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

Abstract

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 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.

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.

Keywords: Acute Lymphoblastic Leukemia; Anticancer; L-Asparaginase; Metagenomics; Therapeutic enzyme.