Synthesis, characterization, hydrolase and catecholase activity of a dinuclear iron(III) complex: Catalytic promiscuity Tiago P. Camargo a , Fernanda F. Maia a , Cláudia Chaves a , Bernardo de Souza a , Adailton J. Bortoluzzi a , Nathalia Castilho b , Tiago Bortolotto b , Hernán Terenzi b , Eduardo E. Castellano c , Wolfgang Haase d , Zbigniew Tomkowicz e , Rosely A. Peralta a, ⁎, Ademir Neves a, ⁎⁎ a Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil b Centro de Biologia Molecular Estrutural, Departamento de Bioquímica, Universidade Federal de Santa Catarina, Florianópolis 88040-900, Brazil c Instituto de Física, Universidade de São Paulo, 13360-979 São Carlos, SP, Brazil d Institut für Physikalishe Chemie, Technische Universität Darmstadt, Petersenstraße 20, D-64287 Darmstadt, Germany e Institute of Physics, Reymonta 4, Jagiellonian University, PL-30-059 Krakow, Poland abstract article info Article history: Received 6 November 2014 Received in revised form 24 February 2015 Accepted 24 February 2015 Available online 5 March 2015 Keywords: Dinuclear iron(III) complex Catalytic promiscuity DNA cleavage Herein, we report the synthesis and characterization of the new di-iron(III) complex [(bbpmp)(H 2 O)(Cl)Fe III (μ-O phenoxo )Fe III (H 2 O)Cl)]Cl (1), with the symmetrical ligand 2,6-bis{[(2-hydroxybenzyl)(pyridin-2-yl) methylamino]methyl}-4-methylphenol (H 3 bbpmp). Complexes 2 with the unsymmetrical ligand H 2 bpbpmp — {2-[[(2-hydroxybenzyl)(2-pyridylmethyl)]aminomethyl]-6-bis(pyridylmethyl) aminomethyl}-4-methylphenol and 3 with the ligand L 1 = 4,11-dimethyl-1,8-bis{2-[N-(di-2-pyridylmethyl)amino]ethyl}cyclam were included for comparison purposes. Complex 1 was characterized through elemental analysis, X-ray crystallography, magnetochemistry, electronic spectroscopy, electrochemistry, mass spectrometry and potentiometric titration. The magnetic data show a very weak antiferromagnetic coupling between the two iron centers of the dinuclear complex 1 (J = -0.29 cm -1 ). Due to the presence of labile coordination sites in both iron centers the hydrolysis of both the diester model substrate 2,4-BDNPP and DNA was studied in detail. Complex 1 was also able to catalyze the oxidation of the substrate 3,5-di-tert-butylcatechol (3,5-DTBC) to give the corresponding quinone, and thus it can be considered as a catalytically promiscuous system. © 2015 Elsevier Inc. All rights reserved. 1. Introduction Iron containing enzymes have several vital functions in living sys- tems since they participate in many different types of reactions such as electron transfer, hydrolysis of phosphate esters and gene expression. They are extremely versatile and for this reason, there is a huge interest in the commercial application of these systems in biotechnology. How- ever, their structures, mechanisms and functions are not yet fully under- stood [1]. In general, enzymes are known for their high efficiency and specificity but, in many cases, a single catalytic site can catalyze more than one chemical transformation. This is called catalytic promiscuity and this is a phenomenon reasonably well described for biological systems. For example, it has been shown that an aminopeptidase obtained from Streptomyces griseus containing a dinuclear Cu II active site is capable of hydrolyzing phosphate esters and peptides, but it also oxidizes catechols with activity close to that of the native enzyme [2]. It has been proposed that this enzyme and its possible variants could serve as unique dinuclear systems to provide further insight into the structure–mechanism correla- tions in metal-centered hydrolytic and oxidation chemistry. Catechol oxidase (CO) is a dinuclear copper enzyme that catalyzes the two-electron-transfer reaction during the oxidation of a wide range of catechols to the corresponding o-quinones by O 2 in a process known as catecholase activity, while hydrolases belong to a class of metalloenzymes (metal = Zn, Cu, Fe, Mn, Ca) that catalyze the hydroly- sis of several type of substrates including phosphate esters, peptides and nuclei acids [3]. A generic scheme of both reactions is shown in Scheme 1. In fact such dinuclear hydrolytic and oxidative metalloenzymes have been used as appropriate starting points in the development of specific classes of synthetic metal complexes, known as synthetic hydrolases and synthetic catechol oxidases. During the last two de- cades extensive studies on synthetic model systems have been re- ported, aiming to mimic the structural and/or functional properties of these metalloenzymes, such as metal–metal distances, redox potentials, and geometry around each metal center, with the presence of labile sites essential for binding of the substrate and/or available nucleophiles Journal of Inorganic Biochemistry 146 (2015) 77–88 ⁎ Corresponding author. Tel.: +55 48 37213627. ⁎⁎ Corresponding author. Tel.: +55 48 37213605. E-mail addresses: rosely.peralta@ufsc.br (R.A. Peralta), ademir.neves@ufsc.br (A. Neves). http://dx.doi.org/10.1016/j.jinorgbio.2015.02.017 0162-0134/© 2015 Elsevier Inc. All rights reserved. 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