Interaction of Spermine with Dimyristoyl-l-α-phosphatidyl-dl-glycerol Multilamellar Liposomes

Polycationic spermine interacts with the negative phosphate group of dimyristoylphosphatidylglycerol multilamellar liposomes, forming a positively charged shell around the vesicle surface. An association costant of (2.15 ± 0.45) × 103m−1between spermine and the phospholipid groups in liposomes has been evaluated by a new and rapid enzymatic method. ESR spectra show that the effects of this polycation on liposomes are substantially different from those of cations like Ca2+and Mg2+and confirm the ability of spermine to induce liposome aggregation and not fusion.