Landau theory of two-component phospholipid bilayers. I. Phosphatidylcholine/phosphatidylethanolamine mixtures

István P. Sugár, Gianluigi Monticelli

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Priest's phenomenological model (Mol. Cryst. Liq. Cryst. 60 (1980) 167.) on one- and two-component PC bilayers is extended here. We constructed a new excess free energy term in the state function to describe the thermodynamic properties of the two-component phospholipid bilayers where the chain lengths and the polar heads of the components can be different simultaneously. By means of this generalized slate function, we can calculate the phase diagrams of DPPC/DPPE. DMPC/DMPE. DMPC/DPPE. DPPC/DMPE and DSPC/DMPE mixtures. We obtained complete miscibility both in the liquid crystalline and in the gel phase if the chain lengths of the components were the same. If the chain length of the PE component was longer than that of the PC component, we obtained a peritectic system. A eutectic system was obtained in the reverse case. The results of the model were compared with the experimental data available. Applying the quasichemical approximation, we determined the molecular meaning of the phenomenological model parameters. Namely, σ and γ are proportional to the sublimation heat of the CH2 group in the long-chain alkanes and to the hydrogen-bonding energy between the polar heads of the ethanolamines; otherwise the model resulted in - 1.94 kcal/mol per CH2 for the sublimation heat and - 1.4 kcal/mol for the hydrogen-bond energy.

Original languageEnglish
Pages (from-to)281-289
Number of pages9
JournalBiophysical Chemistry
Volume18
Issue number4
DOIs
StatePublished - Nov 1983
Externally publishedYes

Keywords

  • Binary Mixture
  • Phospholipid bilayer: Landau theory
  • Quasichemical approximation: Excess free energy

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