Effect of a Dynorphin A analog, E2078, on phospholipid membrane properties.

The effect of the Dynorphin A analog, E2078, on the physicochemical properties of lipid membranes was investigated. E2078 induces the leakage of calcein, especially out of negatively-charged vesicles. The peptide binds to dipalmitoylphosphatidylglycerol sonicated vesicles according to the Lamgmuir isotherm, with a binding constant of 4.0x10(5) M(-1) and a binding-site number of 0.14 per lipid molecule. The leakage seems to occur at a critical binding-site number of approx. 0.025 per lipid molecule. In addition, E2078 increased the membrane fluidity of the acidic lipid bilayer. In conclusion, E2078 interacts with acidic lipids through electrostatic interactions, inducing leakage and increasing membrane fluidity.