Enzyme association with lipidic Langmuir-Blodgett films: interests and applications in nanobioscience

Tilt angle of lipid acyl chains in unilamellar vesicles determined by ellipsometric light scattering

Ellipsometric light scattering (ELS) at room temperature is applied to unilamellar vesicles (approximately 50 nm radius) of 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the gel phase and of 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) in the liquid-crystaline phase. A high sensitivity of this technique to the local anisotropy is found. From the resulting local birefringence, a lower limit of (29 +/-0.5) degrees for the average tilt angle of the lipid chains of DPPC with respect to the membrane normal is estimated. This tilt angle value is slightly lower than literature values for the tilt angle in oriented lipid multi-bilayers on solid substrates.

P-glycoprotein effect on the properties of its natural lipid environment probed by Raman spectroscopy and Langmuir-Blodgett technique

Behavior of P-glycoprotein (Pgp) natural lipid environment within the membrane of CEM cells expressing Pgp in the quantities varying from 0% to 32% of the total amount of all membrane proteins is described for the first time. Observed cooperative effect of Pgp-induced increase of membrane stability, decrease of the temperature of gel-to-crystal lipids transition and predominance of the lipid liquid crystalline phase at physiological temperatures should have an impact in development of multidrug resistance phenotype of tumor cells by favoring the Pgp intercellular transfer and Pgp ATPase activity.