AUTOPOIETIC SELF-REPRODUCTION OF FATTY-ACID VESICLES
AUTOPOIETIC SELF-REPRODUCTION OF FATTY-ACID VESICLES
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DOI：
10.1021/ja00105a004
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发表时间：
1994-12-28
影响因子：
15
通讯作者：
LUISI, PL
中科院分区：
文献类型：
--
作者：
WALDE, P;WICK, R;LUISI, PL
描述了由辛酸和油酸在水中形成的囊泡能够进行自我复制的条件，即由于在囊泡本身的球形边界内发生的反应而增加其群体数量。这是通过让一定量的纯水不溶性辛酸或油酸酐在碱性pH下水解来实现的：释放的酸/羧酸盐的浓度的初始增加非常缓慢（几天达到自发囊泡形成的条件），但之后，囊泡的存在带来了快速的第二阶段，导致在整个自催化过程中形成越来越多的囊泡。在一组独立的实验中记录了辛酸和油酸囊泡对相应酸酐水解的催化能力。在这些实验中，水解在囊泡存在下在约对应于囊泡中酸的pK的pH下进行。辛酸和油酸囊泡的自生成自我复制过程被研究为温度的函数：通过增加温度（高达70摄氏度），囊泡形成的指数时间进展往往变得陡峭，而长的初始缓慢阶段显着缩短。辛酸和油酸囊泡的特征在于通过电子显微镜和通过确定其内部体积。这些囊泡是否以及在多大程度上形成一个经典的化学平衡系统，即自由表面活性剂与聚集体平衡的问题也进行了研究。
Conditions are described under which vesicles formed by caprylic acid and oleic acid in water are able to undergo autopoietic self-reproduction-namely an increase of their population number due to a reaction which takes place within the spherical boundary of tile vesicles themselves. This is achieved by letting a certain amount of the neat water-insoluble caprylic or oleic anhydride hydrolyze at alkaline pH: the initial increase of the concentration of the released acid/carboxylate is extremely slow (several days to reach the conditions for spontaneous vesicle formation), but afterwards, the presence of vesicles brings about a rapid second phase leading to more and more vesicles being formed in an overall autocatalytic process. The catalytic power of the caprylic acid and oleic acid vesicles toward the hydrolysis of the corresponding anhydride is documented in a set of independent experiments. In these experiments, the hydrolysis was carried out in the presence of vesicles at a pH corresponding approximately to the pK of the acid in the vesicles. The process of autopoietic self-reproduction of caprylic acid and oleic acid vesicles is studied as a function of temperature: by increasing temperature (up to 70 degrees C), the exponential time progress of vesicle formation tends to become steeper while the long initial slow phase is significantly shortened. The caprylic acid and oleic acid vesicles are characterized by electron microscopy and by determining their internal volume. The question whether and to what extent these vesicles form a classic chemical equilibrium system-in which namely the free surfactant is in equilibrium with the aggregates-is also investigated.