Description of the thermotropic behavior of membrane bilayers in terms of raman spectral parameters - a 2-state model

Abstract

An analytical expression is developed for describing the thermotropic behavior of membrane bilayers as studied by Raman spectroscopy. The expression is derived from a two-state model of the main gel to liquid crystalline phase transition in lipid bilayers. Experimental data for a variety of diacylphosphatidylcholines and their derivatives have been fit by least squares to the two-state expression to within currently achievable measurement error. Numerical techniques have been developed for placing bounds on the parameters of the two-state model in situations of sparse data in the phase transition region. By fitting the model to the measured spectroscopic data, estimates of the extent of cooperativity in the phase transition can be obtained in a systematic manner.

Polymorphism of ceramide 6: a vibrational spectroscopic and X-ray powder diffraction investigation of the diastereomers of N-(α-hydroxyoctadecanoyl)-phytosphingosine

“…A shift of the band position of the symmetric stretching vibration band is often interpreted as an increase of the conformational disorder. Phase transitions can be recognised as abruptly changes in band positions or band intensities (Kirchoff and Levin, 1987).…”

Progress in the analysis of Stratum corneum ceramides

“…It has been proved that vibrational spectra of lipids are particularly sensitive to the conformational, packing, and dynamical changes involving hydrocarbon chains [100,101]. Thus, it is a well-established method to utilize conformationally sensitive modes for evaluating the state of the order of hydrocarbon chains in terms of population of trans and gauche conformers, the packing behavior, and phase transitions.…”

Vibrational spectroscopic studies of newly developed synthetic biopolymers

“…64 Using this method, it is also difficult to detect phase transitions of materials with very low enthalpy. 65 Furthermore, the DSC method does not provide information regarding the structural and conformational changes occurring in the sample while undergoing the phase transition. On the other hand, infrared absorption and Raman scattering are unable to provide detailed thermodynamic information related to phase transitions, which could be important to understand the nature of such transitions.…”