The interfacial region of dipalmitoylphosphatidylcholine bilayers is perturbed by fusogenic amphipaths.
The interfacial region of dipalmitoylphosphatidylcholine bilayers is perturbed by fusogenic amphipaths.
复制标题
二棕榈酰磷脂酰胆碱双层的界面区域受到融合两性分子的干扰。
DOI：
10.1016/s0006-3495(96)79522-x
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发表时间：
1996
影响因子：
3.4
通讯作者：
Prevratil,J
中科院分区：
文献类型：
--
作者：
Lentz,BR;Wu,JR;Zheng,L;Prevratil,J
采用几种结构方法探讨了三种融合性和四种非融合性两通路对大单层双棕榈酰磷脂酰胆碱（DPPC）囊泡的影响。对于这些结构测量中的四种，观察到两路通路有利于聚乙二醇（PEG）诱导融合的能力与每种方法报告的结构微扰之间存在相关性。首先，探测双分子层上层区域的1-[4-（三甲氨基）苯基]-6-苯己-1,3,5-三烯（TMA-DPH）的荧光各向异性在先前发现的导致含有融合性两性通道的膜融合的PEG浓度范围内下降。对于非促聚变两性通路，各向异性随PEG浓度单调增加。位于双分子层疏水核心的类似探针的性质与融合性没有相关性，也没有探测膜水表面的探针的性质。其次，C=O拉伸的频率随着熔凝膜而非熔凝膜的相变加热而急剧上升，然后急剧下降。第三，在膜有序/无序相变中，含有熔融性两路通路的膜的C-O-C酯拉伸频率显著增加，是非熔融性两路通路的两倍。磷酸盐、胆碱和酰基链运动的光谱特征与熔断性没有这种相关性。最后，量热测量显示，低水平的促聚变两路通路消除了DPPC膜中的“预转变”（L β ->P β），而其他两路通路发生了转移，但没有消除这种转变。综上所述，这些结果表明，促聚变两性通道干扰了双分子层的界面或“骨干”区域，而不是DPPC双分子层的疏水核心、头基团或水界面区域。
Several structural methods were used to probe the influence of three fusogenic and four nonfusogenic amphipaths on large, unilamellar dipalmitoylphosphatidylcholine (DPPC) vesicles. For four of these structural measurements there was a correlation observed between the ability of an amphipath to favor poly(ethylene glycol) (PEG)-induced fusion and the structural perturbation reported by each method. First, the fluorescence anisotropy of 1-[4-(trimethylamino)phenyl]-6-phenyhexa-1,3,5-triene (TMA-DPH), which probes the upper region of the bilayer, decreased in the range of PEG concentrations previously found to cause fusion of membranes containing fusogenic amphipaths. For nonfusogenic amphipaths, the anisotropy increased monotonically with PEG concentration. The properties of similar probes that locate in the hydrophobic core of the bilayer showed no correlation with fusogenicity, nor did the properties of probes purported to sense the aqueous surface of the membrane. Second, the frequency of the C=O stretch increased and then decreased dramatically as fusogenic but not nonfusogenic membranes were heated through their phase transition. Third, there was a dramatic increase in the frequency of the C-O-C ester stretch at the membrane order/disorder phase transition for membranes containing fusogenic amphipaths, twice the increase observed for nonfusogenic amphipaths. The spectral characteristics of phosphate, choline, and acyl chain motions showed no such correlation with fusogenicity. Finally, calorimetric measurements showed that low levels of fusogenic amphipaths eliminated the "pretransition" (L beta-->P beta) in DPPC membranes, whereas other amphipaths shifted but did not eliminate this transition. Taken together, these results indicate that fusogenic amphipaths perturb the interface or "backbone" region of the bilayer rather than the hydrophobic core, the headgroup, or the water interface regions of DPPC bilayers.