title: Phase behavior of two-component lipid membranes: theory and experiments.
abstract: The structure of the ripple phase of phospholipid membranes remains poorly understood in spite of a large number of theoretical studies, with many experimentally established structural features of this phase unaccounted for. In this article we present a phenomenological theory of phase transitions in single- and two-component achiral lipid membranes in terms of two coupled order parameters: a scalar order parameter describing lipid chain melting, and a vector order parameter describing the tilt of the hydrocarbon chains below the chain-melting transition. This model reproduces all the salient structural features of the ripple phase, providing a unified description of the phase diagram and microstructure. In addition, it predicts a variant of this phase that does not seem to have been experimentally observed. Using this model we have calculated generic phase diagrams of two-component membranes. We have also determined the phase diagram of a two-component lipid membrane from x-ray diffraction studies on aligned multilayers. This phase diagram is found to be in good agreement with that calculated from the model.
authors.affiliation: Raman Research Institute, C. V. Raman Avenue, Bangalore 560 080, India.
authors.forename: Md Arif
authors.initials: MA
authors.lastname: Kamal
authors.forename: Antara
authors.initials: A
authors.lastname: Pal
authors.forename: V A
authors.initials: VA
authors.lastname: Raghunathan
authors.forename: Madan
authors.initials: M
authors.lastname: Rao
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D008958:Models, Molecular; D010743:Phospholipids / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D008051:Lipid Bilayers; D010743:Phospholipids; D015060:1,2-Dipalmitoylphosphatidylcholine; D004134:Dimyristoylphosphatidylcholine