Purification and characterization of l-asparaginase from Pseudomonas aeruginosa strain SN004: Production optimization by statistical methods

Cancer cells have an abnormally high requirement for the l-asparagine and cannot make enough l-asparagine due to lack of l-asparagine synthetase. Consequently, administration of l-asparaginase withdraws dependent cancer cells of their extracellular source of l-asparagine and prime to apoptosis. In this study, SN004 strain was screened from different places in Kerman sweage as the best l-asparaginase producer and identified based on 16S rRNA sequence as Pseudomonas aeruginosa. Statistical methods were used to evaluate and optimize the effect of diverse parameters including pH, yeast extract, l-Asparagine, glucose, MgSO4, K2HPO4 and NaCl on l-asparaginase production. The maximum amount of l-asparaginase produced (785 U/ml) from the optimized medium containing l-asparagine (0.5%), glucose (0.2%), NaCl (0.045%) and K2HPO4 (0.045%). Purified enzyme showed a single band around 34 kDa on SDS-Page. SN004 l-asparaginase was active between pH values of 4.5-7.0 with an optimum at pH 5.0. In the presence of Mg2+, Mn2+, and Na+, it was detected that there was an increase in the l-asparaginase activity, whereas complete loss in activity was perceived in the presence of HgCl2. These results indicated that l-asparaginase from P. aeruginosa SN004 can be examined for medical applications.