Abstract
L-Asparaginase (EC 3.5.1.1) is produced from actinomycetes to avoid the hypersensitive effect of that produced from other bacteria. Streptomyces halstedii strain was isolated from Egyptian soil and produced L-asparaginase. The 55.2-fold purified enzyme obtained had a final specific activity of 2071.2 U/mg. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed one band with molecular weight of 100 KDa. The Km value was 0.1939 mM. The enzyme showed maximum activity at pH 8.0, at optimum temperature at 37°C. Ethylene diamine tetraacetic acid (EDTA) and metal ions such as Zn2+, Hg2+ Cu2+ and K+ decreased the activity of the enzyme. Ions such as Ca2+ and Fe2+ did not affect the activity of the enzyme. The enzyme showed cytotoxic activity against Ehrlich ascites cells (EAC) in vitro. In vivo, it showed a significant reduction in malondialdehyde (MDA) levels as the end product of lipid peroxidation and a remarkable increase in activity of liver antioxidant enzymes, [superoxide dismutase (SOD), catalase (CAT)] and a reduction in tumor weight. In conclusion, L-asparaginase from S. halstedii showed anti-tumor activity and cytotoxic effect against cancer cell line in vitro and in vitro. The reduction of tumor size in albino mice may be attributed to the elevation of CAT and SOD activities as well as the diminishing of MDA. Key words: L-Asparaginase purification, antitumour activity, Streptomyces sp.
Highlights
L-Asparaginase (EC 3.5.1.1) is the first enzyme with antitumor activity intensively studied in human beings (Savitri and Azmi, 2003)
Production of L-asparaginase began after 72 h of cultivation (1.3 U/ml) and reached to maximum level (3.9 U/ml) after 120 h of incubation
They reached their maximum value at 70% saturation, they decreased by increasing ammonium sulfate concentration above 70%
Summary
L-Asparaginase (EC 3.5.1.1) is the first enzyme with antitumor activity intensively studied in human beings (Savitri and Azmi, 2003) It is used for the treatment of malignancies of the multiorgans (Kumar and Selvam, 2011). Since several types of tumor cells require L-asparagine for protein synthesis, they are deprived of an essential growth factor in the presence of L-asparaginase. The administration of this enzyme can digest its substrate resulting in starving and killing certain cancer cells (Basha et al, 2009; Kumar and Selvam, 2011). This fact suggested the development of this enzyme as a potent anti-tumor or anti-leukemic drug (Savitri and Azmi, 2003)
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