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Dehalogenation

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https://www.readbyqxmd.com/read/28639018/test-of-aerobic-tce-degradation-by-willows-salix-viminalis-and-willows-inoculated-with-tce-cometabolizing-strains-of-burkholderia-cepacia
#1
Lauge Peter Westergaard Clausen, Mette Martina Broholm, Ulrich Gosewinkel, Stefan Trapp
Trichloroethylene (TCE) is a widespread soil and groundwater pollutant and clean-up is often problematic and expensive. Phytoremediation may be a cost-effective solution at some sites. This study investigates TCE degradation by willows (S. viminalis) and willows inoculated with three strains of B. cepacia (301C, PR1-31 and VM1330-pTOM), using chloride formation as an indicator of dehalogenation. Willows were grown in non-sterile, hydroponic conditions for 3 weeks in chloride-free nutrient solution spiked with TCE...
June 21, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28618195/novel-reductive-dehalogenases-from-the-marine-sponge-associated-bacterium-desulfoluna-spongiiphila
#2
Jie Liu, Nora Lopez, Young-Beom Ahn, Tatyana Goldberg, Yana Bromberg, Lee J Kerkhof, Max M Häggblom
Desulfoluna spongiiphila strain AA1 is an organohalide respiring bacterium, isolated from the marine sponge Aplysina aerophoba, that can use brominated and iodinated phenols, in addition to sulfate and thiosulfate as terminal electron acceptors. The genome of Desulfoluna spongiiphila strain AA1 is approximately 6.5 Mb. Three putative reductive dehalogenase (rdhA) genes involved in respiratory metabolism of organohalides were identified within the sequence. Conserved motifs found in respiratory reductive dehalogenases (a twin arginine translocation signal sequence and two iron-sulfur clusters) were present in all three putative AA1 rdhA genes...
June 15, 2017: Environmental Microbiology Reports
https://www.readbyqxmd.com/read/28587829/pegylation-with-the-thiosuccinimido-butylamine-linker-significantly-increases-the-stability-of-haloalkane-dehalogenase-dhaa
#3
Yuan-Zhong Zhao, Wei-Li Yu, He Zheng, Xuan Guo, Nan Guo, Tao Hu, Jin-Yi Zhong
Haloalkane dehalogenase (HLD) can catalyze the hydrolytic dehalogenation of halogenated compounds. However, HLD suffers from the poor stability to resist the environmental stress. PEGylation is an effective approach to enhance the stability of enzymes. The linker is an important stabilization factor of PEGylation. Thus, the linkers of the PEGylated HLD were optimized to improve the stability of HLD in the present study. The PEGylated haloalkane dehalogenase DhaAs with methylamine (Ml), carbamate (Cm) and thiosuccinimido butylamine (Tb) linkers were prepared, respectively...
June 3, 2017: Journal of Biotechnology
https://www.readbyqxmd.com/read/28566709/targeted-radionuclide-therapy-with-astatine-211-oxidative-dehalogenation-of-astatobenzoate-conjugates
#4
David Teze, Dumitru-Claudiu Sergentu, Valentina Kalichuk, Jacques Barbet, David Deniaud, Nicolas Galland, Rémi Maurice, Gilles Montavon
(211)At is a most promising radionuclide for targeted alpha therapy. However, its limited availability and poorly known basic chemistry hamper its use. Based on the analogy with iodine, labelling is performed via astatobenzoate conjugates, but in vivo deastatination occurs, particularly when the conjugates are internalized in cells. Actually, the chemical or biological mechanism responsible for deastatination is unknown. In this work, we show that the C-At "organometalloid" bond can be cleaved by oxidative dehalogenation induced by oxidants such as permanganates, peroxides or hydroxyl radicals...
May 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28553478/nature-s-hydrides-rapid-reduction-of-halocarbons-by-folate-model-compounds
#5
Michael K Denk, Nicholas S Milutinović, Katherine M Marczenko, Natalie M Sadowski, Athanasios Paschos
Halocarbons R-X are reduced to hydrocarbons R-H by folate model compounds under biomimetic conditions. The reactions correspond to a halide-hydride exchange with the methylenetetrahydrofolate (MTHF) models acting as hydride donors. The MTHF models are also functional equivalents of dehalohydrogenases but, unlike these enzymes, do not require a metal cofactor. The reactions suggest that halocarbons have the potential to act as endocrinological disruptors of biochemical pathways involving MTHF. As a case in point, we observe the rapid reaction of the MTHF models with the inhalation anaesthetic halothane...
March 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28530808/%C3%AE-halo-amides-as-competent-latent-enolates-direct-catalytic-asymmetric-mannich-type-reaction
#6
Bo Sun, Pandur Venkatesan Balaji, Naoya Kumagai, Masakatsu Shibasaki
α-Halogenated carbonyl compounds are susceptible to dehalogenation and thus largely neglected as enolate precursors in catalytic enantioselective C-C bond-forming reactions. By merging the increased stability of the α-C-halogen bond of amides and the direct enolization methodology of the designed amide, we explored a direct catalytic asymmetric Mannich-type reaction of α-halo 7-azaindoline amides with N-carbamoyl imines. All α-halo substituents, α-F, -Cl, -Br, -I amides, were tolerated to provide the Mannich-adducts in a highly stereoselective manner without undesirable dehalogenation...
June 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28521164/biotransformation-of-hexabromocyclododecanes-with-hexachlorocyclohexane-transforming-sphingobium-chinhatense-strain-ip26
#7
Norbert V Heeb, Andreas Grubelnik, Birgit Geueke, Hans-Peter E Kohler, Peter Lienemann
Bacterial evolution has resulted in the appearance of several Sphingomonadacea strains that gained the ability to metabolize hexachlorocyclohexanes (HCHs). HCHs have been widely used as pesticides but were banned under the Stockholm Convention on persistent organic pollutants (POPs) in 2009. Here we present evidence for bacterial transformation reactions of hexabromocyclododecanes (HBCDs), which are structurally related to HCHs. HBCDs were used as flame retardants. They are now also considered as POPs and their production and use is restricted since 2013...
May 11, 2017: Chemosphere
https://www.readbyqxmd.com/read/28499743/resolution-of-the-uncertainty-in-the-kinetic-mechanism-for-the-trans-3-chloroacrylic-acid-dehalogenase-catalyzed-reaction
#8
Jamison P Huddleston, Susan C Wang, Kenneth A Johnson, Christian P Whitman
trans- and cis-3-Chloroacrylic acid dehalogenase (CaaD and cis-CaaD, respectively) catalyze the hydrolytic dehalogenation of their respective isomers and represent key steps in the bacterial conversion of 1,3-dichloropropene to acetaldehyde. In prior work, a kinetic mechanism for the CaaD-catalyzed reaction could not be unequivocally determined because (1) the order of product release could not be determined and (2) the fluorescence factor for the enzyme species, E*PQ (where P = bromide and Q = malonate semialdehyde, the two products of the reaction) could not be assigned...
June 1, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28463483/a-field-trial-of-tce-phytoremediation-by-genetically-modified-poplars-expressing-cytochrome-p450-2e1
#9
Emily K Legault, C Andrew James, Keith Stewart, Indulis Muiznieks, Sharon L Doty, Stuart E Strand
A controlled field study was performed to evaluate the effectiveness of transgenic poplars for phytoremediation. Three hydraulically contained test beds were planted with 12 transgenic poplars, 12 wild type (WT) poplars, or left unplanted, and dosed with equivalent concentrations of trichloroethylene (TCE). Removal of TCE was enhanced in the transgenic tree bed, but not to the extent of the enhanced removal observed in laboratory studies. Total chlorinated ethene removal was 87% in the CYP2E1 bed, 85% in the WT bed, and 34% in the unplanted bed in 2012...
June 6, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28431360/contrasting-dual-c-cl-isotope-fractionation-offers-potential-to-distinguish-reductive-chloroethene-transformation-from-breakdown-by-permanganate
#10
Eylem Doğan-Subaşı, Martin Elsner, Shiran Qiu, Stefan Cretnik, Siavash Atashgahi, Orfan Shouakar-Stash, Nico Boon, Winnie Dejonghe, Leen Bastiaens
cis-1,2-Dichloroethene (cis-DCE) and trichloroethene (TCE) are persistent, toxic and mobile pollutants in groundwater systems. They are both conducive to reductive dehalogenation and to oxidation by permanganate. In this study, the potential of dual element (C, Cl) compound specific isotope analyses (CSIA) for distinguishing between chemical oxidation and anaerobic reductive dechlorination of cis-DCE and TCE was investigated. Well-controlled cis-DCE degradation batch tests gave similar carbon isotope enrichment factors εC (‰), but starkly contrasting dual element isotope slopes Δδ(13)C/Δδ(37)Cl for permanganate oxidation (εC=-26‰±6‰, Δδ(13)C/Δδ(37)Cl≈-125±47) compared to reductive dechlorination (εC=-18‰±4‰, Δδ(13)C/Δδ(37)Cl≈4...
April 18, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28425677/microbial-dehalogenation-an-annotated-selection-of-world-wide-web-sites-relevant-to-the-topics-in-environmental-microbiology
#11
Lawrence P Wackett
No abstract text is available yet for this article.
April 20, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28424844/microbial-reductive-dehalogenation-of-trihalomethanes-by-a-dehalobacter-containing-co-culture
#12
Siyan Zhao, Matthew J Rogers, Jianzhong He
Trihalomethanes such as chloroform and bromoform, although well-known as a prominent class of disinfection by-products, are ubiquitously distributed in the environment due to widespread industrial usage in the past decades. Chloroform and bromoform are particularly concerning, of high concentrations detected and with long half-lives up to several hundred days in soils and groundwater. In this study, we report a Dehalobacter- and Desulfovibrio-containing co-culture that exhibits dehalogenation of chloroform (~0...
April 19, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28421054/isolation-and-characterization-of-dehalobacter-sp-strain-tecb1-including-identification-of-tcba-a-novel-tetra-and-trichlorobenzene-reductive-dehalogenase
#13
Ricardo Alfán-Guzmán, Haluk Ertan, Mike Manefield, Matthew Lee
Dehalobacter sp. strain TeCB1 was isolated from groundwater near Sydney, Australia, that is polluted with a range of organochlorines. The isolated strain is able to grow by reductive dechlorination of 1,2,4,5-tetrachlorobenzene to 1,3- and 1,4-dichlorobenzene with 1,2,4-trichlorobenzene being the intermediate daughter product. Transient production of 1,2-dichlorobenzene was detected with subsequent conversion to monochlorobenzene. The dehalogenation capability of strain TeCB1 to respire 23 alternative organochlorines was examined and shown to be limited to the use of 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28391934/enhanced-debromination-of-4-bromophenol-by-the-uv-sulfite-process-efficiency-and-mechanism
#14
Bihuang Xie, Xuchun Li, Xianfeng Huang, Zhe Xu, Weiming Zhang, Bingcai Pan
Halogenated aromatic compounds have attracted increasing concerns due to their toxicity and persistency in the environment, and dehalogenation is one of the promising treatment and detoxification methods. Herein, we systematically studied the debromination efficiency and mechanism of para-bromophenol (4-BP) by a recently developed UV/sulfite process. 4-BP underwent rapid degradation with the kinetics accelerated with the increasing sulfite concentration, pH (6.1-10) and temperature, whereas inhibited by dissolved oxygen and organic solvents...
April 2017: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/28378313/microbial-degradation-of-chloroethenes-a-review
#15
REVIEW
Iva Dolinová, Martina Štrojsová, Miroslav Černík, Jan Němeček, Jiřina Macháčková, Alena Ševců
Contamination by chloroethenes has a severe negative effect on both the environment and human health. This has prompted intensive remediation activity in recent years, along with research into the efficacy of natural microbial communities for degrading toxic chloroethenes into less harmful compounds. Microbial degradation of chloroethenes can take place either through anaerobic organohalide respiration, where chloroethenes serve as electron acceptors; anaerobic and aerobic metabolic degradation, where chloroethenes are used as electron donors; or anaerobic and aerobic co-metabolic degradation, with chloroethene degradation occurring as a by-product during microbial metabolism of other growth substrates, without energy or carbon benefit...
May 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28347952/anaerobic-biodegradation-of-emerging-organic-contaminants-in-the-aquatic-environment
#16
REVIEW
Ann-Kathrin Ghattas, Ferdinand Fischer, Arne Wick, Thomas A Ternes
Although strictly anaerobic conditions prevail in several environmental compartments, up to now, biodegradation studies with emerging organic contaminants (EOCs), such as pharmaceuticals and personal care products, have mainly focused on aerobic conditions. One of the reasons probably is the assumption that the aerobic degradation is more energetically favorable than degradation under strictly anaerobic conditions. Certain aerobically recalcitrant contaminants, however, are biodegraded under strictly anaerobic conditions and little is known about the organisms and enzymatic processes involved in their degradation...
June 1, 2017: Water Research
https://www.readbyqxmd.com/read/28314194/electrocatalytic-reduction-of-low-concentration-thiamphenicol-and-florfenicol-in-wastewater-with-multi-walled-carbon-nanotubes-modified-electrode
#17
Dongli Deng, Fei Deng, Bobin Tang, Jinzhong Zhang, Jiang Liu
The electrocatalytic reduction of thiamphenicol (TAP) and florfenicol (FF) was investigated with multi-walled carbon nanotubes (MWCNTs) modified electrode. MWCNTs was dispersed in pure water with the assistance of dihexadecyl phosphate (DHP), and then modified on glassy carbon electrode (GCE). The electrocatalytic reduction conditions, such as bias voltage, supporting electrolyte and its initial pH, and the initial concentrations of TAP and FF, were also optimized. The experimental results indicated that the removal efficiencies of 2mgL(-1) TAP and FF in 0...
March 7, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28294243/initiating-radical-reactions-with-non-thermal-plasmas
#18
Yury Gorbanev, Dirk Leifert, Armido Studer, Deborah O'Connell, Victor Chechik
Non-thermal plasmas were used as radical initiators in three radical chain reactions: dehalogenation, 5-exo-trig cyclisation and trifluoromethylation with the Togni II reagent. The use of non-volatile solvents (or solvent-free conditions) gave high yields in all reactions under optimised conditions. Short reaction times and mild conditions make this method an attractive alternative to conventional radical initiators.
March 15, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28282120/general-and-efficient-c-c-bond-forming-photoredox-catalysis-with-semiconductor-quantum-dots
#19
Jill A Caputo, Leah C Frenette, Norman Zhao, Kelly L Sowers, Todd D Krauss, Daniel J Weix
Photoredox catalysis has become an essential tool in organic synthesis because it enables new routes to important molecules. However, the best available molecular catalysts suffer from high catalyst loadings and rely on precious metals. Here we show that colloidal nanocrystal quantum dots (QDs) can serve as efficient and robust, precious-metal free, photoassisted redox catalysts. A single-sized CdSe quantum dot (3.0 ± 0.2 nm) can replace several different dye catalysts needed for five different photoredox reactions (β-alkylation, β-aminoalkylation, dehalogenation, amine arylation, and decarboxylative radical formation)...
March 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28281345/singlet-versus-triplet-excited-state-mediated-photoinduced-dehalogenation-reactions-of-itraconazole-in-acetonitrile-and-aqueous-solutions
#20
Ruixue Zhu, Ming-de Li, Lili Du, David Lee Phillips
Photoinduced dehalogenation of the antifungal drug itraconazole (ITR) in acetonitrile (ACN) and ACN/water mixed solutions was investigated using femtosecond and nanosecond time-resolved transient absorption (fs-TA and ns-TA, respectively) and nanosecond time-resolved resonance Raman spectroscopy (ns-TR(3)) experiments. An excited resonance energy transfer is found to take place from the 4-phenyl-4,5-dihydro-3H-1,2,4-triazol-3-one part of the molecule to the 1,3-dichlorobenzene part of the molecule when ITR is excited by ultraviolet light...
March 29, 2017: Journal of Physical Chemistry. B
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