title: Calcium-dependent oxidation of 5,8,11-icosatrienoic acid by the cyclooxygenase enzyme system.
abstract: Mead (5,8,11-icosatrienoic) acid was found to be metabolized by the cyclooxygenase enzyme system of ram seminal vesicle microsomes in a calcium-dependent manner. Although the enzyme converted Mead acid to products more slowly and less completely than the isomeric 8,11,14-icosatrienoic acid, both oxidations were inhibitable by indomethacin. Experiments using purified cyclooxygenase confirmed the participation of this enzyme system in the calcium-dependent oxidation. The products of the oxidation were separated by high performance liquid chromatography and analyzed by ultraviolet and gas chromatography-mass spectrometry. The spectra obtained were consistent with the products having the structures 13-hydroxy-5,8,11-icosatrienoate (the major product), 11-hydroxy-5,8,12-icosatrienoate, 9-hydroxy-5,7,11-icosatrienoate, and two isomeric 8,11-dihydroxy-5,9,12-icosatrienoates. No prostaglandin-like, cyclized products could be identified. This report is only the second to illustrate a calcium-dependent oxidation of a polyunsaturated fatty acid by a cyclooxygenase enzyme system and further extends the metabolic potential of Mead acid.
mesh_terms: D015126:8,11,14-Eicosatrienoic Acid / Q000378:metabolism* / Q000031:analogs & derivatives; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D007536:Isomerism; D008297:Male; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D012669:Seminal Vesicles / Q000201:enzymology; D012756:Sheep
chemical_list: D002250:Carbon Radioisotopes; D005231:Fatty Acids, Unsaturated; D011451:Prostaglandin-Endoperoxide Synthases; D015126:8,11,14-Eicosatrienoic Acid; C010944:mead acid; D002118:Calcium