含固醇的脂質雙層膜的形態及相行為的研究

廖英凱(Ying-Kai Liao)

指導教授 ： 薛雅薇

國立中央大學/理學院/生物物理研究所/碩士(2012年)

摘要

生物膜上存在著橫向異質(lateral heterogeneities)的特性，這些特性是因膜上有不同物理與化學性質的區塊(domain)。這些被稱為脂質筏(lipid raft)的區塊，含有高含量的膽固醇和神經鞘脂與GPI 錨泊蛋白。近期關於人造細胞膜的研究表示，固醇的加入可使膜產生lo 相。在DOPC、DPPC 及cholesterol 所組成的巨型單層微胞(GUV)上，則可觀察到七種不同的相與共存相。本論文主要利用螢光顯微術，以NBD-DOPE 作為標示液態無序相態(ld 相)的螢光探劑，觀察由DOPC、DPPC、ergosterol 所組成GUV 的螢光影像，以探討人造膜表面形態學及相行為與溫度和GUV 成分的關係。並藉由分析螢光影像中暗區的形狀歸納出GUV 上的小塊暗區(dark micro 區)為lo2 相，而大塊暗區(dark macro 區)為lo1 相。lo1 相比lo2 相有序。結果顯示，ergosterol 的加入會促進lo 相的形成，並可觀測到lo1+ lo2 + ld 共存。

關鍵字

生物物理 ； 脂雙層膜 ； 人造細胞膜 ； 螢光顯微術 ； 單層巨型微胞

並列摘要

The biological membrane has a feature of lateral heterogeneities. The feature is proposed to be a coexistence of domains which termed lipid rafts with different physical and chemical properties. Lipid rafts are enriched in cholesterol, sphingolipid, and GPI-anchored proteins. Recent evidence suggests that several sterols such as cholesterol and ergosterol are important to form liquid ordered phase (lo phase) in the lipid bilayer. Also, there are seven kinds of phases and coexistence phases are observed by the giant unilamellar vesicles (GUV) composed of DOPC, DPPC, and cholesterol. We investigate the membrane morphology and phase behavior of GUVs composed of DOPC, DPPC, and ergosterol using fluorescence microscopy. The NBD-DOPE is used to be a fluorescent probe to label the liquid disordered phase (ld phase). The fluorescent images of GUVs were studied as a function of temperature and composition. By analyzing the shape of dark-phase domains in the fluorescent image, we generalize the dark micro and dark macro regions are both in the lo phase, however the lo phase in the dark macro region is slightly ordered than that in the dark micro region. Our data shows that addition of ergosterol promotes the formation of lo phase. Moreover, coexistence of ld + lo1 + lo2 phase is observed.

並列關鍵字

biophysics ； Giant Unilamellar Vesicles ； fluorescence microscopy ； lipid bilayer

參考文獻

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