Clonorchis sinensis: molecular cloning and characterization of 28-kDa glutathione S-transferase.

A 28-kDa glutathione S-transferase (Cs28GST) was purified from a Clonorchis sinensis cytosolic fraction through anion-exchange and glutathione-affinity column chromatographies. A monoclonal antibody raised against Cs28GST reacted specifically to the C. sinensis antigen among trematode proteins. A putative peptide of 212 amino residues deduced from a cDNA clone appeared homologous with 28-kDa GST of trematodes, and its secondary structural elements predicted a GSH-binding site. Recombinant Cs28GST showed GST enzyme activity with CDNB substrate and was sensitive to the model inhibitors. The recombinant Cs28GST was antigenically indistinguishable from the native form and was recognized specifically by C. sinensis-infected human sera. The Cs28GST was localized in the tegument and underlying mesenchymal tissues. It is suggested that Cs28GST may play significant physiological roles against bioreactive molecules and be a useful reagent for serodiagnosis of clonorchiasis.