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Is the presence of dicarboxylic acids required in the MnP cycle?: Study of Mn3+ stability by cyclic voltammetry

Paper ID Volume ID Publish Year Pages File Format Full-Text
18605 42727 2007 6 PDF Available
Title
Is the presence of dicarboxylic acids required in the MnP cycle?: Study of Mn3+ stability by cyclic voltammetry
Abstract

The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxylic acids to chelate and stabilize the oxidized and very unstable Mn3+, which is responsible for the final substrate oxidation. However, the enzymatic degradation of an azo dye, Orange II, was successfully performed in the absence of any carboxylic acid. To analyze this possible discrepancy, the effect of the presence of several organic acids (oxalic, malonic, tartaric and citric acids) was studied on the kinetics and the extension of the degradation of Orange II. The Mn3+ chelating strength, an important factor that should influence the efficiency of the degradation, was determined for the different organic acids and the dye by cyclic voltammetry. Oxalic acid was determined to be the best chelator, followed by malonic, tartaric and finally, citric acid. Orange II was shown to act as a chelator, since the hydroxyl and sulfonic groups allow a stabilized complex to be formed, avoiding the use of any dicarboxylic acid. This distinctive property could be extended to other molecules with a potential binding capacity.

Keywords
Mn3+ stabilization; Cyclic voltammetry; Manganese peroxidase; Carboxylic acids; Orange II; Chelation
First Page Preview
Is the presence of dicarboxylic acids required in the MnP cycle?: Study of Mn3+ stability by cyclic voltammetry
Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 42, Issue 1, 3 December 2007, Pages 70–75
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering