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Title: DT-diaphorase-catalyzed two-electron reduction of various p-benzoquinone- and 1,4-naphthoquinone epoxides

Abstract

The oxidation of various quinones by H{sub 2}O{sub 2} results in quinone epoxide formation. The yield of epoxidation is inversely related to the degree of methyl substitution of the quinone and seems not to be dependent on the redox potential of the quinones studied. The following order of H{sub 2}O{sub 2}-mediated epoxidation of quinones was found: p-benzoquinone greater than or equal to 1,4-naphthoquinone greater than 2-methyl-p-benzoquinone greater than 2,6-dimethyl-p-benzoquinone greater than or equal to 2-methyl-1,4-naphthoquinone greater than 2,3-dimethyl-1,4-naphthoquinone. DT-Diaphorase reduces several quinone epoxides at different rates. The rate of quinone epoxide reduction cannot be related to either the redox potential of the quinone epoxide (as reflected by the half-wave potential calculated from the corresponding hydrodynamic voltamograms) or the degree of substitution of the quinone epoxide. It appears, however, that a quinone epoxide redox potential more negative than -0.5 to -0.6 volts settles a threshold for the electron transfer reaction. This does not exclude that specificity requirements, i.e. the formation of the quinone epoxide substrate-enzyme complex may chiefly determine the rate of reduction of quinone epoxides by DT-diaphorase. DT-diaphorase-catalyzed two-electron transfer to quinone epoxides--resulting in epoxide ring opening--yields 2-OH-p-benzohydroquinone or 2-OH-1,4-naphthohydroquinone products. These hydroxy-derivatives show a higher rate of autoxidation thanmore » do the parent hydroquinones lacking the OH substituent.« less

Authors:
; ; ; ;  [1]
  1. Univ. of Linkoeping (Sweden)
Publication Date:
OSTI Identifier:
5668484
Resource Type:
Journal Article
Journal Name:
Free Radical Biology and Medicine; (USA)
Additional Journal Information:
Journal Volume: 5:3; Journal ID: ISSN 0891-5849
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; HYDROGEN PEROXIDE; BIOLOGICAL EFFECTS; QUINONES; METABOLISM; ELECTRON TRANSFER; EPOXIDES; REDOX POTENTIAL; REDOX REACTIONS; SPECIFICITY; AROMATICS; CHEMICAL REACTIONS; HYDROGEN COMPOUNDS; ORGANIC COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; OXYGEN COMPOUNDS; PEROXIDES; 560300* - Chemicals Metabolism & Toxicology

Citation Formats

Brunmark, A, Cadenas, E, Segura-Aguilar, J, Lind, C, and Ernster, L. DT-diaphorase-catalyzed two-electron reduction of various p-benzoquinone- and 1,4-naphthoquinone epoxides. United States: N. p., 1988. Web. doi:10.1016/0891-5849(88)90076-7.
Brunmark, A, Cadenas, E, Segura-Aguilar, J, Lind, C, & Ernster, L. DT-diaphorase-catalyzed two-electron reduction of various p-benzoquinone- and 1,4-naphthoquinone epoxides. United States. https://doi.org/10.1016/0891-5849(88)90076-7
Brunmark, A, Cadenas, E, Segura-Aguilar, J, Lind, C, and Ernster, L. Fri . "DT-diaphorase-catalyzed two-electron reduction of various p-benzoquinone- and 1,4-naphthoquinone epoxides". United States. https://doi.org/10.1016/0891-5849(88)90076-7.
@article{osti_5668484,
title = {DT-diaphorase-catalyzed two-electron reduction of various p-benzoquinone- and 1,4-naphthoquinone epoxides},
author = {Brunmark, A and Cadenas, E and Segura-Aguilar, J and Lind, C and Ernster, L},
abstractNote = {The oxidation of various quinones by H{sub 2}O{sub 2} results in quinone epoxide formation. The yield of epoxidation is inversely related to the degree of methyl substitution of the quinone and seems not to be dependent on the redox potential of the quinones studied. The following order of H{sub 2}O{sub 2}-mediated epoxidation of quinones was found: p-benzoquinone greater than or equal to 1,4-naphthoquinone greater than 2-methyl-p-benzoquinone greater than 2,6-dimethyl-p-benzoquinone greater than or equal to 2-methyl-1,4-naphthoquinone greater than 2,3-dimethyl-1,4-naphthoquinone. DT-Diaphorase reduces several quinone epoxides at different rates. The rate of quinone epoxide reduction cannot be related to either the redox potential of the quinone epoxide (as reflected by the half-wave potential calculated from the corresponding hydrodynamic voltamograms) or the degree of substitution of the quinone epoxide. It appears, however, that a quinone epoxide redox potential more negative than -0.5 to -0.6 volts settles a threshold for the electron transfer reaction. This does not exclude that specificity requirements, i.e. the formation of the quinone epoxide substrate-enzyme complex may chiefly determine the rate of reduction of quinone epoxides by DT-diaphorase. DT-diaphorase-catalyzed two-electron transfer to quinone epoxides--resulting in epoxide ring opening--yields 2-OH-p-benzohydroquinone or 2-OH-1,4-naphthohydroquinone products. These hydroxy-derivatives show a higher rate of autoxidation than do the parent hydroquinones lacking the OH substituent.},
doi = {10.1016/0891-5849(88)90076-7},
url = {https://www.osti.gov/biblio/5668484}, journal = {Free Radical Biology and Medicine; (USA)},
issn = {0891-5849},
number = ,
volume = 5:3,
place = {United States},
year = {1988},
month = {1}
}