J. Lipid Res.
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Originally published In Press as doi:10.1194/jlr.M700055-JLR200 on March 2, 2007

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Journal of Lipid Research, Vol. 48, 1371-1377, June 2007
Copyright © 2007 by American Society for Biochemistry and Molecular Biology

Feedback activation of ferrous 5-lipoxygenase during leukotriene synthesis by coexisting linoleic acid

Tokuko Takajo*, Kazunori Tsuchida*, Koichi Ueno{dagger} and Ichiro Koshiishi1,*

* Nihon Pharmaceutical University, 10281 Komuro, Ina-machi, Kita-Adachi-gun, Saitama, 362-0806 Japan
{dagger} Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan

Published, JLR Papers in Press, March 2, 2007.

1 To whom correspondence should be addressed. e-mail: ikoshi{at}nichiyaku.ac.jp

Ferrous lipoxygenases seem to be activated through a feedback control mechanism via FA hydroperoxides generated from PUFAs by partially existing ferric lipoxygenases. However, during leukotriene synthesis, feedback activation of ferrous 5-lipoxygenase in the presence of arachidonic acid (AA) was not observed. In the present study, we examined the feedback activation of ferrous 5-lipoxygenase in the 5-lipoxygenase/AA system in the presence of linoleic aicd (LA), which is a predominant component of membrane phospholipids. When potato 5-lipoxygenase was incubated with AA and LA in the presence of nitroxyl radical, 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrroline-N-oxyl (Cm{Delta}P), one-electron redox cycle reaction between ferric and ferrous 5-lipoxygenase was detected. For each revolution of the cycle, one molecule of PUFA and one molecule of its hydroperoxide were converted into PUFA-allyl radical-Cm{Delta}P adduct ([PUFA–H]·-Cm{Delta}P) and PUFA-epoxyallyl radical-Cm{Delta}P adduct ([PUFA–H+O]·-Cm{Delta}P), respectively. The ratios, [AA–H]·-Cm{Delta}P/[LA–H]·-Cm{Delta}P and [AA–H+O]·-Cm{Delta}P/[LA–H+O]·-Cm{Delta}P, were estimated to be 1.7 and 0.13, respectively. These facts indicate that ferrous 5-lipoxygenase is activated through feedback control in the presence of LA, and that resulting ferric 5-lipoxygenase catalyzes the stoichiometric synthesis of leukotrienes from AA. In conclusion, the biosynthesis of leukotrienes is remarkably efficient.

Supplementary key words isozyme • pseudoperoxidase reaction • hydroperoxides

Abbreviations: AA, arachidonic acid; Cm{Delta}P, 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrroline-N-oxyl; FA, fatty acid; HpETE, hydroperoxyeicosatetraenoic acid; HpODE, hydroperoxyoctadecadienoic acid; LA, linoleic acid; LC, liquid chromatography; MS/MS, tandem mass spectrometry; PIS, precursor ion scanning; PUFA, polyunsaturated fatty acid; XIC, extracted ion chromatogram


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Copyright © 2007 by the American Society for Biochemistry and Molecular Biology.