Figure 4

Effect of temperature, pH, imidazole, and DTT on the purified ClPDI. The enzyme sample (1.0 μg) was heated at 37, 50, 60, 70, or 80°C for 20 min. At the end of each treatment, samples were assayed for CIPDI activity at pH 7.5 (A). Aliqouts of the enzyme sample were incubated with different pH buffers at 37°C for 1 h and then assayed for CIPDI activity (B). Imidazole was added to each enzyme sample (1.0 μg) to the final levels of 0.2, 0.4, 0.8 or 1.0 M and incubated at 37°C for 1 h and then assayed for CIPDI activity at pH 7.5 (C). DTT was added to each enzyme sample (1.0 μg) to the final levels of 10, 30, 70, 100 or 200 μM and incubated at 37°C for 5 min and then assayed for CIPDI activity at pH 7.5 (D). Data are means of three experiments.