Figure 3.

Effect of PA on purified sorghum leaf PEPC. A and B, Anionic phospholipids inhibit purified sorghum leaf PEPC. DAG, Diacylglycerol; TAG, triacylglycerol. C, Purified PEPC was incubated with PA (8:0) in 0.1 m Tris pH 8.0 at 30°C for 30 min as described in Supplemental Materials and Methods S1. Data are means ± se of three to six different experiments. a, P < 0.05 versus 0; b, P < 0.01 versus 0; c, P < 0.05 versus 100 (t test). D and E, Time courses of PEPC inactivation at different concentrations of PA (8:0). D, Black diamonds, 0 μm; white diamonds, 20 μm; black triangles, 40 μm; white triangles, 60 μm; black squares, 80 μm; white squares, 100 μm. Data are means of three experiments. Specific activity of the purified PEPC preparation was 50 unit mg⁻¹ protein. The results in Figure 3A corresponded to a concentration of 1 unit μm L⁻¹ (50 μm lipid, 30 min); for Figure 3B this was 3 unit mL⁻¹ (0.1 mm lipid, 30 min) as in Figure 3, C to E. se was always less than 12%.