J. Biol. Chem., Vol. 261, Issue 15, 6719-6724, May, 1986
Calcium-dependent oxidation of 5,8,11-icosatrienoic acid by the cyclooxygenase enzyme system
WJ Elliott, AR Morrison, H Sprecher and P Needleman
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.