E·coli L-天冬酰胺酶B细胞抗原表位氨基酸残基Lys^(196)对其抗原性的影响

Effects of the Lys^(196) in antigenic epitopes of recombinant E.coli L-asparaginase on its antigenicity

目的:研究重组E.coli L-天冬酰胺酶B细胞抗原表位中关键氨基酸残基对其抗原性的影响。方法:以Ala为替代残基,对抗原表位192TPARKHTS199中Lys196进行PCR定点突变,双向免疫扩散法和间接ELISA法分析新型重组E.coli L-天冬酰胺酶的抗原性。结果:采用双向免疫扩散法和间接ELISA法检测,与重组E.coli L-天冬酰胺酶相比,新型重组E.coliL-天冬酰胺酶与重组E.coli L-天冬酰胺酶抗体结合率下降64%。结论:通过对重组E.coli L-天冬酰胺酶B细胞抗原表位关键残基的定点突变有效地降低了其抗原性。

Aim：To study the effects of critical amino acid residue in an immunodominant epitope on antigenicity of recombinant E. coli L-asparaginase. Methods： Lys^196 in octapeptide ^192TPARKHTS^199 was changed by side-directed mutagenesis. The mutant enzyme was expressed in E. coli pKAM/JM105-22 and purified. Antigenicity of mutant recombinant E. coli L-asparaginase was analyzed by double immunological diffusion and indirect ELISA. Results： Changing Lys^196 to Ala^196 reduced the antigenicity of the enzyme by 64%, as shown in indirect ELISA using polyclonal antibodies raised against the wild-type enzyme. Conclusion： The antigenicity of recombinant E. coli L-aspraginase can be significantly reduced by alteration of single critical residues without destroying its biological activity.