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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology
The Intermediate Monoclinic Phase Of Phosphatidylcholines, Elizabeth Luna, Harden Mcconnell
The Intermediate Monoclinic Phase Of Phosphatidylcholines, Elizabeth Luna, Harden Mcconnell
Elizabeth J. Luna
Two pure phospholipids, dimyristoyl phosphatidylcholine and dipalmitoyl phosphatidylcholine, have been studied using freeze-fracture electron microscopy and the partitioning of the spin label, TEMPO. It is found that the characteristic band pattern, corresponding to monoclinic symmetry in multilamellar liposomes, is observed only in freeze-fracture electron microphotographs when samples are quenched from temperatures intermediate between the chain melting transition temperature and the pretransition temperature of the membrane. Markings are also observed on fracture faces of samples quenched from below the pretransition, but these "bands" are few in number and are widely and irregularly spaced. The lipid membranes used for freeze-fracture were prepared …
Multiple Phase Equilibria In Binary Mixtures Of Phospholipids, Elizabeth Luna, Harden Mcconnell
Multiple Phase Equilibria In Binary Mixtures Of Phospholipids, Elizabeth Luna, Harden Mcconnell
Elizabeth J. Luna
Approximate phse diagrams describing lateral phase separations are given for binary mixtures of dimyristoyl phosphatidylcholine with dipalmitoyl phosphatidylcholine, distearoyl phosphatidycholine, and dipalmitoyl phosphatidylethanolamine. These diagrams are based in part on freeze-fracture electron microscopic data. These phase diagrams represent an improvement over previous studies in that both solid phses (Pbeta' and Lbeta') of the phosphatidylcholines are included. Further consideration is given to the problem of binary mixtures in which there are two Pbeta' phases that do not form a continuous range of solid solutions.