Oxygenation of 5,8,11-eicosatrienoic acid by prostaglandin H synthase-2 of ovine placental cotyledons: isolation of 13-hydroxy-5,8,11-eicosatrienoic and 11-hydroxy-5,8,12-eicosatrienoic acids.
Prostaglandin H synthase-1 of ram vesicular glands metabolises 5,8,11-eicosatrienoic (Mead) acid to 13R-hydroxy-5,8,11-eicosatrienoic and to 11R-hydroxy-5,8,12-eicosatrienoic in a 5:1 ratio. We wanted to determine the metabolism of this fatty acid by prostaglandin H synthase-2. Western blot showed that microsomes of sheep and rabbit placental cotyledons contained prostaglandin H synthase-2, while prostaglandin H synthase-1 could not be detected. Microsomes of sheep cotyledons metabolised [1-14C]5,8,11-eicosatrienoic acid to many polar metabolites and diclofenac (0.05 mM) inhibited the biosynthesis. The two major metabolites were identified as 13-hydroxy-5,8,11-eicosatrienoic and 11-hydroxy-5,8,12-eicosatrienoic acids. They were formed in a ratio of 3:2, which was not changed by aspirin (2 mM). 5,8,11-Eicosatrienoic acid is likely oxygenated by removal of the pro-S hydrogen at C-13 and insertion of molecular oxygen at either C-13 or C-11, which is followed by reduction of the peroxy derivatives to 13-hydroxy-5,8,11-eicosatrienoic and 11-hydroxy-5,8,12-eicosatrienoic acids, respectively. Prostaglandin H synthase-1 and -2 oxygenate 5,8,11-eicosatrienoic acid only slowly compared with arachidonic acid.
Oliw
E H
EH
Department of Pharmaceutical Biosciences. Uppsala University Biomedical Center.
Hörnsten
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Sprecher
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D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D005260:Female; D006893:Hydroxyeicosatetraenoic Acids / Q000032:analysis / Q000096:biosynthesis*; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D008861:Microsomes / Q000201:enzymology; D010920:Placenta / Q000201:enzymology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D012669:Seminal Vesicles / Q000201:enzymology; D012756:Sheep
C106026:11-hydroxy-5,8,12-eicosatrienoic acid; C106027:13-hydroxy-5,8,11-eicosatrienoic acid; D006893:Hydroxyeicosatetraenoic Acids; D007527:Isoenzymes; D008565:Membrane Proteins; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat; D015126:8,11,14-Eicosatrienoic Acid; C010944:mead acid