Synthesis, transport activity, membrane localization, and dynamics of oligoester ion channels containing diphenylacetylene units
作者:Joanne M. Moszynski、Thomas M. Fyles
DOI:10.1039/c0ob00194e
日期:——
Four new linear oligoesters containing a diphenylacetylene unit were prepared by fragment coupling sequences and the ion channel forming ability of the compounds was investigated. Activity in vesicles was very strongly controlled by overall length; the longest compound was effectively inactive. Planar bilayer studies established that all compounds are able to form channels, but that regular step changes in conductance depend on the location of the diphenylacetylene unit within the oligoester and on the electrolyte. The intrinsic fluorescence of the diphenylacetylene unit was used to probe aggregation and membrane localization. Both monomer (320 nm) and excimer (380 nm) emissions are quenched by copper ions; quenching of the excimer emission from an aqueous aggregate is very efficient. Time-dependent changes in the intensities of monomer and excimer emission show slow transfer of diphenylacetylene units from an aqueous aggregate to a membrane-bound monomer with subsequent growth of emission from a membrane-bound excimer. The latter species is not quenched by aqueous copper ions. The implications of these species and processes for the mechanism of ion channel formation by simple oligoesters are discussed.
制备了四种新型线性寡聚酯,其中包含二苯乙炔单元,并研究了这些化合物的离子通道形成能力。囊泡中的活性受到整体长度的强烈影响;最长的化合物几乎是非活性的。平面双层研究表明,所有化合物都能够形成通道,但导电性发生规律性阶跃变化取决于二苯乙炔单元在寡聚酯中的位置以及电解质的影响。利用二苯乙炔单元的内在荧光来探测聚集和膜定位。单体(320nm)和激基(380nm)发射均被铜离子猝灭;来自水相聚集体的激基发射被猝灭的效果非常显著。单体和激基发射强度的时间依赖变化表明,二苯乙炔单元从水相聚合物缓慢转移到膜结合的单体中,随后膜结合的激基发射逐渐增强。后者物种不受水相铜离子的猝灭。这些物种和过程对简单寡聚酯形成离子通道机制的影响进行了讨论。