"Entropic traps"in the kinetics of phase separation in multicomponent membranes stabilize nanodomains
"Entropic traps"in the kinetics of phase separation in multicomponent membranes stabilize nanodomains
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DOI：
10.1529/biophysj.105.068502
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发表时间：
2006-07-01
影响因子：
3.4
通讯作者：
Zimmerberg, J.
中科院分区：
文献类型：
--
作者：
Frolov, V. A. J.;Chizmadzhev, Y. A.;Zimmerberg, J.
我们定量地描述了多组分脂质双层膜中相分离结构域的产生和进化。早期阶段，称为成核阶段和独立生长阶段，非常快（特征时间分别为亚毫秒和毫秒），系统由平均半径的纳米畴组成；类似于5-50 nm。接下来，领域的移动性变得重要；畴合并和裂变成为物质交换的主要机制，线张力是决定任何时间点畴尺寸分布的主要因素。对于足够小的伽马，由畴合并引起的熵项的减少大于边界能的减少，并且只存在纳米畴。当伽玛值较大时，边界能量的下降主导了不利的合并熵，合并导致纳米畴迅速扩大到微米尺度半径。在中间线张力和有限时间内，纳米畴可以保持分散并与新的全局相共存。快速形成大木筏所需的线张力的理论临界值与由巨大单层囊泡的出芽区曲率所得到的实验值是一致的。
We quantitatively describe the creation and evolution of phase-separated domains in a multicomponent lipid bilayer membrane. The early stages, termed the nucleation stage and the independent growth stage, are extremely rapid ( characteristic times are submillisecond and millisecond, respectively) and the system consists of nanodomains of average radius; similar to 5-50 nm. Next, mobility of domains becomes consequential; domain merger and fission become the dominant mechanisms of matter exchange, and line tension gamma is the main determinant of the domain size distribution at any point in time. For sufficiently small gamma, the decrease in the entropy term that results from domain merger is larger than the decrease in boundary energy, and only nanodomains are present. For large gamma, the decrease in boundary energy dominates the unfavorable entropy of merger, and merger leads to rapid enlargement of nanodomains to radii of micrometer scale. At intermediate line tensions and within finite times, nanodomains can remain dispersed and coexist with a new global phase. The theoretical critical value of line tension needed to rapidly form large rafts is in accord with the experimental estimate from the curvatures of budding domains in giant unilamellar vesicles.