Phase transition of lipids

Seddon, J. M. (1990). Structure of the inverted hexagonal (HII) phase, and non-lamellar phase transitions of lipids, Biochim. Biophys. Acta, 1031, 1-69. 

Koynova R, Tenchov B (2009) Phase transitions of lipids. In Begley TP (ed) Wiley encyclopedia of chemical biology. Wiley, Hoboken, NJ, pp 601-615... 

Although DSC and other physical techniques have made considerable contributions to the elucidation of the nature of lipid-protein interactions, several outstanding questions remain. For example, it remains to be dehnitively determined whether some integral, transmembrane proteins completely abolish the cooperative gel-to-liquid-crystalline phase transition of lipids with which they are in direct contact or whether only a partial abolition of this transition occurs, as is suggested by the studies of the interactions of the model transmembrane peptides with phospholipids bilayers (see above). The mechanism by which some integral, transmembrane proteins perturb the phase behavior of very large numbers of phospholipids also remains to be determined. Finally, the molecular basis of the complex and unusual behavior of proteins such as the concanavalin A receptor and the Acholeplasma laidlawii B ATPase is still obscure (see Reference 17). 

Mabrey S, Sturtevant JM. Investigation of the phase transitions of lipids and lipid mixtures by high sensitivity differential scanning calorimetry. Proc. Natl. Acad. Sci. U.S.A. 1976 73 3862-3866. 

Shin Y-K, Ewert U, Budil DE, Ereed JH. Microscopic versus macroscopic diffusion in model membranes by electron spin resonance spectral-spatial imaging. Biophys. J. 1991 59 950-957. Trauble H, Sackmann E. Studies of the crystaUine-hquid crystalline phase transition of lipid model membranes, m. Structure of a steroid-lecitin system below and above the hpid-phase transition. J. Am. Chem. Soc. 1972 94 4499-4510. 

Membrane fluidity is determined by following anisotropic rotation of fluorescent or spin probes. Liquid-crystalline (or fluid) to gel thermotropic phase transition of lipids (Figure 1) (cf. Section 3.1.1 l)in liposomes or intact biomembranes can be followed by Fourier transform infrared (FTIR) spectroscopy or differential scanning calorimetry (DSC). 

The phase transition of lipid bilayers which comprise phospholipid mixtures, or phospholipids with different lengths of acyl chains, are of great importance due to their similarities with biomembranes or with lipid drug carriers such as liposomes, it is important to study the phase transitions and to detennine the exact crystalline mesophases of the mixed system. Thermal analysis studies indicated that the mi.xed lipids provide higher melting temperatures compared to those of pure lipids. This phenomenon occurrs w hen the lengths of the acyl chains are substantially different. 

IX. Role of Water Molecules in Phase Transitions of Lipids References... 

IX. ROLE OF WATER MOLECULES IN PHASE TRANSITIONS OF LIPIDS... 

The temperatiu-e at which the gel-to-hquid crystalline phase transition of lipid and surfactant bilayers occrus is an important characteristic of these systems. Maybrey and Sturtevant observed an increase in the phase transition temperature when palmitic acid was added to DMPC, but both increases and decreases can be observed with different fatty acids. It has been shown in Section II.A that the lateral and transverse motions of lipids in vesicle bilayers become more rapid as the temperature is increased from below to above Tq. This section reviews dynamic processes that occur in bilayers at around Tq. 

The phases and phase transitions of lipid monolayers H. Mohwald... 

In the pioneering simulations, the head groups of lipids were constrained on the plane surface. No explicit water molecules were included. Artificial and simple conformations and distributions of chains were used for the initial coordinates. Those simple simulations were, however, realistic enough to produce phase transitions of lipids, and elucidated details countering the kink model which was then a widely accepted... 

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