Comparison of Enzymatic Activity of Novel Recombinant L-asparaginases of Extremophiles

The activity of novel uncharacterized extremophilic L-asparaginases from the psychrophilic fungi Sclerotinia borealis, the thermoacidophilic crenarchea Acidilobus saccharovorans, and the thermophilic bacteria Melioribacter roseus were studied. Active enzymes were produced via the expression of the native L-asparaginase gene from M. roseus (MrA) and synthetic genes encoding fungal S. borealis (SbA) and archeal A. saccharovorans (AsA) L-asparaginases after codon optimization in Escherichia coli cells. In the study, the maximum specific activity at different temperatures and pH was observed for MrA. The activity of MrA crude extract was highest at 75°С and a pH of 9.0. Metal ions (1 mM) differed in their effects on enzyme activity. Сu2+ and Zn2+ ions completely abolished enzyme activity. Changes in the specific activity of MrA crude extract in the presence of Fe3+, Ni2+, Ca2+, and Mg2+ varied within 5–28%. Our findings show that L-asparaginase of M. roseus may be a promising object for the further study of enzymatic properties and biotechnological applications.