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Unusual Kinetic Isotope Effects of Deuterium Reinforced Polyunsaturated Fatty Acids in Tocopherol-Mediated Free Radical Chain Oxidations

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journal contribution
posted on 2014-01-22, 00:00 authored by Connor R. Lamberson, Libin Xu, Hubert Muchalski, J. Rafael Montenegro-Burke, Vadim V. Shmanai, Andrei V. Bekish, John A. McLean, Catherine F. Clarke, Mikhail S. Shchepinov, Ned A. Porter
Substitution of −CD2– at the reactive centers of linoleic and linolenic acids reduces the rate of abstraction of D by a tocopheryl radical by as much as 36-fold, compared to the abstraction of H from a corresponding −CH2– center. This H atom transfer reaction is the rate-determining step in the tocopherol-mediated peroxidation of lipids in human low-density lipoproteins, a process that has been linked to coronary artery disease. The unanticipated large kinetic isotope effects reported here for the tocopherol-mediated oxidation of linoleic and linolenic acids and esters suggests that tunneling makes this process favorable.