@article{oai:repo.qst.go.jp:00084655,
 author = {Nakanishi, Ikuo and Shoji, Yoshimi and Ohkubo, Kei and Fukuzumi, Shunichi and Ikuo, Nakanishi and Yoshimi, Shoji and Kei, Ohkubo},
 issue = {12},
 journal = {Antioxidants},
 month = {Dec},
 note = {Recently, increasing attention has been paid to the quantum mechanical behavior in biology. In this study, we have investigated the involvement of the 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•) by 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 by β-cyclodextrin (β-CD). The second-order rate constants, kH and kD, in 0.05 M phosphate buffer solutions prepared with H2O (pH 7.0) and D2O (pD 7.0), respectively, were determined for the reaction between Trolox and DPPH• by a stopped-flow technique at various temperatures (283–303 K). Large kinetic isotope effects (KIE, kH/kD) 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 (AH/AD = 0.003) as well as the isotopic difference in the activation energies (19 kJ mol–1) indicates that quantum mechanical tunneling plays a role in the reaction.},
 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 Solutions at Ambient Temperature},
 volume = {10},
 year = {2021}
}