Ca 2+ induced phase separations in phospholipid mixtures

• Published in: Chemistry and physics of lipids Vol. 39; no. 1; pp. 119 - 124
• Main Authors: Tamura-Lis, W., Reber, E.J., Cunningham, B.A., Collins, J.M., Lis, L.J.
• Format: Journal Article
• Language: English
• Published: Elsevier Ireland Ltd 1986
• Subjects: Me 2+-induced phase separation; phosphatidylcholine; phosphatidylethanolamine; phospholipid multilamellar arrays; X-ray diffraction; phosphatidylethanolamine; phosphatidylcholine; EYPC; X-ray diffraction; Me 2+-induced phase separation; EYPE; DLPC; DMPC; DOPC; phospholipid multilamellar arrays
• ISSN: 0009-3084; 1873-2941
• DOI: 10.1016/0009-3084(86)90105-2

We have probed the character of the observed phase separation in mixtures of phosphatidylcholines (PC) and/or phosphatidylethanolamines (PE) in the presence of CaCl 2 solutions. Egg yolk phosphatidylethanolamine (EYPE) and a 1:1 molar ratio of dioleoylphosphatidylcholine/dioleoylphosphatidylethanolamine (DOPC/DOPE) were observed to undergo phase separation in CaCl 2 solutions, as was previously observed for egg yolk phosphatidylcholine (EYPC) (L.J. Lis et al. Biochemistry, 20 (1981) 1771–1777). However, the mixed chain lipid, palmitoyloleoyl-PC, yielded only a single phase in water or CaCl 2 solution. We hypothesize that two lipid species are necessary for the observed phase separation to occur, but that the separation itself is not a function of the individual lipid species, but of the mixture.