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

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

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 K_m value, 2 mM, and enzyme specificity constant 7.7 mM^-1s^-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.

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.