本研究在利用核磁共振儀(2H NMR)去探討由DPPC和POPE兩種脂質組成;以及由DPPC，POPE和麥角固醇(ergosterol)或膽固醇(cholesterol)三種脂質組成的人造細胞膜的物理性質。 以氘取代DPPC及POPE sn-1 鏈上的氫，藉此量測DPPC與POPE的行為。我們發現當DPPC與POPE混合之後，DPPC的相變溫度(Tm)降低，而POPE的Tm上升。在1:1 DPPC/POPE中，DPPC與POPE有相同的Tm且兩者的M1對溫度的變化相似。因此我們認為DPPC與POPE間有很強的交互作用，且這些分子均勻分佈在細胞膜上。此外，當脂質分子處於so狀態時，分子間的交互作用強度依序為：DPPC-DPPC > DPPC-POPE > POPE-POPE。 比較含固醇的細胞膜及未含固醇的細胞膜的結果，我們發現，在1:1 DPPC/POPE細胞膜中加入固醇會產生lo態。固醇會降低so態細胞膜的有序程度，但會增加在ld態細胞膜的有序程度。麥角固醇的效應比膽固醇弱。此外，不論有無加入固醇，DPPC與POPE間都具有強交互作用。我們也發現在含膽固醇的細胞膜中，膽固醇與DPPC與POPE的交互作用較平均;然而，在含麥角固醇的細胞膜中，麥角固醇-DPPC的交互作用大於麥角固醇-POPE。 This study focuses on the physical properties of model membranes for binary mixture containing DPPC and POPE, and ternary mixtures containing DPPC, POPE, and ergosterol or cholesterol using 2H NMR. DPPC and POPE were deuterium labeled alternatively such that the behavior of both DPPC and POPE can be observed. We found that mixing DPPC and POPE lowers the melting temperature Tm of DPPC, but raises the Tm of POPE. In this binary mixture, DPPC and POPE have the same Tm and similar temperature-dependence in their order parameter M1, suggesting a strong interaction between DPPC and POPE, and well mixing of the two lipids. In addition, the magnitude of lipid-lipid interaction in the so (gel or ) phase is in the following order: DPPC-DPPC > DPPC-POPE > POPE-POPE. The results of ternary mixtures containing sterol are compared with those of binary mixture to investigate the effect of sterol. The addition of sterol to 1:1 DPPC/POPE membranes promotes the formation of lo (liquid ordered phase) phase. Sterol decreases the order of gel-phase membranes, while increases that of ld (liquid disordered) phase membranes. The effect of ergosterol is less strong than cholesterol. In addition, the interaction between DPPC and POPE is strong with or without sterol. Regarding the lipid-sterol interaction, cholesterol interacts equally with both DPPC and POPE in the ternary mixtrure. However, ergosterol interacts more strongly with DPPC than with POPE in the ternary.
