References of "Wathelet, Bernard"
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See detailEffect Of Extraction Conditions On The Yield, Purity And Surface Properties Of Sugar Beet Pulp Pectin Extracts
Yapo, Marcel Beda; Robert, Christelle; Etienne, Isabelle et al

in Food Chemistry (2007), 100(4), 1356-1364

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See detailEffects of the stage of maturation and varieties on the chemical composition of banana and plantain peels
Happi Emaga, Thomas ULg; Andrianaivo, Rado; Wathelet, Bernard ULg et al

in Food Chemistry (2007), 103(2), 590-600

A study of the chemical composition of six varieties of fruit peels of the banana and plantain: dessert banana (Musa AAA), plantain (Musa AAB) cooking banana (Musa ABB) and hybrid (Musa AAAB) at three ... [more ▼]

A study of the chemical composition of six varieties of fruit peels of the banana and plantain: dessert banana (Musa AAA), plantain (Musa AAB) cooking banana (Musa ABB) and hybrid (Musa AAAB) at three stages of ripeness, was carried out in order to explore their potential applications. The varieties did not affect chemical constituents in a consistent manner. Peel of the six varieties was rich in total dietary fibre (TDF) (40-50%). The protein content in peel of the banana and plantain was 8-11%. Leucine, valine, phenylalanine and threonine were essential amino acids in significant quantities: Lysine was the limiting amino acid. The content of lipid varied from 2.2% to 10.9% and was rich in polyunsaturated fatty acids, particularly linoleic acid and alpha-linolenic acid. Potassium was the most significant mineral element. Peel of plantain was richer in starch than were the banana peels. Maturation of fruits involved increase in soluble sugar content and, at the same time, decrease in starch. The degradation of the starch under the action of the endogenous enzymes, may explain the increase in the soluble sugar content. Further investigations on the composition and the physiological functions (using animal-feeding experiments) of these dietary fibres must be considered. (c) 2006 Elsevier Ltd. All rights reserved. [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 detailPotential Of Local Agricultural By-Products For The Rearing Of African Catfish Clarias Gariepinus In Rwanda: Effects On Growth, Feed Utilization And Body Composition
Nyina-Wamwiza, Laeticia; Wathelet, Bernard ULg; Kestemont, Patrick

in Aquaculture Research (2007), 38(2),

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See detailEffect of extraction conditions on the yield and purity of apple pomace pectin precipitated but not washed by alcohol
Garna, Haikel; Mabon, Nicolas; Robert, Christelle et al

in Journal of Food Science (2007), 72(1), 1-9

A study of the influence of extraction condition (pH: 1.5 to 2; temperature: 80 to 90 degrees C; extraction time: 1 to 3 h), on the yield and purity of apple pomace pectin without elimination of ... [more ▼]

A study of the influence of extraction condition (pH: 1.5 to 2; temperature: 80 to 90 degrees C; extraction time: 1 to 3 h), on the yield and purity of apple pomace pectin without elimination of impurities by alcohol washing was carried out. The alcohol precipitate yields varied from 2.9% to 8.9% depending on the pH. At pH 1.5, these yields were higher than those obtained at pH 2 contrary to the galacturonic acid purity (%w/w). Compounds other than pectins were solubilized from the cell walls of apple pomace at pH 1.5, and they were precipitated with alcohol. The apple pectins obtained from the different extraction procedures were highly methylated (54.5% to 79.5%), especially when the conditions (temperature, pH) were drastic. Similar conclusions can be drawn for the neutral sugar content that decreased at pH 1.5 (arabinose, xylose, and galactose) or at the highest temperatures and extraction times (arabinose and galactose). The phenomenon of demethylation and pectin degradation of neutral sugars chains can be observed at acid pH, and long extraction times. The presence of high quantities of mannose or fructose, glucose, and xylose in the alcohol precipitate showed that pectin precipitation with ethanol was not specific. [less ▲]

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See detailIsolation And Chemical Evaluation Of Carob (Ceratonia Siliqua L.) Seed Germ
Dakia, Patrick; Wathelet, Bernard ULg; Paquot, Michel ULg

in Food Chemistry (2007), 102(4),

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See detailUse of a Plackett-Burman experimental design to examine the impact of extraction parameters on yields and compositions of pectins extracted from chicory roots (Chicorium intybus L.)
Robert, Christelle; Devillers, Thierry; Wathelet, Bernard ULg et al

in Journal of Agricultural and Food Chemistry (2006), 54(19), 7167-7174

Chicory root pectin was isolated by acid extraction followed by alcohol precipitation. Because the extraction conditions have important effects on the features of pectins, an experimental design was used ... [more ▼]

Chicory root pectin was isolated by acid extraction followed by alcohol precipitation. Because the extraction conditions have important effects on the features of pectins, an experimental design was used to study the influence of 17 different extraction parameters on yield and composition of pectin: pH, temperature, time of extraction, solid/liquid ratio, and different pretreatments of the pulps before extraction. Twenty extractions were conducted and examined for their significance on yield and sugar content using the Plackett-Burman factorial design. The acid extraction of chicory roots resulted in an average yield of 11% containing 86% of sugars. It was found that extraction temperature, time, protease pretreatment, water purity, and water washing of pulps significantly affected yield and pectin composition with an increase of yield and purity of pectin in harsher extraction conditions. [less ▲]

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See detailKinetic of the hydrolysis of pectin galacturonic acid chains and quantification by ionic chromatography
Garna, H.; Mabon, N.; Nott, Katherine ULg et al

in Food Chemistry (2006), 96(3), 477-484

These experiments were designed to develop a rapid, repeatable and accurate analysis method for the quantification of galacturonic acid of pectins. Different pectin hydrolysis procedures (chemical and ... [more ▼]

These experiments were designed to develop a rapid, repeatable and accurate analysis method for the quantification of galacturonic acid of pectins. Different pectin hydrolysis procedures (chemical and enzymatic) were carried out with H2SO4, TFA and HCl at different acid concentrations (0.2, 1 and 2 M) and temperatures (80 and 100 degrees C). Enzymatic and combined chemical and enzymatic hydrolysis of pectin were also studied. A acid hydrolysis under drastic conditions (100 degrees C) is insufficient for complete hydrolysis and results in low recovery of galacturonic acid residues. Mild chemical hydrolysis (0.2, 1 and 2 M H2SO4 72 h at 80 degrees C) is also insufficient for complete depolymerization. Its main advantage is cleavage of the galacturonic acid chains into oligomeric forms without any degradation within 72 h of hydrolysis. However, enzymatic hydrolysis with VL9 for 2 h at 50 degrees C and combined chemical and enzymatic hydrolysis (0.2 M TFA at 80 degrees C for 72 h and VL9) give high recovery of this acid. Analysis of the liberated sugar residue by HPAEC allows us to determine the galacturonic acid composition of this polysaccharide accurately with high selectivity and sensitivity in one assay without the need for derivatization. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailMaintenance threonine requirement and efficiency of its use for accretion of whole-body threonine and protein in Atlantic salmon (Salmo salar L.) fry.
Rollin, Xavier; Wauters, Jean*-Baptiste; Bodin, Noe Lie et al

in British Journal of Nutrition (2006), 95(2), 234-45

Eighteen groups of seventy Atlantic salmon (Salmo salar L.) fry (initial mean body weight 0.8 (sd 0.01) g) were fed on semi-purified diets containing graded levels of l-threonine (Thr) in 15 litres ... [more ▼]

Eighteen groups of seventy Atlantic salmon (Salmo salar L.) fry (initial mean body weight 0.8 (sd 0.01) g) were fed on semi-purified diets containing graded levels of l-threonine (Thr) in 15 litres aquaria at a temperature of 14.5+/-1 degrees C. Doses of Thr represented 1, 31, 41, 51, 62, 72, 83 and 93 % of its ideal level for optimum protein deposition. Indispensable amino acids other than Thr were included in the same proportion (on a g/16 g N basis) as in the Atlantic salmon fry whole-body carcass. Following 36 d of feeding and a 36 h fast, fry were killed for whole-body protein and amino acid analysis. Weight gain (r2 0.98), protein accretion (r2 0.97), and Thr accretion (r2 0.97) were linear (P<0.01) functions of Thr intake. Slope of the Thr accretion regression line showed that the efficiency of Thr utilisation above maintenance was 76 %. At zero Thr intake, fry lost 5.4 mg Thr/kg body weight0.75 per d. The Thr maintenance requirement was 7.2 mg/kg body weight0.75 per d and the Thr requirement for growth was 66 mg for 1 g protein deposition. Increasing doses of Thr resulted in increased (P<0.05) concentrations of histidine and lysine, and decreased concentrations of isoleucine in whole-body protein. The maintenance need for Thr represented 13.4 % of the total need for Thr. The data suggest that efficiency of Thr utilisation above maintenance is constant at all levels of Thr intake between 1 and 93 % of the level required for optimum protein deposition. [less ▲]

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See detailStrategy for the qualitative and quantitative analysis of crop syrup containing enzymatically produced Isomaltooligosaccharides known as emerging prebiotics.
Goffin, Dorothée ULg; Blecker, Christophe ULg; Wathelet, Bernard ULg et al

Poster (2006)

Isomaltooligosaccharides (IMOs) are non-digestible oligosaccharides, considered as prebiotics and therefore aim to selectively feed probiotics indigenous to the human colon. Recent data obtained in human ... [more ▼]

Isomaltooligosaccharides (IMOs) are non-digestible oligosaccharides, considered as prebiotics and therefore aim to selectively feed probiotics indigenous to the human colon. Recent data obtained in human subjects, support the involvement of dietary oligosaccharides in physiological processes in the different intestinal cell type and also outside the gastrointestinal tract (e.g. hormone production, lipid and carbohydrate metabolism). IMOs consists of glucose monomers linked by at least one α-1-6, or in a lower proportion α -1-3 (nigerose family) or α -1-2 (kojibiose family) glucosidic linkages. In our case they are produced enzymatically from corn starch. It results in a very complex mixture with molecules characterized at the same time by their DP value (from 2 to ~20), linkages types (α-1-2, 3 or 6) and the proportion and position of each type of linkage (only α -1-6 or combined types). The challenge of this study was to find a qualitative and quantitative method to characterize the syrups. In a subsequent study, every unidentified peak could be determined by NMR or Mass spectrometry. Three different chromatographic methods have been tested and compared over their selectivity, sensibility, robustness, applicability and their quantitative power. The HPLC-RID (Refractive Index Detector) used with a Prevail Carbohydrate column (Alltech), adapted for carbohydrates with a certain value of DP, appear to be poorly selective due to the obligation of working in isocratic conditions. The HPLC-ELSD (Evaporating Light Scattering Detector) used with the same column gave a very good separation upon the DP as the Prevail accepts a wide range of solvant changing and even a separation of the different DP 2 molecules. The sensibility was also improved due to the stability of the baseline. The quantitative analysis is a bit more awkward due to the relatively limited linear portion of the calibration curve. High-performance Anion Exchange Chromatography coupled with Pulsed Amperometric Detection (HPAEC-PAD) appeared to deserve a special mention, since it provides selective separation and sensitive detection. In fact, this technique is the only chromatographic one to separate with effectiveness homologue molecules having a difference only in their DP (up to high DPs) or linkage types. This is due to the separation mode based on the difference in ionic force of the sugars in alkaline conditions (mainly due to the DP and the structure of the molecule). However, during the detection, the electrochemical behavior of carbohydrates can be affected by molecular weight as well as by structural differences giving rise to different response factors; as a consequence, HPAEC-PAD is not generally considered as suitable for quantitative studies of complex mixtures of oligosaccharides. In this work a methodological approach is presented in order to get a quantitative response through a rigorous methodology for our IMOs. It also opens the way to the theoretical determination of the response factor for the homologue molecules in relation with their structure and DP. [less ▲]

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See detailStrategy for the qualitative and quantitative analysis of crop syrup containing enzymatically produced Isomaltooligosaccharides known as emerging prebiotics
Goffin, Dorothée ULg; Blecker, Christophe ULg; Wathelet, Bernard ULg et al

Poster (2006)

Isomaltooligosaccharides (IMOs) are non-digestible oligosaccharides, considered as prebiotics and therefore aim to selectively feed probiotics indigenous to the human colon. Recent data obtained in human ... [more ▼]

Isomaltooligosaccharides (IMOs) are non-digestible oligosaccharides, considered as prebiotics and therefore aim to selectively feed probiotics indigenous to the human colon. Recent data obtained in human subjects, support the involvement of dietary oligosaccharides in physiological processes in the different intestinal cell type and also outside the gastrointestinal tract (e.g. hormone production, lipid and carbohydrate metabolism). IMOs consists of glucose monomers linked by at least one α-1-6, or in a lower proportion α -1-3 (nigerose family) or α -1-2 (kojibiose family) glucosidic linkages. In our case they are produced enzymatically from corn starch. It results in a very complex mixture with molecules characterized at the same time by their DP value (from 2 to ~20), linkages types (α-1-2, 3 or 6) and the proportion and position of each type of linkage (only α -1-6 or combined types). The challenge of this study was to find a qualitative and quantitative method to characterize the syrups. In a subsequent study, every unidentified peak could be determined by NMR or Mass spectrometry. Three different chromatographic methods have been tested and compared over their selectivity, sensibility, robustness, applicability and their quantitative power. The HPLC-RID (Refractive Index Detector) used with a Prevail Carbohydrate column (Alltech), adapted for carbohydrates with a certain value of DP, appear to be poorly selective due to the obligation of working in isocratic conditions. The HPLC-ELSD (Evaporating Light Scattering Detector) used with the same column gave a very good separation upon the DP as the Prevail accepts a wide range of solvant changing and even a separation of the different DP 2 molecules. The sensibility was also improved due to the stability of the baseline. The quantitative analysis is a bit more awkward due to the relatively limited linear portion of the calibration curve. High-performance Anion Exchange Chromatography coupled with Pulsed Amperometric Detection (HPAEC-PAD) appeared to deserve a special mention, since it provides selective separation and sensitive detection. In fact, this technique is the only chromatographic one to separate with effectiveness homologue molecules having a difference only in their DP (up to high DPs) or linkage types. This is due to the separation mode based on the difference in ionic force of the sugars in alkaline conditions (mainly due to the DP and the structure of the molecule). However, during the detection, the electrochemical behavior of carbohydrates can be affected by molecular weight as well as by structural differences giving rise to different response factors; as a consequence, HPAEC-PAD is not generally considered as suitable for quantitative studies of complex mixtures of oligosaccharides. In this work a methodological approach is presented in order to get a quantitative response through a rigorous methodology for our IMOs. It also opens the way to the theoretical determination of the response factor for the homologue molecules in relation with their structure and DP. [less ▲]

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See detailUsing lupin seeds to replace soybean meal in pig feed: effect of alpha-galactosidase supplement and lupin variety on nitrogen retention and diet digestibility in pigs.
Froidmont, E.; Wathelet, Bernard ULg; Beckers, Yves ULg et al

in Mexico, where old and new world lupins meet. Proceedings of the 11thInternational Lupin Conference, Guadalajara, Jalisco, Mexico, 4-9 May2005 (2006)

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See detailSynthese enzymatique d’esters de sucre au départ d’huiles végétales
Detry, J.; Destain, Jacqueline ULg; Lognay, Georges ULg et al

Poster (2005, October 14)

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See detailSugar esters lipase mediated synthesis from vegetable oils
Destain, Jacqueline ULg; Detry, Jean; Lognay, Georges ULg et al

Scientific conference (2005, September 19)

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See detailSugar esters lipase mediated synthesis from vegetable oils
Destain, Jacqueline ULg; Detry, J.; Lognay, Georges ULg et al

Poster (2005, September)

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See detailMycosubtilin overproduction by Bacillus subtilis BBG100 enhances the organism's antagonistic and biocontrol activities
Leclère, Valérie; Béchet, Max; Adam, Akram et al

in Applied and Environmental Microbiology (2005), 71(8), 4577-4584

A Bacillus subtilis derivative was obtained from strain ATCC 6633 by replacement of the native promoter (if he mycosubtilin operon by a constitutive promoter originating from the replication gene repU of ... [more ▼]

A Bacillus subtilis derivative was obtained from strain ATCC 6633 by replacement of the native promoter (if he mycosubtilin operon by a constitutive promoter originating from the replication gene repU of the Staphylococcus aureus plasmid pUB110. The recombinant strain, designated BBG100, produced up to 15-fold more mycosubtilin than the wild type produced. The overproducing phenotype was related to enhancement of the antagonistic activities against several yeasts and pathogenic fungi. Hemolytic activities were also clearly increased in the modified strain. Mass spectrometry analyses of enriched mycosubtilin extracts showed similar patterns of lipopeptides for BBG100 and the wild type. Interestingly, these analyses also revealed a new form of mycosubtilin which was more easily detected in the BBG100 sample. When tested for its biocontrol potential, wild-type strain ATCC 6633 was almost ineffective for reducing a Pythium infection of tomato seedlings. However, treatment of seeds with the BBG100 overproducing strain resulted in a marked increase in the germination rate of seeds. This protective effect afforded by mycosubtilin overproduction was also visualized by the significantly greater fresh weight of emerging seedlings treated with BBG100 compared to controls or seedlings inoculated with the wild-type strain. [less ▲]

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See detailImprovement of lupin seed valorisation by the pig with the addition of alpha-galactosidase in the feed and the choice of a suited variety.
Froidmont, E.; Wathelet, Bernard ULg; Beckers, Yves ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2005), 9(4), 225-235

Three experiments were conducted to assess whether an a-galactosidase supplement improved the utilisation of lupin seeds by growing and finishing pigs and to determine the best lupin variety in presence ... [more ▼]

Three experiments were conducted to assess whether an a-galactosidase supplement improved the utilisation of lupin seeds by growing and finishing pigs and to determine the best lupin variety in presence of a-galactosidase. In experiment 1, three iso-nitrogen (iso-N) and iso-net energy (iso-NE) diets containing 15% of soybean meal (SBM diet) or 20% of lupin seeds (Lupinus albus var. Arès), with or without an a-galactosidase supplement (‘lupin’ and ‘lupin + a-gal’ diets, respectively), were ingested by 12 pigs fitted with a caecal canula, following a completely randomized experimental design. The ileal digestibility of a-galactosides tended to increase with the lupin + a-gal diet. Nitrogen retention of pigs eating the SBM diet was similar to that of those fed with the lupin + a-gal diet and higher than that observed for pigs given the lupin diet. The results suggested that a-galactosides are the main anti-nutritional factors in lupin seeds for pigs. The same diets were investigated in a production trial (experiment 2) involving 48 pigs with a live weight of between 30 and 105 kg. The fattening period was similar for the SBM and lupin + a-gal diets (107 d) and longer for the lupin diet (123 d). With the lupin diet there was a lower average daily gain (ADG, -16%) and a higher food conversion ratio (FCR, + 8%) than with the two other diets. The backfat of pigs fed with lupin-based diets contained fewer polyunsaturated fatty acids (PUFA) and had a lower w6/w3 ratio. In experiment 3, three iso-N and iso-NE diets containing different varieties of lupin (Lupinus albus cv Lublanc and Amiga; Lupinus angustifolius cv Boltensia) and an a-galactosidase supplement were investigated in 12 pigs fitted with a caecal canula, as in Exp. 1. The results showed that the digestible protein supply by the Boltensia diet was higher than in the others. However, the Boltensia variety led to a higher urinary N excretion than the Lublanc variety. The results obtained with Amiga were intermediate. Consequently, the utilisation of ingested and digested proteins was relatively high with the Lublanc diet, intermediate with the Amiga diet and low with the Boltensia diet. The results suggested that the Lublanc variety was better adapted for pig feed that contained an a-galactosidase supplement. [less ▲]

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See detailHemolytic activity of new linear surfactin analogs in relation to their physico-chemical properties
Dufour, Samuel; Deleu, Magali ULg; Nott, Katherine ULg et al

in Biochimica et Biophysica Acta - General Subjects (2005), 1726

New linear analogs of surfactin have been synthesized. Their physico-chemical parameters were determined. The results indicate that these linear products show surface activities although they are lowered ... [more ▼]

New linear analogs of surfactin have been synthesized. Their physico-chemical parameters were determined. The results indicate that these linear products show surface activities although they are lowered compared to those of cyclic compounds. The hemolytic activities have also been assayed. In contrast with cyclic surfactins, no significant hemolysis occurs for the linear products in the range of concentrations tested. Moreover, a protective effect against Triton X-100 induced hemolysis has been highlighted for linear surfactins. The concentration at which this protective effect happens is correlated directly to the CMC, and inversely to the acyl chain length of the product. In a hypotonic medium, analogs having a long acyl chain tend to increase the hemolysis, meanwhile the product with the shortest chain tends to decrease it. [less ▲]

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See detailHemolytic activity of new linear surfactin analogs
Dufour, Samuel; Deleu, Magali ULg; Wathelet, Bernard ULg et al

Poster (2005)

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See detailA Chemoselective Ligation For The Synthesis Of Amino Acid Derivatives Of Virginiamycin M-1
Nott, Katherine ULg; Dufour, Samuel; Gossele, Francis et al

in Tetrahedron Letters (2005), 46(43),

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