The colominic acid was covalently coupled to L asparaginase molecule by reductive amination.Depending on the molar ratios of colominic acid asparaginase (30∶1,50∶1 and 100∶1),a modified enzyme molecule contained 4.7,7.2 and 12 colominic acid molecule,they retained 58%,56% and 33.2% of the initial asparaginase activity,respectively.In comparison with the native enzyme,modified enzyme had lower immunogenicity and antigenicity,longer half life time ( in vitro ),more resistance ability to trypsin proteolysis,and similar Km value for L asparagine.
