The influence of poly(L-lysine) on phospholipid polymorphism. Evidence that electrostatic polypeptide-phospholipid interactions can modulate bilayer/non-bilayer transitions.

31P-NMR shows that poly(L-lysine) binding to cardiolipin, phosphatidylserine or phosphatidylglycerol does not affect the macroscopic structure or local order (in the phosphate region) of the phospholipids. In the case of cardiolipin poly(L-lysine) inhibits the ability of Ca2+ to induce the hexagonal HII phase. Alternatively, poly(L-lysine) induces the hexagonal HII phase for a fraction of the phospholipids in phosphatidylethanolamine-cardiolipin (2:1) dispersions.