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See detailEnzymatic synthesis of sugar esters obtained from renewable stabilized by dairy components.
Torezan, Gabriela; Ronkart, Sébastien; Paquot, Michel ULg et al

Poster (2007, October 11)

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See detailEnzymatic synthesis, surface and lipid interaction properties of novel rhamnolipids
Nott, Katherine ULg; Richard, Gaetan ULg; Deleu, Magali ULg

Conference (2013)

Amongst glycolipidid biosurfactants, rhamnolipids have drawn particular attention as they have several interesting biological properties such as antimicrobial, antiphytoviral, zoosporicidal and plant ... [more ▼]

Amongst glycolipidid biosurfactants, rhamnolipids have drawn particular attention as they have several interesting biological properties such as antimicrobial, antiphytoviral, zoosporicidal and plant defense elicitor activities [1-3]. It is generally recognised that these activities must be linked to the interaction of these molecules with constituents of biological membranes [4] but the detailed mechanism is far from being fully understood. The objective of this work is double. First, it aims to investigate a new strategy of synthesis for the production of novel rhamnolipids [5] that could exhibit properties as promising for industrial and environmental applications as their natural counterparts while avoiding the use of the pathogenic Pseudomonas aeruginosa for their production. Secondly, their basic surface properties (critical aggregation concentration, surface tension at CAC and interfacial behaviour of their monolayer) and their interaction with model membranes are investigated in relation with their structure in order to give insight about the mechanism of their biological actions. [1] Vatsa P. et al. Int. J. Mol. Sci. 2010;11:5095. [2] Varnier A-L. et al. Plant, Cell Environ. 2009;32:178. [3] Lang S. et al. Appl. Microbiol. Biotechn. 1999;51:22. [4] Aranda F.J. et al. Langmuir. 2007;23:2700. [5] Nott K. et al. Process Biochemistry, http://dx.doi.org/10.1016/j.procbio.2012.11.019 [less ▲]

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See detailENZYMATIC TRANSFORMATION OF DESULFO-GLUCOSINOLATES IN PURE NITRILES USING A RECOMBINANT beta-O-GLUCOSIDASE
Iori, R.; Wathelet, Jean-Paul ULg; Leoni, O. et al

Poster (1999)

The recombinant b-O-glucosidase (EC 3.2.1.21) from the thermophilic bacterium Tp8 does not catalyse glucosinolate degradation but transforms desulfo-glucosinolates viz. desulfo-sinigrin, desulfo ... [more ▼]

The recombinant b-O-glucosidase (EC 3.2.1.21) from the thermophilic bacterium Tp8 does not catalyse glucosinolate degradation but transforms desulfo-glucosinolates viz. desulfo-sinigrin, desulfo-gluconapin, desulfo-progoitrin, desulfo-epiprogoitrin, desulfo-glucotropaeolin, desulfogluconasturtiin, desulfo-sinalbin, desulfo-limnantin, desulfo-glucoerucin and desulfo-glucoiberin in the corresponding pure nitriles (GC purity: +/- 99%). Prop-3-enyl, but-3-enyl, (2R)-2-hydroxybut-3-enyl, (2S)-2-hydroxybut-3-enyl, benzyl, phenethyl, 4-hydroxybenzyl, 3-methoxybenzyl, 4-methylthiobutyl and 3-methylsulphinylpropyl cyanides have been respectively identified by GC-MS. This thermostable enzyme is very different from myrosinase, a b-S-glucosidase (EC 3.2.3.1) present in Brassicaceae, which easily hydrolyses glucosinolates producing mainly a mixture of isothiocyanates, nitriles and eventually thiones. This endogenous b-S-glucosidase is totally inactive towards desulfo-glucosinolates, while the b-O-glucosidase tested is not active with synthetic S-glucose substrates such as the p-nitrophenyl-S-glucose. It is the first time that a b-O-glucosidase has been found to hydrolyse natural S-glucose substrates such as desulfoglucosinolates. The possibility to produce pure nitriles by this way, especially chiral compounds ((2R)-2-hydroxybut-3-enyl, (2S)-2-hydroxybut-3-enyl...), appears to be interesting for application in fine chemistry. The effect of pH (2 to 9) and temperature (40 to 85°C) on the recombinant b-O-glucosidase activity has been determined with desulfo-sinigrin as substrate. Optimal activity of this thermostable enzyme is reached at pH 6. [less ▲]

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See detailEnzymatically prepared n-alkyl esters of glucuronic acid: The effect of freeze-drying conditions and hydrophobic chain length on thermal behavior
Blecker, Christophe ULg; Danthine, Sabine ULg; Petre, Maguy ULg et al

in Journal of Colloid & Interface Science (2008), 321(1), 154-158

In this work, some of the physicochemical properties of enzymatically prepared n-alkyl esters of glucuronic acid are presented. Two questions are addressed. The first concerns the influence of post ... [more ▼]

In this work, some of the physicochemical properties of enzymatically prepared n-alkyl esters of glucuronic acid are presented. Two questions are addressed. The first concerns the influence of post-purification freeze-drying condition's on octyl glucuronate thermotropic behavior. Depending on the amount of water added before freeze-drying, the alpha/beta anomeric ratio determined by H-1 NMR is affected and differences are observed in DSC thermograms probably due to polymorphism. The second question concerns the effect of hydrophobic chain length on the thermal behavior. An increase of both transition temperature and transition enthalpy is observed by increasing the number of carbon atoms in the alkyl chain (C8 < C10 < C12 < C14). This kind of results can provide relevant information for the processing and the practical use of these nonionic surfactants. (C) 2008 Elsevier Inc. All rights reserved. [less ▲]

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See detailEnzymatically prepared n-alkyl esters of glucuronic acid: The effect of hydrophobic chain length on surface properties
Blecker, Christophe ULg; Piccicuto, S.; Lognay, Georges ULg et al

in Journal of Colloid & Interface Science (2002), 247(2), 424-428

The effect of hydrophobic chain length on surface properties of enzymatically prepared n-alkyl esters of glucuronic acid are examined. Dynamic parameters from Hua and Rosen's mathematical model and ... [more ▼]

The effect of hydrophobic chain length on surface properties of enzymatically prepared n-alkyl esters of glucuronic acid are examined. Dynamic parameters from Hua and Rosen's mathematical model and equilibrium surface tension are presented for esters with octyl, decyl, dodecyl, and tetradecyl alkyl segments. Increasing the alkyl chain length has a significant influence on the surface activity. Decyl and dodecyl glucuronate exhibit an interesting adsorption speed associated with foaming capacity. Octyl glucuronate exhibits a micellar organization as its bulk concentration is over 10.68 mM. (C) 2002 Elsevier Science (USA). [less ▲]

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See detailEnzyme Activity Determination on Macromolecular Substrates by Isothermal Titration Calorimetry: Application to Mesophilic and Psychrophilic Chitinases
Lonhienne, T.; Baise, Etienne ULg; Feller, Georges ULg et al

in Biochimica et Biophysica Acta (2001), 1545(1-2), 349-56

Isothermal titration calorimetry has been applied to the determination of the kinetic parameters of chitinases (EC 3.2.1.14) by monitoring the heat released during the hydrolysis of chitin glycosidic ... [more ▼]

Isothermal titration calorimetry has been applied to the determination of the kinetic parameters of chitinases (EC 3.2.1.14) by monitoring the heat released during the hydrolysis of chitin glycosidic bonds. Experiments were carried out using two different macromolecular substrates: a soluble polymer of N-acetylglucosamine and the insoluble chitin from crab shells. Different experimental temperatures were used in order to compare the thermodependence of the activity of two chitinases from the psychrophile Arthrobacter sp. TAD20 and of chitinase A from the mesophile Serratia marcescens. The method allowed to determine unequivocally the catalytic rate constant k(cat), the activation energy (E(a)) and the thermodynamic activation parameters (DeltaG(#), DeltaH(#), DeltaS(#)) of the chitinolytic reaction on the soluble substrate. The catalytic activity has also been determined on insoluble chitin, which displays an effect of substrate saturation by chitinases. On both substrates, the thermodependence of the activity of the psychrophilic chitinases was lower than that observed with the mesophilic counterpart. [less ▲]

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See detailEnzyme Analysis of Thymic Nurse Cells
Defresne, Marie-Paule ULg; Plum, J.; De Smedt, M. et al

in Thymus (1988), 11(4), 221-30

Thymic nurse cells (TNC) were characterized according to their enzyme content. The following enzymes: Lactate dehydrogenase (LDH) isoenzymes, adenosine deaminase (ADA) and purine nucleoside phosphorylase ... [more ▼]

Thymic nurse cells (TNC) were characterized according to their enzyme content. The following enzymes: Lactate dehydrogenase (LDH) isoenzymes, adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) were evaluated. When the enzyme profile of the TNC were compared with the one found in the different thymocyte subpopulations, the ADA/PNP ratio was very low and similar to the early thymocytes, whereas the LDH isoenzymes approached the pattern of the cortical thymocytes. This enzyme profile suggests that the enzyme content of the TNC is dependent on the presence of at least two different thymocyte subpopulations, the early thymocytes and the cortical thymocytes. [less ▲]

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See detailEnzyme function at low temperatures in psychrophiles
Feller, Georges ULg

in Thomas, T.; Siddiqui, K. S. (Eds.) Protein Adaptation in Extremophiles (2008)

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See detailEnzyme Immobilization in Nanoparticles produced by Inverse Microemulsion Polymerization
Daubresse, Catherine; Grandfils, Christian ULg; Jérôme, Robert ULg et al

in Journal of Colloid & Interface Science (1994), 168

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See detailEnzyme immobilization in reactive nanoparticles produced by inverse microemulsion polymerization
Daubresse, Catherine; Grandfils, Christian ULg; Jérôme, Robert ULg et al

in Colloid and Polymer Science (1996), 274(5), 482-489

This paper deals with the immobilization of alkaline phosphatase by physical entrapment within colloidal particles produced by inverse microemulsion polymerization. Functionality has been imparted to the ... [more ▼]

This paper deals with the immobilization of alkaline phosphatase by physical entrapment within colloidal particles produced by inverse microemulsion polymerization. Functionality has been imparted to the nanoparticle surface by copolymerization of acrylamide (the main monomer), N,N'-methylene-bis-acrylamide (the cross-linking agent) with either N-acryloyl-l,6-diamino-hexane (an amine promoter) or acrylic acid (a carboxylic acid promoter). The effect of the functions comonomers on the size and zeta potential of the reactive latexes has been studied. Integrity of the immobilized enzyme has been ascertained from its catalytic activity towards hydrolysis of p-nitrophenyl-phosphate. [less ▲]

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See detailEnzyme-Histochemical Detection of a Chymase-Like Proteinase within Bovine Mucosal and Connective Tissue Mast Cells
Jolly, Sandra ULg; Detilleux, Johann ULg; Coignoul, Freddy ULg et al

in Journal of Comparative Pathology (2000), 122(Feb-Apr), 155-162

The presence of chymase-like proteinase in bovine mast cells was investigated by an enzyme-histochemical technique (naphthol-AS-D-chloroacetate as substrate) in normal skin, primary bronchus, lung and ... [more ▼]

The presence of chymase-like proteinase in bovine mast cells was investigated by an enzyme-histochemical technique (naphthol-AS-D-chloroacetate as substrate) in normal skin, primary bronchus, lung and duodenum. The counts and distribution of chymase-positive and toluidine blue-positive mast cells were compared by means of successive staining. Mast cells with chymase-like activity were detected in all areas, but their proportion was greater in connective than mucosal tissues, with the exception of the skin. These results contrast with those obtained in rodents, in which chymase-like proteinases are detected in all tissues and also in all mast cells. Bovine mast cells are closer to those of human beings, in which chymase-containing mast cells predominate in connective tissues, including skin. The results suggest that more than one chymase subset is present, at least in duodenum. The possible occurrence of dual-specific chymase mast cells, as in other ruminants, is discussed. [less ▲]

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See detailEnzyme-linked immunoassay (ELISA) for connective tissue components.
Rennard, S. I.; Berg, R.; Martin, G. R. et al

in Analytical Biochemistry (1980), 104(1), 205-14

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See detailAn enzyme-linked immunoassay for direct measurement of the gelatin-binding capacity of human plasma fibronectin
Damas, Pierre ULg; Adam, A.; Closset, Jean ULg et al

in Journal of Immunological Methods (1986), 91

A new solid-phase enzyme immunoassay measuring the gelatin-binding capacity of plasma fibronectin has been developed. This assay is based on the direct and high-affinity interaction between fibronectin ... [more ▼]

A new solid-phase enzyme immunoassay measuring the gelatin-binding capacity of plasma fibronectin has been developed. This assay is based on the direct and high-affinity interaction between fibronectin and gelatin coated to polyvinyl chloride plates. The amount of fibronectin bound to gelatin is then measured by sequential incubation with a specific rabbit anti-human fibronectin antiserum, with horseradish peroxidase-conjugated goat anti-rabbit IgG antibodies and with substrate. The final degradation of the substrate is read at 492-650 nm in an ELISA processor. The assay allows the accurate detection of fibronectin concentrations ranging from 1 to 20 micrograms/ml, is inhibited by the addition of gelatin to plasma, is highly reproducible (interplate CV less than 10%), requires 100 microliter of plasma only and has been fully automated. Significant linear correlations were noted between total antigenic fibronectin (measured by laser nephelometry) and fibronectin gelatin-binding capacity in plasma from 310 blood donors. Both parameters were higher in men than in women and significantly increased according to age. Dissociation between immunoreactive fibronectin and fibronectin gelatin-binding capacity was observed in two polytraumatized patients. This enzyme immunoassay therefore provides a new method to investigate functional alterations of the gelatin-binding domain of fibronectin in various pathological conditions. [less ▲]

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See detailL’enzyme11β-HSD1 : une nouvelle cible potentielle pour le traitement du diabète de type 2 et des maladies métaboliques liées à l’obésité
SCHEEN, André ULg; BECK, Emmanuel ULg

in Diabète et Obésité (2013), 8

The 11 beta-hydroxysteroid dehydrogenase type 1 (11βHSD1) enzyme promotes the local conversion from cortisone to cortisol, especially in the adipose tissue and the liver. It may play a role in the ... [more ▼]

The 11 beta-hydroxysteroid dehydrogenase type 1 (11βHSD1) enzyme promotes the local conversion from cortisone to cortisol, especially in the adipose tissue and the liver. It may play a role in the pathophysiology of abdominal obesity and the metabolic syndrome, both showing some similarities with the Cushing syndrome. Synthetic selective inhibitors of 11βHSD1 are currently in development with encouraging preliminary results that remain, however, to be further improved. Selective inhibitors of 11βHSD1 may represent an innovative approach in the pharmacological management of obesity, metabolic syndrome and type 2 diabetes. [less ▲]

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See detailLes enzymes et leur utilisation en biotechnologie industrielle
Galonde, Nadine ULg

Poster (2010, May 22)

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See detailEnzymes from Cold-Adapted Microorganisms. The Class C Beta-Lactamase from the Antarctic Psychrophile Psychrobacter Immobilis A5
Feller, Georges ULg; Zekhnini, Z.; Lamotte-Brasseur, J. et al

in European Journal of Biochemistry (1997), 244(1), 186-91

A heat-labile beta-lactamase has been purified from culture supernatants of Psychrobacter immobilis A5 grown at 4 degrees C and the corresponding chromosomal ampC gene has been cloned and sequenced. All ... [more ▼]

A heat-labile beta-lactamase has been purified from culture supernatants of Psychrobacter immobilis A5 grown at 4 degrees C and the corresponding chromosomal ampC gene has been cloned and sequenced. All structural and kinetic properties clearly relate this enzyme to class C beta-lactamases. The kinetic parameters of P. immobilis beta-lactamase for the hydrolysis of some beta-lactam antibiotics are in the same range as the values recorded for the highly specialized cephalosporinases from pathogenic mesophilic bacteria. By contrast, the enzyme displays a low apparent optimum temperature of activity and a reduced thermal stability. Structural factors responsible for the latter property were analysed from the three-dimensional structure built by homology modelling. The deletion of proline residues in loops, the low number of arginine-mediated H-bonds and aromatic-aromatic interactions, the lower global hydrophobicity and the improved solvent interactions through additional surface acidic residues appear to be the main determinants of the enzyme flexibility. [less ▲]

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See detailEnzymes from psychrophiles
Feller, Georges ULg; Narinx, Emmanuel; Arpigny, Jean Louis et al

Conference (1996)

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See detailEnzymes from psychrophiles : an unachieved adaptation
Gerday, Charles ULg; Feller, Georges ULg

Conference (2000)

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See detailEnzymes from psychrophilic organisms
Feller, Georges ULg; Narinx, E.; Arpigny, J. L. et al

in FEMS Microbiology Reviews (1996), 18(2-3), 189-202

Psychrophilic organisms such as micro-organisms and other ectothermic species living in polar, deep- sea or any constantly low temperature environments, produce enzymes adapted to function at low ... [more ▼]

Psychrophilic organisms such as micro-organisms and other ectothermic species living in polar, deep- sea or any constantly low temperature environments, produce enzymes adapted to function at low temperature. These enzymes are characterized by a high catalytic efficiency at low and moderate temperatures but are rather thermolabile. Due to their high specific activity and their rapid inactivation at temperatures as low as 30 degrees C, they offer, along with the producing micro-organisms, a great potential in biotechnology. The molecular basis of the adaptation of cold cu-amylase, subtilisin, triose phosphate isomerase from Antarctic bacteria and of trypsin from fish living in North Atlantic and in Antarctic sea waters have been studied. The comparison of the 3D structures obtained either by protein modelling or by X-ray crystallography (North Atlantic trypsin) with those of their mesophilic counterparts indicates that the molecular changes tend to increase the flexibility of the structure by a weakening of the intramolecular interactions and by an increase of the interactions with the solvent. For each enzyme, the most appropriate strategy enabling it to accommodate the substrate at a low energy cost is selected. There is a price to pay in terms of thermosensibility because the selective pressure is essentially oriented towards the harmonization of the specific activity with ambient thermal conditions. However, as demonstrated by site-directed mutagenesis experiments carried out on the Antarctic subtilisin, the possibility remains to stabilize the structure of these enzymes without affecting their high catalytic efficiency. [less ▲]

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