Direct ESR detection of pentadienyl radicals and peroxyl radicals in lipid peroxidation: Mechanistic insight into regioselective oxygenation in lipoxygenases

Hironori Kitaguchi, Kei Ohkubo, Seiji Ogo, Shunichi Fukuzumi

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

Well-resolved ESR spectra of free pentadienyl radicals have been observed under photoirradiation of di-tert-butylperoxide (ButOOBut) and polyunsaturated fatty acids in the absence of O2, allowing us to determine the hfc values. The hfc values of linoleyl radical indicate that the spin density is the largest at the C-11 position. The linoleyl radical is readily trapped by O2 to produce the peroxyl radical (11-HPO ) in which O2 is added mainly at the C-11 position of the pentadienyl radical as indicated by the comparison of the ESR spectra of peroxyl radicals derived from linoleic acid and [11,11-2H 2]linoleic acid. The peroxyl radical (13-HPO), which is initially formed by the hydrogen abstraction from 13-(S)-hydroperoxy-9(Z), 11(E)-octadecadienoic acid (13-HPOD) by ButO, is found to isomerize to 11-HPO via removal of O2 from 13-HPO and addition of O2 to linoleyl radical to produce 11-HPO. This finding supports an idea of O2 entering via a specific protein channel, which determines the stereo- and regiochemistry of the biradical combination between O2 and linoleyl radical in lipoxygenases.

Original languageEnglish
Pages (from-to)6605-6609
Number of pages5
JournalJournal of the American Chemical Society
Volume127
Issue number18
DOIs
Publication statusPublished - May 11 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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