Formation of ternary complexes with MgATP: effects on the detection of Mg2+ in biological samples by bidentate fluorescent sensors.
Formation of ternary complexes with MgATP: effects on the detection of Mg2+ in biological samples by bidentate fluorescent sensors.
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DOI：
10.1021/ic5000606
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发表时间：
2014-03-17
影响因子：
4.6
通讯作者：
Buccella D
中科院分区：
文献类型：
--
作者：
Schwartz SC;Pinto-Pacheco B;Pitteloud JP;Buccella D
基于β-酮酸双齿配位基序的荧光指示剂与目前基于邻氨基苯酚-N，N，O-三乙酸（APTRA）的螯合剂相比显示出上级的金属选择性特征，用于生物镁的研究。然而，这些低密度螯合剂可以允许与Mg 2+和细胞环境中存在的常见配体形成三元复合物。在这项工作中，吸收，荧光，和NMR光谱研究的开启和比率荧光指示剂的基础上4-氧代-4H-喹嗪-3-羧酸与Mg 2+和ATP，最丰富的生物镁螯合剂的相互作用，从而揭示了三元复合物的形成条件下相关的荧光成像。形成的三元物种elaborate可比或更大的光学变化比那些归因于单独的二元复合物的形成。在pH 7和25 °C下，三元和二元物质的荧光指示剂的解离在低毫摩尔范围内具有表观平衡常数。这些结果表明，这些双齿传感器是无法区分游离Mg 2+和MgATP的基础上的比率或强度为基础的稳态荧光测量，从而提出了挑战，从富含核苷酸的生物样品中的镁的荧光成像的结果的解释。低齿度β-酮酸荧光螯合剂与MgATP之间形成的三元复合物导致的光学响应类似于或大于其二元对应物的形成所引起的光学响应，从而对富含核苷酸的生物样品中离子化镁的研究提出了挑战。通过荧光成像。
Fluorescent indicators based on β-keto-acid bidentate coordination motifs display superior metal selectivity profiles compared to current o-aminophenol-N,N,O-triacetic acid (APTRA) based chelators for the study of biological magnesium. These low denticity chelators, however, may allow for the formation of ternary complexes with Mg2+ and common ligands present in the cellular milieu. In this work, absorption, fluorescence, and NMR spectroscopy were employed to study the interaction of turn-on and ratiometric fluorescent indicators based on 4-oxo-4H-quinolizine-3-carboxylic acid with Mg2+ and ATP, the most abundant chelator of biological magnesium, thus revealing the formation of ternary complexes under conditions relevant to fluorescence imaging. The formation of ternary species elicits comparable or greater optical changes than those attributed to the formation of binary complexes alone. Dissociation of the fluorescent indicators from both ternary and binary species have apparent equilibrium constants in the low millimolar range at pH 7 and 25 °C. These results suggest that these bidentate sensors are incapable of distinguishing between free Mg2+ and MgATP based on ratio or intensity-based steady-state fluorescence measurements, thus posing challenges in the interpretation of results from fluorescence imaging of magnesium in nucleotide-rich biological samples. The formation of ternary complexes between low-denticity β-keto-acid fluorescent chelators and MgATP leads to optical responses similar to or greater than those elicited by the formation of their binary counterparts, thus posing challenges in the study of ionized magnesium in nucleotide-rich biological samples by fluorescence imaging.
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