Jisaka Mitsuo, Iwanaga Chitose, Takahashi Nobuyuki, Goto Tsuyoshi, Kawada Teruo, Yamamoto Tatsuyuki, Ikeda Izumi, Nishimura Kohji, Nagaya Tsutomu, Fushiki Tohru, Yokota Kazushige
Department of Life Science and Biotechnology, Shimane University, Matsue, Shimane 690-8504, Japan.
Biochem Biophys Res Commun. 2005 Dec 9;338(1):136-43. doi: 10.1016/j.bbrc.2005.08.029. Epub 2005 Aug 15.
Mouse 8S-lipoxygenase (8-LOX) metabolizes arachidonic acid (AA) specifically to 8S-hydroperoxyeicosatetraenoic acid (8S-HPETE), which will be readily reduced under physiological circumstances to 8S-hydroxyeicosatetraenoic acid (8S-HETE), a natural agonist of peroxisome proliferator-activated receptor alpha (PPAR alpha). Here, we investigated whether 8-LOX could further oxygenate AA and whether the products could activate PPARs. The purified recombinant 8-LOX converted AA exclusively to 8S-HPETE and then to (8S,15S)-dihydroperoxy-5Z,9E,11Z,13E-eicosatetraenoic acid (8S,15S-diHPETE). The kcat/Km values for 8S-HPETE and AA were 3.3x10(3) and 2.7x10(4) M(-1) s(-1), respectively. 8-LOX also dioxygenated 8S-HETE and 15S-H(P)ETE specifically to the corresponding 8S,15S-disubstituted derivatives. By contrast, 15-LOX-2, a human homologue of 8-LOX, produced 8S,15S-diH(P)ETE from 8S-H(P)ETE but not from AA nor 15S-H(P)ETE. 8S,15S-diHETE activated PPAR alpha more strongly than 8S-HETE did. The present results suggest that 8S,15S-diH(P)ETE as well as 8S-H(P)ETE would contribute to the physiological function of 8-LOX and also that 8-LOX can function as a potential 15-LOX.
小鼠8S-脂氧合酶（8-LOX）将花生四烯酸（AA）特异性代谢为8S-氢过氧化二十碳四烯酸（8S-HPETE），在生理条件下8S-HPETE会迅速还原为8S-羟基二十碳四烯酸（8S-HETE），后者是过氧化物酶体增殖物激活受体α（PPARα）的天然激动剂。在此，我们研究了8-LOX是否能进一步氧化AA以及其产物是否能激活PPARs。纯化的重组8-LOX仅将AA转化为8S-HPETE，然后再转化为（8S,15S）-二氢过氧化-5Z,9E,11Z,13E-二十碳四烯酸（8S,15S-二HPETE）。8S-HPETE和AA的kcat/Km值分别为3.3×10³和2.7×10⁴ M⁻¹ s⁻¹。8-LOX还将8S-HETE和15S-H（P）ETE特异性双加氧化为相应的8S,15S-二取代衍生物。相比之下，8-LOX的人类同源物15-LOX-2可从8S-H（P）ETE生成8S,15S-二H（P）ETE，但不能从AA或15S-H（P）ETE生成。8S,15S-二HETE比8S-HETE更强烈地激活PPARα。目前的结果表明，8S,15S-二H（P）ETE以及8S-H（P）ETE可能参与8-LOX的生理功能，并且8-LOX可能具有潜在的15-LOX功能。
