The effect of positive and negative pH-gradients on the stability of small unilamellar vesicles of negatively charged phospholipids.
The effect of positive and negative pH-gradients on the stability of small unilamellar vesicles of negatively charged phospholipids.
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正负 pH 梯度对带负电荷磷脂的单层小囊泡稳定性的影响。
DOI：
10.1016/0005-2736(93)90008-n
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
H. Hauser
中科院分区：
文献类型：
--
作者：
B. Lin;C. Yin;H. Hauser
本文研究了由带负电荷的磷脂酸盐经超声或pH跳跃法制备的单层小泡（SUV）的稳定性。作为囊泡稳定性的标准，使用：（I）根据荧光探针羧基荧光素（CF）的渗透性判断的双层完整性和（II）通过凝胶过滤和冷冻断裂电子显微镜判断的磷脂囊泡对融合的敏感性。根据这些标准，严格地说，其内腔与分散介质平衡的卵磷脂SUV（PA-SUV）是化学不稳定的。然而，从实际的角度来看，它们可以被视为稳定的。观察到CF释放的半衰期为14天，并且还观察到一些囊泡融合，特别是在低温（4°C）下。观察到的小影响，例如，囊泡发生融合的小趋势可能是由于PA双层的高表面电荷密度。这项工作的一个主要发现是，在pH跳跃方法中用于驱动从大磷脂酸双层片形成SUV的相同正pH梯度对所得PA-SUV具有稳定作用。通过约两个pH单位或更多的正pH梯度实现稳定，其中外部介质的pH超过囊泡腔的pH。在这些条件下，在4°C和室温下，长达约8周没有观察到包埋的CF的显著损失，也没有观察到SUV的融合。相反，施加到PA-SUV的几个pH单位的反向或负pH梯度（外部pH低于囊泡腔的pH）使PA-SUV不稳定。这样的梯度可以显示为导致脂质双层包装的显著扰动，如从CF渗透性的显著增加中明显的。磷脂双层的局部扰动伴随着大量囊泡融合，这在低温（4°C）下是突出的。
The stability of small unilamellar vesicles (SUV) made from negatively-charged phosphatidate by ultrasonication or pH-jump has been investigated. As criteria for the vesicle stability are used: (I) the bilayer integrity as judged from the permeability of the fluorescent probe carboxyfluorescein (CF) and (II) the susceptibility of the phospholipid vesicles to fusion as judged by gel filtration and freeze-fracture electron microscopy. Egg phosphatidate SUV (PA-SUV) whose internal cavity is in equilibrium with the dispersion medium are strictly speaking thermodynamically unstable by these criteria. They may, however, be regarded as stable from a practical point of view. CF-release is observed with a half-time of 14 days and also some vesicle fusion, particularly at low temperature (4°C). The small effects observed, e.g., the small tendency of the vesicles to undergo fusion is probably due to the high surface charge density of PA bilayers. A main finding of this work is that the same positive pH-gradient which is used in the pH-jump method to drive the formation of SUV from large phosphatidic acid bilayer sheets has a stabilizing effect on the resulting PA-SUV. Stabilization is achieved by positive pH-gradients of about two pH-units or more with the pH of the external medium exceeding the pH of the vesicle cavity. Under these conditions, up to about 8 weeks no significant loss of entrapped CF and no fusion of SUV was observed both at 4°C and room temperature. In contrast, a reverse or negative pH-gradient of several pH units applied to PA-SUV (with the external pH being lower than that of the vesicle cavity) destabilizes PA-SUV. Such a gradient can be shown to lead to a dramatic perturbation of the lipid bilayer packing as evident from a significant increase in CF permeability. The local perturbation of the phospholipid bilayer is accompanied by massive vesicle fusion which is prominent at low temperature (4°C).
自旋标记电子顺磁共振和差示扫描量热法研究线粒体细胞色素 C 氧化酶和三磷酸腺苷合酶复合物之间的相互作用。
影响因子：
2.9
作者：
Qiu,ZH;Yu,L;Yu,CA
通讯作者：
Yu,CA
用法国压力池制成的单层脂质体：一种简单的制备和半定量技术。
影响因子：
6.5
作者：
HamiltonJr,RL;Goerke,J;Guo,LS;Williams,MC;Havel,RJ
通讯作者：
Havel,RJ