Fox Christopher B, Uibel Rory H, Harris Joel M
Department of Bioengineering, University of Utah, 50 South Central Campus Drive, Salt Lake City, Utah 84112-9202, USA.
J Phys Chem B. 2007 Oct 4;111(39):11428-36. doi: 10.1021/jp0735886. Epub 2007 Sep 12.
The study of phospholipid phase transitions is important for understanding drug- and protein-membrane interactions as well as other phenomena such as trans-membrane diffusion and vesicle fusion. A temperature-controlled stage on a confocal Raman microscope has allowed phase transitions in optically trapped phospholipid vesicles to be monitored. Raman spectra were acquired and analyzed using self-modeling curve resolution, a multivariate statistical analysis technique. This method revealed the subtle spectral changes indicative of sub- and pretransitions and main transitions in vesicles composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). The Raman scattering results were compared to differential scanning calorimetry (DSC) experiments and found to be in good agreement. This method of observing lipid phase transition profiles requires little sample preparation and a minimal amount of lipid (<or=0.1 nmol) for an experiment. The conformational changes of the phospholipid molecules occurring during phase transitions are elucidated from the Raman spectroscopy results. The evolution of chain decoupling, rotational disorder, and gauche defects in the lipid acyl chains as a function of temperature is described.
磷脂相变的研究对于理解药物与蛋白质和膜的相互作用以及其他现象（如跨膜扩散和囊泡融合）非常重要。共聚焦拉曼显微镜上的温度控制平台使得能够监测光学捕获的磷脂囊泡中的相变。使用自建模曲线分辨率（一种多元统计分析技术）采集并分析拉曼光谱。该方法揭示了由1,2 - 二棕榈酰 - sn - 甘油 - 3 - 磷酸胆碱（DPPC）组成的囊泡中指示亚转变、预转变和主要转变的细微光谱变化。将拉曼散射结果与差示扫描量热法（DSC）实验进行比较，发现两者吻合良好。这种观察脂质相变图谱的方法所需的样品制备很少，且每次实验所需的脂质量极少（≤0.1 nmol）。从拉曼光谱结果中阐明了相变过程中磷脂分子的构象变化。描述了脂质酰基链中链解耦、旋转无序和gauche缺陷随温度的变化情况。
