DNA-induced fusion of phosphatidylcholine vesicles

We show that unilamellar vesicles composed of zwitterionic lipids such as dipalmitoylphosph-atidylcholine can fuse in the presence of DNA. Ca2+ ions are required to induce fusion. Nonradiative energy transfer was used to monitor the fusion process. The dependence of the extent and kinetics of fusion on the mode of preparation, the size of the vesicles, calcium concentration and lipid concentration was investigated. Small unilamellar vesicles of size less than 50 nm fuse rapidly, whereas vesicles larger than 100 nm will not fuse.