Statistical mechanical analysis of Raman spectroscopic order parameter changes in pressure-induced lipid bilayer phase transitions

Abstract

The statistical mechanical cluster theory of Fisher as applied by Kanehisa and Tsong to phospholipid bilayers is modified to describe the effects of hydrostatic pressure on the state of an aqueous dispersion of the phospholipid dipalmitoyl phosphatidylcholine. A high pressure Raman scattering cell has been built to obtain the Raman spectra of aqueous dispersions of phospholipids as a function of the applied hydrostatic pressure from 0 to 100 atmospheres. Predicted thermal and pressure-induced phase transitions are compared with an experimentally obtained Raman order parameter derived from the ratio of two bands in the C-H stretching region of the Raman spectrum of the sample. The parameters of the theory are adjusted to obtain a satisfactory fit of the Raman order parameter versus temperature. The theory is then found to give an excellent prediction of the observed pressure dependence of the Raman order parameter with no changes in the adjustable parameters. The implications of the success of the theoretical fit is discussed. Particularly of interest is the rather high value of the critical temperature, Tc, for lipid bilayers which is predicted by the model.

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.…”

Toward a Philosophy and Theory of Volumetric Nonthermal Processing

“…Due to difficulty in access, many of these are optical in character, and are better suited to transparent samples than to foods. Techniques such as circular dichroism (Harris and others ), optical rotation (Andersen and Gronlund ), fluorescence (Ralston and others ), X‐ray diffraction (Stamatoff and others ), Raman spectroscopy (Yager and Peticolas ), and dynamic light scattering (Ceuterick and others ). Chemical relaxation techniques such as pressure jump (Heremans and others ), nanosecond temperature jump (Liphard ), and flash photolysis (Hasinoff ) have been used at high pressure.…”