Effect of coordination dissymmetry on the activity of homovalent dimanganese catalase mimics

SIGNORELLA, S. R.

Fortaleza

Congreso; VI Latin American Meeting on Biological Inorganic Chemistry; 2018

Sociedad Brasilera de Química - División Inorgánica

Manganese catalases (MnCATs) catalyze the disproportionation of H2O2 into innocuous H2O and O2 employing a diMn structural core [Mn2(μ-O2CR)(μ-O/OH/H2O)] (O2CR = Glu) that alternates between MnII2 and MnIII2 oxidation states during catalysis. In the active site, the two manganese ions differ in the number of exchangeable water ligands, with only one of the Mn subsites bound to a labile water molecule that is proposed to be the initial substrate binding site during catalysis [1]. This coordination dissymmetry around the two metal ions must be considered to reproduce the singularities of the biosite and could be the key toobtain efficient analogues of these enzymes able to act as H2O2 scavengers.Dinucleating ligands with a central alkoxo or phenoxo group (Figure) afford a scaffold to enhance co-operativity between the two Mn ions [2], and the introduction of asymmetry into this kind of ligands provides two different coordination compartments that can be used to mimic the bimetallic site with different environment around each metal centre.In this talk, the catalase activity of homovalent dimanganese complexes of dinucleating ligands is compared and the influence of the ligand asymmetry on the CAT activity of diMn mimics discussed.