Catechol Oxidase Lab Report

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The Importance of Cofactors for Enzyme Activity of Catechol Oxidase. Tiffany Connors, 2015. Functional Biology. Texas State University, San Marcos, TX 78666. Cofactors support enzymes in catalyzing reactions. By removing cofactors through the addition of chelators, the effect of cofactors on enzyme activity of potato catechol oxidase can be observed. This makes it possible to determine to what extent cofactors aid catechol oxidase in the oxidation of o-diphenols to o-quinones. For this experiment, four assays of catechol oxidase were prepared, including one which contained the chelator EDTA and another with PTU. A control assay which contained no chelators was also included. In order to observe the enzyme activity, a spectrophotometer was used.…show more content…
One of the key features of the enzyme’s structure is its dinuclear copper active site. The dicopper center catalyzes the oxidation of catechol through electron reduction of oxygen to water (Klabunde et al., 1998). In addition to Catechol Oxidase, there are two other know members of the 3 type copper proteins: hemocyanin and tyrosinase (Belle et al., 2006). Cofactors assist enzymes during catalytic reactions and help increase the rate of enzyme activity. Metal ions, such as copper, commonly serve as cofactors. These ions provide a strongly electrophilic center, which aids in electron reduction (Broderick, 2001). Cofactors can be removed by using a chelator that selectively binds to the cofactor. For this experiment, two chelators were selected. The chelator ethylene diamine tetra acetic acid (EDTA) removes Mg2+ and Ca2+. The chelator phenylthiourea (PTU) selectively removes Cu 2+. The purpose of this experiment was to demonstrate the importance of cofactors for enzyme activity. Through the use of a spectrophotometer, the enzyme activity of potato catechol oxidase can be observed. It was predicted that the addition of chelators to the assay would decrease the rate of enzyme activity. Materials and

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