Protein-induced leakage and membrane destabilization of phosphatidylcholine and phosphatidylserine liposomes

By using spectroscopic and colloidal chemistry methods we studied the interactions of globular proteins with phospholipid membranes in relation to protein-promoted membrane fusion. We considered the effect of protein sorption on the destabilization of phosphatidylcholine and phosphatidylserine liposome membranes. Experimentally, we injected the proteins into fluorophore-quencher embedded liposome dispersions and recorded the leakage of fluorophore-quencher from the liposomes' inner compartment, which is due to the protein-induced destabilization of the phospholipid membranes. The release of fluorophore-quencher strongly depends on the protein concentration. The existence of monovalent and polyvalent cations also influences the protein-induced membrane destabilization by affecting the hydrophobic and electrostatic interactions. (C) 1997 Elsevier Science B.V.