperm motility. In this study, the effects of FF and PAF on the sperm motility index and LDH-C expression were investigated. Moreover, LDH-C expression was compared between asthenozoospermic and normozoospermic samples. Methods: The expression of LDH-C was examined by quantitative real-time polymerase chain reaction (q-RT PCR and western blotting after it was treated with optimized concentrations of FF and PAF in twenty asthenozoospermic samples. Also, LDH-C expression was evaluated in five normozoospermic samples. Results: Samples with 75% FF and 100 nM of PAF had an increase in their percentages of progressive and slowly motile sperms and a decrease in their percentages of non-progressive and non-motile sperms. Moreover, LDH-C mRNA transcripts were not changed following PAF and FF treatment, and LDH-C protein was detected in highly progressive motile specimens treated with FF in the asthenozoospermic samples. Furthermore, LDH-C expression was more detectable in the normal sperms. Conclusion: Our results indicated that PAF had more beneficial effects than FF on sperm motility in the asthenozoospermic samples (P=0.0001, although the LDH-C expressions of the sperms were not changed significantly in both groups. We found no association between LDH-C expression and sperm motility after FF and PAF actions. This finding, however, requires further investigation. The fact that LDH-C protein was detected in the normozoospermic, but not asthenozoospermic, samples could be cited as a reason for the infertility in these patients.

Intercalation behavior of amino acids into Zn-Al-layered double hydroxide by calcination-rehydration reaction

International Nuclear Information System (INIS)

Aisawa, Sumio; Kudo, Hiroko; Hoshi, Tomomi; Takahashi, Satoshi; Hirahara, Hidetoshi; Umetsu, Yoshio; Narita, Eiichi

2004-01-01

The intercalation of amino acids for the Zn-Al-layered double hydroxide (LDH) has been investigated by the calcination-rehydration reaction at 298K using mainly phenylalanine (Phe) as a guest amino acid. The Zn-Al oxide precursor prepared by the calcination of Zn-Al-carbonated LDH at 773K for 2h was used as the host material. The amount of Phe intercalated by the rehydration was remarkably influenced by the initial solution pH and reached ca. 2.7 times for anion exchange capacity (AEC) of the LDH at neutral and weak alkaline solutions, suggesting that Phe was intercalated as amphoteric ion form into the LDH interlayer. As Phe is intercalated for the LDH as monovalent anion in alkaline solution, the amount of Phe intercalated at pH 10.5 corresponded with AEC of the LDH. The solid products were found to have the expanded LDH structure, which confirmed that Phe was intercalated into the LDH interlayer as amphoteric ion or anion form. The basal spacing, d 003 , of the Phe/LDH was 1.58nm at pH 7.0 and 0.80nm at pH 10.5; two kinds of expansion suggested for Phe in the interlayer space as vertical (pH 7.0) and horizontal (pH 10.5) orientations. The intercalation behavior of various amino acids for the LDH was also found to be greatly influenced by the feature of the amino acid side-chain, namely, its carbon-chain length, structure and physicochemical property. In particular, α-amino acids possessing a hydrophobic or negative-charged side-chain were preferentially intercalated for the LDH

Bioactivity-guided identification and cell signaling technology to delineate the lactate dehydrogenase A inhibition effects of Spatholobus suberectus on breast cancer.

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Zhiyu Wang

Full Text Available Aerobic glycolysis is an important feature of cancer cells. In recent years, lactate dehydrogenase A (LDH-A is emerging as a novel therapeutic target for cancer treatment. Seeking LDH-A inhibitors from natural resources has been paid much attention for drug discovery. Spatholobus suberectus (SS is a common herbal medicine used in China for treating blood-stasis related diseases such as cancer. This study aims to explore the potential medicinal application of SS for LDH-A inhibition on breast cancer and to determine its bioactive compounds. We found that SS manifested apoptosis-inducing, cell cycle arresting and anti-LDH-A activities in both estrogen-dependent human MCF-7 cells and estrogen-independent MDA-MB-231 cell. Oral herbal extracts (1 g/kg/d administration attenuated tumor growth and LDH-A expression in both breast cancer xenografts. Bioactivity-guided fractionation finally identified epigallocatechin as a key compound in SS inhibiting LDH-A activity. Further studies revealed that LDH-A plays a critical role in mediating the apoptosis-induction effects of epigallocatechin. The inhibited LDH-A activities by epigallocatechin is attributed to disassociation of Hsp90 from HIF-1α and subsequent accelerated HIF-1α proteasome degradation. In vivo study also demonstrated that epigallocatechin could significantly inhibit breast cancer growth, HIF-1α/LDH-A expression and trigger apoptosis without bringing toxic effects. The preclinical study thus suggests that the potential medicinal application of SS for inhibiting cancer LDH-A activity and the possibility to consider epigallocatechin as a lead compound to develop LDH-A inhibitors. Future studies of SS for chemoprevention or chemosensitization against breast cancer are thus warranted.

Layered double hydroxide nanoparticles promote self-renewal of mouse embryonic stem cells through the PI3K signaling pathway

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Wu, Youjun; Zhu, Rongrong; Zhou, Yang; Zhang, Jun; Wang, Wenrui; Sun, Xiaoyu; Wu, Xianzheng; Cheng, Liming; Zhang, Jing; Wang, Shilong

2015-06-01

Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles have shown promising applications in directing the stem cell fate. Herein, we investigated the cellular effects of layered double hydroxide nanoparticles (LDH NPs) on mouse ESCs (mESCs) and the associated molecular mechanisms. Mg-Al-LDH NPs with an average diameter of ~100 nm were prepared by hydrothermal methods. To determine the influences of LDH NPs on mESCs, cellular cytotoxicity, self-renewal, differentiation potential, and the possible signaling pathways were explored. Evaluation of cell viability, lactate dehydrogenase release, ROS generation and apoptosis demonstrated the low cytotoxicity of LDH NPs. The alkaline phosphatase activity and the expression of pluripotency genes in mESCs were examined, which indicated that exposure to LDH NPs could support self-renewal and inhibit spontaneous differentiation of mESCs under feeder-free culture conditions. The self-renewal promotion was further proved to be independent of the leukemia inhibitory factor (LIF). Furthermore, cells treated with LDH NPs maintained the potential to differentiate into all three germ layers both in vitro and in vivo through formation of embryoid bodies and teratomas. In addition, we observed that LDH NPs initiated the activation of the PI3K/Akt pathway, while treatment with the PI3K inhibitor LY294002 could block the effects of LDH NPs on mESCs. The results confirmed that the promotion of self-renewal by LDH NPs was associated with activation of the PI3K/Akt signaling pathway. Altogether, our studies identified a new role of LDH NPs in maintaining self-renewal of mouse ES cells which could potentially be applied in stem cell research.Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles

The Evolution of Dinitrogen Fixation

International Nuclear Information System (INIS)

Broda, E.

1984-01-01

It is argued that nitrogenase originated monophyletically in obligate anaerobes similar to Clostridia. The enzyme system was later inherited, without much change, by photosynthetic bacteria, by prokaryotic plants (blue-greens) and by aerobic bacteria. The hydrogenase function of the enzyme complex preceded the nitrogenase function, and was useful in hydrogen fermentations. The consumption of ATP served to assure disposal of electrons in the form of hydrogen gas. The present need of the enzyme system, whether acting as hydrogenase or as nitrogenase, for ATP may be a relic from the period when the biosphere was still reducing. (author)

Synthesis of bio-based nanocomposites for controlled release of antimicrobial agents in food packaging

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DeGruson, Min Liu

The utilization of bio-based polymers as packaging materials has attracted great attention in both scientific and industrial areas due to the non-renewable and nondegradable nature of synthetic plastic packaging. Polyhydroxyalkanoate (PHA) is a biobased polymer with excellent film-forming and coating properties, but exhibits brittleness, insufficient gas barrier properties, and poor thermal stability. The overall goal of the project was to develop the polyhydroxyalkanoate-based bio-nanocomposite films modified by antimicrobial agents with improved mechanical and gas barrier properties, along with a controlled release rate of antimicrobial agents for the inhibition of foodborne pathogens and fungi in food. The ability for antimicrobial agents to intercalate into layered double hydroxides depended on the nature of the antimicrobial agents, such as size, spatial structure, and polarity, etc. Benzoate and gallate anions were successfully intercalated into LDH in the present study and different amounts of benzoate anion were loaded into LDH under different reaction conditions. Incorporation of nanoparticles showed no significant effect on mechanical properties of polyhydroxybutyrate (PHB) films, however, significantly increased the tensile strength and elongation at break of polyhydroxybutyrate-co-valerate (PHBV) films. The effects of type and concentration of LDH nanoparticles (unmodified LDH and LDH modified by sodium benzoate and sodium gallate) on structure and properties of PHBV films were then studied. The arrangement of LDH in the bio-nanocomposite matrices ranged from exfoliated to phase-separated depending on the type and concentration of LDH nanoparticles. Intercalated or partially exfoliated structures were obtained using modified LDH, however, only phase-separated structures were formed using unmodified LDH. The mechanical (tensile strength and elongation at break) and thermo-mechanical (storage modulus) properties were significantly improved with low

Mechanical and Morphological Properties of Poly-3-hydroxybutyrate/Poly(butyleneadipate-co-terephthalate/Layered Double Hydroxide Nanocomposites

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Yen Leng Pak

2013-01-01

Full Text Available Nanocomposites of poly-3-hydroxybutyrate/poly(butyleneadipate-co-terephthalate/layered double hydroxide (PHB/PBAT/LDH were prepared from a binary blend of PHB/PBAT and stearate-Zn3Al LDH via a solution casting method using chloroform as solvent in this study. The pristine Zn3Al LDH was synthesized from nitrate salts solution at pH 7 by using coprecipitation technique and then was modified by stearate anions surfactant via ion exchange reaction. As a result, the basal spacing of the LDH was increased from 8.77 to 24.94 Å after the modification. Intercalated nanocomposites were formed due to the presence of diffraction peak in XRD diffractograms. The infrared spectrum of stearate-Zn3Al LDH exhibited the existence of stearate anions in the synthesized Zn3Al LDH. Mechanical properties with 2 wt% stearate-Zn3Al LDH loading nanocomposites showed 56 wt% improvements in elongation at break compared to those of the blend.

Layer-by-layer self-assembly of polyimide precursor/layered double hydroxide ultrathin films

International Nuclear Information System (INIS)

Chen Dan; Huang Shu; Zhang Chao; Wang Weizhi; Liu Tianxi

2010-01-01

The layer-by-layer (LBL) self-assembly has been extensively used as a simple and effective method for the preparation of polyelectrolyte multilayer films. In this work, we utilized this unique method to prepare polyimide precursor/layered double hydroxide (LDH) ultrathin films. Well-crystallized Co-Al-CO 3 LDH and subsequent anion exchanged Co-Al-NO 3 LDH were prepared and characterized by scanning electron microscopy and X-ray diffraction (XRD). By vigorous shaking of the as-prepared Co-Al-NO 3 LDH, positively charged and exfoliated LDH nanosheets were obtained. Atomic force microscopy and XRD investigations indicated the delamination of LDH nanosheets. The precursor of polyimide, poly(amic acid) tertiary amine salt (PAS) was prepared by the polycondensation of dianhydride and diamine, and subsequent amine salt formation. By using the LBL method, heterogeneous ultrathin films of PAS and LDH were prepared. The formation of the ordered nanostructured assemblies was confirmed by the progressive enhancement of UV absorbance and the XRD results.

Synthesis of Co–Al layered double hydroxide nanoclusters as reduction nanocatalyst in aqueous media

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Daisuke Kino

2017-12-01

Full Text Available Layered double hydroxides (LDHs have attracted attention as green materials due to their catalytic ability in benign aqueous solvents. We here demonstrate the synthesis of colloidal Co–Al LDH nanoclusters with an average size of <10 nm via a facile liquid-phase reaction for the enhancement of the catalytic activity. To the best of our knowledge, the present LDH is the smallest Co–Al LDH with an extremely large surface area and stability in an aqueous solvent, forming a stable and concentrated colloidal solution as high as 40 g/L. We investigated the formation mechanism, and the catalytic activity of Co–Al LDH nanoclusters. The Co–Al LDH nanoclusters showed 47 times higher rate of the reduction of dye molecules in the aqueous media than standard Co–Al LDH particles with a micrometer size. LDH nanoclusters demonstrated here are promising green nanocatalysts for the aqueous reaction processes.

Preparation and characterization of poly(lactic acid)/ zinc-aluminium layered double hydroxide nano composites

International Nuclear Information System (INIS)

Eili Mahboobeh; Wan Mohd Zin Wan Yunus; Zobir Hossein; Mansor Ahmad; Norazowa Ibrahim

2009-01-01

Full text: Poly (lactic acid)/ stearate - zinc aluminum layered double hydroxide/ (PLA/ SZnAl LDH) nano composites were prepared via solution intercalation process using a modified ZnAl LDH. The anionic clay Zn 3 Al-NO 3 -LDH was prepared by a co-precipitation method and then modified with stearate ions by ion exchange process. Stearate-ZnAl LDH particles were then homogeneously dispersed in PLA matrix by a solution casting method. The pristine and modified ZnAl LDH was characterized by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy which suggested that the modification was successful. The XRD analysis showed that during modification of LDH, the basal spacing increased from 8.83 Angstrom to 40.1 Angstrom. The PLA/ ZnAl LDH nano composites were characterized by tensile testing and XRD. The obtained nano composites showed dramatic enhancements in elongation at break as compared to those of the pure PLA. XRD results indicated that the materials formed are nano composites. (author)

Nuclear lactate dehydrogenase modulates histone modification in human hepatocytes

Energy Technology Data Exchange (ETDEWEB)

Castonguay, Zachary; Auger, Christopher; Thomas, Sean C.; Chahma, M’hamed; Appanna, Vasu D., E-mail: vappanna@laurentian.ca

2014-11-07

Highlights: • Nuclear LDH is up-regulated under oxidative stress. • SIRT1 is co-immunoprecipitated bound to nuclear LDH. • Nuclear LDH is involved in histone deacetylation and epigenetics. - Abstract: It is becoming increasingly apparent that the nucleus harbors metabolic enzymes that affect genetic transforming events. Here, we describe a nuclear isoform of lactate dehydrogenase (nLDH) and its ability to orchestrate histone deacetylation by controlling the availability of nicotinamide adenine dinucleotide (NAD{sup +}), a key ingredient of the sirtuin-1 (SIRT1) deacetylase system. There was an increase in the expression of nLDH concomitant with the presence of hydrogen peroxide (H{sub 2}O{sub 2}) in the culture medium. Under oxidative stress, the NAD{sup +} generated by nLDH resulted in the enhanced deacetylation of histones compared to the control hepatocytes despite no discernable change in the levels of SIRT1. There appeared to be an intimate association between nLDH and SIRT1 as these two enzymes co-immunoprecipitated. The ability of nLDH to regulate epigenetic modifications by manipulating NAD{sup +} reveals an intricate link between metabolism and the processing of genetic information.

Multifunctional organic–inorganic hybrid nanoparticles and nanosheets based on chitosan derivative and layered double hydroxide: cellular uptake mechanism and application for topical ocular drug delivery

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Chi H

2017-02-01

Full Text Available Huibo Chi,1,2,* Yan Gu,1,* Tingting Xu,1 Feng Cao1 1Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, 2State Key Laboratory of Drug Delivery Technology and Pharmacokinetics, Tianjin Institute of Pharmaceutical Research Co., Ltd., Tianjin, People’s Republic of China *These authors contributed equally to this work Abstract: To study the cellular uptake mechanism of multifunctional organic–inorganic hybrid nanoparticles and nanosheets, new chitosan–glutathione–valine–valine-layered double hydroxide (CG-VV-LDH nanosheets with active targeting to peptide transporter-1 (PepT-1 were prepared, characterized and further compared with CG-VV-LDH nanoparticles. Both organic–inorganic hybrid nanoparticles and nanosheets showed a sustained release in vitro and prolonged precorneal retention time in vivo, but CG-VV-LDH nanoparticles showed superior permeability in the isolated cornea of rabbits than CG-VV-LDH nanosheets. Furthermore, results of cellular uptake on human corneal epithelial primary cells (HCEpiC and retinal pigment epithelial (ARPE-19 cells indicated that both clathrin-mediated endocytosis and active transport of PepT-1 are involved in the internalization of CG-VV-LDH nanoparticles and CG-VV-LDH nanosheets. In summary, the CG-VV-LDH nanoparticle may be a promising carrier as a topical ocular drug delivery system for the treatment of ocular diseases of mid-posterior segments, while the CG-VV-LDH nanosheet may be suitable for the treatment of ocular surface diseases. Keywords: LDH nanoparticles, LDH nanosheets, ocular drug delivery, human corneal epithelial primary cell, retinal pigment cell, ARPE-19, active targeting

Antifouling composites with self-adaptive controlled release based on an active compound intercalated into layered double hydroxides

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Yang, Miaosen; Gu, Lianghua; Yang, Bin; Wang, Li; Sun, Zhiyong; Zheng, Jiyong; Zhang, Jinwei; Hou, Jian; Lin, Cunguo

2017-12-01

This paper reports a novel method to prepare the antifouling composites with properties of self-adaptive controlled release (defined as control the release rate autonomously and adaptively according to the change of environmental conditions) by intercalation of sodium paeonolsilate (PAS) into MgAl and ZnAl layered double hydroxide (LDH) with the molar ratio (M2+/M3+) of 2:1 and 3:1, respectively. The powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) confirm the intercalation of PAS into the galleries of LDH. The controlled release behavior triggered by temperature for the PAS-LDH composites has been investigated, and the results show that the release rate of all PAS-LDH composites increases as the increase of temperature. However, the MgAl-PAS-LDH composites (Mg2Al-PAS-LDH and Mg3Al-PAS-LDH) exhibit the increased release rate of 0.21 ppm/°C from 15 to 30 °C in 3.5% NaCl solution, more than three times of the ZnAl-PAS-LDH composites (0.06 ppm/°C), owing to the confined microenvironment influenced by metal types in LDH layers. In addition, a possible diffusion-controlled process with surface diffusion, bulk diffusion and heterogeneous flat surface diffusion has been revealed via fitting four kinetic equations. Moreover, to verify the practical application of the PAS-LDH composites, a model coating denoted as Mg2Al-PAS-LDH coating was fabricated. The release result displays that the release rate increases or decreases as temperature altered at 15 and 25 °C alternately, indicating its self-adaptive controlled release behavior with temperature. Moreover, the superior resistance to the settlement of Ulva spores at 15 and 25 °C was observed for the Mg2Al-PAS-LDH coating, as a result of the controllable release of antifoulant. Therefore, this work provides a facile and effective method for the fabrication of antifouling composites with self-adaptive controlled release behavior in response to temperature, which can be used to prolong

Monitoring carcinogenesis in a case of oral squamous cell carcinoma using a panel of new metabolic blood biomarkers as liquid biopsies.

Science.gov (United States)

Grimm, Martin; Hoefert, Sebastian; Krimmel, Michael; Biegner, Thorsten; Feyen, Oliver; Teriete, Peter; Reinert, Siegmar

2016-09-01

One of the common malignant tumors of the head and neck worldwide with generally unfavorable prognosis is squamous cell carcinoma (OSCC) of the oral cavity. Early detection of primary, secondary, or recurrent OSCC by liquid biopsy tools is much needed. Twelve blood biomarkers were used for monitoring a case of OSCC suffering from precancerous oral lichen ruber planus mucosae (OLP). After curative R0 tumor resection of primary OSCC (buccal mucosa), elevated epitope detection in monocytes (EDIM)-Apo10, EDIM-transketolase-like-1 (TKTL1), squamous cell carcinoma antigen (SCC-Ag), total serum lactate dehydrogenase (LDH), and its anaerobic isoforms (LDH-4, LDH-5) decreased to normal levels. Three and six months after surgery, transformation of suspicious mucosal lesions has been accompanied with an increase of EDIM scores, total serum LDH values, and a metabolic shift from aerobic (decrease of LDH-1, LDH-2) to anaerobic (increase of LDH-4, LDH-5) conditions. Two months later, secondary OSCC was histopathologically analyzed after tissue biopsy. Cytokeratin fraction 21-1 (CYFRA 21-1), carcinoembryonic antigen (CEA), and carbohydrate antigen 19-9 (CA19-9) were not affected during the clinical course of carcinogenesis. A combination strategy using a standardized panel of established (metabolic) blood biomarkers (TKTL1, LDH, LDH isoenzymes) is worth and can be recommended among others (apoptosis resistance-related Apo10, SCC-Ag) for early detection and diagnosis of primary, secondary, and recurrent OSCC. A tandem strategy utilizing (metabolic pronounced) routine liquid biopsies with imaging techniques may enhance diagnosis of OSCC in the future. Although we demonstrated the diagnostic utility of separated liquid biopsies in our previous study cohorts, further investigations in a larger patient cohort are necessary to recommend this combination strategy (EDIM blood test, LDH value, metabolic shift of LDH isoenzymes, and others, e.g., SCC-Ag or immunophenotyping) as a

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Nesreen S. [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia); Menzel, Robert [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Bio Nano Consulting, The Gridiron Building, One Pancras Square, London N1C 4AG (United Kingdom); Wang, Yifan [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Garcia-Gallastegui, Ainara [Bio Nano Consulting, The Gridiron Building, One Pancras Square, London N1C 4AG (United Kingdom); Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N. [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia); Mokhtar, Mohamed, E-mail: mmokhtar2000@yahoo.com [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia)

2017-02-15

Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH. - Graphical abstract: CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary, two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. - Highlights: • CuAl LDH/GO and CoAl LDH/GO hybrid materials with different LDH compositions were prepared. • Hybrids were fully characterised and their catalytic efficiency over the Classic Ullman Reaction was studied. • CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) in 25 min reaction times. • GO provides a light-weight, charge complementary, two-dimensional material that interacts effectively with the 2D LDHs. • After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

Discrimination of damages depending on the types of lactic dehydrogenase isozymes in electron beam irradiation

International Nuclear Information System (INIS)

Ohta, Akishige; Matsubayashi, Takashi; Liu Xiaolan; Takizawa, Haruki.

1995-01-01

Lactate dehydrogenase (EC 1.1.1.27,LDH) was a tetrameric molecule. The five different combinations of two different polypeptide chains can be readily identified by electrophoresis and ion-exchange chromatography. Injury patterns of LDH activity following electron-beam irradiation was investigated by assaying activities of three isozymes (pig heart LDH;M 4 , rabbit muscle LDH;H 4 , chicken heart LDH;M 3 H 1 ). Following results were obtained in the electron beam irradiation to three kinds of LDH isozymes: 1) Each isozyme has respective different reactivities to the electron beam irradiation. 2) Among the isozymes, M 4 enzyme was increased its enzymatic activity by the irradiations of low-level doses. 3) For the H 4 enzymes, an increasing phenomenon of -SH group was found in the low-level doses of electron beam irradiation. (author)

Development of polymer nanocomposites based on layered double hydroxides

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Sipusic, J.

2009-05-01

Full Text Available Polymeric nanocomposites are commonly considered as systems composed of a polymeric matrix and - usually inorganic - filler. The types of nanofillers are indicated in Fig. 1. Beside wellknown layered silicate fillers, recent attention is attracted to layered double hydroxide fillers (LDH, mainly of synthetic origin. The structure of LDH is based on brucite, or magnesium hydroxide, Mg(OH2 and is illustrated in Fig. 2. The modification of LDHs is commonly done by organic anions, to increase the original interlayer distance and to improve the organophilicity of the filler, keeping in mind their final application as fillers for, usually hydrophobic, polymer matrices. We have used the modified rehydration procedure for preparing organically modified LDH. The stoichiometric quantities of Ca33Al2O6, CaO and benzoic (B (or undecenoic (U acid were mixed with water and some acetone. After long and vigorous shaking, the precipitated fillers were washed, dried and characterized. X-ray diffraction method (XRD has shown the increase of the original interlayer distance for unmodified LDH (OH–-saturated of 0.76 nm to the 1.6 nm in LDH-B or LDH-U fillers (Fig. 3. Infrared spectroscopy method (FTIR has confirmed the incorporation of benzoic anion within the filler layers (Fig. 4. For the preparation of LDH-B and LDH-U composites with polystyrene (PS, poly(methyl methacrylate (PMMA and copolymer (SMMA matrices, a two-step in situ bulk radical polymerization was selected (Table 1 for recipes, azobisisobutyronitrile as initiator, using conventional stirred tank reactor in the first step, and heated mold with the movable wall (Fig. 6 in the second step of polymerization. All the prepared composites with LDH-U fillers were macroscopically phase-separated, as was the PMMA/LDH-B composite.PS/LDH-B and SMMA/LDH-B samples were found to be transparent and were further examined for deduction of their structure (Fig. 5 and thermal properties. FTIR measurements showed that

Elevated lactate dehydrogenase activity and increased cardiovascular mortality in the arsenic-endemic areas of southwestern Taiwan

Energy Technology Data Exchange (ETDEWEB)

Liao, Ya-Tang [Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Taiwan (China); Graduate Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taiwan (China); Genomics Research Center, Academia Sinica, Taiwan (China); Chen, Chien-Jen [Graduate Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taiwan (China); Genomics Research Center, Academia Sinica, Taiwan (China); Li, Wan-Fen [Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Taiwan (China); Hsu, Ling-I [Genomics Research Center, Academia Sinica, Taiwan (China); Tsai, Li-Yu; Huang, Yeou-Lih [Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Taiwan (China); Sun, Chien-Wen [Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Taiwan (China); Chen, Wei J., E-mail: wjchen@ntu.edu.tw [Graduate Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taiwan (China); Genetic Epidemiology Core Laboratory, National Taiwan University Center for Genomic Medicine, Taiwan (China); Wang, Shu-Li, E-mail: slwang@nhri.org.tw [Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Taiwan (China); Department of Public Health, College of Public Health, China Medical University, Taichung, Taiwan (China)

2012-08-01

Arsenic ingestion has been linked to increasing global prevalence of and mortality from cardiovascular disease (CVD); arsenic can be removed from drinking water to reduce related health effects. Lactate dehydrogenase (LDH) is used for the evaluation of acute arsenic toxicity in vivo and in vitro, but it is not validated for the evaluation of long-term, chronic arsenic exposure. The present study examined the long-term effect of chronic arsenic exposure on CVD and serum LDH levels, after consideration of arsenic metabolism capacity. A total of 380 subjects from an arseniasis-endemic area and 303 from a non-endemic area of southwestern Taiwan were recruited in 2002. Various urinary arsenic species were analyzed using high-performance liquid chromatography (HPLC) and hydride generation systems. Fasting serum was used for quantitative determination of the total LDH activity. A significant dose–response relationship was observed between arsenic exposure and LDH elevation, independent of urinary arsenic profiles (P < 0.001). Furthermore, abnormal LDH elevation was associated with CVD mortality after adjustment for Framingham risk scores for 10-year CVD and arsenic exposure (hazard ratio, 3.98; 95% confidence interval, 1.07–14.81). LDH was elevated in subjects with arsenic exposure in a dose-dependent manner. LDH is a marker of arsenic toxicity associated with CVD mortality. Results of this study have important implications for use in ascertaining long-term arsenic exposure risk of CVD. -- Highlights: ► We showed that arsenic exposure was correlated with LDH elevation. ► LDH elevation was related to arsenic methylation capacity. ► Abnormal LDH elevation can be a marker of susceptibility to CVD mortality.

Elevated lactate dehydrogenase activity and increased cardiovascular mortality in the arsenic-endemic areas of southwestern Taiwan

International Nuclear Information System (INIS)

Liao, Ya-Tang; Chen, Chien-Jen; Li, Wan-Fen; Hsu, Ling-I; Tsai, Li-Yu; Huang, Yeou-Lih; Sun, Chien-Wen; Chen, Wei J.; Wang, Shu-Li

2012-01-01

Arsenic ingestion has been linked to increasing global prevalence of and mortality from cardiovascular disease (CVD); arsenic can be removed from drinking water to reduce related health effects. Lactate dehydrogenase (LDH) is used for the evaluation of acute arsenic toxicity in vivo and in vitro, but it is not validated for the evaluation of long-term, chronic arsenic exposure. The present study examined the long-term effect of chronic arsenic exposure on CVD and serum LDH levels, after consideration of arsenic metabolism capacity. A total of 380 subjects from an arseniasis-endemic area and 303 from a non-endemic area of southwestern Taiwan were recruited in 2002. Various urinary arsenic species were analyzed using high-performance liquid chromatography (HPLC) and hydride generation systems. Fasting serum was used for quantitative determination of the total LDH activity. A significant dose–response relationship was observed between arsenic exposure and LDH elevation, independent of urinary arsenic profiles (P < 0.001). Furthermore, abnormal LDH elevation was associated with CVD mortality after adjustment for Framingham risk scores for 10-year CVD and arsenic exposure (hazard ratio, 3.98; 95% confidence interval, 1.07–14.81). LDH was elevated in subjects with arsenic exposure in a dose-dependent manner. LDH is a marker of arsenic toxicity associated with CVD mortality. Results of this study have important implications for use in ascertaining long-term arsenic exposure risk of CVD. -- Highlights: ► We showed that arsenic exposure was correlated with LDH elevation. ► LDH elevation was related to arsenic methylation capacity. ► Abnormal LDH elevation can be a marker of susceptibility to CVD mortality.

Bioinspired design and assembly of layered double hydroxide/poly(vinyl alcohol) film with high mechanical performance.

Science.gov (United States)

Shu, Yingqi; Yin, Penggang; Liang, Benliang; Wang, Hao; Guo, Lin

2014-09-10

Inspired by the hierarchical structure and excellent mechanical performance of nacre, LDH nanosheets with an appropriate aspect ratio to withstand significant loads and at the same time allow for rupture under the pull-out mode were synthesized as artificial building blocks for the fabrication of nacre-like films. Multilayered PVA/LDH films with a high tensile strength and ductility were prepared for the first time by bottom-up layer-by-layer assembly of pretreated LDH nanosheets and spin-coating of PVA. The weight fraction of inorganic LDH platelets in the hybrid PVA/LDH films (wp) was controlled by changing the concentration of PVA solution applied in the spin-coating process. The resulting films revealed that the PVA/LDH hybrid films were piled close together to form a well-defined stratified structure resembling the brick-and-mortar structure of natural nacre. In the hybrid films, the content of inorganic LDH platelets was comparable to the value in nacre, up to 96.9 wt %. It could be clearly seen that the mechanical performance of the as-prepared PVA/LDH films was greatly improved by increasing the rigid building-block LDHs. The tensile strength of the 2 wt % PVA/LDH hybrid film reached a value of 169.36 MPa, thus exceeding the strength of natural nacre and reaching 4 times that of a pure PVA film. Meanwhile, its elastic modulus was comparable to that of lamellar bone.

Artifacts by marker enzyme adsorption on nanomaterials in cytotoxicity assays with tissue cultures

International Nuclear Information System (INIS)

Wohlleben, Wendel; Kolle, Susanne N; Hasenkamp, Laura-Carolin; Boeser, Alexander; Vogel, Sandra; Vacano, Bernhard von; Ravenzwaay, Ben van; Landsiedel, Robert

2011-01-01

We used precision cut lung slices (PCLS) to study the cytotoxicity of cobalt ferrite nanomaterials with and without bovine serum albumin (BSA) stabilization. Using mitochondrial activity as an indicator of cytotoxicity (WST-1 assay) increasing concentrations of cobalt ferrite nanomaterial caused increasing levels of cytotoxicity in PCLS irrespective of BSA stabilization. However, there was no increase in released lactate dehydrogenase (LDH) levels caused by BSA stabilized nanomaterial indicating concentration depended cytotoxictiy. Moreover, non-stabilized nanomaterial caused a decrease of background LDH levels in the PCLS culture supernatant confirmed by complementary methods. Direct characterization of the protein corona of extracted nanomaterial shows that the LDH decrease is due to adsorption of LDH onto the surface of the non-stabilized nanomaterial, correlated with strong agglomeration. Preincubation with serum protein blocks the adsorption of LDH and stabilizes the nanomaterial at low agglomeration. We have thus demonstrated the cytotoxicity of nanomaterials in PCLS does not correlate with disrupted membrane integrity followed by LDH release. Furthermore, we found that intracellular enzymes such as the marker enzyme LDH are able to bind onto surfaces of nanomaterial and thereby adulterate the detection of toxic effects. A replacement of BSA by LDH or a secondary LDH-on-BSA-corona were not observed, confirming earlier indications that the protein corona exchange rate are slow or vanishing on inorganic nanomaterial. Thus, the method(s) to assess nanomaterial-mediated effects have to be carefully chosen based on the cellular effect and possible nano-specific artifacts.

Importance of glycolysis and oxidative phosphorylation in advanced melanoma

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Ho Jonhan

2012-10-01

Full Text Available Abstract Serum lactate dehydrogenase (LDH is a prognostic factor for patients with stage IV melanoma. To gain insights into the biology underlying this prognostic factor, we analyzed total serum LDH, serum LDH isoenzymes, and serum lactate in up to 49 patients with metastatic melanoma. Our data demonstrate that high serum LDH is associated with a significant increase in LDH isoenzymes 3 and 4, and a decrease in LDH isoenzymes 1 and 2. Since LDH isoenzymes play a role in both glycolysis and oxidative phosphorylation (OXPHOS, we subsequently determined using tissue microarray (TMA analysis that the levels of proteins associated with mitochondrial function, lactate metabolism, and regulators of glycolysis were all elevated in advanced melanomas compared with nevic melanocytes. To investigate whether in advanced melanoma, the glycolysis and OXPHOS pathways might be linked, we determined expression of the monocarboxylate transporters (MCT 1 and 4. Analysis of a nevus-to-melanoma progression TMA revealed that MCT4, and to a lesser extend MCT1, were elevated with progression to advanced melanoma. Further analysis of human melanoma specimens using the Seahorse XF24 extracellular flux analyzer indicated that metastatic melanoma tumors derived a large fraction of energy from OXPHOS. Taken together, these findings suggest that in stage IV melanomas with normal serum LDH, glycolysis and OXPHOS may provide metabolic symbiosis within the same tumor, whereas in stage IV melanomas with high serum LDH glycolysis is the principle source of energy.

Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

International Nuclear Information System (INIS)

Qu, Jun; He, Xiaoman; Chen, Min; Hu, Huimin; Zhang, Qiwu; Liu, Xinzhong

2017-01-01

In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu_2(OH)_2CO_3) and aluminum hydroxide (Al(OH)_3) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

A comparative study of Ni-Mn layered double hydroxide/carbon composites with different morphologies for supercapacitors.

Science.gov (United States)

Li, M; Liu, F; Zhang, X B; Cheng, J P

2016-11-02

A variety of carbon materials varying from 0D to 2D, i.e. 0D nanoparticles, 1D carbon nanotubes (CNTs) and 2D reduced graphene oxide (rGO) are selected to in situ combine with Ni-Mn layered double hydroxide (LDH) to prepare electrode materials for supercapacitors. Through a simple solution method, hierarchical Ni-Mn LDH/carbon composites can be easily fabricated. A comparative study is carried out on the sandwich-like LDH/rGO, flower-like LDH/carbon black, turbostratic-structured LDH/CNTs and ternary LDH/CNTs/rGO for their structure, morphology, porous properties and electrochemical performances. The results show that the ternary Ni-Mn LDH/CNTs/rGO composite yields the highest specific capacitance of 1268 F g -1 in 2 M KOH electrolyte and a long lifespan, exhibiting great potential for supercapacitor applications. Meanwhile, investigation on the influence of the cation species of MOH (M = Li + , Na + or K + ) and the alkali concentration of the KOH electrolyte illustrates that increasing the concentration of the KOH electrolyte can benefit the capacitive performance of the electrode and that NaOH shows great advantages as an electrolyte for the Ni-Mn LDH/CNTs/rGO electrode due to its high capacitance and small resistance.

Anticancer Drug-Incorporated Layered Double Hydroxide Nanohybrids and Their Enhanced Anticancer Therapeutic Efficacy in Combination Cancer Treatment

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Tae-Hyun Kim

2014-01-01

Full Text Available Objective. Layered double hydroxide (LDH nanoparticles have been studied as cellular delivery carriers for anionic anticancer agents. As MTX and 5-FU are clinically utilized anticancer drugs in combination therapy, we aimed to enhance the therapeutic performance with the help of LDH nanoparticles. Method. Anticancer drugs, MTX and 5-FU, and their combination, were incorporated into LDH by reconstruction method. Simply, LDHs were thermally pretreated at 400°C, and then reacted with drug solution to simultaneously form drug-incorporated LDH. Thus prepared MTX/LDH (ML, 5-FU/LDH (FL, and (MTX + 5-FU/LDH (MFL nanohybrids were characterized by X-ray diffractometer, scanning electron microscopy, infrared spectroscopy, thermal analysis, zeta potential measurement, dynamic light scattering, and so forth. The nanohybrids were administrated to the human cervical adenocarcinoma, HeLa cells, in concentration-dependent manner, comparing with drug itself to verify the enhanced therapeutic efficacy. Conclusion. All the nanohybrids successfully accommodated intended drug molecules in their house-of-card-like structures during reconstruction reaction. It was found that the anticancer efficacy of MFL nanohybrid was higher than other nanohybrids, free drugs, or their mixtures, which means the multidrug-incorporated LDH nanohybrids could be potential drug delivery carriers for efficient cancer treatment via combination therapy.

Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

Energy Technology Data Exchange (ETDEWEB)

Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Hu, Huimin [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 China (China)

2017-04-15

In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu{sub 2}(OH){sub 2}CO{sub 3}) and aluminum hydroxide (Al(OH){sub 3}) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

Synthesis and characterization of Zn-Ti layered double hydroxide intercalated with cinnamic acid for cosmetic application

Science.gov (United States)

Li, Yong; Tang, Liping; Ma, Xinxu; Wang, Xinrui; Zhou, Wei; Bai, Dongsheng

2017-08-01

The use of sunscreen is recently growing and their efficacy and safety must be taken into account since they are applied on the skin frequently. In this work, an organic ultraviolet (UV) ray absorbent, cinnamic acid (CA) was intercalated into Zn-Ti layered double hydroxide (LDH) by anion-exchange reaction. ZnTi-CA-LDH, a new type of host-guest UV-blocking material has been synthesized. Detailed structural and surface morphology of ZnTi-CA-LDH were characterized by XRD, FT-IR, SEM and TEM. ZnTi-CA-LDH exhibits a superior UV blocking ability compared to pure CA and ZnTi-CO3-LDH. The thermal stability of the intercalated ZnTi-CA-LDH was investigated by TG-DTA, which showed that the thermostability of CA was markedly enhanced after intercalation into ZnTi-CO3-LDH. The EPR data showed greatly decreased photocatalytic activity compared to common inorganic UV blocking agents TiO2 and ZnO. Furthermore, the sample was formulated in a sunscreen cream to study the matrix protective effect towards UV rays.

Intercalation of papain enzyme into hydrotalcite type layered double hydroxide

Science.gov (United States)

Zou, N.; Plank, J.

2012-09-01

Intercalation of proteolytic enzyme papain into hydrotalcite type LDH structure was achieved by controlled co-precipitation at pH=9.0 in the presence of papain. Characterization of the MgAl-papain-LDH phase was carried out using X-ray powder diffraction (XRD), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). According to XRD, papain was successfully intercalated. The d-value for the basal spacing of MgAl-papain-LDH was found at ˜5.3 nm. Consequently, original papain (hydrodynamic diameter ˜7.2 nm) attains a compressed conformation during intercalation.Formation of MgAl-papain-LDH was confirmed by elemental analysis and transmission electron microscopy (TEM). Under SEM, MgAl-papain-LDH phases appear as nanothin platelets which are intergrown to flower-like aggregates. Steric size and activity of the enzyme was retained after deintercalation from MgAl-LDH framework, as was evidenced by light scattering and UV/vis measurements. Thus, papain is not denatured during intercalation, and LDH is a suitable host structure which can provide a time-controlled release of the biomolecule.

Layered double hydroxide nanosheet as a two-dimensional support of dense platinum nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Yu, Hyo Gyoung; Cho, Se Hee; Ji, Hong Geun [H and A PharmaChem, R and D center, Bucheon (Korea, Republic of); Lee, Jong Hyeon [Dept. of Chemistry, The Catholic University of Korea, Bucheon (Korea, Republic of)

2017-02-15

Transition metal nanoparticles (NPs) with a narrow size distribution have been intensively synthesized on various solid supports for anti-agglomeration, and high catalytic activity and selectivity. Layered double hydroxides (LDH) are currently attracting intense interest in the field of heterogeneous catalysis as catalyst supports. In order to obtain a well-crystallized LDH nanosheet, the as-synthesize d carbonate form of LDH was hydrothermally treated according to a reported procedure, and further reacted by anion-exchange with an aqueous solution of NaNO{sub 3} and acetate buffer to give the nitrate form of LDH. Dense and uniform Pt NPs were synthesized on the exfoliated LDH nanosheets through precursor exchange and thermal reduction of the precursor ions. In this nanocomposite, the Pt Nps were uniformly grown on the surface of the LDH nano sheet and the average size of Pt Nps was 2nm.

In Situ Formation of Decavanadate-Intercalated Layered Double Hydroxide Films on AA2024 and their Anti-Corrosive Properties when Combined with Hybrid Sol Gel Films

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Junsheng Wu

2017-04-01

Full Text Available A layered double hydroxide (LDH film was formed in situ on aluminum alloy 2024 through a urea hydrolysis method, and a decavanadate-intercalated LDH (LDH-V film fabricated through the dip coating method. The microstructural and morphological characteristics were investigated by scanning electron microscopy (SEM. The corrosion-resistant performance was analyzed by electrochemical impedance spectroscopy (EIS, scanning electrochemical microscopy (SECM, and a salt-spray test (SST.The SEM results showed that a complete and defect-free surface was formed on the LDH-VS film. The anticorrosion results revealed that the LDH-VS film had better corrosion-resistant properties than the LDH-S film, especially long-term corrosion resistance. The mechanism of corrosion protection was proposed to consist of the self-healing effect of the decavanadate intercalation and the shielding effect of the sol-gel film.

Effect of rare earth ion Ce3+ on the lactate dehydrogenase isozyme patterns of six mouse organs

International Nuclear Information System (INIS)

Jiangyan, L.; Guojun, S.; Hengyi, L.; Yinhua, L.; Ting, W.; Yansheng, Y.

1998-01-01

Full text: Effect of rare earth ion Ce 3+ on the lactate dehydrogenase (LDH) isozyme patterns of six organs of mouse (heart, liver, kidney, muscle, stomach) were investigated by utilizing polyacrylamide gel electrophoresis (PAGE) methods. The results indicated: Ce 3+ not only can make some LDH bands disappear but also can induce some new bands. Under the action of Ce 3+ , the shades of some LDH bands were changed and the shade variations were different from organ to organ. In the muscle, it appeared the shade of LDH bands was related to the rare earth concentration in the feed. Rare earth can affect the muscle LDH patterns widely and apparently

Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin-Benson-Bassham cycle.

Science.gov (United States)

Nagy, Valéria; Podmaniczki, Anna; Vidal-Meireles, André; Tengölics, Roland; Kovács, László; Rákhely, Gábor; Scoma, Alberto; Tóth, Szilvia Z

2018-01-01

Photobiological H 2 production has the potential of becoming a carbon-free renewable energy source, because upon the combustion of H 2 , only water is produced. The [Fe-Fe]-type hydrogenases of green algae are highly active, although extremely O 2 -sensitive. Sulphur deprivation is a common way to induce H 2 production, which, however, relies substantially on organic substrates and imposes a severe stress effect resulting in the degradation of the photosynthetic apparatus. We report on the establishment of an alternative H 2 production method by green algae that is based on a short anaerobic induction, keeping the Calvin-Benson-Bassham cycle inactive by substrate limitation and preserving hydrogenase activity by applying a simple catalyst to remove the evolved O 2 . Cultures remain photosynthetically active for several days, with the electrons feeding the hydrogenases mostly derived from water. The amount of H 2 produced is higher as compared to the sulphur-deprivation procedure and the process is photoautotrophic. Our protocol demonstrates that it is possible to sustainably use algal cells as whole-cell catalysts for H 2 production, which enables industrial application of algal biohydrogen production.

Hydrogen production of Enterobacter aerogenes altered by extracellular and intracellular redox states

Energy Technology Data Exchange (ETDEWEB)

Nakashimada, Y.; Rachman, M.A.; Kakizono, T.; Nishio, N. [Hiroshima University, Higashi-Hiroshima (Japan). Graduate School of Advanced Sciences of Matter, Department of Molecular Biotechnology

2002-12-01

Enterobacter aerogenes HU-101, tested for its hydrogen production in batch cultures on various substrates, produced the highest amount of hydrogen when the substrate was glycerol. The yield of hydrogen is a function of the degree to which the substrates are reduced. To examine the effect of intracellular redox state on hydrogen yield, glucose-limiting chemostat cultures were carried out at various pH using strain HU-101 and its mutant AY-2. For both strains, the molar yield and the production rate of hydrogen and the hydrogenase activity in the cell-free extract were optimal at the culture pH of 6.3. The highest NADH/NAD ratio in both strains was also observed at pH 6.3, at which the ratio in AY-2 was more than two-fold that of HU-101. Furthermore, NAD(P)H-dependent hydrogen formation was observed in the cell-free extract of AY-2, and hydrogenase activity was found not in the cytoplasmic but in the cell membrane fraction, suggesting that a high intracellular redox state, that is a high NADH/NAD ratio, would accelerate hydrogen production by driving membrane-bound NAD(P)H-dependent hydrogenase. (author)

The generation of molecular hydrogen by cyanobacteria. Die Gewinnung von molekularem Wasserstoff durch Cyanobakterien

Energy Technology Data Exchange (ETDEWEB)

Kentemich, T.; Haverkamp, G.; Bothe, H. (Koeln Univ. (Germany, F.R.). Botanisches Inst.)

1990-01-01

Currently there is renewed interest in projects on solar-energy conversion by microorganisms. Among all organisms, cyanobacteria are first choice for such projects. Hydrogen production by cyanobacteria is light-dependent and catalyzed by the enzyme complex nitrogenase which concomitantly catalyzes the reduction of N{sub 2} to ammonia. The cyanobacterium Anabaena variabilis can express an alternative, vanadium-containing nitrogenase which produces more hydrogen than the conventional, molybdenum-containing enzyme. In intact cells, most of the H{sub 2} produced by nitrogenase is immediatley reutilized by the hydrogenase enzymes. Maximal hydrogen production requires the genetic blockage of H{sub 2} utilization by the hydrogenases. (orig.).

Tailoring surface properties and structure of layered double hydroxides using silanes with different number of functional groups

International Nuclear Information System (INIS)

Tao, Qi; He, Hongping; Li, Tian; Frost, Ray L.; Zhang, Dan; He, Zisen

2014-01-01

Four silanes, trimethylchlorosilane (TMCS), dimethyldiethoxylsilane (DMDES), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS), were adopted to graft layered double hydroxides (LDH) via an induced hydrolysis silylation method (IHS). Fourier transform infrared spectra (FTIR) and 29 Si MAS nuclear magnetic resonance spectra ( 29 Si MAS NMR) indicated that APTES and TEOS can be grafted onto LDH surfaces via condensation with hydroxyl groups of LDH, while TMCS and DMDES could only be adsorbed on the LDH surface with a small quantity. A combination of X-ray diffraction patterns (XRD) and 29 Si MAS NMR spectra showed that silanes were exclusively present in the external surface and had little influence on the long range order of LDH. The surfactant intercalation experiment indicated that the adsorbed and/or grafted silane could not fix the interlamellar spacing of the LDH. However, they will form crosslink between the particles and affect the further surfactant intercalation in the silylated samples. The replacement of water by ethanol in the tactoids and/or aggregations and the polysiloxane oligomers formed during silylation procedure can dramatically increase the value of BET surface area (S BET ) and total pore volumes (V p ) of the products. - Graphical abstract: The replacement of water by ethanol in the tactoids and aggregations of LDHs, and the polysiloxane oligomers formed during silylation process can dramatically increase the BET surface area (S BET ) and the total pore volume (V p ) of the silylated products. - Highlights: • Silanes with multifunctional groups were grafted onto LDH surface in C 2 H 5 OH medium. • The number of hydrolysable groups in silanes affects the structure of grafted LDH. • Replacement of H 2 O by C 2 H 5 OH in aggregations increases S BET and V p of grafted LDH. • Polysiloxane oligomers contribute to the increase of S BET and V p of grafted LDH

Clinical value of jointly detection serum lactate dehydrogenase/pleural fluid adenosine deaminase and pleural fluid carcinoembryonic antigen in the identification of malignant pleural effusion.

Science.gov (United States)

Zhang, Fan; Hu, Lijuan; Wang, Junjun; Chen, Jian; Chen, Jie; Wang, Yumin

2017-09-01

Limited data are available for the diagnostic value, and for the diagnostic sensitivity and specificity of joint detection of serum lactate dehydrogenase (sLDH)/pleural fluid adenosine deaminase (pADA) and pleural fluid carcinoembryonic antigen (pCEA) in malignant pleural effusion (MPE). We collected 987 pleural effusion specimens (of which 318 were malignant pleural effusion, 374 were tubercular pleural effusion, and 295 were parapneumonic effusion specimens) from the First Affiliated Hospital of Wenzhou Medical University from July 2012 to March 2016. The pADA, sLDH, pleural fluid LDH (pLDH), serum C-reactive protein (sCRP), pleural fluid protein, pCEA, white blood cell (WBC), and red blood cell (RBC) were analyzed, and the clinical data of each group were collected for statistical analysis. The level of sLDH/pADA, pCEA, and RBC from the MPE group was markedly higher than the tuberculosis pleural effusion (TB) group (Mann-Whitney U=28422.000, 9278.000, 30518, P=.000, .000, .000) and the parapneumonic pleural fluid group (Mann-Whitney U=5972.500, 7113.000, 36750.500, P=.000, .000, .000). The receiver operating characteristic curve ROC showed that the area under the ROC curve (AUC) (=0.924, 0.841) of pCEA and sLDH/pADA (cutoff=4.9, 10.6) were significantly higher than other markers for the diagnosis of MPE. Thus, joint detection of pCEA and sLDH/pADA suggested that the sensitivity, specificity, and AUC was 0.94, 81.70, and 94.32 at the cutoff 0.16 and diagnostic performance was higher than pCEA or sLDH/pADA. Joint detection of sLDH/pADA and pCEA can be used as a good indicator for the identification of benign and MPE with higher sensitivity and specificity than pCEA or sLDH/pADA. © 2016 Wiley Periodicals, Inc.

Expression, purification, crystallization and preliminary X-ray crystallographic analysis of l-lactate dehydrogenase and its H171C mutant from Bacillus subtilis

International Nuclear Information System (INIS)

Zhang, Yanfeng; Gao, Xiaoli

2011-01-01

Recombinant wild-type l-lactate dehydrogenase from B. subtilis (BsLDH) was cocrystallized with fructose 1,6-bisphosphate and NAD + and the crystal diffracted to 2.38 Å resolution. The H171C mutant of BsLDH was also crystallized as the apoenzyme and in complex with NAD + and the crystals diffracted to 2.20 and 2.49 Å, respectively. All crystals belonged to space group P3. l-Lactate dehydrogenase (LDH) is an important enzyme involved in the last step of glycolysis that catalyzes the reversible conversion of pyruvate to l-lactate with the simultaneous oxidation of NADH to NAD + . In this study, wild-type LDH from Bacillus subtilis (BsLDH-WT) and the H171C mutant (BsLDH-H171C) were expressed in Escherichia coli and purified to near-homogeneity. BsLDH-WT was crystallized in the presence of fructose 1,6-bisphosphate (FBP) and NAD + and the crystal diffracted to 2.38 Å resolution. The crystal belonged to space group P3, with unit-cell parameters a = b = 171.04, c = 96.27 Å. BsLDH-H171C was also crystallized as the apoenzyme and in complex with NAD + , and data sets were collected to 2.20 and 2.49 Å resolution, respectively. Both BsLDH-H171C crystals belonged to space group P3, with unit-cell parameters a = b = 133.41, c = 99.34 Å and a = b = 133.43, c = 99.09 Å, respectively. Tetramers were observed in the asymmetric units of all three crystals

Preparation and regulating cell adhesion of anion-exchangeable layered double hydroxide micropatterned arrays.

Science.gov (United States)

Yao, Feng; Hu, Hao; Xu, Sailong; Huo, Ruijie; Zhao, Zhiping; Zhang, Fazhi; Xu, Fujian

2015-02-25

We describe a reliable preparation of MgAl-layered double hydroxide (MgAl-LDH) micropatterned arrays on gold substrate by combining SO3(-)-terminated self-assembly monolayer and photolithography. The synthesis route is readily extended to prepare LDH arrays on the SO3(-)-terminated polymer-bonded glass substrate amenable for cell imaging. The anion-exchangeable MgAl-LDH micropattern can act both as bioadhesive region for selective cell adhesion and as nanocarrier for drug molecules to regulate cell behaviors. Quantitative analysis of cell adhesion shows that selective HepG2 cell adhesion and spreading are promoted by the micropatterned MgAl-LDH, and also suppressed by methotrexate drug released from the LDH interlayer galleries.

Synthesis and characterization of laurate-intercalated Mg–Al layered double hydroxide prepared by coprecipitation

DEFF Research Database (Denmark)

Gerds, Nathalie Christiane; Katiyar, Vimal; Koch, Christian Bender

2012-01-01

Effective utilization of layered double hydroxides (LDH) for industrial applications requires the synthesis of pure and well-defined LDH phases. In the present study, dodecanoate (laurate) anions were intercalated into Mg–Al-layered double hydroxide (LDH-C12) by coprecipitation in the presence of...

Facile synthesis of deoxycholate intercalated layered double hydroxide nanohybrids via a coassembly process

International Nuclear Information System (INIS)

Wu, Xiaowen; Wang, Shuang; Du, Na; Zhang, Renjie; Hou, Wanguo

2013-01-01

In this paper, we describe a synthesis strategy of deoxycholate (DC) intercalated layered double hydroxide (LDH) nanohybrids via a coassembly method at room temperature. For this strategy, LDH particles were delaminated to well-dispersed 2D nanosheets in formamide, and the resulting LDH nanosheets were then coassembled with DC anions into the DC intercalated LDH (DC-LDH) nanohybrids. The so-synthesized nanohybrids were characterized by XRD, TEM, FT-IR, elemental analyses and TG-DSC. It was found that the loading amount of DC in the nanohybrids could be easily controlled by changing the ratio of DC to LDH. In addition, the nanohybrids have similar characteristics with the DC-LDH nanohybrids synthesized by the hydrothermal method, including their DC loading, crystal structure, morphology and thermal gravimetric behavior. However, this strategy exhibited the advantages of short reaction time and mild experimental conditions compared with the hydrothermal method. - Graphical abstract: Deoxycholate intercalated layered double hydroxide nanohybrids were successfully synthesized via a coassembly strategy. In this strategy, the interlayer spaces of LDHs can be efficiently used for the intercalation of guest species. - Highlights: • Deoxycholate intercalated layered double hydroxide nanohybrids were synthesized via a coassembly strategy. • This strategy exhibited the advantages of short time and mild conditions. • This strategy can enable organic species to be readily intercalated into the LDH galleries

Synthesis, Characterization, and In Vitro Drug Delivery Capabilities of (Zn, Al-Based Layered Double Hydroxide Nanoparticles

Directory of Open Access Journals (Sweden)

Vinay J. Nagaraj

2015-01-01

Full Text Available There is an urgent need for the development of alternative strategies for effective drug delivery to improve the outcome of patients suffering from deadly diseases such as cancer. Nanoparticles, in particular layered double hydroxide (LDH nanoparticles, have great potential as nanocarriers of chemotherapeutic molecules. In this study, we synthesized (Zn, Al-LDH nanoparticles and report their enhanced pH-dependent stability in comparison to the commonly used (Mg, Al-LDH nanoparticles. Fluorescein isothiocyanate (FITC and valproate (VP were intercalated into (Zn, Al-LDH nanoparticles to study cellular uptake, biocompatibility, and drug delivery capabilities using cultured pancreatic adenocarcinoma BxPC3 cells. Fluorescence measurements indicated that FITC-intercalated LDH nanoparticles showed a greater degree of energy-dependent uptake rather than passive uptake by BxPC3 cells, especially at high concentrations of nanoparticles. Tetrazolium-based colorimetric assays indicated that BxPC3 cells treated with VP-intercalated LDH nanoparticles showed a significant reduction in cell viability along with about 30-fold reduction in IC50 compared to the drug alone. In contrast, the non-drug-intercalated LDH nanoparticles did not affect the cell viability indicating very low innate cytotoxicity. Our research indicates that the superior properties of (Zn, Al-LDH nanoparticles make them ideal candidates for further development as in vivo chemotherapy drug delivery agents.

Intercalation of cellulase enzyme into a hydrotalcite layer structure

Science.gov (United States)

Zou, N.; Plank, J.

2015-01-01

A new inorganic-organic hybrid material whereby cellulase enzyme is incorporated into a hydrotalcite type layered double hydroxide (LDH) structure is reported. The Mg2Al-cellulase-LDH was synthesized via co-precipitation from Mg/Al nitrate at pH=9.6. Characterization was performed using X-ray powder diffraction (XRD), small angle X-ray scattering (SAXS), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). From XRD and SAXS measurements, a d-value of ~5.0 nm was identified for the basal spacing of the Mg2Al-cellulase-LDH. Consequently, the cellulase enzyme (hydrodynamic diameter ~6.6 nm) attains a slightly compressed conformation when intercalated. Formation of the LDH hybrid was also confirmed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mg2Al-cellulase-LDH phases appear as ~20 nm thin foils which are intergrown to flower-like aggregates. Activity of the enzyme was retained after deintercalation from the Mg2Al-LDH framework using anion exchange. Accordingly, cellulase is not denatured during the intercalation process, and LDH presents a suitable host structure for time-controlled release of the biomolecule.

Cloning and Polymorphisms of Yak Lactate Dehydrogenase b Gene

Directory of Open Access Journals (Sweden)

Yaou Xu

2013-06-01

Full Text Available The main objective of this work was to study the unique polymorphisms of the lactate dehydrogenase-1 (LDH1 gene in yak (Bos grunniens. Native polyacrylamide gel electrophoresis revealed three phenotypes of LDH1 (a tetramer of H subunit in yak heart and longissimus muscle extracts. The corresponding gene, ldhb, encoding H subunits of three LDH1 phenotypes was obtained by RT-PCR. A total of six nucleotide differences were detected in yak ldhb compared with that of cattle, of which five mutations cause amino acid substitutions. Sequence analysis shows that the G896A and C689A, mutations of ldhb gene, result in alterations of differently charged amino acids, and create the three phenotypes (F, M, and S of yak LDH1. Molecular modeling of the H subunit of LDH indicates that the substituted amino acids are not located within NAD+ or substrate binding sites. PCR-RFLP examination of G896A mutation demonstrated that most LDH1-F samples are actually heterozygote at this site. These results help to elucidate the molecular basis and genetic characteristic of the three unique LDH1 phenotypes in yak.

Prognostic Significance of Blood, Serum, and Ascites Parameters in Patients with Malignant Peritoneal Mesothelioma or Peritoneal Carcinomatosis.

Science.gov (United States)

Su, Shan-Shan; Zheng, Guo-Qi; Yin, Wen-Jie; Liang, Yu-Fei; Liu, Ying-Ying; Song, Hui; Sun, Ning-Ning; Yang, Yu-Xin

2018-01-01

To determine effects of the biochemical and cytological properties of blood, serum, and ascites on survival of patients with malignant peritoneal effusion (MPeE), including malignant peritoneal mesothelioma (MPeM) and peritoneal carcinomatosis (PC), we conducted a retrospective study of patients with MPeE and healthy controls. Potential prognostic factors were identified as follows: age, sex, blood neutrophil-to-lymphocyte ratio (NLR), serum parameters, ascites parameters, serum-ascites albumin gradient, and the ascites-serum LDH ratio. Compared to those of the control group, serum albumin levels were significantly lower, and the NLR and serum LDH levels were significantly higher in the MPeE group. Overall survival (OS) was longer in patients with MPeM compared to that in patients with PC. Compared with patients in the MPeM, patients with PC had higher NLRs, ascites glucose levels, serum-ascites albumin gradients, and serum LDH levels. In contrast, their ascites albumin levels and ascites-serum LDH ratios were lower. Univariate analyses indicated that the NLR, serum LDH levels, ascites LDH levels, ascites coenocyte levels, and the ascites coenocyte-to-monocyte ratios affected the OS. Multivariate analyses identified only serum and ascites LDH levels as independent prognostic factors.

Fragment growing and linking lead to novel nanomolar lactate dehydrogenase inhibitors.

Science.gov (United States)

Kohlmann, Anna; Zech, Stephan G; Li, Feng; Zhou, Tianjun; Squillace, Rachel M; Commodore, Lois; Greenfield, Matthew T; Lu, Xiaohui; Miller, David P; Huang, Wei-Sheng; Qi, Jiwei; Thomas, R Mathew; Wang, Yihan; Zhang, Sen; Dodd, Rory; Liu, Shuangying; Xu, Rongsong; Xu, Yongjin; Miret, Juan J; Rivera, Victor; Clackson, Tim; Shakespeare, William C; Zhu, Xiaotian; Dalgarno, David C

2013-02-14

Lactate dehydrogenase A (LDH-A) catalyzes the interconversion of lactate and pyruvate in the glycolysis pathway. Cancer cells rely heavily on glycolysis instead of oxidative phosphorylation to generate ATP, a phenomenon known as the Warburg effect. The inhibition of LDH-A by small molecules is therefore of interest for potential cancer treatments. We describe the identification and optimization of LDH-A inhibitors by fragment-based drug discovery. We applied ligand based NMR screening to identify low affinity fragments binding to LDH-A. The dissociation constants (K(d)) and enzyme inhibition (IC(50)) of fragment hits were measured by surface plasmon resonance (SPR) and enzyme assays, respectively. The binding modes of selected fragments were investigated by X-ray crystallography. Fragment growing and linking, followed by chemical optimization, resulted in nanomolar LDH-A inhibitors that demonstrated stoichiometric binding to LDH-A. Selected molecules inhibited lactate production in cells, suggesting target-specific inhibition in cancer cell lines.

Zn-Al Layered Double Hydroxide: Synthesis and Optical Properties

International Nuclear Information System (INIS)

Abdullah Ahmed Ali Ahmed; Zainal Abidin Talib

2011-01-01

Zn-Al-NO 3 -LDH was prepared by co-precipitation method at constant pH 7 and ratio of Zn/ Al=4. Thermal treatment was performed for LDH at various temperatures. The Powder XRD patterns showed stability in structure of LDH samples below 200 degree Celsius. Infrared spectra of samples showed the characteristic peaks of LDH and the changes of these peaks after thermal treatment above 150 degree Celsius. The energy gaps of the samples were found by diffuse reflectance spectroscopy which showed more than one energy gaps at sintered temperatures less than 200 degree Celsius. These energy gaps were assigned to the presence of NO 3 - in interlayer of LDH. At sintered temperature of 200 degree Celsius and above, the LDH samples have one energy gap which was around 3.3 eV. The photo catalytic activity increased due to ZnO crystal size increases by increasing of the sintered temperature of samples.(author)

Nickel-cobalt layered double hydroxide anchored zinc oxide nanowires grown on carbon fiber cloth for high-performance flexible pseudocapacitive energy storage devices

KAUST Repository

Shakir, Imran; Shahid, Muhammad; Rana, Usman Ali; Nashef, Inas M Al; Hussain, Rafaqat

2014-01-01

Nickel-cobalt layered double hydroxide (Ni-Co LDH) nanoflakes-ZnO nanowires hybrid array has been directly synthesized on a carbon cloth substrate by a facile cost-effective two-step hydrothermal route. As electrode materials for flexible pseudocapacitors, Ni-Co LDH nanoflakes-ZnO nanowires hybrid array exhibits a significantly enhanced specific capacitance of 1927 Fg-1, which is a ∼1.8 time greater than pristine Ni-Co LDH nanoflakes. The synthesized Ni-Co LDH nanoflakes-ZnO nanowires hybrid array shows a maximum energy density of 45.55 Whkg-1 at a power density of 46.15 kWkg -1, which is 35% higher than the pristine Ni-Co LDH nanoflakes electrode. Moreover, Ni-Co LDH nanoflakes-ZnO nanowires hybrid array exhibit excellent excellent rate capability (80.3% capacity retention at 30 Ag -1) and cycling stability (only 3.98% loss after 3000 cycles), due to the significantly improved faradaic redox reaction. © 2014 Elsevier Ltd.

Three-dimensional porous MXene/layered double hydroxide composite for high performance supercapacitors

Science.gov (United States)

Wang, Ya; Dou, Hui; Wang, Jie; Ding, Bing; Xu, Yunling; Chang, Zhi; Hao, Xiaodong

2016-09-01

In this work, an exfoliated MXene (e-MXene) nanosheets/nickel-aluminum layered double hydroxide (MXene/LDH) composite as supercapacitor electrode material is fabricated by in situ growth of LDH on e-MXene substrate. The LDH platelets homogeneously grown on the surface of the e-MXene sheets construct a three-dimensional (3D) porous structure, which not only leads to high active sites exposure of LDH and facile liquid electrolyte penetration, but also alleviates the volume change of LDH during the charge/discharge process. Meanwhile, the e -MXene substrate forms a conductive network to facilitate the electron transport of active material. The optimized MXene/LDH composite exhibits a high specific capacitance of 1061 F g-1 at a current density of 1 A g-1, excellent capacitance retention of 70% after 4000 cycle tests at a current density of 4 A g-1 and a good rate capability with 556 F g-1 retention at 10 A g-1.

The Adsorption of Dextranase onto Mg/Fe-Layered Double Hydroxide: Insight into the Immobilization

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Yi Ding

2018-03-01

Full Text Available We report the adsorption of dextranase on a Mg/Fe-layered double hydroxide (Mg/Fe-LDH. We focused the effects of different buffers, pH, and amino acids. The Mg/Fe-LDH was synthesized, and adsorption experiments were performed to investigate the effects. The maximum adsorption occurred in pH 7.0 4-(2-hydroxyethyl-1-piperazineethanesulfonic acid (HEPES buffer, and the maximum dextranase adsorption uptake was 1.38 mg/g (416.67 U/mg; histidine and phenylalanine could affect the adsorption. A histidine tag could be added to the protein to increase the adsorption significantly. The performance features and mechanism were investigated with X-ray diffraction patterns (XRD and Fourier transform infrared spectra (FTIR. The protein could affect the crystal structure of LDH, and the enzyme was adsorbed on the LDH surface. The main interactions between the protein and LDH were electrostatic and hydrophobic. Histidine and phenylalanine could significantly affect the adsorption. The hexagonal morphology of LDH was not affected after adsorption.

Nickel-cobalt layered double hydroxide anchored zinc oxide nanowires grown on carbon fiber cloth for high-performance flexible pseudocapacitive energy storage devices

KAUST Repository

Shakir, Imran

2014-05-01

Nickel-cobalt layered double hydroxide (Ni-Co LDH) nanoflakes-ZnO nanowires hybrid array has been directly synthesized on a carbon cloth substrate by a facile cost-effective two-step hydrothermal route. As electrode materials for flexible pseudocapacitors, Ni-Co LDH nanoflakes-ZnO nanowires hybrid array exhibits a significantly enhanced specific capacitance of 1927 Fg-1, which is a ∼1.8 time greater than pristine Ni-Co LDH nanoflakes. The synthesized Ni-Co LDH nanoflakes-ZnO nanowires hybrid array shows a maximum energy density of 45.55 Whkg-1 at a power density of 46.15 kWkg -1, which is 35% higher than the pristine Ni-Co LDH nanoflakes electrode. Moreover, Ni-Co LDH nanoflakes-ZnO nanowires hybrid array exhibit excellent excellent rate capability (80.3% capacity retention at 30 Ag -1) and cycling stability (only 3.98% loss after 3000 cycles), due to the significantly improved faradaic redox reaction. © 2014 Elsevier Ltd.

Protein (Cyanobacteria): 515868638 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available ... hydrogenase nickel incorporation protein HypA Nodosilinea nodulosa MHETDMTKALILTVRDWWEAQPGQPAIEKVHLTVGKFTC... WP_017299262.1 ... 1117:21745 ... 1150:31644 1301283:50549 ... 1120752:1645 416001:1645 ...

Production of bioplastics and hydrogen gas by photosynthetic microorganisms

Science.gov (United States)

Yasuo, Asada; Masato, Miyake; Jun, Miyake

1998-03-01

Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium, Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilic Synechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes from Alcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted. In vitro and in vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation of Synechococcus PCC7942 with the hydrogenase gene from Clostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture of Rhodobacter and Clostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium, Rhodobacter sphaeroides RV. A mutant acquired by

Mechanical and Morphological Properties of Poly-3-hydroxybutyrate/Poly(butyleneadipate-co-terephthalate)/Layered Double Hydroxide Nanocomposites

OpenAIRE

Pak, Yen Leng; Bin Ahmad, Mansor; Shameli, Kamyar; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Zainuddin, Norhazlin

2013-01-01

Nanocomposites of poly-3-hydroxybutyrate/poly(butyleneadipate-co-terephthalate)/layered double hydroxide (PHB/PBAT/LDH) were prepared from a binary blend of PHB/PBAT and stearate-Zn3Al LDH via a solution casting method using chloroform as solvent in this study. The pristine Zn3Al LDH was synthesized from nitrate salts solution at pH 7 by using coprecipitation technique and then was modified by stearate anions surfactant via ion exchange reaction. As a result, the basal spacing of the LDH was ...

A facile mechanochemical approach to synthesize Zn-Al layered double hydroxide

Energy Technology Data Exchange (ETDEWEB)

Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Huang, Pengwu [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 (China)

2017-06-15

In this study, a mechanochemical route to synthesize Zn-Al layered double hydroxide (LDH) was introduced, in which Zn basic carbonate and Al hydroxide were first dry milled into an activated state and then agitated in water to obtain the final products. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG) and Scanning electron microscopy (SEM). The products possessed a high crystallinity of Zn–Al LDH phase without any other impurities, proving a facile and effective preparation of Zn–Al LDH by using non-heating mechanochemical approach. - Highlights: • A non-heating mechanochemical route to synthesize Zn-Al LDH. • The products possessed high crystalline Zn-Al LDH phase. • No emission of other impurities or wastewater.

The preparation of layered double hydroxide wrapped carbon nanotubes and their application as a flame retardant for polypropylene

International Nuclear Information System (INIS)

Du Baoxian; Fang Zhengping

2010-01-01

Carbon nanotubes (CNTs) wrapped with layered double hydroxide (LDH-w-CNTs) were facilely obtained through in situ introduction of CNTs into the hydrothermal reaction system of LDH, with the goal of combining their unique physical and chemical characteristics to meet new advanced applications. Morphological observations indicated that LDH lamellae enwrapped the surface of CNTs and the wrapping degree was dependent on the functionalization of CNTs. ζ-potential measurements showed that the interaction between the positive charge of LDH and the negative charge of CNTs was the main driving force of the wrapping process. Both hybrids led to a reduction in the peak heat release rate (PHRR) of polypropylene, indicating that they could confer better flame retardancy on polypropylene with respect to LDH and CNTs.

Enhanced electrochemical performance of CoAl-layered double hydroxide nanosheet arrays coated by platinum films

International Nuclear Information System (INIS)

Cheng, J.P.; Fang, J.H.; Li, M.; Zhang, W.F.; Liu, F.; Zhang, X.B.

2013-01-01

Graphical abstract: Schematic illustration for the electron transport between the current collector and the active CoAl LDH arrays, where the yellow arrows indicate the high resistance of CoAl LDH, while the green arrows present the high conductivity of Pt films on LDH. -- Highlights: •CoAl layered double hydroxide nanosheet arrays are synthesized by hydrothermal method. •Pt films coated on surface of CoAl nanosheets facilitate fast electron transport. •CoAl LDH nanosheets coated with Pt film for 5 min have an excellent performance. -- Abstract: Three-dimensional network of cobalt and aluminum layered double hydroxide (LDH) nanosheets was synthesized on nickel foam by a simple hydrothermal method. The CoAl-LDH nonosheets were subsequently coated by ion sputtering with thin layers of Pt films to facilitate fast electron transport between current collector and the CoAl-LDH active materials. The optimal thickness of the Pt film acquiring the best performance was identified by applying various sputtering time in controlled experiments. The supercapacitor built by the CoAl-LDH nanosheets coated with Pt film sputtered for 5 min has a high specific capacitance (734.4 F g −1 at 3 A g −1 ), excellent rate capability as well as cycling stability. Moreover, it showed a long life of 77% retention after 6000 cycles and its general morphology was preserved after the test. The synergetic affect of conductive layer of Pt films and CoAl-LDH on the improvement of electrochemical properties was discussed and this would provide a useful clue in designing novel and effective electrode materials for supercapacitors

Protein (Cyanobacteria): 493036452 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available oration protein HypA Coleofasciculus chthonoplastes MHETDMTKALILTVRQWWEEQPSRPQIDTIH... WP_006104069.1 ... 1117:21745 ... 1150:63074 1301283:85471 ... 669368:4227 64178:4227 ... hydrogenase nickel incorp

Plasma Lactate Dehydrogenase Levels Predict Mortality in Acute Aortic Syndromes

Science.gov (United States)

Morello, Fulvio; Ravetti, Anna; Nazerian, Peiman; Liedl, Giovanni; Veglio, Maria Grazia; Battista, Stefania; Vanni, Simone; Pivetta, Emanuele; Montrucchio, Giuseppe; Mengozzi, Giulio; Rinaldi, Mauro; Moiraghi, Corrado; Lupia, Enrico

2016-01-01

Abstract In acute aortic syndromes (AAS), organ malperfusion represents a key event impacting both on diagnosis and outcome. Increased levels of plasma lactate dehydrogenase (LDH), a biomarker of malperfusion, have been reported in AAS, but the performance of LDH for the diagnosis of AAS and the relation of LDH with outcome in AAS have not been evaluated so far. This was a bi-centric prospective diagnostic accuracy study and a cohort outcome study. From 2008 to 2014, patients from 2 Emergency Departments suspected of having AAS underwent LDH assay at presentation. A final diagnosis was obtained by aortic imaging. Patients diagnosed with AAS were followed-up for in-hospital mortality. One thousand five hundred seventy-eight consecutive patients were clinically eligible, and 999 patients were included in the study. The final diagnosis was AAS in 201 (20.1%) patients. Median LDH was 424 U/L (interquartile range [IQR] 367–557) in patients with AAS and 383 U/L (IQR 331–460) in patients with alternative diagnoses (P < 0.001). Using a cutoff of 450 U/L, the sensitivity of LDH for AAS was 44% (95% confidence interval [CI] 37–51) and the specificity was 73% (95% CI 69–76). Overall in-hospital mortality for AAS was 23.8%. Mortality was 32.6% in patients with LDH ≥ 450 U/L and 16.8% in patients with LDH < 450 U/L (P = 0.006). Following stratification according to LDH quartiles, in-hospital mortality was 12% in the first (lowest) quartile, 18.4% in the second quartile, 23.5% in the third quartile, and 38% in the fourth (highest) quartile (P = 0.01). LDH ≥ 450 U/L was further identified as an independent predictor of death in AAS both in univariate and in stepwise logistic regression analyses (odds ratio 2.28, 95% CI 1.11–4.66; P = 0.025), in addition to well-established risk markers such as advanced age and hypotension. Subgroup analysis showed excess mortality in association with LDH ≥ 450 U/L in elderly, hemodynamically stable

Plasma Lactate Dehydrogenase Levels Predict Mortality in Acute Aortic Syndromes: A Diagnostic Accuracy and Observational Outcome Study.

Science.gov (United States)

Morello, Fulvio; Ravetti, Anna; Nazerian, Peiman; Liedl, Giovanni; Veglio, Maria Grazia; Battista, Stefania; Vanni, Simone; Pivetta, Emanuele; Montrucchio, Giuseppe; Mengozzi, Giulio; Rinaldi, Mauro; Moiraghi, Corrado; Lupia, Enrico

2016-02-01

In acute aortic syndromes (AAS), organ malperfusion represents a key event impacting both on diagnosis and outcome. Increased levels of plasma lactate dehydrogenase (LDH), a biomarker of malperfusion, have been reported in AAS, but the performance of LDH for the diagnosis of AAS and the relation of LDH with outcome in AAS have not been evaluated so far.This was a bi-centric prospective diagnostic accuracy study and a cohort outcome study. From 2008 to 2014, patients from 2 Emergency Departments suspected of having AAS underwent LDH assay at presentation. A final diagnosis was obtained by aortic imaging. Patients diagnosed with AAS were followed-up for in-hospital mortality.One thousand five hundred seventy-eight consecutive patients were clinically eligible, and 999 patients were included in the study. The final diagnosis was AAS in 201 (20.1%) patients. Median LDH was 424 U/L (interquartile range [IQR] 367-557) in patients with AAS and 383 U/L (IQR 331-460) in patients with alternative diagnoses (P < 0.001). Using a cutoff of 450 U/L, the sensitivity of LDH for AAS was 44% (95% confidence interval [CI] 37-51) and the specificity was 73% (95% CI 69-76). Overall in-hospital mortality for AAS was 23.8%. Mortality was 32.6% in patients with LDH ≥ 450 U/L and 16.8% in patients with LDH < 450 U/L (P = 0.006). Following stratification according to LDH quartiles, in-hospital mortality was 12% in the first (lowest) quartile, 18.4% in the second quartile, 23.5% in the third quartile, and 38% in the fourth (highest) quartile (P = 0.01). LDH ≥ 450 U/L was further identified as an independent predictor of death in AAS both in univariate and in stepwise logistic regression analyses (odds ratio 2.28, 95% CI 1.11-4.66; P = 0.025), in addition to well-established risk markers such as advanced age and hypotension. Subgroup analysis showed excess mortality in association with LDH ≥ 450 U/L in elderly, hemodynamically stable and in nonsurgically

Synthesis of functionalized MgAl-layered double hydroxides via modified mussel inspired chemistry and their application in organic dye adsorption.

Science.gov (United States)

Zhao, Jiao; Huang, Qiang; Liu, Meiying; Dai, Yanfeng; Chen, Junyu; Huang, Hongye; Wen, Yuanqing; Zhu, Xiaoli; Zhang, Xiaoyong; Wei, Yen

2017-11-01

In this paper, a novel strategy for the preparation of poly(levodopa) functionalized MgAl-layered double hydroxide (PDOPA-f-LDH) was developed based on the modified mussel inspired chemistry. The utilization of PDOPA-f-LDH for the removal of methylene blue (MB) from aqueous solution was also examined. Taken advantage of the self-polymerization of levodopa (DOPA) in alkaline solution and the strong affinity of catechol groups to the substrate surface, the LDH was covered homogeneously by a layer of polymer coating of DOPA, leading to the functionalization toward LDH. The structure, surface morphology, thermostability and elemental composition of as-prepared PDOPA-f-LDH were investigated by the transmission electron microscope, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Besides, the surface charge of the PDOPA-f-LDH was also investigated using zeta potential. The effects of various parameters, including contact time, initial MB concentration, solution pH and temperature, on the adsorption of MB onto PDOPA-f-LDH were systematically investigated. Results show that the adsorption capacity of functionalized LDH at 25°C could reach up to 102mg/g, which is much higher than that of pure LDH in the same experimental conditions. The adsorption kinetics and isotherm of MB adsorption were studied in batch experiments. The pseudo-second-order model is found to be the best to describe the adsorption kinetics. The isotherm result shows that the Freundlich isotherm is the better-fit-isotherm model to represent the equilibrium data. The values of thermodynamic parameters, including enthalpy change ΔH 0 , entropy change ΔS 0 and Gibbs free energy change ΔG 0 , were also determined. All the ΔG 0 values are negative; the ΔH 0 and ΔS 0 values of PDOPA-f-LDH were -7.824kJmol -1 and -0.01562kJmol -1 K -1 , respectively. And the activation energy of system (E a ) is calculated as 24.69k

Silicification-induced cell aggregation for the sustainable production of H2 under aerobic conditions.

Science.gov (United States)

Xiong, Wei; Zhao, Xiaohong; Zhu, Genxing; Shao, Changyu; Li, Yaling; Ma, Weimin; Xu, Xurong; Tang, Ruikang

2015-10-05

Photobiological hydrogen production is of great importance because of its promise for generating clean renewable energy. In nature, green algae cannot produce hydrogen as a result of the extreme sensitivity of hydrogenase to oxygen. However, we find that silicification-induced green algae aggregates can achieve sustainable photobiological hydrogen production even under natural aerobic conditions. The core-shell structure of the green algae aggregates creates a balance between photosynthetic electron generation and hydrogenase activity, thus allowing the production of hydrogen. This finding provides a viable pathway for the solar-driven splitting of water into hydrogen and oxygen to develop green energy alternatives by using rationally designed cell-material complexes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and inhibition properties of molybdate intercalated ZnAlCe layered double hydroxide

Energy Technology Data Exchange (ETDEWEB)

Yan, Huajie; Wang, Jihui, E-mail: jhwang@tju.edu.cn; Zhang, Yu; Hu, Wenbin

2016-09-05

ZnAlCe layered double hydroxide intercalated by molybdate (ZnAlCe−MoO{sub 4} LDH) was successfully synthesized by using co-precipitation method, and the morphology, structure of ZnAlCe−MoO{sub 4} LDH were observed and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. The inhibition behavior of ZnAlCe−MoO{sub 4} LDH for Q235 steel in 3.5%NaCl solution was determined by polarization curves, electrochemical impedance spectroscopy (EIS), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray photoelectron spectrometer (XPS) methods. The results shows that the synthesized ZnAlCe−MoO{sub 4} LDH has a lamellar structure with a particle size of 0.1–2.0 μm, an average thickness of 30 nm, and a basal plane spacing of 0.898 nm. Compared with the addition of ZnAl layered double hydroxide intercalated by nitrate (ZnAl−NO{sub 3} LDH) and ZnAl layered double hydroxide intercalated by molybdate (ZnAl−MoO{sub 4} LDH) in 3.5% NaCl solution, Q235 steel in 3.5%NaCl + ZnAlCe−MoO{sub 4} LDH solution has a lower corrosion current density, larger polarization resistance and a higher inhibition efficiency. The addition of ZnAlCe−MoO{sub 4} LDH will reduce the chloride concentration in 3.5% NaCl solution by the anion exchanged with molybdate, and improve the corrosion resistance of Q235 steel owing to the formation of passive film with the composition of ferrous or iron molybdate and deposition film with zinc and cerium hydroxides. - Highlights: • ZnAlCe−MoO{sub 4} LDH compound was successfully synthesized by co-precipitation method. • ZnAlCe−MoO{sub 4} LDH has a better inhibition effect to Q235 steel in 3.5%NaCl solution. • The Cl{sup −} ions in solution was partially exchanged with MoO{sub 4}{sup 2−} ions in host layers. • The passive film and deposition film were formed by the release of LDH compound.

In vivo pharmacological evaluation and efficacy study of methotrexate-encapsulated polymer-coated layered double hydroxide nanoparticles for possible application in the treatment of osteosarcoma.

Science.gov (United States)

Ray, Sayantan; Saha, Suman; Sa, Biswanath; Chakraborty, Jui

2017-04-01

Considering the existing drawbacks of methotrexate (MTX) with respect to its solubility and toxicity, we incorporated it in a nanoceramic matrix, Mg-Al-layered double hydroxide (LDH) to form LDH-MTX nanoparticles, and the same was in turn encapsulated in a nontoxic and biodegradable polymer, poly (D,L-lactide-co-glycolide) (PLGA), to arrest the initial burst release and dose-dumping-related toxicity, already reported by our group. Our present study was designed to evaluate the pharmacokinetics, tissue distribution, survival rate of the test animals, and antitumor efficacy of the PLGA-LDH-MTX nanoparticles and its counterpart without LDH, PLGA-MTX nanoparticles compared with bare MTX. The median lethal dose (LD 50 ) of the former was higher, compared with bare MTX, using Balb/c nude mice, indicating it to be completely safe for use. Also, a comparative pharmacokinetic and antitumour efficacy study using MTX, PLGA-MTX, and PLGA-LDH-MTX nanoparticles in osteosarcoma-induced Balb/c nude mice in vivo demonstrated superiority of PLGA-LDH-MTX as compared to PLGA-MTX and bare MTX. The results suggest that PLGA-LDH-MTX nanoparticles might exhibit potential advantages over the present-day chemotherapy over bare MTX, for the possibility of treatment of osteosarcoma.

Use of calcined layered double hydroxides for the removal of color and organic matter from textile effluents: kinetic, equilibrium and recycling studies

Directory of Open Access Journals (Sweden)

T. P. F. Teixeira

2014-03-01

Full Text Available This paper presents data for the synthesis and characterization of layer double hydroxides (LDH and their use for color and chemical oxygen demand (COD removal from effluents generated by a textile industry. Adsorption studies with raw and biologically treated (activated sludge textile effluent showed that the pseudo-second order model best fitted the experimental data, leading to adsorption coefficients of 39.1 and 102.9 mgCOD/gLDH for raw and treated effluents, respectively. The best conditions for color and COD removal were obtained at lower values of temperature and pH (25 °C and pH 7 and, in these conditions, an LDH dose of 10 g/L resulted in color removal efficiencies of 56% for samples of raw and 66% for samples of treated effluent. Recycling studies indicated that the reuse of thermally treated LDH led to a progressive loss in the removal efficiencies of COD and color. The reduction was more pronounced with samples of the raw textile effluent. LDH characterization performed before and after each adsorption and regeneration experiment showed that there was no intercalation of dye molecules in the interlayer region of the LDH, indicating that COD and color removal might be due to the adsorption of organic molecules onto the LDH surface.

Polyhedral-Like NiMn-Layered Double Hydroxide/Porous Carbon as Electrode for Enhanced Electrochemical Performance Supercapacitors.

Science.gov (United States)

Yu, Mei; Liu, Ruili; Liu, Jianhua; Li, Songmei; Ma, Yuxiao

2017-11-01

Polyhedral-like NiMn-layered double hydroxide/porous carbon (NiMn-LDH/PC-x) composites are successfully synthesized by hydrothermal method (x = 1, 2 means different mass percent of porous carbon (PC) in composites). The NiMn-LDH/PC-1 composites possess specific capacitance 1634 F g -1 at a current density of 1 A g -1 , and it is much better than that of pure LDH (1095 F g -1 at 1 A g -1 ). Besides, the sample can retain 84.58% of original capacitance after 3000 cycles at 15 A g -1 . An asymmetric supercapacitor with NiMn-LDH/PC-1 as anode and activated carbon as cathode is fabricated, and the supercapacitor can achieve an energy density of 18.60 Wh kg -1 at a power density of 225.03 W kg -1 . The enhanced electrochemical performance attributes to the high faradaic pseudocapacitance of NiMn-LDH, the introduction of PC, and the 3D porous structure of LDH/PC-1 composites. The introduction of PC hinders serious agglomeration of LDH and further accelerates ions transport. The encouraging results indicate that these materials are one of the most potential candidates for energy storage devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lactate Dehydrogenase Is an Important Prognostic Indicator for Hepatocellular Carcinoma after Partial Hepatectomy

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Jing-Ping Zhang

2015-12-01

Full Text Available Preoperative serum lactate dehydrogenase (LDH has been used as a prognostic indicator for patients with hepatocellular carcinoma (HCC treated with sorafenib or undergoing transcatheter arterial chemoembolization, but its significance in predicting survival of HCC patients who received curative resection remains undefined. A total of 683 patients with histopathologically confirmed HCC were enrolled in this study. The prognostic significance of preoperative serum LDH was determined by Kaplan-Meier analysis and a Cox proportional hazards regression model. The association between the preoperative serum LDH and clinicopathological parameters was evaluated by the χ2 test or linear regression analysis when appropriate. Higher preoperative serum LDH level was associated with worse prognosis. In a multivariate Cox proportional hazards analysis, the preoperative serum LDH level could predict overall survival and recurrence independently. Higher preoperative serum LDH level is associated with the elevated serum alpha-fetoprotein, the presence of hepatitis B surface antigen, larger tumor size, the presence of macrovascular invasion, the advanced tumor–lymph node–metastasis stage, worse tumor differentiation, and Child-Pugh B. Preoperative serum LDH level was an inexpensive, simple, convenient, and routinely measured biomarker exhibiting a potential to select patients at high risk with poor clinical outcome for appropriate treatment strategies.

Positive selection on D-lactate dehydrogenases of Lactobacillus delbrueckii subspecies bulgaricus.

Science.gov (United States)

Zhang, Jifeng; Gong, Guangyu; Wang, Xiao; Zhang, Hao; Tian, Weidong

2015-08-01

Lactobacillus delbrueckii has been widely used for yogurt fermentation. It has genes encoding both D- and L-type lactate dehydrogenases (LDHs) that catalyse the production of L(+) or D(-) stereoisomer of lactic acid. D-lactic acid is the primary lactate product by L. delbrueckii, yet it cannot be metabolised by human intestine. Since it has been domesticated for long time, an interesting question arises regarding to whether the selection pressure has affected the evolution of both L-LDH and D-LDH genes in the genome. To answer this question, in this study the authors first investigated the evolution of these two genes by constructing phylogenetic trees. They found that D-LDH-based phylogenetic tree could better represent the phylogenetic relationship in the acidophilus complex than L-LDH-based tree. They next investigated the evolutions of LDH genes of L. delbrueckii at amino acid level, and found that D-LDH gene in L. delbrueckii is positively selected, possibly a consequence of long-term domestication. They further identified four amino acids that are under positive selection. One of them, V261, is located at the centre of three catalytic active sites, indicating likely functional effects on the enzyme activity. The selection from the domestication process thus provides direction for future engineering of D-LDH.

Biochemical factors affecting the quantum efficiency of hydrogen production by membranes of green photosynthetic bacteria

Energy Technology Data Exchange (ETDEWEB)

Bernstein, J.D.; Olson, J.M.

1981-01-01

Photohydrogen production, 200-700 ..mu..mol H/sub 2/ h/sup -1/ (mg bacteriochlorophyll a)/sup -1/ has been obtained in a system containing unit membrane vesicles (Complex I) from the green photosynthetic bacterium Chlorobium limicola f. thiosulfatophilum, ascorbate, N,N,N',N'-tetramethyl-p-phenylenediamine, dithioerythritol, an oxygen scavenging mixture, either methyl viologen (MV) or clostridial ferredoxin (CPS Fd) as electron carrier, and either CPS hydrogenase or platinum asbestos as catalyst. All components are necessary for maximum activity, and spinach Fd cannot be substituted for CPS Fd. Higher rates of photohydrogen production are obtained using MV or CPS Fd with hydrogenase than with MV and Pt asbestos. The highest quantum efficiencies (7-10% at 0.2-0.9 mW absorbed light and over 20% at lower light) were obtained with CPS Fd, hydrogenase and non-saturating 812 nm light. With saturating white light, however, rates of photohydrogen production varied relatively little among the various combinations of electron carrier and catalyst tested. The reaction rate is unaffected by 0.03% Triton X-100, and is insensitive to treatment with antimycin a or m-chloro-carbonyl cyanide phenylhydrazone.This indicates that neither electron flow through an endogenous cyclic chain, nor maintenance of a proton gradient are involved in this process.

Effect of light on respiration and development of photosynthetic cells. Progress report, September 1, 1975--June 1, 1976

Energy Technology Data Exchange (ETDEWEB)

Gibbs, M

1976-06-01

Adaptation and deadaptation of unicellular algal cells to a hydrogen metabolism may involve not only hydrogenase but also the site of entry of electrons from NADH. NADPH can also serve as an electron donor in a chloroplast preparation fortified with hydrogenase but the rate of photoevolution falls off rapidly perhaps due to competition with NADP for electrons. The evolution of H/sub 2/ with reduced pyridine nucleotide as electron donor is coupled to ATP formation. Evidence is presented that soluble ferredoxin may not be the immediate donor of H/sub 2/. Hydrogenases from Chlamydomonas and Scenedesmus have been highly purified and will be used to test the stoichiometry of NADH disappearance, ATP and H/sub 2/ formation and also whether H/sub 2/-photoevolution in contrast to dark evolution is ferredoxin dependent. Studies with intact Chlamydomonas provide evidence that a reduced carbon compound and not water is the source of H/sub 2/. The presence of acetate eliminates the CO/sub 2/ production. The ratio of CO/sub 2/:H/sub 2/ is 1:2 and evolution is blocked by inhibitors of glycolysis. Acetate has a strong effect on H/sub 2/O. Cells starved over a long period still retain photoreduction but will not evolve H/sub 2/ until glucose is added.

Tailoring surface properties and structure of layered double hydroxides using silanes with different number of functional groups

Energy Technology Data Exchange (ETDEWEB)

Tao, Qi [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); He, Hongping, E-mail: hehp@gig.ac.cn [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Li, Tian [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese, Academy of Sciences, Beijing 100039 (China); Frost, Ray L. [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Zhang, Dan; He, Zisen [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese, Academy of Sciences, Beijing 100039 (China)

2014-05-01

Four silanes, trimethylchlorosilane (TMCS), dimethyldiethoxylsilane (DMDES), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS), were adopted to graft layered double hydroxides (LDH) via an induced hydrolysis silylation method (IHS). Fourier transform infrared spectra (FTIR) and {sup 29}Si MAS nuclear magnetic resonance spectra ({sup 29}Si MAS NMR) indicated that APTES and TEOS can be grafted onto LDH surfaces via condensation with hydroxyl groups of LDH, while TMCS and DMDES could only be adsorbed on the LDH surface with a small quantity. A combination of X-ray diffraction patterns (XRD) and {sup 29}Si MAS NMR spectra showed that silanes were exclusively present in the external surface and had little influence on the long range order of LDH. The surfactant intercalation experiment indicated that the adsorbed and/or grafted silane could not fix the interlamellar spacing of the LDH. However, they will form crosslink between the particles and affect the further surfactant intercalation in the silylated samples. The replacement of water by ethanol in the tactoids and/or aggregations and the polysiloxane oligomers formed during silylation procedure can dramatically increase the value of BET surface area (S{sub BET}) and total pore volumes (V{sub p}) of the products. - Graphical abstract: The replacement of water by ethanol in the tactoids and aggregations of LDHs, and the polysiloxane oligomers formed during silylation process can dramatically increase the BET surface area (S{sub BET}) and the total pore volume (V{sub p}) of the silylated products. - Highlights: • Silanes with multifunctional groups were grafted onto LDH surface in C{sub 2}H{sub 5}OH medium. • The number of hydrolysable groups in silanes affects the structure of grafted LDH. • Replacement of H{sub 2}O by C{sub 2}H{sub 5}OH in aggregations increases S{sub BET} and V{sub p} of grafted LDH. • Polysiloxane oligomers contribute to the increase of S{sub BET} and V{sub p} of grafted LDH.

Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

Energy Technology Data Exchange (ETDEWEB)

Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu [School of Resources and Environment Engineering, Wuhan University of Technology, Wuhan 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 (China)

2017-01-15

Al(OH){sub 3} and Ca(OH){sub 2} powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. - Graphical abstract: Activated Ca-Al hydroxides (C{sub 3}A) transformed into Ca-Al-OH compound when agitated in water. Ca-Al precursor (C{sub 3}A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO{sub 4} LDH product. Ca-Al-CrO{sub 4} LDH phase occurred preferentially to Ca-Al-MCl{sub 2} LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. - Highlights: • Activated Ca-Al hydroxides transformed into LDH when agitated in water with some inorganic substances. • Hexavalent Cr was incorporated in the LDH structure at high adsorption capacity. • Ca-Al-Cr LDH phase occurred preferentially to Ca-Al-MCl{sub 2} LDH phases with coexistence. • The prepared Ca-Al hydroxides had high performance as adsorbent even with high salinity of the solution.

Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

International Nuclear Information System (INIS)

Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

2017-01-01

Al(OH) 3 and Ca(OH) 2 powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. - Graphical abstract: Activated Ca-Al hydroxides (C 3 A) transformed into Ca-Al-OH compound when agitated in water. Ca-Al precursor (C 3 A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO 4 LDH product. Ca-Al-CrO 4 LDH phase occurred preferentially to Ca-Al-MCl 2 LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. - Highlights: • Activated Ca-Al hydroxides transformed into LDH when agitated in water with some inorganic substances. • Hexavalent Cr was incorporated in the LDH structure at high adsorption capacity. • Ca-Al-Cr LDH phase occurred preferentially to Ca-Al-MCl 2 LDH phases with coexistence. • The prepared Ca-Al hydroxides had high performance as adsorbent even with high salinity of the solution.

Controllable preparation of multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide nanorods/nanosheets on electrospun carbon nanofibers for high-performance supercapacitors

International Nuclear Information System (INIS)

Lai, Feili; Huang, Yunpeng; Miao, Yue-E; Liu, Tianxi

2015-01-01

Graphical Abstract: Multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide nanorods/nanosheets grown on electrospun carbon nanofiber membranes were prepared via electrospinning combined with solution co-deposition for high-performance supercapacitor electrodes. - Highlights: • Ni-Co LDH@CNFhybridswerepreparedbyelectrospinningandsolutionco-deposition. • Ni-Co LDH@CNF hybrids show high electrochemical performance for supercapacitors. • This method can be extended to other bimetallic@CNF hybrids for electrode materials. - Abstract: Hybrid nanomaterials with hierarchical structures have been considered as one kind of the most promising electrode materials for high-performance supercapacitors with high capacity and long cycle lifetime. In this work, multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanorods/nanosheets on carbon nanofibers (CNFs) were prepared by electrospinning technique combined with one-step solution co-deposition method. Carbon nanofiber membranes were obtained by electrospinning of polyacrylonitrile (PAN) followed by pre-oxidation and carbonization. The successful growth of Ni-Co LDH with different morphologies on CNF membrane by using two kinds of auxiliary agents reveals the simplicity and universality of this method. The uniform and immense growth of Ni-Co LDH on CNFs significantly improves its dispersion and distribution. Meanwhile the hierarchical structure of carbon nanofiber@nickel-cobalt layered double hydroxide nanorods/nanosheets (CNF@Ni-Co LDH NR/NS) hybrid membranes provide not only more active sites for electrochemical reaction but also more efficient pathways for electron transport. Galvanostatic charge-discharge measurements reveal high specific capacitances of 1378.2 F g −1 and 1195.4 F g −1 (based on Ni-Co LDH mass) at 1 A g −1 for CNF@Ni-Co LDH NR and CNF@Ni-Co LDH NS hybrid membranes, respectively. Moreover, cycling stabilities for both hybrid membranes are

Characterization of the galactono-1,4-lactone dehydrogenase from pepper fruits and its modulation in the ascorbate biosynthesis. Role of nitric oxide.

Science.gov (United States)

Rodríguez-Ruiz, Marta; Mateos, Rosa M; Codesido, Verónica; Corpas, Francisco J; Palma, José M

2017-08-01

Pepper fruit is one of the highest vitamin C sources of plant origin for our diet. In plants, ascorbic acid is mainly synthesized through the L-galactose pathway, being the L-galactono-1,4-lactone dehydrogenase (GalLDH) the last step. Using pepper fruits, the full GalLDH gene was cloned and the protein molecular characterization accomplished. GalLDH protein sequence (586 residues) showed a 37 amino acids signal peptide at the N-terminus, characteristic of mitochondria. The hydrophobic analysis of the mature protein displayed one transmembrane helix comprising 20 amino acids at the N-terminus. By using a polyclonal antibody raised against a GalLDH internal sequence and immunoblotting analysis, a 56kDa polypeptide cross-reacted with pepper fruit samples. Using leaves, flowers, stems and fruits, the expression of GalLDH by qRT-PCR and the enzyme activity were analyzed, and results indicate that GalLDH is a key player in the physiology of pepper plants, being possibly involved in the processes which undertake the transport of ascorbate among different organs. We also report that an NO (nitric oxide)-enriched atmosphere enhanced ascorbate content in pepper fruits about 40% parallel to increased GalLDH gene expression and enzyme activity. This is the first report on the stimulating effect of NO treatment on the vitamin C concentration in plants. Accordingly, the modulation by NO of GalLDH was addressed. In vitro enzymatic assays of GalLDH were performed in the presence of SIN-1 (peroxynitrite donor) and S-nitrosoglutahione (NO donor). Combined results of in vivo NO treatment and in vitro assays showed that NO provoked the regulation of GalLDH at transcriptional and post-transcriptional levels, but not post-translational modifications through nitration or S-nitrosylation events promoted by reactive nitrogen species (RNS) took place. These results suggest that this modulation point of the ascorbate biosynthesis could be potentially used for biotechnological purposes to

Lactate dehydrogenase is not a mitochondrial enzyme in human and mouse vastus lateralis muscle

DEFF Research Database (Denmark)

Rasmussen, Hans N; van Hall, Gerrit; Rasmussen, Ulla F

2002-01-01

The presence of lactate dehydrogenase in skeletal muscle mitochondria was investigated to clarify whether lactate is a possible substrate for mitochondrial respiration. Mitochondria were prepared from 100 mg samples of human and mouse vastus lateralis muscle. All fractions from the preparation...... procedure were assayed for marker enzymes and lactate dehydrogenase (LDH). The mitochondrial fraction contained no LDH activity (detection limit approximately 0.05 % of the tissue activity) and the distribution of LDH activity among the fractions paralleled that of pyruvate kinase, i.e. LDH was fractionated...... as a cytoplasmic enzyme. Respiratory experiments with the mitochondrial fraction also indicated the absence of LDH. Lactate did not cause respiration, nor did it affect the respiration of pyruvate + malate. The major part of the native cytochrome c was retained in the isolated mitochondria, which, furthermore...

Antimalarial activity of potential inhibitors of Plasmodium falciparum lactate dehydrogenase enzyme selected by docking studies.

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Julia Penna-Coutinho

Full Text Available The Plasmodium falciparum lactate dehydrogenase enzyme (PfLDH has been considered as a potential molecular target for antimalarials due to this parasite's dependence on glycolysis for energy production. Because the LDH enzymes found in P. vivax, P. malariae and P. ovale (pLDH all exhibit ∼90% identity to PfLDH, it would be desirable to have new anti-pLDH drugs, particularly ones that are effective against P. falciparum, the most virulent species of human malaria. Our present work used docking studies to select potential inhibitors of pLDH, which were then tested for antimalarial activity against P. falciparum in vitro and P. berghei malaria in mice. A virtual screening in DrugBank for analogs of NADH (an essential cofactor to pLDH and computational studies were undertaken, and the potential binding of the selected compounds to the PfLDH active site was analyzed using Molegro Virtual Docker software. Fifty compounds were selected based on their similarity to NADH. The compounds with the best binding energies (itraconazole, atorvastatin and posaconazole were tested against P. falciparum chloroquine-resistant blood parasites. All three compounds proved to be active in two immunoenzymatic assays performed in parallel using monoclonals specific to PfLDH or a histidine rich protein (HRP2. The IC(50 values for each drug in both tests were similar, were lowest for posaconazole (<5 µM and were 40- and 100-fold less active than chloroquine. The compounds reduced P. berghei parasitemia in treated mice, in comparison to untreated controls; itraconazole was the least active compound. The results of these activity trials confirmed that molecular docking studies are an important strategy for discovering new antimalarial drugs. This approach is more practical and less expensive than discovering novel compounds that require studies on human toxicology, since these compounds are already commercially available and thus approved for human use.

Evolutionary factors affecting Lactate dehydrogenase A and B variation in the Daphnia pulex species complex

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Cristescu Melania E

2011-07-01

Full Text Available Abstract Background Evidence for historical, demographic and selective factors affecting enzyme evolution can be obtained by examining nucleotide sequence variation in candidate genes such as Lactate dehydrogenase (Ldh. Two closely related Daphnia species can be distinguished by their electrophoretic Ldh genotype and habitat. Daphnia pulex populations are fixed for the S allele and inhabit temporary ponds, while D. pulicaria populations are fixed for the F allele and inhabit large stratified lakes. One locus is detected in most allozyme surveys, but genome sequencing has revealed two genes, LdhA and LdhB. Results We sequenced both Ldh genes from 70 isolates of these two species from North America to determine if the association between Ldh genotype and habitat shows evidence for selection, and to elucidate the evolutionary history of the two genes. We found that alleles in the pond-dwelling D. pulex and in the lake-dwelling D. pulicaria form distinct groups at both loci, and the substitution of Glutamine (S for Glutamic acid (F at amino acid 229 likely causes the electrophoretic mobility shift in the LDHA protein. Nucleotide diversity in both Ldh genes is much lower in D. pulicaria than in D. pulex. Moreover, the lack of spatial structuring of the variation in both genes over a wide geographic area is consistent with a recent demographic expansion of lake populations. Neutrality tests indicate that both genes are under purifying selection, but the intensity is much stronger on LdhA. Conclusions Although lake-dwelling D. pulicaria hybridizes with the other lineages in the pulex species complex, it remains distinct ecologically and genetically. This ecological divergence, coupled with the intensity of purifying selection on LdhA and the strong association between its genotype and habitat, suggests that experimental studies would be useful to determine if variation in molecular function provides evidence that LDHA variants are adaptive.

Enzymatic and thermodynamic profiles of a heterotetramer lactate dehydrogenase isozyme in swine

International Nuclear Information System (INIS)

Goto, Tatsufumi; Sugawara, Kotomi; Nakamura, Shigeyoshi; Kidokoro, Shun-Ichi; Wakui, Hideki; Nunomura, Wataru

2016-01-01

Lactate dehydrogenase (LDH) is a glycolytic enzyme that catalyzes the final step of glycolysis and produces NAD + . In somatic cells, LDH forms homotetramers and heterotetramers that are encoded by two different genes: LDHA (skeletal muscle type, M) and LDHB (heart type, H). Analysis of LDH isozymes is important for understanding the physiological role of homotetramers and heterotetramers and for optimizing inhibition of their enzymatic activity as it may result in distinct effects. Previously, we reported that hydroxychloroquine (HCQ) inhibited LDH activity, but we did not examine isozyme specificity. In the present study, we isolated heterotetrameric LDH (H 2 M 2 ) from swine brain, determined its kinetic and thermodynamic properties, and examined the effect of HCQ on its activity compared to homotetrameric LDH isozymes. We show that: (1) the K m values for H 2 M 2 –mediated catalysis of pyruvate or lactate were intermediate compared to those for the homotetrameric isozymes, M 4 and H 4 whereas the V max values were similar; (2) the K m and V max values for H 2 M 2 –mediated catalysis of NADH were not significantly different among LDH isozymes; (3) the values for activation energy and van't Hoff enthalpy changes for pyruvate reduction of H 2 M 2 were intermediate compared to those for the homotetrameric isozymes; (4) the temperature for half residual activity of H 2 M 2 was closer to that for M 4 than for H 4 . We also show that HCQ had different affinities for various LDH isozymes. - Highlights: • Heterotetrameric (H 2 M 2 ) LDH isozyme was isolated from swine brain. • Kinetics of H 2 M 2 were intermediate between the two homotetramers. • Thermodynamics of H 2 M 2 were also intermediate between the two homotetramers. • Hydroxychloroquine inhibited more strongly H 2 M 2 than homotetramers.

Outcomes After Lumbar Disc Herniation in the National Basketball Association.

Science.gov (United States)

Minhas, Shobhit V; Kester, Benjamin S; Hsu, Wellington K

2016-01-01

Professional basketball players are at risk for lumbar disc herniation (LDH), yet the evidence guiding treatment after operative or nonoperative management of this condition in the National Basketball Association (NBA) is limited. NBA players with LDH will have different performance outcomes based on treatment type. Case-control study. Level 4. Athletes in the NBA with an LDH were identified through team injury reports, transaction records, and public sports archives. A 1:2 case-control study was performed in which LDH players and players without LDH were matched for player variables. Statistical analysis was employed to compare pre- and postindex season performance (games played and player efficiency rating [PER]) and career longevity between test subjects and controls in the operatively treated (OT) and nonoperatively treated (NOT) cohorts. A total of 61 NBA players with LDH were included, of whom 34 underwent discectomy and 27 were managed nonoperatively. Return-to-play (RTP) rates did not differ between NOT and OT players (77.8% vs. 79.4%). When compared with controls, OT players played significantly fewer games and had a lower PER than controls during the first postoperative season, but no difference was seen 2 and 3 years after surgery, with no difference in postoperative career length. In contrast, no difference in games played or PER was seen between NOT players and controls, although NOT players played significantly fewer postindex seasons. NBA players have a high RTP rate regardless of type of treatment for LDH; however, postindex performance differs between surgically and nonoperatively managed patients when compared with players without an LDH. However, further studies with a larger sample size are required for more definitive recommendations. There is a high RTP rate after LDH in the NBA, although postindex performance may differ based on operative versus nonoperative treatment. © 2015 The Author(s).

Protein (Cyanobacteria): 504995873 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available Hydrogenase-3 nickel incorporation protein HypA Microcoleus sp. PCC 7113 MHEVGIMQNTLDIALEYANRQGAAQIHRMTLRIGQ... WP_015182975.1 ... 1117:21745 ... 1150:36937 1301283:56429 ... 44471:3321 1173027:436 ...

Protein (Cyanobacteria): 504985265 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available poration protein HypA Geitlerinema sp. PCC 7407 MTKALLMTLHDWWESQPDRPKIDKVHLVVGQFTCV... WP_015172367.1 ... 1117:21745 ... 1150:57512 1301283:79291 ... 63132:2365 1173025:1620 ... hydrogenase nickel incor

Protein (Cyanobacteria): 504993053 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available Hydrogenase-3 nickel incorporation protein HypA Microcoleus sp. PCC 7113 MHETDMTKALIVTVRDWWEAQPEHPKISHIYLTVG... WP_015180155.1 ... 1117:21745 ... 1150:36937 1301283:56429 ... 44471:3321 1173027:436 ...

Acid Green 1 removal from wastewater by layered double hydroxides

Science.gov (United States)

Elkhattabi, El Hassan; Lakraimi, Mohamed; Berraho, Moha; Legrouri, Ahmed; Hammal, Radouan; El Gaini, Layla

2018-03-01

The paper presents the removal of Acid Green 1 (AG1) from aqueous solutions by [Zn-Al-Cl]-layered double hydroxides (LDHs). The LDH was prepared by coprecipitation at constant pH. The affinity of this material for AG1 was studied as a function of contact time, pH of the solution, LDH dose and AG1/LDH mass ratio. It was found that 32 h are enough to reach the equilibrium with a maximum retention at pH 8 for an LDH dose of 100 mg and with an AG1/LDH mass ratio higher than 2. The adsorption isotherm is of L-type, as described by the Langmuir model. The results demonstrate that AG1 retention on LDHs occurs by adsorption on external surface when AG1/LDH mass ratio is equal or lower than 2 and by both adsorption and interlayer ion exchange for ratios higher than 2. A mechanism for the AG1 removal has been confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric-differential thermal analyses and scanning electron microscopy.

Solvothermal one-step synthesis of Ni-Al layered double hydroxide/carbon nanotube/reduced graphene oxide sheet ternary nanocomposite with ultrahigh capacitance for supercapacitors.

Science.gov (United States)

Yang, Wanlu; Gao, Zan; Wang, Jun; Ma, Jing; Zhang, Milin; Liu, Lianhe

2013-06-26

A Ni-Al layered double hydroxide (LDH), mutil-wall carbon nanotube (CNT), and reduced graphene oxide sheet (GNS) ternary nanocomposite electrode material has been developed by a facile one-step ethanol solvothermal method. The obtained LDH/CNT/GNS composite displayed a three-dimensional (3D) architecture with flowerlike Ni-Al LDH/CNT nanocrystallites gradually self-assembled on GNS nanosheets. GNS was used as building blocks to construct 3D nanostructure, and the LDH/CNT nanoflowers in turn separated the two-dimensional (2D) GNS sheets, which preserved the high surface area of GNSs. Furthermore, the generated porous networks with a narrow pore size distribution in the LDH/CNT/GNS composite were also demonstrated by the N2 adsorption/desorption experiment. Such morphology would be favorable to improve the mass transfer and electrochemical action of the electrode. As supercapacitor electrode material, the LDH/CNT/GNS hybrid exhibited excellent electrochemical performance, including ultrahigh specific capacitance (1562 F/g at 5 mA/cm(2)), excellent rate capability, and long-term cycling performance, which could be a promising energy storage/conversion material for supercapacitor application.

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

Science.gov (United States)

Ahmed, Nesreen S.; Menzel, Robert; Wang, Yifan; Garcia-Gallastegui, Ainara; Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N.; Mokhtar, Mohamed

2017-02-01

Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

Coenzyme protection of lactic dehydrogenase against inactivation by gamma-rays

International Nuclear Information System (INIS)

Saito, M.

1978-01-01

A comparison has been made of the radiation sensitivities of the ternary complexes, oxamate-LDH-NADH and pyruvate-LDH-NAD with those of free LDH molecules and the intermediate binary complexes LDH-NAD and LDH-NADH. The enzyme solutions were 60 Co γirradiated and the rate of pyruvate reduction then measured. At doses of more than 10 krad the coenzymes afforded considerable protection to LDH against inactivation, and the dose-effect curves deviated from the curve for the unprotected enzyme, implying very specific protection. Coenzyme protection for a 30 krad dose at various concentrations of NAD and NADH reached a saturation level at about 4.0 x 10 -4 M for both NAD and NADH; protection by pyruvate alone was slight in comparison. Pyruvate and NAD (or oxamate and NADH) together at 1.0 x 10 -3 M protected the enzyme in a cooperative way. The results suggest that the major events of protection occur on the substrate and coenzyme binding sites, and support the view that coenzyme binding protects the enzyme by altering its conformation. (U.K.)

Preparation and properties of blends composed of lignosulfonated layered double hydroxide/plasticized starch and thermoplastics.

Science.gov (United States)

Privas, Edwige; Leroux, Fabrice; Navard, Patrick

2013-07-01

Layered double hydroxide prepared with lignosulfonate (LDH/LS) can be easily dispersed down to the nanometric scale in thermoplastic starch, at concentration of 1 up to 4 wt% of LDH/LS. They can thus be used as a bio-based reinforcing agent of thermoplastic starch. Incorporation of LDH/LS in starch must be done using LDH/LS slurry instead of powder on order to avoid secondary particles aggregation, the water of the paste being used as the starch plasticizer. This reinforced starch was used for preparing a starch-polyolefine composite. LDH/LS-starch nanocomposites were mixed in a random terpolymer of ethylene, butyl acrylate (6%) and maleic anhydride (3%) at concentrations of 20 wt% and 40 wt%. With a 20% loading of (1 wt% LDH/LS in thermoplastic starch), the ternary copolymer is partially bio-based while keeping nearly its original processability and mechanical properties and improving oxygen barrier properties. The use of layered double hydroxides is also removing most odours linked to the lignin phase. Copyright © 2013 Elsevier Ltd. All rights reserved.

Topotactic Synthesis of Porous Cobalt Ferrite Platelets from a Layered Double Hydroxide Precursor and Their Application in Oxidation Catalysis.

Science.gov (United States)

Ortega, Klaus Friedel; Anke, Sven; Salamon, Soma; Özcan, Fatih; Heese, Justus; Andronescu, Corina; Landers, Joachim; Wende, Heiko; Schuhmann, Wolfgang; Muhler, Martin; Lunkenbein, Thomas; Behrens, Malte

2017-09-12

Monocrystalline, yet porous mosaic platelets of cobalt ferrite, CoFe 2 O 4 , can be synthesized from a layered double hydroxide (LDH) precursor by thermal decomposition. Using an equimolar mixture of Fe 2+ , Co 2+ , and Fe 3+ during co-precipitation, a mixture of LDH, (Fe II Co II ) 2/3 Fe III 1/3 (OH) 2 (CO 3 ) 1/6 ⋅m H 2 O, and the target spinel CoFe 2 O 4 can be obtained in the precursor. During calcination, the remaining Fe II fraction of the LDH is oxidized to Fe III leading to an overall Co 2+ :Fe 3+ ratio of 1:2 as required for spinel crystallization. This pre-adjustment of the spinel composition in the LDH precursor suggests a topotactic crystallization of cobalt ferrite and yields phase pure spinel in unusual anisotropic platelet morphology. The preferred topotactic relationship in most particles is [111] Spinel ∥[001] LDH . Due to the anion decomposition, holes are formed throughout the quasi monocrystalline platelets. This synthesis approach can be used for different ferrites and the unique microstructure leads to unusual chemical properties as shown by the application of the ex-LDH cobalt ferrite as catalyst in the selective oxidation of 2-propanol. Compared to commercial cobalt ferrite, which mainly catalyzes the oxidative dehydrogenation to acetone, the main reaction over the novel ex-LDH cobalt is dehydration to propene. Moreover, the oxygen evolution reaction (OER) activity of the ex-LDH catalyst was markedly higher compared to the commercial material. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Karnofsky Performance Status and Lactate Dehydrogenase Predict the Benefit of Palliative Whole-Brain Irradiation in Patients With Advanced Intra- and Extracranial Metastases From Malignant Melanoma

Energy Technology Data Exchange (ETDEWEB)

Partl, Richard, E-mail: richard.partl@medunigraz.at [Department of Therapeutic Radiology and Oncology, Medical University of Graz, Graz (Austria); Richtig, Erika [Department of Dermatology, Medical University of Graz, Graz (Austria); Avian, Alexander; Berghold, Andrea [Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Graz (Austria); Kapp, Karin S. [Department of Therapeutic Radiology and Oncology, Medical University of Graz, Graz (Austria)

2013-03-01

Purpose: To determine prognostic factors that allow the selection of melanoma patients with advanced intra- and extracerebral metastatic disease for palliative whole-brain radiation therapy (WBRT) or best supportive care. Methods and Materials: This was a retrospective study of 87 patients who underwent palliative WBRT between 1988 and 2009 for progressive or multiple cerebral metastases at presentation. Uni- and multivariate analysis took into account the following patient- and tumor-associated factors: gender and age, Karnofsky performance status (KPS), neurologic symptoms, serum lactate dehydrogenase (LDH) level, number of intracranial metastases, previous resection or stereotactic radiosurgery of brain metastases, number of extracranial metastasis sites, and local recurrences as well as regional lymph node metastases at the time of WBRT. Results: In univariate analysis, KPS, LDH, number of intracranial metastases, and neurologic symptoms had a significant influence on overall survival. In multivariate survival analysis, KPS and LDH remained as significant prognostic factors, with hazard ratios of 3.3 (95% confidence interval [CI] 1.6-6.5) and 2.8 (95% CI 1.6-4.9), respectively. Patients with KPS ≥70 and LDH ≤240 U/L had a median survival of 191 days; patients with KPS ≥70 and LDH >240 U/L, 96 days; patients with KPS <70 and LDH ≤240 U/L, 47 days; and patients with KPS <70 and LDH >240 U/L, only 34 days. Conclusions: Karnofsky performance status and serum LDH values indicate whether patients with advanced intra- and extracranial tumor manifestations are candidates for palliative WBRT or best supportive care.

Protein (Cyanobacteria): 648410610 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available WP_026102361.1 NZ_KB235920 1117:21745 ... 52604:1915 ... 44474:816 118161:1544 ... hydrogenase nickel incorpora...tion protein HypA Pleurocapsa sp. PCC 7319 MHETDMTKALILTMKDWYVSQPEQRKIEKVHLIVGQFTCV

Preparation of poly(ethylene terephthalate/layered double hydroxide nanocomposites by in-situ polymerization and their thermal property

Directory of Open Access Journals (Sweden)

Q. Jiao

2012-06-01

Full Text Available Terephthalate (TA intercalated layered double hydroxides (LDHs were synthesized using hydroxides as raw materials, and poly(ethylene terephthalate (PET/LDH nanocomposites with different contents of TA intercalated LDHs were prepared by in-situ polymerization. The structure, morphology and thermal property of PET/LDH nanocomposites were investigated. The TA intercalated LDHs were partially exfoliated and well dispersed in PET matrix. The PET/LDH nanocomposites exhibit enhanced thermal stability relative to pure PET, confirmed by the thermogravimetric analysis results. The results of differential scanning calorimetry suggest that LDH nanoparticles could effectively promote the nucleation and crystallization of PET.

Ionic Liquid as Surfactant Agent of Hydrotalcite: Influence on the Final Properties of Polycaprolactone Matrix

Directory of Open Access Journals (Sweden)

Luanda Chaves Lins

2018-01-01

Full Text Available This paper reports the surface treatment of layered double hydroxide (LDH by using ionic liquid (IL composed of phosphonium cation combined with 2-ethylhexanoate (EHT counter anion as surfactant agent. Then, different amounts (1, 3, 5 and 7 wt % of thermally stable organically modified LDH (up to 350 °C denoted LDH-EHT were incorporated into polycaprolactone (PCL matrix by mechanical milling. The influence of LDH-EHT loading has been investigated on the physical properties, such as the thermal and barrier properties, as well as the morphologies of the resulting nanocomposites. Thus, intercalated or microcomposite morphologies were obtained depending on the LDH-EHT loading, leading to significant reduction of the diffusion coefficient respect to water vapor. The modulation of barrier properties, using low functionalized filler amount, is a very important aspect for materials in packaging applications.

Changes of the lactate dehydrogenase in the tissue fraction with Walker carcinoma under irradiation

International Nuclear Information System (INIS)

Schultheis, W.

1972-01-01

The behaviour of LDH, GOT and GPT of one and the same tissue with and without irradiation treatment as a means of cancer diagnosis is presented. Parallel to this, the corresponding blood values are determined, and an agar-gel isoenzyme separation of the LDH is carried out. In the 11 day-old Walker carcinoma of the rat, total tumour LDH as well as total serum LDH are increased. The X-radiation does not affect the result. The M 4 isoenzyme is mainly found in the tumour tissue, to whose benefit the tumour sera also change. In tissue processing, LDH, GOT and GPT behave corresponding to their occurence in the cell compartments. The enzymes, however, appear to differ in their solution behaviour. X-radiation leeds to an early removal of these enzymes in the sense of an 'enzyme release'. (BSC/LH) [de

Nickel Solubility and Precipitation in Soils: A Thermodynamic Study

International Nuclear Information System (INIS)

Peltier, E.; Allada, R.; Navrotsky, A.; Sparks, D.

2006-01-01

The formation of mixed-metal-Al layered double hydroxide (LDH) phases similar to hydrotalcite has been identified as a significant mechanism for immobilization of trace metals in some environmental systems. These precipitate phases become increasingly stable as they age, and their formation may therefore be an important pathway for sequestration of toxic metals in contaminated soils. However, the lack of thermodynamic data for LDH phases makes it difficult to model their behavior in natural systems. In this work, enthalpies of formation for Ni LDH phases with nitrate and sulfate interlayers were determined and compared to recently published data on carbonate interlayer LDHs. Differences in the identity of the anion interlayer resulted in substantial changes in the enthalpies of formation of the LDH phases, in the order of increasing enthalpy carbonateLDH precipitates. Both mechanical mixture and solid-solution models could be used to predict the thermodynamic properties of the LDH phases. Modeling results based on these thermodynamic data indicated that the formation of LDH phases on soil mineral substrates decreased Ni solubility compared to Ni(OH)2 over pH 5-9 when soluble Al is present in the soil substrate. Over time, both of these precipitate phases will transform to more stable Ni phyllosilicates

Synthesis, anion exchange, and delamination of Co-Al layered double hydroxide: assembly of the exfoliated nanosheet/polyanion composite films and magneto-optical studies.

Science.gov (United States)

Liu, Zhaoping; Ma, Renzhi; Osada, Minoru; Iyi, Nobuo; Ebina, Yasuo; Takada, Kazunori; Sasaki, Takayoshi

2006-04-12

This paper describes a systematic study on the synthesis, anion exchange, and delamination of Co-Al layered double hydroxide (LDH), with the aim of achieving fabrication and clarifying the properties of LDH nanosheet/polyanion composite films. Co-Al-CO3 LDH hexagonal platelets of 4 mum in lateral size were synthesized by the urea method under optimized reaction conditions. The as-prepared CO3(2-)-LDH was converted to Cl- -LDH by treating with a NaCl-HCl mixed solution, retaining its high crystallinity and hexagonal platelike morphology. LDHs intercalated with a variety of anions (such as NO3-, ClO4-, acetate, lactate, dodecyl sulfate, and oleate) were further prepared from Cl- -LDH via an anion-exchange process employing corresponding salts. Exchanged products in various anion forms were found to show different delamination behaviors in formamide. Among them, best results were observed for NO3- -LDH in terms of the exfoliating degree and the quality of the exfoliated nanosheets. The delamination gave a pink transparent suspension containing well-defined nanosheets with lateral sizes of up to 2 microm. The resulting nanosheets were assembled layer-by-layer with an anionic polymer, poly(sodium styrene 4-sulfonate) (PSS), onto quartz glass substrates to produce composite films. Magnetic circular dichroism (MCD) measurements revealed that the assembled multilayer films exhibited an interesting magneto-optical response.

Protein Scaffolding for Small Molecule Catalysts

Energy Technology Data Exchange (ETDEWEB)

Baker, David [Univ. of Washington, Seattle, WA (United States)

2014-09-14

We aim to design hybrid catalysts for energy production and storage that combine the high specificity, affinity, and tunability of proteins with the potent chemical reactivities of small organometallic molecules. The widely used Rosetta and RosettaDesign methodologies will be extended to model novel protein / small molecule catalysts in which one or many small molecule active centers are supported and coordinated by protein scaffolding. The promise of such hybrid molecular systems will be demonstrated with the nickel-phosphine hydrogenase of DuBois et. al.We will enhance the hydrogenase activity of the catalyst by designing protein scaffolds that incorporate proton relays and systematically modulate the local environment of the catalyticcenter. In collaboration with DuBois and Shaw, the designs will be experimentally synthesized and characterized.

Characterization of the galactono-1,4-lactone dehydrogenase from pepper fruits and its modulation in the ascorbate biosynthesis. Role of nitric oxide

Directory of Open Access Journals (Sweden)

Marta Rodríguez-Ruiz

2017-08-01

Full Text Available Pepper fruit is one of the highest vitamin C sources of plant origin for our diet. In plants, ascorbic acid is mainly synthesized through the L-galactose pathway, being the L-galactono-1,4-lactone dehydrogenase (GalLDH the last step. Using pepper fruits, the full GalLDH gene was cloned and the protein molecular characterization accomplished. GalLDH protein sequence (586 residues showed a 37 amino acids signal peptide at the N-terminus, characteristic of mitochondria. The hydrophobic analysis of the mature protein displayed one transmembrane helix comprising 20 amino acids at the N-terminus. By using a polyclonal antibody raised against a GalLDH internal sequence and immunoblotting analysis, a 56 kDa polypeptide cross-reacted with pepper fruit samples. Using leaves, flowers, stems and fruits, the expression of GalLDH by qRT-PCR and the enzyme activity were analyzed, and results indicate that GalLDH is a key player in the physiology of pepper plants, being possibly involved in the processes which undertake the transport of ascorbate among different organs.We also report that an NO (nitric oxide-enriched atmosphere enhanced ascorbate content in pepper fruits about 40% parallel to increased GalLDH gene expression and enzyme activity. This is the first report on the stimulating effect of NO treatment on the vitamin C concentration in plants. Accordingly, the modulation by NO of GalLDH was addressed. In vitro enzymatic assays of GalLDH were performed in the presence of SIN-1 (peroxynitrite donor and S-nitrosoglutahione (NO donor. Combined results of in vivo NO treatment and in vitro assays showed that NO provoked the regulation of GalLDH at transcriptional and post-transcriptional levels, but not post-translational modifications through nitration or S-nitrosylation events promoted by reactive nitrogen species (RNS took place. These results suggest that this modulation point of the ascorbate biosynthesis could be potentially used for biotechnological

Layered double hydroxide materials coated carbon electrode: New challenge to future electrochemical power devices

International Nuclear Information System (INIS)

Djebbi, Mohamed Amine; Braiek, Mohamed; Namour, Philippe; Ben Haj Amara, Abdesslem; Jaffrezic-Renault, Nicole

2016-01-01

Highlights: • MgAl and ZnAl LDH nanosheets were chemically synthesized and deposited over carbon electrode materials. • Catalytic performance of both LDHs was investigated for Fe(II) reduction reaction. • Satisfactory results have been achieved with the MgAl LDH material. • MgAl and ZnAl LDH modified carbon felt were applied in MFC as an efficient anode catalyst. • The LDH-modified anode significantly increased power performance of MFC. - Abstract: Layered double hydroxides (LDHs) have been widely used in the past years due to their unique physicochemical properties and promising applications in electroanalytical chemistry. The present paper is going to focus exclusively on magnesium-aluminum and zinc-aluminum layered double hydroxides (MgAl & ZnAl LDHs) in order to investigate the property and structure of active cation sites located within the layer structure. The MgAl and ZnAl LDH nanosheets were prepared by the constant pH co-precipitation method and uniformly supported on carbon-based electrode materials to fabricate an LDH electrode. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy revealed the LDH form and well-crystallized materials. Wetting surface properties (hydrophilicity and hydrophobicity) of both prepared LDHs were recorded by contact angle measurement show hydrophilic character and basic property. The electrochemical performance of these hybrid materials was investigated by mainly cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques to identify the oxidation/reduction processes at the electrode/electrolyte interface and the effect of the divalent metal cations in total reactivity. The hierarchy of the modified electrode proves that the electronic conductivity of the bulk material is considerably dependent on the divalent cation and affects the limiting parameter of the overall redox process. However

Layered double hydroxide materials coated carbon electrode: New challenge to future electrochemical power devices

Energy Technology Data Exchange (ETDEWEB)

Djebbi, Mohamed Amine, E-mail: mohamed.djebbi@etu.univ-lyon1.fr [Institut des Sciences Analytiques UMR CNRS 5280, Université Claude Bernard-Lyon 1, 5 rue de la Doua, 69100 Villeurbanne (France); Laboratoire de Physique des Matériaux Lamellaires et Nano-Matériaux Hybrides, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Bizerte (Tunisia); Braiek, Mohamed [Institut des Sciences Analytiques UMR CNRS 5280, Université Claude Bernard-Lyon 1, 5 rue de la Doua, 69100 Villeurbanne (France); Namour, Philippe [Institut des Sciences Analytiques UMR CNRS 5280, Université Claude Bernard-Lyon 1, 5 rue de la Doua, 69100 Villeurbanne (France); Irstea, 5 rue de la Doua, 69100 Villeurbanne (France); Ben Haj Amara, Abdesslem [Laboratoire de Physique des Matériaux Lamellaires et Nano-Matériaux Hybrides, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Bizerte (Tunisia); Jaffrezic-Renault, Nicole [Institut des Sciences Analytiques UMR CNRS 5280, Université Claude Bernard-Lyon 1, 5 rue de la Doua, 69100 Villeurbanne (France)

2016-11-15

Highlights: • MgAl and ZnAl LDH nanosheets were chemically synthesized and deposited over carbon electrode materials. • Catalytic performance of both LDHs was investigated for Fe(II) reduction reaction. • Satisfactory results have been achieved with the MgAl LDH material. • MgAl and ZnAl LDH modified carbon felt were applied in MFC as an efficient anode catalyst. • The LDH-modified anode significantly increased power performance of MFC. - Abstract: Layered double hydroxides (LDHs) have been widely used in the past years due to their unique physicochemical properties and promising applications in electroanalytical chemistry. The present paper is going to focus exclusively on magnesium-aluminum and zinc-aluminum layered double hydroxides (MgAl & ZnAl LDHs) in order to investigate the property and structure of active cation sites located within the layer structure. The MgAl and ZnAl LDH nanosheets were prepared by the constant pH co-precipitation method and uniformly supported on carbon-based electrode materials to fabricate an LDH electrode. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy revealed the LDH form and well-crystallized materials. Wetting surface properties (hydrophilicity and hydrophobicity) of both prepared LDHs were recorded by contact angle measurement show hydrophilic character and basic property. The electrochemical performance of these hybrid materials was investigated by mainly cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques to identify the oxidation/reduction processes at the electrode/electrolyte interface and the effect of the divalent metal cations in total reactivity. The hierarchy of the modified electrode proves that the electronic conductivity of the bulk material is considerably dependent on the divalent cation and affects the limiting parameter of the overall redox process. However

Enhanced mechanical and thermal properties of polystyrene nanocomposites prepared using organo-functionalized NiAl layered double hydroxide via melt intercalation technique

Directory of Open Access Journals (Sweden)

Kelothu Suresh

2017-06-01

Full Text Available The article reports upon the preparation and characterization of organo-functionalized NiAl layered double hydroxide (LDH-polystyrene (PS nanocomposites. Initially, pristine NiAl LDH was synthesized via the co-precipitation technique and was subsequently treated using sodium dodecyl sulfate to obtain organo-functionalized NiAl LDH (ONiAl LDH. PS nanocomposites were fabricated by melt intercalation using a twin screw extruder in presence of ONiAl LDH nanofiller (1, 3, 5, and 7 wt.%. The PS nanocomposites were characterized for their structural, thermal and mechanical properties. The dispersion and morphology of the obtained PS nanocomposites were investigated by X-ray diffraction (XRD and transmission electron microscopy (TEM. Mechanical and thermal properties of the PS nanocomposites as a function of LDH content were examined by tensile tests, thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. The XRD and TEM results revealed the formation of an exfoliated structure of the PS nanocomposite with 1 wt.% ONiAl LDH loading. The maximum improvements of the mechanical and thermal properties of the nanocomposites with ONiAl LDH loading over pristine PS included tensile strength = 34.5% (1 wt.%, thermal decomposition temperatures (T15% = 27.4 °C (7 wt.%, and glass transition temperature (Tg = 4.3 °C (7 wt.%. The PS nanocomposites possessed higher mechanical strength and thermal degradation resistance compared to the pristine PS. The activation energy (Ea and reaction mechanism with respect to thermal degradation of the pristine PS and its nanocomposites were evaluated by the Coats-Redfern and Criado model, respectively.

Dynamics of Intercalation/De-Intercalation of Rhodamine B during the Polymorphic Transformation of CdAl Layered Double Hydroxide to the Brucite-Like Cadmium Hydroxide

KAUST Repository

Saliba, Daniel

2016-06-23

Cadmium-Aluminum layered double hydroxide (CdAl LDH) is thermodynamically unstable and transforms to Cd(OH)2 and Al(OH)3 in a short period of time. We present a reaction-diffusion framework that enables us to use in situ steady-state fluorescence spectroscopy to study the kinetics of intercalation of a fluorescent probe (Rhodamine B (RhB)) during the formation of the CdAl LDH and its de-intercalation upon the conversion of the LDH phase to the β phase (Cd(OH)2). The method involves the diffusion of sodium hydroxide into a hydrogel gel matrix containing the aluminum and cadmium ions as well as the species we wish to incorporate in the interlayers of the LDH. The existence of RhB between the LDH layers and its expel during the transition into the β phase are proved via fluorescence microscopy, XRD and ssNMR. The activation energies of intercalation and de-intercalation of RhB are computed and show dependence on the cationic ratio of the corresponding LDH. We find that the energies of de- intercalation are systematically higher than those of intercalation proving that the dyes are stabilized due to the probe-brucite sheets interactions.

Gold Nanoparticles on Layered Double Hydroxide Nanosheets and Its Electrocatalysis for Glucose Oxidation

Energy Technology Data Exchange (ETDEWEB)

Cho, Hye Ran; Lee, Jong Hyeon [The Catholic University of Korea, Bucheon (Korea, Republic of); Cho, Se Hee; Ji, Hong Geun [H and A PharmaChem, Bucheon (Korea, Republic of)

2016-03-15

We developed a new way to form the well-defined nanocomposite of Au NPs and exfoliated LDH nanosheet by in situ chemical reduction with NaBH{sub 4}. The optical and structural studies indicate that the Au NPs are highly dispersed and immobilized on the surface of LDH nanosheets. The Au/LDH nanosheet exhibited an excellent electrocatalysis toward glucose oxidation reaction. The results strongly demonstrate that the nanoscopic natures and dense positive charges of LDH nanosheet effectively stabilized the Au NPs to maintain their inherent properties during the synthesis and the electrocatalysis. The use of the double hydroxide nanosheets as nanoscopic support materials for the transition-metal NPs will dramatically improve their functionalities in heterogeneous catalysis. Recently, two-dimensional nanosheet of exfoliated layered double hydroxide (LDH) has emerged as a new type of solid support to immobilize the diverse metal NPs because of the large metal hydroxide area, good biochemical stability, and highly charged positive potential of 1- to 2-nm thick LDH layers. LDHs consist of a continuous stack of positively charged metal hydroxide layers with counter anions and water molecules placed in interlayer spaces.

Dynamics of Intercalation/De-Intercalation of Rhodamine B during the Polymorphic Transformation of CdAl Layered Double Hydroxide to the Brucite-Like Cadmium Hydroxide

KAUST Repository

Saliba, Daniel; Ezzeddine, Alaa; Emwas, Abdul-Hamid M.; Khashab, Niveen M.; Al-Ghoul, Mazen

2016-01-01

Cadmium-Aluminum layered double hydroxide (CdAl LDH) is thermodynamically unstable and transforms to Cd(OH)2 and Al(OH)3 in a short period of time. We present a reaction-diffusion framework that enables us to use in situ steady-state fluorescence spectroscopy to study the kinetics of intercalation of a fluorescent probe (Rhodamine B (RhB)) during the formation of the CdAl LDH and its de-intercalation upon the conversion of the LDH phase to the β phase (Cd(OH)2). The method involves the diffusion of sodium hydroxide into a hydrogel gel matrix containing the aluminum and cadmium ions as well as the species we wish to incorporate in the interlayers of the LDH. The existence of RhB between the LDH layers and its expel during the transition into the β phase are proved via fluorescence microscopy, XRD and ssNMR. The activation energies of intercalation and de-intercalation of RhB are computed and show dependence on the cationic ratio of the corresponding LDH. We find that the energies of de- intercalation are systematically higher than those of intercalation proving that the dyes are stabilized due to the probe-brucite sheets interactions.

Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

Energy Technology Data Exchange (ETDEWEB)

Arratia-Quijada, Jenny [Departamento de Ciencias de la Salud, Centro Universitario Tonalá, Universidad de Guadalajara, Av. Nuevo Periférico No. 555, C.P. 48525, Tonalá, Jalisco (Mexico); Sánchez Jiménez, Cecilia [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, St. Petersburg State University, Universitetskiy pr. 26, 198504 St. Petersburg (Russian Federation); NMR Core Lab, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Pérez Centeno, Armando; Ceja Andrade, Israel [Departamento de Física, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

2016-01-15

Graphical abstract: - Highlights: • LDH structure including dysprosium was prepared by co-precipitation. • LDH was capable to produce contrast in the T1 mode of MRI. • LDH were intercalated with folate, ibuprofen and gallate ions. - Abstract: A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

International Nuclear Information System (INIS)

Arratia-Quijada, Jenny; Sánchez Jiménez, Cecilia; Gurinov, Andrey; Pérez Centeno, Armando; Ceja Andrade, Israel; Carbajal Arízaga, Gregorio Guadalupe

2016-01-01

Graphical abstract: - Highlights: • LDH structure including dysprosium was prepared by co-precipitation. • LDH was capable to produce contrast in the T1 mode of MRI. • LDH were intercalated with folate, ibuprofen and gallate ions. - Abstract: A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

DNA-enhanced peroxidase-like activity of layered double hydroxide nanosheets and applications in H2O2 and glucose sensing.

Science.gov (United States)

Chen, Lijian; Sun, Kaifang; Li, Peipei; Fan, Xianzhong; Sun, Jianchao; Ai, Shiyun

2013-11-21

LDH nanosheets were obtained via continuous impaction and exfoliation by herring sperm DNA molecules using a constant vibration method. DNA-LDH nanohybrids were composed by electrostatic forces and they exhibited DNA-enhanced peroxidase-like activity. The morphology and structure of DNA-LDH nanohybrids were analyzed by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and atomic force microscopy (AFM) characterization. On the basis of the high catalytic activity of DNA/CuAl-LDH nanosheets, a rapid, sensitive, and convenient approach was developed for colorimetric detection of H2O2 and blood glucose. This method can be potentially applied in medical diagnostics and biotechnology fields.

Enhanced activity of CaFeMg layered double hydroxides-supported gold nanodendrites for the electrochemical evolution of oxygen and hydrogen in alkaline media

Science.gov (United States)

Havakeshian, Elaheh; Salavati, Hossein; Taei, Masoumeh; Hasheminasab, Fatemeh; Seddighi, Mohadeseh

2018-02-01

In this study, Au was electrodeposited on a support of CaFeMg layered double hydroxide and then, its catalytic activity was investigated for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Field emission scanning electron microscopy images showed that a uniform porous film of aggregated nano-particles of the LDH has been decorated with Au nanodendrite-like structures (AuNDs@LDH). The results obtained from polarization curves, Tafel plots and electrochemical impedance spectroscopy showed that the AuNDs@LDH exhibits lower overpotential, higher current density, faster kinetics and enhanced stability for both of the OER and HER, in comparison with the single AuNPs and LDH catalysts.

Hidróxidos duplos lamelares: nanopartículas inorgânicas para armazenamento e liberação de espécies de interesse biológico e terapêutico Layered double hydroxides: inorganic nanoparticles for storage and release of species of biological and therapeutic interest

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Vanessa R. R. Cunha

2010-01-01

Full Text Available Studies about the inorganic nanoparticles applying for non-viral release of biological and therapeutic species have been intensified nowadays. This work reviews the preparation strategies and application of layered double hydroxides (LDH as carriers for storing, carrying and control delivery of intercalated species as drugs and DNA for gene therapy. LDH show low toxicity, biocompatibility, high anion exchange capacity, surface sites for functionalization, and a suitable equilibrium between chemical stability and biodegradability. LDH can increase the intercalated species stability and promote its sub-cellular uptake for biomedical purposes. Concerning the healthy field, LDH have been evaluated for clinical diagnosis as a biosensor component.

Removal of lead from aqueous solution on glutamate intercalated layered double hydroxide

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Shen Yanming

2017-05-01

Full Text Available Glutamate intercalated Mg–Al layered double hydroxide (LDH was prepared by co-precipitation and the removal of Pb2+ in the aqueous solution was investigated. The prepared samples were characterized by XRD, FT-IR and SEM. It was shown that glutamate can intercalate into the interlayer space of Mg–Al LDH. The glutamate intercalated Mg–Al LDH can effectively adsorb Pb2+ in the aqueous solution with an adsorption capacity of 68.49 mg g−1. The adsorption of Pb2+ on glutamate intercalated Mg–Al LDH fitted the pseudo-second-order kinetics model and the isotherm can be well defined by Langmuir model.

Method for the enzymatic production of hydrogen

Science.gov (United States)

Woodward, J.; Mattingly, S.M.

1999-08-24

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

Development of a photoelectrochemical lactic dehydrogenase biosensor using multi-wall carbon nanotube-TiO2 nanoparticle composite as coenzyme regeneration tool

International Nuclear Information System (INIS)

Liu, Xiaoqiang; Yan, Rui; Zhu, Jie; Huo, Xiaohe; Wang, Xinhai

2015-01-01

Highlights: •Multi-wall Carbon Nanotube-TiO 2 nanoparticle composite was synthesized by hydrothermal method •The composite was characterized by TEM, XRD, FT-IR •A photoelectrochemical (PEC) lactic dehydrogenase (LDH) biosensor was developed based on the composite •The composite acts as both coenzyme regeneration tool and immobilization material •The PEC biosensor shows superiority over the electrochemical LDH biosensors in analytical performance -- Abstract: A novel photoelectrochemical (PEC) lactic dehydrogenase (LDH) biosensor was developed based on a multi-wall carbon nanotube (MWCNT)-TiO 2 nanoparticle (TNP) composite platform. This composite platform can not only aid in regeneration of nicotinamide adenine dinucleotide (NAD + ) in the enzymatic cycle, but also immobilize enzymes on electrode surface. TNPs were grown on MWCNT surface through a hydrothermal method and the composite was characterized by various spectroscopic techniques. The electrochemical performance of the LDH biosensors has demonstrated that the composite is a feasible immobilization matrix for LDH. The PEC experiments have confirmed that NAD + can be regenerated by the holes produced by irradiating MWCNT-TNP composite to fulfill the enzyme catalytic cycle. The analytical performance of the PEC LDH biosensor was studied by measuring its photocurrents. The dynamic range, sensitivity and limit of detection of the biosensor were estimated to be 0.5 to 120 μM, 0.0242 μA μM −1 and 0.1 μM respectively, which are superior to those of electrochemical LDH biosensors

Nickel/cobalt layered double hydroxide hollow microspheres with hydrangea-like morphology for high-performance supercapacitors

International Nuclear Information System (INIS)

Tao, Yan; Ruiyi, Li; Tingting, Yang; Zaijun, Li

2015-01-01

Graphical abstract: We report a new template synthesis of nickel/cobalt layered double hydroxides (Ni/Co-LDH) without any adscititious alkali source, oxidant and step for removal of the template. The perfect match between generation rate of Ni/Co-LDH nanoflakes and removal rate of template creates elaborate three-dimensional architecture with well-defined hollow interior and hydrangea-like exterior. The unique structure improves faradaic redox reaction and mass transfer during the redox process, thus the Ni/Co-LDH electrode provides excellent electrochemical performance for supercapacitors. - Highlights: • The study demonstrated a new strategy for template synthesis of Ni/Co-LDH without any adscititious alkali source, oxidant and step for removal of the template. • The perfect match between generation rate of Ni/Co-LDH nanoflakes and removal rate of SiO 2 template create hollow microspheres with hydrangea-like morphology. • The unique structure of Ni/Co-LDH will greatly improve faradaic redox reaction and mass transfer during the redox process. • The Ni/Co-LDH electrode displays high specific capacitance, good charge/discharge capability, large energy density and superior cycle stability. • The study provides a prominent approach to fabricate various hollow nanomaterials for supercapacitors, Li-ion batteries, catalyst and sensors. - Abstract: Electroactive materials with hollow nanostructures received great attractiveness due to large surface area, low density and superior structure permeablity. The paper reported a new template synthesis of nickel/cobalt layered double hydroxides (Ni/Co-LDH) without any adscititious alkali source, oxidant and step for removal of the template. Nickel nitrate, cobalt nitrate and SiO 2 nanosphere were dispersed in an ethanol solution. Then, the mixed soution was heated at 160 °C for 6 h to obtain Ni/Co-LDH product. During the process, ethanol and nitrate underwent a redox reaction releasing hydroxide ions, which will react

Structure and thermal evolution of Mg-Al layered double hydroxide containing interlayer organic glyphosate anions

Energy Technology Data Exchange (ETDEWEB)

Li Feng; Zhang Lihong; Evans, David G.; Forano, Claude; Duan Xue

2004-12-15

Layered double hydroxide (LDH) with the Mg{sup 2+}/Al{sup 3+} molar ratio of 2.0 containing interlayer organic pesticide glyphosate anions (MgAl-Gly-LDH) has been synthesized by the use of anion exchange and coprecipitation routes. Intercalation experiments with glyphosate (Gly) reveal a correlation between the temperatures for thermal treatments and the types of reaction it undergoes with Gly. The grafting of the Gly anion onto hydroxylated sheets of LDH by moderate thermal treatments (hydrothermal treatments and calcinations) was confirmed by a combination of several techniques, including powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry analysis (TGA-DTG), and {sup 31}P nuclear magnetic resonance (NMR). The thermal decomposition of MgAl-Gly-LDH results in the removal of loosely held interlayer water, grafting reaction between the interlayer anions and hydroxyl groups on the lattice of LDH, dehydroxylation of the lattice and decomposition of the interlayer species in succession, thus leading to a variety of crystallographic transitions.

Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

Science.gov (United States)

Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

2015-12-01

A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

Thermokinetic study of the rehydration process of a calcined MgAl-layered double hydroxide.

Science.gov (United States)

Pfeiffer, Heriberto; Lima, Enrique; Lara, Víctor; Valente, Jaime S

2010-03-16

The rehydration process of a calcined MgAl-layered double hydroxide (LDH) with a Mg/Al molar ratio of 3 was systematically analyzed at different temperatures and relative humidity. Qualitative and quantitative experiments were done. In the first set of samples, the temperature or the relative humidity was varied, fixing the second variable. Both adsorption and absorption phenomena were present; absorption process was associated to the LDH regeneration. Of course, in all cases the LDH regeneration was confirmed by other techniques such as TGA, solid state NMR, and SAXS. In the second set of experiments, a kinetic analysis was performed, the results allowed to obtain different activation enthalpies for the LDH regeneration as a function of the relative humidity. The activation enthalpies varied from 137.6 to 83.3 kJ/mol as a function of the relative humidity (50 and 80%, respectively). All these experiments showed that LDH regeneration is highly dependent on the temperature and relative humidity.

Efficient carbon dots/NiFe-layered double hydroxide/BiVO4 photoanodes for photoelectrochemical water splitting

Science.gov (United States)

Lv, Xiaowei; Xiao, Xin; Cao, Minglei; Bu, Yi; Wang, Chuanqing; Wang, Mingkui; Shen, Yan

2018-05-01

Modification of semiconductor photoanodes with oxygen evolution catalyst (OEC) is an effective approach for improving photoelectrochemical (PEC) water splitting efficiency. In the configuration, how to increase the activity of OEC is crucial to further improve PEC performance. Herein, a ternary photoanode system was designed to enhance PEC efficiency of photoelectrodes through introducing carbon dots (CDs), NiFe-layered double hydroxide (NiFe-LDH) nanosheets on BiVO4 particles. Systematic research shows that NiFe-LDH serves as an OEC which accelerates oxygen evolution kinetics, while the introduction of CDs can further reduce charge transfer resistance and overpotential for oxygen evolution. Under the synergistic effect of NiFe-LDH and CDs, the photocurrent and incident photon to current conversion efficiency (IPCE) of the resulting CDs/NiFe-LDH/BiVO4 photoanode is improved significantly than those of the NiFe-LDH/BiVO4 electrode. Consequently, such a ternary heterostructure could be an alternative way to further enhance PEC water splitting performance.

Mechanochemical synthesis of dodecyl sulfate anion (DS-) intercalated Cu-Al layered double hydroxide

Science.gov (United States)

Qu, Jun; He, Xiaoman; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

2017-12-01

Dodecyl sulfate anion (DS-) was successfully intercalated into the gallery space of Cu-Al layered double hydroxides (LDH) by a non-heating mechanochemical route, in which basic cupric carbonate (Cu2(OH)2CO3) and aluminum hydroxide (Al(OH)3) were first dry ground and then agitated in SDS solution under ambient environment. The organics modified Cu-Al LDH showed good adsorption ability toward 2,4-dichlorophenoxyacetic acid (2, 4-D). The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), CHS elemental analysis and Scanning electron microscopy (SEM). The LDH precursor prepared by ball-milling could directly react with SDS molecules forming a pure phase of DS- pillared Cu-Al LDH, which was not observed with the LDH product through the ion-exchange of DS- at room temperature. The process introduced here may be applied to manufacture other types of organic modified composites for pollutants removal and other applications.

Incorporation of layered double nanomaterials in thin film nanocomposite nanofiltration membrane for magnesium sulphate removal

Science.gov (United States)

Hanis Tajuddin, Muhammad; Yusof, Norhaniza; Salleh, Wan Norharyati Wan; Fauzi Ismail, Ahmad; Hanis Hayati Hairom, Nur; Misdan, Nurasyikin

2018-03-01

Thin film nanocomposite (TFN) membrane with copper-aluminium layered double hydroxides (LDH) incorporated into polyamide (PA) selective layer has been prepared for magnesium sulphate salt removal. 0, 0.05, 0.1, 0.15, 0.2 wt% of LDH were dispersed in the trimesoyl chloride (TMC) in n-hexane as organic solution and embedded into PA layer during interfacial polymerization with piperazine. The fabricated membranes were further characterized to evaluate its morphological structure and membrane surface hydrophilicity. The TFN membranes performance were evaluated with divalent salt magnesium sulphate (MgSO4) removal and compared with thin film composite (TFC). The morphological structures of TFN membranes were altered and the surface hydrophilicity were enhanced with addition of LDH. Incorporation of LDH has improved the permeate water flux by 82.5% compared to that of TFC membrane with satisfactory rejection of MgSO4. This study has experimentally validated the potential of LDH to improve the divalent salt separation performance for TFN membranes.

Enhancement of the coercivity in Co-Ni layered double hydroxides by increasing basal spacing.

Science.gov (United States)

Zhang, Cuijuan; Tsuboi, Tomoya; Namba, Hiroaki; Einaga, Yasuaki; Yamamoto, Takashi

2016-09-14

The magnetic properties of layered double hydroxides (LDH) containing transition metal ions can still develop, compared with layered metal hydroxide salts which exhibit structure-dependent magnetism. In this article, we report the preparation of a hybrid magnet composed of Co-Ni LDH and n-alkylsulfonate anions (Co-Ni-CnSO3 LDH). As Co-Ni LDH is anion-exchangeable, we can systematically control the interlayer spacing by intercalating n-alkylsulfonates with different carbon numbers. The magnetic properties were examined with temperature- and field-dependent magnetization measurements. As a result, we have revealed that the coercive field depends on the basal spacing. It is suggested that increasing the basal spacing varies the competition between the in-plane superexchange interactions and long-range out-of-plane dipolar interactions. Moreover, a jump in the coercive field at around 20 Å of the basal spacing is assumed to be the modification of the magnetic ordering in Co-Ni-CnSO3 LDH.

Incorporation of layered double nanomaterials in thin film nanocomposite nanofiltration membrane for magnesium sulphate removal

Directory of Open Access Journals (Sweden)

Tajuddin Muhammad Hanis

2018-01-01

Full Text Available Thin film nanocomposite (TFN membrane with copper-aluminium layered double hydroxides (LDH incorporated into polyamide (PA selective layer has been prepared for magnesium sulphate salt removal. 0, 0.05, 0.1, 0.15, 0.2 wt% of LDH were dispersed in the trimesoyl chloride (TMC in n-hexane as organic solution and embedded into PA layer during interfacial polymerization with piperazine. The fabricated membranes were further characterized to evaluate its morphological structure and membrane surface hydrophilicity. The TFN membranes performance were evaluated with divalent salt magnesium sulphate (MgSO4 removal and compared with thin film composite (TFC. The morphological structures of TFN membranes were altered and the surface hydrophilicity were enhanced with addition of LDH. Incorporation of LDH has improved the permeate water flux by 82.5% compared to that of TFC membrane with satisfactory rejection of MgSO4. This study has experimentally validated the potential of LDH to improve the divalent salt separation performance for TFN membranes.

Synthesis and In Vitro Characterization of Fe3+-Doped Layered Double Hydroxide Nanorings as a Potential Imageable Drug Delivery System

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Lijun Wang

2017-09-01

Full Text Available Highly dispersed Fe3+-doped layered double hydroxide (LDH-Fe nanorings were obtained by a simple coprecipitation-acid etching approach. The morphology, structure, magnetic resonance imaging (MRI performance in vitro, drug loading and releasing, Fe3+ leakage, and cytotoxicity of the as-prepared LDH-Fe nanorings were characterized. The LDH-Fe nanorings showed good water dispersity and a well-crystallized structure. The DLS average size of nanoparticles was measured to be 94.5 nm. Moreover, the MRI tests showed a favourable T1-weighted MRI performance of the LDH-Fe nanoring with r1 values of 0.54 and 1.68, and low r2/r1 ratios of 10.1 and 6.3, pre- and after calcination, respectively. The nanoparticles also showed high model drug (ibuprofen loading capacities, low Fe3+ leakage, and negligible cytotoxicity. All these results demonstrate the potential of LDH-Fe nanorings as an imageable drug delivery system.

Kinetic characterization of recombinant Bacillus coagulans FDP-activated l-lactate dehydrogenase expressed in Escherichia coli and its substrate specificity.

Science.gov (United States)

Jiang, Ting; Xu, Yanbing; Sun, Xiucheng; Zheng, Zhaojuan; Ouyang, Jia

2014-03-01

Bacillus coagulans is a homofermentative, acid-tolerant and thermophilic sporogenic lactic acid bacterium, which is capable of producing high yields of optically pure lactic acid. The l-(+)-lactate dehydrogenase (l-LDH) from B. coagulans is considered as an ideal biocatalyst for industrial production. In this study, the gene ldhL encoding a thermostable l-LDH was amplified from B. coagulans NL01 genomic DNA and successfully expressed in Escherichia coli BL21 (DE3). The recombinant enzyme was partially purified and its enzymatic properties were characterized. Sequence analysis demonstrated that the l-LDH was a fructose 1,6-diphosphate-activated NAD-dependent lactate dehydrogenase (l-nLDH). Its molecular weight was approximately 34-36kDa. The Km and Vmax values of the purified l-nLDH for pyruvate were 1.91±0.28mM and 2613.57±6.43μmol(minmg)(-1), respectively. The biochemical properties of l-nLDH showed that the specific activity were up to 2323.29U/mg with optimum temperature of 55°C and pH of 6.5 in the pyruvate reduction and 351.01U/mg with temperature of 55°C and pH of 11.5 in the lactate oxidation. The enzyme also showed some activity in the absence of FDP, with a pH optimum of 4.0. Compared to other lactic acid bacterial l-nLDHs, the enzyme was found to be relatively stable at 50°C. Ca(2+), Ba(2+), Mg(2+) and Mn(2+) ions had activated effects on the enzyme activity, and the enzyme was greatly inhibited by Ni(2+) ion. Besides these, l-nLDH showed the higher specificity towards pyruvate esters, such as methyl pyruvate and ethyl pyruvate. Copyright © 2014 Elsevier Inc. All rights reserved.

Stimulation of d- and l-lactate dehydrogenases transcriptional levels in presence of diammonium hydrogen phosphate resulting to enhanced lactic acid production by Lactobacillus strain.

Science.gov (United States)

Singhvi, Mamata; Zendo, Takeshi; Iida, Hiroshi; Gokhale, Digambar; Sonomoto, Kenji

2017-12-01

The present study revealed the effect of nitrogen sources on lactic acid production and stimulation of d- and l-lactate dehydrogenases (LDH) of parent Lactobacillus lactis NCIM 2368 and its mutant RM2-24 generated after UV mutagenesis. Both the parent and mutant strains were evaluated for d-lactic acid production in control and modified media. The modified media did not show remarkable effect on lactic acid production in case of parent whereas mutant exhibited significant enhancement in d-lactic acid production along with the appearance of l-lactic acid in the broth. Both LDH activities and specific activities were found to be higher in mutant than the parent strain. These results suggested that the diammonium hydrogen phosphate in modified media triggered the expression of LDH genes leading to enhanced lactic acid production. This observation has been proved by studying the expression levels of d- and l-LDH genes of parent and mutant in control and modified media using quantitative RT-PCR technique. In case of mutant, the transcriptional levels of d-LDH and l-LDH increased ∼17 fold and ∼1.38 fold respectively in modified medium compared to the values obtained with control medium. In case of parent, no significant change in transcriptional levels of d- and l-LDH was found when the cells were grown in either control medium or modified medium. This study suggested that the mutant, RM2-24 has l-LDH gene which is expressed in presence of (NH 4 ) 2 HPO 4 resulting in l-lactic acid production. Co-production of l-lactic acid in d-lactic acid fermentation may be detrimental in the PLA production. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Lactate dehydrogenase-B is silenced by promoter methylation in a high frequency of human breast cancers.

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Nicola J Brown

Full Text Available Under normoxia, non-malignant cells rely on oxidative phosphorylation for their ATP production, whereas cancer cells rely on Glycolysis; a phenomenon known as the Warburg effect. We aimed to elucidate the mechanisms contributing to the Warburg effect in human breast cancer.Lactate Dehydrogenase (LDH isoenzymes were profiled using zymography. LDH-B subunit expression was assessed by reverse transcription PCR in cells, and by Immunohistochemistry in breast tissues. LDH-B promoter methylation was assessed by sequencing bisulfite modified DNA.Absent or decreased expression of LDH isoenzymes 1-4, were seen in T-47D and MCF7 cells. Absence of LDH-B mRNA was seen in T-47D cells, and its expression was restored following treatment with the demethylating agent 5'Azacytadine. LDH-B promoter methylation was identified in T-47D and MCF7 cells, and in 25/25 cases of breast cancer tissues, but not in 5/5 cases of normal breast tissues. Absent immuno-expression of LDH-B protein (<10% cells stained, was seen in 23/26 (88% breast cancer cases, and in 4/8 cases of adjacent ductal carcinoma in situ lesions. Exposure of breast cancer cells to hypoxia (1% O(2, for 48 hours resulted in significant increases in lactate levels in both MCF7 (14.0 fold, p = 0.002, and T-47D cells (2.9 fold, p = 0.009, but not in MDA-MB-436 (-0.9 fold, p = 0.229, or MCF10AT (1.2 fold, p = 0.09 cells.Loss of LDH-B expression is an early and frequent event in human breast cancer occurring due to promoter methylation, and is likely to contribute to an enhanced glycolysis of cancer cells under hypoxia.

Unique flexibility in energy metabolism allows mycobacteria to combat starvation and hypoxia.

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Michael Berney

Full Text Available Mycobacteria are a group of obligate aerobes that require oxygen for growth, but paradoxically have the ability to survive and metabolize under hypoxia. The mechanisms responsible for this metabolic plasticity are unknown. Here, we report on the adaptation of Mycobacterium smegmatis to slow growth rate and hypoxia using carbon-limited continuous culture. When M. smegmatis is switched from a 4.6 h to a 69 h doubling time at a constant oxygen saturation of 50%, the cells respond through the down regulation of respiratory chain components and the F1Fo-ATP synthase, consistent with the cells lower demand for energy at a reduced growth rate. This was paralleled by an up regulation of molecular machinery that allowed more efficient energy generation (i.e. Complex I and the use of alternative electron donors (e.g. hydrogenases and primary dehydrogenases to maintain the flow of reducing equivalents to the electron transport chain during conditions of severe energy limitation. A hydrogenase mutant showed a 40% reduction in growth yield highlighting the importance of this enzyme in adaptation to low energy supply. Slow growing cells at 50% oxygen saturation subjected to hypoxia (0.6% oxygen saturation responded by switching on oxygen scavenging cytochrome bd, proton-translocating cytochrome bc1-aa3 supercomplex, another putative hydrogenase, and by substituting NAD+-dependent enzymes with ferredoxin-dependent enzymes thus highlighting a new pattern of mycobacterial adaptation to hypoxia. The expression of ferredoxins and a hydrogenase provides a potential conduit for disposing of and transferring electrons in the absence of exogenous electron acceptors. The use of ferredoxin-dependent enzymes would allow the cell to maintain a high carbon flux through its central carbon metabolism independent of the NAD+/NADH ratio. These data demonstrate the remarkable metabolic plasticity of the mycobacterial cell and provide a new framework for understanding their

Synthesis, characterization, and immune efficacy of layered double hydroxide@SiO2 nanoparticles with shell-core structure as a delivery carrier for Newcastle disease virus DNA vaccine

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Zhao K

2015-04-01

Full Text Available Kai Zhao,1,* Guangyu Rong,1,2,* Chen Guo,1 Xiaomei Luo,1 Hong Kang,1 Yanwei Sun,1,3 Chunxiao Dai,4 Xiaohua Wang,1 Xin Wang,1 Zheng Jin,4 Shangjin Cui,3 Qingshen Sun1 1Key Laboratory of Microbiology, School of Life Science, Heilongjiang University, Harbin, People’s Republic of China; 2Department of Avian Infectious Disease, Shanghai Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Shanghai, People’s Republic of China; 3Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People’s Republic of China; 4Key Laboratory of Chemical Engineering Process and Technology for High-efficiency Conversion, Heilongjiang University, Harbin, People’s Republic of China *These authors contributed equally to this work Abstract: Layered double hydroxide (LDH@SiO2 nanoparticles were developed as a delivery carrier for the plasmid DNA expressing the Newcastle disease virus F gene. The LDH was hydrotalcite-like materials. The plasmid DNA encapsulated in the LDH@SiO2 nanoparticles (pFDNA-LDH@SiO2-NPs was prepared by the coprecipitation method, and the properties of pFDNA-LDH@SiO2-NPs were characterized by transmission electron microscopy, zeta potential analyzer, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The results demonstrated that the pFDNA-LDH@SiO2-NPs had a regular morphology and high stability with a mean diameter of 371.93 nm, loading capacity of 39.66%±0.45%, and a zeta potential of +31.63 mV. A release assay in vitro showed that up to 91.36% of the total plasmid DNA could be sustainably released from the pFDNA-LDH@SiO2-NPs within 288 hours. The LDH@SiO2 nanoparticles had very low toxicity. Additionally, their high transfection efficiency in vitro was detected by fluorescent microscopy. Intranasal immunization of specific pathogen-free chickens with pFDNA-LDH@SiO2-NPs

Tunable Properties of Exfoliated Polyvinylalcohol Nanocomposites by In Situ Coprecipitation of Layered Double Hydroxides

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Liu, Jiajia; Yuen, Richard K. K.; Hu, Yuan

2017-10-01

Poly(vinyl alcohol) (PVA) nanocomposites were prepared by a “one step” method based on the coprecipitation of layered double hydroxide (LDH) nanosheets in the polymer aqueous solution. The morphology, fire resistance properties, mechanical and optical properties of the PVA/LDH nanocomposites were studied. The LDH nanosheets were homogeneously dispersed in the PVA matrix as indicated by X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) characterization. Meanwhile, the peak of heat release rate (pHRR) and total heat release (THR) were decreased by 58% and 28%, respectively. Storage modulus at 30 °C was increased, and the transmittance of more than 90% at the visible region was obtained upon addition of 5 wt% LDH.

Preparation of hydroxide ion conductive KOH–layered double hydroxide electrolytes for an all-solid-state iron–air secondary battery

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Taku Tsuneishi

2014-06-01

Full Text Available Anion conductive solid electrolytes based on Mg–Al layered double hydroxide (LDH were prepared for application in an all-solid-state Fe–air battery. The ionic conductivity and the conducting ion species were evaluated from impedance and electromotive force measurements. The ion conductivity of LDH was markedly enhanced upon addition of KOH. The electromotive force in a water vapor concentration cell was similar to that of an anion-conducting polymer membrane. The KOH–LDH obtained was used as a hydroxide ion conductive electrolyte for all-solid-state Fe–air batteries. The cell performance of the Fe–air batteries was examined using a mixture of KOH–LDH and iron-oxide-supported carbon as the negative electrode.

Potential sustainable slow release fertilizers obtained by mechanochemical activation of layered double hydroxides and K{sub 2}HPO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Borges, Roger; Wypych, Fernando, E-mail: 1roger.borges@gmail.com [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil); Prevot, Vanessa; Forano, Claude [Universite Blaise Pascal, Clermont-Ferrand (France)

2016-07-01

Full text: This study describes the preliminary results on the development of potential sustainable slow-release fertilizer (SSRF), obtained by mechanochemical activation of mixtures of calcined layered double hydroxides (LDH) Mg{sub 2}Al-CO{sub 3} and Mg{sub 2}Fe-CO{sub 3} and K{sub 2}HPO{sub 4}. The effect of LDH temperature of calcination, milling time (using a high-energy balls mill) and LDH:K{sub 2}HPO{sub 4} molar were investigated. The samples were characterized by XRD and FTIR. Phosphate release essays shown that its solubility is reduced, while the solubility of amorphous structures from LDH can be increased, which characterize the expected slow release behavior of a SSRF. (author)

A Tale of Two Gases: Isotope Effects Associated with the Enzymatic Production of H2 and N2O

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Yang, H.; Gandhi, H.; Kreuzer, H. W.; Moran, J.; Hill, E. A.; McQuarters, A.; Lehnert, N.; Ostrom, N. E.; Hegg, E. L.

2014-12-01

Stable isotopes can provide considerable insight into enzymatic mechanisms and fluxes in various biological processes. In our studies, we used stable isotopes to characterize both enzyme-catalyzed H2 and N2O production. H2 is a potential alternative clean energy source and also a key metabolite in many microbial communities. Biological H2 production is generally catalyzed by hydrogenases, enzymes that combine protons and electrons to produce H2 under anaerobic conditions. In our study, H isotopes and fractionation factors (α) were used to characterize two types of hydrogenases: [FeFe]- and [NiFe]-hydrogenases. Due to differences in the active site, the α associated with H2 production for [FeFe]- and [NiFe]-hydrogenases separated into two distinct clusters (αFeFe > αNiFe). The calculated kinetic isotope effects indicate that hydrogenase-catalyzed H2 production has a preference for light isotopes, consistent with the relative bond strengths of O-H and H-H bonds. Interestingly, the isotope effects associated with H2 consumption and H2-H2O exchange reactions were also characterized, but in this case no specific difference was observed between the different enzymes. N2O is a potent greenhouse gas with a global warming potential 300 times that of CO2, and the concentration of N2O is currently increasing at a rate of ~0.25% per year. Thus far, bacterial and fungal denitrification processes have been identified as two of the major sources of biologically generated N2O. In this study, we measured the δ15N, δ18O, δ15Nα (central N atom in N2O), and δ15Nβ (terminal N atom in N2O) of N2O generated by purified fungal P450 nitric oxide reductase (P450nor) from Histoplasma capsulatum. We observed normal isotope effects for δ18O and δ15Nα, and inverse isotope effects for bulk δ15N (the average of Nα and Nβ) and δ15Nβ. The observed isotope effects have been used in conjunction with DFT calculations to provide important insight into the mechanism of P450nor. Similar

DFT-Based Simulation and Experimental Validation of the Topotactic Transformation of MgAl Layered Double Hydroxides.

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Zhang, Shi-Tong; Dou, Yibo; Zhou, Junyao; Pu, Min; Yan, Hong; Wei, Min; Evans, David G; Duan, Xue

2016-09-05

The thermal topotactic transformation mechanism of MgAl layered double hydroxides (LDHs) is investigated by a combined theoretical and experimental study. Thermogravimetric differential thermal analysis (TG-DTA) results reveal that the LDH phase undergoes four key endothermic events at 230, 330, 450, and 800 °C. DFT calculations show that the LDH decomposes into CO2 and residual O atoms via a monodentate intermediate at 330 °C. At 450 °C, the metal cations almost maintain their original distribution within the LDH(001) facet during the thermal dehydration process, but migrate substantially along the c-axis direction perpendicular to the (001) facet; this indicates that the metal arrangement/dispersion in the LDH matrix is maintained two-dimensionally. A complete collapse of the layered structure occurs at 800 °C, which results in a totally disordered cation distribution and many holes in the final product. The structures of the simulated intermediates are highly consistent with the observed in situ powder XRD data for the MgAl LDH sample calcined at the corresponding temperatures. Understanding the structural topotactic transformation process of LDHs would provide helpful information for the design and preparation of metal/metal oxides functional materials derived from LDH precursors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

RELATION BETWEEN PREECLAMPSIA AND CARDIAC ENZYMES

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Rubina Aziz

2010-12-01

Full Text Available Abstract    INTRODUCTION: Preeclampsia affects about 5-10% of all pregnancies and is a major cause of maternal, fetal and neonatal mortality and morbidity. The cardiovascular system undergoes a host of changes in association with development of preeclampsia. LDH is a useful biochemical marker that reflects the severity of the occurrence of preeclampsia.    METHOD AND MATERIALS: One hundred pregnant women were selected for this study, 50 normal pregnant women as controls and 50 preeclamptic women as the study group.  Cardiac enzymes (serum LDH, serum AST, serum CK and serum CKMB of these women were analyzed.    RESULTS: Mean Serum LDH and mean serum AST concentrations were significantly higher in preeclamptic patients compared to normal pregnant women (348.34 ± 59.17 vs. 255.92 ± 43.26, P < 0.01 and (34.32 ± 10.37 vs. 22.06 ± 5.10, P < 0.01 respectively.     CONCLUSION: LDH and AST may be increased due to liver damage. This endothelial vascular damage is the main cause in the occurrence of preeclampsia. Higher levels of LDH and AST are very useful markers to identify the occurrence of preeclampsia.      Keywords: LDH, Preeclampsia, AST, Cardiac Enzymes.

Reversible intercalation of ammonia molecules into a layered double hydroxide structure without exchanging nitrate counter-ions

International Nuclear Information System (INIS)

Carbajal Arizaga, Gregorio Guadalupe; Wypych, Fernando; Castillon Barraza, Felipe; Contreras Lopez, Oscar Edel

2010-01-01

A zinc/aluminum LDH was precipitated with recycled ammonia from a chemical vapor deposition reaction. The LDH presented a crystalline phase with basal distance of 8.9 A, typical for nitrate-containing LDHs, and another phase with a basal distance of 13.9 A. Thermal treatment at 150 o C eliminated the phase with the bigger basal distance leaving only the anhydrous nitrate-intercalated LDH structure with 8.9 A. Intense N-H stretching modes in the FTIR spectra suggested that the expansion was due to intercalation of ammonia in the form of [NH 4 (NH 3 ) n ] + species. When additional samples were precipitated with pure ammonia, the conventional LDH nitrate structure was obtained (8.9 A basal distance) at pH=7, as well as a pure crystalline phase with 13.9 A basal distance at pH=10 due to ammonia intercalation that can be removed by heating at 150 o C or by stirring in acetone, confirming a unusual sensu stricto intercalation process into a LDH without exchanging nitrate ions. - Graphical abstract: LDH-nitrate precipitated with ammonia expands the interlayer space if ammonia is bubbled up to pH 10. The basal distance decreased when the compound was heated at 150 o C or stirred in acetone. Nitrate ions are not exchanged.

The influence of the UV irradiation intensity on photocatalytic activity of ZnAl layered double hydroxides and derived mixed oxides

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Hadnađev-Kostić Milica S.

2012-01-01

Full Text Available Layered double hydroxides (LDHs have been studied to a great extent as environmental-friendly complex materials that can be used as photocatalysts or photocatalyst supports. ZnAl layered double hydroxides and their derived mixed oxides were chosen for the investigation of photocatalytic performances in correlation with the UV intensities measured in the South Pannonia region. Low supersaturation coprecipitation method was used for the ZnAl LDH synthesis. For the characterization of LDH and thermal treated samples powder X-ray diffraction (XRD, scanning electron microscopy (SEM, electron dispersive spectroscopy (EDS, nitrogen adsorption-desorption were used. The decomposition of azodye, methylene blue was chosen as photocatalytic test reaction. The study showed that the ZnAl mixed oxide obtained by thermal decomposition of ZnAl LDH has stable activity in the broader UV light irradiation range characterizing the selected region. Photocatalytic activity could be mainly attributed to the ZnO phase, detected both in LDH and thermally treated samples. The study showed that the ZnAl mixed oxide obtained by the calcination of ZnAl LDH has a stable activity within the measured UV light irradiation range; whereas the parent ZnAl LDH catalyst did not perform satisfactory when low UV irradiation intensity is implied.

Prognostic significance of serum lactate dehydrogenase levels in Ewing's sarcoma: A meta-analysis.

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Li, Suoyuan; Yang, Qing; Wang, Hongsheng; Wang, Zhuoying; Zuo, Dongqing; Cai, Zhengdong; Hua, Yingqi

2016-12-01

A number of studies have investigated the role of serum lactate dehydrogenase (LDH) levels in patients with Ewing's sarcoma, although these have yielded inconsistent and inconclusive results. Therefore, the present study aimed to systematically review the published studies and conduct a meta-analysis to assess its prognostic value more precisely. Cohort studies assessing the prognostic role of LDH levels in patients with Ewing's sarcoma were included. A pooled hazard ratio (HR) with 95% confidence intervals (CIs) of overall survival (OS) or 5-year disease-free survival (DFS) was used to assess the prognostic role of the levels of serum LDH. Nine studies published between 1980 and 2014, with a total of 1,412 patients with Ewing's sarcoma, were included. Six studies, with a total of 644 patients, used OS as the primary endpoint and four studies, with 795 patients, used 5-year DFS. Overall, the pooled HR evaluating high LDH levels was 2.90 (95% CI: 2.09-4.04) for OS and 2.40 (95% CI: 1.93-2.98) for 5-year DFS. This meta-analysis demonstrates that high levels of serum LDH are associated with lower OS and 5-year DFS rates in patients with Ewing's sarcoma. Therefore, serum LDH levels are an effective biomarker of Ewing's sarcoma prognosis.

Misconceptions regarding basic thermodynamics and enzyme kinetics have led to erroneous conclusions regarding the metabolic importance of lactate dehydrogenase isoenzyme expression.

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Bak, Lasse K; Schousboe, Arne

2017-11-01

Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate involving the coenzyme NAD + . Part of the foundation for the proposed shuttling of lactate from astrocytes to neurons during brain activation is the differential distribution of LDH isoenzymes between the two cell types. In this short review, we outline the basic kinetic properties of the LDH isoenzymes expressed in neurons and astrocytes, and argue that the distribution of LDH isoenzymes does not in any way govern directional flow of lactate between the two cellular compartments. The two main points are as follows. First, in line with the general concept of chemical catalysis, enzymes do not influence the thermodynamic equilibrium of a chemical reaction but merely the speed at which equilibrium is obtained. Thus, differential distribution of LDH isoenzymes with different kinetic parameters does not predict which cells are producing and which are consuming lactate. Second, the thermodynamic equilibrium of the reaction is toward the reduced substrate (i.e., lactate), which is reflected in the concentrations measured in brain tissue, suggesting that the reaction is at near-equilibrium at steady state. To conclude, the cellular distribution of LDH isoenzymes is of little if any consequence in determining any directional flow of lactate between neurons and astrocytes. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Migration of nanosized layered double hydroxide platelets from polylactide nanocomposite films.

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Schmidt, B; Katiyar, V; Plackett, D; Larsen, E H; Gerds, N; Koch, C Bender; Petersen, J H

2011-01-01

Melt-extruded L-polylactide (PLA) nanocomposite films were prepared from commercially available PLA and laurate-modified Mg-Al layered double hydroxide (LDH-C12). Three films were tested for total migration as well as specific migration of LDH, tin, laurate and low molecular weight PLA oligomers (OLLA). This is the first reported investigation on the migration properties of PLA-LDH nanocomposite films. The tests were carried out as part of an overall assessment of the suitability of such films for use as food contact materials (FCM). Total migration was determined according to a European standard method. All three films showed migration of nanosized LDH, which was quantified using acid digestion followed by inductively coupled plasma mass spectrometric (ICP-MS) detection of (26)Mg. Migration of LDH from the films was also confirmed by examining migrates using transmission electron microscopy (TEM) and was attributed indirectly to the significant PLA molecular weight reduction observed in extruded PLA-LDH-C12 films. Migration of tin was detected in two of the film samples prepared by dispersion of LDH-C12 using a masterbatch technique and migration of the laurate organomodifier took place from all three film types. The results indicate that the material properties are in compliance with the migration limits for total migration and specific lauric acid migration as set down by the EU legislation for FCM, at least if a reduction factor for fresh meat is taken into consideration. The tin detected arises from the use of organotin catalysts in the manufacture of PLA.

Lactate dehydrogenase activity is inhibited by methylmalonate in vitro.

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Saad, Laura O; Mirandola, Sandra R; Maciel, Evelise N; Castilho, Roger F

2006-04-01

Methylmalonic acidemia (MMAemia) is an inherited metabolic disorder of branched amino acid and odd-chain fatty acid metabolism, involving a defect in the conversion of methylmalonyl-coenzyme A to succinyl-coenzyme A. Systemic and neurological manifestations in this disease are thought to be associated with the accumulation of methylmalonate (MMA) in tissues and biological fluids with consequent impairment of energy metabolism and oxidative stress. In the present work we studied the effect of MMA and two other inhibitors of mitochondrial respiratory chain complex II (malonate and 3-nitropropionate) on the activity of lactate dehydrogenase (LDH) in tissue homogenates from adult rats. MMA potently inhibited LDH-catalyzed conversion of lactate to pyruvate in liver and brain homogenates as well as in a purified bovine heart LDH preparation. LDH was about one order of magnitude less sensitive to inhibition by MMA when catalyzing the conversion of pyruvate to lactate. Kinetic studies on the inhibition of brain LDH indicated that MMA inhibits this enzyme competitively with lactate as a substrate (K (i)=3.02+/-0.59 mM). Malonate and 3-nitropropionate also strongly inhibited LDH-catalyzed conversion of lactate to pyruvate in brain homogenates, while no inhibition was observed by succinate or propionate, when present in concentrations of up to 25 mM. We propose that inhibition of the lactate/pyruvate conversion by MMA contributes to lactate accumulation in blood, metabolic acidemia and inhibition of gluconeogenesis observed in patients with MMAemia. Moreover, the inhibition of LDH in the central nervous system may also impair the lactate shuttle between astrocytes and neurons, compromising neuronal energy metabolism.

Lactate dehydrogenase of Mugil sp. (Mugilidae, Perciformes. Lack of electrokinetic, thermostability and kinetic differences among individuals with different number of scales

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Marcelo dos Santos

2000-03-01

Full Text Available The scale number in lateral sets (SNS of Mugil sp. (Mugilidae, Perciformes collected in the lagoon-estuarine region of Cananéia, State of São Paulo ranges from 33 to 39. Electrokinetic, kinetic and thermostability properties of lactate dehydrogenase (LDH were tested to determine if individuals with different SNS correspond to different species or populations of mullet. As in many other teleosts, LDH-A*, LDH-B*, and LDH-C* loci were detected. Through a two-fold serial dilution method applied to 10 different tissues of Mugil sp., a bidirectionally divergent expression of these loci was suggested. No association among LDH electrophoretic pattern, thermal inactivation, kinetic responses and different SNS was observed. The apparent Km (pyr values obtained here were similar to Km values obtained by other authors for muscle and heart LDH or their purified isoforms. The effect of NaCl on Km and Vmax values of Mugil sp. (35 and 39 SNS individuals indicates that this salt behaves as a competitive inhibitor, since it decreases enzyme-substrate affinity. Thus, electrokinetic and thermostability behavior, Km and Vmax values and the effect of NaCl do not permit us to consider these mullets, with SNS ranging from 33 to 39, as belonging to different populations or species.O número de escamas em séries laterais (SNS de exemplares de Mugil sp. (Mugilidae, Perciformes coletados na região estuarino-lagunar de Cananéia, Estado de São Paulo, varia de 33 a 39. A fim de tentar determinar se exemplares com diferentes SNS corresponderiam a diferentes espécies ou populações de tainhas, foram analisadas as propriedades eletrocinéticas, cinéticas e de termoestabilidade da sua lactato desidrogenase (LDH. A exemplo de muitos teleósteos, a LDH de Mugil sp. mostrou-se codificada por 3 locos gênicos: LDH-A*, LDH-B* e LDH-C*. Método de diluições seriadas aplicado a 10 diferentes tecidos dessa espécie sugeriu um padrão bidirecionalmente divergente de express

the tnfluence of breed, castration and age on muscle fibre type and ...

African Journals Online (AJOL)

For histochemical demonstration of succinic de- hydrogenase situated in the ..... centage coefficient of variation elucidates the matter. At. 34/' in the case of the .... metabolic and functional properties of skeletal muscle in relation to meat quality,.

Metabolic engineering of mannitol production in Lactococcus lactis: influence of overexpression of mannitol 1-phosphate dehydrogenase in different genetic backgrounds.

Science.gov (United States)

Wisselink, H Wouter; Mars, Astrid E; van der Meer, Pieter; Eggink, Gerrit; Hugenholtz, Jeroen

2004-07-01

To obtain a mannitol-producing Lactococcus lactis strain, the mannitol 1-phosphate dehydrogenase gene (mtlD) from Lactobacillus plantarum was overexpressed in a wild-type strain, a lactate dehydrogenase(LDH)-deficient strain, and a strain with reduced phosphofructokinase activity. High-performance liquid chromatography and (13)C nuclear magnetic resonance analysis revealed that small amounts (<1%) of mannitol were formed by growing cells of mtlD-overexpressing LDH-deficient and phosphofructokinase-reduced strains, whereas resting cells of the LDH-deficient transformant converted 25% of glucose into mannitol. Moreover, the formed mannitol was not reutilized upon glucose depletion. Of the metabolic-engineering strategies investigated in this work, mtlD-overexpressing LDH-deficient L. lactis seemed to be the most promising strain for mannitol production.

Rational design of Mg-Al mixed oxide-supported bimetallic catalysts for dry reforming of methane

Energy Technology Data Exchange (ETDEWEB)

Tsyganok, Andrey I. [Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, D' Iorio Hall, 10 Marie Curie Street, Ottawa, Ont. (Canada); Inaba, Mieko [Natural Gas Technology Development Team, Teikoku Oil Co., 9-23-30 Kitakarasuyama, Setagaya-ku, Tokyo 157-0061 (Japan); Tsunoda, Tatsuo; Uchida, Kunio; Suzuki, Kunio; Hayakawa, Takashi [Institute for Materials and Chemical Process, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565 (Japan); Takehira, Katsuomi [Department of Applied Chemistry, Faculty of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan)

2005-09-18

A novel synthetic strategy for preparing bimetallic Ru-M (M=Cr, Fe, Co, Ni and Cu) catalysts, supported on Mg-Al mixed oxide, has been introduced. It was based on a 'memory effect', i.e. on the ability of Mg-Al mixed oxide to reconstruct a layered structure upon rehydration with an aqueous solution. By repeated calcinations-rehydration cycles, layered double hydroxide (LDH) precursors of catalysts containing two different metals were synthesized. Bimetallic catalysts were then generated (1) in situ from LDH under methane reforming reaction conditions and (2) from mixed metal oxides obtained by preliminary LDH calcination. Among all the LDH-derived catalysts, a Ru{sup 0.1%}-Ni{sup 5.0%}/MgAlO{sub x} sample revealed the highest activity and selectivity to syngas, a suitable durability and a low coking capacity. A promoting effect of ruthenium on catalytic function of supported nickel was demonstrated. Preliminary LDH calcination was shown to markedly affect the catalytic activity of the derived catalysts and especially their coking properties.

Controlled supramolecular structure of guanosine monophosphate in the interlayer space of layered double hydroxide

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Gyeong-Hyeon Gwak

2016-12-01

Full Text Available Guanosine monophosphates (GMPs were intercalated into the interlayer space of layered double hydroxides (LDHs and the molecular arrangement of GMP was controlled in LDHs. The intercalation conditions such as GMP/LDH molar ratio and reaction temperature were systematically adjusted. When the GMP/LDH molar ratio was 1:2, which corresponds to the charge balance between positive LDH sheets and GMP anions, GMP molecules were well-intercalated to LDH. At high temperature (100 and 80 °C, a single GMP molecule existed separately in the LDH interlayer. On the other hand, at lower temperature (20, 40 and 60 °C, GMPs tended to form ribbon-type supramolecular assemblies. Differential scanning calorimetry showed that the ribbon-type GMP assembly had an intermolecular interaction energy of ≈101 kJ/mol, which corresponds to a double hydrogen bond between guanosine molecules. Once stabilized, the interlayer GMP orientations, single molecular and ribbon phase, were successfully converted to the other phase by adjusting the external environment by stoichiometry or temperature control.

Layered double hydroxide-like materials: nanocomposites for use in concrete

International Nuclear Information System (INIS)

Raki, L.; Beaudoin, J.J.; Mitchell, L.

2004-01-01

Nitrobenzoic acid (NBA), naphthalene-2, 6-disulfonic acid (26NS), and naphthalene-2 sulfonic acid (2NS) salts were intercalated into a layered double hydroxide-like host material (LDH). The intercalation process was achieved by anion exchange of nitrates in the host material, Ca 2 Al(OH) 6 NO 3 , nH 2 O (CaAl LDH), which was prepared by a coprecipitation technique. The resulting organo derivatives CaAlNBA LDH, CaAl26NS LDH, and CaAl2NS LDH produced a tilted orientation of NBA and 26NS anions in the interlayer space, while 2NS anions induced a perpendicular bilayer arrangement. Materials characterization was carried out using X-ray diffraction (XRD), IR-spectroscopy, thermal analysis, and scanning electron microscopy (SEM). These preliminary results open up a new direction towards the synthesis of nanocomposites using polymeric entities and layered materials for future applications in cement and concrete science, e.g., control of the effect of admixtures on the kinetics of cement hydration by programming their temporal release

Intercalation and structural aspects of macroRAFT agents into MgAl layered double hydroxides

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Dessislava Kostadinova

2016-12-01

Full Text Available Increasing attention has been devoted to the design of layered double hydroxide (LDH-based hybrid materials. In this work, we demonstrate the intercalation by anion exchange process of poly(acrylic acid (PAA and three different hydrophilic random copolymers of acrylic acid (AA and n-butyl acrylate (BA with molar masses ranging from 2000 to 4200 g mol−1 synthesized by reversible addition-fragmentation chain transfer (RAFT polymerization, into LDH containing magnesium(II and aluminium(III intralayer cations and nitrates as counterions (MgAl-NO3 LDH. At basic pH, the copolymer chains (macroRAFT agents carry negative charges which allowed the establishment of electrostatic interactions with the LDH interlayer and their intercalation. The resulting hybrid macroRAFT/LDH materials displayed an expanded interlamellar domain compared to pristine MgAl-NO3 LDH from 1.36 nm to 2.33 nm. Depending on the nature of the units involved into the macroRAFT copolymer (only AA or AA and BA, the intercalation led to monolayer or bilayer arrangements within the interlayer space. The macroRAFT intercalation and the molecular structure of the hybrid phases were further characterized by Fourier transform infrared (FTIR and solid-state 13C, 1H and 27Al nuclear magnetic resonance (NMR spectroscopies to get a better description of the local structure.

Performance of Rapid Diagnostic Tests for Imported Malaria in Clinical Practice: Results of a National Multicenter Study

Science.gov (United States)

Houzé, Sandrine; Boutron, Isabelle; Marmorat, Anne; Dalichampt, Marie; Choquet, Christophe; Poilane, Isabelle; Godineau, Nadine; Le Guern, Anne-Sophie; Thellier, Marc; Broutier, Hélène; Fenneteau, Odile; Millet, Pascal; Dulucq, Stéphanie; Hubert, Véronique; Houzé, Pascal; Tubach, Florence; Le Bras, Jacques; Matheron, Sophie

2013-01-01

We compared the performance of four rapid diagnostic tests (RDTs) for imported malaria, and particularly Plasmodium falciparum infection, using thick and thin blood smears as the gold standard. All the tests are designed to detect at least one protein specific to P. falciparum ( Plasmodium histidine-rich protein 2 (PfHRP2) or Plasmodium LDH (PfLDH)) and one pan-Plasmodium protein (aldolase or Plasmodium LDH (pLDH)). 1,311 consecutive patients presenting to 9 French hospitals with suspected malaria were included in this prospective study between April 2006 and September 2008. Blood smears revealed malaria parasites in 374 cases (29%). For the diagnosis of P. falciparum infection, the three tests detecting PfHRP2 showed high and similar sensitivity (96%), positive predictive value (PPV) (90%) and negative predictive value (NPV) (98%). The PfLDH test showed lower sensitivity (83%) and NPV (80%), despite good PPV (98%). For the diagnosis of non-falciparum species, the PPV and NPV of tests targeting pLDH or aldolase were 94–99% and 52–64%, respectively. PfHRP2-based RDTs are thus an acceptable alternative to routine microscopy for diagnosing P. falciparum malaria. However, as malaria may be misdiagnosed with RDTs, all negative results must be confirmed by the reference diagnostic method when clinical, biological or other factors are highly suggestive of malaria. PMID:24098699

Electrosynthesized Ni-Al Layered Double Hydroxide-Pt Nanoparticles as an Inorganic Nanocomposite and Potentate Anodic Material for Methanol Electrooxidation in Alkaline Media

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Biuck Habibi

2017-04-01

Full Text Available In this study, Ni-Al layered double hydroxide (LDH-Pt nanoparticles (PtNPs as an inorganic nano-composite was electrosynthesized on the glassy carbon electrode (GCE by a facile and fast two-step electrochemical process. Structure and physicochemical properties of PtNPs/Ni-Al LDH/GCE were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry and electrochemical methods. Then, electrocatalytic and stability characterizations of the PtNPs/Ni-Al LDH/GCE for methanol oxidation in alkaline media were investigated in detail by cyclic voltammetry, chronoamperometry, and chronopotentiometry measurements. PtNPs/Ni-Al LDH/GCE exhibited higher electrocatalytic activity than PtNPs/GCE and Ni-Al LDH/GCE. Also, the resulted chronoam-perograms indicated that the PtNPs/Ni-Al LDH/GCE has a better stability. Copyright © 2017 BCREC GROUP. All rights reserved Received: 30th March 2016; Revised: 29th July 2016; Accepted: 9th September 2016 How to Cite: Habibi, B., Ghaderi, S. (2017. Electro Synthesized Ni-Al Layered Double Hydroxide-Pt Nanoparticles as an Inorganic Nanocomposite and Potentate Anodic Material for Methanol Electro-Oxidation in Alkaline Media. Bulletin of Chemical Reaction Engineering & Catalysis, 12(1: 1-13 (doi:10.9767/bcrec.12.1.460.1-13 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.1.460.1-13

Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

Science.gov (United States)

Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

2017-01-01

Al(OH)3 and Ca(OH)2 powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. Ca-Al precursor (C3A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO4 LDH product. Ca-Al-CrO4 LDH phase occurred preferentially to Ca-Al-MCl2 LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist.

Stacking Faults and Polytypes for Layered Double Hydroxides: What Can We Learn from Simulated and Experimental X-ray Powder Diffraction Data?

Science.gov (United States)

Sławiński, Wojciech A; Sjåstad, Anja Olafsen; Fjellvåg, Helmer

2016-12-19

Layered double hydroxides (LDH) are a broad group of widely studied materials. The layered character of those materials and their high flexibility for accommodating different metals and anions make them technologically interesting. The general formula for the LDH compound is [M 1-x II M x III (OH) 2 ][A n- ] x/n ·mH 2 O, where M II is a divalent metal cation which can be substituted by M III trivalent cation, and A n- is a charge compensating anion located between positively charged layers. In this paper we present a comprehensive study on possible structural disorder in LDH. We show how X-ray powder diffraction (XRPD) can be used to reveal important features of the LDH crystal structure such as stacking faults, random interlayer shifts, anion-molecule orientation, crystal water content, distribution of interlayer distances, and also LDH slab thickness. All calculations were performed using the Discus package, which gives a better flexibility in defining stacking fault sequences, simulating and refining XRPD patterns, relative to DIFFaX, DIFFaX+, and FAULTS. Finally, we show how the modeling can be applied to two LDH samples: Ni 0.67 Cr 0.33 (OH) 2 (CO 3 ) 0.16 ·mH 2 O (3D structure) and Mg 0.67 Al 0.33 (OH) 2 (NO 3 ) 0.33 (2D layered structure).

Development of L-lactate dehydrogenase biosensor based on porous silicon resonant microcavities as fluorescence enhancers.

Science.gov (United States)

Jenie, S N Aisyiyah; Prieto-Simon, Beatriz; Voelcker, Nicolas H

2015-12-15

The up-regulation of L-lactate dehydrogenase (LDH), an intracellular enzyme present in most of all body tissues, is indicative of several pathological conditions and cellular death. Herein, we demonstrate LDH detection using porous silicon (pSi) microcavities as a luminescence-enhancing optical biosensing platform. Non-fluorescent resazurin was covalently attached onto the pSi surface via thermal hydrocarbonisation, thermal hydrosylilation and acylation. Each surface modification step was confirmed by means of FTIR and the optical shifts of the resonance wavelength of the microcavity. Thermal hydrocarbonisation also afforded excellent surface stability, ensuring that the resazurin was not reduced on the pSi surface. Using a pSi microcavity biosensor, the fluorescence signal upon detection of LDH was amplified by 10 and 5-fold compared to that of a single layer and a detuned microcavity, respectively, giving a limit of detection of 0.08 U/ml. The biosensor showed a linear response between 0.16 and 6.5 U/ml, covering the concentration range of LDH in normal as well as damaged tissues. The biosensor was selective for LDH and did not produce a signal upon incubation with another NAD-dependant enzyme L-glutamic dehydrogenase. The use of the pSi microcavity as a sensing platform reduced reagent usage by 30% and analysis time threefold compared to the standard LDH assay in solution. Copyright © 2015 Elsevier B.V. All rights reserved.

CalA, a Cyanobacterial AbrB Protein, Interacts with the Upstream Region of hypC and Acts as a Repressor of Its Transcription in the Cyanobacterium Nostoc sp. Strain PCC 7120▿ †

Science.gov (United States)

Agervald, Åsa; Zhang, Xiaohui; Stensjö, Karin; Devine, Ellenor; Lindblad, Peter

2010-01-01

The filamentous, heterocystous, nitrogen-fixing cyanobacterium Nostoc sp. strain PCC 7120 may contain, depending on growth conditions, up to two hydrogenases directly involved in hydrogen metabolism. HypC is one out of at least seven auxiliary gene products required for synthesis of a functional hydrogenase, specifically involved in the maturation of the large subunit. In this study we present a protein, CalA (Alr0946 in the genome), belonging to the transcription regulator family AbrB, which in protein-DNA assays was found to interact with the upstream region of hypC. Transcriptional investigations showed that calA is cotranscribed with the downstream gene alr0947, which encodes a putative protease from the abortive infection superfamily, Abi. CalA was shown to interact specifically not only with the upstream region of hypC but also with its own upstream region, acting as a repressor on hypC. The bidirectional hydrogenase activity was significantly downregulated when CalA was overexpressed, demonstrating a correlation with the transcription factor, either direct or indirect. In silico studies showed that homologues to both CalA and Alr0947 are highly conserved proteins within cyanobacteria with very similar physical organizations of the corresponding structural genes. Possible functions of the cotranscribed downstream protein Alr0947 are presented. In addition, we present a three-dimensional (3D) model of the DNA binding domain of CalA and putative DNA binding mechanisms are discussed. PMID:20023111

Small-angle X-ray scattering studies on the X-ray induced aggregation of ribonnuclease, lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase and serum albumin. A comparison with malate synthase

International Nuclear Information System (INIS)

Zipper, P.; Gatterer, H.G.; Schutz, J.; Durchschlag, H.

1980-01-01

The X-ray induced aggregation of ribonuclease, lactate dehydrogenase (LDH), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and serum albumin in aqueous solution was monitored in situ by means of small-angle X-ray scattering. Measurements carried out with ribonuclease, LDH and serum albumin in the absence of dithiothreitol (DTT) and with GAPDH in the presence of 0.2mM DTT established the following series for the rates of aggregation of the proteins under these conditions: ribonuclease >LDH> >GAPDH> serum albumin. Within six hours from the beginning of irradiation (i.e. about the time required for the exposure of one complete scattering curve under the conditions of our experiments) the following increases of R tilde resulted: ribonuclease 9%, LDH 7%, GAPDH 4%, serum albumin <1%. Changes of R tilde exceeding 1% are, of course, too high to be tolerated in conventional scattering experiments. Measurements carried out with LDH and GAPDH in the presence of 2mM DTT established a strong protective effect of DTT against the X-ray induced aggregation of these enzymes. The initial increase of R tilde upon irradiation of LDH and GAPDH in the presence of 2mM DTT was found to be even lower than the increase of R tilde observed when serum albumin was irradiated in the absence of DTT. However, the observed decrease of anti x of LDH and GAPDH at the early stages of irradiation suggested the occurrence of fragmentation of the enzymes as another consequence of radiation damage. This finding is discussed in context with the results from previous scattering experiments and electrophoretic studies on malate synthase. (author)

The photoluminescence of Co-Al-layered double hydroxide

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

We report a new optical behaviour of pure Co-Al-layered double hydroxide (LDH). It was found that the Co-Al-LDH sample could emit fluorescence without any fluorescent substances intercalated. Its excitation spectrum shows a maximum peak near the wavelength 370 nm, the maximum emission peak appears at 430 nm and the photoluminescence colour of the Co-Al-LDH sample is blue. This new optical property will be expected to extend the potential applications of LDHs in optical materials field.

Influence of sodium dodecyl sulfate concentration on the photocatalytic activity and dielectric properties of intercalated sodium dodecyl sulfate into Zn–Cd–Al layered double hydroxide

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Abdullah Ahmed Ali, E-mail: abdullah2803@gmail.com [Department of Physics, Faculty of Applied Science, Thamar University, Dhamar 87246 (Yemen); Talib, Zainal Abidin [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, Serdang, Selangor 43400 (Malaysia); Hussein, Mohd Zobir [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, UPM, Serdang, Selangor 43400 (Malaysia)

2015-02-15

Highlights: • Zn–Cd–Al–LDH–DS were synthesized with different SDS concentrations. • Photocatalytic activity of samples was improved by increasing SDS concentration. • Dielectric response of LDH can be described by anomalous low frequency dispersion. • The dc conductivity values were calculated for Zn–Cd–Al–LDH–DS samples. • ESR spectra exhibited the successful intercalation of DS molecule into LDH gallery. - Abstract: Sodium dodecyl sulfate (SDS) has been successfully intercalated into Zn–Cd–Al–LDH precursor with different SDS concentrations (0.2, 0.3, 0.4, 0.5 and 1 mol L{sup −1}) using the coprecipitation method at (Zn{sup 2+} + Cd{sup 2+})/Al{sup 3+} molar ratio of 13 and pH 8. The structural, morphological, texture and composition properties of the synthesized (Zn–Cd–Al–LDH–DS) nanostructure were investigated using powder X-ray diffraction (PXRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR), respectively. The photocatalytic activity of these materials was developed by increasing the concentration of intercalated SDS. The absorbance spectra have been used to detect an anion in the LDH interlayer before and after the intercalation process, which confirmed the presence of the dodecyl sulfate (DS{sup −}) anion into LDH gallery after intercalation. The anomalous low frequency dispersion (ALFD) has been used to describe the dielectric response of Zn–Cd–Al–LDH–DS nanostructure using the second type of universal power law. At low frequency, the polarization effect of electrodes caused the rising in dielectric constant and loss values. An important result of the dielectric measurements is the calculated dc conductivity values, which are new in dielectric spectroscopy of LDH materials. An important result of the electron spin resonance (ESR) spectra exhibited the successful intercalation of DS molecule into LDH gallery. The g-factor value was affected by

Efficient uranium capture by polysulfide/layered double hydroxide composites.

Science.gov (United States)

Ma, Shulan; Huang, Lu; Ma, Lijiao; Shim, Yurina; Islam, Saiful M; Wang, Pengli; Zhao, Li-Dong; Wang, Shichao; Sun, Genban; Yang, Xiaojing; Kanatzidis, Mercouri G

2015-03-18

There is a need to develop highly selective and efficient materials for capturing uranium (normally as UO2(2+)) from nuclear waste and from seawater. We demonstrate the promising adsorption performance of S(x)-LDH composites (LDH is Mg/Al layered double hydroxide, [S(x)](2-) is polysulfide with x = 2, 4) for uranyl ions from a variety of aqueous solutions including seawater. We report high removal capacities (q(m) = 330 mg/g), large K(d)(U) values (10(4)-10(6) mL/g at 1-300 ppm U concentration), and high % removals (>95% at 1-100 ppm, or ∼80% for ppb level seawater) for UO2(2+) species. The S(x)-LDHs are exceptionally efficient for selectively and rapidly capturing UO2(2+) both at high (ppm) and trace (ppb) quantities from the U-containing water including seawater. The maximum adsorption coeffcient value K(d)(U) of 3.4 × 10(6) mL/g (using a V/m ratio of 1000 mL/g) observed is among the highest reported for U adsorbents. In the presence of very high concentrations of competitive ions such as Ca(2+)/Na(+), S(x)-LDH exhibits superior selectivity for UO2(2+), over previously reported sorbents. Under low U concentrations, (S4)(2-) coordinates to UO2(2+) forming anionic complexes retaining in the LDH gallery. At high U concentrations, (S4)(2-) binds to UO2(2+) to generate neutral UO2S4 salts outside the gallery, with NO3(-) entering the interlayer to form NO3-LDH. In the presence of high Cl(-) concentration, Cl(-) preferentially replaces [S4](2-) and intercalates into LDH. Detailed comparison of U removal efficiency of S(x)-LDH with various known sorbents is reported. The excellent uranium adsorption ability along with the environmentally safe, low-cost constituents points to the high potential of S(x)-LDH materials for selective uranium capture.

Evaluation of the Palutop+4 malaria rapid diagnostic test in a non-endemic setting

Directory of Open Access Journals (Sweden)

van Esbroeck Marjan

2009-12-01

Full Text Available Abstract Background Palutop+4 (All. Diag, Strasbourg, France, a four-band malaria rapid diagnostic test (malaria RDT targeting the histidine-rich protein 2 (HRP-2, Plasmodium vivax-specific parasite lactate dehydrogenase (Pv-pLDH and pan Plasmodium-specific pLDH (pan-pLDH was evaluated in a non-endemic setting on stored whole blood samples from international travellers suspected of malaria. Methods Microscopy corrected by PCR was the reference method. Samples include those infected by Plasmodium falciparum (n = 323, Plasmodium vivax (n = 97, Plasmodium ovale (n = 73 and Plasmodium malariae (n = 25 and 95 malaria negative samples. Results The sensitivities for the diagnosis of P. falciparum, P. vivax, P. malariae and P. ovale were 85.1%, 66.0%, 32.0% and 5.5%. Sensitivities increased at higher parasite densities and reached 90.0% for P. falciparum >100/μl and 83.8% for P. vivax > 500/μl. Fourteen P. falciparum samples reacted with the Pv-pLDH line, one P. vivax sample with the HRP-2 line, and respectively two and four P. ovale and P. malariae samples reacted with the HRP-2 line. Two negative samples gave a signal with the HRP-2 line. Faint and weak line intensities were observed for 129/289 (44.6% HRP-2 lines in P. falciparum samples, for 50/64 (78.1% Pv-pLDH lines in P. vivax samples and for 9/13 (69.2% pan-pLDH lines in P. ovale and P. malariae samples combined. Inter-observer reliabilities for positive and negative readings were excellent for the HRP-2 and Pv-pLDH lines (overall agreement > 92.0% and kappa-values for each pair of readers ≥ 0.88, and good for the pan-pLDH line (85.5% overall agreement and kappa-values ≥ 0.74. Conclusions Palutop+4 performed moderately for the detection of P. falciparum and P. vivax, but sensitivities were lower than those of three-band malaria RDTs.

Sequence Classification: 258180 [

Lifescience Database Archive (English)

Full Text Available Non-TMB Non-TMH Non-TMB Non-TMB Non-TMB Non-TMB >gi|71909593|ref|YP_287180.1| HupH hydrogenase express...ion protein, C-terminal conserved region || http://www.ncbi.nlm.nih.gov/protein/71909593 ...

Hydrogen utilization potential in subsurface sediments

DEFF Research Database (Denmark)

Adhikari, Rishi Ram; Glombitza, Clemens; Nickel, Julia

2016-01-01

Pacific, and Gulf of Mexico) with different predominant electron-acceptors. Hydrogenases constitute a diverse family of enzymes expressed by microorganisms that utilize molecular hydrogen as a metabolic substrate, product, or intermediate. The assay reveals the potential for utilizing molecular hydrogen...

A Simple Approach for the Synthesis of Gold Nanoparticles Mediated by Layered Double Hydroxide

OpenAIRE

Silva, Aires da Conceição; de Souza, Andréa Luzia Ferreira; Simão, Renata Antoun; Brum Malta, Luiz Fernando

2013-01-01

The present work introduces a new procedure to obtain gold nanoparticles (AuNPs). AuNPs (77–213 nm) were obtained in the absence of any classical reducing agents in a medium containing Mg2+/Al3+ layered double hydroxide (LDH) and N,N-dimethylformamide. XRD analysis showed the presence of crystalline phases of gold in the Au/LDH composite. The 2θ values of peaks corresponding to the LDH interlayer distance indicated that metallic NPs were deposited on the surface of the material. Furthermore, ...

Safety and outcome of treatment of metastatic melanoma using 3-bromopyruvate: a concise literature review and case study.

Science.gov (United States)

El Sayed, Salah Mohamed; Mohamed, Walaa Gamal; Seddik, Minnat-Allah Hassan; Ahmed, Al-Shimaa Ahmed; Mahmoud, Asmaa Gamal; Amer, Wael Hassan; Helmy Nabo, Manal Mohamed; Hamed, Ahmed Roshdi; Ahmed, Nagwa Sayed; Abd-Allah, Ali Abdel-Rahman

2014-07-01

3-Bromopyruvate (3BP) is a new, promising anticancer alkylating agent with several notable functions. In addition to inhibiting key glycolysis enzymes including hexokinase II and lactate dehydrogenase (LDH), 3BP also selectively inhibits mitochondrial oxidative phosphorylation, angiogenesis, and energy production in cancer cells. Moreover, 3BP induces hydrogen peroxide generation in cancer cells (oxidative stress effect) and competes with the LDH substrates pyruvate and lactate. There is only one published human clinical study showing that 3BP was effective in treating fibrolamellar hepatocellular carcinoma. LDH is a good measure for tumor evaluation and predicts the outcome of treatment better than the presence of a residual tumor mass. According to the Warburg effect, LDH is responsible for lactate synthesis, which facilitates cancer cell survival, progression, aggressiveness, metastasis, and angiogenesis. Lactate produced through LDH activity fuels aerobic cell populations inside tumors via metabolic symbiosis. In melanoma, the most deadly skin cancer, 3BP induced necrotic cell death in sensitive cells, whereas high glutathione (GSH) content made other melanoma cells resistant to 3BP. Concurrent use of a GSH depletor with 3BP killed resistant melanoma cells. Survival of melanoma patients was inversely associated with high serum LDH levels, which was reported to be highly predictive of melanoma treatment in randomized clinical trials. Here, we report a 28-year-old man presented with stage IV metastatic melanoma affecting the back, left pleura, and lung. The disease caused total destruction of the left lung and a high serum LDH level (4,283 U/L). After ethics committee approval and written patient consent, the patient received 3BP intravenous infusions (1-2.2 mg/kg), but the anticancer effect was minimal as indicated by a high serum LDH level. This may have been due to high tumor GSH content. On combining oral paracetamol, which depletes tumor GSH, with 3BP

Hepatitis C virus NS4B carboxy terminal domain is a membrane binding domain

Directory of Open Access Journals (Sweden)

Spaan Willy JM

2009-05-01

Full Text Available Abstract Background Hepatitis C virus (HCV induces membrane rearrangements during replication. All HCV proteins are associated to membranes, pointing out the importance of membranes for HCV. Non structural protein 4B (NS4B has been reported to induce cellular membrane alterations like the membranous web. Four transmembrane segments in the middle of the protein anchor NS4B to membranes. An amphipatic helix at the amino-terminus attaches to membranes as well. The carboxy-terminal domain (CTD of NS4B is highly conserved in Hepaciviruses, though its function remains unknown. Results A cytosolic localization is predicted for the NS4B-CTD. However, using membrane floatation assays and immunofluorescence, we now show targeting of the NS4B-CTD to membranes. Furthermore, a profile-profile search, with an HCV NS4B-CTD multiple sequence alignment, indicates sequence similarity to the membrane binding domain of prokaryotic D-lactate dehydrogenase (d-LDH. The crystal structure of E. coli d-LDH suggests that the region similar to NS4B-CTD is located in the membrane binding domain (MBD of d-LDH, implying analogy in membrane association. Targeting of d-LDH to membranes occurs via electrostatic interactions of positive residues on the outside of the protein with negative head groups of lipids. To verify that anchorage of d-LDH MBD and NS4B-CTD is analogous, NS4B-CTD mutants were designed to disrupt these electrostatic interactions. Membrane association was confirmed by swopping the membrane contacting helix of d-LDH with the corresponding domain of the 4B-CTD. Furthermore, the functionality of these residues was tested in the HCV replicon system. Conclusion Together these data show that NS4B-CTD is associated to membranes, similar to the prokaryotic d-LDH MBD, and is important for replication.

Adsorption of acid red from dye wastewater by Zn{sub 2}Al-NO{sub 3} LDHs and the resource of adsorbent sludge as nanofiller for polypropylene

Energy Technology Data Exchange (ETDEWEB)

Xue, Tianshan; Gao, Yanshan; Zhang, Zhang [College of Environmental Science and Engineering, Beijing Forestry University, 35 Qinghua East Road, Haidian District, Beijing 100083 (China); Umar, Ahmad, E-mail: ahmadumar786@gmail.com [Department of Chemistry, College of Science and Arts, Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Promising Centre for Sensors and Electronic Devices (PCSED), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Yan, Xingru; Zhang, Xi; Guo, Zhanhu [Integrated Composites Laboratory, Dan F Smith Department of Chemical Engineering, Lamar University, Beaumont, TX 77710 (United States); Wang, Qiang, E-mail: qiang.wang.ox@gmail.com [College of Environmental Science and Engineering, Beijing Forestry University, 35 Qinghua East Road, Haidian District, Beijing 100083 (China)

2014-02-25

Highlights: • High removal efficiency of acid red 97 from dye wastewater was achieved by using Zn{sub 2}Al-NO{sub 3} LDHs adsorbent. • The resource of the LDH adsorbent sludge as nanofiller for polypropylene (PP) was proposed for the first time. • The thermal stability of PP was significantly improved by introducing only small amount of LDH adsorbent sludge. • The resource the dye adsorbent sludge as multifunctional nanofiller for polymers is a very promising option. -- Abstract: In this contribution, we report the removal of acid red 97 (AC97) from simulated dye wastewater by using Zn{sub 2}Al-NO{sub 3} layered double hydroxides (LDHs) adsorbent, and the resource of the LDH adsorbent sludge as nanofiller for polypropylene (PP) for the first time. The obtained Zn{sub 2}Al-NO{sub 3} LDH was analyzed using X-ray diffraction and scanning electron microscopy analysis, confirming the formation of pure and platelike LDH nanoparticles. The effects of adsorption time and initial dye concentration on the removal of AC97 from wastewater were systematically investigated, showing that the Zn{sub 2}Al-NO{sub 3} LDHs is very efficient in removing AC97. The saturated adsorption capacity of water washed and acetone washed Zn{sub 2}Al-LDHs is 204.4 and 299.5 mg/g, respectively. Finally, the LDH adsorbent sludge was added into PP using a modified solvent mixing method. Thermal gravimetric analysis and ultraviolet (UV) absorption analysis of PP/Zn{sub 2}Al-AC97 LDHs nanocomposites suggested that the Zn{sub 2}Al-AC97 LDH can significantly improve the thermal stability and UV shielding ability of PP. This data demonstrated that it is very promising to resource the dye adsorbent sludge as multifunctional nanofiller for polymers.

Grading system for migrated lumbar disc herniation on sagittal magnetic resonance imaging. An agreement study

Energy Technology Data Exchange (ETDEWEB)

Ahn, Y.; Jeong, T.S. [Gachon University Gil Medical Center, Department of Neurosurgery, Incheon (Korea, Republic of); Lim, T.; Jeon, J.Y. [Gachon University Gil Medical Center, Department of Radiology, Incheon (Korea, Republic of)

2018-01-15

Migrated lumbar disc herniations (LDHs) in the sagittal plane are common. Disc migration grading can be applied as a useful measurement tool in the diagnosis, treatment, and outcome evaluation of migrated LDH. No study has evaluated the reliability of migrated LDH grading. We evaluated the reliability and functionality of the current magnetic resonance imaging (MRI) grading system for migrated LDH. We assessed a six-level grading system developed based on sagittal MRI and graded according to the direction (rostral and caudal) and degree (low, high, and very high) of disc migration. One-hundred and one migrated LDHs treated with minimally invasive endoscopic discectomy were analyzed independently by two experienced radiologists. Intraobserver and interobserver agreements were assessed by kappa statistics. The most common migrated LDH grade was grade 4 (30.94%; caudal, low-grade migration). Rostral and caudal migrations were more common in the upper and lower lumbar levels, respectively. Interobserver agreement in the grading of migrated LDH was good at both the first (kappa = 0.737) and second assessment (kappa = 0.657). The intraobserver agreement for reader 1 was very good (kappa = 0.827) and for reader 2 was good (kappa = 0.620). The current grading system for migrated LDH was found to be reliable and functional with good interobserver and intraobserver agreement. It may be useful in the interpretation of disc migration patterns and outcomes of various minimally invasive surgical procedures. (orig.)

Conformal Coating of Cobalt-Nickel Layered Double Hydroxides Nanoflakes on Carbon Fibers for High-performance Electrochemical Energy Storage Supercapacitor Devices

KAUST Repository

Warsi, Muhammad Farooq

2014-07-01

High specific capacitance coupled with the ease of large scale production is two desirable characteristics of a potential pseudo-supercapacitor material. In the current study, the uniform and conformal coating of nickel-cobalt layered double hydroxides (CoNi0.5LDH,) nanoflakes on fibrous carbon (FC) cloth has been achieved through cost-effective and scalable chemical precipitation method, followed by a simple heat treatment step. The conformally coated CoNi0.5LDH/FC electrode showed 1.5 times greater specific capacitance compared to the electrodes prepared by conventional non-conformal (drop casting) method of depositing CoNi0.5LDH powder on the carbon microfibers (1938 Fg-1 vs 1292 Fg-1). Further comparison of conformally and non-conformally coated CoNi0.5LDH electrodes showed the rate capability of 79%: 43% capacity retention at 50 Ag-1 and cycling stability 4.6%: 27.9% loss after 3000 cycles respectively. The superior performance of the conformally coated CoNi0.5LDH is mainly due to the reduced internal resistance and fast ionic mobility between electrodes as compared to non-conformally coated electrodes which is evidenced by EIS and CV studies. © 2014 Elsevier Ltd.

Ethanol Sensor of CdO/Al2O3/CeO2 Obtained from Ce-DOPED Layered Double Hydroxides with High Response and Selectivity

Science.gov (United States)

Xu, Dongmei; Guan, Meiyu; Xu, Qinghong; Guo, Ying; Wang, Yao

2013-04-01

In this paper, Ce-doped CdAl layered double hydroxide (LDH) was first synthesized and the derivative CdO/Al2O3/CeO2 composite oxide was prepared by calcining Ce-doped CdAl LDH. The structure, morphology and chemical state of the Ce doped CdAl LDH and CdO/Al2O3/CeO2 were also investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), solid state nuclear magnetic resonance (SSNMR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing properties of CdO/Al2O3/CeO2 to ethanol were further studied and compared with CdO/Al2O3 prepared from CdAl LDH, CeO2 powder as well as the calcined Ce salt. It turns out that CdO/Al2O3/CeO2 sensor shows best performance in ethanol response. Besides, CdO/Al2O3/CeO2 possesses short response/recovery time (12/72 s) as well as remarkable selectivity in ethanol sensing, which means composite oxides prepared from LDH are very promising in gas sensing application.

Mechanochemically synthesized LiAlOx catalyst for aqueous aldol condensation of furfural with acetone

Directory of Open Access Journals (Sweden)

Stepanova L. N.

2017-10-01

Full Text Available In the present study, the mechanochemical method is proposed for synthesis of LiAl-layered double hydroxides (LDHs. This method is eco-friendly and allows obtaining LiAl-LDH under relatively mild conditions (centripetal acceleration of milling bodies 300 m s-2 and in a short period of time (15 minutes. The structures of as-prepared LiAl-LDH, LiAl-mixed oxide (calcined LDH and “activated” LiAl-LDH obtained after rehydration of the corresponding mixed oxide were confirmed by X-ray diffraction. The basicity of LiAlOx was measured by temperature-programmed desorption of CO2 and double isotherm technique. According to data obtained, LiAl-mixed oxide has a significant higher carbon dioxide adsorption capacity compared to MgAlmixed oxides prepared by conventional co-precipitation method. This indicates a large amount of basic surface sites with different strength (strong, medium and weak for Li-containing systems. The formation of “activated” LiAl-LDH having Bronsted basic sites (OH groups in the interlayer space provides an increased catalytic activity of LiAlOx in the reaction of aqueous-phase aldol condensation between furfural and acetone.

Biochemical Parameters of Guinea Pig Perilymph Sampled According to Scala and Following Sound Presentation

Science.gov (United States)

Gershbein, Leon L.; Manshio, Dennis T.; Shurrager, Phil S.

1974-01-01

Guinea pigs were exposed to sound varying from 2 to 8 kHz in frequency and 80-100 dB (SPL) in intensity for periods of 1 hr. The biochemical parameters, glucose, sodium, total protein, and the glycolytic enzymes, aldolase, phosphohexose isomerase, and total LDH as well as isozymes of the latter were ascertained for blood serum, perilymph, and, in some instances, cerebrospinal fluid. The three enzymes occurred at lower levels in perilymph as compared to blood serum. Except for a small difference in serum total protein, sound presentation incurred no significant effect on any of the above parameters. Definite differences in several metabolites were discerned for perilymph sampled according to scala and which were independent of the respective acoustical treatments. Thus, as compared to the scale tympani, the scala vestibuli perilymph displayed a higher glucose content and a diminished total LDH level and of the latter isozymes, LDH1 ranged lower and LDH2, higher. As further evidence pointing to cerebrospinal fluid as the possible origin of perilymph, similarities in glucose contents and LDH isozyme patterns were noted for both fluids. PMID:4470918

Lactate Dehydrogenase and Oxidative Stress Activity in Primary Open-Angle Glaucoma Aqueous Humour

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Predrag Jovanović

2010-02-01

Full Text Available Lactate dehydrogenase (LDH and lactate are some of the hypoxy biochemical parameters. Extracellular activity of this enzyme increases under the condition of oxidative stress, since the cell integrity can be disrupted during the lipid peroxidation process. Subsequently that leads to the increase level of the lactic acid and lactic acid salts. The objective of this investigation is establishing the level of LDH, LDH1 (HBDH and the lactate concentration in aqueous humour in patients with primary open-angle glaucoma.Biochemical analysis have been made by enzymatic-colometric method (lactate and UV-kinetic method (LDH and HBDH in aqueous humour of 30 patients (42 eyes with primary open-angle glaucoma (POAG and 30 patients (40 eyes with cataract (the control group.The increased values of lactate and the activity of LDH and HBDH enzyme in aqueous humour of POAG patients in correlation with the control group are the results not only of oxidative stress but also of hypoxy and the mitochondry oxidative function (p<0,001.The increased activity of the examined biochemical parameters in the aqueous humour of the POAG patients points to the fact that other mechanisms, besides IOP, have a role in glaucoma pathogenesis.

Synthesis and selective IR absorption properties of iminodiacetic-acid intercalated MgAl-layered double hydroxide

International Nuclear Information System (INIS)

Wang Lijing; Xu Xiangyu; Evans, David G.; Duan Xue; Li Dianqing

2010-01-01

An MgAl-NO 3 -layered double hydroxide (LDH) precursor has been prepared by a method involving separate nucleation and aging steps (SNAS). Reaction with iminodiacetic acid (IDA) under weakly acidic conditions led to the replacement of the interlayer nitrate anions by iminodiacetic acid anions. The product was characterized by XRD, FT-IR, TG-DTA, ICP, elemental analysis and SEM. The results show that the original interlayer nitrate anions of LDHs precursor were replaced by iminodiacetic acid anions and that the resulting intercalation product MgAl-IDA-LDH has an ordered crystalline structure. MgAl-IDA-LDH was mixed with low density polyethylene (LDPE) using a masterbatch method. LDPE films filled with MgAl-IDA-LDH showed a higher mid to far infrared absorption than films filled with MgAl-CO 3 -LDH in the 7-25 μm range, particularly in the key 9-11 μm range required for application in agricultural plastic films. - Graphical abstract: Intercalation of iminodiacetic acid (IDA) anions in a MgAl-NO 3 -layered double hydroxide host leads to an enhancement of its infrared absorbing ability for application in agricultural plastic films.

Conformal Coating of Cobalt-Nickel Layered Double Hydroxides Nanoflakes on Carbon Fibers for High-performance Electrochemical Energy Storage Supercapacitor Devices

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