Biophysical properties of unusual phospholipids and sterols from marine invertebrates

Liposomes composed of 1,2-di-(5Z,9Z)-5-9-hexacosadienoyl-sn-glycero-3-pho sph ocholine underwent an endothermic phase transition at 42 degrees C. Cholesterol or the marine sterols studied did not affect this transition to an appreciable extent, but rather were excluded from the phospholipid bilayers. Membranes composed of 1,2-di-(5Z,9Z)-5,9-hexacosadienoyl-sn-glycero-3-pho sph ocholine displayed very similar phase properties. Effects of the marine sterols on dipalmitoylphosphatidylcholine bilayers were also investigated.