PDF(Pubmed)
Abstract：
The widely used Laurdan probe has two conformers, resulting in different optical properties when embedded in a lipid bilayer membrane, as demonstrated by our previous simulations. Up to now, the two conformers\' optical responses have, however, not been investigated when the temperature and the phase of the membrane change. Since Laurdan is known to be both a molecular rotor and a solvatochromic probe, it is subject to a profound interaction with both neighboring lipids and water molecules. In the current study, molecular dynamics simulations and hybrid Quantum Mechanics/Molecular Mechanics calculations are performed for a DPPC membrane at eight temperatures between 270K and 320K, while the position, orientation, fluorescence lifetime and fluorescence anisotropy of the embedded probes are monitored. The importance of both conformers is proven through a stringent comparison with experiments, which corroborates the theoretical findings. It is seen that for Conf-I, the excited state lifetime is longer than the relaxation of the environment, while for Conf-II, the surroundings are not yet adapted when the probe returns to the ground state. Throughout the temperature range, the lifetime and anisotropy decay curves can be used to identify the different membrane phases. The current work might, therefore, be of importance for biomedical studies on diseases, which are associated with cell membrane transformations.
摘要：
广泛使用的Laurdan探针有两个构象，当嵌入脂质双层膜时，会产生不同的光学特性，正如我们之前的模拟所证明的。到目前为止,这两个整合物的光学响应，然而,当温度和膜的相位变化时，没有进行调查。由于已知Laurdan既是分子转子又是溶剂化变色探针，它受到与相邻脂质和水分子的深刻相互作用。在目前的研究中,在270K和320K之间的八个温度下，对DPPC膜进行了分子动力学模拟和混合量子力学/分子力学计算，而位置,定位,监测嵌入探针的荧光寿命和荧光各向异性。通过与实验的严格比较，证明了两种构象的重要性，这证实了理论上的发现。可以看出，对于Conf-I，激发态寿命长于环境的松弛，而对于Conf-II,当探头返回到基态时，周围环境尚未适应。在整个温度范围内，寿命和各向异性衰减曲线可用于识别不同的膜相。目前的工作可能，因此,对疾病的生物医学研究很重要，与细胞膜转化有关。
