Ternary complex formation and competition quench fluorescence of ZnAF family zinc sensors
Ternary complex formation and competition quench fluorescence of ZnAF family zinc sensors
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DOI：
10.1039/c3mt00007a
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发表时间：
2013-01-01
期刊：
影响因子：
3.4
通讯作者：
Bal, Wojciech
中科院分区：
文献类型：
--
作者：
Staszewska, Anna;Kurowska, Ewa;Bal, Wojciech
我们目前对细胞内Zn（II）离子的热力学和动力学的理解很大程度上是基于荧光传感器分子的应用，用于实时研究和可视化Zn（II）离子的浓度、分布和运输。相对于其他生物金属离子，这类试剂具有对锌的高选择性。然而，它们对低分子量Zn（II）配体（lmwl）生理水平的敏感性问题尚未得到解决。我们跟踪了8种这样的化合物对ZnAF-1和ZnAF的荧光效应的影响，ZnAF是ZnAF家族中含有N， N-二（2-吡啶基甲基）乙二胺螯合单元的荧光素锌传感器的两个代表。等摩尔Zn(II)-ZnAF-1和Zn(II)-ZnAF-2F溶液与乙酸、磷酸、柠檬酸、甘氨酸、谷氨酸、组氨酸、ATP和谷胱甘肽的荧光滴定显示出强烈的荧光猝灭。这些结果可以解释为[ZnAF-Zn(II)-LMWL]三元配合物的形成以及ZnAF和lmwl之间对Zn（II）的竞争的相互作用。紫外-可见光谱滴定显示ZnAF-1荧光素部分与ATP和His之间存在超分子相互作用，但这不会导致荧光猝灭。因此，获得的结果表明，ZnAF传感器，其他目前使用的含有N， N-二（2-吡啶基甲基）乙二胺单元的锌传感器，以及一般情况下，所有不饱和Zn（II）配位球的传感器可能共同报告细胞代谢物和Zn（II）离子，导致生物锌的浓度和通量的错误陈述。
Our current understanding of the intracellular thermodynamics and kinetics of Zn(II) ions is largely based on the application of fluorescent sensor molecules, used to study and visualize the concentration, distribution and transport of Zn(II) ions in real time. Such agents are designed for high selectivity for zinc in respect to other biological metal ions. However, the issue of their sensitivity to physiological levels of low molecular weight Zn(II) ligands (LMWLs) has not been addressed. We followed the effects of eight such compounds on the fluorescence of ZnAF-1 and ZnAF-2F, two representatives of the ZnAF family of fluorescein-based zinc sensors containing the N, N-bis(2-pyridylmethyl)ethylenediamine chelating unit. Fluorescence titrations of equimolar Zn(II)-ZnAF-1 and Zn(II)-ZnAF-2F solutions with acetate, phosphate, citrate, glycine, glutamic acid, histidine, ATP and GSH demonstrated strong fluorescence quenching. These results are interpreted in terms of an interplay of the formation of the [ZnAF-Zn(II)-LMWL] ternary complexes and the competition for Zn(II) between ZnAF and LMWLs. UV-vis spectroscopic titrations revealed the existence of supramolecular interactions between the fluorescein moiety of ZnAF-1 and ATP and His, which, however, did not contribute to fluorescence quenching. Therefore, the obtained results show that the ZnAF sensors, other currently used zinc sensors containing the N, N-bis(2-pyridylmethyl) ethylenediamine unit, and, in general, all sensors that do not saturate the Zn(II) coordination sphere may co-report cellular metabolites and Zn(II) ions, leading to misrepresentations of the concentrations and fluxes of biological zinc.