Inhibition of Broad Bean Lipoxygenase

The enzyme lipoxygenase (E.C.1.13.1.13) was extracted from broad bean ( Vicia faba ) and purified 50‐fold. The enzyme reaction was inhibited by phenolic antioxidants, the broad bean coat itself, sulfhydryl compounds, sulfhydryl reagents, and by metal binding agents. The inhibition by metal binding agents could be reversed by the addition of Ca ++ and Mn ++ . Dialysis against 1 × 10 −3 M cyanide for 24 hr resulted in a complete loss of activity which could be regained by the addition of calcium. The enzyme was completely denaturated by heating at 75°C for 10 sec. A 2‐min blanch of the fresh broad beans in boiling water or steam completely inactivated the enzyme.