Effect of sodium cholate on the phase transition temperature of dipalmitoyl phosphatidylcholine

On treatment with sodium cholate, the phase transition temperature (Tc) of multilamellar liposomes derived from dipalmitoyl phosphatidylcholine (DPPC) progressively decreased with increasing cholate: lipid-P molar ratio. A molar ratio of 4.5 caused a one degree depression in Tc. The unilamellar cholate vesicles of DPPC exhibited the same Tc as that of the multilamellar ones. The formation of unilamellar vesicles from the multilamellar ones by cholate treatment was investigated by electron microscopy.