Yu B Z, Jain M K
Department of Chemistry, University of Delaware, Newark 19716.
Biochim Biophys Acta. 1989 Mar 27;980(1):15-22. doi: 10.1016/0005-2736(89)90194-6.
Fluorescence emission properties of a cationic indodicarbocyanine dye, NK-529, bound to anionic and zwitterionic vesicles, are examined under a variety of conditions to monitor lateral distribution of anionic amphiphiles in bilayers as a function of their phase properties. The change in the fluorescence properties of NK-529 arises from the binding of the dye to the bilayer that is dominated by ionic interactions when possible, as well as from the self-quenching of the dye bound to bilayers when the surface density of the dye is high. The binding affinity of the dye to anionic interfaces is more than 100-fold higher compared to that in zwitterionic bilayers. The limiting phospholipid/dye ratio in anionic bilayers at low vesicle concentrations is about 3. Thus the density of the bound dye in anionic bilayers can be more than 40-fold higher than that in zwitterionic bilayers, and therefore under such conditions the bound dye is completely self-quenched in vesicles or micelles of anionic phospholipids. The change in the fluorescence emission intensity on incorporation of anionic amphiphiles in zwitterionic bilayers is used to monitor segregation of the anionic amphiphiles. The organizational features of bilayers that cause a change in the fluorescence properties of bound NK-529 show that the lateral distribution of anionic amphiphiles is appreciably influenced not only by the mole fraction of the amphiphile but also in the presence of other additives, and by the gel-fluid thermotropic transition. As shown in the following paper, the fluorescence changes related to self-quenching in anionic bilayers containing NK-529 can be used to understand the organizational changes that occur during the course of interfacial catalysis by phospholipase A2 on zwitterionic bilayers.
研究了阳离子吲哚二碳菁染料NK - 529与阴离子和两性离子囊泡结合后的荧光发射特性，在各种条件下监测双层膜中阴离子两亲物的横向分布与其相性质的关系。NK - 529荧光性质的变化源于染料与双层膜的结合，在可能的情况下，这种结合以离子相互作用为主导，同时也源于当染料表面密度较高时，与双层膜结合的染料的自猝灭。与两性离子双层膜相比，该染料与阴离子界面的结合亲和力高出100多倍。在低囊泡浓度下，阴离子双层膜中磷脂/染料的极限比例约为3。因此，阴离子双层膜中结合染料的密度可比两性离子双层膜中的密度高40多倍，因此在这种条件下，结合染料在阴离子磷脂的囊泡或胶束中完全自猝灭。两性离子双层膜中掺入阴离子两亲物时荧光发射强度的变化用于监测阴离子两亲物的分离。导致结合的NK - 529荧光性质发生变化的双层膜组织特征表明，阴离子两亲物的横向分布不仅受到两亲物摩尔分数的显著影响，还受到其他添加剂的存在以及凝胶-流体热致转变的影响。如下文所示，与含NK - 529的阴离子双层膜中的自猝灭相关的荧光变化可用于理解磷脂酶A2在两性离子双层膜上进行界面催化过程中发生的组织变化。
