title: Promotion and inhibition of vesicle fusion by polylysine.
abstract: Polylysine induced rapid aggregation of large unilamellar vesicles composed of phosphatidylcholine-cardiolipin (1:1 molar ratio) but not their fusion. Application of the terbium-dipicolinic acid fusion assay showed that addition of polylysine at nanomolar concentrations enabled a significant lowering of the Ca2+ threshold concentration for vesicle fusion from 9 to 1 mM. Analysis of the kinetics of fusion with a mass-action kinetic model showed that polylysine enhanced significantly the rate of aggregation but affected only slightly the rate of fusion per se. Maximal enhancement of overall fusion rates occurred at a charge ratio (polylysine/cardiolipin) of about 0.5. At larger polylysine concentrations, e.g., at charge ratios greater than 3, polylysine inhibited vesicle fusion.
mesh_terms: D002122:Calcium Chloride; D002308:Cardiolipins; D007700:Kinetics; D008081:Liposomes; D008954:Models, Biological; D010713:Phosphatidylcholines; D010848:Picolinic Acids; D011107:Polylysine; D013725:Terbium
chemical_list: D002308:Cardiolipins; D008081:Liposomes; D010713:Phosphatidylcholines; D010848:Picolinic Acids; D013725:Terbium; D011107:Polylysine; D002122:Calcium Chloride; C004860:dipicolinic acid