Ion-induced changes in head group conformation of lecithin bilayers

Michael F Brown, Joachim Seelig

Research output: Contribution to journalArticle

123 Citations (Scopus)

Abstract

THE structure and orientation of the phosphocholine polar group in lecithin-containing membranes has been discussed extensively. Studies of egg-yolk lecithin and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), using neutron diffraction and 2H and 31P nuclear magnetic resonance (NMR), have led to the conclusion that the phosphocholine dipole is orientated parallel to the membrane surface1-4. On the other hand, 1H and 31P NMR spectra of sonicated DPPC vesicles in the presence of trivalent ions suggested that the choline group is extended approximately perpendicular5 or folded parallel6 to the bilayer surface. We have, therefore, repeated our previous 2H and 31P NMR measurements in the presence of trivalent ions and report here that the addition of these shift reagents induces large changes in the spectral parameters, that is, the 2H quadrupole splittings and the 31P chemical shift anisotropy. These observations can only be interpreted in terms of specific ion-induced changes in the choline head group conformation of DPPC.

Original languageEnglish (US)
Pages (from-to)721-723
Number of pages3
JournalNature
Volume269
Issue number5630
DOIs
StatePublished - 1977
Externally publishedYes

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Lecithins
Conformations
Phosphorylcholine
Nuclear magnetic resonance
Ions
Choline
Magnetic resonance measurement
Membranes
Chemical shift
Neutron diffraction
Crystal orientation
Anisotropy
colfosceril palmitate

ASJC Scopus subject areas

  • General

Cite this

Ion-induced changes in head group conformation of lecithin bilayers. / Brown, Michael F; Seelig, Joachim.

In: Nature, Vol. 269, No. 5630, 1977, p. 721-723.

Research output: Contribution to journalArticle

Brown, Michael F ; Seelig, Joachim. / Ion-induced changes in head group conformation of lecithin bilayers. In: Nature. 1977 ; Vol. 269, No. 5630. pp. 721-723.
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N2 - THE structure and orientation of the phosphocholine polar group in lecithin-containing membranes has been discussed extensively. Studies of egg-yolk lecithin and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), using neutron diffraction and 2H and 31P nuclear magnetic resonance (NMR), have led to the conclusion that the phosphocholine dipole is orientated parallel to the membrane surface1-4. On the other hand, 1H and 31P NMR spectra of sonicated DPPC vesicles in the presence of trivalent ions suggested that the choline group is extended approximately perpendicular5 or folded parallel6 to the bilayer surface. We have, therefore, repeated our previous 2H and 31P NMR measurements in the presence of trivalent ions and report here that the addition of these shift reagents induces large changes in the spectral parameters, that is, the 2H quadrupole splittings and the 31P chemical shift anisotropy. These observations can only be interpreted in terms of specific ion-induced changes in the choline head group conformation of DPPC.

AB - THE structure and orientation of the phosphocholine polar group in lecithin-containing membranes has been discussed extensively. Studies of egg-yolk lecithin and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), using neutron diffraction and 2H and 31P nuclear magnetic resonance (NMR), have led to the conclusion that the phosphocholine dipole is orientated parallel to the membrane surface1-4. On the other hand, 1H and 31P NMR spectra of sonicated DPPC vesicles in the presence of trivalent ions suggested that the choline group is extended approximately perpendicular5 or folded parallel6 to the bilayer surface. We have, therefore, repeated our previous 2H and 31P NMR measurements in the presence of trivalent ions and report here that the addition of these shift reagents induces large changes in the spectral parameters, that is, the 2H quadrupole splittings and the 31P chemical shift anisotropy. These observations can only be interpreted in terms of specific ion-induced changes in the choline head group conformation of DPPC.

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