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See detailLipase from Yarrowia lipolytica.
Destain, Jacqueline ULg; Weber, D.; Thonart, Philippe ULg

in Mededelingen van de Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen (Rijksuniversiteit te Gent) (1997), 62(4a),

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See detailLipase production by Yarrowia lipolytica: study of the effects of operating conditions by factorial design of experiments
Lopes, M.; Gomes, I.; Araújo, C. et al

in European Symposium on Biochemical Engineering Science : book of abstracts”. [S.l. : s.n. 2006] (2006, August)

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See detailLipase production in Yarrowia lipolytica overproducing mutants.
Fickers, P.; Nicaud, J. M.; Destain, Jacqueline ULg et al

Poster (2002, July)

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See detailLipase synthesis of fatty acid sugar esters in pure ionic liquids
Galonde, Nadine ULg

Poster (2010, October 14)

Sugar fatty acid esters are broadly consumed in many commercial applications and their synthesis gained a considerable interest since they are biodegradable, tasteless, odorless, non-toxic and non ... [more ▼]

Sugar fatty acid esters are broadly consumed in many commercial applications and their synthesis gained a considerable interest since they are biodegradable, tasteless, odorless, non-toxic and non-irritant. Ionic liquids are organic salts entirely comprised of ions with a melting point below 100°C. This new category of solvent may allow the enzymatic synthesis of sugar fatty acid ester to go toward a “greener” process. Within the purpose of using “green” systems for synthesis of glycosylated compounds, studies on the use of ionic liquids to obtain fatty acid sugar esters with carbohydrates coming from lignocellulosic material as substrates was carried out. The enzymatic synthesis of mannose myristate ionic liquids as enzymatic medium and the yield obtained will be presented in our poster. [less ▲]

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See detailLipase-assisted synthesis of potential bio-based surfactants starting from lignocellulosic carbohydrates
Richard, Gaetan ULg; Nott, Katherine ULg; Paquot, Michel ULg et al

Poster (2010, April)

Surfactants constitute an important class of compounds with a lot of applications, especially in the food and beverage industries (emulsion forming and stabilization, antiadhesive and antimicrobial ... [more ▼]

Surfactants constitute an important class of compounds with a lot of applications, especially in the food and beverage industries (emulsion forming and stabilization, antiadhesive and antimicrobial activities)1. With the prospect of synthesising new active compounds, white biotechnology offers efficient tools. Indeed, the use of enzymes as biocatalysts provides an interesting synthetic route in comparison to the chemical way that often requires high reaction temperatures and suffers from a lack of specificity, resulting in complex mixtures. Among all the biocatalysts available, lipases represent a class of industrial interest 2,3. In parallel, the starting material is also an important parameter : due to the depletion of petroleum reserves, its ever increasing price and various environmental aspects, the use of renewable or biomass resources is inevitable. Within the frame of a biorefinery project, we focused on the lipase-assisted modification of uronic acids. These carbohydrates can be obtained from lignocellulosic material, and, in the presence of fatty alcohols, the Candida antarctica lipase B catalyses the synthesis of amphiphilic compounds. Owing to the initial conditions used and the addition of co-solvents, we optimized the synthesis of these bio-based potential surfactants, and obtained a panel of various structures depending to the acyl acceptor used. The poster will present the details of these syntheses. [less ▲]

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See detailLipase-catalyzed interesterification of butterfat with rapeseed oil: new approaches for the monitoring of the reaction.
Hanon, Emilien ULg; Aguedo, Mario ULg; Danthine, Sabine ULg et al

Poster (2007)

Butterfat (BF) is one main source of diet fats. However, it has been less and less well perceived due to its poor spreadability when refrigerated and cholesterol and saturated fatty acids, promoters of ... [more ▼]

Butterfat (BF) is one main source of diet fats. However, it has been less and less well perceived due to its poor spreadability when refrigerated and cholesterol and saturated fatty acids, promoters of coronary heart diseases. Thus, consumer’s demand for healthy palatable fat spreads with good development of modified butter-based spreads. One ordinary method used by manufacturers for such modifications is enzymatic interesterification of a lipase to restructure triacylglycerides (TAG), i.e. to induce the exchange of fatty acid residues amongst glycerol backbones. This leads to changes in TAG species and in physical properties of the fat, namely in solid fat content (SFC) and in melting profile. Rapeseed oil (RO) contains a large amount of oleic acid and has significant contents of linoleic and linolenic acids, i.e. a high global content of unsaturation-rich residues. Thus, EIE of BF with RO may bring nutritional improvements to the reaction product, when compared to BF alone. The EIE of BF and canola oil (a low-erucic acid RO) catalyzed by the immobilized sn-1,3 specific Rhizopus arrhizus lipase in solvent-free batch and micro-aqueous systems, was previously studied. The aim of the present study was first to assess the evolution of chemical, physical and thermal modifications occurring during solvent-free batch EIE of BF and RO, with the use of lipozyme TL IM. The evolution of TAG profiles, interesterification degree, dropping point, solid fat content and free fatty acids was monitored during the reaction, especially during the first hours. Differential scanning calorimetry was also applied to follow the formed product. Then the establishment of relations between the DP and differential scanning calorimetry data and the interesterification degree was emphasized. [less ▲]

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See detailLipase-catalyzed synthesis of L-cysteine glucosyl esters in organic media
Valepyn, Emmanuel ULg; Nys, Joël ULg; Richel, Aurore ULg et al

in Biocatalysis & Biotransformation (2011), 29(1), 25-30

New sugar amino acids were synthesized by enzymatic esterification of D -glucose with L -cysteine using immobilized lipase B from Candida antarctica in a mixed solvent system composed of 2-methyl-2 ... [more ▼]

New sugar amino acids were synthesized by enzymatic esterification of D -glucose with L -cysteine using immobilized lipase B from Candida antarctica in a mixed solvent system composed of 2-methyl-2-butanol and dimethyl sulfoxide. Addition of small quantities of water to the medium improved the glucose conversion yield by a factor of two. [less ▲]

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See detailLIPASES FROM PSYCHROTROPHIC ANTARCTIC BACTERIA
Feller, Georges ULg; Thiry, M.; Arpigny, J. L. et al

in FEMS Microbiology Letters (1990), 66(1-3), 239-243

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See detailLes lipases sont des hydrolases atypiques : principales caractéristiques et applications
Fickers, Patrick ULg; Destain, Jacqueline ULg; Thonart, Philippe ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2008), 12(2), 119-130

Due to their kinetic and substrate specificities, triacylglycerol acyl-hydrolases or lipases are atypical enzymes. In function of their microenvironment, lipases are able to act as hydrolases in aqueous ... [more ▼]

Due to their kinetic and substrate specificities, triacylglycerol acyl-hydrolases or lipases are atypical enzymes. In function of their microenvironment, lipases are able to act as hydrolases in aqueous solution or as biocatalysts in organic synthesis. As hydrolases, they are responsible of the triglycerids catabolism into fatty acids and glycerol. In many organisms, this reaction plays a major role in the fat and lipid metabolism. In addition, lipases are also able to hydrolyse phospholipids and cholesterol esters. In organic solvent, lipases could catalyse reactions such as esterifications, acidolysis or alcoolysis with enantio-, regio- and chimioselectivity. Lipases form a mixed class of enzyme due to their animal, vegetal or microbial origins. All those properties led to the development of many applications in the food and chemical industries but also in the medical and therapeutic field. [less ▲]

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See detailLipid and oxylipin profile during storage of potato tubers
Fauconnier, Marie-Laure ULg; Welti, R.; Delaplace, Pierre ULg et al

Poster (2004, June 01)

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See detailLipid and oxylipin profile during storage of potato tubers
Fauconnier, Marie-Laure ULg; Welti, R.; Delaplace, Pierre ULg et al

Poster (2004, June 03)

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See detailLipid And Oxylipin Profiles During Aging And Sprout Development In Potato Tubers (Solanum Tuberosum L.)
Fauconnier, Marie-Laure ULg; Welti, R.; Blee, E. et al

in Biochimica et Biophysica Acta-Molecular and Cell Biology of Lipids (2003), 1633(2),

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See detailLipid and Protein Composition of the Mammary Tumour Virus and the Milk Fat-Globule Membrane Isolated from the milk of infected Mice
Calberg-Bacq, C. M.; François, C.; Gosselin, L. et al

in Biochemical Society Transactions (1975)

Milk fat globule membranes and mammary tumour virus particles have been obtained from the milk of a swiss albino mice strain. Comparative biochemistry shows that these two structures differ significantly ... [more ▼]

Milk fat globule membranes and mammary tumour virus particles have been obtained from the milk of a swiss albino mice strain. Comparative biochemistry shows that these two structures differ significantly in the phospholipid, polypeptide and glycopeptide patterns and enzymatic activities. However, the lipid profile and the morphology of both structures suggest a filiation with the plasma membrane. Density fractions obtained from the crude virus preparation have been thoroughly investigated. The results sugget that most of these fractions represent degraded virus and/or atipycal virus assembly. [less ▲]

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See detailLIPID INTERACTION PROPERTIES OF NOVEL RHAMNOLIPIDS
Nasir, Mehmet Nail ULg; Crowet, Jean-Marc ULg; Lins, Laurence ULg et al

Conference (2013, November)

Biosurfactants which are surface active molecules produced by micro-organisms present a wide structural diversity (glycolipids, lipoaminoacids, lipopeptides, polymers,...) and numerous advantages compared ... [more ▼]

Biosurfactants which are surface active molecules produced by micro-organisms present a wide structural diversity (glycolipids, lipoaminoacids, lipopeptides, polymers,...) and numerous advantages compared to their chemically synthesized counterparts. Among glycolipids, rhamnolipids which are secondary metabolites produced mainly by strains of Pseudomonas aeruginosa, 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 recognized 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. In our laboratory, new rhamnolipids with various chain lengths and with or without a terminal carboxylic acid function were obtained via the development of a synthesis procedure consisting of two biocatalyzed steps involving naringinase and lipase [5]. The objective of this work was to investigate their interaction with model membranes in relation with their structure in order to give insight about the mechanism of their biological action. A range of complementary experimental and modelling methods was used to analyze their interaction with membrane models. Results reveal differential interaction with lipids according to the structure of the rhamnolipid. The nature of the lipid is also a key parameter for the ınteractions. [less ▲]

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See detailThe lipid phosphatase SHIP2 controls insulin sensitivity
Clément, S.; Krause, U.; Desmedt, F. et al

in Nature (2001), 409

Insulin is the primary hormone involved in glucose homeostasis, and impairment of insulin action and/or secretion has a critical role in the pathogenesis of diabetes mellitus. Type-II SH2-domain ... [more ▼]

Insulin is the primary hormone involved in glucose homeostasis, and impairment of insulin action and/or secretion has a critical role in the pathogenesis of diabetes mellitus. Type-II SH2-domain-containing inositol 5-phosphatase, or 'SHIP2', is a member of the inositol polyphosphate 5-phosphatase family. In vitro studies have shown that SHIP2, in response to stimulation by numerous growth factors and insulin, is closely linked to signalling events mediated by both phosphoinositide-3-OH kinase and Ras/mitogen-activated protein kinase. Here we report the generation of mice lacking the SHIP2 gene. Loss of SHIP2 leads to increased sensitivity to insulin, which is characterized by severe neonatal hypoglycaemia, deregulated expression of the genes involved in gluconeogenesis, and perinatal death. Adult mice that are heterozygous for the SHIP2 mutation have increased glucose tolerance and insulin sensitivity associated with an increased recruitment of the GLUT4 glucose transporter and increased glycogen synthesis in skeletal muscles. Our results show that SHIP2 is a potent negative regulator of insulin signalling and insulin sensitivity in vivo [less ▲]

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See detailLipid raft targeting of hematopoietic protein tyrosine phosphatase by protein kinase C theta-mediated phosphorylation.
Nika, Konstantina; Charvet, Celine; Williams, Scott et al

in Molecular & Cellular Biology (2006), 26(5), 1806-16

Protein kinase C theta (PKC theta) is unique among PKC isozymes in its translocation to the center of the immune synapse in T cells and its unique downstream signaling. Here we show that the hematopoietic ... [more ▼]

Protein kinase C theta (PKC theta) is unique among PKC isozymes in its translocation to the center of the immune synapse in T cells and its unique downstream signaling. Here we show that the hematopoietic protein tyrosine phosphatase (HePTP) also accumulates in the immune synapse in a PKC theta-dependent manner upon antigen recognition by T cells and is phosphorylated by PKC theta at Ser-225, which is required for lipid raft translocation. Immune synapse translocation was completely absent in antigen-specific T cells from PKC theta-/- mice. In intact T cells, HePTP-S225A enhanced T-cell receptor (TCR)-induced NFAT/AP-1 transactivation, while the acidic substitution mutant was as efficient as wild-type HePTP. We conclude that HePTP is phosphorylated in the immune synapse by PKC theta and thereby targeted to lipid rafts to temper TCR signaling. This represents a novel mechanism for the active immune synapse recruitment and activation of a phosphatase in TCR signaling. [less ▲]

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See detailLipid storage metabolism is limited by the prevailing low oxygen concentrations within developing seeds of oilseed rape.
Vigeolas, Hélène ULg; van Dongen, Joost T; Waldeck, Peter et al

in Plant Physiology (2003), 133(4), 2048-60

The aim of this study was to investigate whether endogenous restrictions in oxygen supply are limiting for storage metabolism in developing oilseed rape (Brassica napus) seeds. Siliques were studied 30 d ... [more ▼]

The aim of this study was to investigate whether endogenous restrictions in oxygen supply are limiting for storage metabolism in developing oilseed rape (Brassica napus) seeds. Siliques were studied 30 d after flowering, when rapid lipid accumulation is occurring in the seeds. (a). By using microsensors, oxygen concentrations were measured within seeds and in the silique space between seeds. At ambient external oxygen (21% [v/v]) in the light, oxygen fell to 17% (v/v) between and 0.8% (v/v) within seeds. A step-wise reduction of the external oxygen concentration led within 2 h to a further decrease of internal oxygen concentrations, and a step-wise increase of the external oxygen concentration up to 60% (v/v) resulted in an increase in internal oxygen that rose to 30% (v/v) between and 8% (v/v) within seeds. (b). The increase in oxygen levels in the seeds was accompanied by a progressive increase in the levels of ATP, UTP, and the ATP to ADP and UTP to UDP ratios over the entire range from 0% to 60% (v/v) external oxygen. (c). To investigate metabolic fluxes in planta, 14C-sucrose was injected into seeds, which remained otherwise intact within their siliques. The increase in oxygen in the seeds was accompanied by a progressive increase in the rate of lipid (including triacylglycerol), protein and cell wall synthesis, and an increase in glycolytic flux over a range from sub- to superambient oxygen concentrations. In contrast to lipid synthesis, starch synthesis was not significantly increased at superambient oxygen levels. The levels of fermentation products such as lactate and glycerol-3P increased only at very low (0%-4% [v/v]) external oxygen concentrations. (d). When 14C-acetate or 14C-acetyl-coenzyme A (CoA) was injected into seeds, label incorporation into triacylglycerol progressively increased over the whole range of external oxygen concentrations from 0% to 60% (v/v). (e). Stimulation of lipid synthesis was accompanied by an increase in sugar levels and a decrease in the levels of hexose-phosphates and acetyl-CoA, indicating sucrose unloading and the use of acetyl-CoA as possible regulatory sites. (f). Increased lipid synthesis was also accompanied by an increase in the maximal activities of invertase and diacylglycerol acyltransferase. (g). The developmental shift from starch to lipid storage between 15 and 45 d after flowering was accompanied by an increase in the seed energy state. (h). The results show that at ambient oxygen levels, the oxygen supply is strongly limiting for energy metabolism and biosynthetic fluxes in growing rape seeds, affecting lipid synthesis more strongly than starch synthesis. The underlying mechanisms and implications for strategies to increase yield and storage product composition in oilseed crops are discussed. [less ▲]

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See detailLipid-binding properties of synthetic peptide fragments of human apolipoprotein A-II.
Benetollo, C.; Lambert, Géraldine ULg; Talussot, C. et al

in European Journal of Biochemistry (1996), 242(3), 657-64

Human apolipoprotein A-II (apo A-II) consists of three potential amphipathic helices of 17 residues each, which contribute to the lipid-binding properties of this apolipoprotein. The conformation and ... [more ▼]

Human apolipoprotein A-II (apo A-II) consists of three potential amphipathic helices of 17 residues each, which contribute to the lipid-binding properties of this apolipoprotein. The conformation and lipid-binding properties of these peptides, either as single-helix or as two-helix peptides, were investigated by turbidity, fluorescence, electron-microscopy and circular-dichroism measurements, and are compared in this article. The lipid affinity of shorter C-terminal segments of apo A-II was compared with those of the single-helix or two-helix peptides, to define the minimal peptide length required for stable complex formation. The properties of the apo-A-II-(13-48)-peptide were further compared with those of the same segment after deletion of the Ser31 and Pro32 residues, because the deleted apo-A-II-(13-30)-(33-48)-peptide, is predicted to form a long uninterrupted helix. The single helices of apo A-II could not form stable complexes with phospholipids, and the helix-turn-helix segment spanning residues 13-48 was not active either. The apo-A-II-(37-77)-peptide and the apo-A-II-(40-73)-peptide could form complexes with lipids, which appear as discoidal particles by negative-staining electron microscopy. The shortest C-terminal domain of apo A-II able to associate with lipids to form stable complexes was the apo-A-II-(40-73)-peptide, which consisted of the C-terminal helix, a beta-turn and part of the preceding helix. The shorter apo-A-II-(49-77)-peptide, and the helical apo-A-II-(13-30)-(33-48)-peptide, could also associate with phospholipids. The complexes formed were, however, less stable, as they dissociated outside the transition temperature range of the phospholipid. These data suggest that the C-terminal pair of helices of apo A-II, which is the most hydrophobic pair, is responsible for the lipid-binding properties of the entire protein. The N-terminal pair of helices of apo A-II at residues 13-48 does not associate tightly with lipids. The degree of internal similarity and the cooperativity between the helical segments of apo A-II is thus less pronounced than in apo A-I or apo A-IV. The N-terminal and C-terminal domains of apo A-II appear to behave as two distinct entities with regard to lipid-protein association. [less ▲]

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