Lateral Heterogeneity of Cholesterol on Binary Lipid Mixtures of POPC/CHOL: a Molecular Dynamics Study

Phase diagrams on ternary and quaternary lipid mixtures showing the existence of liquid-disordered (ld), liquid-ordered (lo) and a mixed phase (ld+lo) are now well established. Although the ld+lo is generally accepted for binary mixtures of cholesterol and phospholipids with saturated acyl chains, the existence of a phase separation in mixtures of cholesterol with phospholipids that have one saturated and one unsaturated acyl chain is not universally accepted. There are reports of a phase diagram on the mixtures POPC/Chol and POPC/Erg and nystatin activity co-related to this purported phase diagram; with a maximal activity appearing in the mixed phase.