低pH值稳定二棕榈油酰磷脂酰乙醇胺膜中的反相六角II相。
Low pH Stabilizes the Inverted Hexagonal II Phase in Dipalmitoleoylphosphatidylethanolamine Membrane.
作者信息
Li Shu Jie, Yamazaki Masahito
机构信息
Department of Physics, Dalian University, Dalian Economic and Technical Development Zone, Dalian, 116622 China ; Division of Protein Crystallography, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita-shi Osaka, 565-0871 Japan.
出版信息
J Biol Phys. 2004 Jan;30(4):377-86. doi: 10.1007/s10867-004-7894-3.
Dipalmitoleoylphosphatidylethanolamine (DPOPE) membrane is in the L(α) phase in neutral pH at 20 °C. The results of small-angle X-ray scattering (SAXS) indicate that an L(α) to H(II) phase transition in DPOPE membranes occurred at pH 1.9 in the absence of salt, and at pH 2.8 in the presence of 0.5 M KCl, at fully hydrated condition at 20 °C. The spontaneous curvature of DPOPE monolayer membrane did not change with a decrease in pH values. To elucidate the mechanism, we have investigated the effect of the cationic dioctadecyldimethylammonium (DODMA) on the structure and phase behavior of DPOPE membrane. The result shows that DODMA stabilizes the H(II) phase rather than the L(α) phase in DPOPE membrane at its low concentrations. Based on these results, the H(II) phase stability of DPOPE membrane due to low pH is discussed in terms of the spontaneous curvature of the monolayer membrane and the packing energy of acyl chains in the membrane.
二棕榈油酰磷脂酰乙醇胺（DPOPE）膜在20℃中性pH条件下处于L(α)相。小角X射线散射（SAXS）结果表明，在20℃完全水合条件下，无盐时DPOPE膜在pH 1.9时发生从L(α)相到H(II)相的转变，在存在0.5 M KCl时在pH 2.8时发生转变。DPOPE单层膜的自发曲率不会随pH值降低而改变。为阐明其机制，我们研究了阳离子型二辛基二甲基铵（DODMA）对DPOPE膜结构和相行为的影响。结果表明，在低浓度下，DODMA能稳定DPOPE膜中的H(II)相而非L(α)相。基于这些结果，从单层膜的自发曲率和膜中酰基链的堆积能方面讨论了低pH导致的DPOPE膜H(II)相稳定性。
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