Phase Transition of Lipid Multilamellar Aqueous Suspension under High Pressure I. Investigation of Phase Diagram of Dipalmitoyl Phosphatidylcholine Bimembrane by High Pressure-DTA and -Dilatometry

Abstract

The pressure and temperature phase diagrams of DPPC bilayers have been obtained by DTA and dilatometry. Under atmospheric pressure DPPC shows three phase transitions at 42°C, 36°C and around 18°C, corresponding to the main-, pre- and sub-transitions respectively. Throughout our experiments we discovered very interesting phenomena in these transitions due to the effect of pressure and are as follows. First, the presence of a tricritical point on the pre-transition line has been found at about 2.5 kbar and 78°C, where the first order transition changes to a second order transition. Second, the sub-transition could be observed under high pressure without annealing procedure which required to stock DPPC at about 0°C for three or four days under atmospheric pressure. Third, a new fourth transition below the sub-transition temperature has been discovered.

Enthalpy and Volume Changes in Lipid Membranes. I. The Proportionality of Heat and Volume Changes in the Lipid Melting Transition and Its Implication for the Elastic Constants

“…The pressure dependence of the melting transition has been investigated before by various authors. 12,13,16,[18][19][20][21]36,37 It has been shown that the shift of the lipid melting transition is linear with the applied hydrostatic pressure in a pressure range up to at least 2 kbar. However, these authors were mainly interested in the shift of the transition point.…”

“…Table 2) is comparable to previous studies for the transition temperature. The value for the proportionality factor, γ, averaged over various literature values yields a mean value γ j ) 7.34‚10 -4 mL/J for DMPC MLV, 12,14,16,20,21 γ j ) 7.07‚10 -4 mL/J for DPPC MLV, 14,16,[19][20][21]39,40 and γ j ) 7.63‚10 -4 mL/J for distearoyl phosphatidylcholine MLV. 13,20 Similar numbers where found for dieladioyl phoshatidylcholine and palmitoyl oleoyl phosphatidylcholine.…”

Comprehensive characterization of temperature- and pressure-induced bilayer phase transitions for saturated phosphatidylcholines containing longer chain homologs

“…On the other hand, the L ␤ I phase is also induced by an application of pressure. It was found that bilayers of CnPCs, such as dimyristoyl-PC (DMPC: C14PC) and dipalmitoyl-PC (DPPC: C16PC), form the fully L ␤ I phase under high pressure [10][11][12][13][14][15][16][17][18]. In the L ␤ I phase, hydrocarbon chains of the CnPC molecules in one of the monolayers constituting a bilayer extend beyond the region of the bilayer midplane and alternately interpenetrate into the other opposing monolayer.…”

Chain elongation of diacylphosphatidylcholine induces fully bilayer interdigitation under atmospheric pressure

“…Lipid bilayer membranes of diacylphosphatidylcholines (diacylPCs), of which two identical saturated fatty-acid chains are bound to the glycerol backbone by ester linkage, have been thoroughly examined by several physico-chemical techniques [1][2][3][4][5][6][7][8][9]. Such bilayer membranes form various kinds of phases depending upon experimental conditions, and the characteristic gel-phase polymorphism is observed.…”