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Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature
Recently, increasing attention has been paid to quantum mechanical behavior in biology. In this study, we investigated the involvement of quantum mechanical tunneling in the hydrogen-transfer reaction from Trolox, a water-soluble analog of vitamin E (α-tocopherol), to 2,2-diphenyl-1-picrylhydrazyl r...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8750123/ https://www.ncbi.nlm.nih.gov/pubmed/34943069 http://dx.doi.org/10.3390/antiox10121966 |
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author | Nakanishi, Ikuo Shoji, Yoshimi Ohkubo, Kei Fukuzumi, Shunichi |
author_facet | Nakanishi, Ikuo Shoji, Yoshimi Ohkubo, Kei Fukuzumi, Shunichi |
author_sort | Nakanishi, Ikuo |
collection | PubMed |
description | Recently, increasing attention has been paid to quantum mechanical behavior in biology. In this study, we investigated the involvement of quantum mechanical tunneling in the hydrogen-transfer reaction from Trolox, a water-soluble analog of vitamin E (α-tocopherol), to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(•)) in a phosphate buffer solution (0.05 M, pH 7.0). DPPH(•) was used as a reactivity model of reactive oxygen species and solubilized in water using β-cyclodextrin (β-CD). The second-order rate constants, k(H) and k(D), in 0.05 M phosphate buffer solutions prepared with H(2)O (pH 7.0) and D(2)O (pD 7.0), respectively, were determined for the reaction between Trolox and DPPH(•), using a stopped-flow technique at various temperatures (283–303 K). Large kinetic isotope effects (KIE, k(H)/k(D)) were observed for the hydrogen-transfer reaction from Trolox to the β-CD-solubilized DPPH(•) in the whole temperature range. The isotopic ratio of the Arrhenius prefactor (A(H)/A(D) = 0.003), as well as the isotopic difference in the activation energies (19 kJ mol(−1)), indicated that quantum mechanical tunneling plays a role in the reaction. |
format | Online Article Text |
id | pubmed-8750123 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-87501232022-01-12 Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature Nakanishi, Ikuo Shoji, Yoshimi Ohkubo, Kei Fukuzumi, Shunichi Antioxidants (Basel) Communication Recently, increasing attention has been paid to quantum mechanical behavior in biology. In this study, we investigated the involvement of quantum mechanical tunneling in the hydrogen-transfer reaction from Trolox, a water-soluble analog of vitamin E (α-tocopherol), to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(•)) in a phosphate buffer solution (0.05 M, pH 7.0). DPPH(•) was used as a reactivity model of reactive oxygen species and solubilized in water using β-cyclodextrin (β-CD). The second-order rate constants, k(H) and k(D), in 0.05 M phosphate buffer solutions prepared with H(2)O (pH 7.0) and D(2)O (pD 7.0), respectively, were determined for the reaction between Trolox and DPPH(•), using a stopped-flow technique at various temperatures (283–303 K). Large kinetic isotope effects (KIE, k(H)/k(D)) were observed for the hydrogen-transfer reaction from Trolox to the β-CD-solubilized DPPH(•) in the whole temperature range. The isotopic ratio of the Arrhenius prefactor (A(H)/A(D) = 0.003), as well as the isotopic difference in the activation energies (19 kJ mol(−1)), indicated that quantum mechanical tunneling plays a role in the reaction. MDPI 2021-12-08 /pmc/articles/PMC8750123/ /pubmed/34943069 http://dx.doi.org/10.3390/antiox10121966 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Communication Nakanishi, Ikuo Shoji, Yoshimi Ohkubo, Kei Fukuzumi, Shunichi Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature |
title | Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature |
title_full | Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature |
title_fullStr | Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature |
title_full_unstemmed | Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature |
title_short | Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature |
title_sort | tunneling in the hydrogen-transfer reaction from a vitamin e analog to an inclusion complex of 2,2-diphenyl-1-picrylhydrazyl radical with β-cyclodextrin in an aqueous buffer solution at ambient temperature |
topic | Communication |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8750123/ https://www.ncbi.nlm.nih.gov/pubmed/34943069 http://dx.doi.org/10.3390/antiox10121966 |
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