CHOLESTERYL PHOSPHATE AND CHOLESTERYL PYROPHOSPHATE INHIBIT FORMATION OF THE HEXAGONAL PHASE

The effects of cholesteryl phosphate and cholesteryl sulfate on the LaHII phase transition temperature of dielaidoylphosphatidylethanolamine were compared. Both compounds raise the LaHII transition temperature. This effect is decreased with decreasing pH. Cholesteryl sulfate is a somewhat better bilayer stabilizer and the effect is observed to lower pH values. Cholesteryl pyrophosphate was synthesized. This compound raises the La<2.sbnd;HII transition temperature at pH 7.4 to the same extent as does cholesteryl sulfate. It is concluded that charged sterol amphiphiles are good bilayer stabilizers but that this effect is not very sensitive to the nature of the polar group. © 1990.