title: beta-Galactosidase-induced destabilization of liposome composed of phosphatidylethanolamine and ganglioside GM1.
abstract: A novel type of liposome bilayer destabilization catalyzed by the enzyme, beta-galactosidase, is described. Unsaturated phosphatidylethanolamine (PE), an HII-phase-forming lipid, does not form stable liposomes at physiological temperature and pH. However, stable unilamellar liposomes can be prepared by mixing PE with a minimum of 5 mol% ganglioside GM1, a micellar-phase-forming lipid. Treatment of these GM1/PE liposomes with beta-galactosidase induces a rapid leakage (3-6 min) of the entrapped fluorescent dye, calcein. The studies indicate that liposome destabilization is the result of catalytic degradation of GM1, rather than a stoichiometric binding of GM1 by beta-galactosidase. Kinetic data indicate that the destabilization takes place via liposome collision. This simple, rapid method of liposome destabilization by beta-galactosidase will be useful in designing a liposome-based signal amplification mechanism for assays involving enzymes.
mesh_terms: D004355:Drug Stability; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005677:G(M1) Ganglioside / Q000378:metabolism*; D005696:Galactosidases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008051:Lipid Bilayers / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D013696:Temperature; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008081:Liposomes; D010714:Phosphatidylethanolamines; D005677:G(M1) Ganglioside; C020888:1,2-dielaidoylphosphatidylethanolamine; D005696:Galactosidases; D001616:beta-Galactosidase; C007740:fluorexon