Department of Chemistry, Korea University, Seoul 136-701, Republic of Korea.
Biomaterials. 2012 Jan;33(3):945-53. doi: 10.1016/j.biomaterials.2011.10.040. Epub 2011 Nov 1.
A series of coumarin fluorophores (1-3), each bearing a double bond conjugated quinoline unit that can undergo a Michael-type reaction with thiol-containing compounds, is reported. These systems, designed to provide so-called turn-on changes in fluorescence response when exposed to thiols, act as fluorescent chemical sensors for cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). In the case of 1, selectivity for Cys over Hcy and GSH is observed, both in terms of analyte-induced signal enhancement and response time. On the basis of fluorescence spectroscopic analyses, DFT calculations, and pH dependent studies this substrate selectivity is ascribed to steric interactions between the substituents on the quinolone units present in 1 and the targeted thiols, as well as to the comparatively lower pK(a) value of Cys relative to Hcy and GSH. In aqueous solution, probe 1 was found capable of detecting Cys with a detection limit of 10(-7) m. This system was successfully applied to the fluorescence imaging of intracellular Cys in HepG2 cells.
报道了一系列香豆素荧光团（1-3），每个荧光团都带有一个双键共轭的喹啉单元，可与含巯基的化合物发生迈克尔加成反应。这些系统旨在提供所谓的在暴露于巯基时荧光响应的“开启”变化，可用作半胱氨酸（Cys）、同型半胱氨酸（Hcy）和谷胱甘肽（GSH）的荧光化学传感器。对于 1，在分析物诱导的信号增强和响应时间方面，都观察到对 Cys 相对于 Hcy 和 GSH 的选择性。基于荧光光谱分析、DFT 计算和 pH 依赖性研究，这种底物选择性归因于存在于 1 中的喹啉单元上的取代基与目标巯基之间的空间相互作用，以及 Cys 相对于 Hcy 和 GSH 相对较低的 pK(a) 值。在水溶液中，发现探针 1 能够以 10(-7) M 的检测限检测 Cys。该系统成功应用于 HepG2 细胞内 Cys 的荧光成像。
