Stability and Liquid-Liquid Phase Separation in Mixed Saturated Lipid Bilayers

The phase stability of a fluid lipid bilayer composed of a mixture of DC18PC, (DSPC), and a shorter DCns PC, with ns from 8 to 17, has been studied using a self-consistent field theory that explicitly includes molecular details and configurational properties of the lipid molecules. Phase separation...

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Veröffentlicht in:Biophysical journal 2009-05, Vol.96 (10), p.3977-3986
Hauptverfasser: Longo, Gabriel S., Schick, M., Szleifer, I.
Format: Artikel
Sprache:eng
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Zusammenfassung:The phase stability of a fluid lipid bilayer composed of a mixture of DC18PC, (DSPC), and a shorter DCns PC, with ns from 8 to 17, has been studied using a self-consistent field theory that explicitly includes molecular details and configurational properties of the lipid molecules. Phase separation between two liquid phases was found when there was a sufficient mismatch between the hydrophobic thicknesses of the two bilayers composed entirely of one component or the other. This occurs when ns ≤ 12 and there is a sufficient concentration of the shorter lipid. The mixture separates into a thin bilayer depleted of DSPC and a thick bilayer enriched in DSPC. Even when there is no phase separation, as in the cases when there is either insufficient concentration of a sufficiently short lipid or any concentration of a lipid with ns > 12, we observe that the effect of the shorter lipid is to increase the susceptibility of the system to fluctuations in the concentration. This is of interest, given that a common motif for the anchoring of proteins to the plasma membrane is via a myristoyl chain, that is, one with 14 carbons.
ISSN:0006-3495
1542-0086
DOI:10.1016/j.bpj.2009.02.043