Steric repulsion between phosphatidylcholine bilayers.

Journal Article

The change in pressure needed to bring egg phosphatidylcholine bilayers into contact from their equilibrium separation in excess water has been determined as a function of both distance between the bilayers and water content. A distinct upward break in the pressure-distance relation appears at an interbilayer separation of about 5 A, whereas no such deviation is present in the pressure-water content relation. Thus, this break is not a property of the dehydration process per se, but instead is attributed to steric repulsion between the mobile lipid head groups that extend 2-3 A into the fluid space between bilayers. That is, electron density profiles of these bilayers indicate that the observed break in the pressure-spacing relation occurs at a bilayer separation where extended head groups from apposing bilayers come into steric hindrance. The pressure-spacing data are used to separate steric pressure from the repulsive hydration pressure, as well as to quantitate the range and magnitude of the steric interaction. An appreciable fraction of the measured steric energy can be ascribed to a decrease in configurational entropy due to restricted head-group motion as adjacent bilayers come together.

Full Text

Duke Authors

Cited Authors

  • McIntosh, TJ; Magid, AD; Simon, SA

Published Date

  • November 17, 1987

Published In

Volume / Issue

  • 26 / 23

Start / End Page

  • 7325 - 7332

PubMed ID

  • 3427075

International Standard Serial Number (ISSN)

  • 0006-2960

Language

  • eng

Conference Location

  • United States