Hydration and molecular motions in synthetic phytanyl-chained glycolipid vesicle membranes
Hydration and molecular motions in synthetic phytanyl-chained glycolipid vesicle membranes
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DOI：
10.1016/s0006-3495(01)75970-x
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发表时间：
2001-12-01
影响因子：
3.4
通讯作者：
Handa, T
中科院分区：
文献类型：
--
作者：
Baba, T;Minamikawa, H;Handa, T
在pH7.0和25 ℃下，合成支链糖脂、1，3-二-O-植烷酰基-2-O-（β-D-麦芽三糖基）甘油（Mal（3）（PhYt）（2））以及支链磷脂、二植烷酰基磷脂酰胆碱（DPhPC）的质子跨膜渗透速率比直链脂质（如蛋黄磷脂酰胆碱（EPC））的质子跨膜渗透速率低约4倍。为了检查Mal（3）（PhY）（2）膜中的水渗透程度和分子运动是否可以解释较低的渗透性，将纳秒时间分辨荧光光谱应用于支链脂质（Mal（3）（PhYt）（2）、DPhPC和来自极端嗜热嗜酸古菌嗜酸热浆菌的四醚脂质）以及直链脂质的各种膜（EPC，1-棕榈酰-2-油酰-磷脂酰胆碱（POPC）和二半乳糖基二酰基甘油（DGDG））。在膜-水界面处，糖脂、Mal（3）（PhYt）（2）和DGDG的水化程度低于磷脂、EPC、POPC和DPhPC的水化程度。DPhPC表现出最高的水化脂质检查。同时，荧光磷脂在支链脂膜中的旋转和横向扩散运动比直链脂膜中的运动受到更大的限制。结果表明，支链脂膜的质子渗透性较低，而不是较低的水化链段的运动受到限制。
Proton permeation rates across membranes of a synthetic branch-chained glycolipid, 1,3-di-O-phytanyl-2-O-(beta -D-maltotriosyl)glycerol (Mal(3)(PhYt)(2)) as well as a branch-chained phospholipid, diphytanoylphosphatidylcholine (DPhPC) were lower than those of straight-chained lipids such as egg yolk phosphatidylcholine (EPC) by a factor of similar to4 at pH 7.0 and 25 degreesC. To examine whether degrees of water penetration and molecular motions in Mal(3)(PhY)(2) membranes can account for the lower permeability, nanosecond time-resolved fluorescence spectroscopy was applied to various membranes of branch-chained lipids (Mal(3)(PhYt)(2), DPhPC, and a tetraether lipid from an extremely thermoacidophilic archaeon Thermoplasma acidophilum), as well as straight-chained lipids (EPC, 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), and digalactosyldiacylglycerol (DGDG)) using several fluorescent lipids. Degrees of hydration of glycolipids, Mal(3)(PhYt)(2), and DGDG were lower than those of phospholipids, EPC, POPC, and DPhPC at the membrane-water interfaces. DPhPC showed the highest hydration among the lipids examined. Meanwhile, rotational and lateral diffusive motions of the fluorescent phospholipid in branch-chained lipid membranes were more restricted than those in straight-chained ones. The results suggest that the restricted motion of chain segments rather than the lower hydration accounts for the lower proton permeability of branch-chained lipid membranes.