Purification, Characterization and Anticancer Activity of L-asparaginase Produced by Marine Aspergillus terreus

Abstract

L-asparaginase (E.C.3.5.1.1) is an enzyme responsible for hydrolysis of L-asparagine into aspartic acid and ammonia, and has its significant applications in the therapeutics and food technology. It was produced by the marine Aspergillus terreus and precipitated by 65% ammonium sulphate, followed by purification using gel filtration on Sephadex G-100 and DEAE-cellulose ion exchange chromatography, which yielded 11.96 fold purification. The molecular weight of the purified L-asparaginase was approximately 85 kDa, determined by a sodium dodecyl sulphate polyacrylamide gel electrophoresis. L-asparaginase showed high affinity for L-asparagine with a Km of 31.5 mM and Vmax of 500 U/ml. The optimum pH and temperature of the purified enzyme were 5.8 and 40 o C, respectively. The L-asparaginase enzyme was stable from pH 4 to 5.8 and stable up to 70 o C. The effect of activators and inhibitors was studied providing that CdCl2 , Pb Cl2 , and Hg Cl2 strongly inhibited the enzyme activity, while Na Cl highly enhanced activity. Anticancer activity of the purified L-asparaginase was detected against HCT-116, Hep-G2 and MCF-7 cell lines with IC50 ranged from 3.79-12.6 µg/ml.