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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 sensor with Polydimethylsiloxane membrane and CMOS potentiostat for wide-range glucose measurements.
Mross, Stefan; Fuerst, Peter; Pierrat, Sebastien et al

in IEEE Sensors Journal (2015), 15(12), 7096-7104

We report on an electrochemical measurement setup comprising a glucose sensor and a CMOS potentiostat with a two-layer membrane as the first steps toward the development of an integrated in-situ sensor ... [more ▼]

We report on an electrochemical measurement setup comprising a glucose sensor and a CMOS potentiostat with a two-layer membrane as the first steps toward the development of an integrated in-situ sensor system for bioreactors. The potentiostat has a chip size of 2.1 mm× 2.5 mm and a linear current range from −220 nA to 240 nA with a linearity of R2 = 0.9995. For wide range measurements of glucose concentrations in cell culture media, electrodes functionalized with the enzyme glucose oxidase were spin-coated with membranes made from polydimethylsiloxane (PDMS). A two-stage curing scheme of the PDMS was applied, and different membrane thicknesses and curing times were evaluated. With these membranes, glucose concentrations up to 500 mM were measured with a linear measurement range up to 200 mM. The sensors were successfully employed in the glucose monitoring of a culture of Saccharomyces cerevisiae to monitor the glucose consumption of the cells. For interference elimination, the cellulose acetate membranes were employed. [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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See detailLes enzymes hydrolytiques du système digestif chez les crustacés pagurides
Arnould, Chantal; Jeuniaux, Charles ULg

in Cahiers de Biologie Marine (1982), 23

The enzymatic activity of 23 different types of hydrolases (oligosaccharidases, polysaccharidases, esterases, proteases) was detected and located in the digestive system of 6 species of hermit-crabs ... [more ▼]

The enzymatic activity of 23 different types of hydrolases (oligosaccharidases, polysaccharidases, esterases, proteases) was detected and located in the digestive system of 6 species of hermit-crabs (Crustacea Dacapoda Pagurioidea), using mainly histoenzymological methods. These hydrolases are secreted at different levels of the alimentary canal, not only in the digestive gland ("hepatopancreas"), but also in the gastric and intestinal epithelia. [less ▲]

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See detailEnzymes in animal feed.
Rossi, Florence; Thewis, André ULg

in Fifteenth Forum for Applied Biotechnology (2001)

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See detailEnzymes involved in wall peptide crosslinking in Escherichia coli K12, strain 44
Nguyen-Distèche, Martine ULg; Ghuysen, Jean-Marie ULg; Pollock, Jerry J. et al

in European Journal of Biochemistry (1974), 41(3), 447-455

By using the glutamate-amidated tetrapeptide l-alanyl-d-isoglutaminyl-(l)-meso-diamino-pimelyl-(l)-d-alanine as a probe, there appears to exist in the membranes of Escherichia coli K12 strain 44 a dd ... [more ▼]

By using the glutamate-amidated tetrapeptide l-alanyl-d-isoglutaminyl-(l)-meso-diamino-pimelyl-(l)-d-alanine as a probe, there appears to exist in the membranes of Escherichia coli K12 strain 44 a dd-carboxypoptidase-transpeptidase system which does not recognize this peptide and a dd-carboxypoptidase-transpeptidase system which recognizes it. The dd-carboxypeptidase-endopeptidase system is essentially hydrolytic. It catalyzes the hydrolysis of UDP-N-acetyl-muramyl-pentapeptide into UDP-N-acetylmuramyl-tetrapeptide and the hydrolysis of the wall peptidoglycan peptide dimer into monomers. These activities are not inhibited by the glutamate-amidated tetrapeptide. The system may consist either of two enzyme proteins having predominantly carboxypeptidase activity and endopeptidase activity, respectively, or of one enzyme protein of which the functioning would depend upon the environmental conditions. The dd-carboxypeptidase-transpeptidase system (a) catalyzes concomitant hydrolysis (carboxypeptidase activity) and transfer (natural model transpeptidase activity) reactions with the pentapeptide l-alanyl-γ-d-glutamyl-(l)-meso-diaminopimelyl-(l)-d-alanyl-d-alanine. The transfer reaction leads to the synthesis of a dimer that is identical to the one which occurs in the E. coli wall peptidoglycan; (b) utilizes the glutamate-amidated tetrapeptide as an acceptor. Simultaneous exposure of the pentapeptide and the glutamate-amidated tetrapeptide to the enzyme system leads to the formation of an hybrid monoamidated peptide dimer and causes a decreased hydrolysis of the pentapeptide; (c) by virtue of its own carboxypeptidase activity, it appears to exert some endopeptidase activity. Both carboxypeptidase and endopeptidase activities of this system are inhibited by the glutamate-amidated tetrapeptide, but this represents only a small fraction of the total hydrolytic activity of the membrane Brij-36T extract. (d) The system catalyzes an unnatural model transpeptidation reaction in which glycine replaces d-alanine at the C-terminal position of the nucleotide UDP-N-acetylmuramyl-pentapeptide. This system may also consist either of two enzyme proteins having predominantly natural model transpeptidase activity and unnatural model transpeptidase activity, respectively, or of one enzyme protein of which the functioning would depend upon the environmental conditions. Whatever the exact situation, the E. colidd-carboxypeptidase-transpeptidase system is in many respects, similar to the dd-carboxy-peptidase-transpeptidase single polypeptide enzymes isolated from Streptomyces strains R39 and R61. [less ▲]

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See detailEnzymes that degrade bacterial cell walls
Ghuysen, Jean-Marie ULg; Tipper, Donald J.; Strominger, Jack L.

in Methods in Enzymology (1966), 8

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See detailLes enzymes: produits de la biotechnologie pour l'agro-alimentaire.
Thonart, Philippe ULg; Hubert, J. B.; Rikir, R. et al

in Annales de Gembloux (1989), 95

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See detailEOF analysis of long-term reconstructed AVHRR Pathfinder SST in the South China Sea
Huynh, Thi Hong Ngu ULg; Alvera Azcarate, Aïda ULg; Barth, Alexander ULg et al

Poster (2014, May 02)

Sea surface temperature (SST) is one of the key variables often used to investigate ocean dynamics, ocean-atmosphere interaction, and climate change. For recent decades, the AVHRR Pathfinder SST, measured ... [more ▼]

Sea surface temperature (SST) is one of the key variables often used to investigate ocean dynamics, ocean-atmosphere interaction, and climate change. For recent decades, the AVHRR Pathfinder SST, measured by infrared sensors, has been widely used because of its high resolution and long time-series. The disadvantage of the AVHRR Pathfinder SST is high percentage of missing data due to cloud coverage. This becomes more serious in the South China Sea (SCS) because it is located in the tropical region, frequently covered by clouds. In this study, we used the Data INterpolating Empirical Orthogonal Functions (DINEOF) method to reconstruct daily night-time 4 km AVHRR Pathfinder SST spanning from 1989 to 2009 for the whole SCS. In order to better understand the spatial and temporal variability of the SCS SST, an EOF analysis of the reconstructed field is performed in association with surface wind. The first SST mode, accounting for 69% of the variance, presents the cooling (warming) of the basin due to the solar inclination through seasons, water exchange, topography, and monsoon-induced cyclonic circulation. The second SST mode, explaining 24.8% of the variance, shows the advection of cold and warm water from two opposite directions along the southwest-northeast diagonal of the basin. The second SST mode is affected by the atmospheric anticyclone (cyclone) located over the Philippine Sea. Comparing both SST modes with Nino3.0 index, it shows that the interannual variability of the SCS SST is influenced by the moderate and strong ENSO events with a lag of 5-6 months. Moreover, the analysis of the high-resolution reconstructed dataset reveals some oceanic features that could not be captured in previous EOF analyses. [less ▲]

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See detailEOF analysis of Sea Surface Temperature in the Canary Island - Madeira region
Troupin, Charles ULg; Alvera Azcarate, Aïda ULg; Barth, Alexander ULg et al

Conference (2011, April 05)

We analyzed Sea Surface Temperature (SST) images in a region covering the Canary Islands and Madeira archipelagos, with the following objectives 1. The reconstruction of incomplete SST satellite images ... [more ▼]

We analyzed Sea Surface Temperature (SST) images in a region covering the Canary Islands and Madeira archipelagos, with the following objectives 1. The reconstruction of incomplete SST satellite images during the year 2009. 2. The determination of the main spatial and temporal patters in the region. SST images for 2009 are downloaded from the Medspiration project (http://www.medspiration.org). The images consist of combined measurements from several satellite systems. The images with less than 5% of valid pixels (e.g., clouds) were removed, so that out of the 365 initial images, 347 were kept. The method used in this work for the reconstruction of missing data is Data INterpolating Empirical Orthogonal Functions (DINEOF, Alvera-Azcárate et al., 2005). The results show that the first mode is largely dominant, with 87% of the variance explained, and represents the regional seasonal cycle. The second mode accounts for 9% of the variance and depicts a separation between coastal waters and open-ocean waters. The signal of the Cape Ghir upwelling filament is also present in the second mode. The reconstruction allows one to reproduce the characteristic mesoscale features of the region: the coastal upwelling, the island wakes (Gran Canaria, Madeira, ... ), the filament and the eddies in the lee of the main islands. A near-operational version of the reconstruction has been implemented and is available at http://gher-diva.phys.ulg.ac.be/DINEOF/dineof_allCAN.html [less ▲]

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