Interactions of divalent cations or basic proteins with phosphatidylethanolamine vesicles

摘要: Small unilamellar vesicles have been prepared from phosphatidylethanolamine by sonication of the lipid in aqueous buffers low ionic strength and high pH. These their interactions with various di- trivalent cations characterized using freeze-fracture electron microscopy. Phosphatidylethanolamine 4 sources was examined: Hens' yolk phosphatidylethanolamine, human grey matter Escherichia coli dimyristoyl phosphatidylethanolamine. The natural formed spherical, uniform 20–40 nm while larger, 70 × 25 nm, disc-shaped when sonicated above phase transition temperature. Fusion egg E. induced dialysis against containing 2.0 nM Ca+ or 3.0 mM Mg2+. fusion resulted precipitation formation multilamellar and, some cases, hexagonal II structures. Dimyristoyl were precipitated at 55°C 1.0 Treatment calcium- magnesium-precipitated hen's EDTA resuspension lipid. specific size shape this manner depends on type ion involved. Dialysis Ca+- Mg2+-precipitated buffer no Ca+, Mg2+ also dissociation precipitate again a new vesicle population. This evidence indicates that are not strongly bound to phosphatidylethanolamine. Egg would fuse presence many ions. Egg beryllium, aluminum, chromium, manganese, cobalt, nickel, copper, zinc, strontium, cadmium, barium, lanthanium, mercury lead. amount required structure resulting found be unique for each ion. Small reacted several basic proteins (cytochrome c, protein myelin, protamine, poly-l-lysine cationically-modified ferritin). initiated but these did phosphatidylcholine nor normal ferritin initiate fusion. Human myelin below