FLUORESCENCE LIFETIME DISTRIBUTIONS OF 1,6-DIPHENYL-1,3,5-HEXATRIENE IN PHOSPHOLIPID-VESICLES
FLUORESCENCE LIFETIME DISTRIBUTIONS OF 1,6-DIPHENYL-1,3,5-HEXATRIENE IN PHOSPHOLIPID-VESICLES
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DOI：
10.1021/bi00387a019
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发表时间：
1987-06-30
期刊：
影响因子：
2.9
通讯作者：
GRATTON, E
中科院分区：
文献类型：
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作者：
FIORINI, R;VALENTINO, M;GRATTON, E
采用多频相荧光法测定了1,6-二苯基-1,3,5-六三烯（DPH）在1,2-二棕榈酰-3-sn-磷脂酰胆碱和1,2-二myristoyl-3-sn-磷脂酰胆碱多层囊泡中的荧光发射特性。通过假设衰减由指数分量的离散和组成或衰减由寿命分量的一个或多个连续分布组成，分析了磷脂囊泡中DPH的荧光衰减。用指数来拟合衰减曲线至少需要两项，而简化后的。2相对较大。使用寿命值连续分布的拟合使用两个连续分量。使用了几种对称分布函数：均匀分布、高斯分布和洛伦兹分布。最能描述衰减的分布函数是洛伦兹函数。当温度低于相变温度时，洛伦兹分布的半峰全宽约为0.6 ns。在磷脂相转变和较高温度下，分布变得很窄，宽度约为0.1 ns。提出了DPH分子的寿命分布是由不同介电常数表征的不同环境连续体产生的。在凝胶相的转变温度以下，沿膜法向的介电常数梯度决定了衰减率的分布。在相变以上，在液晶相中，DPH分子的平移和旋转迁移率增加，并且DPH在激发态寿命期间经历平均环境。因此，分布变得更窄。寿命值的连续分布的物理解释是基于DPH分子的分子环境的异质性，这比使用离散数字或指数成分更好地描述了观察到的衰减。
The fluorescence emission properties of 1,6-diphenyl-1,3,5-hexatriene (DPH) in 1,2-dipalmitoyl-3-sn-phosphatidylcholine and 1,2-dimyristoyl-3-sn-phosphatidylcholine multilamellar vesicles have been measured by using multifrequency phase fluorometry. The fluorescence decay of DPH in the phospholipid vesicles has been analyzed by assuming either that the decay is made up of a discrete sum of exponential components or that the decay is made up of one or more continuous distributions of lifetime components. The fit of the decay curve using exponentials required at least two terms, and the reduced .chi.2 was relatively large. The fit using a continuous distribution of lifetime values used two continuous components. Several symmetric distribution functions were used: uniform, Gaussian, and Lorentzian. The distribution function that best described the decay was the Lorentzian. The full width at half-maximum of the Lorentzian distribution was about 0.6 ns at temperatures below the phase transition temperature. At the phospholipid phase transition and at higher temperatures, the distribution became quite narrow, with a width of about 0.1 ns. It is proposed that the lifetime distribution is generated by a continuum of different environments of the DPH molecule characterized by different dielectric constants. Below the transition temperature in the gel phase, the dielectric constant gradient along the membrane normal determines the distribution of decay rates. Above the transition, in the liquid-crystalline phase, the translational and rotational mobility of the DPH molecule increases, and the DPH experiences an average environment during the excited-state lifetime. Consequently, the distribution becomes narrower. The physical interpretation of the continuous distribution of lifetime values is based on the heterogeneity of the molecular environments of the DPH molecule, and this better describes the observed decay than the use of a discrete number or exponential components.