INHIBITION OF MEMBRANE-FUSION BY LYSOPHOSPHATIDYLCHOLINE

The ability of lysophosphatidylcholine to inhibit membrane fusion at s ubsolubilizing concentrations (between 1 and 9 mol % with respect to t he membrane lipids) was examined. Fusion between N-methyldioleoylphosp hatidylethanolamine (DOPE) large unilamellar vesicles (LUV) and fusion between Sendai virus and N-methyl-DOPE LUV were measured. A contents mixing fusion assay was used for LUV fusion (ANTS/DPX), and a lipid mi xing assay (octadecylrhodamine B) was used for the virus fusion experi ments. Lysophosphatidylcholine was effective at inhibiting both LUV fu sion and Sendai virus/LUV fusion. Lysophosphatidylcholine also inhibit ed leakage from N-methyl-DOPE LUV. P-31 nuclear magnetic resonance dat a were obtained of N-methyl-DOPE in the presence of lysophosphatidylch oline. Lysophosphatidylcholine stabilized the lamellar phase and reduc ed the incidence of nonlamellar structures at all temperatures. The de stabilization of nonlamellar structures with a negative radius of curv ature may be a mechanism for inhibition of fusion by lysophosphatidylc holine in these systems.