Figure 2.

Effects of reduced thioredoxin on plastidic ACCase activity. (A) Pea plastidic ACCase was preincubated with various concentrations of thioredoxin (oxidized form) in the presence (○) and absence (•) of 50 μM DTT or reduced thioredoxin (□) at 30°C for 10 min, and the reaction was started as in Fig. 1B. For no DTT, thioredoxin (oxidized form) was added. (B) Pea plastidic ACCase was preincubated with various concentrations of DTT in the presence (○) and absence (•) of 32 μM thioredoxin at 30°C for 10 min, and treated as in A. The final concentration of DTT was indicated. The activity in the presence of thioredoxin was divided by that in its absence at various DTT concentration, and the value obtained was plotted as enhancement (□). (C) Various concentrations of E. coli thioredoxin (○), spinach thioredoxin-f (•) or -m (□) were incubated with 50 μM DTT at 20°C for 10 min to reduce thioredoxin, and then the pea plastidic ACCase was added. After the mixture was further incubated at 30°C for 10 min, the enzyme reaction was started as in Fig. 1B. The final concentrations of thioredoxins were indicated.