Promotion of hexagonal phase formation and lipid mixing by fatty acids with varying degrees of unsaturation

Effects of oleic acid and its congeners, elaidic and stearic acids, on the structural properties of phosphatidylethanolamine membranes

“…All samples studied showed a lamellar gel L ␤ phase up to 38 Њ C with an approximately constant repeat distance of 6.4 nm. The similarity observed between gel phases of pure DEPE and DEPE-OA mixtures indicated a complete incorporation of the FA into the lipid bilayer, as previously described (31). DEPE, in the absence of FAs, showed a single L ␣ phase between 38-60 Њ C. From 61 Њ C to 66 Њ C, L ␣ and H II phases coexisted.…”

“…Then, OA effects on PE lipid mesomorphism are most probably due to its molecular structure. Epand et al (31) observed an enhanced ability of OA, with respect to other FAs, for lowering the bilayerto-hexagonal phase temperature at different pHs. Our hypothesis, based on the FA "molecular shape," also explains the ability of OA to facilitate nonlamelar phases from a complementary point of view.…”

Interactions of fatty acids with phosphatidylethanolamine membranes: X-ray diffraction and molecular dynamics studies

“…Thus, at physiological pH, FAs could be partially ionized, although the pKa varies depending upon the environment ( 33,34 ). In previous reports we analyzed the effect of having a net negative charge in 2OHOA and OA within a DEPE matrix, concluding that the extent of FA ionization affected the surface charge density and modulated the number of H-bond interactions in the polar region of the membrane ( 15,39 ). In the present report, the remaining structural features are examined by means of a set of MD trajectories of various DEPE:FA systems simulated in the L ␣ phase.…”

Membrane Structure Modulation, Protein Kinase Cα Activation, and Anticancer Activity of Minerval

“…However, regions rich in PE have special physical properties, such as the nonlamellar-phase propensity, which may result in negative monolayer curvature or even in transient nonlamellar phases. In this context, numerous reports show that the nonlamellar phases, or the propensity to form them, increase the binding to membranes and activity of PKC (Dawson et al, 1984;Epand et al, 1991;Escribá et al, 1995;Giorgione et al, 1995;Mosior et al, 1996;Goñ i and Alonso, 1999). In fact, diacylglycerols activate PKC not only by a direct binding to the Cys-rich C1 domain of the enzyme but also by inducing hexagonal (H II ) phases or increasing the nonlamellar phase propensity of membranes (Dawson et al, 1984;Epand, 1985;Epand and Bottega, 1988;Epand and Lester, 1990;Goldberg et al, 1994;Janes, 1996).…”