Characterization of a Type II L-Asparaginase from the Halotolerant Bacillus subtilis CH11

L-asparaginases from bacterial sources have been used in antineoplastic treatments and the food industry. A type II L-asparaginase encoded by the N-truncated gene ansZP21 of halotolerant Bacillus subtilis CH11 isolated from Chilca salterns in Peru was expressed using a heterologous system in Escherichia coli BL21 (DE3)pLysS. The recombinant protein was purified using one-step nickel affinity chromatography and exhibited an activity of 234.38 U mg(-1) and a maximum catalytic activity at pH 9.0 and 60 degrees C. The enzyme showed a homotetrameric form with an estimated molecular weight of 155 kDa through gel filtration chromatography. The enzyme half-life at 60 degrees C was 3 h 48 min, and L-asparaginase retained 50% of its initial activity for 24 h at 37 degrees C. The activity was considerably enhanced by KCl, CaCl2, MgCl2, mercaptoethanol, and DL-dithiothreitol (p-value < 0.01). Moreover, the V-max and K-m were 145.2 mol mL(-1) min(-1) and 4.75 mM, respectively. These findings evidence a promising novel type II L-asparaginase for future industrial applications.

Automated summary

This study presents a novel type II L-asparaginase isolated from halotolerant Bacillus subtilis CH11 in Peru, which was successfully expressed and purified using a heterologous system. The enzyme showed high catalytic activity and holds potential for future industrial applications.