Secretory expression and optimization of type II L-asparaginase from Pseudomonas sp. PCH199.

L-asparaginase (L-ASNase) is used to treat acute lymphoblastic leukemia and acrylamide reduction in food. Presently, recombinant L-ASNase formulations are produced in the cytoplasmic fractions of E. coli. Here, we describe an efficient approach for secretory expression of recombinant L-ASNase II (Pg-ASNase II) with pelB signal peptide in the E. coli expression host. Pg-asn II was successfully cloned and expressed in pET-26b(+) having pelB leader sequence for periplasmic expression. It led to the successful secretion of Pg-ASNase II in the supernatant. However, a significant amount of Pg-ASNase II was also left in the cytoplasmic space. The protein secretion increased from 0.33 to 0.77 mg mL-1 with 0.2 % Tween 80 in the medium. Pg-ASNase II was purified in a single chromatographic step using a Q-sepharose column with 8.0 mg L-1 purified protein production and 60.0 U mg-1Pg-ASNase II activity. It demonstrated a 75 % yield and a 15-fold increase in purification. The current study reported an increased extracellular L-ASNase expression compared to the wild organism and helped reduce the cost of the downstream process. Hence, this research can contribute to upcoming investigations of periplasmic Pg-ASNase II for therapeutic applications.