Characterization of a novel asparaginase from soil metagenomic libraries generated from forest soil.

OBJECTIVES: To screen soil metagenomic libraries for novel enzymes with enhanced activities.

RESULTS: To screen soil metagenomic libraries for novel enzymes with enhanced activities. A novel L-asparaginase was identified from forest soil metagenome and its characteristics were studied. The purified protein had a specific activity of 696 IU mg-1 and optimum activity at pH 7 and 35 °C. Enhanced enzyme activities were observed in the presence of Mg2+ , Ca2+ and K+ . The Km value, 2 mM, and enzyme specificity constant 7.7 mM-1 s-1 indicated that the recombinant enzyme has good substrate affinity to L-asparagine compared with commercially-available Escherichia coli asparaginase. The IC50 value of 0.78 µg ml-1 (0.47 IU ml-1 ) was observed with HL60 cell line and 0.39 µg ml-1 (0.23 IU ml-1 ) with MOLT-3 and MOLT-4 cell lines, which is better than that of commercially-available drugs.

CONCLUSION: The soil metagenome derived L-asparaginase with enhanced activities could be a potential candidate to develop as a drug in Acute Lymphoblastic Leukemia (ALL) therapy.