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Neutron and X-ray diffraction structural analysis of phosphatidylinositol bilayers.

Publication ,  Journal Article
McDaniel, RV; McIntosh, TJ
Published in: Biochim Biophys Acta
August 7, 1989

Phosphatidylinositol (PI) bilayers, squeezed together by applied osmotic pressures, were studied by both neutron diffraction and X-ray diffraction. The lamellar repeat period for PI bilayers decreased from 9.5 nm at an applied pressure of 1.1.10(6) dyn/cm2 (1.1 atm) to 5.4 nm at an applied pressure of 1.6.10(7) dyn/cm2 (16 atm). Further increases in applied pressure, up to 2.7.10(9) dyn/cm2 (2700 atm) reduced the repeat period by only about 0.3 nm, to 5.1 nm. Thus, a plot of applied pressure versus repeat period shows a sharp upward break for repeat periods less than about 5.4 nm. For repeat periods of less than 5.4 nm, analysis of neutron-scattering density profiles and electron-density profiles indicates that the structure of the PI bilayers changes as the bilayers are dehydrated, even though there are only small changes in the repeat period. These structural changes are most likely due to removal of water from the headgroup regions of the bilayer. D2O/H2O exchange experiments show that, at an applied pressure of 2.8.10(7) dyn/cm2, water is located between adjacent PI headgroups in the plane of the bilayer. We conclude that, although electrostatics provide the dominant long-range repulsive interaction, hydration repulsion and steric hindrance between PI headgroups from apposing bilayers provide the major barriers for the close approach of adjacent PI bilayers for repeat periods less than 5.4 nm. This structural analysis also indicates that the phosphoinositol group extends from the plane of the bilayer into the fluid space between adjacent bilayers. This extended orientation for the headgroup is consistent with electrophoretic measurements on PI vesicles.

Duke Scholars

Published In

Biochim Biophys Acta

DOI

ISSN

0006-3002

Publication Date

August 7, 1989

Volume

983

Issue

2

Start / End Page

241 / 246

Location

Netherlands

Related Subject Headings

  • X-Ray Diffraction
  • Water
  • Structure-Activity Relationship
  • Phosphatidylinositols
  • Osmotic Pressure
  • Neutrons
  • Molecular Structure
  • Lipid Bilayers
  • Deuterium
  • Cattle
 

Citation

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McDaniel, R. V., & McIntosh, T. J. (1989). Neutron and X-ray diffraction structural analysis of phosphatidylinositol bilayers. Biochim Biophys Acta, 983(2), 241–246. https://doi.org/10.1016/0005-2736(89)90239-3
McDaniel, R. V., and T. J. McIntosh. “Neutron and X-ray diffraction structural analysis of phosphatidylinositol bilayers.Biochim Biophys Acta 983, no. 2 (August 7, 1989): 241–46. https://doi.org/10.1016/0005-2736(89)90239-3.
McDaniel RV, McIntosh TJ. Neutron and X-ray diffraction structural analysis of phosphatidylinositol bilayers. Biochim Biophys Acta. 1989 Aug 7;983(2):241–6.
McDaniel, R. V., and T. J. McIntosh. “Neutron and X-ray diffraction structural analysis of phosphatidylinositol bilayers.Biochim Biophys Acta, vol. 983, no. 2, Aug. 1989, pp. 241–46. Pubmed, doi:10.1016/0005-2736(89)90239-3.
McDaniel RV, McIntosh TJ. Neutron and X-ray diffraction structural analysis of phosphatidylinositol bilayers. Biochim Biophys Acta. 1989 Aug 7;983(2):241–246.

Published In

Biochim Biophys Acta

DOI

ISSN

0006-3002

Publication Date

August 7, 1989

Volume

983

Issue

2

Start / End Page

241 / 246

Location

Netherlands

Related Subject Headings

  • X-Ray Diffraction
  • Water
  • Structure-Activity Relationship
  • Phosphatidylinositols
  • Osmotic Pressure
  • Neutrons
  • Molecular Structure
  • Lipid Bilayers
  • Deuterium
  • Cattle