Lapinski Monique M, Blanchard G J
Department of Chemistry, Michigan State University, East Lansing, MI 48824-1322, USA.
Chem Phys Lipids. 2008 Jun;153(2):130-7. doi: 10.1016/j.chemphyslip.2008.03.005. Epub 2008 Mar 21.
We have examined the temperature-dependent reorientation dynamics of perylene imbedded in bilayers of 1,2-dimyristoyl-sn-phosphatidylcholine (DMPC), where the bilayers exist in the form of unilamellar vesicles. Previous work using 100-nm diameter DMPC vesicles has shown that the phase transition from the gel phase to the fluid phase can be detected using the reorientation dynamics of perylene. In this work we explore the vesicle size dependence of the perylene reorientation dynamics in DMPC vesicles. The size of the vesicles is determined by extrusion and the reorientation dynamics of perylene are measured as a function of vesicle size between 100-nm and 5-microm diameter. We find that, while the phase transition for DMPC is seen in smaller vesicles, perylene becomes insensitive to the phase transition for vesicles larger than ca. 800-nm diameter. We also find a discontinuous change in perylene reorientation dynamics with increasing vesicle size, and we consider this result in the context of the location of perylene within the bilayer.
我们研究了嵌入1,2-二肉豆蔻酰-sn-磷脂酰胆碱（DMPC）双层膜中的苝的温度依赖性重取向动力学，其中双层膜以单层囊泡的形式存在。之前使用直径100 nm的DMPC囊泡的研究表明，利用苝的重取向动力学可以检测到从凝胶相到流体相的相变。在这项工作中，我们探讨了DMPC囊泡中苝重取向动力学对囊泡大小的依赖性。通过挤压确定囊泡大小，并测量直径在100 nm至5 µm之间的囊泡中苝的重取向动力学随囊泡大小的变化。我们发现，虽然在较小的囊泡中可以看到DMPC的相变，但对于直径大于约800 nm的囊泡，苝对相变变得不敏感。我们还发现随着囊泡大小增加，苝的重取向动力学存在不连续变化，并且我们在双层膜中苝的位置背景下考虑了这一结果。
