Krishnaswamy Rema, Rathee Vikram, Sood A K
Department of Physics, Indian Institute of Science, Bangalore 560012, India.
Langmuir. 2008 Oct 21;24(20):11770-7. doi: 10.1021/la8019765. Epub 2008 Sep 27.
The aggregation properties of an antibiotic membrane-active peptide alamethicin at the air-water interface have been studied using interfacial rheology and fluorescence microscopy techniques. Fluorescence microscopy of alamethicin monolayers revealed a coexistence of liquid expanded (LE) and solid phases at the surface concentrations studied. Interfacial oscillatory shear measurements on alamethicin monolayers indicate that its viscoelastic properties are determined by the area fraction of the solid domains. The role of zwitterionic phospholipids dioleoylphosphatidyl choline (DOPC) and dioleoylphosphatidyl ethanolamine (DOPE) on the peptide aggregation behavior was also investigated. Fluorescence microscopy of alamethicin/phospholipid monolayers revealed an intermediate phase (I) in addition to the solid and LE phase. In mixed monolayers of phospholipid (L)/alamethicin (P), with increase in L/P, the monolayer transforms from a viscoelastic to a viscous fluid with the increase in area fraction of the intermediate phase. Further, a homogeneous mixing of alamethicin/lipid molecules is observed at L/P > 4. Our studies also confirm that the viscoelasticity of alamethicin/phospholipid monolayers is closely related to the alamethicin/phospholipid interactions at the air-water interface.
利用界面流变学和荧光显微镜技术研究了抗生素膜活性肽阿拉米辛在气-水界面的聚集特性。阿拉米辛单分子层的荧光显微镜显示，在所研究的表面浓度下，存在液体扩张（LE）相和固相的共存。对阿拉米辛单分子层进行的界面振荡剪切测量表明，其粘弹性特性由固体区域的面积分数决定。还研究了两性离子磷脂二油酰磷脂酰胆碱（DOPC）和二油酰磷脂酰乙醇胺（DOPE）对肽聚集行为的作用。阿拉米辛/磷脂单分子层的荧光显微镜显示，除了固相和LE相外，还存在中间相（I）。在磷脂（L）/阿拉米辛（P）的混合单分子层中，随着L/P的增加，单分子层随着中间相面积分数的增加从粘弹性流体转变为粘性流体。此外，在L/P>4时观察到阿拉米辛/脂质分子的均匀混合。我们的研究还证实，阿拉米辛/磷脂单分子层的粘弹性与气-水界面处的阿拉米辛/磷脂相互作用密切相关。
