Meaning of activation energy in phospholipid multibilayers phase transitions.

K Lonhus, L Budianska, L Lisetski

Chemistry and physics of lipids 2017 Aug

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The question of the activation energy of phase transitions in lyotropic liquid crystal phases of model phospholipid membranes was considered. In our experiments, we obtained DSC thermograms of hydrated DPPC and DMPC at different scanning rates, and activation energy values were determined by a modification of Kissinger non-isothermal kinetics method. Using this approach the equivalent order of reaction corresponding to the phase transition can be determined alongside the activation energy. The cooperativity of both main transition and pre-transition was shown to be strongly dependent on scanning rate, asymptotically tending to a certain value at high rates, which corresponds to the number of lipid molecules in two concentric layers of hexagonal tiling. Changes in pretransition activation energy are shown to be proportional to changes in the system volume during the pretransition process, while the tail-length dependent part of the main transition activation energy is proportional to the jump in the number of gauche isomers. Copyright © 2017. Published by Elsevier B.V.

Citation

K Lonhus, L Budianska, L Lisetski. Meaning of activation energy in phospholipid multibilayers phase transitions. Chemistry and physics of lipids. 2017 Aug;206:53-59