SHAPE TRANSITIONS AND SHAPE STABILITY OF GIANT PHOSPHOLIPID-VESICLES IN PURE WATER INDUCED BY AREA-TO-VOLUME CHANGES
SHAPE TRANSITIONS AND SHAPE STABILITY OF GIANT PHOSPHOLIPID-VESICLES IN PURE WATER INDUCED BY AREA-TO-VOLUME CHANGES
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DOI：
10.1016/s0006-3495(91)82117-8
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发表时间：
1991-10-01
影响因子：
3.4
通讯作者：
SACKMANN, E
中科院分区：
文献类型：
--
作者：
KAS, J;SACKMANN, E
通过温度的变化，改变了二肉豆烯酰磷脂酰胆碱（= DMPC）和棕榈酰磷脂酰胆碱（= POPC）在无离子水中的体积比，诱导了囊泡的形状变化。根据预处理的不同，我们发现（在纯水中）DMPC在增加面积体积比时发生了几种类型的形状变化：(a)在面积体积比进一步增加时出芽转变导致囊泡链的形成，(b)盘状细胞-口状细胞转变，(c)重入哑铃-梨-哑铃转变，以及(d)球形囊泡的自发起泡和/或系绳形成。除了这些转变外，还发现了一种更奇特的哑铃-盘状细胞转变(e)，它是通过局部不稳定进行的。梨、盘状细胞和气孔细胞在较小的温度变化下是稳定的，除非多余的面积接近出芽囊泡的极限形状对应的值，即小于或等于0.1℃的温度变化导致自发向内或向外出芽。对于POPC，我们观察到只有出芽过渡到内部，导致囊泡链或相同大小的子囊泡分布突出到囊泡内部。本文还报道了溶质影响的初步实验。前三种类型的形状转变可以用双层耦合模型来解释，假设两层单层的热膨胀系数差异很小。这并不适用于观察到的接近极限形状的不稳定性。
Shape transformations of vesicles of dimyristoylphosphatidylcholine (= DMPC) and palmitoyloleylphosphatidylcholine (= POPC) in ion-free water were induced by changing the area-to-volume ratio via temperature variations. Depending on the pretreatment we find several types of shape changes for DMPC (in pure water) at increasing area-to-volume ratio: (a) budding transitions leading to the formation of a chain of vesicles at further increase of the area-to-volume ratio, (b) discocyte-stomatocyte transitions, (c) reentrant dumbbell-pear-dumbbell transitions, and (d) spontaneous blebbing and/or tether formation of spherical vesicles. Beside these transitions a more exotic dumbbell-discocyte transition (e) was found which proceeded via local instabilities. Pears, discocytes, and stomatocytes are stable with respect to small temperature variations unless the excess area is close to values corresponding to limiting shapes of budded vesicles where temperature variations of less-than-or-equal-to 0.1-degrees-C lead to spontaneous budding to the inside or the outside. For POPC we observed only budding transitions to the inside leading either to chains of vesicles or to distributions of equally sized daughter vesicles protruding to the inside of the vesicle. Preliminary experiments concerning the effect of solutes are also reported. The first three types of shape transitions can be explained in terms of the bilayer coupling model assuming small differences in thermal expansivities of the two monolayers. This does not hold for the observed instabilities close to the limiting shapes.