Biotechnology Letters, Vol.26, No.9, 753-756, 2004
Chemical modification of L-asparaginase from Escherichia coli with a modified polyethyleneglycol under substrate protection conditions
L-Asparaginase was chemically modified with 2,4-bis(O-methoxypolyethyleneglycol)-6-chloro-S-triazine (mPEG(2)) in the presence of L-asparagine. Optimal modification was performed under the condition that the molar ratio of mPEG(2)/-NH2 is 10. The modified enzyme retained 33% of initial enzymatic activity with complete abolishment of immunogenicity. In vitro half-life increment from 4.6 h to 33 h has been obtained.