EXTRACTS OF PISUM-SATIVUM METABOLIZE PHOSPHOLIPID VIA A LIPOXYGENASE-LIKE MECHANISM

Extracts of Pisum sativum were found to oxidize unsaturated fatty acids esterified in complex lipids, in a reaction that appeared similar to lipoxygenase activity. Tocopherol stimulated this reaction. The enzyme had a complex substrate requirement; it was able to rapidly oxidize a crude phospholipid preparation, but was unable to attack pure phosphatides. The free fatty acid content of the lipid was very low and did not contribute significantly to the observed activity. There was no detectable phospholipase A activity in the enzyme preparations, precluding the release of fatty acids prior to oxidation. Dark-germinated seedlings contained at least three iso-forms of the enzyme. A single iso-form was present in the quiescent seed. It is concluded that Pisum sativum has an unusual lipoxygenase-like activity which requires further characterization.