Shape modification of phospholipid vesicles induced by high pressure: influence of bilayer compressibility.
Giant vesicles composed of pure egg yolk phosphatidylcholine (EYPC) or containing cholesterol (28 mol%) have been studied during a high hydrostatic pressure treatment to 285 MPa by microscopic observation. During pressure loading the vesicles remain spherical. A shape transition consisting of budding only occurs on the cholesterol-free vesicles during pressure release. The decrease in the volume delimited by the pure EYPC bilayer between 0.1 and 285 MPa was found to be 16% of its initial volume, whereas the bulk compression of water in this pressure range is only 10%. So the compression at 285 MPa induced a water exit from the pure EYPC vesicle. The shape transition of the EYPC vesicle during pressure release is attributed to an increase in its area-to-volume ratio caused by the loss of its water content during compression. Because bulk compression of the cholesterol-containing vesicle is close to that of water, no water transfer would be induced across the bilayer and the vesicle remains spherical during the pressure release.
Beney
L
L
Laboratoire de Génie des Procédés Alimentaires et Biotechnologiques, Ecole Nationale Supérieure de Biologie Appliquée à la Nutrition et à l'Alimentation, Dijon, France.
Perrier-Cornet
J M
JM
Hayert
M
M
Gervais
P
P
D002784:Cholesterol / Q000737:chemistry*; D006874:Hydrostatic Pressure; D008051:Lipid Bilayers / Q000737:chemistry*; D008858:Microscopy, Phase-Contrast / Q000295:instrumentation / Q000379:methods; D008968:Molecular Conformation; D010713:Phosphatidylcholines / Q000737:chemistry*; D013499:Surface Properties
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D002784:Cholesterol