Substrate Specificity of Mackerel Flesh Lipopolygenase

A lipoxygenase enzyme was found in mackerel flesh which oxidized linoleic and docosahexaenoic acids more efficiently than eicosapentaenoic or linolenic acids. Activity was inhibited by esculetin and was destroyed by boiling; 40% of activity was lost after incubation at 50°C for 10 min, and 80% after incubation at 60°C. Ultrafiltration of the crude enzyme extract with a molecular weight cut off of 10 KD showed the activity came predominantly from the higher molecular weight fraction. Results support the hypothesis that there are several different lipoxygenases located in different fish tissues.