Hydrolysis of phosphor-monoesters is an important process in biological systems linking energy metabolism and metabolic regulation. Phosphatases (EC 220.127.116.11) catalyse the hydrolysis of phospho-monoesters and phosphoproteins, and may be classified as acid phosphatases or alkaline phosphatases, depending on the optimum pH required for their activity. Acid phosphatases in plants help in mobilizing phosphate which is very important during seed germination. Thus, biochemical characterization of acid phosphatase from germinating chickpea seeds would help in elucidating the role of these enzymes in phosphate metabolism during germination. The present study involves the isolation and partial purification of an acid phosphatase from germinating chickpea (Cicer arientum) seeds. The enzyme was partially purified from germinated seeds using 80% ammonium sulphate. The acid phosphatase had a specific activity of 1.17 U.mg-1 of protein, and its 3.9 fold purification was achieved. The molecular weight of the enzyme determined by SDS-PAGE was 39 kDa. Biochemical characterization of the enzyme was carried out to determine the optimum incubation time, optimum temperature and optimum pH. The maximum enzyme activity was observed at 30 min of incubation, thereafter the activity decreased gradually. The optimum temperature for acid phosphatase activity was 50°C and its optimum pH was 5.0. The partially purified enzyme was found to have a Km of 0.25 mM and Vmax of 9I U.mg-1 of protein.
Keywords: Cicer arientum, acid phosphatase, germination, Km, Vmax