STEREOCHEMICAL SPECIFICITY OF THE N‐9 LIPOXYGENASE OF FISH GILL

Stereospecificity of oxygen addition distinguishes lipoxygenase initiated lipid peroxidation from nonenzymatic autoxidation that produces a racemic mixture. Similarly, the positional and stereoconfiguration of lipoxygenase metabolites of un saturated fatty acids determine their precise physiological bioactivity. Teleost fish gills produce predominantly the 12 hydroxy derivative of arachidonic and eicosapentaenoic acids. Following reaction of arachidonic acid with fish gill lipoxygenase, 12‐hydroxyeicosatetraenoic acid (12‐HETE) was isolated using column chromatography and HPLC. Chiral phase HPLC revealed that the single 12(S) HETE isomer was produced by the enzyme. Proton NMR further confirmed the structure as identical to the 12(S) HETE produced in mammalian platelets and lungs.