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標題: | 甲基肌醇半乳?喃糖對乾燥人工脂囊膜之保護與脂質相變溫度之抑制 Protection of Dehydrated Liposome and Depression of Phase Transition Temperature by Galactopinitol |
作者: | Yung-Wen Kuan 關詠文 |
出版年 : | 2003 |
學位: | 碩士 |
摘要: | 本研究目的是探討銀合歡種子內發現的雙糖-甲基肌醇半乳?喃糖(galactopinitol)對人工脂囊膜(artificial lipid vesicles)的保護作用,並探討galactopinitol與蔗糖(sucrose)、海藻糖(trehalose)、棉子糖(raffinose)、水蘇糖(stachyose)等醣類組合抑制脂質相變溫度(phase transition temperature;Tm)的效果。各種醣類對人工脂囊膜的保護率由高到低依序是sucrose>galactopinitol>trehalose>raffinose>stachyose>glucose。而兩種及三種醣類混合的處理上,只要是加了galactopinitol的醣類組合,保護效果都比不加galactopinitol的其他醣類組合要好。結合已發表的人工脂囊膜耐旱測試紀錄,推論galactopinitol一如sucrose在保護乾燥膜系上所扮演的角色。以傅立葉轉換紅外線光譜儀(Fourier transform infrared spectroscopy; FTIR)測試時,發現sucrose和galactopinitol抑制oleoyl-palmitoyl phosphatidylcholine(OPPC)Tm值的效果與之前樣品的處理過程有關。以galactopinitol處理時,第一次掃描的Tm值約41℃,第二次掃描時Tm值大幅降到-40℃。結果顯示galactopinitol與OPPC分子產生交互作用。另外,OPPC分別以不加醣類與加galactopinitol之後乾燥處理,發現phosphate asymmetric stretch由1250cm-1下降到1235cm-1,顯示galactopinitol與磷形成氫鍵,這一點和Tm值大幅下降的分析結果一致(Crowe et al. 1996)。galactopinitol與OPPC交互作用在穩定乾燥膜系扮演了重要的角色。以含有galactopinitol的醣類組合處理OPPC,可以使OPPC的Tm值比其他醣類組合更低。各種醣類組合對抑制OPPC Tm值的效果不同。sucrose/raffinose處理得的Tm值為-25.5℃,galactopinitol/sucrose或galactopinitol/raffinose處理可使OPPC Tm值再下降6到12℃。在中、低相對溼度(RH12%、RH43%)下,OPPC以galactopinitol處理比sucrose處理所得Tm值低。以上結果支持galactopinitol與脂質分子有更強的交互作用,所以能有效抑制Tm值,並對人工脂囊膜有較好的保護效果。顯示galactopinitol可能有特殊的化學結構和物化性質,致使其具有較佳的抑制Tm值效果。 This study examined the efficiency for protecting artificial membrane of galactopinitol, a novel galactocyclitol from Leucaena leucoephala seeds, and used various combinations of galactopinitol, sucrose, trehalose, raffinose and stachyose to determine their effectiveness in depressing phase transition temperature (Tm) in dry oleoyl-palmitoyl phosphatidylcholine (OPPC). The order of effectiveness in protecting lipid vesicles is sucrose > galactopinitol > trehalose > raffinose > stachyose > glucose. On the other hand, the efficiency for protecting lipid vesicles of the mixtures of galactopinitol with other sugars is better than the mixtures without galactopinitol. Accompanied with published vesicle leakage experiments, this study suggests the role of galactopinitol plays in protection of dehydrated liposome is like that of sucrose. The Fourier transform infrared spectroscopy (FTIR) experiment shows that the effectiveness of sucrose and galactopinitol in depressing Tm in dry OPPC depends on the thermal history of the sample. When OPPC dried with galactopinitol is heated for the first time, Tm is about 41 ℃, but on the second heating scan Tm falls to about - 40℃. Results obtained with Tm indicate that galactopinitol interact with OPPC. In addition, when OPPC are dried with galactopinitol, the vibrational frequency of the phosphate of the polar headgroup of OPPC is depressed relatively to the controls. We have interpreted this effect due to hydrogen bonding between galactopinitol and the phosphate of the polar headgroup. This inference agreed with the observation that galactopinitol depresses Tm of OPPC. This interaction between galactopinitol and OPPC may be an important factor to stabilize dry membranes. The mixture of sugars showed different ability to depress Tm of OPPC. Sucrose / raffinose mixture allowed the Tm to -25.5℃, and galactopinitol / sucrose or galactopinitol / raffinose mixture provided an additional 6 to 12℃ depression. Under the 12% or 43% relative humidity, galactopinitol also gave a lower Tm value than sucrose. These result supported that there is a stronger interaction between galactopinitol and OPPC, so that galactopinitol depressed Tm efficiently, and there werw better protection for lipid vesicles. The low Tm value of OPPC treated with galactopinitol indicated the differences of physical and chemical properties from other sugars. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/75404 |
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顯示於系所單位: | 植物科學研究所 |
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