A STUDY ON 3-DEOXY-D-ARABINO-HEPTULOSONIC ACID 7-PHOSPHATE SYNTHASE IN HIGHER PLANTS

Several plant tissues were assayed for DAHP synthase activity.The activity was found in most of the plants examined, and thehighest activity was detected in developing mung bean plants.During the growth of mung bean shoots, the highest level ofthe activity on protein basis was seen 6 to 8 days after sowing. Some properties of DAHP synthase were investigated using theenzyme preparation mainly from mung bean shoots. The productof the reaction was identified as DAHP by paper chromatographyof the reaction mixture and by the absorption spectrum of thederivative formed by periodate-TBA treatment. Mg⁺⁺ at 1–5mM concentration increased the rate of DAHP formation threeto four times, although the enzyme was still active in the absenceof Mg⁺⁺. Optimal pH was found to be between pH 7.2 and 7.9.Relationship between the rate of DAHP formation and concomitantacid phosphate activity in enzyme preparations was discussed. (Received July 20, 1967; )