Detection of bilayer packing stress and its release in lamellar-cubic phase transition by time-resolved fluorescence anisotropy.
Detection of bilayer packing stress and its release in lamellar-cubic phase transition by time-resolved fluorescence anisotropy.
复制标题
通过时间分辨荧光各向异性检测双层堆积应力及其在层状-立方相变中的释放。
DOI：
10.1021/jp046181z
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
T. Handa
中科院分区：
文献类型：
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作者：
M. Nakano;T. Kamo;A. Sugita;T. Handa
非片层形成的脂类引入到平面双层膜中会产生堆积应力，这对质膜的生物学功能至关重要，并且是片层-非片层相变的驱动力。本文研究了蛋黄磷脂酰胆碱和单油（MO）二元体系的相行为，以及脂类在层状-双连续立方相变中局部取向顺序的变化。小角X射线散射结果表明，当MO的摩尔分数（X(MO)）在0.6 ~ 0.7之间时，发生了片层-双连续立方相变。这些相分散形成脂质体和立方体体，以监测纳入的荧光探针的各向异性，其中Pluronic F127用作立方相的分散稳定剂，已被证明不会改变探针的立方结构和位置。对这些色散的时间分辨荧光各向异性测量表明，探针在片层相中的阶数参数随着X（MO）的增加而增加，在向立方相过渡期间下降。这一观察结果表明，加入非片状形成脂质所产生的堆积应力通过相变释放。
An introduction of nonlamellar-forming lipids into planar bilayers generates packing stress, which is important for the biological functions of plasma membranes and is a driving force for the lamellar-nonlamellar phase transition. We have investigated the phase behavior of a binary system consisting of egg yolk phosphatidylcholine and monoolein (MO) and the changes in the local orientation order of lipids in a lamellar-bicontinuous cubic phase transition. Small-angle X-ray scattering has revealed that the lamellar-bicontinuous cubic phase transition occurs at an MO molar fraction (X(MO)) between 0.6 and 0.7. These phases were dispersed to form liposomes and cubosomes to monitor the anisotropy of the incorporated fluorescence probe, in which Pluronic F127, used as a dispersion stabilizer of the cubic phase, has been proven not to alter the cubic structure and the location of the probes. Time-resolved fluorescence anisotropy measurements on these dispersions have revealed that the order parameter of the probe in the lamellar phase increases with increasing X(MO), and that it decreases during the transition to the cubic phase. This observation suggests that packing stress generated by the addition of the nonlamellar-forming lipid is released by the phase transition.