Abstract
In the near future, the demand for L-asparaginase is expected to rise several times due to an increase in its clinical and industrial applications in various industrial sectors, such as food processing. Streptomyces sp. strain NEAE-K is potent L-asparaginase producer, isolated and identified as new subsp. Streptomyces rochei subsp. chromatogenes NEAE-K and the sequence data has been deposited under accession number KJ200343 at the GenBank database. Sixteen different independent factors were examined for their effects on L-asparaginase production by Streptomyces rochei subsp. chromatogenes NEAE-K under solid state fermentation conditions using Plackett–Burman design. pH, dextrose and yeast extract were the most significant factors affecting L-asparaginase production. Thus, using central composite design, the optimum levels of these variables were determined. L-asparaginase purification was carried out by ammonium sulfate followed by DEAE-Sepharose CL-6B ion exchange column with a final purification fold of 16.18. The monomeric molecular weight of the purified L-asparaginase was 64 kD as determined by SDS-PAGE method. The in vitro effects of L-asparaginase were evaluated on five human tumor cell lines and found to have a strong anti-proliferative effects. The results showed that the strongest cytotoxic effect of L-asparaginase was exerted on the HeLa and HepG-2 cell lines (IC50 = 2.16 ± 0.2 and 2.54 ± 0.3 U/mL; respectively). In addition, the selectivity index of L-asparaginase against HeLa and HepG-2 cell lines was 3.94 and 3.35; respectively.
Highlights
L-asparaginase is one of the amidase group, that catalyzes the hydrolysis of L-asparagine and releases L-aspartic acid and ammonia[1]
El-Naggar et al.[26] have reported that soybean was used as substrate for production of L-asparaginase under solid state fermentation (SSF) conditions by Streptomyces brollosae NEAE-115
L-glutaminase activity was determined for the selected strain and the results demonstrated that the produced enzyme is glutaminase free L-asparaginase
Summary
L-asparaginase is one of the amidase group, that catalyzes the hydrolysis of L-asparagine and releases L-aspartic acid and ammonia[1]. Where the L-asparaginase production is Y and the independent factors are: A (incubation time), C (inoculum size), D (pH), E (temperature), G (dextrose), H (fructose), J (L-asparagine), K (K2HPO4), M (yeast extract), O (NaCl) and Q (CaCl2).
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