Formation of 8,11,12-trihydroxyeicosatrienoic acid by a rat lung high-speed supernatant fraction.

An enzyme was found in the high-speed (100 000 x g) supernatant fraction of a rat lung homogenate which catalysed the conversion of arachidonic acid into 8,11,12-trihydroxyeicosatrienoic acid. The isomeric 8,9,12-triol was not detected. The structure of the isolated product was confirmed by mass spectrometric analysis of the methyl ester t-butyldimethylsilyl ether derivative. These results indicate that formation of both positional isomers is carried out by separate enzymes, the distributions of which are not restricted to platelets.