A capillary electrophoretic (CE) method using a short-sweep approach and laser-induced fluorescence (LIF) detection (ShortSweepCE-LIF) was developed for determination of Zn2+ and Cd2+ as complexes with highly selective and sensitive fluorescent probe FluoZin-3. The ShortSweepCE-LIF method, established in this work, can be used for examining competitive Zn2+ and Cd2+ binding properties of metalloproteins or peptides. The parameters including background electrolyte composition, injection pressure and time as well as separation voltage were investigated. Under the optimized conditions, 80 mM HEPES, pH 7.4, with 1.5 μM FluoZin-3 was used as an electrolyte, hydrodynamic injection was performed at 50 mbar for 5 s, and separation voltage of 25 kV. Limits of detection for Zn2+ and Cd2+ were 4 and 125 nM, respectively. The developed method was demonstrated in a study of interactions between metalothionein-2a isoform and metal ions Zn2+, Co2+ and Cd2+. It was found that FluoZin-3 was able to extract a single Zn2+ ion, while added Co2+ (in surplus) extracted only 2.4 Zn2+ ions, and Cd2+ extracted all 7 Zn2+ ions present in the metalothionein molecule.

Department of Chemical Biology Faculty of Biotechnology University of Wroclaw Joliot Curie 14a 50 383 Wrocław Poland

Department of Chemistry and Biochemistry Mendel University in Brno Zemedelska 1 CZ 613 00 Brno Czech Republic; Central European Institute of Technology Brno University of Technology Purkynova 123 CZ 612 00 Brno Czech Republic

Materials Research Centre Faculty of Chemistry Brno University of Technology Purkynova 118 612 00 Brno Czech Republic

University of Tasmania School of Physical Sciences and Australian Centre for Research on Separation Science Private Bag 75 Hobart 7001 Australia

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