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Luigi Da Vià, Carlo Recchi, Thomas E Davies, Nicholas Greeves, Jose A Lopez-Sanchez
The visible-light-mediated photo-catalytic selective valorisation of glucose using TiO2-supported Ag nanoparticles is shown for the first time. The optimisation of the catalyst composition, substrate-to-catalyst ratio and reaction medium proved that a near total suppression of the mineralisation pathway could be achieved with a selectivity to partial oxidation products and small-chain monosaccharides as high as 98 %. The primary products were determined to be gluconic acid, arabinose, erythrose, glyceraldehyde and formic acid...
November 22, 2016: ChemCatChem
Man-Yeon Choi, Siew Bee Tang, Seung-Joon Ahn, Kaushalya G Amarasekare, Peter Shearer, Jana C Lee
In this study, we investigated the effects of non-nutritive sugars and sugar alcohols on the survivorship of spotted wing drosophila, Drosophila suzukii, and found erythritol and erythrose as potentially insecticidal to the fly. In a dose-dependent study, erythritol and erythrose significantly reduced fly longevity, with 100% mortality with 1, 0.5, 0.1 & 0.05M doses after feeding for 7days. When sucrose and erythritol solutions were provided separately to flies for 7days, there was no effect on survivorship regardless of erythritol concentrations...
April 5, 2017: Journal of Insect Physiology
Sun-Mi Shin, Thinh-Phat Cao, Jin Myung Choi, Seong-Bo Kim, Sang-Jae Lee, Sung Haeng Lee, Dong-Woo Lee
There is currently little information on nonphosphorylated sugar epimerases, which are of potential interest for producing rare sugars. We found a gene (the TM0416 gene) encoding a putative d-tagatose-3-epimerase-related protein from the hyperthermophilic bacterium Thermotoga maritima We overexpressed the TM0416 gene in Escherichia coli and purified the resulting recombinant protein for detailed characterization. Amino acid sequence alignment and a structural similarity search revealed that TM0416 is a putative nonphosphorylated sugar epimerase...
May 15, 2017: Applied and Environmental Microbiology
Ulrich Weininger
NMR-spectroscopy enables unique experimental studies on protein dynamics at atomic resolution. In order to obtain a full atom view on protein dynamics, and to study specific local processes like ring-flips, proton-transfer, or tautomerization, one has to perform studies on amino-acid side chains. A key requirement for these studies is site-selective labeling with (13)C and/or (1)H, which is achieved in the most general way by using site-selectively (13)C-enriched glucose (1- and 2-(13)C) as the carbon source in bacterial expression systems...
March 2017: Journal of Biomolecular NMR
Claire L Windle, Katie J Simmons, James R Ault, Chi H Trinh, Adam Nelson, Arwen R Pearson, Alan Berry
Natural enzymes are constructed from the 20 proteogenic amino acids, which may then require posttranslational modification or the recruitment of coenzymes or metal ions to achieve catalytic function. Here, we demonstrate that expansion of the alphabet of amino acids can also enable the properties of enzymes to be extended. A chemical mutagenesis strategy allowed a wide range of noncanonical amino acids to be systematically incorporated throughout an active site to alter enzymic substrate specificity. Specifically, 13 different noncanonical side chains were incorporated at 12 different positions within the active site of N-acetylneuraminic acid lyase (NAL), and the resulting chemically modified enzymes were screened for activity with a range of aldehyde substrates...
March 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Naresh Balachandran, Frederick To, Paul J Berti
3-Deoxy-d-arabino-heptulosonate-7-phosphate (DAHP) synthase catalyzes an aldol-like reaction of phosphoenolpyruvate (PEP) with erythrose 4-phosphate (E4P) to form DAHP in the first step of the shikimate biosynthetic pathway. DAHP oxime, in which an oxime replaces the ketone, is a potent inhibitor, with Ki = 1.5 μM. Linear free energy relationship (LFER) analysis of DAHP oxime inhibition using DAHP synthase mutants revealed an excellent correlation between transition state stabilization and inhibition. The equations of LFER analysis were rederived to formalize the possibility of proportional, rather than equal, changes in the free energies of transition state stabilization and inhibitor binding, in accord with the fact that the majority of LFER analyses in the literature demonstrate nonunity slopes...
January 31, 2017: Biochemistry
Cristina E A Sousa, António M P Ribeiro, António Gil Fortes, Nuno M F S A Cerqueira, Maria J Alves
A new d-erythrose 1,3-dioxane derivative was synthesized from d-glucose and found to be a highly stereoselective template as a dipolarophile. Different 1,3-dipoles of allenyl-type were employed, giving different regioselectivities, depending on its nature; the regioselectivity is complete with alkyl azides and phenyldiazomethane, but is inexistence with nitrile oxides. Computational studies were performed to understand the mechanisms of cycloadditions. All the studied cycloadditions were found to be concerted involving small free activation energies and are all exoenergonic...
January 9, 2017: Journal of Organic Chemistry
Vanina A Cosenza, Diego A Navarro, Carlos A Stortz
Two polysaccharide fractions isolated from Hypnea musciformis after room temperature- and hot water extraction, soluble after KCl precipitation of the more abundant carrageenans, were subfractionated by ion-exchange chromatography eluting with increasing concentrations of NaCl. The lowest NaCl concentration (0.2M) eluted agarans. The dl-hybrids (or mixtures) eluted at intermediate concentrations of NaCl. The d/l-galactose ratio and the sulfate proportion increased with the NaCl concentration. Different types of substitution were present, mainly at C-3 with sulfate, Xyl and methylated Gal stubs, as well as low amounts of 3,6-AnGal...
February 10, 2017: Carbohydrate Polymers
Shiqin Yu, Manuel R Plan, Gal Winter, Jens O Krömer
para-Hydroxy benzoic acid (PHBA) is the key component for preparing parabens, a common preservatives in food, drugs, and personal care products, as well as high-performance bioplastics such as liquid crystal polymers. Pseudomonas putida KT2440 was engineered to produce PHBA from glucose via the shikimate pathway intermediate chorismate. To obtain the PHBA production strain, chorismate lyase UbiC from Escherichia coli and a feedback resistant 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase encoded by gene aroG(D146N) were overexpressed individually and simultaneously...
2016: Frontiers in Bioengineering and Biotechnology
Naresh Balachandran, Maren Heimhalt, Peter Liuni, Frederick To, Derek J Wilson, Murray S Junop, Paul J Berti
3-Deoxy-d-arabinoheptulosonate-7-phosphate (DAHP) synthase catalyzes the first step in the shikimate pathway. It catalyzes an aldol-like reaction of phosphoenolpyruvate (PEP) with erythrose 4-phosphate (E4P) to form DAHP. The kinetic mechanism was rapid equilibrium sequential ordered ter ter, with the essential divalent metal ion, Mn(2+), binding first, followed by PEP and E4P. DAHP oxime, in which an oxime group replaces the keto oxygen, was a potent inhibitor, with Ki = 1.5 ± 0.4 μM, though with residual activity at high inhibitor concentrations...
December 6, 2016: Biochemistry
Marek Szczepaniak, Jerzy Moc
We present a comprehensive benchmark computational study which has explored a complete path of the anomerization reaction of bare d-erythrose involving a pair of the low-energy α- and β-furanose anomers, the former of which was observed spectroscopically (Cabezas et al., Chem. Commun. 2013, 49, 10826). We find that the ring opening of the α-anomer yields the most stable open-chain tautomer which step is followed by the rotational interconversion of the open-chain rotamers and final ring closing to form the β-anomer...
February 15, 2017: Journal of Computational Chemistry
W Wu, J Xie, H Zhang
Dietary fibers (DFs), widely used as food additives to replace fat, can benefit metabolic disorders. Soluble and highly fermentable inulin (INU) and insoluble and less fermentable microcrystalline cellulose (MCC) have hypolipidemic or cholesterol-lowering effects, respectively. The current study was aimed at identifying plasma metabolite signatures and metabolic pathways associated with inclusion of DFs with different physiochemical properties, which will lead to a better understanding of functional pathways for DFs to improve metabolic health...
November 9, 2016: Food & Function
Oskar Popik, Monika Pasternak-Suder, Sebastian Baś, Jacek Mlynarski
Herein we report a short and efficient protocol for the synthesis of naturally occurring higher-carbon sugars-sedoheptulose (d-altro-hept-2-ulose) and d-glycero-l-galacto-oct-2-ulose-from readily available sugar aldehydes and dihydroxyacetone (DHA). The key step includes a diastereoselective organocatalytic syn-selective aldol reaction of DHA with d-erythrose and d-xylose, respectively. The methodology presented can be expanded to the synthesis of various higher sugars by means of syn-selective carbon-carbon-bond-forming aldol reactions promoted by primary-based organocatalysts...
December 2015: ChemistryOpen
H Ishizuka, K Tokuoka, T Sasaki, H Taniguchi
An erythrose reductase was obtained from the cells of an Aureobasidium sp. mutant having high erythritol-producing activity. This enzyme was purified 600-fold over the cell-free extract by ammonium sulfate precipitation, ion exchange chromatography, affinity chromatography, and hydrophobic chromatography. It gave a single band on polyacrylamide gel electrophoresis, and had a molecular weight of 37,000 and an isoelectric point of 4.8. This enzyme had maximum reductive activity at 45°C and pH 6.5. The optimum pH of the oxidative reaction was 9...
January 1992: Bioscience, Biotechnology, and Biochemistry
Zhandong Li, Lifeng An, Hao Li, ShaoPeng Wang, You Zhou, Fei Yuan, Lin Li
Nasopharyngeal cancer or nasopharyngeal carcinoma (NPC) is the most common cancer originating in the nasopharynx. The factors that induce nasopharyngeal cancer are still not clear. Additional information about the chemicals or genes related to nasopharyngeal cancer will promote a better understanding of the pathogenesis of this cancer and the factors that induce it. Thus, a computational method NPC-RGCP was proposed in this study to identify the possible relevant chemicals and genes based on the presently known chemicals and genes related to nasopharyngeal cancer...
2016: Scientific Reports
Arpan Modi, Nitish Kumar, Subhash Narayanan
Stevia (Stevia rebaudiana Bertoni) is a medicinal plant having sweet, diterpenoid glycosides known as steviol glycosides which are 200-300 times sweeter than sucrose (0.4 % solution). They are synthesized mainly in the leaves via plastid localized 2-C-methyl-D-erythrose-4-phosphate pathway (MEP pathway). Fifteen genes are involved in the formation of these glycosides. In the present protocol, a method for the quantification of transcripts of these genes is shown. The work involves RNA extraction and cDNA preparation, and therefore, procedures for the confirmation of DNA-free cDNA preparation have also been illustrated...
2016: Methods in Molecular Biology
Aniek D van der Woude, Ruth Perez Gallego, Angie Vreugdenhil, Vinod Puthan Veetil, Tania Chroumpi, Klaas J Hellingwerf
BACKGROUND: Erythritol is a polyol that is used in the food and beverage industry. Due to its non-caloric and non-cariogenic properties, the popularity of this sweetener is increasing. Large scale production of erythritol is currently based on conversion of glucose by selected fungi. In this study, we describe a biotechnological process to produce erythritol from light and CO2, using engineered Synechocystis sp. PCC6803. METHODS: By functionally expressing codon-optimized genes encoding the erythrose-4-phosphate phosphatase TM1254 and the erythrose reductase Gcy1p, or GLD1, this cyanobacterium can directly convert the Calvin cycle intermediate erythrose-4-phosphate into erythritol via a two-step process and release the polyol sugar in the extracellular medium...
April 8, 2016: Microbial Cell Factories
Juliana Ferreira, Vera C M Duarte, Jennifer Noro, António Gil Fortes, Maria J Alves
Different electron-rich dienophiles were combined with the imine obtained from 2,4-O-benzylidene-d-erythrose and p-anisidine furnishing enantiomerically pure tetrahydroquinolines, by inverse electron-demand [4π + 2π] cycloaddition. The imine was also reacted with 2-substituted electron-rich 1,3-butadienes giving the diastereomeric pure product, resulting from the normal electron demand cycloaddition. The facial selectivity of both processes is proposed on the basis of a 1,4-relationship between the hydroxyl group and the nitrogen atom in the chiral N-(p-methoxyphenyl)imine derivative...
March 14, 2016: Organic & Biomolecular Chemistry
Penelope J Cross, Logan C Heyes, Shiwen Zhang, Ali Reza Nazmi, Emily J Parker
Neisseria meningitidis 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (NmeDAH7PS) adopts a homotetrameric structure consisting of an extensive and a less extensive interface. Perturbation of the less extensive interface through a single mutation of a salt bridge (Arg126-Glu27) formed at the tetramer interface of all chains resulted in a dimeric DAH7PS in solution, as determined by small angle X-ray scattering, analytical ultracentrifugation and analytical size-exclusion chromatography. The dimeric NmeDAH7PSR126S variant was shown to be catalytically active in the aldol-like condensation reaction between D-erythrose 4-phosphate and phosphoenolpyruvate, and allosterically inhibited by L-phenylalanine to the same extent as the wild-type enzyme...
2016: PloS One
Tatiana Bilova, Elena Lukasheva, Dominic Brauch, Uta Greifenhagen, Gagan Paudel, Elena Tarakhovskaya, Nadezhda Frolova, Juliane Mittasch, Gerd Ulrich Balcke, Alain Tissier, Natalia Osmolovskaya, Thomas Vogt, Ludger A Wessjohann, Claudia Birkemeyer, Carsten Milkowski, Andrej Frolov
Glycation is the reaction of carbonyl compounds (reducing sugars and α-dicarbonyls) with amino acids, lipids, and proteins, yielding early and advanced glycation end products (AGEs). The AGEs can be formed via degradation of early glycation intermediates (glycoxidation) and by interaction with the products of monosaccharide autoxidation (autoxidative glycosylation). Although formation of these potentially deleterious compounds is well characterized in animal systems and thermally treated foods, only a little information about advanced glycation in plants is available...
April 1, 2016: Journal of Biological Chemistry
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