Revised stability constant, spectroscopic properties and binding mode of Zn(II) to FluoZin-3, the most common zinc probe in life sciences.

Revised stability constant, spectroscopic properties and binding mode of Zn(II) to FluoZin-3, the most common zinc probe in life sciences.
J Inorg Biochem. 2016 May 13;
Authors: Marszałek I, Krężel A, Goch W, Zhukov I, Paczkowska I, Bal W
Abstract
2-[2-[2-[2-[bis(carboxylatomethyl)amino]-5-methoxyphenoxy]ethoxy]-4-(2,7-difluoro-3-oxido-6-oxo-4a,9a-dihydroxanthen-9-yl)anilino]acetate (FluoZin-3) is used very broadly in life sciences as intra- and extracellular Zn(II) sensor selective for Zn(II) over Co(II), Ca(II) and Mg(II) ions at their physiological concentrations. It has been used for determination of relative and absolute levels of exchangeable Zn(II) in cells and extracellular fluids. Despite its popularity, the knowledge of its acid/base and Zn(II) coordination abilities and of its spectroscopic properties remained very limited. Also the published conditional dissociation constant ((C)Kd) values at pH7.4 are slightly discrepant, (15nM or 8.9nM). In this work we determined the (C)Kd for Zn(II) complexation by FluoZin-3 at pH7.4 with nitrilotriacetic acid (NTA) as competitor using two independent methods: fluorimetry and UV-Vis spectroscopy. For the first time, we investigated FluoZin-3 alone and complexed with Zn(II) in the wide range of pH, determining the total of eight pKa values from fluorescence spectra and from various regions of UV-Vis spectra. The validated values of (C)Kd (9.1±0.4nM; -log (C)Kd=8.04) and of the abso...

Source: Journal of Inorganic Biochemistry - May 12, 2016 Category: Biochemistry Authors: Marszałek I, Krężel A, Goch W, Zhukov I, Paczkowska I, Bal W Tags: J Inorg Biochem Source Type: research