A microscopic model for lipid/protein bilayers with critical mixing
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A statistical mechanical lattice model is proposed to describe the phase diagram of phospholipid bilayers with small transmembrane proteins or polypeptides. The model is based on the extended Pink-Green-Chapman model (Zhang et al. (1992) Phys. Rev. A 45, 7560-7567) for pure lipid bilayers which undergo a first-order gel-fluid phase transition. The interaction between the lipid bilayer and the protein or polypeptide is modelled using the concept of hydrophobic matching. The phase diagram has been derived by computer-simulation techniques which fully account for thermal density fluctuations and which operate on the level of the free-energy thereby permitting an accurate identification of the phase boundaries. The calculations predict a closed loop of gel-fluid coexistence with a lower critical mixing point. Specific-heat traces across the phase diagram are also presented. The theoretical results for the phase diagram, the specific-heat function, and the transition enthalpy are related to recent experimental measurements on phospholipid bilayers mixed with synthetic transmembrane amphiphilic polypeptides or with gramicidin A.
Originalsprog | Engelsk |
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Tidsskrift | Biochimica et Biophysica Acta - Biomembranes |
Vol/bind | 1147 |
Udgave nummer | 1 |
Sider (fra-til) | 154-160 |
Antal sider | 7 |
ISSN | 0005-2736 |
DOI | |
Status | Udgivet - 1993 |
Eksternt udgivet | Ja |
ID: 236891026