Influence of Age and Sulfur Metabolism on ATP Sulfurylase Activity in the Soybean and a Survey of Selected Species

ATP sulfurylase activity varied greatly among different leaves on the soybean plant [Glycine max (L.) Meer.], and high levels of activity did not appear in the leaves until the seedlings were about 3 weeks old. In general, leaves from the top of the plant had a higher activity than leaves from the bottom of the plant. A much greater activity was found in soybean leaves than in soybean roots. The absence of sulfate in the nutrient solution resulted in higher enzyme activity in leaves from young plants and in lower activity in leaves from older plants. Over the growing season, however, ATP sulfurylase activity appeared to be related to sulfur content of the leaf. Several other plant species also had measurable levels of ATP sulfurylase.