Abstract: Objective To produce prokaryotic recombinant protein glyceraldehyde-3-phosphate dehydrogenase of Clonorchis sinensis (CsGAPDH), analyze its enzyme activity and immunological function. Methods The recombinant CsGAPDH was purified according to the protocol of GST·BindTM kit and was digested with thrombin proteinase and eluted with wash buffer. The BALB/c mice were inoculated with the purified protein. The antisera collected from the mice were used to detect the titres of IgG antibodies by ELISA, and Western blotting was used to identify the specificity of the antisera with the purified CsGAPDH. S-P immunohistochemistry method was used to confirm the expression and distribution of CsGAPDH in adult Clonorchis sinensis with the polyclonal antibodies from immunized BALB/c mice. The CsGAPDH catalytic activity was evaluated employing the conventional substrate glyceraldehydes-3-phosphate (3-GAP). Results SDS-PAGE showed a single purified protein band. Gel scanning analysis revealed that the protein purity of CsGAPDH was 90%. ELISA analysis showed an increased IgG value. S-P immunohistochemistry analysis demonstrated that the recombinant plasmid pGEX-4T-1-GAPDH expressed and distributed in muscle cell membrane of immune mice. Western blotting result suggested that CsGAPDH protein contained essential epitopes with high antigenic activities. This protein CsGAPDH could catalyzed 3-GAP with enzymatic active unit of 2 872 U min^-1ml^-1. Conclusion The recombinant protein CsGAPDH shows a proper enzymatic activity and immunogenicity.

Key words: Clonorchis sinensis, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Western blotting, Immunogenicity