Effect of Vibrio vulnificus hemolysin on liposome membranes

The action of Vibrio vulnificus hemolysin (VVH), a cholesterol-binding hemolysin, on cholesterol-liposome suspensions was studied. It was observed that an internal marker, K⁺, of liposomes was released by treating with VVH. Kinetics of the release from the liposomes was almost identical to that from erythrocytes treated with VVH. When uni-lamellar liposomes loaded with the same amounts of K⁺ and Na⁺ were incubated with VVH, K⁺ release was more rapid than Na⁺ release. K⁺ release from non-cholesterol liposomes by VVH actions was also observed, but the amount of VVH required was larger than that in cholesterol liposomes. Therefore, it is thought that the existence of cholesterol in membranes might be important for VVH action.