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Decarboxylation

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https://www.readbyqxmd.com/read/27914260/the-extent-of-fermentative-transformation-of-phenolic-compounds-in-the-bioanode-controls-exoelectrogenic-activity-in-a-microbial-electrolysis-cell
#1
Xiaofei Zeng, Maya A Collins, Abhijeet P Borole, Spyros G Pavlostathis
Phenolic compounds in hydrolysate/pyrolysate and wastewater streams produced during the pretreatment of lignocellulosic biomass for biofuel production present a significant challenge in downstream processes. Bioelectrochemical systems are increasingly recognized as an alternative technology to handle biomass-derived streams and to promote water reuse in biofuel production. Thus, a thorough understanding of the fate of phenolic compounds in bioanodes is urgently needed. The present study investigated the biotransformation of three structurally similar phenolic compounds (syringic acid, SA; vanillic acid, VA; 4-hydroxybenzoic acid, HBA), and their individual contribution to exoelectrogenesis in a microbial electrolysis cell (MEC) bioanode...
November 27, 2016: Water Research
https://www.readbyqxmd.com/read/27913417/development-of-an-improved-system-for-the-generation-of-knock-out-mutants-of-amycolatopsis-sp-atcc-39116
#2
Florian Meyer, Hilke Pupkes, Alexander Steinbüchel
The Gram-positive actinomycete Amycolatopsis sp. ATCC 39116 is used for the industrial production of natural vanillin. Previously, the only gene deletion performed in this strain targeted the gene vdh coding for a vanillin dehydrogenase. The generation of this mutant suffered from a high number of illegitimate recombinations and the low rate of homologous recombination. To alleviate this, we constructed an optimized deletion system based on a modified suicide vector. Thereby, we were able to enhance the rate of homologous integration from less than 1% of the analyzed clones to 20% or 50% depending on the targeted gene...
December 2, 2016: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/27912178/spectrometric-assay-for-horseradish-peroxidase-activity-based-on-the-linkage-of-conjugated-system-formed-by-oxidative-decarboxylation
#3
Masaki Yamaguchi, Shingo Sato
Horseradish peroxidase (HRP)-catalyzed oxidation of 2,2-bis[3-acethylfilicinic acid-5-yl]acetic acid (BAFA, 4) produces Dehydro-3,3'-diacetyl-5,5'-methylenedifilicinic acid (DDMF, 3). A new photometric hydrogen donor (4) for peroxidase (POD)-catalyzed oxidation was demonstrated to be potentially useful for spectrocolorimetric and spectrofluorometric determination of HRP. Our developed colorimetric (absorption at 483nm) and fluorometric (emission at 529nm) systems both gave a linear calibration curve for HRP (y=0...
November 13, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/27910129/synthesis-of-c-14-radiolabeled-glucagon-receptor-antagonist-and-its-use-in-a-human-mass-balance-study
#4
Boris A Czeskis, Darlene K Satonin
The synthesis of the radiolabeled glucagon receptor antagonist 1-[(14) C] was accomplished based on decarboxylative iodination of acid 2 followed by "reattachment" of (14) C carboxylic function. The method allowed a significant reduction in the number of steps in preparation of the radiolabeled compound. Iodide 4, obtained by the halodecarboxylation, was converted to cyanide 5-[(14) C], which was hydrolyzed to provide the radiolabeled acid 2-[(14) C]. Coupling with β-alanine fragment and hydrolysis of ester 6-[(14) C] completed the synthesis of the target molecule 1-[(14) C]...
December 1, 2016: Journal of Labelled Compounds & Radiopharmaceuticals
https://www.readbyqxmd.com/read/27897423/decarboxylative-4-2-cycloaddition-by-synergistic-palladium-and-organocatalysis
#5
Lars A Leth, Florian Glaus, Marta Meazza, Liang Fu, Mathias K Thøgersen, Emma A Bitsch, Karl Anker Jørgensen
A novel reaction based on synergistic catalysis, combining palladium- and organocatalysis has been developed. The palladium catalyst activates vinyl benzoxazinanones via a decarboxylation to undergo a [4+2] cycloaddition with iminium-ion activated α,β-unsaturated aldehydes. The reaction is demonstrated to proceed for a number of combinations of vinyl benzoxazinanones reacting with α,β-unsaturated aldehydes, providing highly substituted vinyl tetrahydroquinolines in good to high yields, and excellent enantio- and diastereoselectivities (>98 % ee and >20:1 d...
December 5, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27897198/mitochondrial-control-through-nutritionally-regulated-global-histone-h3-lysine-4-demethylation
#6
Maria Soloveychik, Mengshu Xu, Olga Zaslaver, Kwanyin Lee, Ashrut Narula, River Jiang, Adam P Rosebrock, Amy A Caudy, Marc D Meneghini
Histone demethylation by Jumonji-family proteins is coupled with the decarboxylation of α-ketoglutarate (αKG) to yield succinate, prompting hypotheses that their activities are responsive to levels of these metabolites in the cell. Consistent with this paradigm we show here that the Saccharomyces cerevisiae Jumonji demethylase Jhd2 opposes the accumulation of H3K4me3 in fermenting cells only when they are nutritionally manipulated to contain an elevated αKG/succinate ratio. We also find that Jhd2 opposes H3K4me3 in respiratory cells that do not exhibit such an elevated αKG/succinate ratio...
November 29, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27885628/bcaa-metabolism-and-nh3-homeostasis
#7
M E Conway, S M Hutson
The branched chain amino acids (BCAA) are essential amino acids required not only for growth and development, but also as nutrient signals and as nitrogen donors to neurotransmitter synthesis and glutamate/glutamine cycling. Transamination and oxidative decarboxylation of the BCAAs are catalysed by the branched-chain aminotransferase proteins (BCATm, mitochondrial and BCATc, cytosolic) and the branched-chain α-keto acid dehydrogenase enzyme complex (BCKDC), respectively. These proteins show tissue, cell compartmentation, and protein-protein interactions, which call for substrate shuttling or channelling and nitrogen transfer for oxidation to occur...
2016: Advances in Neurobiology
https://www.readbyqxmd.com/read/27884080/decomposition-products-of-glycidyl-esters-of-fatty-acids-by-heating
#8
Wataru Kimura, Yasushi Endo
In this study, decomposition products of glycidyl palmitate (GP) of fatty acids heated at high temperature such as deep frying were investigated. When GP and tripalmitin (TP) were heated at 180 and 200 °C, they were decreased with heating time. The weight of GP was less than that of TP, although both GP and TP were converted to polar compounds after heating. The decomposition rate of GP was higher than TP. Both GP and TP produced considerable amounts of hydrocarbons and aldehydes during heating. Aldehydes produced from GP and TP included saturated aldehydes with carbon chain length of 3-10, while hydrocarbons consisted of carbon chain length of 8-15...
November 25, 2016: Bioscience, Biotechnology, and Biochemistry
https://www.readbyqxmd.com/read/27883908/scalable-preparation-characterization-and-application-of-alkali-treated-starch-as-a-new-organic-base-catalyst
#9
Fatemeh Tamaddon, MohammadTaghi KazemiVarnamkhasti
Preparation, characterization, and application of alkali starch (AS) given by dry co-grinding of starch and alkali is described in this work. Grinding using a mortar (agate) and pestle or, more conveniently, a ball mill has been found to be satisfactory for the preparation of the AS. The AS products were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) and x-ray fluorescence (XRF) analyses. The base capacities of ASs were 4.25-4.45 mmol/g, respectively...
November 16, 2016: Carbohydrate Research
https://www.readbyqxmd.com/read/27882368/an-unusual-co-crystal-%C3%AE-2-dcpm-ag2-%C3%AE-2-o2ch-%C3%AE-2-no3-2%C3%A2-%C3%AE-2-dcpm-2ag4-%C3%AE-2-no3-4-and-its-connection-to-the-selective-decarboxylation-of-formic-acid-in-the-gas-phase
#10
Athanasios Zavras, Jonathan M White, Richard A J O'Hair
ESI/MS of an acetonitrile solution containing a mixture of AgNO3 :  bis(dicyclohexylphosphino)methane (dcpm, L) : NaO2CH in a molar ratio of 2 : 1 : 1 gave an abundant peak due to [LAg2(O2CH)](+) and a minor peak assigned as [L2Ag4(O2CH)3](+). When this acetonitrile solution was frozen and layered with diethyl ether and left undisturbed for six days, crystalline material suitable for X-ray crystallography was identified and separated from amorphous solids. Single crystal X-ray diffraction revealed an unusual co-crystal consisting of two discrete tetranuclear silver clusters [(μ2-dcpm)Ag2(μ2-O2CH)(η(2)-NO3)]2·[(μ2-dcpm)2Ag4(μ2-NO3)4]...
November 24, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27874862/a-decarboxylative-approach-for-regioselective-hydroarylation-of-alkynes
#11
Jing Zhang, Ruja Shrestha, John F Hartwig, Pinjing Zhao
Regioselective activation of aromatic C-H bonds is a long-standing challenge for arene functionalization reactions such as the hydroarylation of alkynes. One possible solution is to employ a removable directing group that activates one of several aromatic C-H bonds. Here we report a new catalytic method for regioselective alkyne hydroarylation with benzoic acid derivatives during which the carboxylate functionality directs the alkyne to the ortho-C-H bond with elimination in situ to form a vinylarene product...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27872963/microbial-production-of-amino-acid-related-compounds
#12
Volker F Wendisch
Corynebacterium glutamicum is the workhorse of the production of proteinogenic amino acids used in food and feed biotechnology. After more than 50 years of safe amino acid production, C. glutamicum has recently also been engineered for the production of amino acid-derived compounds, which find various applications, e.g., as synthons for the chemical industry in several markets including the polymer market. The amino acid-derived compounds such as non-proteinogenic ω-amino acids, α,ω-diamines, and cyclic or hydroxylated amino acids have similar carbon backbones and functional groups as their amino acid precursors...
November 22, 2016: Advances in Biochemical Engineering/biotechnology
https://www.readbyqxmd.com/read/27860140/decarboxylative-peptide-macrocyclization-through-photoredox-catalysis
#13
Stefan J McCarver, Jennifer X Qiao, Joseph Carpenter, Robert M Borzilleri, Michael A Poss, Martin D Eastgate, Michael Miller, David W C MacMillan
A method for the decarboxylative macrocyclization of peptides bearing N-terminal Michael acceptors has been developed. This synthetic method enables the efficient synthesis of cyclic peptides containing γ-amino acids and is tolerant of functionalities present in both natural and non-proteinogenic amino acids. Linear precursors ranging from 3 to 15 amino acids cyclize effectively under this photoredox method. To demonstrate the preparative utility of this method in the context of bioactive molecules, we synthesized COR-005, a somatostatin analogue that is currently in clinical trials...
November 17, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27860002/phso2-scf2-h-a-shelf-stable-easily-scalable-reagent-for-radical-difluoromethylthiolation
#14
Dianhu Zhu, Xinxin Shao, Xin Hong, Long Lu, Qilong Shen
A new shelf-stable and easily scalable difluoromethylthiolating reagent S-(difluoromethyl) benzenesulfonothioate (PhSO2 SCF2 H) was developed. PhSO2 SCF2 H is a powerful reagent for radical difluoromethylthiolation of aryl and alkyl boronic acids, decarboxylative difluoromethylthiolation of aliphatic acids, and a phenylsulfonyl-difluoromethylthio difunctionalization of alkenes under mild reaction conditions.
November 17, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27859719/decarboxylation-as-the-key-step-in-c-c-bond-forming-reactions
#15
Debabrata Maiti, Tuhin Patra
C-C bond forming reactions incarnate the core of organic synthesis because of their fundamental applications towards molecular diversity and complexity. In recent years, use of carboxylic acid as one of the coupling partners in place of conventional organometallic reagents has seen an upsurge due to its potency to generate the similar organometallic intermediates after decarboxylation. This review provides an overview on most recent progress in the field of C-C bond formation involving decarboxylation as a key step...
November 18, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27855668/identification-and-characterization-of-two-new-5-keto-4-deoxy-d-glucarate-dehydratases-decarboxylases
#16
André Pick, Barbara Beer, Risa Hemmi, Rena Momma, Jochen Schmid, Kenji Miyamoto, Volker Sieber
BACKGROUND: Hexuronic acids such as D-galacturonic acid and D-glucuronic acid can be utilized via different pathways within the metabolism of microorganisms. One representative, the oxidative pathway, generates α-keto-glutarate as the direct link entering towards the citric acid cycle. The penultimate enzyme, keto-deoxy glucarate dehydratase/decarboxylase, catalyses the dehydration and decarboxylation of keto-deoxy glucarate to α-keto-glutarate semialdehyde. This enzymatic reaction can be tracked continuously by applying a pH-shift assay...
November 17, 2016: BMC Biotechnology
https://www.readbyqxmd.com/read/27853966/remediation-of-cu-metal-induced-accelerated-fenton-reaction-by-potato-peels-bio-sorbent
#17
Rafia Azmat, Sumeira Moin, Ailyan Saleem
This article has allied exposure to Ecological Particulate Matter (EPM) and its remediation using potato peel surface (PPC) bio-sorbent on two important edible crops Spinacia oleracea and Luffa acutangula. Fenton reaction acceleration was one of the major stress oxidation reactions as a consequence of iron and copper toxicity, which involve in the formation of hydroxyl radical (OH) through EPM. Results showed that the oxidative stress encouraged by Cu in both species that recruits the degradation of photosynthetic pigments, initiating decline in growth, reduced leaf area and degrade proteins...
December 0: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/27844075/correction-transition-metal-free-decarboxylative-alkylation-reactions
#18
Ping Liu, Guanghui Zhang, Peipei Sun
Correction for 'Transition metal-free decarboxylative alkylation reactions' by Ping Liu et al., Org. Biomol. Chem., 2016, DOI: 10.1039/c6ob02101h.
November 15, 2016: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/27834209/metabolite-pools-and-carbon-flow-during-c4-photosynthesis-in-maize-13co2-labeling-kinetics-and-cell-type-fractionation
#19
Stéphanie Arrivault, Toshihiro Obata, Marek Szecówka, Virginie Mengin, Manuela Guenther, Melanie Hoehne, Alisdair R Fernie, Mark Stitt
Worldwide efforts to engineer C4 photosynthesis into C3 crops require a deep understanding of how this complex pathway operates. CO2 is incorporated into four-carbon metabolites in the mesophyll, which move to the bundle sheath where they are decarboxylated to concentrate CO2 around RuBisCO. We performed dynamic (13)CO2 labeling in maize to analyze C flow in C4 photosynthesis. The overall labeling kinetics reflected the topology of C4 photosynthesis. Analyses of cell-specific labeling patterns after fractionation to enrich bundle sheath and mesophyll cells revealed concentration gradients to drive intercellular diffusion of malate, but not pyruvate, in the major CO2-concentrating shuttle...
November 7, 2016: Journal of Experimental Botany
https://www.readbyqxmd.com/read/27831491/structure-and-function-of-an-ancestral-type-%C3%AE-decarboxylating-dehydrogenase-from-thermococcus-kodakarensis
#20
Tetsu Shimizu, Lulu Yin, Ayako Yoshida, Yuusuke Yokooji, Shin-Ichi Hachisuka, Takaaki Sato, Takeo Tomita, Hiromi Nishida, Haruyuki Atomi, Tomohisa Kuzuyama, Makoto Nishiyama
β-Decarboxylating dehydrogenases, which are involved in central metabolism, are considered to have diverged from a common ancestor with broad substrate specificity. In a molecular phylogenetic analysis of 183 β-decarboxylating dehydrogenase homologs from 84 species, TK0280 from Thermococcus kodakarensis was selected as a candidate for an ancestral-type β-decarboxylating dehydrogenase. The biochemical characterization of recombinant TK0280 revealed that the enzyme exhibited dehydrogenase activities toward homoisocitrate, isocitrate, and 3-isopropylmalate, which correspond to key reactions involved in the lysine biosynthetic pathway, tricarboxylic acid cycle, and leucine biosynthetic pathway, respectively...
November 9, 2016: Biochemical Journal
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