Luna Lab Publications


Lateral phase separations in binary mixtures of phospholipids having different charges and different crystalline structures

UMMS Affiliation

Department of Cell and Developmental Biology

Publication Date


Document Type



Crystallization; Freeze Fracturing; *Liposomes; Microscopy, Electron; Phosphatidylcholines; Phosphatidylserines; Pulmonary Surfactants; Spin Labels; Thermodynamics


Biochemistry, Biophysics, and Structural Biology | Cell and Developmental Biology


Synthetic dipalmitoyl phosphatidylserine exhibits a sharp chain-melting transition temperature at 51 degrees C as judged by partitioning of the spin label 2,2,6,6-tetramethylpiperidine-1-oxyl. Phase diagrams representing lateral phase separations in binary mixtures of dipalmitoyl phosphatidylserine with dipalmitoyl phosphatidylcholine as well as with dimyristoyl phosphatidylcholine are derived from paramagnetic resonance determinations of 2,2,6,6,-tetramethylpiperidine-1-oxyl partitioning, freeze-fracture electron microscopic studies and theoretical arguments that limit the general form of acceptable phase diagrams. The reported phase diagrams are the first to describe binary mixtures in which one lipid is charged and the second lipid uncharged. These phase diagrams also are the first to include the problem of solid phases with different crystalline conformations as it relates to the occurrence of a pretransition in phosphatidylcholines and its absence in phosphatidylserines. In addition to the phase diagrams reported here for these two binary mixtures, a brief theoretical discussion is given of other possible phase diagrams that may be appropriate to other lipid mixtures with particular consideration given to the problem of crystalline phases of different structures and the possible occurrence of second-order phase transitions in these mixtures.

DOI of Published Version



Biochim Biophys Acta. 1977 Oct 17;470(2):303-16. DOI 10.1016/0005-2736(77)90108-0

Journal/Book/Conference Title

Biochimica et biophysica acta


At the time of publication, Elizabeth Luna was not yet affiliated with the University of Massachusetts Medical School.

Related Resources

Link to Article in PubMed

PubMed ID