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首页> 外文期刊>Biochemistry >Low permeability of liposomal membranes composed of bipolar tetraether lipids from thermoacidophilic archaebacterium Sulfolobus acidocaldarius
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Low permeability of liposomal membranes composed of bipolar tetraether lipids from thermoacidophilic archaebacterium Sulfolobus acidocaldarius

机译：嗜热嗜酸性古生菌Sulfolobus acidocaldarius的双极性四醚脂质组成的脂质体膜的低渗透性

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The physical origin of the extremely high thermal stability of tetraether liposomes composed of the polar lipid fraction E (PLFE) from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius has been investigated. The leakage rate of trapped 5,6-carboxyfluorescein (5(6)CF) and the proton permeability in PLFE liposomes have been measured using fluorescence probe techniques in the temperature range of 25-85 degrees C, The results are compared with those obtained from nonarchaebacterial liposomes. Egg yolk phosphatidylglycerol (eggPG) and PLFE liposomes exhibit similar large negative zeta-potentials (-31 to -34 mV) and low permeability coefficients for 5(6)CF, indicating that membrane surface charge is responsible for the low leakage rate of 5(6)CF in PLFE liposomes. This assertion is confirmed by the observation of an increased leakage rate of 5(6)CF with deceasing membrane surface negative charge via varying the content of egg yolk phosphatidylcholine (eggPC) in eggPC/eggPG binary mixtures, Gel-state dipalmitoylphosphatidylcholine bilayers and PLFE liposomes exhibit similar permeability coefficients for 5(6)CF, suggesting that lipid packing also plays an important role in the low leakage rate of 5(6)CF. PLFE liposomes, especially those similar to 60 nm in diameter, are remarkably thermally stable in regard to proton permeability, which increases by less than 2 x 10(-10) cm/s from 25 to 82 degrees C,, The proton permeability comparison of various liposomes reveals that the tight and rigid lipid packing is the major contributor of the extremely low proton permeation in PLFE liposomes; the inositol moiety and the branched methyl groups may also contribute, but to a much lesser extent. [References: 45]
机译：已经研究了由嗜热嗜酸性古生菌Sulfolobus acidocaldarius的极性脂质组分E（PLFE）组成的四醚脂质体具有极高热稳定性的物理原因。使用荧光探针技术在25-85摄氏度的温度范围内测量了被捕获的5,6-羧基荧光素（5（6）CF）的泄漏率和质子渗透性在PLFE脂质体中的结果与从非古细菌脂质体。蛋黄磷脂酰甘油（eggPG）和PLFE脂质体显示出相似的大负ζ电势（-31至-34 mV）和5（6）CF的低渗透系数，表明膜表面电荷导致5（6）的低泄漏率6）PLFE脂质体中的CF。通过观察改变蛋黄卵磷脂/卵磷脂二元混合物，凝胶态二棕榈酰磷脂酰胆碱双层和PLFE脂质体中蛋黄磷脂酰胆碱（eggPC）的含量，增加的5（6）CF泄漏率和减少的膜表面负电荷，证实了这一观点。表现出相似的5（6）CF渗透系数，表明脂质堆积在5（6）CF的低泄漏率中也起着重要作用。 PLFE脂质体，尤其是直径约60 nm的脂质体，在质子渗透率方面具有显着的热稳定性，从25摄氏度到82摄氏度，质子渗透率增加不到2 x 10（-10）cm / s。各种脂质体表明，紧密而刚性的脂质堆积是PLFE脂质体中极低质子渗透的主要原因。肌醇部分和支链甲基也可能起作用，但程度要小得多。 [参考：45]

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