[Biological properties of L-asparaginase preparations from E. coli in cell cultures]

Non-specific cytotoxicity and specific antitumor activity of 5 preparations of L-asparaginase from E. coli were studied. Two cell line, i.e. the asparagine-dependent (Berkitt lymphoma cells) and asparagin-independent (human ovary cancer cells) were used as the test-system. Incorporation of 3H-thimidine into DNA was the criterion of the preparation effect on the cells. Preparation I with the specific activity of 60-90 IU per 1 mg of protein obtained at the first stages of purification had high non-specific cytotoxicity. Preparation II obtained after further purification of preparation I, as well as preparation II without any stabilizer with the specific activity of 200 IU/mg were not inferior to the "Bayer" preparation by their biological properties. Addition of L-asparaginase to the preparation as a stabilizer of excessive glycine (preparation IV) increased its non-specific cytotoxicity and interfered with the study of its properties in the cell systems. Mannitol (preparation V) had no effect on the biological activity of L-asparaginase preparation.