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

Interfacial adsorption and activity of pancreatic lipase-related protein 2 onto heterogeneous plant lipid model membranes

“…The previous characterization study of homogeneous and heterogeneous GL monolayers has indeed shown that the addition of DPPC and pS to a GL monolayer led to the formation of condensed phase domains enriched in DPPC and MGDG, reducing the lateral distance between the acyl chains available for gPLRP2 to insert (Kergomard, Carrière, Paboeuf, Artzner, et al, 2022). This higher packing could thus explain the lag phase observed before the gPLRP2 could reach its optimum activity, a high packing density at the air/water interface having been proposed to explain the long induction times observed for other lipases onto tightly packed short-chained phospholipids (Verger et al, 1973) and diacylglycerols (Wieloch et al, 1982) monolayers.…”

“…The GL/DPPC/pS system showed a coexistence of condensed liquid/expanded liquid phases, with the presence of condensed phase domains visible on the AFM images, enriched in DPPC-MGDG and pS (Figure 1.B). Additionally, the presence of pS in condensed domains have induced the appearance of defects, that could modulate the subsequent adsorption of lipolytic enzymes (Bourlieu et al, 2016;Kergomard, Carrière, Paboeuf, Artzner, et al, 2022). For the MGDG/DGDG/SQDG/PG biomimetic monolayer (Figure 1.C), small flower-shaped nanodomains of 1.6 ± 0.1 nm height were evidenced at the air/water interface, coexisting with a fluid phase.…”

Modulation of gastric lipase adsorption onto mixed galactolipid-phospholipid films by addition of phytosterols

“…Ternary and quaternary mixtures of GL, DPPC and pS, namely GL/DPPC (50:50, mol/mol) and GL/DPPC/pS (45:45:10 mol/mol/mol), respectively, were also prepared to mimic the composition of natural vegetal membrane (see Table 1 for relative molar composition). Lipid-lipid interactions and molecular organization at the air/water interface of the three monolayers studied are reported in Kergomard et al (2022). 10…”

“…The AFM images of the interface were compared before and after the rDGL injection to highlight the distribution of the enzyme in the GL films and to determine the reorganization of the monolayers induced by the lipid-protein interactions. Details on AFM study on GL mixed films in the absence of rDGL are reported in Kergomard et al (2022).…”

“…The inclusion of phytosterols in the GL/DPPC mixture has been shown to generate defects at the level of the condensed phase, due to the preferential interactions between the phytosterols and the saturated fatty acids (Kergomard et al (2022)). The AFM images Figure 4.B revealed that 2h after the injection of rDGL into the subphase, a regular protein network has formed onto the fluid phase.…”