Unsaturated fatty acid-dependent oxidation of epinephrine in homogenates of the gorgonian, Pseudoplexaura porosa

A novel epinephrine oxidation system in homogenates of the gorgonian Pseudoplexaura porosa was discovered. The enzymatic reaction required an unsaturated fatty acid and molecular oxygen or hydrogen peroxide. Diphenylisobenzofuran was also oxidized by Ps. porosa homogenates in the presence of an unsaturated fatty acid. Hydroxyl radical and superoxide anion did not appear to be involved in either of these oxidative reactions. The production of lipid hydroperoxides was not necessary for epinephrine oxidation and, with the exception of arachidonic acid, lipid hydroperoxide production did not occur. Evidence is presented for the involvement of singlet oxygen or a similar activated oxygen intermediate in the reactions, and a possible mechanism was proposed. The use of arachidonate-dependent epinephrine oxidation as a measure of prostaglandin synthetase activity is criticized.