A kinetic study of the growth of fatty acid vesicles
A kinetic study of the growth of fatty acid vesicles
复制标题
DOI：
10.1529/biophysj.104.039875
复制
发表时间：
2004-08-01
影响因子：
3.4
通讯作者：
Szostak, JW
中科院分区：
文献类型：
--
作者：
Chen, IA;Szostak, JW
由脂肪酸组成的膜泡可以在实验室条件下生长和分裂，从而提供了一个与细胞生命出现相关的模型系统。当碱性胶束被添加到缓冲的小泡中时，脂肪酸小泡会自发生长。为了研究这一过程的机制，我们使用停流动力学分析了非交换FRET探针在生长过程中被掺入预制囊泡中的稀释情况。油酸囊泡的生长分为两个阶段(快速和缓慢)，这表明脂肪酸进入预成囊泡的两条途径。我们认为，快速相是由预先形成的小泡在化学计量上所限制的，其结果是在小泡周围形成一层脂肪酸的“壳”，然后这种脂肪酸快速转移到预先形成的小泡中。较慢的相可能是由于加入了被困在中间状态的脂肪酸。我们提供了独立的证据，证明胶束从高pH转移到低pH后，胶束迅速转变为聚集的中间形式。我们的结果表明，在避免胶束/小泡比大幅瞬时增加的条件下，添加的油酸最有效地结合到油酸/油酸盐小泡中。
Membrane vesicles composed of fatty acids can be made to grow and divide under laboratory conditions, and thus provide a model system relevant to the emergence of cellular life. Fatty acid vesicles grow spontaneously when alkaline micelles are added to buffered vesicles. To investigate the mechanism of this process, we used stopped-flow kinetics to analyze the dilution of non-exchanging FRET probes incorporated into preformed vesicles during growth. Oleate vesicle growth occurs in two phases ( fast and slow), indicating two pathways for the incorporation of fatty acid into preformed vesicles. We propose that the fast phase, which is stoichiometrically limited by the preformed vesicles, results from the formation of a "shell'' of fatty acid around a vesicle, followed by rapid transfer of this fatty acid into the preformed vesicle. The slower phase may result from incorporation of fatty acid which had been trapped in an intermediate state. We provide independent evidence for the rapid transformation of micelles into an aggregated intermediate form after transfer from high to low pH. Our results show that the most efficient incorporation of added oleate into oleic acid/oleate vesicles occurs under conditions that avoid a large transient increase in the micelle/vesicle ratio.