Rex S
Department of Biophysical Chemistry, Biocenter of the University of Basle, Switzerland.
Biophys Chem. 1996 Jan 16;58(1-2):75-85. doi: 10.1016/0301-4622(95)00087-9.
We investigated the interaction of the peptide melittin with differently sized vesicles consisting of various lipid compositions. This system was characterized by dynamic light scattering to estimate the size of vesicles. For SUV we obtained a radius of 12 nm, for LUV 53 nm. The pore forming process of melittin in vesicles was investigated by efflux of encapsulated fluorescent dyes at a self-quenching concentration. The influence of the following parameters on efflux and pore formation was estimated: lipid composition (POPC and DOPC), vesicle size (SUV and LUV) and size of the encapsulated dye (carboxyfluorescein and FITC-dextran). We found that under similar conditions vesicles of DOPC give always less leakage than vesicles of POPC independent of the fluorescent dye. For SUV and LUV we have obtained a different leakage behaviour at identical surface concentrations of melittin (if the same partition coefficient is assumed). From efflux measurements with different dyes we concluded that 6-20 molecules of melittin are necessary to form a pore. The possibility that not pore formation but fusion is the mechanism of melittin induced efflux was disproved by fusion experiments using a resonance energy transfer assay.
我们研究了蜂毒肽与由不同脂质组成的不同大小囊泡之间的相互作用。该系统通过动态光散射来表征，以估计囊泡的大小。对于小单层囊泡（SUV），我们测得半径为12纳米，对于大单层囊泡（LUV）为53纳米。通过在自猝灭浓度下包封的荧光染料外流来研究蜂毒肽在囊泡中的成孔过程。评估了以下参数对染料外流和成孔的影响：脂质组成（1-棕榈酰-2-油酰磷脂酰胆碱（POPC）和1,2-二油酰-sn-甘油-3-磷酸胆碱（DOPC））、囊泡大小（SUV和LUV）以及包封染料的大小（羧基荧光素和异硫氰酸荧光素标记的葡聚糖）。我们发现，在相似条件下，无论使用何种荧光染料，DOPC囊泡的渗漏总是比POPC囊泡少。对于SUV和LUV，在蜂毒肽表面浓度相同的情况下（假设分配系数相同），我们观察到不同的渗漏行为。通过使用不同染料的外流测量，我们得出结论，形成一个孔需要6 - 20个蜂毒肽分子。利用共振能量转移测定法进行的融合实验否定了蜂毒肽诱导外流的机制不是成孔而是融合的可能性。
