Figure 1.

In vitro inactivation of soybean root GS by a MCO system. A 4-d-old root extract was incubated with an FeCl₃ solution (0.125 mm FeCl₃ and 50 mm imidazol, pH 7.4) and 5 mm DTT in the presence (○) or absence (•) of 1 mm EDTA for the times indicated. The incubation was at 4°C for the first 2 h and then at 30°C for the next 22 h. At each time the samples were assayed for transferase activity. Values are averages ± se from at least three independent experiments (n = 3–6).