Abstract
The ordered-fluid phase transition in lipid membranes is described within the framework of the Landau theory, a general theory for phase transitions. The long-range order of lipids is characterized by the orientational order of the hydrocarbon chains implying the ordered-fluid transition to be of first order. Approaching the transition from either side, thermodynamic fluctuations and response functions are shown to increase, e.g. the specific heat, the lateral compressibility, the permeability, and the lateral diffusion coefficient. A protein molecule incorporated in the membrane is represented as a boundary condition on the lipid order at the protein surface. In the surrounding lipid the perturbation falls off exponentially with the coherence length. Assuming the protein molecules to be distributed homogeneously in the membrane plane and the boundary condition to be temperature independent, the protein-induced shift of the transition temperature and the latent heat is calculated. The latent heat decreases linearly with the protein concentration until it vanishes at a critical point. The critical protein concentration is determined by the ratios of the coherence length to lipid and protein radii in the membrane plane. At the critical point the lipid specific heat, lateral compressibility, permeability, and lateral diffusion coefficient become maximal.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Dill K. A., Flory P. J. Interphases of chain molecules: Monolayers and lipid bilayer membranes. Proc Natl Acad Sci U S A. 1980 Jun;77(6):3115–3119. doi: 10.1073/pnas.77.6.3115. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Marcelja S. Lipid-mediated protein interaction in membranes. Biochim Biophys Acta. 1976 Nov 11;455(1):1–7. doi: 10.1016/0005-2736(76)90149-8. [DOI] [PubMed] [Google Scholar]
- Nagle J. F., Scott H. L., Jr Lateral compressibility of lipid mono- and bilayers. Theory of membrane permeability. Biochim Biophys Acta. 1978 Nov 2;513(2):236–243. doi: 10.1016/0005-2736(78)90176-1. [DOI] [PubMed] [Google Scholar]
- Owicki J. C., McConnell H. M. Theory of protein-lipid and protein-protein interactions in bilayer membranes. Proc Natl Acad Sci U S A. 1979 Oct;76(10):4750–4754. doi: 10.1073/pnas.76.10.4750. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Owicki J. C., Springgate M. W., McConnell H. M. Theoretical study of protein--lipid interactions in bilayer membranes. Proc Natl Acad Sci U S A. 1978 Apr;75(4):1616–1619. doi: 10.1073/pnas.75.4.1616. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pink D. A., Chapman D. Protein-lipid interactions in bilayer membranes: a lattice model. Proc Natl Acad Sci U S A. 1979 Apr;76(4):1542–1546. doi: 10.1073/pnas.76.4.1542. [DOI] [PMC free article] [PubMed] [Google Scholar]