Lateral order in binary lipid alloys and its coupling to membrane functions

W. Knoll, G. Schmidt, H. Rötzer, T. Henkel, W. Pfeiffer, E. Sackmann, S. Mittler-Neher, J. Spinke

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

Densitometry, Raman spectroscopy and small angle neutron scattering are employed to elucidate the miscibility behaviour of lipid mixtures organized as liposomal dispersions. First, temperature-composition-phase diagrams for several binary alloys of dialkyl-lecithins differing in chain lengths by an inceasing number of CH2-groups are derived. A mixture of dimyristoyllecithin and distearoyllecithin (ΔCH2=4) shows a peritectic phase behaviour with a miscibility gap in the gel state. In the fluid phase, at high enough temperatures, homogeneous mixtures of the two components are formed at all molar ratios. However, upon approaching a critical point by either lowering the temperature or increasing the hydrostatic pressure, critical concentration fluctuations are observed. If one component of a binary mixture in charged, electrostatic interactions can be used to induce phase separation at constant temperature. This is demonstrated for Ca2+-driven demixing in alloys of lecithin and negatively charged phosphatidylglycerol. The influence of the various concepts for the induction of lateral structure formation in lipid membranes on integral functional units like ionophores is demostrated by analysing the single channel current fluctuations of gramicidin in bimolecular lipid membranes. Ca2+, as well as polyelectrolyte- induced phase separations are shown and discussed as examples for the important (lateral) order-function relatioinship in biomembranes.

Original languageEnglish
Pages (from-to)363-374
Number of pages12
JournalChemistry and Physics of Lipids
Volume57
Issue number2-3
DOIs
StatePublished - Mar 1991
Externally publishedYes

Keywords

  • binary phase diagrams
  • chemically driven phase separation
  • lipid mixtures
  • order-function relationship
  • single channel current fluctuations

Fingerprint

Dive into the research topics of 'Lateral order in binary lipid alloys and its coupling to membrane functions'. Together they form a unique fingerprint.

Cite this