AN ENZYME FROM EUCALYPTUS WHICH CONVERTS CINNAMOYL TRIACETIC ACID INTO PINOSYLVIN

An enzyme catalysing the cyclization of cinnamoyl triacetic acid to form pinosylvin was isolated from Eucalyptus sideroxylon leaves and purified by Sephades column chromatography. One enzyme preparation showed a 132-fold increase in specific activity and was fairly stable when stored as a freeze-dried preparation at 2-4°. The optimum pH of the reaction was at 8·2. Mg2+ at 2-10 mM concentration increased the rate of pinosylvin formation two and a half times, and Mn2+ and boron also stimulated the reaction rate to some extent. On the other hand, the enzyme was little affected by reagents such as p-chloromercuribenzoate but was strongly inhibited by KCN and cysteine, and also by mercury and iodine at high concentration. The function of this enzyme in plants is discussed. © 1970.