| Summary: | 碩士 === 國立中央大學 === 物理研究所 === 97 === Liquid domains in model membranes are frequently studied as models of lipid raft domain in plasma membrane. Studies show that membrane is in lo+ld phase coexistence that lo phase is believed to enrich in sterol and high melting-temperature (Tm) lipid while ld phase is formed by low Tm lipid. In this work, we study the phase behaviors and properties of binary and ternary mixture containing Dipalmitoyl- phosphatidylcholine (DPPC) as high Tm lipid, Palmitoyloleoylphosphatidylcholine (POPC) as low Tm lipid, and ergosterol or cholesterol as sterol using 2H-NMR. For the experiment, POPC and DPPC are deuterium-labeled in turn, such that information regarding each lipid component can be obtained. NMR spectra were taken as a function of temperature.
The result shows that the chain order of DPPC is greater than that of POPC in all mixtures studied. In 1:1 DPPC/POPC binary mixture, so+ld phase coexistence is observed in a wide temperature range. The presence of sterol promotes the formation of lo phase in ternary mixtures. Lipid-cholesterol interactions are stronger than lipid-ergosterol interactions within 1:1:1 DPPC/POPC/sterol. Furthermore, the influence of ergosterol on the lipid-lipid interactions is not as robust as that of cholesterol. Cholesterol enhances the DPPC-POPC interaction significantly and super exchange coupling between DPPC and POPC via cholesterol is important.
|
|---|
