Consulta: subjectFacets:"Depolymerization"
Registros recuperados: 9
Data/hora: 08/06/2024 18:05:26

Phenolic compounds: production of phenolic compounds from lignin.
Provedor de dados: 14
Autores: RODRIGUES, C. M.
TC202
Tipo: Folders
Palavras-chave: Lignin; Depolymerization.
Ano: 2022
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/1139327

Ultrasonic depolymerization of an exopolysaccharide produced by a bacterium isolated from a deep-sea hydrothermal vent polychaete annelid
Provedor de dados: 5
Autores: Petit, Anne-celine; Noiret, Nicolas; Guezennec, Jean; Gondrexon, N; Colliec-jouault, Sylvia.
Low frequency ultrasound was used to depolymerize a high-molecular-weight exopolysaccharide (EPS) produced by a deep-sea hydrothermal bacterium Alteromonas macleodii subsp. fijiensis biovar deepsane. The influence of several parameters was examined including the duration of ultrasonic irradiation, EPS concentration. reaction temperature and volume of the sonicated solution. With the aim of optimizing the depolyrnerization, the native EPS was simultaneously treated with hydrogen peroxide and ultrasound. This study identified the sonication conditions that produce low-molecular-weight derivatives from the native EPS (&gt;10(6) Da) with good reproducibility. (C) 2006 Elsevier B.V. All rights reserved.
Tipo: Text
Palavras-chave: Exopolysaccharide; Depolymerization; Ultrasound.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2123.pdf

Assessment of biochemical methods to detect enzymatic depolymerization of polysaccharides
Provedor de dados: 5
Autores: Rigouin, Coraline; Delbarre Ladrat, Christine; Sinquin, Corinne; Colliec-jouault, Sylvia; Dion, M.
To find biocatalyst allowing depolymerization of new polysaccharides, one needs to get a sensitive and well adapted method to a screening program. This led us to compare biochemical methods of detection of the depolymerization. Currently used methods such as reducing sugars assays, double bond monitoring or molecular weight determination were tested to follow the kinetic of depolymerization with different enzyme / polysaccharide couples. The range of concentrations of assorted enzymes allowed us to identify the most sensitive and appropriate method to detect polysaccharide degradation. Reducing sugars assays are quantitative, sensitive and almost usable with all kind of polysaccharide but some compounds may interfere with them. When polysaccharide is...
Tipo: Text
Palavras-chave: Detection; Enzyme; Depolymerization; Carbohydrate.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2008/publication-4723.pdf

Enzymatic depolymerization of the GY785 exopolysaccharide produced by the deep-sea hydrothermal bacterium Alteromonas infernus : structural study and enzyme activity assessment
Provedor de dados: 5
Autores: Zykwinska, Agata; Berre, Ludivine Tripon-le; Sinquin, Corinne; Ropartz, David; Rogniaux, Helene; Colliec-jouault, Sylvia; Delbarre-ladrat, Christine.
Polysaccharides have attracted much attention due to their interesting physico-chemical and also biological properties that are explored in food, cosmetic and pharmaceutical industries. GY785 exopolysaccharide (EPS) presenting an unusual structure is secreted by the deep-sea hydrothermal bacterium, Alteromonas infernus. Low-molecular weight (LMW) derivatives obtained by chemical depolymerization of the native high molecular weight (HMW) EPS were previously shown to exhibit biological properties similar to glycosaminoglycans (GAG). In the present study, in order to generate well defined derivatives with a better control of the depolymerization, an enzymatic approach was applied for the first time. Various commercially available enzymes were firstly screened...
Tipo: Text
Palavras-chave: Exopolysaccharide; Enzyme; Depolymerization; Oligosaccharide; Mass spectrometry.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00423/53458/54352.pdf

Etude d'oligosaccharides bioactifs issus d'exopolysaccharides bactériens : obtention, caractérisation et relation structure/fonction
Provedor de dados: 5
Autores: Roger, Olivier.
Unusual exopolysaccharides (EPS) produced by heterotrophic aerobic and mesophilic bacteria originating from hydrothermal vent, were reviewed as a new source of polysaccharidic structures endowed with innovative biological properties. The first step of this study was the structure determination of the EPS GY785, synthesized by Alteromonas infernus. A highly branched nonasaccharidic repetitive unit was identified using chemical modifications and nuclear magnetic resonance spectroscopy. This 106 g/mol polysaccharide is composed of glucose, galactose, glucuronic acid, galacturonic acid, and contains a single branched ramification and one sulphate group.  The second step was the preparation of low molecular weight bioactive polysaccharides presenting interest...
Tipo: Text
Palavras-chave: Phosphorylation; Sulphation; Depolymerization; NMR spectroscopy; Structure; Deep sea hydrothermal vent; Bacteria; Exopolysaccharides; Activité anticoagulante; Phosphatation; Sulfatation; Dépolymérisation; Spectroscopie de RMN; Structure; Sources hydrothermales; Bactéries; Exopolysaccharides.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/these-622.pdf

Characterization, chemical modifications and in vitro anticoagulant properties of an exopolysaccharide produced by Alteromonas infernus
Provedor de dados: 5
Autores: Colliec-jouault, Sylvia; Chevolot, Lionel; Helley, Dominique; Ratiskol, Jacqueline; Bros, Andrée; Sinquin, Corinne; Roger, Olivier; Fischer, Anne-marie.
A new low-molecular-weight 'heparin-like' component was obtained from an exopolysaccharide produced by a mesophilic strain found in deep-sea hydrothermal vents. Data concerning the structure of the native high-molecular-weight exopolysaccharide (10(6) g/mol, 10% sulfate content) are reported for the first time. Two depolymerization processes were used to obtain low-molecular-weight (24-35 x 10(3) g/mol) oversulfated fractions (sulfate content 20 or 40%), Nuclear magnetic resonance studies indicated that after sulfation (40%), the low-molecular-weight fraction obtained by free radical depolymerization was less sulfated in the 6-O-position than the fraction depolymerized by acid hydrolysis. The free radical depolymerized product also had sulfated residues in...
Tipo: Text
Palavras-chave: Sulfation; Sulfated polysaccharide; Serpin; Heparin like; Depolymerization; Anticoagulant activity; Affinity co electrophoresis.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/2001/publication-2111.pdf

Decrease in dynamic viscosity and average molecular weight of alginate from Laminaria digitata during alkaline extraction
Provedor de dados: 5
Autores: Vauchel, Peggy; Arhaliass, Abdellah; Legrand, Jack; Kaas, Raymond; Baron, Regis.
Alginates are natural polysaccharides that are extracted from brown seaweeds and widely used for their rheological properties. The central step in the extraction protocol used in the alginate industry is the alkaline extraction, which requires several hours. In this study, a significant decrease in alginate dynamic viscosity was observed after 2 h of alkaline treatment. Intrinsic viscosity and average molecular weight of alginates from alkaline extractions 1-4 h in duration were determined, indicating depolymerization of alginates: average molecular weight decreased significantly during the extraction, falling by a factor of 5 between 1 and 4 h of extraction. These results suggested that reducing extraction time could enable preserving the rheological...
Tipo: Text
Palavras-chave: Laminaria digitata; Intrinsic viscosity; Depolymerization; Average molecular weight; Alkaline extraction; Alginate.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-4060.pdf

Modifications d'un exopolysaccharide biosynthétisé par une bactérie issue des écosystèmes Hydrothermaux profonds
Provedor de dados: 5
Autores: Petit, Anne-celine.
Le travail présenté dans ce mémoire concerne la modification d'un exopolysaccharide (EPS), l'HYD 657, biosynthétisé par une bactérie issue des écosystèmes hydrothermaux profonds. Ce polysaccharide d'un poids moléculaire de 1,8.106 Da est composé de 40-50% d'oses neutres et de 30- 40% d'acides uroniques. L'hypothèse de structure la plus probable décrit son unité de répétition comme un undécasaccharide possédant 3 ramifications courtes. Cet EPS, sous sa forme native, a déjà fait l'objet d'une étude approfondie en vue d'applications dans le domaine de la cosmétique pour ses propriétés apaisantes en application topique cutanée.  Pour élargir le spectre d'applications de cet EPS, la réduction de sa masse molaire a été envisagée.  La première partie décrit la...
Tipo: Text
Palavras-chave: Oxidation; Sulfation; Esterification; Metallic catalysts; Sonochemistry; Deep sea hydrothermal; Depolymerization; Exopolysaccharide; Oxydation; Sulfatation; Estérification; Catalyse métallique; Ultrasons; Source hydrothermale; Dépolymérisation; Exopolysaccharide.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/these-1232.pdf

Mild-acid hydrolysis of a native polysulfated fraction from Acanthophora muscoides generates sulfated oligosaccharides displaying in vitro thrombin generation inhibition
Provedor de dados: 3
Autores: Rodrigues, José Ariévilo Gurgel; Queiroz, Ismael Nilo Lino de; Quinderé, Ana Luíza Gomes; Benevides, Norma Maria Barros; Tovar, Ana Maria Freire; Mourão, Paulo Antônio de Souza.
Acanthophora muscoides (Rhodophyta) has three polysulfated fractions    (Am-1, Am-2 and Am-3). Am-2 displayed anti-inflammation and serpin-independent anticoagulation; however, no effect of oligomers on thrombin-generation (TG) assay has been demonstrated. This study employed mild-acid hydrolysis to obtain low-molecular-size derivatives from Am-2 and compared in vitro inhibitory effects between intact Am-2 and its hydrolysates on a TG assay. The enzymatic extract was fractionated by DEAE-cellulose that revealed Am-2 eluted with 0.75-M NaCl containing sulfate (23%), hexoses (51%) and devoid of proteins, and indicating, by one-dimension nuclear magnetic resonance, structure of galactan similar to that of extract. The depolymerization with HCl (0.02 or...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Ciências Biológicas e Ambientais Rhodophyceae; Poli-aniônicos; Depolimerização; Trombina. Química de macromoléculas Rhodophyceae; Polyanionics; Depolymerization; Thrombin.
Ano: 2016
URL: http://periodicos.uem.br/ojs/index.php/ActaSciBiolSci/article/view/28257