The effects of A23187 on the phospholipid phase transition of large unilamellar vesicles (LUVs) as detected by ultrasound spectroscopy.
The effects of A23187 on the phospholipid phase transition of large unilamellar vesicles (LUVs) as detected by ultrasound spectroscopy.
复制标题
超声光谱检测到 A23187 对大单层囊泡 (LUV) 磷脂相变的影响。
DOI：
10.1016/0005-2736(90)90395-5
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Dunn,F
中科院分区：
文献类型：
--
作者：
Ma,LD;Magin,RL;Dunn,F
采用磷脂相变敏感技术，研究了疏水性Ca 2+载体A2 3187对二棕榈酰磷脂酰胆碱（DPPC）和二棕榈酰磷脂酰甘油（DPPG）的大单层囊泡（LUV：4：1（w/w））膜磷脂动力学的影响.用双晶体声学干涉仪测定了在磷脂相变附近LUV的单位波长超声吸收αλ随温度和频率的变化。差示扫描量热法（DSC）和电子自旋共振（ESR）也被用来探测烃侧链的热力学和分子环境。随着A23187含量的增加，LUV悬浮液的相转变温度（Tm）保持在42.0° C附近，而相转变时的αλ振幅急剧增大。在Tm处，发生αλ max的弛豫频率随着A23187含量的增加而降低，表明负责超声吸收的事件的弛豫速率降低。ESR研究表明，在双层的C-12区域中包含2和5摩尔%的A23187的双层的流动性没有变化。因此，LUV膜中的A23187减缓了磷脂双层的烃侧链在相变时的结构松弛。
The effect of the hydrophobic Ca 2+ ionophore, A23187, on the phospholipid dynamics of large unilamellar vesicle (LUVs: 4: 1 (w/w) mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) membranes, as a function of A23187 content, was investigated using techniques sensitive to the phospholipid phase transition. The ultrasonic absorption per wavelength, αλ, was determined with a double crystal acoustic interferometer, as a function of tempertaure and frequency for LUVs in the vicinity of their phospholipid phase transition. Differential scanning calorimetry (DSC) and electron spin resonance (ESR) were also employed to probe the thermodynamics and molecular environment of the hydrocarbon side chains. With increasing A23187 content, the phase transition temperature (T m _of the LUV suspensions remained near 42.0° C, while the amplitude of αλ at the phase transition incresed dramatically. At T m the relaxation frequency, were αλ max occurs, decreased with A23187 content, suggesting that the relaxation rate of the event responsible for the absorption of ultrasound decreased. The ESR studies showed no change in the fluidity of the bilayer with the inclusion of 2 and 5 mol% A23187 in the C-12 region of the bilayer. Therefore, A23187 in LUV membranes slows the structural relaxation of the hydrocarbon side chains of the phospholipid bilayer at the phase transition.