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pubmed:abstractText |
The addition of polyanionic polymers such as poly(aspartic acid) (PASP), DNA or dextran sulfate to liposomes composed of phosphatidylcholine (PC) and cholesterol (CHOL) and bearing the quaternary ammonium detergent [[[(1,1,3,3-tetramethylbutyl)cresoxy]ethoxy]ethyl]dimethy lbe nzylammonium hydroxide (DEBDA[OH]) resulted in liposome aggregation and fusion. Liposome-liposome fusion was studied by using fluorescently labeled liposomes and fluorescence-dequenching (DQ) methods. Addition of monoanions, such as aspartate or acetate, to liposomes bearing DEBDA[OH] caused neither their aggregation nor liposome-liposome fusion. Aggregation of liposomes bearing DEBDA[OH] by the binding pair avidin-biotin did not result in their fusion. Fusion in such aggregated liposomes was observed by the addition of chaotropic anions, such as nitrate or thiocyanate, or by PASP. A variety of other quaternary ammonium detergents behaved similarly to DEBDA[OH] in their ability to confer fusogenic properties upon PC/chol liposomes. The relevance of these findings to the mechanism of liposome-liposome fusion is discussed.
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