Characterization of Seed Lipoxygenase of Phaseolus vulgaris cv, Haricot

Phaseolus vulgaris cv, haricot seed lipoxygenase was extracted and partially purified. The precipitation of an active lipoxygenase fraction with solid ammonium sulfate (at 20–50% of saturation) increased its activity by a factor of 3. The pH for optimum activity was 7.3. The addition of 40 mM potassium cyanide resulted in a doubling of the enzyme activity. Enzyme activity was completely lost on storage at 4°C for 48 hr. The activity of haricot lipoxygenase extract was considerably greater on linoleic acid than on its esters, and decreased in the order: mono‐ > di > trilinolein. The haricot lipoxygenase shares many of the characteristics of the corresponding enzyme found in several seed sources.