Horseradish peroxidase-catalyzed conversion of iodine to iodide in presence of EDTA and H2O2

Banerjee, R. K. ; De, S. K. ; Bose, A. K. ; Datta, A. G. (1986) Horseradish peroxidase-catalyzed conversion of iodine to iodide in presence of EDTA and H2O2 Journal of Biological Chemistry, 261 (23). pp. 10592-10597. ISSN 0021-9258

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Official URL: http://www.jbc.org/content/261/23/10592.short

Abstract

EDTA (4 mM) blocks the oxidation of iodide to I-3 (increase of extinction at 353 nm) by H2O2 catalyzed by horseradish peroxidase, which is reversed by the addition of an equimolar concentration of Zn2±. Addition of suboptimal concentration of EDTA (2 mM) not only decreases the rate of forward reaction of I-3 formation but also causes loss of extinction of the same when I-3 is generated. The loss of extinction of I-3 is proportional to the enzyme concentration and is blocked by azide, the inhibitor of the peroxidase. EDTA also causes bleaching of nonenzymatically formed I-3 (from iodide and H2O2) only in the presence of horseradish peroxidase, and the effect is reversed by the equimolar concentration of Zn2±. Both the bleaching of I-3 by EDTA and reversal of EDTA effect by Zn2± are sensitive to azide. The decrease of extinction of I-3 (formed by dissolving iodine in KI solution) is dependent on EDTA, H2O2, and horseradish peroxidase. Molecular iodine is also bleached but at a slower rate than I-3. Evidence is presented to show that this bleaching of I-3 is due to enzymatic conversion of I-3 to iodide in presence of EDTA and H2O2 and this involves pseudocatalatic degradation of H2O2 to O2.

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Source:Copyright of this article belongs to American Society for Biochemistry and Molecular Biology.
ID Code:23577
Deposited On:26 Nov 2010 08:37
Last Modified:17 May 2016 07:22

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