Membranes lipid temperature dependent phase

I assume there must be some temperature dependence of hapten binding. Is there any correlation (or absence of correlation) with solid-liquid lipid phase transitions (i.e., with membrane fluidity) ... 

Membrane lipids are invariably polymorphic that is, they can exist in a variety of kinds of organized structures, especially when hydrated. The particular polymorphic form that predominates depends not only on the stmcture of the lipid molecule itself and on its degree of hydration, but also on such variables as temperature, pressure, ionic strength and pH (see References 11 and 12 and article Lipids, Phase Transitions of). However, under physiologically relevant conditions, most (but not all) membrane lipids exist in the lamellar or bilayer phase, usually in the lamellar liquid-crystalline phase but sometimes in the lamellar gel phase. It is not surprising, therefore, that the lamellar gel-to-liquid-crystalline or chain-melting phase transition has been the most intensively studied lipid phase transition... 

Mention should be made here of the recently developed technique of pressure perturbation calorimetry (PPC), which measures the temperature-dependent volume change of a solute or colloidal particle in aqueous solution. PPC can also be used to detect thermotropic phase transitions in lipid model membranes and to characterize the accompanying volume changes and the kinetics of the phase transition. PPC essentially measures the heat change that results from small pressure changes at a constant temperature in a high-sensitivity isothermal calorimeter. For an excellent recent review on PPC as applied to lipid systems, the reader is referred to Heerklotz (19). 

An illustration of a lipid-water phase diagram, in which the transitions are driven by water content, is shown in Fig. 2 (43). A similar phase sequence can be produced by changes in temperature as well, and phospholipid phase diagrams generally exhibit pronounced temperature dependence. A generalized phase sequence of thermotropic phase transitions for the typical membrane lipids can be defined (44) ... 

Certainly, more complex lipid systems, such as the three-component "raft"-mixtures may represent more realistic models for biomembrane systems. Their pressure dependent lateral organization and phase behavior has not been studied yet, however. Some data are available on pressure effects on lipid extracts from natural membranes, such as bipolar tetraether liposomes composed of the polar lipid fraction E (PLFE) isolated from the thermoacidophilic archaeon Sulfolobus acidocaldarius. The SAXS data on PLFE multilamellar vesicles also exhibit several temperature dependent lamellar phases, and, in addition, the existence of cubic... 

Figure 12. Temperature-dependence of the fraction of liquid crystalline lipid (() and the heterogeneity parameter ("Aj, proportional to the mean square deviation of the order parameter) for the H NMR spectra of Acholeplasma laidlawii membranes shown in Figure 11 (C-14 0-m-d3 90%). The calorimetric phase transition temperature is indicated by Tc. (Unpublished data of H. C. Jarrell, R. Deslauriers, and...

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