Abstract:Ca2+-ATPase activity of P. crispus root and leaf plasma membrane was studied by changing the solution conditions including temperature, pH value, ATP concentration, and calcium concentration. The results indicated that the activity of root plasma membrane Ca2+-ATPase reached the maximum at pH 6.0 and 40℃, while the leaf enzyme highly activated at a broad range of pH at an optimum reaction temperature of 45℃. Plasma membrane Ca2+-ATPase activity in the root reached the maximum at 3 mmol/L ATP and in the leaf at 4 mmol/L ATP in the solution. P. crispus root and leaf plasma membrane Ca2+-ATPase activity increased up to the presence of 10-4 mol/L calcium in the solution. The alteration of CaCl2 concentration in culture solution for P. crispus cultivation resulted in different Ca2+-ATPase activity in both root and leaf plasma membrane. The root plasma membrane Ca2+-ATPase activity was higher than in the leaf, and the difference was more remarkable with increments of calcium in the culture solution. At lower concentration of calcium than 10 mg/L (2.5×10-4 mol /L) in the culture solution, the Ca2+-ATPase activity was raised gradually. Between 10 mg/L to 15 mg/L, Ca2+-ATPase activity dropped sharply, which is in agreement with the impact of calcium concentration on Ca2+-ATPase activity.