title: Phase transition behaviour of artificial liposomes composed of phosphatidylcholines acylated with cyclopropane fatty acids.
abstract: Phase transitions of liposomes composed of synthetic phoshatidylcholines acylated with the cyclopropane fatty acids, lactobacillic and dihydrosterculic acid, were studied by differential scanning calorimetry. Transition temperatures were approx. 16 degrees C higher than for phosphatidylcholines acylated with the corresponding unsaturated fatty acids, cis-vaccenic and oleic acid. Though our transition temperatures were all several degrees lower than those determined by Silvius and McElhaney ((1979) Chem. Phys. Lipids 25, 125--134), the increase produced by replacement of the double bond with a cyclopropane ring was the same. We propose that this replacement, through its effect on membrane fluidity, may serve to regulate the activity of membrane-associated processes such as transport.
mesh_terms: D000215:Acylation; D055598:Chemical Phenomena; D002621:Chemistry; D003521:Cyclopropanes / Q000494:pharmacology*; D005227:Fatty Acids / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated; D008081:Liposomes / Q000378:metabolism*; D008560:Membrane Fluidity / Q000187:drug effects*; D010713:Phosphatidylcholines / Q000378:metabolism*; D013696:Temperature
chemical_list: D003521:Cyclopropanes; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008081:Liposomes; D010713:Phosphatidylcholines; C028775:cyclopropane fatty acids; C029355:dihydrosterculic acid; C028716:phytomonic acid