Hemoglobin- and Hemin-catalyzed Transformation of 12L-hydroperoxy-5,8,10,14-eicosatetraenoic Acid

12L-Hydroperoxy-5,8,10,14-eicosatetraenoic acid (12L-HPETE) containing 2H at positions 5,6,8,9,11,12,14,15 was prepared during brief incubations of rat platelets with a mixture of [1-14C]arachidonic acid and 5,6,8,9,11,12,14,15-[ 2H8 ]arachidonic acid. The labelled 12L-HPETE was converted into a mixture of products, including 8- and 10-hydroxy-11,12- epoxyeicosatrienoic acids, during incubations in phosphate buffer containing bovine hemin. Hemoglobin could replace hemin in this reaction, which did not proceed in buffer alone. Mass spectral analysis showed these hydroxy epoxides to be identical to those previously identified from rat lung. These epoxides were hydrolyzed by a rat lung enzyme previously shown to contain epoxide hydratase activity. These results show that the hydroxy epoxides could be formed from 12L-HPETE nonenzymatically.