Purification and Cytotoxicity of L-asparaginase from Streptomyces griseoluteus GDJ1

Abstract

L-asparaginase (L-asparagine amidohydrolase E.C.3.5.1.1) is an effective antineoplastic enzyme, used in acute lymphoblastic leukemia (ALL) chemotherapy. L-asparaginase activity of marine actinomycetes in soil samples of Agnitheertham (Rameswaram) and Periyar lake, Kumily were investigated. Totally fifty one actinomycetes were isolated from both the soil samples in different selective media. Out of fifty one isolates, four were found to produce L-asparaginase. Among them, the strain AT-R-S1 produced high amount of L-asparaginase. Hence it was selected for the further identification and based on molecular identification the strain AT-R-S1 was identified as Streptomyces griseoluteus GDJ1. Purification of the enzyme from the strain S.griseoluteus GDJ1 (AT-R-S1) was carried out. The final purification of the enzyme in CM-Sephadex C-50 column chromatography yielded 1.27 U/ml of enzyme in 0.09 mg of protein with a specific activity of 14.11 U/mg with approximately 119 folds purity. Cytotoxicity of different concentration of purified L-asparaginase was determined on VERO cells. The anti proliferative activity of L-asparaginase in MCF-7 and HeLa cells was determined and the EC 50 value was found to be 31.37 and 38.99 µg respectively. The above results were encouraging and worth pursuing for further development of Streptomyces griseoluteus GDJ1 (AT-R-S1) as an alternative resource for therapeutic L-asparaginase.