Headgroup Interactions in Mixed Phospholipid Bilayers

2H NMR methods have been used to study how bilayer-forming phospholipids interact with each other at the membrane surface. Aqueous dispersions of dimyristoyl-sn-phosphatidylcholine (Myr2-PtdCho), dimyristoyl-sn-phosphatidylethanolamine (Myr2-PtdEtn), and dimyristoyl-sn-phosphatidyl-3-glycerol, speci...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 80; no. 6; pp. 1613 - 1615
Main Authors Sixl, Frank, Watts, Anthony
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences of the United States of America 01.03.1983
National Acad Sciences
Subjects
Amplitude
Biochemistry
Biological Sciences: Biophysics
Biophysical Phenomena
Biophysics
Deuterium
Functional groups
Hydrogen
Lipid Bilayers
Lipids
Magnetic Resonance Spectroscopy
Membrane Lipids
P branes
Phospholipids
Quadrupoles
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Summary:2H NMR methods have been used to study how bilayer-forming phospholipids interact with each other at the membrane surface. Aqueous dispersions of dimyristoyl-sn-phosphatidylcholine (Myr2-PtdCho), dimyristoyl-sn-phosphatidylethanolamine (Myr2-PtdEtn), and dimyristoyl-sn-phosphatidyl-3-glycerol, specifically deuterated at different positions in their headgroups, give well-resolved2H NMR powder spectra. These spectra are characteristic of a lipid bilayer with quadrupole splittings that are sensitive to the amplitude of headgroup motion. In binary mixed bilayers of deuterated lipids with an unlabeled component, all parts of the deuterated headgroup monitor the presence of the second lipid from changes in the measured quadrupole splittings. The headgroups of the charged lipids, dimyristoyl-sn-phosphatidylserine and dimyristoyl-sn-phosphatidyl-3-glycerol, interact to the largest extent with the choline moiety of Myr2-PtdCho and the ethanolamine moiety of Myr2-PtdEtn, whereas a somewhat smaller but still marked alteration in headgroup motion was observed in Myr2-PtdCho/Myr2-PtdEtn mixtures. The large changes in the deuterium quadrupole splittings for the zwitterionic lipids after addition of a charged lipid suggest that either a strong perturbation in the hydrogen bonding occurs or changes take place in the water structure at the membrane surface, or possibly both.
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ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.80.6.1613