Phase behavior and glass transition of 1,2-dioleoylphosphatidylethanolamine (DOPE) dehydrated in the presence of sucrose

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• 作者：Shalaev ; Evgenyi Y. ; Steponkus ; Peter L.
• 关键词：Phosphatidylethanolamine ; Sucrose ; Dehydration ; Glass transition ; Phase transition ; Phospholipid ; PC ; phosphatidylcholine ; PE ; phosphatidylethanolamine ; DOPE ; 1 ; 2-dioleoyl-sn-glycero-3-phosphatidylethanolamine ; DPPC ; 1 ; 2-dipalmitoyl-sn-glycero-3-phosphati
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：2001
• 出版时间：September 3, 2001
• 年：2001
• 卷：1514
• 期：1
• 页码：100-116
• 全文大小：659 K

文摘

The effect of sucrose on the phase behavior of 1,2-dioleoylphosphatidylethanolamine (DOPE) as a function of hydration was studied using differential scanning calorimetry and X-ray diffraction. DOPE/sucrose/water dispersions were dehydrated at osmotic pressures (Π) ranging from 2 to 300 MPa at 30°C and 0°C. The hexagonal II-to-lamellar gel (H_II→L_β) thermotropic phase transition was observed during cooling in mixtures dehydrated at Π≤35 MPa. After dehydration at Π≥57 MPa, the H_II→L_β thermotropic phase transition was precluded when sucrose entered the rigid glassy state while the lipid was in the H_II phase. Sucrose also hindered the H_II-to-lamellar crystalline (L_c), and H_II-to-inverted ribbon (P_δ) lyotropic phase transitions, which occurred in pure DOPE. Although the L_c phase was observed in dehydrated 2:1 (mole ratio) DOPE/sucrose mixtures, it did not form in mixtures with higher sucrose contents (1:1 and 1:2 mixtures). The impact of sucrose on formation of the ordered phases (i.e., the L_c, L_β, and P_δ phases) of DOPE was explained as a trapping of DOPE in a metastable H_II phase due to increased viscosity of the sucrose matrix. In addition, a glass transition of DOPE in the H_II phase was observed, which we believe is the first report of a glass transition in phospholipids.