title: Incorporation kinetics of lysolecithin into lecithin vesicles. Kinetics of lysolecithin-induced vesicle fusion.
abstract: The incorporation kinetics of L-palmitoylphosphatidylcholine (lysolecithin) into dimyristoyl- and dipalmitoylphosphatidylcholine vesicles and the subsequent aggregation and fusion of the vesicles into larger aggregates were studied by using stopped-flow rapid-mixing techniques. The half-times for the lysolecithin incorporation vary between 50 and 500 ms. The incorporation rate has a maximum in the temperature range of the vesicle phase transition. This process is not diffusion controlled. The rate-limiting step is the incorporation of the lysolecithin monomer into the liquid bilayer. After this fast process, a slow reaction in the 10-50-min time range is observed. The large irreversible increase in turbidity indicates aggregation and fusion of the vesicles. The initial step is a second-order reaction with respect to the vesicle concentration, indicating aggregation or fusion of two vesicles. The aggregation rate passes through a maximum at the phase transition temperature.
mesh_terms: D004134:Dimyristoylphosphatidylcholine; D007700:Kinetics; D008081:Liposomes; D008244:Lysophosphatidylcholines; D008433:Mathematics; D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D013696:Temperature
chemical_list: D008081:Liposomes; D008244:Lysophosphatidylcholines; D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D004134:Dimyristoylphosphatidylcholine