| Abstract
| - The OH-radical-induced mechanism of lipid peroxidation, involving hydrogen abstraction followed by O2addition, is explored using the kinetically corrected hybrid density functional MPWB1K in conjunction withthe MG3S basis set and a polarized continuum model to mimic the membrane interior. Using a small nonadienemodel of linoleic acid, it is found that hydrogen abstraction preferentially occurs at the mono-allylic methylenegroups at the ends of the conjugated segment rather than at the central bis-allylic carbon, in disagreementwith experimental data. Using a full linoleic acid, however, abstraction is correctly predicted to occur at thecentral carbon, giving a pentadienyl radical. The Gibbs free energy for abstraction at the central C11 is∼8 kcal/mol, compared to 9 kcal/mol at the end points (giving an allyl radical). Subsequent oxygen additionwill occur at one of the terminal atoms of the pentadienyl radical fragment, giving a localized peroxy radicaland a conjugated butadiene fragment, but is associated with rather high free energy barriers and low exergonicityat the CPCM-MPWB1K/MG3S level. The ZPE-corrected potential energy surfaces obtained without solventeffects, on the other hand, display considerably lower barriers and more exergonic reactions.
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