The recombinant producer strain expressing Rhodospirillum rubrum L asparaginase (RrA) has been obtained and a purification procedure of RrA has been developed. The purified enzyme, RrA, has the following biochemical and catalytic characteristics: K m for L Asn of 0.22 mM, pH optimum at 9.2; temper ature optimum at 54°C, pI = 5.1. RrA exhibited a significant cytotoxic effect towards the following cell lines: K562 (IC 50 = 1.80 U/mL), DU145 (IC 50 = 9.19 U/mL), and MDA MB 231 (IC 50 = 34.62 U/mL). Com parative analysis employing E. coli L asparaginase II type (EcA) and Erwinia carotovora L asparaginase (EwA) has shown that the enzyme cytotoxicity towards these cell lines decreased in the following order: EcA > RrA > EwA. Daily administration of RrA (4000 U/kg) to L5178y bearing mice for 10 days (total dose of 40000 U/kg) showed T/C = 172. Data obtained suggest that RrA may be referred to intracellular L aspar aginases with low L glutaminase activity and marked antiproliferative effect.

The recombinant producer of Rhodospirillum rubrum L-asparaginase (RrA) was received and purification procedure of RrA was developed. It was shown that RrA has following biochemical and catalytic characteristics: K for L-asn 0,22 мM, pH optimum 9,2; temperature optimum 54°С; pI=5,1±0,3; L-gln activity seems to be low-to-negligible. К562, DU145 and MDA-MB-231 cellular lines displayed significant sensitivity towards the enzyme (IC50=1,80; 9,19 and 34,62 ME/ml, respectively. In comparison with L-asparaginases from E . coli II type (EcA) and Erwinia carotovora (EwA) cytotoxicity of RrA seems to be higher than EwA, but lower than EcA. 10-fold i.p. RrA administration (4000 ME/kg per day) in L5178y bearing mice showed Т/С=172%. The received results show that RrA belongs to I type cellular L-asparaginases with low L-gln activity and the high antiproliferative effect.

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