•A three-step purification scheme was successfully established for a recombinant protein rG17PE38.•The purity of the purified protein could reach 95% or so, and its activity and stability were not affected after purification.•Inducing cell apoptosis was demonstrated to be one of the cytotoxicity mechanisms of rG17PE38.A protein with high purity has become an essential pre-requisite for investigating its bioactivity, molecular structure and characteristics. Therefore, the development of technologies for efficient purification of protein is urgently necessary. The objective of this study was to establish a purification protocol for a recombinant protein rG17PE38. Different forms of chromatography such as hydrophobic interaction and ion exchange chromatography were chosen as the core purification steps. The performance of each technique was optimized to meet the requirements and the purification steps were arranged in a logical way of facilitating to operate in next step. In addition, some characteristics of the protein such as stability, bioactivity and cellular location were determined. Finally, whether the protein could induce cell apoptosis was also explored. The results showed the protein purified via the suggested three-step purification scheme could obtain a purity of 95%, and its bioactivity in the form of IC50 was 17.6 ng/mL, furthermore it could keep stable at 4 °C for at least 10 days. The protein could bind on its target cell membrane specifically, and inducing cell apoptosis was demonstrated to be one of the cytotoxicity mechanisms of the protein. Results obtained in our study may provide useful information on strategies of protein purification and lay a substantial foundation for the followed animal or clinical experiments on rG17PE38.

Okadaic acid (OA) and analogues of dinophysistoxin (DTX) are key diarrheic shellfish poisoning (DSP) toxins, which possibly arouse DSP symptoms by consuming the contaminated shellfish. Because of the stable toxicity in high temperature and the long-term carcinogenicity, the outbreaks of DSP related to consumption of bivalve mollusks contaminated by DSP toxins pose a hazard to public health. Therefore, it is worth developing a fast and reliable analytical method for the detection of OA and analogues in shellfish. In this paper, an indirect competitive enzyme-linked immunosorbent assay (ELISA) (icELISA) for detecting OA and DTX-1 in seafood was developed based on monoclonal antibody (McAb).The OA was conjugated to human immunoglobulin G (IgG) and bovine serum albumin (BSA) by the active ester method as the immune antigen and the detective antigen. The spleen cells from BALB/c mice immunized with OA-IgG were fused with SP2/0 myeloma cells. A hybridoma cell line, which secreted McAb against OA, was selected by “limiting dilution” cloning. An icELISA was developed based on immobilized conjugate (OA-BSA) competing the McAb with the free OA in seafood sample.A hybridoma cell line, which secreted IgG1 subclass monoclonal antibody (McAb) against OA, was selected. The IC50 of the McAb for OA and dinophytoxin-1 (DTX-1) were 4.40 and 3.89 ng/mL, respectively. Based on the McAb, an indirect competitive ELISA for detection of OA and DTX-1 in seafood was developed. The regression equation was y = 54.713x − 25.879 with a coefficient correlation of R2 = 0.9729. The linear range and the limit of detection were 0.4–12.5 and 0.45 ng/mL, respectively. The average recovery of OA and DTX-1 spiked shellfish was 82.29% with the coefficient of variation of 7.67%.The developed icELISA is a fast, sensitive, and convenient assay for detecting of total amount of OA and DTX-1 in seafood.