Increase in size of sonicated phospholipid vesicles in the presence of detergents

Abstract

Triton X-100, sodium dodecylsulphate, sodium cholate, and beta-octylglucoside increase the size of sonicated, but not of unsonicated, phospholipid vesicles above the Tc gel to liquid-crystalline transition temperature. Lysophosphatidylcholine or glyceryl monooleate do not increase liposome size under these circumstances. The observed phenomenon of vesicle growth is virtually unaffected by phospholipid composition, surface potential, calcium ions, EDTA, or albumin. The presence of cholesterol makes the vesicles more susceptible to detergent-induced growth. The presence of detergents, even at concentrations much lower than required to observe any increase in vesicle size, favors the liberation of vesicle contents. These results may have implications concerning membrane fusion as well as the reconstitution of membrane proteins in the presence of detergents.

Cholesterol reverts Triton X‐100 preferential solubilization of sphingomyelin over phosphatidylcholine: A 31P‐NMR study

“…it opposes residing in positively-curved micelles much more strongly than either PC or SM. From this perspective, Chol should reduce the solubilization, as indeed observed in early papers [41,42]. Although Chol hinders specifically SM solubilization, R sat e values (Fig.…”

Effect of detergents and fusogenic lipids on phospholipid phase transitions

“…The "foreign" molecules under consideration are all surface active agents, that can be divided into two groups: the first one consists solely of lysolecithin, a lipid showing fusogenic properties on cell membrane systems, but not on liposomes (Howell & Lucy, 1969;Alonso et al, 1982a) and the second one consists of the surfactants Triton X-100, SDS, sodium cholate and octylglucoside, that can induce "fusion" (or increase in size) of sonicated DPPC vesicles above T c (Alonso et al, 1982a). As this study concerns the detergents as potential fusogenic agents, the lipid-detergent mixtures have been prepared so that the detergent was externally added to the already-made liposome preparation, just as the fusogenic lipid is added to the cell suspension.…”

“…Lysolecithin was from Sigma. The characteristics of the detergents have been described elsewhere (Alonso et al, 1982a).…”

“…Previous studies from this laboratory have shown (Alonso et al, 1981(Alonso et al, , 1982a) that some detergents, such as Triton X-100, SDS, sodium cholate or octylglucoside, induce an increase in size of sonicated liposome suspensions, that could be associated to liposome fusion. Other amphipathic molecules, e.g.…”

Compartmentalization of ceramide signaling: physical foundations and biological effects

“…Under similar conditions, C2-dihydroceramide did not induce any leakage (Simons and Gear, 1998). The significance of these observations is obscured by the fact that sonicated (as opposed to extruded) unilamellar vesicles are inherently metastable, and most soluble amphiphiles can lyse them (Alonso et al, 1982). Also, as mentioned above, aqueous dispersions/solutions of short-chain "soluble" ceramides have not yet been adequately characterized.…”