6533b7d2fe1ef96bd125ded5

RESEARCH PRODUCT

Stabilization of anti-leukemic enzyme l-asparaginase by immobilization on polysaccharide levan

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Abstract Biologically active fructose polymer levan from Zymomonas mobilis of different molecular mass (75 and 2000 kDa) was covalently coupled to anti-leukemic enzyme Erwinia carotovora l -asparaginase. The method used for the immobilization of the enzyme involved periodate oxidation of the polysaccharide, followed by reductive alkylation. A gentle periodate oxidation of levan (oxidation degree ≤24%) resulted in the highest residual enzyme activity (≥55%). The K m(app.) of glycoconjugates was higher than the K m of native l -asparaginase. The conjugation of l -asparaginase widened the optimum pH range of the enzyme. The electrophoretic mobility in polyacrylamide gel of glycoconjugates obtained was considerably reduced in comparison with native l -asparaginase. Immobilized l -asparaginase showed significantly higher stability in conditions of increased temperature (40°C and 50°C) and prolonged storage (1 month) in aqueous solutions as compared to the native enzyme. The results are discussed in relation to possible explanations of levan-induced enzyme stabilization, as well as to possible applications of immobilized l -asparaginase research.