David M Freire1, Debora Beeri1, Kristof Pota1, Hannah M Johnston1, Philip Palacios2, Brad S Pierce3, Benjamin D Sherman1, Kayla N Green1. 1. Department of Chemistry and Biochemistry, Texas Christian University, 2950 W.Bowie, Fort Worth, TX 76129, United States. 2. Department of Chemistry and Biochemistry, The University of Texas at Arlington, 700 Planetarium Place, Arlington, TX 76019. 3. Department of Chemistry and Biochemistry, University of Alabama, 250 Hackberry Lane, Box 870336 Tuscaloosa, AL 35487.
Abstract
The catalase family of enzymes, which include a variety with a binuclear manganese active site, mitigate the risk from reactive oxygen species by facilitating the disproportionation of hydrogen peroxide into molecular oxygen and water. In this work, hydrogen peroxide disproportionation using complexes formed between manganese and cyclen or pyclen were investigated due to the spectroscopic similarities with the native MnCAT enzyme. Potentiometric titrations were used to construct speciation diagrams that identify the manganese complex compositions at different pH values. Each complex behaves as a functional mimic of catalase enzymes. UV-visible spectroscopic investigations of the H2O2 decomposition reaction yielded information about the structure of the initial catalyst and intermediates that include monomeric and dimeric species. The results indicate that rigidity imparted by the pyridine ring of pyclen is a key factor in increased TON and TOF values measured compared to cyclen.
The catalase family of enzymes, which include a variety with a binuclearn class="Chemical">manganese active site, mitigate the risk from reactive oxygen species by facilitating the disproportionation of hydrogen peroxide into molecular oxygen and water. In this work, hydrogen peroxide disproportionation using complexes formed between manganese and cyclen or pyclen were investigated due to the spectroscopic similarities with the native MnCAT enzyme. Potentiometric titrations were used to construct speciation diagrams that identify the manganese complex compositions at different pH values. Each complex behaves as a functional mimic of catalase enzymes. UV-visible spectroscopic investigations of the H2O2 decomposition reaction yielded information about the structure of the initial catalyst and intermediates that include monomeric and dimeric species. The results indicate that rigidity imparted by the pyridine ring of pyclen is a key factor in increased TON and TOF values measured compared to cyclen.
Authors: Marta Czerska; Karolina Mikołajewska; Marek Zieliński; Jolanta Gromadzińska; Wojciech Wąsowicz Journal: Med Pr Date: 2015 Impact factor: 0.760
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