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Delattre C.,CNRS Pascal Institute | Pierre G.,CNRS Pascal Institute | Gardarin C.,CNRS Pascal Institute | Traikia M.,CNRS Institute of Chemistry | And 3 more authors.
Carbohydrate Polymers | Year: 2014

A xanthouronic acid sodium salt called xanthouronan was produced from xanthan by regioselective oxidation with NaOCl/NaBr using 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) as catalyst. The efficiency of the one pot TEMPO-mediated oxidation was confirmed by HPAEC-PAD, 13C NMR, and FT-IR. The oxidation degree was close to 98% and the mass yield of this new polyglucuronic acid was higher than 90% (w/w). The macromolecular characterization of xanthouronan using SEC-MALLS showed a molecular size reduced by a third due to the oxidation treatment and the degree of polymerization (DP) of the xanthouronan form was about 665. The evaluation of the enzymatic degradation of this C-6 carboxylated xanthan by various polysaccharide hydrolases and one polysaccharide lyase showed its high resistant to biodegradation. The antioxidant activity of xanthouronan was also tested by using the 2,2′-diphenyl-1-picrylhydrazyle (DPPH) and hydroxyl radical procedures. At 1 g/L, xanthouronan presented 75% of the ascorbic acid antioxidant activity. © 2014 Elsevier Ltd.

Badel S.,University Blaise Pascal | Laroche C.,University Blaise Pascal | Gardarin C.,University Blaise Pascal | Petit E.,Laboratoire des Polysaccharides Microbiens et vegetaux | And 2 more authors.
Enzyme and Microbial Technology | Year: 2011

The activity of polysaccharide cleavage enzymes has usually been evaluated by qualitative plate screening methods and quantitative colorimetric or chromatographic assays. The recent development of protein engineering has shown the limits of these techniques when applied to high throughput screening. Here we propose a microplate method to measure the activity of polysaccharide cleavage enzymes through small variations in viscosity. Polysaccharide solutions are co-incubated with magnetic particles in enzyme buffers. The cleavage action of polymer-degrading enzymes increases the mobility of the particles in a magnetic field, even at low levels of enzyme activities. This reproducible, sensitive technique was used to evaluate enzymatic specificity towards substrates. BioFilm indices (BFI) determined by associated software were used to follow enzyme kinetics and measure the usual variables. © 2010 Elsevier Inc.

Elboutachfaiti R.,Laboratoire des Polysaccharides Microbiens et vegetaux | Delattre C.,GREENTECH Naturally | Petit E.,Laboratoire des Polysaccharides Microbiens et vegetaux | Michaud P.,University Blaise Pascal
Carbohydrate Polymers | Year: 2011

Totally unknown at the beginning of the nineties, polyglucuronic acids have aroused the interest of scientific community working with polysaccharides. These polyuronides, initially isolated from microorganisms, have been later identified in some complex cell walls such as those of green algae. The recent progresses in the regioselective oxidation of neutral glucans permits them to be obtained on a large scale under relatively mild conditions. At the same time, new enzymes able to degrade these polysaccharides have been identified leading notably to the description of a new polysaccharide lyase family. The different forms of polyglucuronic acids such as those of low molecular weight obtained after enzymatic degradation of β-(1,4)-polyglucuronic acids have been tested for biological activities with success. So, several industrial applications associated with these compounds have been patented. This review focuses on this class of polyuronides and the enzymes capable of cleaving them. © 2010 Elsevier Ltd. All rights reserved.

Pawlicki-Jullian N.,Laboratoire des Polysaccharides Microbiens et vegetaux | Courtois B.,Laboratoire des Polysaccharides Microbiens et vegetaux | Pillon M.,Laboratoire des Polysaccharides Microbiens et vegetaux | Lesur D.,French National Center for Scientific Research | And 4 more authors.
Research in Microbiology | Year: 2010

Nitrogen-fixing bacteria isolated from root nodules of Medicago plants growing in the 10 km zone around the Chernobyl nuclear power plant were screened for the production of new water-soluble acidic exopolysaccharides (EPSs). The different strains belonged to the Enteriobacteriaceae family (Enterobacter ludwigii, Raoultella terrigena, Klebsiella oxytoca), except for one which belonged to the Rhizobiaceae family (Sinorhizobium meliloti). All of the bacteria produced highly viscous EPS with an average molecular weight comprised between 1 × 106 and 3 × 106 Da. Five different compositions of EPS were characterized by physico-chemical analyses and 1H NMR spectroscopy: galactose/mannose (2/1), galactose/glucose (1/1), galactose/glucose/mannose (1/2/1), fucose/galactose/glucose (2/1/1) and fucose/galactose/glucose/mannose (2/2/1/1 or 1/1/2/4). Glucuronic acid, a charged monosaccharide, was also recovered in most of the different EPSs. © 2010 Elsevier Masson SAS.

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