Abstract 159: Eicosapentaenoic Acid and Docosahexaenoic Acid Have Distinct Membrane Locations and Lipid Interactions as Determined by X-ray Diffraction

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) differentially influence lipid oxidation, signal transduction, fluidity, and cholesterol domain formation, potentially due to distinct membrane interactions. We used small angle x-ray diffraction to test EPA and DHA effects on model membrane structure. Vesicles were prepared to model human peripheral cell membranes using 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol (C) (0.3 C:POPC mole ratio), and treated with vehicle, EPA, or DHA (1:10 mole ratio to POPC). Membrane width (d-space) was 59.5 A at 10°C, decreasing to 54.7 A at 30°C due to increased acyl chain dynamics. EPA or DHA had no effect on membrane d-space (<1 A change). Electron density profiles from diffraction data were superimposed on corresponding vehicle profiles (Fig. 1). EPA increased membrane hydrocarbon core electron density over a broad area, up to ± 20 A from the membrane center, indicating an energetically favorable extended membrane orientation for EPA...