STUDY OF VESICLE LEAKAGE INDUCED BY MELITTIN
STUDY OF VESICLE LEAKAGE INDUCED BY MELITTIN
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DOI：
10.1016/0005-2736(95)80035-e
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发表时间：
1995-05-04
影响因子：
3.4
通讯作者：
LAFLEUR, M
中科院分区：
文献类型：
--
作者：
BENACHIR, T;LAFLEUR, M
以钙黄绿素为荧光标记物，研究了膜扰动两亲性多肽蜂毒素对1-棕榈酰-2-油酰磷脂酰胆碱(POPC)大单层囊泡的渗漏作用。泄漏的程度已被发现由蜂毒素/脂的摩尔比来调节。蜂毒素能使捕获的钙黄素从一些囊泡中完全释放。这种要么全有要么全无的机制导致了两个不同的囊泡种群共存：‘空的’和完整的。未观察到蜂毒素的囊泡间迁移。结果揭示了蜂毒素对裂解小泡的特异性靶向。中性POPC基质中带负电荷的脂类(未质子化棕榈酸或1-棕榈酰基-2-油酰磷脂酰甘油)抑制蜂毒素的裂解能力；这种抑制作用随着表面电荷密度的增加而增强。有人提出，肽在带电表面的锚定防止了允许泄漏的缺陷的形成。基于囊泡上的多肽分子的随机分布，提出了一个统计模型来描述蜂毒素诱导的释放。有人提出，每个囊泡大约需要250个蜂毒素分子才能影响双层通透性，并将囊泡中的内容物排空。这个大的数字表明，渗漏更有可能是由于多肽对膜的集体扰动，而不是由于形成了一个明确的孔。
The leakage induced by melittin, a membrane-perturbing amphipathic peptide, from large unilamellar 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) vesicles was studied using calcein as fluorescent marker. The extent of leakage has been found to be regulated by the melittin/lipid molar ratio. Melittin leads to the complete release of trapped calcein from some vesicles. This all-or-none mechanism leads to the co-existence of two different vesicle populations: the 'empty' and the intact one. Intervesicular migration of melittin was not observed. The results reveal a specific targeting of the lysed vesicles by melittin. The presence of negatively charged lipids (unprotonated palmitic acid or 1-palmitoyl-2-oleoylphosphatidylglycerol) in the neutral POPC matrix inhibits the lytic power of melittin; this inhibition increases with increasing surface charge density. It is proposed that the anchorage of the peptide on the charged surface prevents the formation of defects allowing leakage. A statistical model based on a random distribution of the peptide molecules on the vesicles is proposed to describe the release induced by melittin. It is proposed that about 250 melittin molecules per vesicle are required to affect the bilayer permeability and to empty a vesicle of its content. This large number suggests that leakage is more likely due to collective membrane perturbation by the peptide rather than to the formation of a well-defined pore.