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The horseradish peroxidase-catalyzed oxidation of 3,5,3',5'-tetramethylbenzidine. Free radical and charge-transfer complex intermediates.

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Josephy, P D, Eling, T, Mason, R P·1982·Journal of Biological Chemistry

Abstract

Benzidine and related compounds are well known substrates for horseradish peroxidase/H2O2 oxidation. Typically, two different colored products are formed. In this paper, we study the oxidation of 3,5,3',5'-tetramethylbenzidine. The first colored product is a blue charge-transfer complex of the parent diamine and the diimine oxidation product. This species exists in rapid equilibrium with the radical cation. The radical was observed by ESR spectroscopy, and hyperfine splitting constants were determined. Addition of equimolar hydrogen peroxide yields the yellow diimine, which is stable at acid pH. At less than equimolar peroxide, all four species (diamine, radical cation, charge-transfer complex, and diimine) exist in equilibrium. A theoretical analysis of this redox system is presented, including a determination of the extinction coefficients and equilibrium constant for the nonradical species.

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Metadata

Authors
Josephy, P. D., Eling, T., & Mason, R. P.
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
1982-04
Volume
257
Issue
7
Pages
3669-3675
ISSN
0021-9258 (ISSN-L)
OpenAlex
W1649220013
Cited by
966
References
0
FWCI
17.07
Type
journal article
Language
en
Open access
hybrid

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CoChat. (2026). Citation check: The horseradish peroxidase-catalyzed oxidation of 3,5,3',5'-tetramethylbenzidine. Free radical and charge-transfer complex intermediates. https://app.cochat.ai/papers/10.1016/s0021-9258(18)34832-4
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Josephy, P. D., Eling, T., & Mason, R. P. (1982). The horseradish peroxidase-catalyzed oxidation of 3,5,3',5'-tetramethylbenzidine. Free radical and charge-transfer complex intermediates. Journal of Biological Chemistry. https://doi.org/10.1016/s0021-9258(18)34832-4

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