Abstract

It has been suggested that phosphatidylinositol (PI), a precursor for a messengers, forms lipid rafts in the membrane which are regulated by protein kinases and/or by the biophysical properties of this phospholipid. To better understand this raft formation, a simplified system comprising hydrogenated derivatives of soy PI was investigated. Analytical analysis using GC-FID and ESI-MS confirms that commercial PIH still contained 15% unsaturation. The effect of this unsaturation played a role in the phase behaviour, where a richer polymorphism for PIH compared to that of natural PI was observed. PIH phase separated at high pressures and all temperatures, which was confirmed by Brewster Angle Microscopy (BAM) at the air-water interface and AFM on Langmuir-Blodgett films deposited on mica. We report, for the first time, the presence of a condensed phase monolayer which was supported by the crystallographic data (GIXD) obtained for PIH. It was observed that phase separation of the monolayer becomes more apparent at all surface pressures as temperature increased.