Dangreau H, Joniau M, De Cuyper M, Hanssens I
Biochemistry. 1982 Jul 20;21(15):3594-8. doi: 10.1021/bi00258a010.
The nonconjugated bichromophoric molecule 1,3-di(1-pyrenyl)propane shows, besides the pyrene monomer fluorescence, a structureless emission due to an intramolecular excited dimer (excimer). In the case of intramolecular excimer forming systems, the ratio of the emission intensities of excimer vs. monomer (IE/IM) is sensitive to changes in membrane structure as will be illustrated here. The present molecule is a useful probe to report on lipid-protein interactions, at least in our model system. We have introduced it into the hydrocarbon layer of dimyristoylphosphatidylcholine vesicles in order to study their interaction with alpha-lactalbumin (alpha-LA) as a function of pH and temperature. On the basis of steady-state fluorescence, kinetic, and energy transfer studies, we have found that, at pH 4, alpha-LA strongly interacts with the lipid bilayer. In steady-state fluorescence experiments, changes of the ratio IE/IM and shifts of the transition temperature have been observed, reflecting changes of membrane structure caused by interaction with alpha-LA. Kinetic studies of the rate of interaction of alpha-lactalbumin and measurements of energy transfer from excited tryptophan(s) to the fluorescent probe confirm the steady-state experiments. Our results agree with previously reported microcalorimetric, gel chromatographic, and fluorescence polarization studies.
非共轭双发色团分子1,3 - 二（1 - 芘基）丙烷除了芘单体荧光外，还由于分子内激发二聚体（激基缔合物）呈现出无结构发射。在分子内激基缔合物形成系统的情况下，激基缔合物与单体的发射强度比（IE/IM）对膜结构的变化敏感，如下文所示。至少在我们的模型系统中，该分子是一种用于报道脂质 - 蛋白质相互作用的有用探针。我们已将其引入二肉豆蔻酰磷脂酰胆碱囊泡的烃层中，以研究其与α - 乳白蛋白（α - LA）的相互作用随pH值和温度的变化情况。基于稳态荧光、动力学和能量转移研究，我们发现，在pH 4时，α - LA与脂质双层强烈相互作用。在稳态荧光实验中，观察到IE/IM比值的变化和转变温度的偏移，反映了与α - LA相互作用引起的膜结构变化。α - 乳白蛋白相互作用速率的动力学研究以及从激发色氨酸到荧光探针的能量转移测量结果证实了稳态实验。我们的结果与先前报道的微量量热法、凝胶色谱法和荧光偏振研究结果一致。
