Interfacial organisation and phase behavior of mixed galactolipid-DPPC-phytosterol assemblies at the air-water interface and in hydrated mesophases

Kergomard Jeanne, Carrière Frédéric, Paboeuf Gilles, Artzner Franck, Barouh Nathalie, Bourlieu Claire, Vié Véronique. 2022. Interfacial organisation and phase behavior of mixed galactolipid-DPPC-phytosterol assemblies at the air-water interface and in hydrated mesophases. Colloids and Surfaces. B, Biointerfaces, 217:112646, 10 p.

https://doi.org/10.1016/j.colsurfb.2022.112646

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Résumé : The structural behavior of model assemblies composed of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), the two main galactolipids found in plants, was investigated at the air/water interface and in aqueous dispersion. To approach the composition of the natural photosynthetic membranes, tunable Langmuir model membrane of galactolipids (GL) were used, and were complexified to form either heterogenous binary or ternary assemblies of GL, phospholipids (PL), and phytosterols (pS). The impact of pS, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or both on the structural properties of GL membrane was studied. The nature of the interactions between the different molecules was investigated using biophysical characterizations (ellipsometry, tensiometry, atomic force microscopy). In addition, the phase behavior was determined by SAXS analysis on the model assemblies in aqueous dispersions. Results revealed the good interfacial stability of these specific plant membrane lipids. The morphology of the GL film was characteristic of a fluid phase, with an interfacial roughness induced by the intercalation of monogalactosyl and digalactosyl polar heads of MGDG and DGDG, respectively. A phase heterogeneity in the monolayer was induced by the addition of DPPC and/or pS, which resulted in the modification of galactolipid organization and headgroup interactions. These structural changes were confirmed by SAXS analysis, showing more favorable interactions between MGDG and DPPC than between DGDG and DPPC in aqueous dispersion. This phenomenon was exacerbated in the presence of pS.

Mots-clés Agrovoc : membrane, membrane cellulaire, plante, propriété physicochimique, lipide, phytostérol, surfactant, expérimentation en laboratoire

Mots-clés complémentaires : galactolipides

Mots-clés libres : Galactolipids, Phytosterol, Natural surfactant, Vegetal photosynthetic assemblies

Classification Agris : F50 - Anatomie et morphologie des plantes

Champ stratégique Cirad : CTS 1 (2019-) - Biodiversité

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