Time Resolved X-Ray Diffraction Measurements of Phosphatidylcholine-Phosphatidylethanolamine: Effect of Phosphatidylethanolamine Acyl Chain Length

Beth Cunningham, Illinois Wesleyan University
W. Tamura-Lis
L.J. Lis
P.J. Quinn

Abstract

Phase transitions in 1:1 molar mixtures of DLPE:DPPC, DMPE:DPPC, DPPE:DPPC, and DSPE: DPPC have been examined using time-resolved X-ray diffraction techniques. A model of the gel-to-liquid crystal phase transition observed upon heating for these lipid mixtures in which the mixing of domains of gel and liquid crystal phase lipids is the rate-limiting step can be formulated. Upon cooling, it is inferred that small domains of gel state lipid are nucleated from the Lα phase. The miscibility of components and domains is also related to the types of proposed phase diagrams.