Lipoxygenase metabolism of polyunsaturated fatty acids in oocytes of the frog Xenopus laevis.

Hawkins DJ, Brash AR
Arch Biochem Biophys. 1989 268 (2): 447-55

PMID: 2492416 · DOI:10.1016/0003-9861(89)90312-3

Recently, oocytes or eggs of two marine invertebrates have been found to metabolize arachidonic acid to specific monohydroxy products. These studies have prompted our examination of the oocytes of higher organisms. In the present study, oocytes of an amphibian, Xenopus laevis, were examined for their capacity to biosynthesize hydroxyeicosatetraenoic acids (HETEs) and related hydroxy fatty acids. Two hydroxyeicosanoids were formed during incubations of oocyte homogenates with [14C]arachidonic acid; their structures and stereochemistry were determined by high-pressure liquid chromatography, uv spectroscopy, and gas chromatography-mass spectrometry. The compounds were identified as 15(S)- and 12(S)-hydroxyeicosatetraenoic acids. The synthesis of the two HETEs was not blocked by a cyclooxygenase inhibitor, indomethacin (10 microM), or by prior exposure of the oocyte homogenates to carbon monoxide, an inhibitor of cytochrome P450. Furthermore, 12(S)- and 15(S)-hydroperoxyeicosatetraenoic acids were isolated from brief incubations of gel-filtered ammonium sulfate fraction of frog oocyte homogenates; isolation of the hydroperoxide is further support for the existence of 12(S)- and 15(S)-lipoxygenase activities in the oocytes of X. laevis. Other polyunsaturated acids, including C18.2, C18.3, C20.3, C20.5, and C22.6 were also substrates for the lipoxygenase, and in each case the major product was formed by omega 6 oxygenation.

MeSH Terms (14)

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid Animals Arachidonic Acid Arachidonic Acids Carbon Monoxide Chromatography, High Pressure Liquid Fatty Acids, Unsaturated Gas Chromatography-Mass Spectrometry Hydroxyeicosatetraenoic Acids Indomethacin Lipoxygenase Oocytes Oogenesis Xenopus laevis

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