Antitumor Activity of L-Asparaginase from Chicken liver

This study aimed to isolate, purify and characterize L-asparaginase present in some animal tissues. The L-asparaginase (EC 3.5.1.1) produced by chicken livers was isolated and characterized. Different purification steps (including ammonium sulphate fractionation followed by separation on Sephadex G-100 gel filtration and Sephadex G-200 gel filtration) were applied to crude filtrate to obtain a pure enzyme preparation. The enzyme was purified 128.5 ± 0.5 fold and showed a final specific activity of 158.11 ± 5.0 U/mg with a 17.1 ± 8.6 % yield. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of the purified enzyme revealed it was one peptide chain with Mr of 33 kDa while by gel filtration appears to be 36 kDa. The enzyme was very specific to L-asparagine and did not hydrolyze L-glutamine. A Lineweaver-Burk analysis showed a Km value of 1.66 mM toward L-asparagine as substrate and Vmax of 34.47 U. The enzyme showed maximum activity at pH 11.0 when incubated at 60?C for 20 min. The amino acids composition of the purified enzyme was also determined. Antitumor activity was investigated. The enzyme inhibited the growth of the two human cell lines including hepatoc