Favilla R, Stecconi G, Cavatorta P, Sartor G, Mazzini A
Department of Physics, University of Parma, Italy.
Biophys Chem. 1993 May;46(3):217-26. doi: 10.1016/0301-4622(93)80015-b.
The interactions of the dye 4',6-diamidino-2-phenylindole (DAPI) with phospholipids ordered in single bilayer vesicles of dioleylphosphatidylserine (DOPS) or dimyristoylphosphatidylcholine (DMPC) or micelles of monomyristoylphosphatidylcholine (MPC) have been investigated. Somewhat unexpectedly, the binding of this dye to such ordered structures is not affected by the ionic strength of the external medium, which suggests an embedding of DAPI into the hydrocarbon phase. The fluorescence enhancement of DAPI bound can be accomodated within a model previously proposed for the behaviour of DAPI bound to proteins (Mazzini et al., Biophys. Chem. 42 (1992) 101). From both static and dynamic anisotropy measurements, bound DAPI results severely restricted in its rotational freedom but insensitive to the temperature dependent phase transition of the saturated DMPC vesicles. The considerable tightness and specificity of the interactions between DAPI and ordered phospholipids are also deduced from preliminary fluorescence quenching studies (reduced accessibility of iodide ions towards DAPI bound and quenching effects by the chaotrop Nonidet P-40).
研究了染料4',6-二脒基-2-苯基吲哚（DAPI）与在二油酰磷脂酰丝氨酸（DOPS）或二肉豆蔻酰磷脂酰胆碱（DMPC）的单双层囊泡中有序排列的磷脂，或与肉豆蔻酰磷脂酰胆碱（MPC）胶束之间的相互作用。有点出乎意料的是，这种染料与这些有序结构的结合不受外部介质离子强度的影响，这表明DAPI嵌入到了烃相中。结合的DAPI的荧光增强可以用先前提出的关于DAPI与蛋白质结合行为的模型来解释（Mazzini等人，《生物物理化学》42 (1992) 101）。从静态和动态各向异性测量结果来看，结合的DAPI的旋转自由度受到严重限制，但对饱和DMPC囊泡的温度依赖性相变不敏感。DAPI与有序磷脂之间相互作用的相当紧密性和特异性也可从初步的荧光猝灭研究中推断出来（碘离子对结合的DAPI的可及性降低以及离液剂Nonidet P-40的猝灭作用）。
