References of "Dufour, Samuel"
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See detailThermodynamic Studies Of The Binding Interactions Of Surfactin Analogues To Lipid Vesicles Application Of Isothermal Titration Calorimetry
Razafindralambo, Hary ULg; Dufour, Samuel; Paquot, Michel ULg et al

in Journal of Thermal Analysis and Calorimetry (2009), 95(3), 817-821

Isothermal titration calorimetry was applied for studying the binding interactions of cyclic and linear surfactins with different ionic charge (z= –2 and –3) and lipid chain length (n=14 and 18) to 1 ... [more ▼]

Isothermal titration calorimetry was applied for studying the binding interactions of cyclic and linear surfactins with different ionic charge (z= –2 and –3) and lipid chain length (n=14 and 18) to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC) vesicles in 10mM Tris buffer at pH 8.5 with 150mM NaCl at 25°C. Surfactin analogues interacted spontaneously with POPC vesicles. The binding reactions were endothermic and entropy-driven process. Moreover, significant differences in the binding constant values (K) ranging from 6.6 *10^3 to 9.6* 10^4 M–1 show that cyclic structure and the increase of lipid chain length are favourable on the surfactin binding affinity to POPC vesicles, whereas the rise of the number of negative charges has an opposite effect. [less ▲]

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See detailSurface Properties Of New Virginiamycin M-1 Derivatives
Nott, Katherine ULg; Paquot, Michel ULg; Dufour, Samuel et al

in Colloids and Surfaces B : Biointerfaces (2009), 69(2),

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See detailSurface properties of new virginiamycin M1 derivatives
Nott, Katherine ULg; Paquot, Michel ULg; Dufour, Samuel

in Colloids & Surfaces B : Biointerfaces (2009), 69

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See detailNanoscale membrane activity of surfactins: Influence of geometry, charge and hydrophobicity
Francius, Gregory; Dufour, Samuel; Deleu, Magali ULg et al

in Biochimica et Biophysica Acta - Biomembranes (2008), 1778

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See detailThe iturin and fengycin families of lipopeptides are key factors in antagonism of Bacillus subtilis toward Podosphaera fusca
Romero, D.; de Vicente, A.; Rakotoaly, R. H. et al

in Molecular Plant-Microbe Interactions [=MPMI] (2007), 20(4), 430-440

Podosphaera fusca is the main causal agent of cucurbit powdery mildew in Spain. Four Bacillus subtilis strains, UMAF6614, UMAF6619, UMAF6639, and UMAF8561, with proven ability to suppress the disease on ... [more ▼]

Podosphaera fusca is the main causal agent of cucurbit powdery mildew in Spain. Four Bacillus subtilis strains, UMAF6614, UMAF6619, UMAF6639, and UMAF8561, with proven ability to suppress the disease on melon in detached leaf and seedling assays, were subjected to further analyses to elucidate the mode of action involved in their biocontrol performance. Cell-free supernatants showed antifungal activities very close to those previously reported for vegetative cells. Identification of three lipopeptide antibiotics, surfactin, fengycin, and iturin A or bacillomycin, in butanolic extracts from cell-free culture filtrates of these B. subtilis strains pointed out that antibiosis could be a major factor involved in their biocontrol ability. The strong inhibitory effect of purified lipopeptide fractions corresponding to bacillomycin, fengycin, and iturin A on P fusca conidia germination, as well as the in situ detection of these lipopeptides in bacterial-treated melon leaves, provided interesting evidence of their putative involvement in the antagonistic activity. Those results were definitively supported by site-directed mutagenesis analysis, targeted to suppress the biosynthesis of the different lipopeptides. Taken together, our data have allowed us to conclude that the iturin and fengycin families of lipopeptides have a major role in the antagonism of B. subtilis toward P fusca. [less ▲]

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See detailPenetration of surfactin into phospholipid monolayers: Nanoscale interfacial organization
Eeman, M.; Berquand, A.; Dufrene, Y. F. et al

in Langmuir (2006), 22(26), 11337-11345

Atomic force microscopy (AFM) combined with surface pressure-area isotherms were used to probe the interfacial behavior of phospholipid monolayers following penetration of surfactin, a cyclic lipopeptide ... [more ▼]

Atomic force microscopy (AFM) combined with surface pressure-area isotherms were used to probe the interfacial behavior of phospholipid monolayers following penetration of surfactin, a cyclic lipopeptide produced by Bacillus subtilis strains. Prior to penetration experiments, interfacial behavior of different surfactin molecules (cyclic surfactins with three different aliphatic chain lengths-S13, S14, and S15-and a linear surfactin obtained by chemical cleavage of the cycle of the surfactin S15) has been investigated. A more hydrophobic aliphatic chain induces greater surface-active properties of the lipopeptide. The opening of the peptide ring reduces the surface activity. The effect of phospholipid acyl chain length (dimyristoylphosphatidylcholine, dipalmitoylphosphatidylcholine- (DPPC), and distearoylphosphatidylcholine) and phospholipid polar head (DPPC, dipalmitoylphosphatidylethanolamine and dipalmitoylphosphatidylserine) on monolayer penetration properties of the surfactin S15 has been explored. Results showed that while the lipid monolayer thickness and the presence of electrostatic repulsions from the interfacial film do not significantly influence surfactin insertion, these parameters strongly modulate the ability of the surfactin to alter the nanoscale organization of the lipid films. We also probed the effect of surfactin structure (influence of the aliphatic chain length and of the cyclic structure of the peptide ring) on the behavior of DPPC monolayers. AFM images and isotherms showed that surfactin penetration is promoted by longer lipopeptide chain length and a cyclic polar head. This indicates that hydrophobic interactions are of main importance for the penetration power of surfactin molecules. [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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See detailNovel use of lipopeptide preparations
Deleu, Magali ULg; Brans, Alain; Brasseur, Robert ULg et al

Patent (2004)

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