Deuterium NMR Study of the effect of 7- dehydrocholesterol on the POPE Membranes

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/83334

Title:	Deuterium NMR Study of the effect of 7- dehydrocholesterol on the POPE Membranes
Authors:	鄭光佑;Chang, Kuang-Yu
Contributors:	生物物理研究所
Keywords:	7DHC;POPE;7DHC;POPE
Date:	2020-07-07
Issue Date:	2020-09-02 15:28:16 (UTC+8)
Publisher:	國立中央大學
Abstract:	固醇在生物膜的組成與功能中扮演了重要的角色。在含有膽固醇的人造細胞膜研究中發現，將膽固醇加入脂質膜中後會形成sterol-rich以及sterol-poor的區塊。一般認為這些處於liquid-ordered態的sterol-rich區塊為細胞膜上的脂筏。在本論文中，我們研究7- dehydrocholesterol (7DHC)對於POPE-d31膜在物理性質方面的影響。本研究使用氘核磁共振 (2H NMR) 來測量由POPE-d31和7- dehydrocholesterol (7DHC) 所組成的人造細胞膜。將不同濃度的7DHC樣品在不同溫度下量測已取得核磁共振光譜。光譜的M1值呈現出7DHC使膠態POPE脂膜變得無序，並使液晶態的脂膜變得有序。透過NMR光譜取得之溫度對7DHC濃度的POPE-d31脂質膜相圖顯示出膠態-液晶態共存與液晶態-inverted hexagonal態兩種兩相共存的區域，其中液晶態同時被發現在兩種兩相共存區域內。隨著7DHC濃度增加，液晶態從無序轉變成有序。這證明了POPE脂膜在含有7DHC時存在liquid-ordered 態。然而，在此系統中兩種液態相並沒有被觀測到同時存在。另一方面，7DHC 促進liquid-ordered態在膠態POPE脂膜中的形成。最後，高濃度與低濃度的7DHC對液晶態相變至inverted hexagonal態的影響有明顯的差異。;Sterols play important roles in membrane organization and functions. Model membranes containing cholesterol reveal that the addition of cholesterol in lipid membranes promotes sterol-rich, liquid-ordered-phase domains. In this work, we investigate the effect of 7- dehydrocholesterol (7DHC) on the physical properties of 1-palmitoyl(d31)-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE-d31) membranes using deuterium nuclear magnetic resonance. 2H NMR spectra are taken as a function of temperature and 7DHC concentration. The spectral first moments show that 7DHC disorders the gel phase and order the liquid-crystalline phase of POPE membranes. The phase diagram, constructed from the NMR spectra exhibits gel-liquid crystalline and liquid crystalline-inverted hexagonal phase coexistence regions. One liquid crystalline phase is observed in between these two two-phase regions. The liquid crystalline phase evolves from the liquid-disordered phase to the liquid-ordered phase as the 7DHC concentration increases. This is the first demonstration that liquid-ordered phase exists in POPE membranes containing 7DHC. However, liquid-liquid phase coexistence is not observed in this system. On the other hand, 7DHC promotes the liquid-ordered phase in the gel-phase POPE membranes. Finally, the liquid crystalline-to-inverted iii hexagonal phase transition exhibits dramatically different 7DHC concentration dependence at low and high concentrations.
Appears in Collections:	[Graduate Institute of Biophysics] Electronic Thesis & Dissertation

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