Solid-fluid equilibrium chain molecules

Lipid domains and rafts in biological membranes are stabilized by several different interactions, including membrane-cytoskeleton, lipid-protein, and lipid-lipid interactions, and the organization can be both equilibrium and non-equilibrium in nature [27]. Lipid-domain formation caused by cooperative phenomena in the lipid bilayers is particularly important for the activation of SPLA2 [32-35]. The cooperative phenomena in lipid bilayers are caused by the fundamental interactions between the lipid molecules and are a consequence of the many-particle character of the supramolecular aggregate. The cooperativity leads to phase transitions and phase equilibria. The key cooperative event in many liposomal membranes is the so-called main phase transition, which takes the bilayer from a solid (gel) phase with conformationally ordered acyl chains to a fluid phase with conformationally disordered chains. The main transition in lipid bilayers is often accompanied by strong lateral density and compositional fluctuations. These fluctuations are manifested as dynamic lipid domains characterized by certain time and length scales that are determined by the thermodynamic conditions and the actual lipid species in question. 

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