FIG. 2.

Thermal inactivation of the activity of mannose-6-phosphate isomerase from T. thermophilus at temperatures of 65 (•), 70 (▪), 75 (▴), 80 (○), and 85°C (□). A sample was withdrawn at each time interval, and the relative activity was determined in 50 mM PIPES buffer (pH 7.0) containing 10 mM l-ribulose, 10 U/ml of enzyme, and 0.5 mM Cu²⁺ at 75°C for 5 min. The data represent the means of three experiments, and the error bars represent standard deviations.