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Structure and mechanical properties of giant lipid (DMPC) vesicle bilayers from 20 degrees C below to 10 degrees C above the liquid crystal-crystalline phase transition at 24 degrees C.

Publication ,  Journal Article
Needham, D; Evans, E
Published in: Biochemistry
October 1988

We have used micromechanical tests to measure the thermoelastic properties of the liquid and gel phases of dimyristoylphosphatidylcholine (DMPC). We have found that the rippled P beta' phase is only formed when a vesicle is cooled to temperatures below the main acyl chain crystallization transition, Tc, under zero or very low membrane tension. We also found that the P beta' surface ripple or superlattice can be pulled flat under high membrane tension into a planar structure. For a ripple structure formed by acyl chains perpendicular to the projected plane, the projected area change that results from a flattening process is a direct measure of the molecular crystal angle. As such, the crystal angle was found to increase from about 24 degrees just below Tc to about 33 degrees below the pretransition. It was also observed that the P beta' superlattice did not form when annealed L beta' phase vesicles were heated from 5 degrees C to Tc; likewise, ripples did not form when the membrane was held under large tension during freezing from the L alpha phase. Each of these three procedures could be used to create a metastable planar structure which we have termed L*beta' since it is lamellar and plane-crystalline with acyl chains tilted to the bilayer plane. However, we show that this structure is not as condensed as the L beta' phase below 10 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

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Published In

Biochemistry

DOI

EISSN

1520-4995

ISSN

0006-2960

Publication Date

October 1988

Volume

27

Issue

21

Start / End Page

8261 / 8269

Related Subject Headings

  • Thermodynamics
  • Molecular Conformation
  • Models, Theoretical
  • Mathematics
  • Lipid Bilayers
  • Elasticity
  • Dimyristoylphosphatidylcholine
  • Crystallization
  • Biochemistry & Molecular Biology
  • 3404 Medicinal and biomolecular chemistry
 
Journal cover image

Published In

Biochemistry

DOI

EISSN

1520-4995

ISSN

0006-2960

Publication Date

October 1988

Volume

27

Issue

21

Start / End Page

8261 / 8269

Related Subject Headings

  • Thermodynamics
  • Molecular Conformation
  • Models, Theoretical
  • Mathematics
  • Lipid Bilayers
  • Elasticity
  • Dimyristoylphosphatidylcholine
  • Crystallization
  • Biochemistry & Molecular Biology
  • 3404 Medicinal and biomolecular chemistry